Seamless Services in Vertical Handover 4G Forum 건국대학교새천년기념관 2007. 11. 21 Jae-Hyun Kim (jkim@ajou.ac.kr) School of Electrical Engineering Ajou University, Korea Homepage: http://ajou.ac.kr/~jkim
목차 핸드오버기술개요 2계층이동성보장기술 3계층이동성보장기술 4계층이동성보장기술수직핸드오버기술결론 2
핸드오버기술개요 국내이동통신서비스현황 이동통신망상호공존요인 핸드오버정의 핸드오버기술분류 핸드오버평가척도 계층별핸드오버기술 3
핸드오버기술개요 국내이동통신서비스현황이동통신망상호공존요인핸드오버정의핸드오버기술분류핸드오버평가척도계층별핸드오버기술 4
용어정의 이동단말 MN (Mobile Node), MS (Mobile Station), UT (User Terminal) 기지국또는접속점 AP (Access Point), BS (Base Station) PoA (Point of Attachment) CoA (Care-of-Address) Router RCoA (Regional Care-of-Address) LCoA (On-link Care-of-Address) PAR (Previous Access Router) NAR (New Access Router) MAP (Mobility Anchor Point) MAG (Mobile Access Gateway) LMA (Local Mobility Anchor) 5
국내이동통신서비스현황 2 세대 CDMA 고속의이동속도에서음성, 간단한데이터서비스제공 3 세대 WCDMA 영상통화와같은대용량서비스제공가능 WLAN 고속의데이터를낮은서비스비용으로제공 WiBro 이동환경에서 WLAN 에준하는전송속도제공 km/h 250 Mobility 100 2G cellular 3G cellular 3G evolution & IEEE 802.16m evolution IEEE 802.16e 3 IEEE802.11n 2G cellular Next Generation WLAN 1 10 100 Transmission Rate 1000 Mbps - CDMA : Code Division Multiple Access - WCDMA : Wideband CDMA - WLAN : Wireless Local Area Network 6
이동통신망상호공존요인 이동통신망상호공존요인 경제적요인기존통신망의재활용을통한망설치비용절감서비스특성에따른망선택을통한서비스비용절감 기술적요인 단일통신망으로사용자의요구를만족시키기어려움 높은전송속도, QoS, 고속의이동속도 통신망의변경에따른서비스의단절을줄이기위한이동성보장기술필요 7
핸드오버의정의 IETF (Internet Engineering Task Force) 서비스를받고있는단말이 PoA 를변경하거나변경을시도하는과정 [1] WINNER (Wireless World Initiative New Radio) 접속망에서정의된베어러 (bearer) 서비스를제공하기위하여사용중인무선송수신기 / 시스템모드 / 무선시스템을변경하는과정 [2] IEEE 802.21 MIH(Media Independent Handover) 링크스위치이벤트의발생시 MN 에서트래픽플로우의특성을유지하기위한과정 [3] [1] J. Maner, and M. Kojo, Mobility related Terminology, RFC3753, Jun., 2004 [2] WINNER, D4.1: Identification and definition of cooperation schemes between RANs, internal deliverable, IST-2003-507581 WINNER, Jun., 2004 [3] IEEE P802.21 /D01.00, IEEE P802.21/D01.00 Draft IEEE Standard for Local and Metropolitan Area Networks: Media Independent Handover Services, Mar., 2006 8
핸드오버기술분류 Handover classification Network types involved Frequencies engaged Number of connection involved Horizontal handover Vertical handover Intrafrequency Interfrequency Hard Handover Soft Handover Softer Handover Handover In same Network technology Handover In different network technology Handover between access point operating on same frequency Handover between access point operating on different frequency Mobile node maintain only one connection Mobile node can maintain more than two connection Mobile node switches connections In same access point Triggering object User control allowance Necessity of handover Initiation Decision Proactive handover Passive handover Obligatory handover Voluntary handover Mobile initiated BS initiated Mobile decision BS decision User sets Preference of handover decision User cannot control handover decision Handover must be executed in order to avoid disconnect Handover may be executed to improve the quality of service [4]N. Nasser et al, Handoffs in Fourth Generation Heterogeneous Networks IEEE Commun. Mag., vol. 44, no. 10, Oct. 2006, pp. 96-103. 9
