Research On Handover Protocol Of LTE And WLAN Heterogeneous System Interconnection

Recently, due to its high-speed data rate, the wireless local area network (WLAN) has been widely used as hotspot of small region in IP network converage. In the last two years, the academic research and progress in business operation mode of heterogeneous networks indicates that the convergence of WLAN working as coverage in local hotsopt and 3G/4G cellular network has become a necessity in the future wireless communication. In the process of heterogeneous networking, LTE-WLAN heterogeneous handover mechanism which is one of the core issues about interconnected heterogeneous networks, will become an important emphasis in research. This paper is based on the analysis of LTE protocol stack and WLAN protocol, which leads to in-depth insight of the LTE-WLAN heterogeneous handover mechanism,.Based on projects"The Research And Evaluation Of New Type Radio Resource Management in IMT-Advanced"and"The Research of Cooperative Multicast technology in IMT-Advanced",this thesis studies the current heterogeneous handover mechanism in two aspects: system architecture and protocol layers. Analysis demonstrates that in current 3GPP's LTE-WLAN heterogeneous handover scheme the LTE-WLAN mobility anchor is set in the packet data agteway (P-GW) of LTE core network. Heterogeneous handover at the network layer is supported by using the extended mobile IP protocol such as proxy Mobile IP (PMIP) protocol or dual stack Mobile IP (DSMIP) protocol. However, these methods can not support smooth handoff without packet loss, lead to the problem of user location real-time management in the process of heterogeneous handover, and impact the signaling process in user-equipment heavily.This paper introduces a LTE-WLAN heterogeneous handover scheme to the questions above, based on in-depth analysis about of LTE protocol stack and LWAN protocol. Its core idea is to transfer pakcets from layers above MAC in LTE air interface protocol stack through the WLAN wireless transmission link, by utilizing the WLAN tunnel to encapsulate and deliver the packet data unit (PDU) of Radio Link Control(RLC) in LTE protocol. This strategy help WLAN support the IP packet transmission in user plane and RRC signaling transmission in control plane in LTE, and support both mobility management and session management function of non-access-stratum (NAS) protocol in LTE, which introduce the user location real-time management and LTE intra handover mechanism into WLAN, solving the problems of location management and data loss in heterogeneous handover. This method has the advantages of good compatibility with the LTE standard and least. influence on handover procedure. This paper introduces LTE-WLAN heterogeneous handover mechanism, including the handover procedure, lossless handover process, service QoS guarantee, and user location real-time management. Finally, a simulation via OPNET is presented. Simulation assessment shows the handoff latency meet the LTE standard in user planecan performance requirements and improvement in the users service QoS, which verify the introduced LTE-WLAN heterogeneous handover mechanism is feasible.