Abstract
The LTE (Long Term Evolution) technologies definedby 3GPP is the last step toward the 4th generation (4G) ofradio technologies designed to increase the capacity and speed ofmobile telephone networks. Mobility management for supportingseamless handover is the key issue for the next generationwireless communication networks. The evolved packet core (EPC)standard adopts the proxy mobile IPv6 protocol to provide themobility mechanisms. However, the PMIPv6 still suffers the highhandoff delay and the large packet lost. Our protocol providesa new protocol to reduce handoff delay and packet lost withthe assistance of relay nodes over LTE networks. In this paper,we consider the security issue when selecting relay nodes duringhandoff procedure. During the relay node discovery, we extendthe access network discovery and selection function (ANDSF)in 3GPP specifications to help mobile station or UE to obtainthe information of relay nodes. With the aid of the relay nodes,the mobile station or UE performs the pre-handover procedure,including the security operation and the proxy binding updateto significantly reduce the handover latency and packet loss. Thesimulation results illustrate that our proposed protocol actuallyachieves the performance improvements in the handoff delay timeand the packet loss rate.
Index Terms—LTE, PMIPv6, Handover, Relay, Security
I. INTRODUCTION
With the rapid growth of personal mobile communications,a mobile device with the user equipment (UE) connected tothe Internet for IP-based multimedia service is significantlyincreased. The LTE (Long Term Evolution) technologies definedby 3GPP is the last step toward the 4th generation(4G) of radio technologies designed to increase the capacityand speed of mobile telephone networks. The core network(CN) part of the evolution of the LTE system is classifiedinto the system architecture evolution (SAE) and the radioaccess network (RAN). The main objective of RAN part isto increase the system capacity, the transmission coverage,the throughput, and reduce the handoff latency. The LTEsystem is the IP based architecture, in which all radio controlfunctions, such as handover control and admission control, areenforcement in eNB. LTE system not need the central controlentity. User plane follows the same radio page link standards, suchas RLC/MAC in eNB.When a mobile user is roaming between different basestations, called as eNodeB (eNB), of LTE networks, UE needsto perform the handover protocol to keep the data connections.Traditional handover protocol suffers from high handoverlatency and large packet loss. Our main objective is to developa new handoff protocol to reduce the handover latency andimprove the packet loss rate.In this paper, we propose a secure relay-assisted handover,called RN PMIPv6, protocol for proxy MIPv6 in 3GPP LTEnetworks. The proxy MIPv6 protocol [8] still suffers fromthe high handoff delay and the large packet lost. Our protocolprovides a new protocol to reduce handoff delay andpacket lost with the assistance of relay nodes over LTEnetworks. The basic idea of the relay node performing the prehandoverprocedure is already developed in [2][3] for IEEE802.11 networks and IEEE 802.16e systems, respectively. Thedesign differences of these protocols are given in Table I.Unfortunately, none of them have considered the securityissue. In this paper, we specifically consider the security issuewhen selecting relay nodes during handoff. During the relaynode discovery, we extend the access network discovery andselection function (ANDSF) in 3GPP specifications to helpmobile station or UE to obtain the information of relay nodes.With the aid of the relay nodes, the mobile station or UEperforms the pre-handover procedure, including the securityoperation and the proxy binding update to significantly reducethe handover latency and packet loss. The simulation resultsillustrate that our proposed protocol actually achieves theperformance improvements in the handoff delay time and thepacket loss rate.The rest of this paper is organized as follows. SectionII describes the system architecture and basic ideas. Theproposed protocol is presented in section
III. Performanceevaluation is discussed in section IV. Section V finally givesa conclusion.
II. PRELIMINARY
A. Network architecture
Our approach is developed in the 3GPP LTE networks, andthe network architecture is given in Fig. 1. In the investigation,we adopt the proxy mobile IPv6 protocol as the mobilitymanagement of LTE system. When the UE received very weaksignals from current eNB and not reach to the coverage of thenext eNB, the UE tries to find a different UE, called as RN(relay node) defined below, located in coverage of the nexteNB. The RN performs the pre-handoff procedure.


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