主权项 |
1. A system for simple greedy scheduling of check node equation updates, for at least M equations, where 1<M≦N−K, during an iteration in decoding of codes of length N that include a message of K bits represented by a parity check matrix with N−K parity check rows representing check nodes and N columns representing variable nodes, the system comprising:
a de-mapper configured to receive a modulation signal comprising symbols, and convert the modulation signal into coded bit log-likelihood ratios; and at least one decoder coupled to the de-mapper, wherein the at least one decoder is configured to receive the coded bit log-likelihood ratios from the de-mapper, and iteratively perform message passing among variable nodes and check nodes by selecting to update check node equations that minimize bit errors so as to generate a decoded signal comprising bits, the at least one decoder is further configured to:
a. for each check node i, out of M check nodes of the parity check matrix, calculate Vali=Min1+Min2, i=1, 2, . . . , L where L≧1 and where Min1 and Min2 are the two smallest values in a set of absolute values of variable-to-check messages {|MVC(i,:)|} where index i corresponds to the set of check nodes,b. sort the set {Vali} calculated in step a in decreasing order to obtain an ordering vector I={I1, I2, . . . , IM}, such that I1 is the index of a check node with the largest value Val, I2 is the index of a check node with the next largest value Val and IM is the index of a check node with the smallest value Val,c. generate updated M check node equations as MVCnew, according to the ordering vector, I={I1, I2, . . . , IM} calculated in step b, by calculating and propagating corresponding check-to-variable messages,d. identify a valid codeword associated with a parity check equation based on the updated variable-to-check messages MVCnew, ande. output the generated decoded signal. |