Packet buffer management apparatus and method

Abstract

A reduced complexity maximum likelihood decoder receives a stream of received symbols Y accompanied by a channel estimate matrix H. A variable transformation part includes a first part which converts Y and H into Z and R by computing a matrix R having at least one non-zero element in a row, such that the product of R and Q produces matrix H. A second variable transformation part column-swaps matrix H to form H', thereafter generating Q′ and R′ subject to the same constraints as was described for Q and R. Transformed variables Z and Z′ are formed by multiplying Y by Qand Q′, respectively. A reduced complexity maximum likelihood decoder has a first part which accepts Z and R and forms a first metric table having entries of all possible x2 accompanied by estimates of xderived from xand Z, and also including a distance metric. The reduced complexity maximum likelihood decoder has a second part which accepts Z′ and R′ and forms a second metric table having entries of all possible xaccompanied by estimates of xderived from xand Z′, and also including a distance metric. A hard decision is made by finding the minimum distance metric of the combined entries of the first and second table. Soft values are also computed using this table.