A survey of handover management in LTE-based multi-tier femtocell networks: Requirements, challenges and solutions

Ubiquitous mobile communication requires increased capacity and appropriate quality guarantee for services. To meet these demands next-generation mobile network operators will deploy small cells next to conventional base station structure intensively to enhance capacity and service coverage for customers. Implementation of seamless handover between first tier (macrocell layer) and second tier (small cells) is one of the key challenges to fulfill the QoS requirements. In this paper we introduce the reader to the details of the handover procedure: information gathering, decision strategies and the base station exchange process. All these three phases face difficulties in multi-tier networks. High dense femtocell deployment makes handover related information gathering very hard, efficient handover decision mechanisms are vital to reduce the number of unnecessary handovers and avoid ping-pong effect. Last but not least base station exchange has to be accelerated to achieve appropriate system performance. Next a comprehensive survey of state of the art handover optimization solutions in 3GPP LTE/LTE-A Home eNodeB handover management is presented which includes the actual version of 3GPP LTE/LTE-A HeNB handover procedure.