Multi-access hybrid OFDM-CDMA system

• US 8,472,306 B2
• Filed: 06/10/2010
• Issued: 06/25/2013
• Est. Priority Date: 10/18/2001
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Walton, J. Rodney, Ketchum, John W., Howard, Steven J., Wallace, Mark
• Primary Examiner(s): NGUYEN, STEVEN H D
• Application Number:
  US12/813,461
• Publication Number:
  US 20100246642A1
• Time in Patent Office: 1,111 Days
• Field of Search: 370208-210, 370335-342
• US Class Current: 370/208
• CPC Class Codes: H04B 1/692 Hybrid techniques using combinations of two or more spread spectrum techniques
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04L 27/2607 Cyclic extensions
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 5/0021 in which codes are applied as a frequency-domain sequences, e.g. MC-CDMA
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/026 using code division
• CPC Class Codes: H04W 52/12 Outer and inner loops
• CPC Class Codes: H04W 52/286 during data packet transmission, e.g. high speed packet access [HSPA]

Abstract

In one aspect of a multiple-access OFDM-CDMA system, the data spreading is performed in the frequency domain by spreading each data stream with a respective spreading code selected from a set of available spreading codes. To support multiple access, system resources may be allocated and de-allocated to users (e.g., spreading codes may be assigned to users as needed, and transmit power may be allocated to users). Variable rate data for each user may be supported via a combination of spreading adjustment and transmit power scaling. Interference control techniques are also provided to improve system performance via power control of the downlink and/or uplink transmissions to achieve the desired level of performance while minimizing interference. A pilot may be transmitted by each transmitter unit to assist the receiver units perform acquisition, timing synchronization, carrier recovery, handoff, channel estimation, coherent data demodulation, and so on.

Claims

1. An apparatus for processing data for transmission over a wireless communication channel in a multiple-access OFDM-CDMA system, comprising:

means for coding a data stream in accordance with a particular coding scheme to provide a stream of data symbols;

means for spreading the data symbol stream in a frequency domain with one or more spreading codes to provide spread data, wherein the one or more spreading codes are selected from a set of available spreading codes and assigned to the data stream;

means for transforming the spread data in accordance with a particular transformation to provide a stream of OFDM symbols;

means for scaling the stream of OFDM symbols in accordance with a particular gain selected for the data stream, wherein the particular gain is based upon an estimated signal quality;

means for covering the scaled OFDM symbols with a cover code; and

means for transmitting the covered OFDM symbols over the communication channel.

2. The apparatus of claim 1, further comprising:

means for appending a cyclic prefix to each OFDM symbol to provide a corresponding transmission symbol, wherein transmission symbols are scaled and transmitted over the communication channel.

3. The apparatus of claim 1, further comprising:

means for adjusting the spreading based on a data rate of the data stream.

4. The apparatus of claim 1, further comprising:

means for adjusting the gain to adjust transmit power for the data stream.

5. The apparatus of claim 1, wherein the scaled OFDM symbols are transmitted on a downlink from a base station to a terminal.

6. The apparatus of claim 1, wherein the scaled OFDM symbols are transmitted on an uplink from a terminal to a base station.

7. An apparatus for processing data for transmission over a wireless communication channel in a multiple-access OFDM-CDMA system, comprising:

means for coding a data stream in accordance with a particular coding scheme to provide a stream of data symbols;

means for spreading the data symbol stream in a frequency domain with one or more spreading codes to provide spread data, wherein the one or more spreading codes are selected from a set of available spreading codes and assigned to the data stream;

means for transforming the spread data in accordance with an inverse Fourier transform to provide a stream of OFDM symbols;

means for appending a cyclic prefix to each OFDM symbol to provide a corresponding transmission symbol;

means for scaling each transmission symbol in accordance with a particular gain selected for the data stream, wherein the particular gain is based upon an estimated signal quality responsive to a power control command of a particular multiple access power control scheme;

means for covering scaled transmission symbols with a cover code; and

means for transmitting the covered transmission symbols over the communication channel.

8. An apparatus for processing data for transmission over a wireless communication channel, comprising:

means for coding a data stream to provide a stream of data symbols;

means for applying one or more spreading codes to the stream of data symbols in a frequency domain to provide spread data;

means for generating a stream of OFDM symbols from the spread data;

means for applying a gain to the stream of OFDM symbols based upon information regarding a communication channel over which at least some of the stream of OFDM symbols are to be transmitted, wherein the information regarding a communication channel comprises an estimated signal quality of symbols transmitted over the communication channel; and

means for adjusting the spreading based on a data rate of the stream of data symbols.

