Spread spectrum wireless PBX

• US 4,672,658 A
• Filed: 10/23/1986
• Issued: 06/09/1987
• Est. Priority Date: 10/16/1985
• Status: Expired due to Term

• Current Assignee: Avaya Technology Corporation Miami Lakes FLA US
• Original Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Inventors: Kavehrad, Mohsen, McLane, Peter J.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/921,837
• Time in Patent Office: 229 Days
• Field of Search: 370/18, 370/19, 375/1, 375/7, 379/58, 379/60, 379/61, 379/63, 455/38
• US Class Current: 455/555
• CPC Class Codes: H04B 1/7093 Matched filter type
• CPC Class Codes: H04Q 11/00 Selecting arrangements for multiplex systems multiplex systems H04J
• CPC Class Codes: H04W 84/16 WPBX [Wireless Private Branch Exchange]

Abstract

The present invention relates to a wireless PBX network wherein direct sequence spread spectrum multiple access is used for voice and data communications to support a plurality of local-local and local-external calls. The present wireless PBX arrangement comprises a plurality of local user transceivers using a first separate unique chip sequence patterns for information communication and a second common chip sequence pattern for call-set up; and a central PBX comprising (a) a plurality of PBX transceivers, each of which uses a separate first chip sequence pattern which is matched to a corresponding local user transceiver; (b) a switching means for interconnecting local users to each other or to an external network via the associated PBX transceivers; and (c) a call set-up receiver responsive solely to initial call set-up information sent by any user using the second common chip sequence pattern. Optional selection diversity or equal gain combining diversity and/or error correction encoding may also be included in the transceivers.

Claims

1. A wireless local communication system comprising:

a plurality of separate local user transceivers, each local user transceiver comprising a transmitter and a receiver for respectively transmitting and receiving uniquely encoded direct sequence spread spectrum radio signals; and

a central Private Branch Exchange (PBX) comprising

a plurality of PBX transceivers, each PBX transceiver (a) being matched to a separate one of the plurality of local user transceivers to provide a separate matched pair of a local user/PBX transceiver and (b) including a separate transmitter and receiver, each transceiver of a matched pair of transceivers solely transmitting to and receiving from its matched transceiver direct sequence spread spectrum radio signals which are encoded in a manner unique to said matched pair of transceivers while substantially rejecting transmissions from any non-matched transceiver, and

a switching means for interconnecting any one of the plurality of PBX transceivers to any other one of the plurality of PBX transceivers and/or to an external communication network, said switching means being capable of supporting a plurality of simultaneous PBX transceiver-PBX transceiver and PBX transceiver-external network interconnections.

2. A wireless local communication system according to claim 1 wherein

the transmitters of each separate matched pair of a local user transceiver and a PBX transceiver comprise means for encoding an input digital bit stream into a unique direct sequence spread spectrum signal using a unique spread spectrum chip sequence for transmission to the receiver of the other transceiver of the matched pair of transceivers, and

the receivers of each separate matched pair of a separate local user transceiver and a separate PBX transceiver comprise means for decoding a direct sequence spread spectrum signal received from the other transceiver of the matched pair of transceivers into a recovered digital bit stream using said unique spread spectrum chip sequence used by the transmitter of the matched transceiver.

3. A wireless local communication system according to claim 2 wherein the transmitters in the plurality of local user transceiver further comprise

means responsive to call set-up control information including an origination and destination address received at the onset of a call from an associated end user for transmitting said call set-up control information to the central PBX in a direct sequence spread spectrum signal using a second unique spread spectrum chip sequence which is common to all said local user transmitters.

4. A wireless local communication system according to claim 3, wherein said central PBX further comprises

a call set-up receiver which is solely responsive to call set-up control information, including origination and destination addresses, received in the direct sequence spread spectrum signal encoded with the second spread spectrum chip sequence at the onset of a call from any one of said local user transmitters for generating appropriate control signals to the switching means.

5. A wireless local communication system according to claim 4, wherein the central PBX further comprises:

control means responsive to control signals indicating origination and destination addresses from either said call set-up receiver or the external communications network for (a) determining whether an open link exists through the switching means to interconnect the indicated origination and destination addresses, and (b) upon finding an available open link, closing said open link to connect the origination and destination users.

