Patent ID: 8582677

Claim:
A communication apparatus, comprising: a transmission pattern generation unit that generates a transmission pattern according to a modulation method; a metric calculation unit that calculates an inter-signal distance between a received signal vector of signals received by a plurality of antennas and an estimation vector, which is a product of channel information and the transmission pattern; a maximum likelihood pattern determination unit that determines a maximum likelihood signal pattern from the inter-signal distance calculated by the metric calculation unit; and an error estimation unit that estimates a phase error component and an amplitude error component contained in the received signal vector, wherein the metric calculation unit calculates the inter-signal distance between the received signal vector and the estimation vector by using the phase error component and/or the amplitude error component estimated by the error estimation unit; the metric calculation unit determines an upper limit, a lower limit, and a step size of the phase error component and the amplitude error component in accordance with resistance of the modulation method to calculate the inter-signal distance between the received signal vector and the estimation vector; and the metric calculation unit applies an optimum solution search algorithm to reduce a number of searches for calculating the inter-signal distance.