CA2040572C - Cordless key telephone system capable of quickly answering incoming calls - Google Patents
Cordless key telephone system capable of quickly answering incoming callsInfo
- Publication number
- CA2040572C CA2040572C CA002040572A CA2040572A CA2040572C CA 2040572 C CA2040572 C CA 2040572C CA 002040572 A CA002040572 A CA 002040572A CA 2040572 A CA2040572 A CA 2040572A CA 2040572 C CA2040572 C CA 2040572C
- Authority
- CA
- Canada
- Prior art keywords
- signal
- cordless
- station
- access units
- stations
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W84/00—Network topologies
- H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
- H04W84/10—Small scale networks; Flat hierarchical networks
- H04W84/16—WPBX [Wireless Private Branch Exchange]
Abstract
In a cordless key telephone system, access units are located in groups corresponding to service areas for broadcasting radio signals on a control channel or on an assigned speech channel to cordless stations. A main controller selects one of the access units for each service area in response to an incoming call from the switched telephone network and sends a first alert signal to the selected access units to cause them to broadcast a recurrent sequence of second alert signals containing the identifiers of standby cordless stations. The second alert signal is received by each standby cordless station and an ACK signal is transmitted if the received signal contains its identifier. The ACK signal is copied by each access unit for transmission to the main controller, whereupon it returns a proceed-to-assign signal if the number of the received copies of the ACK signals is equal to the number of all standby stations. The proceed-to-assign signal is received by the selected access units and a channel assignment signal is broadcast indicating the assigned channel. On receiving it, each station is switched to the assigned channel and one of the stations in each area transmits an end-of-switching signal to cause the access units to broadcast ringing signals containing the identifiers of the alerted stations. In response to a given cordless station going off hook, an off-hook signal is sent from it and copied by the associated access unit for transmission to the main controller, which returns a turn-on signal to allow the given station to activate its speech circuit.
Description
TITLE OF THE INVENTION
2 "Cordless Key Telephone System Capable of Quickly Answering 3 Incoming Calls"
s The present invention relates to a cordless key telephone system.
6 Cordless key telephone systems have been in use today replacing 7 wired key telephone systems as they considerably reduce the amount of 8 cables and wires laid on office floors the arrangement of which must be g altered to meet current needs of working environment. The system includes a main controller which is coupled to the public or private 11 switched telephone network via subscriber loops to receive incoming calls 12 and originate outgoing calls. The floor space which the system covers is 13 divided into several service areas. One or more access units are located in14 each service area and coupled to the main controller to exchange control signals with it. In response to an incoming call, the main controller selects 16 one access unit for each service area and sends an alert signal to it. Each17 selected access unit then broadcasts a recurrent sequence of alert signals 18 respectively containing the identifiers of all standby cordless stations to19 elicit a response therefrom. Each standby cordless station responds to 20 the alert signal addressed to it by returning an acknowledgment signal 21 containing in it the own station identifier as well as the system identifier.22 Each selected access unit waits until it receives the acknowledgment 23 signals from all standby cordless stations and communicates this fact to 24 the main controller. The main controller waits for this communication 25 from each selected access unit to return a proceed-to-assign signal to 26 allow it to broadcast a channel assignment signal to switch the standby 27 cordless stations to an assigned speech channel on which ringing signals 28 will then be transmitted. If this communication is not received within a 29 prescribed timeout period, the main controller automatically sends the proceed-to-assign æignal to each selected access unit. When one of the cordless station goes off hook, this fact is signaled by the associated access unit to the main controller, whereupon it establishes a connection between the network and the accesæ unit from which the off-hook condition is signaled.
Since the cordless stations may roam across the boundaries between the service areas of the æystem and since the access units have no way of knowing this fact, the timeout period for receiving acknowledgments from all stations often expires, resulting in a delayed action for answering an incoming call.
In addi~ion, it i8 the usual practice to include a battery savings circuit in the cordless stations. Upon completion of an incoming call to a certain standby cordless station, the ol;her standby cordless stations are automatically switched to the battery savings mode. If another incoming call is received immediately following the previous call, however, all other cordless stations are in their battery savings mode and there is an inevitable delay in alerting the stations until their power supplies are turned on again.
It is therefore an ob~ect of the present invention to provide a cordless key telephone system which is capable of answering incoming calls without wasting time.
According to one aspect, the present invention provides in a cordless key telephone system having a plurality of access units divided into groups corresponding respectively to service areas for broadcasting radio signals on a two-way control channel -or on an assigned two-way speech channel, a plurality of cordless stations, and a main controller coupled to a switched telephone network for selecting one of the accesæ units for each of said service areas in response to an incoming call from said network and transmitting a first alert signal to the selected access units, a method comprising the steps of: a) receivinq said first alert signal and, in response thereto, broadcasting from the selected access units a recurrent sequence of second alert signals over the control channel, the second alert signals respectlvely identifying standby cordless stations; b) receiving the second alert signal and, in response thereto, transmitting an acknowledgment signal over the control channel from each cordless station if the received second alert signal identifies the cordless station; c) receiving the acknowledgment signal and, in response thereto, transmitting a copy thereof from each of the selected access units to said main controller; d) receiving said copy of the acknowledgment signal from the selected access units and, in response thereto, transmitting a proceed-to-assign signal from said main controller to ~aid selected access units if the number of the received copies of the acknowledgement si.gnals is equal to the number of all standby cordless stations; e) receiving said proceed-to-assign signal and, in response thereto, broadcasting a channel assignment signal over the control channel from said selected access units, said channel assignment signal identifying said assigned speech channel; f) receiving said channel assignment signal and, in response thereto, transmitting an end-of-switching signal over the assigned speech channel from one of the cordless stations which are located in each of said areas; g) receiving said end-of-switching signal and, in response thereto, broadcasting from each of the selected access units ringing signals over the assigned speech channel, the ringing signals respectively identifying the cordless stations which have transmitted said acknowledgment signals; h) receiving the ringing signal and, in response thereto, generating a ringing tone in each cordless station if the received signal identifies the cordless station and allowing an off-hook signal to be transmitted over the assigned speech channel from a replying cordless station; i) receiving the off-hook signal and, in response thereto, transmitting a copy thereof from one of the selected access units to said main controller; j) returning a turn-on signal from the main controller as a response to said copy of the off-hook signal, said turn-on signal identifying the replying cordless station;
k) receiving said turn-on signal and, in response thereto, broadcasting a copy thereof from said access unit; and 1) causing said replying cordless station to receive said copy of the turn-on signal and establish a speech circuit thereof.
Since the proceed-to-assign signal is transmitted from the main controller to the selected access units at the moment when acknowledgment signals from all standby cordless stations are received by the main controller, the time taken to answer incoming calls from the network can be significantly reduced.
According to a more specific feature of this invention, each cordless station is switched from the assigned speech channel to the control channel for a prescribed period of time if it ~, 2040~72 receives a copy of the turn-on signal which does not contain the identifier of the station and periodically turns off its power supplies to power draining units following the end of the prescribed period. In a modified embodiment, upon receipt of the copy of the off-hook slgnal, a proceed-to-clear signal is transmitted from the main controller to the selected access units othex than one from which it received the copy of the off-hook signal to cause them to broadcast clearing signals respectively containing the identifiers of the cordless stations not going off hook. In response to the clearing signal, the addressed cordless station is switched from the assigned speech channel to the control channel for a prescribed period of time and periodically turns off power supplies to its power draining units following the end of the prescribed period.
According to another broad aspect, the present invention provides a cordless key telephone system for covering a plurality of service areas in which cordless stations are located, comprising: a plurality of access units divided into groups corresponding respectively to said service areas, the access units of each group being located in the corresponding service area for broadcasting signals on a two-way control channel or on an assigned two-way speech channel; a main controller coupled to a switched telephone network for selecting one of the access units for each of said service areas in response to an incoming call from said network and transmitting a first alert signal to the selected access units; each of said access units being responsive to said first alert signal for broadcasting over the control 4a . ~O>~V~
channel a recurrent sequence of second alert signals respectively identifying standby cordless stations, responsive to receipt of an acknowledgment signal from the cordless stations for transmitting a copy of the acknowledgment signal to said main controller, responsive to receipt of a proceed-to-assign signal from said main controller for broadcasting over the control channel a channel assignment signal identifying an assigned speech channel, responsive to receipt of an end-of-switching signal from the cordless stations for sequentially broadcasting over the assigned speech channel ringing signals respectively identifying the cordless stations which returned said acknowledgment signals, responsive to an off-hook signal from a replying cordless station for transmitting a copy of the off-hook signal to said main controller, and responsive to receipt of a turn-on signal from said main controller identifying the replying cordless station for broadcasting over the assigned speech channel a copy of said turn-on signal, said main controller transmitting said proceed-to-assign signal if the number of the copies of the acknowledgment signals from said selected access units is e~ual to the number of all standby cordless stations, and transmitting said turn-on signal to one of the selected access units if said copy of the off-hook signal is received therefrom, each of said cordless stations being responsive to the second alert signal identifying the cordless station for transmitting over the control channel said acknowledgment signal, responsive to the channel assignment signal for transmitting over the assigned speech channel said end-of-switching signal, 4b j ~[, ...
responsive to the cordless station going off hook in response to the rlnging signal identifying the cordless station for transmitting over the assigned speech channel said off-hook signal, and responsive to said copy of turn-on signal identifying the cordless station for establishing a speech circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be described in further detail wlth reference tQ the accompanying drawings, in which~
Fig. 1 shows in block form a cordless key telephone system ~ 4c embodying the present invention;
2 Fig. 2 shows details of a main controller;
3 Fig. 3 shows details of an access unit;
4 Fig. 4 shows details of a cordless station;
s Fig. 5 shows a sequence of programmed instructions performed by 6 the main controller;
6 Cordless key telephone systems have been in use today replacing 7 wired key telephone systems as they considerably reduce the amount of 8 cables and wires laid on office floors the arrangement of which must be g altered to meet current needs of working environment. The system includes a main controller which is coupled to the public or private 11 switched telephone network via subscriber loops to receive incoming calls 12 and originate outgoing calls. The floor space which the system covers is 13 divided into several service areas. One or more access units are located in14 each service area and coupled to the main controller to exchange control signals with it. In response to an incoming call, the main controller selects 16 one access unit for each service area and sends an alert signal to it. Each17 selected access unit then broadcasts a recurrent sequence of alert signals 18 respectively containing the identifiers of all standby cordless stations to19 elicit a response therefrom. Each standby cordless station responds to 20 the alert signal addressed to it by returning an acknowledgment signal 21 containing in it the own station identifier as well as the system identifier.22 Each selected access unit waits until it receives the acknowledgment 23 signals from all standby cordless stations and communicates this fact to 24 the main controller. The main controller waits for this communication 25 from each selected access unit to return a proceed-to-assign signal to 26 allow it to broadcast a channel assignment signal to switch the standby 27 cordless stations to an assigned speech channel on which ringing signals 28 will then be transmitted. If this communication is not received within a 29 prescribed timeout period, the main controller automatically sends the proceed-to-assign æignal to each selected access unit. When one of the cordless station goes off hook, this fact is signaled by the associated access unit to the main controller, whereupon it establishes a connection between the network and the accesæ unit from which the off-hook condition is signaled.
