Modified branch metrics for processing bit-soft decisions to account for
phase noise impact on cluster variance (CV). The present invention is
able to partition a modulation scheme's constellation into two or more
regions, so that the bit-soft decision branch metrics may be adjusted
based on the CV of the various constellation points. A confidence level
may be attached to the various constellation points based on their
particular CVs. There are a number of methods to ascertain the CV of the
constellation's points, including finding characteristics of various
components in a communication system (transmitter, communication channel
and receiver), and any method may be used within various embodiments. The
modification of the branch metrics/confidence level may be performed in a
communication receiver; the communication receiver may be implemented in
a communication system employing the vector orthogonal frequency division
multiplexing (VOFDM) portion of the broadband wireless internet forum
(BWIF).