Bit distributor for multicarrier communication systems employing adaptive bit loading for multiple spatial streams and methods

• US 7,644,345 B2
• Filed: 01/12/2005
• Issued: 01/05/2010
• Est. Priority Date: 01/12/2005
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Poon, Ada Shuk Yan, Sandhu, Sumeet, Li, Qinghua, Lin, Xintian E, Davydov, Alexei V, Maltsev, Alexander Alexandrovich
• Primary Examiner(s): Lamarre; Guy J
• Assistant Examiner(s): RIZK, SAMIR WADIE
• Application Number:
  US11/034,204
• Publication Number:
  US 20060156087A1
• Time in Patent Office: 1,819 Days
• Field of Search: 714/752, 714/786, 375/260
• US Class Current: 714/786
• CPC Class Codes: H04L 5/0044 allocation of payload

Abstract

In a multicarrier transmitter that transmits two or more spatial data streams, a bit distributor assigns encoded bits to the spatial data streams based on bit-loading capabilities of the streams and in a manner to intermix the bits among the spatial streams.

Claims

1. A bit distributor for use in a transmitter for concurrent transmission of a plurality of streams through two or more spatial channels, comprising:

a calculator to calculate a first delta for a first of the streams and a second delta for a second of the streams; and

a bit extractor to extract a first set of bits for the first stream in a non-sequential manner from an input group of selected input bits,

wherein the bit extractor determines which bits to extract from the input group for the first stream by multiplying a bit index of each bit of the first set by the first delta to determine a bit index of the bit to extract from the input group,

wherein after extraction of the set of bits for the first stream, the bit extractor is configured to sequentially re-label remaining bits of the input group and to extract a second set of bits for the second stream in a non-sequential manner from the relabeled remaining bits,

wherein the bit extractor determines which bits to extract from the relabeled remaining bits for the second stream by multiplying a bit index of each bit of the second set by the second delta to determine a bit index of the bit to extract from the relabeled remaining bits,

wherein the first delta is calculated based on the sum of the bit-loading capabilities of the plurality of streams divided by the bit-loading capability of the first stream, and

wherein the second delta is calculated based on the sum of the bit-loading capabilities of the second and any remaining streams of the plurality divided by the bit-loading capability of the second stream.

2. The bit distributor of claim 1 wherein when the plurality of streams comprises at least a third stream:

the calculator is configured to calculate a third delta is based on the sum of the bit-loading capabilities of the third and any remaining streams of the plurality divided by the bit-loading capability of the third stream; and

the bit extractor is configured to;

sequentially re-label remaining bits of the input group after extraction of the set of bits for the second stream; and

extract a third set of bits for the third stream in a non-sequential manner from the relabeled remaining bits,

wherein the bit extractor determines which bits to extract from the relabeled remaining bits for the third stream by multiplying a bit index of each bit of the third set by the third delta to determine a bit index of the bit to extract from the relabeled remaining bits.

3. The bit distributor of claim 2 wherein each spatial channel utilizes a same set of OFDM subcarriers,

wherein the bit-loading capabilities represent a number of bits per symbol for symbol modulating data subcarriers of each of the streams prior to transmission, and

wherein the bit-loading capabilities are determined from channel conditions for the subcarriers of the spatial channels.

4. The bit distributor of claim 2 wherein the calculator is configured to sort the plurality of streams based on the bit-loading capabilities of the streams,

wherein the first stream has a greatest of the bit-loading capabilities and the second stream has next-greatest of the bit-loading capabilities, and

wherein the bit distributor further comprises a bit selector to select a number of bits for the input group based on the bit-loading capabilities of the plurality of spatial streams.

5. The bit distributor of claim 2 wherein the bit distributor is part of a multicarrier transmitter that includes an interleaver for each stream to perform separate interleaving operations on the bits of the streams that are generated by the bit interleaver.

