Broadcom Corporation

Avago Technologies General IP (singapore) Pte. Ltd.

Hau Thien Tran

Kelly Brian Cameron

Ba-Zhong Shen

Tak Kwan Lee

Christopher R Jones

Christopher J Hansen

Nambirajan Seshadri

Jason A Trachewsky

Scott R Powell

Thomas A Hughes, Jr

Joseph Paul Lauer

Thomas Ashford Hughes, Jr

Jonathan S Min

Avi Kliger

Gottfried Ungerboeck

Leo Montreuil

Richard Stephen Prodan

Thomas A Hughes

James A Trachewsky

Linda K Lau

A wireless local area network (WLAN) transmitter includes a baseband processing module and a plurality of radio frequency (RF) transmitters. The processing module selects one of a plurality of modes of operation based on a mode selection signal. The processing module determines a number of transmit streams based on the mode selection signal. The processing of the data further continues by converting encoded data into streams of symbols in accordance with the number of transmit streams and the mode selection signal. A number of the plurality of RF transmitters are enabled based on the mode selection signal to convert a corresponding one of the streams of symbols into a corresponding RF signal such that a corresponding number of RF signals is produced.

WLAN transmitter having high data throughput

The present disclosure presents symbol mapping for any desired error correction code (ECC) and/or uncoded modulation. A cross-shaped constellation is employed to perform symbol mapping. The cross-shaped constellation is generated from a rectangle-shaped constellation. Considering the rectangle-shaped constellation and its left hand side, a first constellation point subset located along that left hand side are moved to be along a top of the cross-shaped constellation while a second constellation point subset located along that left hand side are moved to be along a bottom of the cross-shaped constellation. For example, considering an embodiment having four constellation point subsets along the left hand side of the rectangle-shaped constellation, two of those subsets are moved to be along the top of the cross-shaped constellation while two other subsets of the constellation points along the left hand side are moved to be along the bottom of the cross-shaped constellation.

Symbol mapping for binary coding

A communication device is configured adaptively to process a receive signal based on noise that may have adversely affected the signal during transition via communication channel. The device may be configured to identify those portions of the signal of the signal that are noise-affected (e.g., noise-affected sub-carriers of an orthogonal frequency division multiplexing (OFDM) signal), or the device may receive information that identifies those portions of the signal that are noise-affected from one or more other devices. The device may be configured to perform the modulation processing of the received signal to generate log-likelihood ratios (LLRs) for use in decoding the signal. Those LLRs associated with noise-affected portions of the signal are handled differently than LLRs associated with portions of the signal that are not noise-affected. The LLRs may be scaled based on signal to noise ratio(s) (SNR(s)) associated with the signal (e.g., based on background noise, burst noise, etc.).

Adaptive decoding based on signal to noise ratio (SNR)

Rate control adaptable communications. A common trellis is employed at both ends of a communication system (in an encoder and decoder) to code and decode data at different rates. The encoding employs a single encoder whose output bits may be selectively punctured to support multiple modulations (constellations and mappings) according to a rate control sequence. A single decoder is operable to decode each of the various rates at which the data is encoded by the encoder. The rate control sequence may include a number of rate controls arranged in a period that is repeated during encoding and decoding. Either one or both of the encoder and decoder may adaptively select a new rate control sequence based on a variety of operational parameters including operating conditions of the communication system, a change in signal to noise ratio (SNR), etc.

Rate control adaptable communications

Variable modulation within combined LDPC (Low Density Parity Check) coding and modulation coding systems. Variable modulation encoding of LDPC coded symbols is presented. In addition, LDPC encoding, that generates an LDPC variable code rate signal, may also be performed as well. The encoding can generate an LDPC variable code rate and/or modulation signal whose code rate and/or modulation may vary as frequently as on a symbol by symbol basis. Some embodiments employ a common constellation shape for all of the symbols of the signal sequence, yet individual symbols may be mapped according different mappings of the commonly shaped constellation; such an embodiment may be viewed as generating a LDPC variable mapped signal. In general, any one or more of the code rate, constellation shape, or mapping of the individual symbols of a signal sequence may vary as frequently as on a symbol by symbol basis.