Since the cordless stations may roam across the boundaries between the service areas of the æystem and since the access units have no way of knowing this fact, the timeout period for receiving acknowledgments from all stations often expires, resulting in a delayed action for answering an incoming call.
In addi~ion, it i8 the usual practice to include a battery savings circuit in the cordless stations. Upon completion of an incoming call to a certain standby cordless station, the ol;her standby cordless stations are automatically switched to the battery savings mode. If another incoming call is received immediately following the previous call, however, all other cordless stations are in their battery savings mode and there is an inevitable delay in alerting the stations until their power supplies are turned on again.
It is therefore an ob~ect of the present invention to provide a cordless key telephone system which is capable of answering incoming calls without wasting time.
According to one aspect, the present invention provides in a cordless key telephone system having a plurality of access units divided into groups corresponding respectively to service areas for broadcasting radio signals on a two-way control channel -or on an assigned two-way speech channel, a plurality of cordless stations, and a main controller coupled to a switched telephone network for selecting one of the accesæ units for each of said service areas in response to an incoming call from said network and transmitting a first alert signal to the selected access units, a method comprising the steps of: a) receivinq said first alert signal and, in response thereto, broadcasting from the selected access units a recurrent sequence of second alert signals over the control channel, the second alert signals respectlvely identifying standby cordless stations; b) receiving the second alert signal and, in response thereto, transmitting an acknowledgment signal over the control channel from each cordless station if the received second alert signal identifies the cordless station; c) receiving the acknowledgment signal and, in response thereto, transmitting a copy thereof from each of the selected access units to said main controller; d) receiving said copy of the acknowledgment signal from the selected access units and, in response thereto, transmitting a proceed-to-assign signal from said main controller to ~aid selected access units if the number of the received copies of the acknowledgement si.gnals is equal to the number of all standby cordless stations; e) receiving said proceed-to-assign signal and, in response thereto, broadcasting a channel assignment signal over the control channel from said selected access units, said channel assignment signal identifying said assigned speech channel; f) receiving said channel assignment signal and, in response thereto, transmitting an end-of-switching signal over the assigned speech channel from one of the cordless stations which are located in each of said areas; g) receiving said end-of-switching signal and, in response thereto, broadcasting from each of the selected access units ringing signals over the assigned speech channel, the ringing signals respectively identifying the cordless stations which have transmitted said acknowledgment signals; h) receiving the ringing signal and, in response thereto, generating a ringing tone in each cordless station if the received signal identifies the cordless station and allowing an off-hook signal to be transmitted over the assigned speech channel from a replying cordless station; i) receiving the off-hook signal and, in response thereto, transmitting a copy thereof from one of the selected access units to said main controller; j) returning a turn-on signal from the main controller as a response to said copy of the off-hook signal, said turn-on signal identifying the replying cordless station;
k) receiving said turn-on signal and, in response thereto, broadcasting a copy thereof from said access unit; and 1) causing said replying cordless station to receive said copy of the turn-on signal and establish a speech circuit thereof.
Since the proceed-to-assign signal is transmitted from the main controller to the selected access units at the moment when acknowledgment signals from all standby cordless stations are received by the main controller, the time taken to answer incoming calls from the network can be significantly reduced.
According to a more specific feature of this invention, each cordless station is switched from the assigned speech channel to the control channel for a prescribed period of time if it ~, 2040~72 receives a copy of the turn-on signal which does not contain the identifier of the station and periodically turns off its power supplies to power draining units following the end of the prescribed period. In a modified embodiment, upon receipt of the copy of the off-hook slgnal, a proceed-to-clear signal is transmitted from the main controller to the selected access units othex than one from which it received the copy of the off-hook signal to cause them to broadcast clearing signals respectively containing the identifiers of the cordless stations not going off hook. In response to the clearing signal, the addressed cordless station is switched from the assigned speech channel to the control channel for a prescribed period of time and periodically turns off power supplies to its power draining units following the end of the prescribed period.
According to another broad aspect, the present invention provides a cordless key telephone system for covering a plurality of service areas in which cordless stations are located, comprising: a plurality of access units divided into groups corresponding respectively to said service areas, the access units of each group being located in the corresponding service area for broadcasting signals on a two-way control channel or on an assigned two-way speech channel; a main controller coupled to a switched telephone network for selecting one of the access units for each of said service areas in response to an incoming call from said network and transmitting a first alert signal to the selected access units; each of said access units being responsive to said first alert signal for broadcasting over the control 4a . ~O>~V~
channel a recurrent sequence of second alert signals respectively identifying standby cordless stations, responsive to receipt of an acknowledgment signal from the cordless stations for transmitting a copy of the acknowledgment signal to said main controller, responsive to receipt of a proceed-to-assign signal from said main controller for broadcasting over the control channel a channel assignment signal identifying an assigned speech channel, responsive to receipt of an end-of-switching signal from the cordless stations for sequentially broadcasting over the assigned speech channel ringing signals respectively identifying the cordless stations which returned said acknowledgment signals, responsive to an off-hook signal from a replying cordless station for transmitting a copy of the off-hook signal to said main controller, and responsive to receipt of a turn-on signal from said main controller identifying the replying cordless station for broadcasting over the assigned speech channel a copy of said turn-on signal, said main controller transmitting said proceed-to-assign signal if the number of the copies of the acknowledgment signals from said selected access units is e~ual to the number of all standby cordless stations, and transmitting said turn-on signal to one of the selected access units if said copy of the off-hook signal is received therefrom, each of said cordless stations being responsive to the second alert signal identifying the cordless station for transmitting over the control channel said acknowledgment signal, responsive to the channel assignment signal for transmitting over the assigned speech channel said end-of-switching signal, 4b j ~[, ...
responsive to the cordless station going off hook in response to the rlnging signal identifying the cordless station for transmitting over the assigned speech channel said off-hook signal, and responsive to said copy of turn-on signal identifying the cordless station for establishing a speech circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be described in further detail wlth reference tQ the accompanying drawings, in which~
Fig. 1 shows in block form a cordless key telephone system ~ 4c embodying the present invention;
2 Fig. 2 shows details of a main controller;
3 Fig. 3 shows details of an access unit;
4 Fig. 4 shows details of a cordless station;
s Fig. 5 shows a sequence of programmed instructions performed by 6 the main controller;
7 Figs. 6A and 6B show a sequence of programmed instructions 8 performed by the access units;
9 Figs. 7A to 7C show a sequence of programmed instructions performed by the cordless stations; and 11 Fig. 8 shows a sequence of signals exchanged through the system in 12 response to an incoming call from the switched telephone network.
1 4 Referring now to Fig. 1, there is shown a cordless key telephone system according to the present invention. The system includes a main 16 controller 2 connected to the public telephone network 1 via three 17 subscriber lines 61 through 63, for example. Main controller 2 is further 18 connected by local lines 71~74 to access units 41~44 which are divided 19 into two groups corresponding to service areas 31 and 32 and located at 20 strategic points of the corresponding service areas. The system has four 21 cordless stations 51 through 54, for example, which may roam across the 22 boundaries between service areas 31 and 32. A two-way control channel 23 iS provided between the access units and cordless stations. During 24 standby modes, all access units and cordless stations are switched to the 2 S control channel to constantly monitor the signals carried on that channel.
26 During a call origination or termination phase, tne control channel is used 27 to exchange control signals to assign a two-way speech channel.
28 As shown in Fig. 2, main controller 2 comprises line interfaces 81~83 29 respectively coupled via subscriber lines 61-63 to the network 1, local --6 20b~7~
interfaces 101~104 respectively coupled to local lines 71-74~ and a 2 switching matrix 9 for establishing a connection between the interfaces 8 3 and 10. A control circuit 11 is coupled to all interfaces 8 and 10 to supply 4 a switching control signal to matrix 9 in a manner as will be described.
As illustrated in Fig. 3, each access unit 4k includes a hybrid 12 having 6 its two-wire circuit coupled to the associated local line 7k. The transmit 7 portion of the four-wire circuit is coupled to the input of a transmitter 13,8 the receive portion of the four-wire circuit being coupled to the output of 9 a receiver 14. The output of transmitter 13 is coupled via a duplexer 15 to 10 an antenna 16 for transmission to cordless stations. Signals received by 1 1 antenna 16 from cordless stations are coupled by duplexer 15 to the input 12 of receiver 14 for transmission to main controller 2. A frequency 1 3 synthesizer is included in transmitter 13 and receiver 14 to receive control14 signals transmitted on the control channel from both sides of the access 15 unit for coupling to a control circuit 17. In a manner to be described, 16 controJ circuit 17 processes the received control signals and generates 17 control signals for transmission to either side of the unit. An alert signal 18 generator 18 is connected to the control circuit to generate station alert 19 signals in succession to all cordless stations of the system in response to 20 an enable signal from control circuit 17. Each alert signal contains the 21 system identifier and the identifier of each cordless station. The output of 22 alert signal generator 18 is applied to transmitter 1 3 for transmission to 2 3 cordless stations.
