Method and apparatus for providing high data rate traffic channels in a spread spectrum communication system

• US 5,204,876 A
• Filed: 03/13/1991
• Issued: 04/20/1993
• Est. Priority Date: 03/13/1991
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Eyuboglu, Vedat, Bruckert, Eugene J., Falconer, David D.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): CAIN, DAVID C
• Application Number:
  US07/669,127
• Time in Patent Office: 769 Days
• Field of Search: 375/1
• US Class Current: 375/130
• CPC Class Codes: H03M 13/2703 the interleaver involving at least two directions
• CPC Class Codes: H03M 13/2732 Convolutional interleaver; Interleavers using shift-registers or delay lines like, e.g. Ramsey type interleaver
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04J 13/004 Orthogonal
• CPC Class Codes: H04J 13/18 Allocation of orthogonal codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence

Abstract

A method and apparatus is provided for transmitting spread spectrum signals. The transmitter receives data bits at a particular rate. Subsequently, the transmitter encodes the received data bits at a predetermined encoding rate into data symbols. Subsequently, the transmitter derives predetermined length orthogonal codes from the data symbols. The transmitter accommodates variable received data bit rates by setting the predetermined encoding rate and the predetermined orthogonal code length in response to the received data bit rate. Subsequently, the transmitter spreads the derived orthogonal codes with a user PN spreading code.

An alternative method and apparatus is provided for transmitting spread spectrum signals. The transmitter receives data bits at a particular rate. Subsequently, the transmitter encodes the received data bits at a predetermined encoding rate into data symbols. Subsequently, the transmitter determines a particular channel to transmit the data symbols by spreading the data symbols with a predetermined length orthogonal code. The transmitter accommodates variable received data bit rates by setting the predetermined encoding rate and the predetermined orthogonal code length in response to the received data bit rate.

Claims

1. A spread spectrum channel apparatus which accommodates variable received data bit rates, comprising:

(a) forward error correction encoder

means for receiving data bits at a particular bit rate and encoding the received data bits at a predetermined encoding rate into data symbols, the predetermined encoding rate being set in response to the received data bit rate; and

(b) modulator means, operatively coupled to the forward error correction encoder means, for deriving predetermined length orthogonal codes from the data symbols, the predetermined length of the orthogonal codes being set in response to the received data bit rate.

2. The spread spectrum channel apparatus of claim 1 wherein the forward error correction encoder means comprises means for setting the predetermined encoding rate through implementation of a puncture algorithm.

3. The spread spectrum channel apparatus of claim 1 wherein the forward error correction encoder means comprises a symbol interleaver means for scrambling the data symbols prior to the modulator means deriving orthogonal codes from the data symbols.

4. The spread spectrum channel apparatus of claim 1 further comprising a transmitting means, operatively coupled to the modulator means, for transmitting the derived orthogonal codes over a communication channel, the transmitting means comprises spreading means for preparing the derived orthogonal codes for subsequent transmission by spreading the derived orthogonal codes with a spreading code.

5. The spread spectrum channel apparatus of claim 4 further comprising:

(a) despreading means for sampling the transmitted spread orthogonal codes received from over the communication channel into data samples by despreading the received orthogonal codes with a spreading code; and

(b) decoding means, operatively coupled to the despreading means, for generating an estimated data bit by deriving the estimated data bit from the data samples.

6. A spread spectrum channel apparatus which accommodates variable received data bit rates, comprising:

(a) despreading means for sampling a signal received from over the communication channel into data samples by despreading the received signal with a spreading code, the received signal comprising spread orthogonal codes wherein the spread orthogonal codes were formed from data bits received at a particular bit rate and encoded at a predetermined encoding rate into data symbols, predetermined length orthogonal codes were derived from the data symbols, and subsequently the derived orthogonal codes were prepared for subsequent transmission by being spread with a spreading code, the predetermined encoding rate and the predetermined length of the orthogonal codes having been set in response to the received data bit rate; and

(b) decoding means, operatively coupled to the despreading means, for generating an estimated data bit by deriving the estimated data bit from the data samples.

7. A spread spectrum channel apparatus which accommodates variable received data bit rates, comprising:

(a) forward error correction encoder

means for receiving data bits at a particular bit rate and encoding the received data bits at a predetermined encoding rate into data symbols, the predetermined encoding rate being set in response to the received data bit rate; and

(b) code division channel means, operatively coupled to the forward error correction encoder means, for determining a particular channel to transmit the data symbols by spreading the data symbols with a predetermined length orthogonal code, the predetermined length of the orthogonal code being set in response to the received data bit rate.

8. The spread spectrum channel apparatus of claim 7 wherein the forward error correction encoder means comprises means for setting the predetermined encoding rate through implementation of a puncture algorithm.

9. The spread spectrum channel apparatus of claim 7 wherein the forward error correction encoder means comprises scrambling means for scrambling the data symbols with a spreading code prior to the code division channel means determining a particular channel to transmit the data symbols by spreading the data symbols with a predetermined length orthogonal code.

10. The spread spectrum channel apparatus of claim 7 wherein the forward error correction encoder means comprises a symbol interleaver means for scrambling the data symbols prior to the code dividion channel means determining a particular channel to transmit the data symbols by spreading the data symbols with a predetermined length orthogonal code.

11. The spread spectrum channel apparatus of claim 7 further comprising a transmitting means, operatively coupled to the code division channel means, for transmitting the orthogonal coded spread data symbols over a communication channel, the transmitting means comprises spreading means for preparing the orthogonal coded data symbols for subsequent transmission by spreading the orthogonal coded data symbols with a spreading code.

