DELAY-TOLERANT WIRELESS NETWORK PROTOCOL WITH LQ-ARQ MECHANISM

In cooperative strategy selection cooperation is an attractive method for its simplicity. ARQ mechanism can bring additional diversity benefit for wireless networks. To develop more powerful cooperative schemes for delay-tolerant wireless networks we combine the distributed selection cooperation protocols with ARQ mechanism and from that analyze their performance from the perspective of diversity-multiplexing- delay (D-M-D) tradeoff. For small networks where any two nodes have direct links, we investigate the general ARQ scheme which directly extends the selection cooperation protocol with single round of feedback to multiple rounds. We show that the D-M-D tradeoff is determined by the ability of relays in signal combining and demonstrate that allowing relays to perform combining reception can achieve optimal D-M-D tradeoff. For large networks where direct links are limited in the neighbors of each node, we present a diffusion ARQ protocol which can effectively exploit the channels of nodes that have no direct links with the source. To improve the quality, I am going to propose Link Quality aware ARQ (LQ-ARQ) protocol which only retransmits packets from a buffer when the link from the sender to the receiver is relatively good.