Handover is one of the key components in cellular network mobility management and has the most stringent latency requirement on service interruption time since the end-user experience is majorly determined by it. In the design of IMT-Advanced systems, the scalability and flexibility to support various 4G deployments is also very crucial while meeting the latency requirement on handover. This article presents the state-of-the-art handover schemes considering various deployment scenarios in IMTAdvanced candidate systems with a focus on IEEE 802.16m1 based next-generation WiMAX networks and 3GPP LTE-Advanced.2 Also, to minimize and optimize handover latency to fulfill the requirement for quality of service during handover, various procedural advanced handover schemes are being developed, proposed, and analyzed by IEEE 802.16m and 3GPP. Handover schemes in IEEE 802.16m and 3GPP provide lower link layer handover latency while providing the required QoS level than the existing link layer handover schemes.