12. The spread spectrum channel apparatus of claim 11 further comprising:

(a) despreading means for sampling the transmitted spread orthogonal codes received from over the communication channel into data samples by despreading the received orthogonal codes with a spreading code; and

(b) decoding means, operatively coupled to the despreading means, for generating an estimated data bit by deriving the estimated data bit from the data samples.

14. The spread spectrum channel apparatus of claim 7 wherein the code division channel means comprises means for limiting the number of orthogonal codes used when a less than maxiumum length orthogonal code is used such that orthogonality of the maximum length orthogonal codes is maintained with respect to the less than maximum length orthogonal code.

13. A spread spectrum channel apparatus which accommodates variable received data bit rates, comprising:

(a) despreading means for sampling a signal received from over the communication channel into data samples by despreading the received signal with a spreading code, the received signal comprising spread orthogonal codes wherein the spread orthogonal codes were formed from data bits received at a particular bit rate and encoded at a predetermined encoding rate into data symbols, predetermined length orthogonal codes spread the data symbols, and subsequently the orthogonal code spread data symbols were prepared for subsequent transmission by being spread with a spreading code, the predetermined encoding rate and the predetermined length of the orthogonal codes having been set in response to the received data bit rate; and

(b) decoding means, operatively coupled to the despreading means, for generating an estimated data bit by deriving the estimated data bit from the data samples.

15. A method of communicating a spread spectrum signal while accommodating variable traffic data bit rates, comprising:

(a) determining the particular bit rate at which received traffic data bits were provided to a spread spectrum channel apparatus;

(b) setting a predetermined encoding rate and a predetermined length for an orthogonal code in response to the determined particular bit rate;

(c) encoding received data bits at the predetermined encoding rate into data symbols; and

(d) deriving orthogonal codes of the predetermined length from the data symbols.

16. The method of claim 15 wherein the step of setting the predetermined encoding rate comprises implementation of a puncture algorithm.

17. The method of claim 15 further comprising the step of interleaving the data symbols prior to the step of deriving predetermined length orthogonal codes from the data symbols.

18. The method of claim 15 further comprising the step of transmitting the derived orthogonal codes over a communication channel, the transmitting step comprising preparing the derived orthogonal codes for subsequent transmission by spreading the derived orthogonal codes with a spreading code.

19. The method of claim 18 further comprising the steps of

(a) sampling the transmitted spread orthogonal codes received from over the communication channel into data samples by despreading the received orthogonal codes with a spreading code;

and

(b) generating an estimated data bit by deriving the estimated data bit from the data samples.

20. A method of communicating a spread spectrum signal while accommodating variable traffic data bit rates, comprising:

(a) sampling a signal received from over the communication channel into data samples by despreading the received signal with a spreading code, the received signal comprising spread orthogonal codes wherein the spread orthogonal codes were formed from data bits received at a particular bit rate and encoded at a predetermined encoding rate into data symbols, predetermined length orthogonal codes were derived from the data symbols, and subsequently the derived orthogonal codes were prepared for subsequent transmission by being spread with a spreading code, the predetermined encoding rate and the predetermined length of the orthogonal codes having been set in response to the received data bit rate; and

(b) generating an estimated data bit by deriving the estimated data bit from the data samples.

21. A method of communicating a spread spectrum signal while accommodating variable traffic data bit rates, comprising:

(a) determining the particular bit rate at which received traffic data bits were provided to a spread spectrum channel apparatus;

(b) setting a predetermined encoding rate and a predetermined length for an orthogonal code in response to the determined particular bit rate;

(c) encoding received data bits at the predetermined encoding rate into data symbols; and

(d) determining a particular channel to transmit the data symbols by spreading the data symbols with a predetermined length orthogonal code.

22. The method of claim 21 wherein the step of setting the predetermined encoding rate comprises implementation of a puncture algorithm.

23. The method of claim 21 further comprising the step of scrambling the data symbols with a spreading code prior to the step of determining a particular channel to transmit the data symbols.

24. The method of claim 21 further comprising the step of interleaving the data symbols prior to the step of determining a particular channel to transmit the data symbols.

25. The method of claim 21 further comprising the step of transmitting the orthogonal coded spread data symbols over a communication channel, the step of transmitting comprising preparing the orthogonal coded data symbols for subsequent transmission by spreading the orthogonal coded data symbols with a spreading code.

26. The method of claim 25 further comprising the steps of;

(a) sampling the transmitted spread orthogonal codes received from over the communication channel into data samples by despreading the received orthogonal codes with a spreading code; and

(b) generating an estimated data bit by deriving the estimated data bit from the data samples.

28. The method of claim 21 further comprising the step of limiting the number of orthogonal codes used in the step of determining a particular channel to transmit the data symbols when a less than maximum length orthogonal code is used such that orthogonality of the maximum length orthogonal codes is maintained with respect to the less than maximum length orthogonal code.

27. A method of communicating a spread spectrum signal while accommodating variable traffic data bit rates, comprising:

(a) sampling a signal received from over the communication channel into data samples by despreading the received signal with a spreading code, the received signal comprising spread orthogonal codes wherein the spread orthogonal codes were formed from data bits received at a particular bit rate and encoded at a predetermined encoding rate into data symbols, predetermined length orthogonal codes spread the data symbols, and subsequently the orthogonal code spread data symbols were prepared for subsequent transmission by being spread with a spreading code, the predetermined encoding rate and the predetermined length of the orthogonal codes having been set in response to the received data bit rate; and

(b) generating an estimated data bit by deriving the estimated data bit from the data samples.