Method and apparatus for diversity reception of time-dispersed signals

Abstract

A method and appartus for diversity reception in a communication system wherein at least a dual branch receiver is provided with a stored replica of expected reference information that is correlated with the received time-dispersed signals to obtain an estimate of the transmission channel's impulse response as seen by each branch, and determine, among other things, phase error between the branch local oscillators and the time-dispersed signals. Matched filters are constructed which then coherently align the time-dispersed signals from each branch with that branch's local oscillator, also constituting the first part of the equalization. The diversity processing stage may perform bit by bit selection on the re-aligned signals, maximal ratio combining of the re-aligned signals, or equal gain combining of the re-aligned signals, following each by a sequence estimation which uses similarly selected or combined channel distortion compensation parameters to complete the equalization process on the new signal. In digital modulated carrier systems, providing expected reference information eliminates the neeed for carrier recovery feedback for each branch while performing part of the equalization process.