A technique to exploit cooperation for packet retransmission in wireless ad hoc networks

• Published in: Journal of communications and networks Vol. 10; no. 2; pp. 148 - 155
• Main Authors: Kim, Haesoo, Buehrer, R. Michael
• Format: Journal Article
• Language: English
• Published: Editorial Department of Journal of Communications and Networks 01.06.2008; 한국통신학회
• Subjects: Array signal processing; Automatic repeat request; Cooperative communications; distributed beamforming; Estimation error; Frequency estimation; packet retransmission; Random variables; Signal to noise ratio; Synchronization; 전자/정보통신공학
• ISSN: 1229-2370; 1976-5541
• DOI: 10.1109/JCN.2008.6389834

In wireless data communication systems, retransmission of an erroneous packet is inevitable due to the harsh communication environment. In this paper, an efficient retransmission scheme using cooperation from neighboring nodes is investigated. In the cooperative retransmission scheme, an erroneous packet is transmitted to the destination by cooperative nodes which have favorable channels. This cooperative retransmission scheme requires no a priori information of neighboring nodes and has no limitation on the number of cooperating nodes. Distributed beamforming is used to accommodate multiple cooperating nodes. Phase and frequency offsets of cooperating signals are extracted from the NACK message and used to co-phase retransmitted data packets. The outage probability of the cooperative retransmission scheme is analyzed for the case of perfect synchronization and when the offsets are estimated. To reduce the impact of the residual phase and frequency offsets in cooperating signals, a low-rate feedback scheme is also investigated. It is shown that improved outage probability and reduced packet error rate (PER) performance can be achieved even for long data packets. The proposed cooperative retransmission scheme is found to outperform simple retransmission by the source as well as decode-and-forward cooperation.