24 In Fig. 4, signal from the nearby access unit is detected by an antenna 25 19 of each cordless station 5k and passed through a duplexer 20 to a 26 receiver 21 where it is converted to an audio-frequency signal and 27 applied through a normally open switching circuit 22 to an earphone 23.
2 8 Signal from microphone 24 is coupled through switching circuit 22 to a 29 transmitter 25 where it is converted to a high-frequency signal and applied through duplexer 20 to antenna 19. A field intensity detector 26 is connected to receiver 21 to compare the field intensity of the cordless station with a prescribed threshold and applies an output signal to a control circuit 27 if the field intensity is higher than the threshold. As will be described, control circuit 27 exchanges control signals with receiver 21 and transmitter 25 by tuning their frequency synthesizers to the control channel and switching to a speech channel when it is assigned by the communicating access unit. For power savings purposes, a power switch 28 is controlled by control circuit 27 to cut off power supplies from a battery 29 to receiver 21 and transmitter 25. A tone ringer 30 is connected to control circuit 27 to audibly alert the user upon receipt of an incoming call from the network. A keypad 31 is also connected to control circuit 27 to generate an off-hook signal when answering an incoming call or generate a connection request as well as destination address information when originating an outgoing call.
Each of the respective control circuits of main controller 2, access units 4 and cordless stations 5 is a microprocessor-based controller which is programmed to perform a stored sequence of instructions as described hereinbelow.
FLOWCHARTS
In Fig. 5, main controller 2 initiates program execution with sequential steps 41, 42 and 43 which check in succession for the presence of an incoming call from the network on one of subscriber lines 61, 62 and 63. If there is one, control proceeds to step 44 to select two access units one for each service area and send a first alert signal to both of the selected access units in order to wait for copied versions of acknowledgment (ACK) signals from cordless stations which are in a standby state. As will be described, each selected access unit responds to this alert signal by broadcasting a recurrent sequence of second alert signals containing respective identifiers of all standby cordless stations to notify the arrival of an incoming call, not knowing which cordless stations are within their own service area.
Therefore, as many ACK signals are returned from each access unit as there are standby cordless stations within the service area of the access unit.
Following step 44, a timer is set equal to a period of t1 seconds (step 4S) and a check is made for the presence of an acknowledgment signal (ACK) from access units 4 (step 46). If there is none, control repeats step 46 after checking for the expiration of timeout period t1 (step 47), and if there is one, exit is to step 48 to check to see if ACK signals are received from all standby cordless stations. If the answer is negative, steps 46 and 48 are repeated until the timeout period t1 expires (step 49), and if the answer is affirmative, control moves ahead to step 50 to send a proceed-to-assign signal to the selected access units, and proceeds to decision step 51 to check to see if an off-hook signal is returned from one of the selected access units. If the timeout period t1 expires at step 47, control returns to step 41 to repeat the process, and if it expires at step 49, control exits to step 51.
As will be described, the proceed-to-assign signal `--~ 2040572 allows each access unit to assign a common speech channel to the incoming call and to switch the access unit and cordless stations to the assigned speech channel so that the cordless stations can receive ringing signals from the access unit.
If the answer is negative in step 51, this step is repeated until the incoming call is abandoned from the network side of the connection (step 52), and if the answer is affirmative, control advances to step 53 to transmit a speech-circuit turn-on signal (containing in it the system identifer and the identifier of the station from which the off-hook signal has returned) to the access unit which has returned the off-hook signal, 8a ~i , ~
operates matrix switch 9 to establish a connection to trip the ringing signal 2 from the network, and transmits a proceed-to-clear signals to the other of 3 the selected access units in order to clear ringing signals supplied from it 4 to cordless stations. Following step 53, main controller 2 enters a talkings mode with respect to the incoming call.
6 In Fig. 6A, if an access unit 4 is in a standby mode, it initiates program 7 execution with step 61 to check for the presence of an alert signal from 8 main controller 2. If the answer is affirmative, exit is to step 62 to set a t2-9 second timeout period and activate the alert signal generator 1 8 to 1 0 broadcast station alert signals to all cordless stations (step 63) to elicit a 1 1 response from each station. Exit then is to step 64 which checks for the 12 presence of an ACK signal from a cordless station which responded to 13 the alert signal addressed to it. If no ACK is received within the t2-second 1 4 timeout period (steps 64 and 65), control returns to the starting point of 15 the program, recognizing that there is no standby cordless station within 16 the own service area. If the answer in step 64 is affirmative, control goes 17 to step 66 to return an ACK signal to main controller 2 and proceeds to 18 step 67 to check to see if ACK signals are received from all cordless 19 stations of the system. If the answer is negative, control exits to step 68 to 20 repeat a check for the presence of an ACK signal. If there is one, control 21 returns to step 66; otherwise, it advances to step 69 to check to see if a 22 proceed-to-assign signal is received from main controller 2. If the answer 23 iS negative, steps 68 and 69 are repeated until the timeout period t2 2 4 expires (step 70).
2 5 If the decision in step 67, 69 or 70 is affirmative, control advances to26 step 71 to deactivate the alert signal generator 18. Exit then is to step 72 27 to broadcast a channel assignment signal containing the identifier of a 2 8 speech channel to be assigned to the incoming call and the identifier of 29 the cordless station which responded with the earliest of the ACK signals ~o 2040572 from cordless stations located in the same service area. Exit then is to 2 steps 73 and 74 to set a t3-second timeout period and switch to the 3 assigned speech channel. Control proceeds to step 75 to check for the 4 reception of an end-of-switching signal from the cordless station identifiedS by the channel assignment signal. If this signal is not received within the 6 t3-second timeout period (steps 75 and 76), control returns to the starting 7 point of the program.
8 If the answer is afffirmative in step 75, exit then is to step 77 (Fig. 6B) to 9 broadcast ringing signals in sequence to those cordless stations which 1 0 returned ACK signals. To avoid undesirable effect caused by a collision 1 1 between simultaneous occurrences of call answering attempts, the ringing 12 signals contain the respective station identifiers of such cordless stations 13 by allowing only one of the stations to return an off-hook signal. Control 14 goes to step 78 to check for the presence of a proceed-to-clear signal 1 s from main controller 2. If this is the case, control exits to step 79 to 16 broadcast a clearing signal to clear the ringing signals. If the answer is 17 negative in step 78, control exits to step 80 to check for the presence of 18 an off-hook signal from a cordless station. Steps 78 and 80 are repeated 1 9 if no off-hook signal is received. If the answer is afffirmative in step 80, exit 2 0 iS to step 81 to return an off-hook signal to main controller 2 to allow it to 21 supply a turn-on signal (step 53, Fig. 5). A t4-second timeout period is 2 2 then set (step 82). Decision step 83 follows to check for the reception of a23 turn-on signal from main controller 2. Step 83 is repeated until t4-second 24 timeout period expires (step 84) and exits the loop to enter a standby state. If the answer is affirmative in step 83, step 85 is executed by 26 broadcasting a turn-on signal containing in it the identifier of the cordless 27 station which has transmitted the off-hook signal, and control enters a 28 talking mode.
29 In Fig. 7A, if a cordless station is in a standby mode, it begins its NE-335 2 ~ 5 7 2 program execution with step 90 by turning off power switch 28 to cut off 2 power supplies to transceiver (transmitter 25 and receiver 21) for battery 3 savings purposes. Exit then is to step 91 to set a t5-second timeout 4 period. Steps 92 and 93 are sequentially executed to check for the 5 expiration of the t5-second timeout period and check to see if the 6 cordless station goes off hook. If the station goes off hook or t5-second 7 period expires before the station goes off hook, control moves ahead to 8 step 94 to turn on power switch 28 to activate the transceiver, and g proceeds to step 9S to switch its frequeny synthesizers to the control 10 channel. A t6-second timeout period is then set (step 96) and the 11 presence of an off-hook condition of the cordless station is again checked 12 (step 97). If the cordless station goes off hook when step 97 is being 13 executed, the user's attempt is a call origination and control moves to a 14 call originating subroutine 100. If no off-hook condition is detected by 15 step 97, a check is made (step 98) for the presence of an output signal 16 from field intensity detector 26 indicating that an incoming call is received.
1 4 Referring now to Fig. 1, there is shown a cordless key telephone system according to the present invention. The system includes a main 16 controller 2 connected to the public telephone network 1 via three 17 subscriber lines 61 through 63, for example. Main controller 2 is further 18 connected by local lines 71~74 to access units 41~44 which are divided 19 into two groups corresponding to service areas 31 and 32 and located at 20 strategic points of the corresponding service areas. The system has four 21 cordless stations 51 through 54, for example, which may roam across the 22 boundaries between service areas 31 and 32. A two-way control channel 23 iS provided between the access units and cordless stations. During 24 standby modes, all access units and cordless stations are switched to the 2 S control channel to constantly monitor the signals carried on that channel.
26 During a call origination or termination phase, tne control channel is used 27 to exchange control signals to assign a two-way speech channel.
28 As shown in Fig. 2, main controller 2 comprises line interfaces 81~83 29 respectively coupled via subscriber lines 61-63 to the network 1, local --6 20b~7~
interfaces 101~104 respectively coupled to local lines 71-74~ and a 2 switching matrix 9 for establishing a connection between the interfaces 8 3 and 10. A control circuit 11 is coupled to all interfaces 8 and 10 to supply 4 a switching control signal to matrix 9 in a manner as will be described.
