QoS-Based Multi-criteria Handoff Algorithm for Femto-Macro Cellular Networks

The hierarchical coexistence of femtocells and macrocells is a promising approach for heterogeneous networks (HetNets), dealing mainly with indoor coverage issues and providing high data rates in cellular networks. As for any HetNet, mobility management with handoff issues on top, should be studied prior to hindering the successful deployment of these networks. The current study introduces a new handoff algorithm in hierarchical macro/femtocell HetNets based on the combination of quality of service metrics for efficient network selection including: received signal strength, co-channel interference level, and outage probability of each of femtocell and macrocell networks. The proposed algorithm first collects the measured three mentioned metrics based on mobile station (MS) location, then applies a dynamic weighting system to three-metric sets according to the significance of each metric to obtain one utility for each of femtocell and macrocell networks. The obtained utility is then used as a measure for determining handoff necessity. In order to evaluate the performance of the proposed approach, the paper then introduces analytical model of cell assignment probability for an MS moving from the serving macrocell base station to the target femtocell base station in a two-tier cellular network. The analytical and simulation results indicate the efficiency of the proposed handoff algorithm in comparison with the existing algorithms in terms of cell assignment probability, throughput, number of handoffs, and ping-pong rate.