InterRAT_HandOver-Kyungmin Kim

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<p>Voice Call Handover Scheme between 3G LTE and 3G CS Network</p> <p>Kyungmin Kim</p> <p>The Graduate School Yonsei University Department of Electrical and Electronic Engineering</p> <p>Voice Call Handover Scheme between 3G LTE and 3G CS Network</p> <p>A Masters Thesis Submitted to the Department of Electrical and Electronic Engineering and the Graduate School of Yonsei University in partial fulfillment of the requirements for the degree of Master of science</p> <p>Kyungmin KimDecember 2007</p> <p>This certifies that the masters thesis of Kyungmin Kim is approved.</p> <p>___________________________ Thesis Supervisor: [Jaiyong Lee]</p> <p>___________________________ [Seong-Lyun Kim]</p> <p>___________________________ [Jang-Won Lee]</p> <p>The Graduate School Yonsei University December 2007</p> <p>List of ContentsList of Contents ......................................................................................................... i List of Figures......................................................................................................... iii List of Tables ........................................................................................................... v Abbreviation........................................................................................................... vi Abstract ............................................................................................................... viii Chapter 1 Introduction............................................................................................... 1 Chapter 2 Overview of Existing Approaches for SRSC ................................................... 3 2.1 Combinational approach ................................................................................ 3 2.2 Call Re-establish Approach ............................................................................ 5 2.2.1 3GPP R7 VCC Review......................................................................... 5 2.2.2 Call Re-establishment Approach ............................................................ 8 2.3 Gateway Approach...................................................................................... 11 Chapter 3 FW_MME Scheme Description .................................................................. 14 3.1 Motivation................................................................................................. 14 3.2 Functionality of FW_MME .......................................................................... 14 3.3 LTE to CS Handover Procedure..................................................................... 15 3.3.1 LTE Originating Call flow .................................................................. 16 3.3.2 LTE to CS Handover Procedure ........................................................... 18 3.4 CS to LTE Handover Procedure..................................................................... 19 3.4.1 CS Originating Call flow .................................................................... 20 3.4.2 CS to LTE Handover Procedure ........................................................... 21 Chapter 4 Analysis and Evaluation............................................................................. 25 4.1 Models for Mathematical Analysis................................................................. 25 4.1.1 Radio Link Delay .............................................................................. 25</p> <p>i</p> <p>4.1.2 Network Node Queueing Delay ........................................................... 26 4.1.3 Internet and Remote Network Delay ..................................................... 28 4.2 Mathematical Analysis of Service Interruption Time ......................................... 29 4.2.1 Analytic Expressions for Partial Procedures ........................................... 29 4.2.2 Analytic Expressions for Service Interruption time .................................. 31 4.3 Numerical Result ........................................................................................ 35 4.3.1 Service Interruption Time Comparison .................................................. 35 4.3.2 Service Interruption Time and Error Rate of Air...................................... 37 Chapter 5 Conclusion .............................................................................................. 42 References............................................................................................................. 44</p> <p>ii</p> <p>List of FiguresFigure 2.1 Combination of existing handover schemes .................................................... 3 Figure 2.2 Coverage assumption of combinational approach ............................................ 4 Figure 2.3 Conceptual operation of R7 VCC ................................................................. 5 Figure 2.4 R7 VCC handover signal flow: from PS to CS ................................................ 6 Figure 2.5 R7 VCC handover fignal flow: from CS to PS ................................................ 7 Figure 2.6 Conceptual operation of call re-establishment ................................................. 8 Figure 2.8 Call re-establishment handover signal flow: form CS to LTE........................... 10 Figure 2.9 Conceptual operation of gateway approach................................................... 11 Figure 2.10 Gateway approach handover signal flow: from LTE to CS............................. 12 Figure 2.11 Gateway approach handover signal flow: from CS to LTE............................. 13 Figure 3.1 Functionalities of FW_MME ..................................................................... 14 Figure 3.2 LTE originating call diagram ..................................................................... 16 Figure 3.3 LTE originating call flow .......................................................................... 17 Figure 3.4 LTE to CS handover signal flow ................................................................. 18 Figure 3.5 CS originating call diagram ....................................................................... 20 Figure 3.6 LTE originating call flow .......................................................................... 21 Figure 3.7 CS to LTE handover signal flow ................................................................. 22 Figure 4.1 M/M/1 queueing model of network node ..................................................... 26 Table 4.1 Arrival rate of each network node................................................................. 27 Table 4.2 Service rate of each network node ................................................................ 27 Figure 4.2 M/G/1 queueing model of network node ...................................................... 28 Figure 4.3 CS attachment signal flow ......................................................................... 29 Figure 4.4 PDP context activation.............................................................................. 30 Figure 4.5 IMS registration....................................................................................... 31</p> <p>iii</p> <p>Figure 4.6 Signal flow of call re-establishment: LTE to CS handover............................... 32 Figure 4.7 Signal flow of call re-establishment: CS to LTE handover............................... 33 Figure 4.7 Signal flow of gateway approach: LTE to CS handover .................................. 34 Figure 4.8 Signal flow of gateway approach: CS to LTE handover .................................. 