As illustrated in Fig. 3, each access unit 4k includes a hybrid 12 having 6 its two-wire circuit coupled to the associated local line 7k. The transmit 7 portion of the four-wire circuit is coupled to the input of a transmitter 13,8 the receive portion of the four-wire circuit being coupled to the output of 9 a receiver 14. The output of transmitter 13 is coupled via a duplexer 15 to 10 an antenna 16 for transmission to cordless stations. Signals received by 1 1 antenna 16 from cordless stations are coupled by duplexer 15 to the input 12 of receiver 14 for transmission to main controller 2. A frequency 1 3 synthesizer is included in transmitter 13 and receiver 14 to receive control14 signals transmitted on the control channel from both sides of the access 15 unit for coupling to a control circuit 17. In a manner to be described, 16 controJ circuit 17 processes the received control signals and generates 17 control signals for transmission to either side of the unit. An alert signal 18 generator 18 is connected to the control circuit to generate station alert 19 signals in succession to all cordless stations of the system in response to 20 an enable signal from control circuit 17. Each alert signal contains the 21 system identifier and the identifier of each cordless station. The output of 22 alert signal generator 18 is applied to transmitter 1 3 for transmission to 2 3 cordless stations.
24 In Fig. 4, signal from the nearby access unit is detected by an antenna 25 19 of each cordless station 5k and passed through a duplexer 20 to a 26 receiver 21 where it is converted to an audio-frequency signal and 27 applied through a normally open switching circuit 22 to an earphone 23.
2 8 Signal from microphone 24 is coupled through switching circuit 22 to a 29 transmitter 25 where it is converted to a high-frequency signal and applied through duplexer 20 to antenna 19. A field intensity detector 26 is connected to receiver 21 to compare the field intensity of the cordless station with a prescribed threshold and applies an output signal to a control circuit 27 if the field intensity is higher than the threshold. As will be described, control circuit 27 exchanges control signals with receiver 21 and transmitter 25 by tuning their frequency synthesizers to the control channel and switching to a speech channel when it is assigned by the communicating access unit. For power savings purposes, a power switch 28 is controlled by control circuit 27 to cut off power supplies from a battery 29 to receiver 21 and transmitter 25. A tone ringer 30 is connected to control circuit 27 to audibly alert the user upon receipt of an incoming call from the network. A keypad 31 is also connected to control circuit 27 to generate an off-hook signal when answering an incoming call or generate a connection request as well as destination address information when originating an outgoing call.
Each of the respective control circuits of main controller 2, access units 4 and cordless stations 5 is a microprocessor-based controller which is programmed to perform a stored sequence of instructions as described hereinbelow.
FLOWCHARTS
In Fig. 5, main controller 2 initiates program execution with sequential steps 41, 42 and 43 which check in succession for the presence of an incoming call from the network on one of subscriber lines 61, 62 and 63. If there is one, control proceeds to step 44 to select two access units one for each service area and send a first alert signal to both of the selected access units in order to wait for copied versions of acknowledgment (ACK) signals from cordless stations which are in a standby state. As will be described, each selected access unit responds to this alert signal by broadcasting a recurrent sequence of second alert signals containing respective identifiers of all standby cordless stations to notify the arrival of an incoming call, not knowing which cordless stations are within their own service area.
Therefore, as many ACK signals are returned from each access unit as there are standby cordless stations within the service area of the access unit.
Following step 44, a timer is set equal to a period of t1 seconds (step 4S) and a check is made for the presence of an acknowledgment signal (ACK) from access units 4 (step 46). If there is none, control repeats step 46 after checking for the expiration of timeout period t1 (step 47), and if there is one, exit is to step 48 to check to see if ACK signals are received from all standby cordless stations. If the answer is negative, steps 46 and 48 are repeated until the timeout period t1 expires (step 49), and if the answer is affirmative, control moves ahead to step 50 to send a proceed-to-assign signal to the selected access units, and proceeds to decision step 51 to check to see if an off-hook signal is returned from one of the selected access units. If the timeout period t1 expires at step 47, control returns to step 41 to repeat the process, and if it expires at step 49, control exits to step 51.
As will be described, the proceed-to-assign signal `--~ 2040572 allows each access unit to assign a common speech channel to the incoming call and to switch the access unit and cordless stations to the assigned speech channel so that the cordless stations can receive ringing signals from the access unit.
If the answer is negative in step 51, this step is repeated until the incoming call is abandoned from the network side of the connection (step 52), and if the answer is affirmative, control advances to step 53 to transmit a speech-circuit turn-on signal (containing in it the system identifer and the identifier of the station from which the off-hook signal has returned) to the access unit which has returned the off-hook signal, 8a ~i , ~
operates matrix switch 9 to establish a connection to trip the ringing signal 2 from the network, and transmits a proceed-to-clear signals to the other of 3 the selected access units in order to clear ringing signals supplied from it 4 to cordless stations. Following step 53, main controller 2 enters a talkings mode with respect to the incoming call.
6 In Fig. 6A, if an access unit 4 is in a standby mode, it initiates program 7 execution with step 61 to check for the presence of an alert signal from 8 main controller 2. If the answer is affirmative, exit is to step 62 to set a t2-9 second timeout period and activate the alert signal generator 1 8 to 1 0 broadcast station alert signals to all cordless stations (step 63) to elicit a 1 1 response from each station. Exit then is to step 64 which checks for the 12 presence of an ACK signal from a cordless station which responded to 13 the alert signal addressed to it. If no ACK is received within the t2-second 1 4 timeout period (steps 64 and 65), control returns to the starting point of 15 the program, recognizing that there is no standby cordless station within 16 the own service area. If the answer in step 64 is affirmative, control goes 17 to step 66 to return an ACK signal to main controller 2 and proceeds to 18 step 67 to check to see if ACK signals are received from all cordless 19 stations of the system. If the answer is negative, control exits to step 68 to 20 repeat a check for the presence of an ACK signal. If there is one, control 21 returns to step 66; otherwise, it advances to step 69 to check to see if a 22 proceed-to-assign signal is received from main controller 2. If the answer 23 iS negative, steps 68 and 69 are repeated until the timeout period t2 2 4 expires (step 70).
2 5 If the decision in step 67, 69 or 70 is affirmative, control advances to26 step 71 to deactivate the alert signal generator 18. Exit then is to step 72 27 to broadcast a channel assignment signal containing the identifier of a 2 8 speech channel to be assigned to the incoming call and the identifier of 29 the cordless station which responded with the earliest of the ACK signals ~o 2040572 from cordless stations located in the same service area. Exit then is to 2 steps 73 and 74 to set a t3-second timeout period and switch to the 3 assigned speech channel. Control proceeds to step 75 to check for the 4 reception of an end-of-switching signal from the cordless station identifiedS by the channel assignment signal. If this signal is not received within the 6 t3-second timeout period (steps 75 and 76), control returns to the starting 7 point of the program.
8 If the answer is afffirmative in step 75, exit then is to step 77 (Fig. 6B) to 9 broadcast ringing signals in sequence to those cordless stations which 1 0 returned ACK signals. To avoid undesirable effect caused by a collision 1 1 between simultaneous occurrences of call answering attempts, the ringing 12 signals contain the respective station identifiers of such cordless stations 13 by allowing only one of the stations to return an off-hook signal. Control 14 goes to step 78 to check for the presence of a proceed-to-clear signal 1 s from main controller 2. If this is the case, control exits to step 79 to 16 broadcast a clearing signal to clear the ringing signals. If the answer is 17 negative in step 78, control exits to step 80 to check for the presence of 18 an off-hook signal from a cordless station. Steps 78 and 80 are repeated 1 9 if no off-hook signal is received. If the answer is afffirmative in step 80, exit 2 0 iS to step 81 to return an off-hook signal to main controller 2 to allow it to 21 supply a turn-on signal (step 53, Fig. 5). A t4-second timeout period is 2 2 then set (step 82). Decision step 83 follows to check for the reception of a23 turn-on signal from main controller 2. Step 83 is repeated until t4-second 24 timeout period expires (step 84) and exits the loop to enter a standby state. If the answer is affirmative in step 83, step 85 is executed by 26 broadcasting a turn-on signal containing in it the identifier of the cordless 27 station which has transmitted the off-hook signal, and control enters a 28 talking mode.
29 In Fig. 7A, if a cordless station is in a standby mode, it begins its NE-335 2 ~ 5 7 2 program execution with step 90 by turning off power switch 28 to cut off 2 power supplies to transceiver (transmitter 25 and receiver 21) for battery 3 savings purposes. Exit then is to step 91 to set a t5-second timeout 4 period. Steps 92 and 93 are sequentially executed to check for the 5 expiration of the t5-second timeout period and check to see if the 6 cordless station goes off hook. If the station goes off hook or t5-second 7 period expires before the station goes off hook, control moves ahead to 8 step 94 to turn on power switch 28 to activate the transceiver, and g proceeds to step 9S to switch its frequeny synthesizers to the control 10 channel. A t6-second timeout period is then set (step 96) and the 11 presence of an off-hook condition of the cordless station is again checked 12 (step 97). If the cordless station goes off hook when step 97 is being 13 executed, the user's attempt is a call origination and control moves to a 14 call originating subroutine 100. If no off-hook condition is detected by 15 step 97, a check is made (step 98) for the presence of an output signal 16 from field intensity detector 26 indicating that an incoming call is received.
17 If the answer is negative in step 98, steps 97, 98 are repeated until the t6-18 second timeout period expires (step 99). If this timeout period expires, 19 control returns to the starting point of the program to repeat the battery savings process.
