Delay-diversity in multi-user relay systems with Interleave Division Multiple Access

In this paper, a new combination of a multiple access scheme and spatial diversity offered by relays is proposed. In order to support several users in a system, interleave division multiple access (IDMA) is suggested here due to the capability to deal with asynchronous transmission by the users. The relays apply amplify-and-forward combined with delay-diversity in order to exploit the spatial diversity without the need of synchronization of the relays. Furthermore, the IDMA detector can easily be extended to utilize the diversity very efficiently. So this combination of basic approaches can deal with asynchronous transmission of the users and the relays, respectively, resulting in a very flexible system with small signaling overhead.