Title :
Partial and Opportunistic Relay Selection with Outdated Channel Estimates
Author :
Soysa, Madushanka ; Suraweera, Himal A. ; Tellambura, Chintha ; Garg, Hari K.
Author_Institution :
Dept. of Electr. & Comput. Eng., Univ. of California at San Diego, La Jolla, CA, USA
fDate :
3/1/2012 12:00:00 AM
Abstract :
This paper investigates the impact of using outdated channel estimates for relay selection and signal amplification on the performance of amplify-and-forward (AF) relays under partial relay selection (PRS) and opportunistic relay selection (ORS). In practice, outdated channel state information (CSI) can occur due to feedback or scheduling delay. Both variable gain (VG) AF and fixed gain AF schemes are considered. Outage probability, the average bit error rate (BER) and simplified high signal-to-noise ratio approximations are derived. The effect of parameters such as the number of relays, the rank of chosen relay, and the correlation between the delayed and current channel state information are analyzed. Outdated CSI for computing relay gains in PRS causes about 2 dB loss. In ORS, a 3% reduction in correlation causes up to an order of magnitude increase in the outage probability.
Keywords :
amplify and forward communication; correlation methods; error statistics; scheduling; amplify-and-forward relays; bit error rate; correlation reduction; feedback; opportunistic relay selection; outdated channel estimates; outdated channel state information; partial relay selection; scheduling delay; signal amplification; uutage probability; Approximation methods; Bit error rate; Channel estimation; Educational institutions; Gain; Relays; Signal to noise ratio; Relay selection; amplify-and-forward; error performance; outage probability; outdated channel state information;
Journal_Title :
Communications, IEEE Transactions on
DOI :
10.1109/TCOMM.2012.12.100671
