Method and apparatus for processing data for transmission in a multi-channel communication system using selective channel transmission

• US 20030043732A1
• Filed: 06/26/2001
• Published: 03/06/2003
• Est. Priority Date: 05/17/2001
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ketchum, John W., Walton, Jay R.
• Granted Patent: US 6,751,187 B2
• Time in Patent Office: Days
• US Class Current: 370/208
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 17/382 for resource allocation, admission control or handover
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/0019 in which mode-switching is based on a statistical approach
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0029 Reduction of the amount of signalling, e.g. retention of useful signalling or differential signalling power control H04W52/04
• CPC Class Codes: H04L 1/0068 by puncturing
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 2001/0096 Channel splitting in point-to-point links
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/021 Estimation of channel covariance
• CPC Class Codes: H04L 25/0244 with inversion
• CPC Class Codes: H04L 25/0248 Eigen-space methods
• CPC Class Codes: H04L 25/03057 with a recursive structure H04L25/03031 takes precedence
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0025 Spatial division following the spatial signature of the channel
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0046 Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0053 : Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/006 : Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0091 : Signaling for the administration of the divided path
• CPC Class Codes: H04W 52/24 : using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/26 : using transmission rate or quality of service QoS [Quality of Service]
• CPC Class Codes: H04W 52/346 : distributing total power among users or channels
• CPC Class Codes: H04W 52/42 : in systems with time, space, frequency or polarisation diversity
• CPC Class Codes: H04W 52/50 : at the moment of starting communication in a multiple access environment

Abstract

Techniques to select transmission channels for use for data transmission and to process and transmit data over the selected transmission channels. Transmission channels available for use are segregated into one or more groups, with each group including any number of channels. With selective channel transmission, only “good” channels in each group are selected (e.g., based on the channels'"'"' received SNRs and an SNR threshold), “bad” channels are not used, and the total available transmit power for the group is (e.g., uniformly) distributed across only the good channels. Each group may also be associated with a respective coding and modulation scheme, and data for each group may be coded and modulated based on the scheme selected for the group. Improved performance is achieved by using only good channels in each group and matching the data processing for the selected channels to the capacity achievable by the channels.

Claims

1. A method for processing data for transmission over multiple transmission channels in a multi-channel communication system, comprising:

estimating characteristics of a plurality of transmission channels available for data transmission;

segregating the plurality of transmission channels into one or more groups of transmission channels; and

for each group of transmission channels,

selecting one or more transmission channels for use for data transmission based on the estimated channel characteristics,

allocating total transmit power available for the group amongst the one or more selected transmission channels in accordance with a defined allocation scheme,

coding and modulating data for the one or more selected transmission channels, and

transmitting the coded and modulated data for each selected transmission channel based on the allocated transmit power.

2. The method of claim 1, wherein the total transmit power available for each group is allocated approximately equally amongst the one or more selected transmission channels in the group.

3. The method of claim 1, wherein the total transmit power available for each group is allocated non-uniformly amongst the one or more selected transmission channels in the group.

4. The method of claim 3, wherein greater amount of transmit power is allocated to transmission channels capable of achieving higher performance.

5. The method of claim 1, wherein the one or more transmission channels in each group are selected based in part on performance achievable with the total transmit power allocated in accordance with the defined allocation scheme.

6. The method of claim 1, further comprising:

interleaving the data for each group in accordance with an interleaving scheme.

7. The method of claim 6, wherein the data for each group is interleaved across all selected transmission channels in the group.

8. The method of claim 1, wherein the one or more transmission channels in each group are further selected based on a threshold.

9. The method of claim 8, wherein the threshold for each group is selected to provide high throughput for the selected transmission channels in the group.

10. The method of claim 8, wherein the threshold for each group is selected to provide a highest possible throughput for the transmission channels available in the group.

11. The method of claim 8, wherein the threshold for each group is a particular target received signal-to-noise-plus-interference ratio (SNR).

12. The method of claim 1, wherein each group is associated with a respective threshold used for selecting the one or more transmission channels.

13. The method of claim 1, wherein the data for the one or more selected transmission channels in each group is coded and modulated based on a common coding and modulation scheme.

14. The method of claim 1, wherein the data for each group is coded and modulated based on a respective coding and modulation scheme selected for the group.

15. The method of claim 14, wherein the coding and modulation scheme for each group is selected from among a plurality of possible coding and modulation schemes.

16. The method of claim 1, wherein the multi-channel communication system is an orthogonal frequency division modulation (OFDM) system, and wherein the plurality of transmission channels correspond to a plurality of frequency subchannels.

17. The method of claim 1, wherein the multi-channel communication system is a multiple-input multiple-output (MIMO) communication system, and wherein the plurality of transmission channels correspond to a plurality of spatial subchannels of a MIMO channel.

18. The method of claim 17, wherein the MIMO communication system utilizes OFDM, and wherein the plurality of transmission channels correspond to a plurality of spatial subchannels of a plurality of frequency subchannels.

