Downlink Channel Allocation Scheme deploying Cooperative Channel Monitoring for Cognitive Cellular-FemtocellNetworks

Cognitive cellular-femtocell networks are considered as future mobile communication networks which can satisfy challenging requirements of current mobile communications including high user density, quality of service (QoS) provision and efficient spectrum utilization. In this paper, we present a novel downlink channel allocation scheme which allocates downlink channels to new connection requests of real-time connections in cognitive cellular-femtocell networks. In the scheme, a cognitive femtocell access point (CFAP) cooperates with other 2-hop neighbor CFAPs to establish a cooperative channel monitoring group for monitoring and exchanging information of channel occupancy among the CFAPs belonging to the group. Upon receiving a new connection request from a femtocell user (FU), the serving CFAP uses the information of channel occupancy updated from neighboring CFAPs and interference level of channels to allocate a channel, which is expected to cause the minimum interference to macro users (MUs) of the covering macro base station (MBS). Simulation results prove that the proposed scheme can provide better performance than the conventional downlink channel allocation scheme which does not exploit the cooperation of CFAPs in channel monitoring.