21 If the answer is affirmative in step 98, control exits to step 101 (Fig. 7B) 22 to set a t7-second timeout period and goes to step 102 to check for the 23 presence of a station alert signal addressed to the own key telephone 24 system. Since the system has four registered cordless stations, four 25 station alert signals are sequentially received by each cordless station. If 26 no alert signal is received following the generation of an output signal 27 from high intensity detector 26, the t7-second period will expire (step 2 8 103) and the station enters a standby mode. If an alert signal is received, 29 control exits to step 104 to set the t7-second timeout period again and NE-335 2 0 ~ O ~ 72 proceeds to step 105 to check to see if there is a match between the 2 station identifier contained in the received alert signal and the own station3 identifier. If there is no match, control returns to step 102 to repeat the 4 process. If the answer is affirmative in step 105, control exits to step 106 s to return an ACK signal to the access unit. This ACK signal contains the 6 system identifier and the identifier of the own cordless station. The 7 transmission of this ACK signal will cause the corresponding access unit to 8 deactivate the alert signal generator 26 (step 71, Fig. 6A) and broadcast a 9 channel assignment signal (step 72).
10 Exit then is to step 107 to check for the presence of an channel 11 assignment signal from the access unit. If no channel assignment signal is 12 received, control proceeds to step 108 to check for the presence of a 13 station alert signal. If any of the alert signals of the system is received, the 14 t7-second timeout period is set up again (step 109), with control returning 15 to step 107. If the decisions in steps 107 and 108 are both negative 16 during the timeout period of t7 seconds (step 110), control enters a 17 standby state.
1 8 If the decision in step 107 is affirmative, control exits to step 111 to 19 switch the frequency synthesizers of the cordless station to a speech channel indicated by the received channel assignment signal. Control 21 then moves to step 112 to check to see if the station identifier contained in 22 the channel assignment signal matches the identifier of the own cordless 2 3 station. If it is, control advances to step 1 13 to check to see if the switched 24 speech channel is in an idle state. If not, control enters a standby mode.
If the switched speech channel is idle, control exits to step 114 to return an 26 end-of switching signal to the access unit, allowing it to proceed to step 27 77 to broadcast ringing signals (Fig. 6B).
2 8 Exit then is to step 115 (Fig. 7C) to set up a tg-second timeout period 29 for successive detection of a ringing signal (step 116) and a turn-on signal NE-335 2040~
-(step 117) and a clearing signal (step 1 18) until the timeout period of t8 2 seconds expires (step 120), whereupon control returns to step 95. If the 3 turn-on signal is received (step 117) or if the clearing signal is received 4 (step 118), control proceeds to step 1 19 for deactivating the tone ringer s and returns to step 95. Steps 117 through 120 are executed by stations 6 which do not go off hook. If the ringing signal is received (step 116), 7 control proceeds to step 121 to check to see if the own station goes off 8 hook. If negative decision is made in step 1 19, control activates tone 9 ringer 30 (step 121 ) to alert the users, and returns to step 115.
10 When the station goes off hook, control exits to step 123 to 1 1 deactivate the tone ringer and proceeds to step 124 to detect a match 12 between the station identifier transmitted by the received ringing signal 13 and the own station identifier. If they fail to match, control returns to step 1 4 1 15, and if a match occurs, control proceeds to step 125 to set the timer 1 s to a timeout period of tg seconds, and proceeds to step 126 to return an 16 off-hook signal containing in it the system identifier and the identifier of 17 the cordless station. Thus, if more than one cordless station goes off 18 hook, the off-hook signal is transmitted only from one of such stations.
19 The transmission of the off-hook signal from the cordless station causes 20 the corresponding access unit to proceed to step 81 (Fig. 6B) to transmit a 21 copy of the received off-hook signal to main controller 2. On receiving 2 2 this copy of off-hook signal, main controller 2 proceeds to step 53 (Fig. 5)23 to return a turn-on signal to the access unit containing in it the system 24 identifier and the identifier of the station going off hook, as well as a 25 proceed-to-clear signal. On receiving this turn-on signal (step 83, Fig. 6B),26 the access unit broadcasts a copy of the received turn-on signal (step 85).
27 Exit then is to step 127 to check for the presence of a turn-on signal 2 8 from the access unit. If this signal is not received within the timeout period 2 9 tg (step 128), control enters a standby mode, and if it is received within this period, exits to step 129 to check for a match between the station 2 identifier contained in the turn-on signal and the own identifier. If the 3 answer is affirmative, control exits to step 130 to close the normally open 4 switching circuit 22 and enters a talking mode. If there is a mismatch, S control returns to step 9S to switch the cordless station to the control 6 channel in order to receive the next incoming call which may 7 immediately follow.
gThe operation of the system will now be described with reference to 10 the drawings described above together with Fig. 8. Assume that cordless 11 stations 51 and 52 are located in service area 31 and the other cordless 12 stations are located in service area 32 when an incoming call is received 13 on subscriber line 61 from the network and that all cordless stations are in 14 a standby state executing the battery savings steps 90 to 99.
15 The incoming call is detected by line interface 81 of main controller 2, 16and this fact is communicated to control circuit 11 (step 41, Fig. S), which --17 proceeds to select one access unit for each service area, say, access units 18 41 and 43 for service areas 31 and 32, respectively, and transmits alert 1 9 signals to the selected units (step 44) from local interfaces 1 l and 103 via 20 local lines 71 and 73. More specifically, the alert signal from local 21 interface 10l, for example, is supplied to transmitter 13 of access unit 41 22 and fed into control circuit 17 (step 61, Fig. 6A) and a recurrent sequence 23 of station alert signals 51~ S2, S3 and S4 (Fig. 8) are generated by alert 24 signal generator 18 and broadcast from transmitter 13 by antenna 16 to 25 cordless stations 51 and 52 following the setup of a t2-second timeout 26 period (steps 62 and 63). Station alert signals S1, S2, S3 and 54 27 respectively address to all cordless stations 51~ 52, 53 and 54 of the 2 8 system. Likewise, the same station alert signals are recurrently broadcast 2 9 from access unit 43 to cordless stations 53 and 54.
-If field intensity detector 26 produces a high-intensity signal (step 98, 2 Fig. 7A), the station alert signals from access unit 41 are detected by the 3 antenna 19 and supplied through receiver 21 of each cordless station to 4 control circuit 27 in which their station identifiers are compared with the s identifier of the own station to detect a match between them (steps 6 102-105, Fig. 7B). When there is a match (step 105), an 7 acknowledgment (ACK) signal T31 is transmitted (step 106) from 8 transmitter 25 by antenna 19 of station 53 to access unit 43 and ACK
9 signal T41 is transmitted in succession from station 54 to access unit 43. In 10 a similar manner, ACK signal T11 is transmitted from station 51 to access 1 1 unit 41 and ACK signal T21 is transmitted in succession to access unit 41-12 ACK signals T1 1~ T21, T31 and T41 contain the system identifier and the 13 respective station identifiers as described above.
14 ACK signals T1 1 and T21 are received by the receiver 14 of access 15 unit 41 and supplied to its control circuit 17 in which they are examined to 16 see if they contain the same system identifier as that of the own key 17 telephone system (step 64, Fig. 6A). Likewise, ACK signals T31 and T41 18 are received and examined by access unit 43. In response to ACK signal 19 T1 1~ a copy of this signal is returned from access unit 41 to main controller 20 2 as an ACK signal T12 (step 66) and in response to the next ACK signal 21 T21, a copy of this signal is returned from access unit 41 to main controller22 2 as an ACK signal T22 (steps 67, 68 and 66) to wait for the reception of a 23 proceed-to-assign signal from main controller 2 (step 69). In a similar 24 manner, a copy T32 of ACK signal T31 and a copy T42 of ACK signal T
25 are successively returned from access unit 43 to wait for the proceed-to-26 assign signal. Note that the order of ACK signals returning from cordless 27 stations may vary depending on the independent timing of their battery 28 savings operations, so that under certain circumstances ACK signal T
21 If the answer is affirmative in step 98, control exits to step 101 (Fig. 7B) 22 to set a t7-second timeout period and goes to step 102 to check for the 23 presence of a station alert signal addressed to the own key telephone 24 system. Since the system has four registered cordless stations, four 25 station alert signals are sequentially received by each cordless station. If 26 no alert signal is received following the generation of an output signal 27 from high intensity detector 26, the t7-second period will expire (step 2 8 103) and the station enters a standby mode. If an alert signal is received, 29 control exits to step 104 to set the t7-second timeout period again and NE-335 2 0 ~ O ~ 72 proceeds to step 105 to check to see if there is a match between the 2 station identifier contained in the received alert signal and the own station3 identifier. If there is no match, control returns to step 102 to repeat the 4 process. If the answer is affirmative in step 105, control exits to step 106 s to return an ACK signal to the access unit. This ACK signal contains the 6 system identifier and the identifier of the own cordless station. The 7 transmission of this ACK signal will cause the corresponding access unit to 8 deactivate the alert signal generator 26 (step 71, Fig. 6A) and broadcast a 9 channel assignment signal (step 72).
10 Exit then is to step 107 to check for the presence of an channel 11 assignment signal from the access unit. If no channel assignment signal is 12 received, control proceeds to step 108 to check for the presence of a 13 station alert signal. If any of the alert signals of the system is received, the 14 t7-second timeout period is set up again (step 109), with control returning 15 to step 107. If the decisions in steps 107 and 108 are both negative 16 during the timeout period of t7 seconds (step 110), control enters a 17 standby state.
1 8 If the decision in step 107 is affirmative, control exits to step 111 to 19 switch the frequency synthesizers of the cordless station to a speech channel indicated by the received channel assignment signal. Control 21 then moves to step 112 to check to see if the station identifier contained in 22 the channel assignment signal matches the identifier of the own cordless 2 3 station. If it is, control advances to step 1 13 to check to see if the switched 24 speech channel is in an idle state. If not, control enters a standby mode.
If the switched speech channel is idle, control exits to step 114 to return an 26 end-of switching signal to the access unit, allowing it to proceed to step 27 77 to broadcast ringing signals (Fig. 6B).
