Amplify-and-Forward Relaying for Reducing Outages in TDMA-Based WPANs Operating in Unlicensed Bands

Diversity is of particular advantage for wireless personal area networks (WPANs) operating in unlicensed bands, as it may help to overcome not only channel fades but also cochannel interference. We consider WPANs based on time-division multiple access schemes leaving room for cooperative amplitude-and-forward procedures. A formula for the diversity order is presented assuming optimal combining of the signal observations in the presence of interference. This enables idle WPAN devices to evaluate diversity orders in a distributed fashion, and decide instantaneously whether to assist a particular peer-to-peer transmission. Numerical results show that outages can be considerably reduced by the proposed cooperative methods. Keywords— Cooperative diversity, cochannel interference, amplitude-and-forward, diversity order, wireless personal area network.