Constructions of Cooperative Diversity Schemes for Asynchronous Wireless Networks

It has been shown by Li and Xia that there exist cooperative diversity schemes that can provide for diversity gains in wireless networks even without symbol synchronicity between cooperative network users. These asynchronicity-tolerant schemes were based on distributed space-time codes which maintained their full-rank property for specific asynchronicity cases and specific numbers of users. By expanding the signaling set, we provide constructions of schemes that maintain near-optimal error performance, given certain cooperation strategies and given synchronicity, and which are asynchronicity-tolerant, with probability one, for any asynchronicity profile and for all numbers of network users. By relating the problem of asynchronicity to the maximum degrees of freedom provided by a cooperative-diversity scheme, we are further able to provide cooperative diversity methods that are empirically shown to translate asynchronicity to reduction of the probability of error.