2 8 Exit then is to step 115 (Fig. 7C) to set up a tg-second timeout period 29 for successive detection of a ringing signal (step 116) and a turn-on signal NE-335 2040~
-(step 117) and a clearing signal (step 1 18) until the timeout period of t8 2 seconds expires (step 120), whereupon control returns to step 95. If the 3 turn-on signal is received (step 117) or if the clearing signal is received 4 (step 118), control proceeds to step 1 19 for deactivating the tone ringer s and returns to step 95. Steps 117 through 120 are executed by stations 6 which do not go off hook. If the ringing signal is received (step 116), 7 control proceeds to step 121 to check to see if the own station goes off 8 hook. If negative decision is made in step 1 19, control activates tone 9 ringer 30 (step 121 ) to alert the users, and returns to step 115.
10 When the station goes off hook, control exits to step 123 to 1 1 deactivate the tone ringer and proceeds to step 124 to detect a match 12 between the station identifier transmitted by the received ringing signal 13 and the own station identifier. If they fail to match, control returns to step 1 4 1 15, and if a match occurs, control proceeds to step 125 to set the timer 1 s to a timeout period of tg seconds, and proceeds to step 126 to return an 16 off-hook signal containing in it the system identifier and the identifier of 17 the cordless station. Thus, if more than one cordless station goes off 18 hook, the off-hook signal is transmitted only from one of such stations.
19 The transmission of the off-hook signal from the cordless station causes 20 the corresponding access unit to proceed to step 81 (Fig. 6B) to transmit a 21 copy of the received off-hook signal to main controller 2. On receiving 2 2 this copy of off-hook signal, main controller 2 proceeds to step 53 (Fig. 5)23 to return a turn-on signal to the access unit containing in it the system 24 identifier and the identifier of the station going off hook, as well as a 25 proceed-to-clear signal. On receiving this turn-on signal (step 83, Fig. 6B),26 the access unit broadcasts a copy of the received turn-on signal (step 85).
27 Exit then is to step 127 to check for the presence of a turn-on signal 2 8 from the access unit. If this signal is not received within the timeout period 2 9 tg (step 128), control enters a standby mode, and if it is received within this period, exits to step 129 to check for a match between the station 2 identifier contained in the turn-on signal and the own identifier. If the 3 answer is affirmative, control exits to step 130 to close the normally open 4 switching circuit 22 and enters a talking mode. If there is a mismatch, S control returns to step 9S to switch the cordless station to the control 6 channel in order to receive the next incoming call which may 7 immediately follow.
gThe operation of the system will now be described with reference to 10 the drawings described above together with Fig. 8. Assume that cordless 11 stations 51 and 52 are located in service area 31 and the other cordless 12 stations are located in service area 32 when an incoming call is received 13 on subscriber line 61 from the network and that all cordless stations are in 14 a standby state executing the battery savings steps 90 to 99.
15 The incoming call is detected by line interface 81 of main controller 2, 16and this fact is communicated to control circuit 11 (step 41, Fig. S), which --17 proceeds to select one access unit for each service area, say, access units 18 41 and 43 for service areas 31 and 32, respectively, and transmits alert 1 9 signals to the selected units (step 44) from local interfaces 1 l and 103 via 20 local lines 71 and 73. More specifically, the alert signal from local 21 interface 10l, for example, is supplied to transmitter 13 of access unit 41 22 and fed into control circuit 17 (step 61, Fig. 6A) and a recurrent sequence 23 of station alert signals 51~ S2, S3 and S4 (Fig. 8) are generated by alert 24 signal generator 18 and broadcast from transmitter 13 by antenna 16 to 25 cordless stations 51 and 52 following the setup of a t2-second timeout 26 period (steps 62 and 63). Station alert signals S1, S2, S3 and 54 27 respectively address to all cordless stations 51~ 52, 53 and 54 of the 2 8 system. Likewise, the same station alert signals are recurrently broadcast 2 9 from access unit 43 to cordless stations 53 and 54.
-If field intensity detector 26 produces a high-intensity signal (step 98, 2 Fig. 7A), the station alert signals from access unit 41 are detected by the 3 antenna 19 and supplied through receiver 21 of each cordless station to 4 control circuit 27 in which their station identifiers are compared with the s identifier of the own station to detect a match between them (steps 6 102-105, Fig. 7B). When there is a match (step 105), an 7 acknowledgment (ACK) signal T31 is transmitted (step 106) from 8 transmitter 25 by antenna 19 of station 53 to access unit 43 and ACK
9 signal T41 is transmitted in succession from station 54 to access unit 43. In 10 a similar manner, ACK signal T11 is transmitted from station 51 to access 1 1 unit 41 and ACK signal T21 is transmitted in succession to access unit 41-12 ACK signals T1 1~ T21, T31 and T41 contain the system identifier and the 13 respective station identifiers as described above.
14 ACK signals T1 1 and T21 are received by the receiver 14 of access 15 unit 41 and supplied to its control circuit 17 in which they are examined to 16 see if they contain the same system identifier as that of the own key 17 telephone system (step 64, Fig. 6A). Likewise, ACK signals T31 and T41 18 are received and examined by access unit 43. In response to ACK signal 19 T1 1~ a copy of this signal is returned from access unit 41 to main controller 20 2 as an ACK signal T12 (step 66) and in response to the next ACK signal 21 T21, a copy of this signal is returned from access unit 41 to main controller22 2 as an ACK signal T22 (steps 67, 68 and 66) to wait for the reception of a 23 proceed-to-assign signal from main controller 2 (step 69). In a similar 24 manner, a copy T32 of ACK signal T31 and a copy T42 of ACK signal T
25 are successively returned from access unit 43 to wait for the proceed-to-26 assign signal. Note that the order of ACK signals returning from cordless 27 stations may vary depending on the independent timing of their battery 28 savings operations, so that under certain circumstances ACK signal T
29 may arrive first in response to a first sequence of alert signals and T
may arrive last in response to a second sequence of alert signals.
2 On receiving ACK signals from all standby cordless stations (step 48, 3 Fig. 5), main controller 2 sends a proceed-to-assign signal to the selected 4 access units 41 and 43 (step 50).
It is seen that, since the proceed-to-assign signal is generated at the 6 instant when ACK signals corresponding to those from all cordless 7 stations are received by main controller 2, the call terminating process can 8 proceed further to promptly answer the incoming call.
9 In response to the proceed-to-assign signal (step 69, Fig. 6A), access 10 units 41 and 43 turn off their alert signal generator 18 (step 71 ) and 11 broadcast a channel assignment signal (step 72) containing an assigned 12 speech-channel identifier and the identifier of a cordless station which 13 returned the ACK signal of the earliest arrival in each service area, (i.e., 14 station 51 for access unit 41 and station 53 for access unit 43), switch to the 1 S assigned speech channel (step 74). Access unit 41 now waits for an end-16 of-switching signal from cordless station 51 (step 75) during timeout 17 period t3 and access unit 43 waits for an end-of-switching signal from 18 cordless station 53.
19 On receiving the channel assignment signal from access unit 41 (step 20 107, Fig. 7B), cordless stations 51 and 52 switch to the assigned speech 2 1 channel (step 111 ) and checks to see if the station identifier contained in 22 the channel assignment signal matches the own station identifiers (step 2 3 1 12). Thus, cordless station 51 exits to step 11 3 to check to see if the 24 assigned channel is idle, and if it is, returns an end-of-switching signal to 2 5 access unit 41 (step 1 14). After setting timeout period tg, cordless stations 2 6 51 and 52 wait for a ringing signal from access unit 41 (steps 115 and 116, 27 Fig. 7C). Likewise, cordless stations 53 and 54 switch to the assigned 28 speech channel in response to the channel assignment signal. Station 53 29 returns an end-of-switchlng signal to access unit 43 (step 114). Stations 53 NE-335 20~0572 and 54 wait for respective ringing signals from access unit 43 after setting 2 timeout period t8-3 In response to the respective end-of-switching signals from cordless 4 stations 51 and 53 (step 75, Fig. 6A), access units 41 and 43 broadcast ringing signals each containing the system identifier and the respective 6 station identifier (step 77, Fig. 6B), so that ringing signals V1 and V2 are 7 transmitted to cordless stations 51 and 52, respectively, and ringing signals 8 V3 and V4 are transmitted to cordless stations 53 and 54, respectively.
9 In response to each ringing signal, each cordless station activates ik tone ringer 30 to alert the user (steps 116, 121 and 122, Fig. 7C). If 1 1 cordless station 51 goes off hook (step 121), it turns off its tone ringer12 (step 123), detects a match between the station identifier contained in the 13 ringing signal and the own station identifier (step 124), and returns an off-14 hook signal W1 1 to access unit 41 (step 126) to wait for a turn-on signal.
On receiving the off-hook signal W11 (steps 78 and 80, Fig. 6B), 16 access unit 41 returns a copy of the off-hook signal W11 as an off-hook 1 7 signal W12 to main controller 2 (step 81).
18 Main controller 2 responds to the off-hook signal W21 by returning a 19 turn-on signal X1 1 (steps 51 and 53, Fig. 5) to access unit 41 and operating the switch 9 to establish a connection between line interface 81 and local 21 interface 11, while transmitting a proceed-to-clear signal to access unit22 43.
2 3 In response to the turn-on signal X11 (step 83, Fig. 6B), access unit 4 24 broadcasts a copy X1 2 Of the turn-on signal X1 1 (step 85) to enter a talking mode. Cordless station 51 responds to this signal (step 127, Fig.
26 7C) by detecting a match between the station identifier contained in it and27 the own identifier (step 129) and turning on the switching circuit 22 to 2 8 activate its speech circuit (step 130). Cordless station 52 responds to turn-29 on signal X12 when executing step 117 and turns off its tone ringer (step 119) leaving its switching circuit 22 in the off-state, and switches to the 2 control channel (step 95) to receive the next incoming call which may 3 immediately follow.