6. A wireless local communications system according to claims 2 or 4, wherein each of the receivers comprises:

a surface acoustic wave (SAW) matched filter correlator, responsive to a direct sequence spread spectrum signal received via multiple paths, for providing as an output signal only the received signals encoded with a predetermined spread spectrum chip sequence associated with said receiver and substantially rejecting all other direct sequence spread spectrum signals; and

an integration and latching means responsive to both the demodulated signal output of said SAW matched filter correlator and to a clock pulse generated from output of said SAW matched filter correlator, which integrates said demodulated signal output of said SAW matched filter over the period of each clock pulse, for gating out a single signal pulse per clock period.

7. A wireless local communication system according to claim 2 or 4, wherein each of the receivers comprises;

a receiver subsection for receiving direct sequence spread spectrum signals which propagate via multiple paths between transceivers of the system, the receiver subsection including;

a surface acoustic wave (SAW) matched filter correlator, responsive to a direct sequence spread spectrum signal received via multiple paths, for providing as an output signal only the received signals encoded with a predetermined spread spectrum chip sequence associated with said receiver and substantially rejecting all other direct sequence spread spectrum signals; and

path select means responsive to an output signal from said SAW correlator for providing as an output signal only the strongest signal received from one of the multiple paths and suppressing weaker signals received in the other multiple paths.

8. A wireless local communication system according to claim 7 wherein each of the receivers further comprises:

a plurality of said receiver subsections disposed in a parallel relationship to each other for providing diversity reception of the multiple path direct sequence spread spectrum signals; and

means responsive to the output signals from the path select means of the plurality of receiver subsections for selecting the strongest of said output signals.

9. A wireless local communication system according to claim 2, wherein each local user transmitter and PBX transmitter comprises:

An error correction encoding means responsive to an incoming information bit stream to be transmitted for encoding said incoming information bit stream with a predetermined error correction code.

10. A wireless local communication system according to claim 9 wherein each of the local user receivers and PBX receivers comprises:

an error correction decoder responsive to an information bit stream from the receiver decoding means for decoding the information bit stream with a predetermined error correction code to detect and correct errors therein.

11. A Central Private Branch Exchange (PBX) for use in a wireless local communication system comprising:

a plurality of PBX transceivers, each PBX transceivers including a seperate transmitter and receiver and receiver which are each arranged to transmit to, and receive from, a separate matched remote local user transceiver direct-sequence spread-spectrum radio, signals which are encoded in a manner unique to a matched pair of local user/PBX transceivers, while substanially rejecting transmissions from any other non-matched remote local user transceiver, and

a switching means for interconnecting any one of the plurality of PBX transceivers to any other one of the plurality of PBX transceivers and/or to an external communications network, said switching means being capable of supporting a plurality of simultaneous PBX transceiver-PBX transceiver and PBX transceiver-external network connections.

12. A Central PBX according to claim 11 wherein

the transmitter of each PBX transceiver comprises means for encoding an input digital bit stream into a unique direct sequence spread apectrum signal using a unique spread spectrum chip sequence for subsequent transmission to a receiver of a remote matched local user transceiver;

and

the receiver of each PBX transceiver comprises means for decoding a direct sequence spread spectrum signal received from a remote matched local user transceiver into a removed digital bit stream using a unique spread spectrum chip sequence used by a transmitter of the remote matched local user transceiver.

13. A Central PBX according to claim 11 wherein the Central PBX further comprises:

a call set-up receiver which is solely responsive to call set-up control information, including origination and desination addresses, received in a direct sequence spread spectrum signal encoded with a second spread-spectrum chip sequence at the onset of a call from any one of a plurality of remote local user transmitters for generating appropiate control signals to the switching means.

14. A Central PBX according to claim 13 wherein the Central PBX further comprises:

control means responsive to control signals indicating origination and destination addresses from either of the call set-up receiver or the external communications network for (a) determining whether an open link exists through the switching means to interconnect the indicated origination and destination addresses, and (b) upon finding available open link, closing the open link to connect the origination and destination users.