9. The apparatus of claim 8, wherein the information regarding a communication channel comprises feedback from a receiver of symbols over the communication channel.

10. The apparatus of claim 8, wherein the means for adjusting the spreading includes means for assigning a plurality of spreading codes to the stream of data symbols.

11. The apparatus of claim 8, wherein the means for applying one or more spreading codes is effectively not performed when the data rate of the data stream reaches a particular threshold data rate.

12. A computer-program storage apparatus for processing data for transmission over a wireless communication channel in a multiple-access OFDM-CDMA system comprising a memory having one or more software modules stored thereon, the one or more software modules being executable by one or more processors and the one or more software modules comprising:

code for coding a data stream in accordance with a particular coding scheme to provide a stream of data symbols;

code for spreading the data symbol stream in a frequency domain with one or more spreading codes to provide spread data, wherein the one or more spreading codes are selected from a set of available spreading codes and assigned to the data stream;

code for transforming the spread data in accordance with a particular transformation to provide a stream of OFDM symbols;

code for scaling the stream of OFDM symbols in accordance with a particular gain selected for the data stream, wherein the particular gain is based upon an estimated signal quality;

code for covering the scaled OFDM symbols with a cover code; and

code for transmitting the covered OFDM symbols over the communication channel.

13. The apparatus of claim 12, further comprising:

code for appending a cyclic prefix to each OFDM symbol to provide a corresponding transmission symbol, wherein transmission symbols are scaled and transmitted over the communication channel.

14. The apparatus of claim 12, further comprising:

code for adjusting the spreading based on a data rate of the data stream.

15. The apparatus of claim 12, further comprising:

code for adjusting the gain to adjust transmit power for the data stream.

16. The apparatus of claim 12, wherein the scaled OFDM symbols are transmitted on a downlink from a base station to a terminal.

17. The apparatus of claim 12, wherein the scaled OFDM symbols are transmitted on an uplink from a terminal to a base station.

18. A computer-program storage apparatus for processing data for transmission over a wireless communication channel in a multiple-access OFDM-CDMA system comprising a memory having one or more software modules stored thereon, the one or more software modules being executable by one or more processors and the one or more software modules comprising:

code for coding a data stream in accordance with a particular coding scheme to provide a stream of data symbols;

code for spreading the data symbol stream in a frequency domain with one or more spreading codes to provide spread data, wherein the one or more spreading codes are selected from a set of available spreading codes and assigned to the data stream;

code for transforming the spread data in accordance with an inverse Fourier transform to provide a stream of OFDM symbols;

code for appending a cyclic prefix to each OFDM symbol to provide a corresponding transmission symbol;

code for scaling each transmission symbol in accordance with a particular gain selected for the data stream, wherein the particular gain is based upon an estimated signal quality responsive to a power control command of a particular multiple access power control scheme;

code for covering scaled transmission symbols with a cover code; and

code for transmitting the covered transmission symbols over the communication channel.

19. A computer-program storage apparatus for processing data for transmission over a wireless communication channel comprising a memory having one or more software modules stored thereon, the one or more software modules being executable by one or more processors and the one or more software modules comprising:

code for coding a data stream to provide a stream of data symbols;

code for applying one or more spreading codes to the stream of data symbols in a frequency domain to provide spread data;

code for generating a stream of OFDM symbols from the spread data;

code for applying a gain to the stream of OFDM symbols based upon information regarding a communication channel over which at least some of the stream of OFDM symbols are to be transmitted, wherein the information regarding a communication channel comprises an estimated signal quality of symbols transmitted over the communication channel; and

code for adjusting the spreading based on a data rate of the stream of data symbols.

20. The apparatus of claim 19, wherein the information regarding a communication channel comprises feedback from a receiver of symbols over the communication channel.

21. The apparatus of claim 19, wherein the code for adjusting the spreading includes code for assigning a plurality of spreading codes to the stream of data symbols.

22. The apparatus of claim 19, wherein the code for applying one or more spreading codes is effectively not performed when the data rate of the data stream reaches a particular threshold data rate.