CA2583679A1

CA2583679A1 - Synchronous spread-spectrum communications system and method

Info

Publication number: CA2583679A1
Application number: CA002583679A
Authority: CA
Inventors: Donald L. Schilling
Original assignee: Interdigital Technology Corporation; Donald L. Schilling; Scs Mobilecom, Inc.
Current assignee: InterDigital Technology Corp
Priority date: 1990-12-14
Filing date: 1991-12-10
Publication date: 1992-06-15
Anticipated expiration: 2011-12-10
Also published as: CA2583679C

Abstract

A spread spectrum communications system for use over a communications channel, including a transmitter-generic-chip-code generator, a transmitter-message-chip-code generator, an EXCLUSIVE-OR gate, a combiner, a transmitter, a receiver-generic-chip-code generator, a receiver--generic mixer, a generic-bandpass filter, a receiver-message-chip-code generator, a receiver-message mixer, a message-bandpass filter, and a synchronous detector. The transmitter-generic-chip-code generator generates a generic-chip-code signal and the transmitter-message-chip-code generator generates a message-chip-code signal. The EXCLUSIVE-OR gate spread-spectrum processes message data with the message-chip-code signal to generate a spread-spectrum signal. The combiner combines the generic--chip-code signal with the spread-spectrum-processed signal. The transmitter transmits the combined generic-chip-code signal and spread-spectrum signal, on a carrier signal over the communications channel as a spread-spectrum--communications signal. The receiver-generic-chip-code generator generates a replica of the generic-chip-code signal. The generic mixer recovers the carrier signal from the spread-spectrum-communications signal. The receiver-message-chip-code generator generates a replica of the message--chip-code signal. The receiver-message mixer despreads the spread--spectrum-communications signal as a modulated-data signal. The tracking and acquisition circuit uses the recovered carrier signal for synchronizing the replicas of the generic-chip-code signal to the recovered carrier signal. The synchronous detector synchronously demodulates the modulated-data signal as received data.

Claims

1. A method for transmitting message data from a code division multiple access transmitter, the method comprising:
providing a bit sequence;
combining each bit of the bit sequence with a plurality of chips, producing a first signal;
providing message data;
combining each bit of the message data with a plurality of chips, producing a second signal;
combining the first signal with the second signal to produce a spread spectrum signal; whereby the first signal facilitates a receiver to synchronize to the second signal.

2. The method of claim 1 wherein the first bit sequence is a code word.

3. The method of claim 1 comprising providing second message data; combining each bit of the second message data with a plurality of chips, producing a third signal; combining the first, second and third signals to produce the spread spectrum signal; whereby the first signal facilitates a receiver to synchronize to the second and third signals.

4. The method of claim 1 wherein the plurality of chips of the first signal are different than the plurality of chips of the second signal.

5. A transmitter for transmitting message data in a code division multiple access format, the base station comprising:
a code generator that combines each bit of a bit sequence with a plurality of chips, producing a first signal;
a mixing device that combines each bit of message data with a plurality of chips, producing a second signal;
a combiner that combines the first signal with the second signal to produce a spread spectrum signal; whereby the first signal facilitates a receiver to synchronize to the second signal.

6. The transmitter of claim 5 wherein the first bit sequence is a code word.

7. The transmitted of claim 5 comprising a second mixing device that combines each bit of second message data with a plurality of chips, producing a third signal and wherein the combiner combines the first signal with the second signal to produce a spread spectrum signal; whereby the first signal facilitates a receiver to synchronize to the second and third signal.

8. The transmitter of claim 5 wherein the plurality of chips of the first signal are different than the plurality of chips of the second signal.

9. A method for receiving message data from a code division multiple access transmitter, the method comprising:
receiving a spread spectrum signal;
detecting a first signal within the spread spectrum signal, the first signal having each bit of a bit sequence combined with a plurality of chips;
recovering message data from a second signal within the spread spectrum signal, the second signal having each bit of the message data combined with a plurality of chips; wherein the recovering of the message data is synchronized to the detected first signal.

10. The method of claim 9 wherein the first bit sequence is a code word.

11. The method of claim 9 comprising recovering second message data from a third signal within the spread spectrum signal, the third signal having each bit of the second message data combined with a plurality of chips, wherein the recovering of the second message data is synchronized to the detected first signal.

12. The method of claim 9 wherein the plurality of chips of the first signal are different than the plurality of chips of the second signal.

13. A receiver for receiving message data in a code division multiple access format, the receiver comprising:
an input that receives a spread spectrum signal;
a detector that detects a first signal within the spread spectrum signal, the first signal having each bit of a bit sequence combined with a plurality of chips;
a mixing device that recovers message data from a second signal within the spread spectrum signal, the second signal having each bit of the message data combined with a plurality of chips; wherein the recovering of the message data is synchronized to the detected first signal.

14. The receiver of claim 13 wherein the first bit sequence is a code word.

15. The method of claim 13 comprising a second mixing device that recovers second message data from a third signal within the spread spectrum signal, the third signal having each bit of the message data combined with a plurality of chips; wherein the recovering of the second message data is synchronized to the detected first signal.

16. The method of claim 13 wherein the plurality of chips of the first signal are different than the plurality of chips of the second signal.