Abstract
The HetNet architecture is considered to be one of the promising solutions for the problem of capacity crunch and increasing energy consumption of wireless communication networks. Hence, it is expected to be one of the key aspects in the realisation of the future wireless communication networks. Moreover, future wireless communication networks are characterised by the co-existence of multiple radio access technologies called multi-RAT HetNets. In this context, the integrated cellular-WLAN HetNet attracts considerable interest among the mobile network operators. One of the major challenges of such HetNet is the optimal selection of serving network. In this regard, this thesis focuses on the efficient network selection schemes for an operator deployed cellular-WLAN HetNet. Firstly, a novel load balancing scheme is proposed for an operator deployed cellular-WLAN HetNet, where the user association is controlled by employing cell-breathing technique for the WLAN network. In this scheme, the coverage of each WiFi AP is dynamically optimised to achieve desired load balancing. Since this is a network controlled traffic steering scheme, users can simply associate to the available strongest WiFi AP, without making any complex network selection decisions. Thus, can be easily implemented in an existing cellular-WLAN HetNet. Subsequently, performance analysis of cellular-WLAN HetNet is carried out for a saturated downlink scenario, in order to investigate the effect of deploying CRE technique for WLAN network in the cellular-WLAN HetNet. In addition, a cellular-WLAN interworking architecture and detailed signalling procedures are proposed for implementing CRE scheme in an operator deployed cellular-WLAN HetNet. Finally, a novel Adaptive Stochastic Radio Access Selection scheme is proposed for an operator deployed cellular-WLAN HetNet. This scheme implements a stochastic network selection policy that assigns certain probability for selecting WLAN according to the status of the network in terms of load and signal quality. The proposed scheme helps to improve the system performance in terms of network throughput, energy efficiency, and call blocking probability.