15. A Central PBX according to claims 12 or 13 wherein each receiver comprises

a surface acoustic wave (SAW) matched filter correlator, responsive to a direct sequence spread-spectrum signal received via multiple paths from a remote matched local user transceiver, for providing as an output signal only the received signals encoded with a predetermined spread-spectrum chip sequence associated with the receiver and substanially rejecting all other direct-sequence spread-spectrum signals and

an integration and latching means, responsive to bothe the demodulated signal output from the SAW matched filter correlator and a clock pulse generated from the ouptut of the SAW matched filter correlator, for integrating the demodulated signal output of the SAW matched filter correlator over the period of each clock pulse and gating out a single signal pulse per clock period.

16. A Central PBX according to claim 12 or 13 wherein each receiver of the Central PBX comprises:

a receiver subsection for receiving direct-sequence spread spectrum signals which propagate via multiple paths between remote local user transceivers and the Central PBX, the receiver subsection including;

a surface acoustic wave (SAW) matched filter correlator, responsive to a direct-sequence spread-spectrum signal received via multiple paths, for providing as an output signal only the received signals encoded with a predetermined spread-spectrum chip sequence associated with the receiver and substanially rejecting all other direct-sequence spread-spectrum signals; and

path selecting means responsive to an output signal from the SAW matched filter correlator for providing as an outptut signal only the strongest signal received from one of the multiple paths and suppressing weaker signals received in the other multiple paths.

17. A Central PBX according to claim 12 wherein each PBX receiver further comprises:

an error correction decoder responsive to an information bit stream from the receiver decoding means for decoding the information bit stream with a predetermined error correction code to direct and correct errors therein.

18. A transceiver for use in a wireless communication system, the transceiver comprising:

a transmitter including means for encoding an input digital bit stream into a unique direct-sequence spread-spectrum radio signal using a unique spread-spectrum chip sequence for subsequent transmission of the unique direct-sequence spread-spectrum radio signal to a receiver of another remote transceiver, and means responsive to call set-up control information including an origination and destination address for transmitting the call set-up control information in a direct-sequence spread-spectrum signal using a second unique spread-spectrum chip sequence; and

a receiver for receiving uniquely encoded direct-sequence spread-spectrum raiio signals from ome or more remote transceivers, the receiver including means for decoding a direct-sequence spread-spectrum signal received from one of said one or more transceivers into a recovered digital bit stream using the unique spread-spectrum chip sequence used by the transmitter of the one of said one or more transceivers while substanially rejecting transmissions from any other transceiver.

19. A transceiver according to claim 18 wherein the receiver further comprises:

a surface acoustic wave (SAW) matched filter correlator, responsive to a direct-sequence spread-spectrum signal received via multiple paths for providing as an output signal only the received signals encoded with a predetermined spread-spectrum chip sequence associated with the receiver and substanially rejecting all other direct-sequence spread-spectrum signals; and

an integration and latching means responsive to both the demodulated signal output of the SAW matched filter correlator and a clock pulse generated from the output of the SAW matched filter correlator, for integrating the demodulated signal output of the SAW matched filter correlator over the period of each clock pulse and gating out a single pulse per clock period.

20. A transceiver according to claim 18 wherein the receiver further comprises:

a receiver subsection for receiving direct-sequence spread-spectrum signals which propagate via multiple paths, the receiver subsection including;

a surface acoustic wave SAW matched filter correlator, responsive to a direct-sequence spread-spectrum signal received via multiple paths, for providing as an output signal only the received signals encoded with a predetermined spread-spectrum chip sequence associated with the receiver and substanially rejecting all other direct-sequence spread-spectrum signals; and

path select means responsive to an output signal from the SAW correlator for providing as an output signal only the strongest signal received form one of the multiple paths and supressing weaker signals received in the other multiple paths.

21. A transceiver according to claim 19 wherein the receiver further comprises:

a plurality of the receiver subsections disposed in a parallel relationship to each other for providing diversity reception on the multiple-path direct-sequence spread-spectrum signals; and

PG means responsive to the output signals from the path select means of the plurality of receiver subsections for selecting the strongest of the output signals.

22. A transceiver according to claim 18 wherein the transmitter further comprises:

an error correction encoding means to an incoming information bit stream to be transmitted for encoding the incoming information bit stream with a predetermined error correction code.

23. A transceiver according to claim 22 wherein the receiver further comprises:

an error correction decoder responsive to an information bit stream from the receiver decoding means for decoding the information bit stream with a predetermined error correction code to detect and correct errors therein.