4 On the other hand, access unit 43 broadcasts a clearing signal in s response to proceed-to-clear signal (steps 78 and 79, Fig. 6B) and enters 6 a standby state. Cordless stations 53 and 54 receive the clearing signal 7 (step 118) and turns off their tone ringer (step 119) and switch to the 8 control channel (step 95) to receive the next incoming call.
9 It is seen that when the incoming call is answered the standby 0 cordless stations other than the station answering the call- are switched to the control channel, rather than entering the battery savings routine, the 12 system can quickly respond to the next incoming call which is handled by 13 the access units other than that involved in establishing the previous call.
14 The foregoing description shows only one preferred embodiment of 15 the present invention. Various modifications are apparent to those skilled 6 in the art without departing from the scope of the present invention which 17 is only limited by the appended claims. Therefore, the embodiment 18 shown and described is only illustrative, not restrictive.
may arrive last in response to a second sequence of alert signals.
2 On receiving ACK signals from all standby cordless stations (step 48, 3 Fig. 5), main controller 2 sends a proceed-to-assign signal to the selected 4 access units 41 and 43 (step 50).
It is seen that, since the proceed-to-assign signal is generated at the 6 instant when ACK signals corresponding to those from all cordless 7 stations are received by main controller 2, the call terminating process can 8 proceed further to promptly answer the incoming call.
9 In response to the proceed-to-assign signal (step 69, Fig. 6A), access 10 units 41 and 43 turn off their alert signal generator 18 (step 71 ) and 11 broadcast a channel assignment signal (step 72) containing an assigned 12 speech-channel identifier and the identifier of a cordless station which 13 returned the ACK signal of the earliest arrival in each service area, (i.e., 14 station 51 for access unit 41 and station 53 for access unit 43), switch to the 1 S assigned speech channel (step 74). Access unit 41 now waits for an end-16 of-switching signal from cordless station 51 (step 75) during timeout 17 period t3 and access unit 43 waits for an end-of-switching signal from 18 cordless station 53.
19 On receiving the channel assignment signal from access unit 41 (step 20 107, Fig. 7B), cordless stations 51 and 52 switch to the assigned speech 2 1 channel (step 111 ) and checks to see if the station identifier contained in 22 the channel assignment signal matches the own station identifiers (step 2 3 1 12). Thus, cordless station 51 exits to step 11 3 to check to see if the 24 assigned channel is idle, and if it is, returns an end-of-switching signal to 2 5 access unit 41 (step 1 14). After setting timeout period tg, cordless stations 2 6 51 and 52 wait for a ringing signal from access unit 41 (steps 115 and 116, 27 Fig. 7C). Likewise, cordless stations 53 and 54 switch to the assigned 28 speech channel in response to the channel assignment signal. Station 53 29 returns an end-of-switchlng signal to access unit 43 (step 114). Stations 53 NE-335 20~0572 and 54 wait for respective ringing signals from access unit 43 after setting 2 timeout period t8-3 In response to the respective end-of-switching signals from cordless 4 stations 51 and 53 (step 75, Fig. 6A), access units 41 and 43 broadcast ringing signals each containing the system identifier and the respective 6 station identifier (step 77, Fig. 6B), so that ringing signals V1 and V2 are 7 transmitted to cordless stations 51 and 52, respectively, and ringing signals 8 V3 and V4 are transmitted to cordless stations 53 and 54, respectively.
9 In response to each ringing signal, each cordless station activates ik tone ringer 30 to alert the user (steps 116, 121 and 122, Fig. 7C). If 1 1 cordless station 51 goes off hook (step 121), it turns off its tone ringer12 (step 123), detects a match between the station identifier contained in the 13 ringing signal and the own station identifier (step 124), and returns an off-14 hook signal W1 1 to access unit 41 (step 126) to wait for a turn-on signal.
On receiving the off-hook signal W11 (steps 78 and 80, Fig. 6B), 16 access unit 41 returns a copy of the off-hook signal W11 as an off-hook 1 7 signal W12 to main controller 2 (step 81).
18 Main controller 2 responds to the off-hook signal W21 by returning a 19 turn-on signal X1 1 (steps 51 and 53, Fig. 5) to access unit 41 and operating the switch 9 to establish a connection between line interface 81 and local 21 interface 11, while transmitting a proceed-to-clear signal to access unit22 43.
2 3 In response to the turn-on signal X11 (step 83, Fig. 6B), access unit 4 24 broadcasts a copy X1 2 Of the turn-on signal X1 1 (step 85) to enter a talking mode. Cordless station 51 responds to this signal (step 127, Fig.
26 7C) by detecting a match between the station identifier contained in it and27 the own identifier (step 129) and turning on the switching circuit 22 to 2 8 activate its speech circuit (step 130). Cordless station 52 responds to turn-29 on signal X12 when executing step 117 and turns off its tone ringer (step 119) leaving its switching circuit 22 in the off-state, and switches to the 2 control channel (step 95) to receive the next incoming call which may 3 immediately follow.
4 On the other hand, access unit 43 broadcasts a clearing signal in s response to proceed-to-clear signal (steps 78 and 79, Fig. 6B) and enters 6 a standby state. Cordless stations 53 and 54 receive the clearing signal 7 (step 118) and turns off their tone ringer (step 119) and switch to the 8 control channel (step 95) to receive the next incoming call.
9 It is seen that when the incoming call is answered the standby 0 cordless stations other than the station answering the call- are switched to the control channel, rather than entering the battery savings routine, the 12 system can quickly respond to the next incoming call which is handled by 13 the access units other than that involved in establishing the previous call.
14 The foregoing description shows only one preferred embodiment of 15 the present invention. Various modifications are apparent to those skilled 6 in the art without departing from the scope of the present invention which 17 is only limited by the appended claims. Therefore, the embodiment 18 shown and described is only illustrative, not restrictive.
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A cordless key telephone system for covering a plurality of service areas in which cordless stations are located, comprising: a plurality of access units divided into groups corresponding respectively to said service areas, the access units of each group being located in the corresponding service area for broadcasting signals on a two-way control channel or on an assigned two-way speech channel; a main controller coupled to a switched telephone network for selecting one of the access units for each of said service areas in response to an incoming call from said network and transmitting a first alert signal to the selected access units; each of said access units being responsive to said first alert signal for broadcasting over the control channel a recurrent sequence of second alert signals respectively identifying standby cordless stations, responsive to receipt of an acknowledgment signal from the cordless stations for transmitting a copy of the acknowledgment signal to said main controller, responsive to receipt of a proceed-to-assign signal from said main controller for broadcasting over the control channel a channel assignment signal identifying an assigned speech channel, responsive to receipt of an end-of-switching signal from the cordless stations for sequentially broadcasting over the assigned speech channel ringing signals respectively identifying the cordless stations which returned said acknowledgment signals, responsive to an off-hook signal from a replying cordless station for transmitting a copy of the off-hook signal to said main controller, and responsive to receipt of a turn-on signal from said main controller identifying the replying cordless station for broadcasting over the assigned speech channel a copy of said turn-on signal, said main controller transmitting said proceed-to-assign signal if the number of the copies of the acknowledgment signals from said selected access units is equal to the number of all standby cordless stations, and transmitting said turn-on signal to one of the selected access units if said copy of the off-hook signal is received therefrom, each of said cordless stations being responsive to the second alert signal identifying the cordless station for transmitting over the control channel said acknowledgment signal, responsive to the channel assignment signal for transmitting over the assigned speech channel said end-of-switching signal, responsive to the cordless station going off hook in response to the ringing signal identifying the cordless station for transmitting over the assigned speech channel said off-hook signal, and responsive to said copy of turn-on signal identifying the cordless station for establishing a speech circuit.
2. A cordless key telephone system as claimed in claim 1, wherein each of said cordless stations comprises means for switching the cordless station from the assigned speech channel to the control channel for a prescribed period of time in response to receipt of said broadcast copy of the turn-on signal not identifying the cordless station and periodically turning off power supplies to power draining units thereof following the end of said prescribed period.
3. A cordless key telephone system as claimed in claim 2, wherein said main controller comprises means responsive to said copy of the off-hook signal from said one of the selected access units for transmitting a proceed-to-clear signal to the other selected access units, wherein each of said access units comprises means responsive to said proceed-to-clear signal for broadcasting clearing signals respectively identifying the cordless stations not going off hook, and wherein each of the cordless stations comprises means responsive to the clearing signal identifying the cordless station for switching the cordless station from the assigned speech channel to the control channel for a prescribed period of time and periodically turning off power supplies to power draining units thereof following the end of said prescribed period.
4. In a cordless key telephone system having a plurality of access units divided into groups corresponding respectively to service areas for broadcasting radio signals on a two-way control channel or on an assigned two-way speech channel, a plurality of cordless stations, and a main controller coupled to a switched telephone network for selecting one of the access units for each of said service areas in response to an incoming call from said network and transmitting a first alert signal to the selected access units, a method comprising the steps of: a) receiving said first alert signal and, in response thereto, broadcasting from the selected access units a recurrent sequence of second alert signals over the control channel, the second alert signals respectively identifying standby cordless stations; b) receiving the second alert signal and, in response thereto, transmitting an acknowledgment signal over the control channel from each cordless station if the received second alert signal identifies the cordless station; c) receiving the acknowledgment signal and, in response thereto, transmitting a copy thereof from each of the selected access units to said main controller; d) receiving said copy of the acknowledgment signal from the selected access units and, in response thereto, transmitting a proceed-to-assign signal from said main controller to said selected access units if the number of the received copies of the acknowledgement signals is equal to the number of all standby cordless stations; e) receiving said proceed-to-assign signal and, in response thereto, broadcasting a channel assignment signal over the control channel from said selected access units, said channel assignment signal identifying said assigned speech channel; f) receiving said channel assignment signal and, in response thereto, transmitting an end-of-switching signal over the assigned speech channel from one of the cordless stations which are located in each of said areas; g) receiving said end-of-switching signal and, in response thereto, broadcasting from each of the selected access units ringing signals over the assigned speech channel, the ringing signals respectively identifying the cordless stations which have transmitted said acknowledgment signals; h) receiving the ringing signal and, in response thereto, generating a ringing tone in each cordless station if the received signal identifies the cordless station and allowing an off-hook signal to be transmitted over the assigned speech channel from a replying cordless station; i) receiving the off-hook signal and, in response thereto, transmitting a copy thereof from one of the selected access units to said main controller; j) returning a turn-on signal from the main controller as a response to said copy of the off-hook signal, said turn-on signal identifying the replying cordless station;
k) receiving said turn-on signal and, in response thereto, broadcasting a copy thereof from said access unit; and 1) causing said replying cordless station to receive said copy of the turn-on signal and establish a speech circuit thereof.
k) receiving said turn-on signal and, in response thereto, broadcasting a copy thereof from said access unit; and 1) causing said replying cordless station to receive said copy of the turn-on signal and establish a speech circuit thereof.
