Portable wireless communication systems

• US 4,881,271 A
• Filed: 02/09/1988
• Issued: 11/14/1989
• Est. Priority Date: 03/20/1987
• Status: Expired due to Term

• Current Assignee: FIPA Frohwitter Intellectual Property AG
• Original Assignee: Hitachi, Ltd.
• Inventors: Yamauchi, Yukiji, Tsukamoto, Nobuo, Koya, Masahiro
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Kuntz, Curtis
• Application Number:
  US07/153,906
• Time in Patent Office: 644 Days
• Field of Search: 455/33, 455/56, 455/54, 455/89, 455/11, 455/34, 455/53, 455/67, 455/88, 455/90, 455/226, 379/56, 379/58-60, 379/89, 379/90, 379/225
• US Class Current: 455/436
• CPC Class Codes: H04W 72/27 between access points
• CPC Class Codes: H04W 84/16 WPBX [Wireless Private Branch Exchange]
• CPC Class Codes: H04W 92/20 between access points

Abstract

In portable wireless communication systems wherein subscriber stations communicate with a plurality of base stations each covering a predetermined area, communication lines are provided for dedicating to the exchange of the use status and observation result of radio channels with the plurality of base stations in order that each base station can autonomically manage the determination of a base station with which a subscriber station communicates, the selection of a radio channel to be used, and the like.

Claims

1. A wireless communication system comprising:

a plurality of base stations each disposed to cover a predetermined area for wireless communications;

a subscriber station movable within any of said predetermined areas and capable of communicating via radio propagation with the base station covering said predetermined area when said subscriber is positioned therein;

a dedicated line provided between adjacent base stations for exchanging information regarding the status of communication by the respective adjacent base stations;

radio exchange means connected between said base stations and other communication systems for exchanging communication between said other communication systems and any of said base stations;

wherein each of said base stations further comprises means for storing control information including information of status of communication by that base station and information of status of communication of adjacent base stations communicated through said dedicated lines, judging means for determining when a call from the subscriber station is received whether the base station covering the predetermined area into which the subscriber station has moved should respond to the call based on the control information stored in said storing means, and means responsive to said judging means having determined that said call should be responded to by one of said base station for selecting a radio channel by which said subscriber station performs communication based on said control information.

2. A wireless communication system according to claim 1, wherein said control information stored in each of the base stations includes at least:

an identification number for the selected base station;

a channel number indicating each of the radio channels assigned to each of the base stations which are presently used by said selected base station; and

a channel number indicating each of those channels, among the assigned channels, which are used by any of the adjacent base stations and not allowed to be used by said selected base stations.

3. A wireless communication system according to claim 1, wherein said dedicated line is a radio channel.

4. A wireless communication system according to claim 3, wherein said each of the base stations comprises means for measuring the strength of a signal conveying said control information of each of the adjacent base stations connected through the associated radio channel, the measured strength of the signal being used for weighting the information of each of the adjacent base stations as communicated.

5. A wireless communication system according to claim 1, wherein said dedicated line is a wire.

6. A wireless communication system according to claim 1, wherein said other communication system includes a private branch exchange connected to said exchange means and wire telephone sets present in said pre-determined area.

7. A wireless communication method for performing communication between a radio transceiver and any of a plurality of base stations disposed so as to cover a predetermined area for wireless communication via a selected one of a plurality of radio channels assigned to each of said base stations, said method comprising the steps, carried out by each of the base stations, of:

checking the status of the radio channels of a base station and storing the checked status as internal information;

transmitting the internal information of said base station to adjacent base stations and receiving the internal information of each of said adjacent base stations via a dedicated line provided between said base station and said adjacent base station, and storing said received internal information of said adjacent base stations together with the internal information of said base station, as control information;

judging in response to a received call from said radio transceiver whether said base station should respond to the call or not based on the stored control information;

selecting on the basis of said response one of said radio channels of said selected base stations for communication with the radio transceiver; and

performing communication with the radio transceiver through the selected radio channel.

8. A wireless communication method according to claim 7, wherein said control information includes an identifier number of that base station and information of each of the radio channels as to whether the radio channel is used by any of the adjacent base stations, or not and whether the radio channel used by any adjacent base station cannot be used by that base station due to interference with the use of the adjacent base station or can be used by that base station due to negligible interference, and wherein the radio channel which is not used by any of the adjacent base stations and the radio channel which is used by any adjacent base station but can be used by that base station due to negligible interference are selected preferentially in that order to be used for communication with the radio transceiver.

9. A wireless communication method according to claim 7, wherein said judging step includes the substeps of:

sending a call acknowledge signal upon receiving the call from the radio transceiver to the adjacent base stations and receiving call acknowledge signals sent from any of the adjacent base stations; and

judging whether that base station should respond to the received call or not with reference to the call acknowledge signals received from the adjacent base stations.

10. A wireless communication method according to claim 7, further comprising the steps, carried out by each of the base stations, of:

sending, when signal strength in communication with the radio transceiver through the selected radio channel becomes lower, to at least one of the adjacent base stations and hand-off request signal including an identifier number of the radio transceiver, said signal strength and a number of the radio channel as used;

monitoring, when receiving such a hand-off request signal from any of the adjacent base stations, said received hand-off request signal and sending to the adjacent base station from which said hand-off request signal is received a hand-off response including data indicative of signal strength of the monitored hand-off request signal; and

selecting, when receiving such hand-off response signals from more than one of the adjacent base stations, one of the more than one adjacent base stations to which the communication with the radio transceiver is to be transferred by comparison between said data included in said received hand-off response signals according to a predetermined rule, and sending to said selected one adjacent base station a hand-off control signal for requesting succeeding the communication with the radio transceiver.

11. A wireless communication method according to claim 10, further comprising the steps, carried out by each of the base stations, of:

sending, when receiving the hand-off request signal from any of the adjacent base stations and that base station is impossible to succeed the communication with the radio transceiver, a signal rejecting the hand-off of communication in place of said hand-off response signal.

12. A wireless communication method according to claim 10, further comprising the steps, carried out by each of the base stations, of:

continuing the communication with the radio transceiver when that base station receives no hand-off response signal from any of the adjacent base stations after sending the hand-off request signal for a predetermined time interval and then again sending the hand-off request signal to the adjacent base stations.