Event Details
Low Complexity Timing Synchronization for Decode-and-Forward Cooperative Communication Systems with Multiple Relays
Presenter: Yuzhe Yao
Supervisor: Dr. Xiaodai Dong
Date: Mon, July 23, 2012
Time: 13:00:00 - 00:00:00
Place: EOW 430
ABSTRACT
ABSTRACT
In this seminar, timing synchronization for a decode-and-forward (DF) cooperative communication system with a single source, destination and multiple relays will be discussed. Timing estimation in the multiple access phase from the relays to the destination involves multiple parameters associated with different relays. The existing maximum likelihood (ML) estimator needs exhaustive search over the estimation range, and the complexity of the ML estimator increases exponentially as the number of relays or the resolution increases. We consider a correlation based timing estimator to save computational complexity. The proposed method requires that each relay transmits a Pseudorandom Noise (PN) sequence as the training symbols for synchronization. At the destination, the discrete superimposed signal is first interpolated to the required resolution and then correlated with each relay's PN sequence modulated waveform template sampled at the same resolution. The peak of each correlation yields the estimation of the delay for the corresponding relay. The correlation output at the peak also provides an estimation of the fading channel, which can be seen as a by-product of the timing estimator. The proposed timing estimator saves substantial complexity compared to the ML estimator and is able to achieve satisfactory performance, which is demonstrated by the simulation results.