34 Figure 4.9 Service interruption time for LTE to CS handover ......................................... 35 Figure 4.10 Service interruption time for CS to LTE handover........................................ 36 Figure 4.11 LTE to CS service interruption time vs. frame error rate................................ 37 Figure 4.12 CS to LTE service interruption time vs. frame error rate................................ 38 Figure 4.13 Service interruption time vs. propagation delay of air ................................... 39 Figure 4.14 Service interruption time vs. queueing delay variation of network node ........... 40 Figure 4.15 Service interruption time vs. queueing delay variation of network node: .......... 40</p> <p>iv</p> <p>List of TablesTable 4.1 Arrival rate of each network node................................................................. 27 Table 4.2 Service rate of each network node.. ....................................................... 27</p> <p>v</p> <p>Abbreviation3G 3G LTE 3GPP BS BSS CS CSCF ENB I-CSCF IMS IMT IMPI IMPU IMSI IP MGCF MGW MIH MME MSC P-CSCF PDP PS R7 3rd Generation 3rd Generation Long Term Evolution 3rd Generation Partnership Project Base Station (or Node B) Base Station Subsystem Circuit Switched Call Session Control Function Enhanced Node B (or BS) Interrogating-CSCF IP Multimedia Subsystem International Mobile Telecommunication IP Multimedia Private Identity IP Multimedia Public User identity International Mobile Subscriber Identity Internet Protocol Media Gateway Control Function Media GateWay Media Independent Handover Mobility Management Entity Mobile service Switching Center Proxy-CSCF Packet Data Protocol Packet Switched Release 7</p> <p>vi</p> <p>RLP RRC SAE S-CSCF SIP SRSC TMSI UA UE UMTS VCC VoIP</p> <p>Radio Link Protocol Radio Resource Control System Architecture Evolution Serving-CSCF Session Initiation Protocol Single Radio Service Continuity Temporal IMSI User Agent User Equipment Universal Mobile Telecommunication System Voice Call Continuity Voice over IP</p> <p>vii</p> <p>AbstractVoice Call Handover Scheme between 3G LTE and 3G CS NetworkKyungmin Kim Dept. of Electrical and Electronic Engineering The Graduate School Yonsei University Convergence of different network technologies is major trend of today's network evolution. Therefore many network technologies coexist and each technology has different coverage and different characteristic. In this environment, mobile node can move between heterogeneous network technologies, and it can disrupt the continuity of ongoing session. Hence, the seamless handover scheme between different network technologies is necessarily required that is called as inter-system handover. Inter-system handover has several difficulties that different characteristic of network systems, network inter-working problem, and radio resource limitation. Voice call handover between 3G LTE and 3G CS network is a kind of inter-system handover that todays hot issue of 3GPP working group. To make a handover scheme between 3G LTE and 3G CS, there are two critical problems that lack of interface between two network systems and radio resource limitation to single radio. Moreover the characteristic of voice call is very sensitive to service interruption time. Accordingly a special low latency handover scheme is required to provide seamless service. In this paper, the performances of existing inter-system handover schemes are evaluated. viii</p> <p>And an enhanced voice call handover scheme between 3G LTE and 3G CS system is proposed. Also service interruption times of each handover scheme are analyzed. The result of the analysis shows that the proposed scheme has the smallest service interruption time and only proposed scheme can satisfy the strict requirement of service interruption time of voice call handover that less than 300 ms. And finally we conclude that we can provide seamless voice call handover using proposed scheme.</p> <p>.Key words : Voice-Call, Handover, 3G LTE, ,3G CS, Inter-system,</p> <p>ix</p> <p>Chapter 1 IntroductionAll IP convergence and inter-working between different network technologies are hot issues of todays network evolution. Since each network technology has different characteristic, to couple different network technologies is difficult to effect. And many legacy telecommunication network systems do not support IP service, it is another problem of network evolution to all IP convergence. 3G LTE system is one of a leading candidate for next generation network system. It assumes IP based PS only network and voice call should be served by VoIP. Since 3G LTE system is expected to have hot spot coverage, 3G system will exists as an infrastructure system of 3G LTE system. Accordingly, voice call handover between 3G LTE system and 3G CS system is necessarily required to provide seamless service. But complete handover scheme for 3G LTE and 3G CS system does not exist. To enable handover between 3G LTE and 3G CS, there are two critical problems. First problem is the absence of network interface between two network systems. For legacy intra-system handover, network level backward handover can be executed by the inter-working of network entities that exist in same network system. But for inter-system handover, network level backward handover is hard to be achieved due to the absence of network interface. Hence larger handover latency is prospected compare to intra-system handover. The second problem is the limitation of radio resource. For 3G LTE and 3G CS system, we can't use dual radio simultaneously because of spectrum interference and battery consumption issues. For this reason, the voice call handover scenario between 3G LTE and 3G CS system is called as SRSC (Single Radio Service Continuity). Therefore, for SRSC scenario, we can't use existing 'make before break' schemes like 3GPP VCC or IEEE 802.21 MIH that based on dual radio capability. Thus we cannot but use 'break before make scheme that causes larger service interruption time.</p> <p>1</p> <p>There are some approaches to solve the problem of SRSC. They are categorized as three categories that combinational approach, call re-establishment approach, and gateway approach. First combinational approach has many problems that inefficient and indirect handover process, network coverage problem, and large service interruption time. Second call reestablishment approach provides direct and provides simpler handover process compare to the combinational approach. But it also has large service interruption time problem. The last gateway approach has the smallest service interruption time among the tree approaches. But still the service interruption time is unacceptable because to satisfy the strict requirement of voice call and detailed session immigration procedure does not defined. Also authentication and security problems should be concerned to be a complete solution. Therefore a new advanced handover scheme that can satisfy the requirement for voice call is necessarily required. The remainder of this paper is organized as follows: Section 2, we study about the three approaches solving SRSC problems. In section 3, the proposed FW_MME scheme is presented and also detailed handover procedure is explained. In section 4, the performance analysis of schemes for SRSC is done. And from the analysis, we compare the performance and confirm the superiority of proposed scheme. And finally at section 6, we conclude this paper.</p> <p>2</p> <p>Chapter 2 Overview of Existing Approaches for SRSCAppro...</p>