Variable modulation with LDPC (low density parity check) coding

LDPC (Low Density Parity Check) codes with corresponding parity check matrices selectively constructed with CSI (Cyclic Shifted Identity) and null sub-matrices. An LDPC matrix corresponding to an LDPC code is employed within a communication device to encode and/or decode coded signals for use in any of a number of communication systems. The LDPC matrix is composed of a number of sub-matrices and may be partitioned into a left hand side matrix and a right hand side matrix. The right hand side matrix may include two sub-matrix diagonals therein that are composed entirely of CSI (Cyclic Shifted Identity) sub-matrices; one of these two sub-matrix diagonals is located on the center sub-matrix diagonal and the other is located just to the left thereof. All other sub-matrices of the right hand side matrix may be null sub-matrices (i.e., all elements therein are values of zero '0').

LDPC (Low Density Parity Check) codes with corresponding parity check matrices selectively constructed with CSI (Cyclic Shifted Identity) and null sub-matrices

True bit level decoding of TTCM (Turbo Trellis Coded Modulation) of variable rates and signal constellations. A decoding approach is presented that allows for decoding on a bit level basis that allows for discrimination of the individual bits of a symbol. Whereas prior art approaches typically perform decoding on a symbol level basis, this decoding approach allows for an improved approach in which the hard decisions/best estimates may be made individually for each of the individual bits of an information symbol. In addition, the decoding approach allows for a reduction in the total number of calculations that need to be performed as well as the total number of values that need to be stored during the iterative decoding. The bit level decoding approach is also able to decode a signal whose code rate and/or signal constellation type (and mapping) may vary on a symbol by symbol basis.

True bit level decoding of TTCM (turbo trellis coded modulation) of variable rates and signal constellations

A method for asymmetrical MIMO wireless communication begins by determining a number of transmission antennas for the asymmetrical MIMO wireless communication. The method continues by determining a number of reception antennas for the asymmetrical MIMO wireless communication. The method continues by, when the number of transmission antennas exceeds the number of reception antennas, using spatial time block coding for the asymmetrical MIMO wireless communication. The method continues by, when the number of transmission antennas does not exceed the number of reception antennas, using spatial multiplexing for the asymmetrical MIMO wireless communication.

Asymmetrical MIMO wireless communications

LDPC (Low Density Parity Check) coding and interleaving implemented in multiple-input-multiple-output (MIMO) communication systems. As described herein, a wide variety of irregular LDPC codes may be generated using GRS or RS codes. A variety of communication device types are also presented that may employ the error correcting coding (ECC) using a GRS-based irregular LDPC code, along with appropriately selected interleaving, to provide for communications using ECC. These communication devices may be implemented to in wireless communication systems including those that comply with the recommendation practices and standards being developed by the IEEE 802.11Task Group (i.e., the Task Group that is working to develop a standard for 802.11 TGn (High Throughput)).

LDPC (low density parity check) coding and interleaving implemented in MIMO communication systems

LDPC (low density parity check) codes with corresponding parity check matrices selectively constructed with CSI (cyclic shifted identity) and null sub-matrices

Overlapping sub-matrix based LDPC (Low Density Parity Check) decoder. Novel decoding approach is presented, by which, updated bit edge messages corresponding to a sub-matrix of an LDPC matrix are immediately employed for updating of the check edge messages corresponding to that sub-matrix without requiring storing the bit edge messages; also updated check edge messages corresponding to a sub-matrix of the LDPC matrix are immediately employed for updating of the bit edge messages corresponding to that sub-matrix without requiring storing the check edge messages. Using this approach, twice as many decoding iterations can be performed in a given time period when compared to a system that performs updating of all check edge messages for the entire LDPC matrix, then updating of all bit edge messages for the entire LDPC matrix, and so on. When performing this overlapping approach in conjunction with min-sum processing, significant memory savings can also be achieved.

Overlapping sub-matrix based LDPC (low density parity check) decoder

LDPC (Low Density Parity Check) coded modulation symbol decoding. Symbol decoding is supported by appropriately modifying an LDPC tripartite graph to eliminate the bit nodes thereby generating an LDPC bipartite graph (such that symbol nodes are appropriately mapped directly to check nodes thereby obviating the bit nodes). The edges that communicatively couple the symbol nodes to the check nodes are labeled appropriately to support symbol decoding of the LDPC coded modulation signal. The iterative decoding processing may involve updating the check nodes as well as estimating the symbol sequence and updating the symbol nodes. In some embodiments, an alternative hybrid decoding approach may be performed such that a combination of bit level and symbol level decoding is performed. This LDPC symbol decoding out-performs bit decoding only. In addition, it provides comparable or better performance of bit decoding involving iterative updating of the associated metrics.

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Irvine, CA, United States of America

Hau Thien Tran