A Method for Accessing Spatial Spectrum Holes for Relay Based Cognitive Cellular Networks

In cellular networks, usually users at the cell edge experience degraded Quality-of-Service (QoS) due to poor signal strength and severe interference. This paper attempts to resolve this issue by applying cognitive radio features to a relay based cellular network. Spatial holes in the spectrum, licensed to another (primary) network, are accessed for relaying purpose such that the outage probability of the cumulative interference to primary users is below limit. This relaxes the requirement for bandwidth reservation needed for conventional relaying. Moreover, interference from adjacent cells in relay to user link is eliminated which leads to extended coverage for such cognitive relays. The method is tested in a simulated TD-LTE sub-urban scenario and found to outperform the conventional relaying.