Joint time offset and fading channel coefficient estimation for cooperative communication systems

In this paper, we investigate joint channel gain and time offset estimation for two different data aided methods in cooperative communication with amplify-and-forward (AF) relaying. First one is the Cascaded Estimation (CE) method which channel gain, and time offset consisting of both source-to-relay, and relay-to-destination links are estimated at the destination terminal, second one is Disintegrated Estimation (DE) method which channel gain, and time offset are estimated seperately at the relay for source-to-relay link, and at the destination for relay-to-destination link. Both of the proposed joint estimators are based on Expectation-Maximization (EM) algorithm and, produce a low-complexity solution of itaretive maximum likelihood (ML) estimation. It was observed by the bit error rate (BER) curves, the proposed methods provide good performances with low-complexity.