Design and implementation of an efficient point slicing algorithm for the V.34 modem standard

The V.34 modem standard uses QAM constellations with 4 to 1664 points depending upon the results of the line probing where the telephone channel is characterized to connect at the maximum possible data rate. In the receiver, the decisions errors due to the channel noise are prevented by using the Viterbi subset decoder which uses a point slicing algorithm that determines the closest valid point on the constellation for a given constellation size. In this paper we present a point slicing algorithm where the complexity is nearly independent of the QAM constellation size