Patent ID: 6947506
Filing Date: 2005-09-20
Classification: H04L

Abstract:
1. A method for decoding individual blocks of data of a sequence of received interfering signals corrupted by multi-user interference by performing multiple iterations of decoding on the signals to identify the value of signal points for decoding the signals, the method uses a multi-user decoder and a plurality of single user decoders, the multi-user decoder using an algorithm defining a tree diagram having a number of node levels equal to the number of signals from which the signal points are derived, with the first/highest order term of the algorithm being assigned to the first/root node level of the tree, the second/next highest term of the algorithm being assigned to the second node level of the tree, to the last/lowest order term of the algorithm being assigned to the last node level of the tree, and the method for decoding the signals in each block of data comprising the steps of: (a) performing a first decoding of the received interfering signals in a block of data in the multi-user decoder to determine first channel symbol estimates for each of the signals; (b) performing a first decoding of the signals in the block of data in the single user decoders, with each signal being assigned to and processed by a respective one of the single user decoders, and using the first channel symbol estimates determined in step (a) for each signal assigned to a respective one of the single user decoders to determine a first probability estimate for each of the data bits in the signals, the decoding in steps (a) and (b) accomplishing a first iteration of decoding; (c) performing a subsequent decoding of the received interfering signals in a subsequent block of data in the multi-user decoder initially using the first probability estimates determined in step (b) for each of the signals, after assigning the signal that has a probability estimate closest to a predetermined value to the first term of the algorithm, assigning the signal that has a probability estimate next closest to the predetermined value to the second term of the algorithm, to assigning the signal that has a probability estimate furthest from the predetermined value to the last term of the algorithm, to determine a revised channel symbol estimate for each of the channel symbols; (d) performing a subsequent decoding of the signals in the subsequent block of data in the single user decoders, with each signal being assigned to and processed by a respective one of the single user decoders, and using the revised channel symbol estimates determined in step (c) for each signal assigned to a respective one of the single user decoders to determine a revised probability estimate of the data bits for each of the signals, the decoding in steps (c) and (d) accomplishing a second iteration of decoding; (e) repeating steps (c) and (d) for third and subsequent iterations of decoding, with channel symbol estimates for each iteration of decoding determined in step (c) being used by the single user decoders in step (d), and revised data bit probability estimates for each iteration of decoding determined in step (d) being used is step (c); and (f) decoding the signals in the block of data using the value of signal points determined as a result of the iterative decoding steps (a)-(e), wherein the iterative decoding steps (a)-(e) using different probability estimates determined during each iteration of decoding improves tree construction and tree pruning to reduce signal processing time to a minimum.