5. A method as claimed in claim 4, wherein the step (1) comprises switching the cordless station from the assigned speech channel to the control channel for a prescribed period of time if said received copy of the turn-on signal does not contain the identifier of the station and periodically turning off power supplies to power draining units thereof following the end of said prescribed period.
6. A method as claimed in claim 5, wherein the step (j) comprises receiving said copy of the off-hook signal from one of the selected access units and transmitting a proceed-to-clear signal from said main controller to the other selected access units, wherein the step (k) comprises the steps of receiving said proceed-to-clear signal and, in response thereto, broadcasting clearing signals respectively identifying the cordless stations not going off hook, and wherein the step (1) comprises receiving the clearing signal, and, in response thereto, switching the station from the assigned speech channel to the control channel for a prescribed period of time and periodically turning off power supplies to power draining units thereof following the end of said prescribed period.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2099416A JP2571297B2 (en) | 1990-04-17 | 1990-04-17 | Wireless telephone equipment |
| JP2-99416 | 1990-04-17 | ||
| JP2197200A JP2919011B2 (en) | 1990-07-25 | 1990-07-25 | Receiving method of wireless telephone device |
| JP2-197200 | 1990-07-25 |
Publications (1)
| Publication Number | Publication Date |
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| CA2040572C true CA2040572C (en) | 1995-02-07 |
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| Application Number | Title | Priority Date | Filing Date |
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| CA002040572A Expired - Fee Related CA2040572C (en) | 1990-04-17 | 1991-04-16 | Cordless key telephone system capable of quickly answering incoming calls |
Country Status (6)
| Country | Link |
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| US (1) | US5239572A (en) |
| EP (1) | EP0452877B1 (en) |
| KR (1) | KR940010209B1 (en) |
| AU (1) | AU636736B2 (en) |
| CA (1) | CA2040572C (en) |
| DE (1) | DE69116920T2 (en) |
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| EP0452872B1 (en) * | 1990-04-17 | 1996-08-21 | Nec Corporation | Cordless key telephone system for covering multiple service areas having exclusively assigned control channels |
| WO1992007434A1 (en) | 1990-10-23 | 1992-04-30 | Omnipoint Corporation | Method and apparatus for establishing spread spectrum communications |
| US5285469A (en) | 1991-06-03 | 1994-02-08 | Omnipoint Data Corporation | Spread spectrum wireless telephone system |
| DE4137820A1 (en) * | 1991-11-16 | 1993-05-19 | Bosch Gmbh Robert | CALLING FOR A CORDLESS TELEPHONE |
| US5363426A (en) * | 1992-07-06 | 1994-11-08 | Motorola, Inc. | Extended range paging for a radio frequency communication system |
| US5345500A (en) * | 1992-07-13 | 1994-09-06 | Motorola, Inc. | Method and apparatus for completing inbound calls in a wireless communication system |
| GB9302846D0 (en) * | 1993-02-12 | 1993-03-31 | Shaye Communications Ltd | Improvements relating to communications systems |
| US6005856A (en) * | 1993-11-01 | 1999-12-21 | Omnipoint Corporation | Communication protocol for spread spectrum wireless communication system |
| US6094575A (en) | 1993-11-01 | 2000-07-25 | Omnipoint Corporation | Communication system and method |
| US6301242B1 (en) | 1998-07-24 | 2001-10-09 | Xircom Wireless, Inc. | Communication system with fast control traffic |
| US6088590A (en) | 1993-11-01 | 2000-07-11 | Omnipoint Corporation | Method and system for mobile controlled handoff and link maintenance in spread spectrum communication |
| JP2846815B2 (en) * | 1994-05-18 | 1999-01-13 | キヤノン株式会社 | Telephone equipment |
| US6775531B1 (en) | 1994-07-21 | 2004-08-10 | Interdigital Technology Corporation | Subscriber terminal temperature regulation |
| ES2255474T3 (en) * | 1994-07-21 | 2006-07-01 | Interdigital Technology Corporation | METHOD AND APPARATUS OF CONTROL OF ENERGY CONSUMPTION OF A SUBSCRIBER UNIT OF A COMMUNICATIONS SYSTEM. |
| JP3227318B2 (en) * | 1994-11-01 | 2001-11-12 | キヤノン株式会社 | Wireless telephone equipment |
| CN1090437C (en) * | 1995-04-04 | 2002-09-04 | 艾利森公司 | Mobile station user group operation |
| US5745484A (en) * | 1995-06-05 | 1998-04-28 | Omnipoint Corporation | Efficient communication system using time division multiplexing and timing adjustment control |
| US6356607B1 (en) | 1995-06-05 | 2002-03-12 | Omnipoint Corporation | Preamble code structure and detection method and apparatus |
| US6041046A (en) * | 1995-07-14 | 2000-03-21 | Omnipoint Corporation | Cyclic time hopping in time division multiple access communication system |
| US6141373A (en) * | 1996-11-15 | 2000-10-31 | Omnipoint Corporation | Preamble code structure and detection method and apparatus |
| JPH10327466A (en) * | 1997-05-26 | 1998-12-08 | Toshiba Corp | Incoming call control method and device in mobile communication equipment |
| US6377811B1 (en) | 1998-09-28 | 2002-04-23 | Sharp Laboratories Of America, Inc. | Wireless communications system and method of virtual line/direct station selection |
| DE10008241A1 (en) * | 2000-02-23 | 2001-09-20 | Siemens Ag | Call signalling in telecommunications system between base station and mobile element enables call signalling from number of mobiles associated with base station - involves base station sequentially contacting mobiles over temporary radio links on receiving incoming connection request from telecommunications network |
| JP2003284143A (en) * | 2002-03-20 | 2003-10-03 | Sharp Corp | Phone communication apparatus |
| WO2006010958A2 (en) | 2004-07-30 | 2006-02-02 | Andrew Richardson | Power control in a local network node (lnn) |
| EP1779543B1 (en) * | 2004-07-30 | 2012-04-25 | Andrew Richardson | Signal transmission method from a local network node |
| JP4207005B2 (en) * | 2005-01-28 | 2009-01-14 | ブラザー工業株式会社 | Cordless equipment |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0260991A3 (en) * | 1986-09-18 | 1990-01-17 | Sony Corporation | Radio communication system and method |
| CA1288822C (en) * | 1987-05-29 | 1991-09-10 | Yoshitoshi Murata | Radio communication network system comprising a connecting equipment unit operable in different modes |
| JP2516983B2 (en) * | 1987-06-19 | 1996-07-24 | 松下通信工業株式会社 | Wireless telephone equipment |
| JP2642380B2 (en) * | 1988-02-16 | 1997-08-20 | 日本電信電話株式会社 | Wireless communication device |
| AT393578B (en) * | 1988-05-20 | 1991-11-11 | Siemens Ag Oesterreich | METHOD FOR SETTING UP A CONNECTION BETWEEN A FIXED AND MULTIPLE MOBILE COMPONENTS OF A CORDLESS TELEPHONE SYSTEM |
| US5014295A (en) * | 1988-10-28 | 1991-05-07 | Sony Corporation | Multi-channel access cordless telephone system |
| US5005014A (en) * | 1989-05-22 | 1991-04-02 | Motorola, Inc. | System and method for optimally transmitting acknowledge back responses |
| JP2806591B2 (en) * | 1990-02-08 | 1998-09-30 | 日本電気株式会社 | Receiving method of wireless telephone system |
| EP0452872B1 (en) * | 1990-04-17 | 1996-08-21 | Nec Corporation | Cordless key telephone system for covering multiple service areas having exclusively assigned control channels |
-
1991
- 1991-04-16 AU AU75106/91A patent/AU636736B2/en not_active Ceased
- 1991-04-16 KR KR1019910006079A patent/KR940010209B1/en not_active IP Right Cessation
- 1991-04-16 DE DE69116920T patent/DE69116920T2/en not_active Expired - Fee Related
- 1991-04-16 CA CA002040572A patent/CA2040572C/en not_active Expired - Fee Related
- 1991-04-16 EP EP91106044A patent/EP0452877B1/en not_active Expired - Lifetime
- 1991-04-17 US US07/686,468 patent/US5239572A/en not_active Expired - Lifetime
Also Published As
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|---|---|
| EP0452877A3 (en) | 1992-08-12 |
| US5239572A (en) | 1993-08-24 |
| EP0452877A2 (en) | 1991-10-23 |
| KR910019467A (en) | 1991-11-30 |
| EP0452877B1 (en) | 1996-02-07 |
| DE69116920D1 (en) | 1996-03-21 |
| AU7510691A (en) | 1991-10-24 |
| AU636736B2 (en) | 1993-05-06 |
| DE69116920T2 (en) | 1996-07-04 |
| KR940010209B1 (en) | 1994-10-22 |
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