19. The method of claim 18, wherein each group corresponds to a respective transmit antenna and includes a plurality of transmission channels corresponding to a plurality of frequency subchannels.

20. The method of claim 1, wherein the estimated channel characteristics are channel gains.

21. The method of claim 20, wherein, for each group, transmission channels having power gains greater than or equal to a particular power gain threshold are selected, and wherein the power gains are derived from the channel gains.

22. The method of claim 1, wherein the estimated channel characteristics are received signal-to-noise-plus-interference ratios (SNRs).

23. The method of claim 22, wherein, for each group, transmission channels having SNRs greater than or equal to a particular SNR threshold are selected.

24. A method for controlling data transmission in a multi-channel communication system, comprising:

receiving a plurality of transmissions via a plurality of transmission channels;

estimating characteristics of the plurality of transmission channels based on the received transmissions;

selecting one or more transmission channels for use for data transmission based on the estimated channel characteristics and a metric; and

sending channel state information (CSI) for the plurality of transmission channels, and wherein total transmit power available for the plurality of transmission channels is allocated amongst the one or more selected transmission channels in accordance with a defined allocation scheme, and wherein data is transmitted over each selected transmission channel based on the allocated transmit power.

25. The method of claim 24, wherein the defined allocation scheme uniformly distributes the total transmit power amongst the one or more selected transmission channels.

26. The method of claim 24, wherein the CSI identifies the one or more selected transmission channels.

27. The method of claim 26, wherein the CSI comprises a channel mask to identify the one or more selected transmission channels.

28. The method of claim 24, wherein the CSI identifies a particular coding and modulation scheme to be used for the one or more selected transmission channels.

29. The method of claim 24, wherein the CSI identifies a particular data rate to be used for the one or more selected transmission channels.

30. The method of claim 24, wherein the CSI comprises differential indicator identifying changes since previously sent CSI.

31. The method of claim 24, wherein the data transmitted over the one or more selected transmission channels is coded and modulated in accordance with a common coding and modulation scheme.

32. In a multi-channel communication system, a method for selecting transmission channels for use for data transmission, comprising:

defining a set of code rates, wherein each code rate is selectable for coding data prior to transmission;

defining a set of setpoints, wherein each setpoint corresponds to a respective code rate and is indicative of a target signal-to-noise-plus-interference ratio (SNR) required for a particular level of performance at the corresponding code rate;

for each code rate,

identifying one or more transmission channels for possible use for data transmission, wherein the one or more identified transmission channels achieve the setpoint corresponding to the code rate when total available transmit power is distributed amongst the one or more identified transmission channels in accordance with a defined allocation scheme, and

determining a performance metric for the code rate based on the one or more identified transmission channels and the allocated transmit power; and

selecting the identified transmission channels associated with the code rate having a highest performance metric for use for data transmission.

33. The method of claim 32, wherein the defined allocation scheme uniformly distributes the total available transmit power amongst the identified transmission channels.

34. The method of claim 32, wherein the performance metric for each code rate is an overall throughput achievable by the identified transmission channels.

35. A transmitter unit in a multi-channel communication system, comprising:

a controller operative to receive channel state information (CSI) for a plurality of transmission channels available for use for data transmission, segregate the available transmission channels into one or more groups, and select one or more available transmission channels in each group for use for data transmission based on the received CSI; and

a transmit data processor coupled to the controller and operative to receive, code, and modulate data for each group based on a particular coding and modulation scheme to provide modulation symbols, distribute total transmit power available for each group amongst the one or more selected transmission channels in the group in accordance with a defined allocation scheme, and transmit the modulation symbols for each selected transmission channel based on the allocated transmit power.

36. The transmitter of claim 35, wherein the defined allocation scheme uniformly distributes the total available transmit power for each group amongst the one or more selected transmission channels in the group.

37. The transmitter of claim 35, further comprising:

a transmit channel processor coupled to the transmit data processor and operative to receive and demultiplex the modulation symbols into one or more symbol streams, one symbol stream for each antenna used to transmit the modulation symbols.

38. The transmitter of claim 37, wherein the transmit channel processor is further operative to precondition the modulation symbols based on the received CSI.

39. A receiver unit in a multi-channel communication system, comprising:

a receive data processor operative to process a plurality of transmissions received via a plurality of transmission channels and to estimate characteristics of the plurality of transmission channels based on the processed transmissions;

a controller coupled to the receive data processor and operative to select, based on the estimated channel characteristics and a metric, one or more transmission channels for use for data transmission; and

a transmit data processor coupled to the controller and operative to transmit channel state information (CSI) for the plurality of transmission channels, and

wherein total transmit power available for the plurality of transmission channels is allocated amongst the one or more selected transmission channels in accordance with a defined allocation scheme, and wherein data is transmitted to the receiver unit over each selected transmission channel based on the allocated transmit power.

40. The receiver of claim 39, wherein the defined allocation scheme uniformly distributes the total available transmit power amongst the one or more selected transmission channels.