6. A method of distributing bits among a plurality of streams for concurrent transmission through two or more spatial channels sharing a same frequency spectrum, the method comprising:

calculating a first delta for a first of the streams and a second delta for a second of the streams;

extracting a first set of bits in a non-sequential manner for the first stream from an input group of selected input bits, the extracting comprising determining which bits to extract from the input group for the first stream by multiplying a bit index of each bit of the first set by the first delta to determine a bit index of the bit to extract from the input group;

sequentially re-labeling remaining bits of the input group after the extraction of the first set;

extracting a second set of bits for the second stream in a non-sequential manner from the relabeled remaining bits, wherein extracting comprises determining which bits to extract from the relabeled remaining bits for the second stream by multiplying a bit index of each bit of the second set by the second delta to determine a bit index of the bit to extract from the relabeled remaining bits,

wherein the first delta is calculated based on the sum of the bit-loading capabilities of the plurality of streams divided by the bit-loading capability of the first stream, and

wherein the second delta is calculated based on the sum of the bit-loading capabilities of the second and any remaining streams of the plurality divided by the bit-loading capability of the second stream.

7. The method of claim 6 wherein when the plurality of streams comprises a third stream, the method further comprises:

calculating a third delta is based on the sum of the bit-loading capabilities of the third and any remaining streams of the plurality divided by the bit-loading capability of the third stream;

sequentially re-labeling remaining bits of the input group after extraction of the set of bits for the second stream; and

extracting a third set of bits for the third stream in a non-sequential manner from the relabeled remaining bits, wherein the extracting comprises determining which bits to extract from the relabeled remaining bits for the third stream by multiplying a bit index of each bit of the third set by the third delta to determine a bit index of the bit to extract from the relabeled remaining bits.

8. The method of claim 7 wherein each spatial channel utilizes a same set of OFDM subcarriers,

wherein the bit-loading capabilities represent a number of bits per symbol for symbol modulating data subcarriers of each of the streams prior to transmission,

wherein the bit-loading capabilities are determined from channel conditions for the subcarriers of the spatial channels, and

wherein the method further comprises changing the bit-loading capabilities dynamically in response to changing channel conditions.

9. The method of claim 7 further comprising:

sorting the plurality of streams based on the bit-loading capabilities of the streams; and

selecting a number of bits for the input group based on the bit-loading capabilities of the plurality of spatial streams,

wherein the first stream has a greatest of the bit-loading capabilities and the second stream has next-greatest of the bit-loading capabilities.

10. The method of claim 7 further comprising providing output groups of bits for each stream in accordance with the ratio of the bit-loading capabilities of the plurality of streams.

11. A multicarrier transmitter configured to concurrently transmit a plurality of streams through two or more spatial channels, the multicarrier transmitter comprising:

first stream mapping circuitry to map bits of a first stream to symbols in accordance with subcarrier modulation assignments for the first stream;

second stream mapping circuitry to map bits of a second stream to symbols in accordance with subcarrier modulation assignments for the second stream; and

a bit distributor to generate the first and second streams from an input bit stream,

wherein the bit distributor comprises;

a calculator to calculate a first delta for the first stream and a second delta for the second stream; and

a bit extractor to extract a first set of bits for the first stream in a non-sequential manner from an input group of selected input bits of the input bit stream,

wherein the bit extractor determines which bits to extract from the input group for the first stream by multiplying a bit index of each bit of the first set by the first delta to determine a bit index of the bit to extract from the input group,

wherein after extraction of the set of bits for the first stream, the bit extractor is configured to sequentially re-label remaining bits of the input group and to extract a second set of bits for the second stream in a non-sequential manner from the relabeled remaining bits, and

wherein the bit extractor determines which bits to extract from the relabeled remaining bits for the second stream by multiplying a bit index of each bit of the second set by the second delta to determine a bit index of the bit to extract from the relabeled remaining bits,

wherein the first delta is calculated based on the sum of the bit-loading capabilities of the plurality of streams divided by the bit-loading capability of the first stream, and

wherein the second delta is calculated based on the sum of the bit-loading capabilities of the second and any remaining streams of the plurality divided by the bit-loading capability of the second stream.

12. The multicarrier transmitter of claim 11 wherein each spatial channel utilizes a same set of OFDM subcarriers.

13. The multicarrier transmitter of claim 12 wherein when the plurality of streams comprises a third stream:

the calculator is configured to calculate a third delta is based on the sum of the bit-loading capabilities of the third and any remaining streams of the plurality divided by the bit-loading capability of the third stream; and

the bit extractor is configured to sequentially re-label remaining bits of the input group after extraction of the set of bits for the second stream, and extract a third set of bits for the third stream in a non-sequential manner from the relabeled remaining bits,

wherein the bit extractor determines which bits to extract from the relabeled remaining bits for the third stream by multiplying a bit index of each bit of the third set by the third delta to determine a bit index of the bit to extract from the relabeled remaining bits.