摘要:
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.
摘要:
Implementation of LDPC (Low Density Parity Check) decoder by sweeping through sub-matrices. A novel approach is presented by which an LDPC coded signal is decoded processing the columns and rows of the individual sub-matrices of the low density parity check matrix corresponding to the LDPC code. The low density parity check matrix can partitioned into rows and columns according to each of the sub-matrices of it, and each of those sub-matrices also includes corresponding rows and columns. For example, when performing bit node processing, the same columns of at 1 or more sub-matrices can be processed together (e.g., all 1st columns in 1 or more sub-matrices, all 2nd columns in 1 or more sub-matrices, etc.). Analogously, when performing check node processing, the same rows of 1 or more sub-matrices can be processed together (e.g., all 1st rows in 1 or more sub-matrices, all 2nd rows in 1 or more sub-matrices, etc.).
摘要:
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.
摘要:
LDPC (Low Density Parity Check) coded modulation hybrid decoding. A novel approach is presented wherein a combination of bit decoding and symbol level decoding (e.g., hybrid decoding) is performed for LDPC coded signals. Check node updating and symbol node updating are successively and alternatively performed on bit edge messages for a predetermined number of decoding iterations or until a sufficient degree of precision is achieved. The symbol node updating of the bit edge messages involves using symbol metrics corresponding to the symbol being decoded as well as the bit edge messages most recently updated by check node updating. The check node updating of the bit edge messages involves using the bit edge messages most recently updated by symbol node updating. The symbol node updating also involves computing possible soft symbol estimates for the symbol during each decoding iteration.
摘要:
System correcting random and/or burst errors using RS (Reed-Solomon) code, turbo/LDPC (Low Density Parity Check) code and convolutional interleave. A novel approach is presented that combines different coding types within a communication system to perform various types of error correction. This combination of accommodating different coding types may be employed at either end of a communication channel (e.g., at a transmitter end when performing encoding and/or at a receiver end when performing decoding). By combining different coding types within a communication system, the error correcting capabilities of the overall system is significantly improved. The appropriate combination of turbo code and/or LDPC code along with RS code allows for error correction or various error types including random error and burst error (or impulse noise).
摘要:
LDPC (Low Density Parity Check) coded signal decoding using parallel and simultaneous bit node and check node processing. This novel approach to decoding of LDPC coded signals may be described as being LDPC bit-check parallel decoding. In some alternative embodiment, the approach to decoding LDPC coded signals may be modified to LDPC symbol-check parallel decoding or LDPC hybrid-check parallel decoding. A novel approach is presented by which the edge messages with respect to the bit nodes and the edge messages with respect to the check nodes may be updated simultaneously and in parallel to one another. Appropriately constructed executing orders direct the sequence of simultaneous operation of updating the edge messages at both nodes types (e.g., edge and check). For various types of LDPC coded signals, including parallel-block LDPC coded signals, this approach can perform decoding processing in almost half of the time as provided by previous decoding approaches.
摘要:
Efficient design to implement LDPC decoder. The efficient design presented herein provides for a solution that is much easier, smaller, and has less complexity than other possible solutions. The use of a ping-pong memory structure (or pseudo-dual port memory structure) in conjunction with a metric generator near the decoder's front end allows parallel bit/check node processing. An intelligently operating barrel shifter operates with a message passing memory that is operable to store updated edges messages with respect to check nodes as well as updated edges messages with respect to bit nodes. Using an efficient addressing scheme allows the same memory structure to store the two types of edges messages with respect to bit nodes: (1) corresponding to information bits and (2) corresponding to parity bits. In addition, an intelligently designed hardware macro block may be instantiated a number of times into the decoder design to support ever greater design efficiency.
摘要:
Amplifying magnitude metric of received signals during iterative decoding of LDPC code and LDPC coded modulation. By appropriately selecting a metric coefficient value that is used to calculate the initial conditions when decoding LDPC coded signals, a significant reduction in BER may be achieved at certain SNRs. The appropriate selection of the metric coefficient value may be performed depending on the particular SNR at which a communication system is operating. By adjusting this metric coefficient value according to the given LDPC code, modulation, and noise variance, the overall performance of the decoding may be significantly improved. The convergence speed is slowed down so that the decoder will not go to the wrong codeword, and the moving range of the outputs of the decoder is restricted so that the output will not oscillate too much and will eventually move to the correct codeword.
摘要:
Low Density Parity Check (LDPC) code decoder using min*, min**, max* or max** and their respective inverses. For the first time, min* processing is demonstrated for use in decoding LDPC-coded signals. In addition, max*, min**, or max** (and their respective inverses) may also be employed when performing calculations that are required to perform decoding of signals coded using LDPC code. These new parameters may be employed to provide for much improved decoding processing for LDPC codes when that decoding involves the determination of a minimal and/or maximal value, or a minimal and/or maximal log corrected value, from among a number of possible values. The total number of processing steps employed within the decoding of an LDPC-coded signal is significantly reduced be employing the min*, max*, min**, or max** (and their respective inverses) decoding processing described herein.
摘要:
Symbol by symbol variable constellation type and/or mapping capable communication device. A communication device is operable to perform processing of a variable constellation signal whose constellation varies on a symbol by symbol basis. This may involve performing encoding of input to generate the variable constellation signal; alternatively or in addition to, this may involve performing decoding of a variable constellation signal as well. In doing so, this approach may involve using a single encoder and/or decoder (depending on the application). In some instances, a single device is operable to encode a first variable constellation signal (for transmission to another device) and to decode a second variable constellation signal (that has been received from another device). In addition, a method of coding (including one or both of encoding and decoding) may also operate of a variable constellation signal whose constellation varies on a symbol by symbol basis.