핸드오버평가척도 척도 정의 필요기술 신뢰성 (Reliable) 핸드오버이후서비스의품질이일정하게유지되는정도 핸드오버를수행할단말에게제공할수있는서비스품질정보를기반한핸드오버결정기술 연결성 (Seamless) 핸드오버를수행하는동안서비스의품질이일정하게유지되는정도 핸드오버의이전에이동단말에관한정보를상호교환하는기술 간섭회피율 (Interference Prevention) 부하제어 (Load Balancing) 핸드오버수행단말의무선채널과동일또는인접채널을사용하는단말로인한간섭에대한회피정도 기지국또는접속점의가용한자원을균일하게유지하기위한제어 송신전력을제어하는전력제어기술 간섭회피기술 기지국간부하제어기술 셀부하정보를기반으로하는핸드오버결정기술 핸드오버 수행횟수 한번의품질저하극복및서비스요구를충족시키지위해시행되는핸드오버횟수 상대적임계값을이용한핸드오버결정기술 [4]N. Nasser et al, Handoffs in Fourth Generation Heterogeneous Networks IEEE Commun. Mag., vol. 44, no. 10, Oct. 2006, pp. 96-103. 10
계층별핸드오버기능 Layer 4 or upper Layer 3 Layer 2.5 Layer 2 11
2계층이동성보장기술 핸드오버관련정보측정기술 (Scanning) 트리거 (Initiation) 핸드오버결정 (Decision) 핸드오버수행 (Execution) 상향링크정보를이용한핸드오버 12
2계층이동성보장기술과정 Trigger threshol d Hysteresis Serving cell Target cell Measurement Trigger Decision & Execution 13
핸드오버관련정보측정기술 현재통신조건에적합한무선통신망을찾기위한정보의획득방법 측정정보물리계층측정정보 : 신호세기 (RSSI), 신호대잡음및간섭비율 (SNR, SINR) 상위계층측정정보 : 셀부하, 사용자선호정보, QoS 제공정도측정대상 Preamble signal, feedback report, pilot channel WINNER 프로젝트의측정요구사항 Signal strength, Transmitted power, Quality, Cell load - RSSI : Received Signal Strength Indicator - SNR : Signal to Noise Ratio -SINR : Signal to Interference plus Noise Ratio 14
핸드오버관련정보측정기술 : Location-based Vertical Handover 이종망간핸드오버를용이하게하기위하여 WINNER 프로젝트에서제안 [5] 1. UT 가주기적으로채널정보전송 2. BS 또는 AP 는전송된채널정보와위치정보를 HIS(Hybrid Information System) DB 로저장 3. 수직핸드오버의필요시 BS 또는 AP 에채널정보요청 4. BS 또는 AP 는 UT 의예상채널정보를획득하기위하여 HIS 에위치정보전송 5. HIS 는전송된위치정보를바탕으로예상채널정보를 UT 에전송 [5] WINNER, D4.3: Identification and definition of cooperation schemes between RANs final deliverable IST-2003-507581 WINNER, Jun., 2005 15
핸드오버관련정보측정기술 : IEEE 802.16e 의 Scanning 핸드오버에적합한인접기지국을결정하기위하여 serving BS 와 neighbor BS 의신호측정 MS BS #1 (Serving) BS #2 (Target) BS #3 (Target) Scanning procedure Scanning Interval duration = N frames Scanning Interval duration = N frames Scanning request by MS M frames Synchronize with BS #2, measure metrics Synchronize with BS #3, measure metrics Non-scanning interleaving Interval (P frames) Synchronize with BS #2, measure metrics Synchronize with BS #3, measure metrics MOB_NBR-ADV (N_NEIGHBORS =2) MOB_SCN-REQ (Scan duration = N frames, Interleaving interval = P frames, Iteration= 2 times) MOB_SCN-RSP (start frame = M frames, duration = N frames) Data Traffic (if any) [6] IEEE Std 802.16e-2005, Part 16: Air Interface for Fixed and Mobile Broad-band Wireless Access Systems, Feb. 2006 16
핸드오버관련정보측정기술 : IEEE 802.16e 의 Scanning Scanning 동안예상기지국과정보교환 Ranging parameter(power offset, CDMA code, etc.) 과 Basic service capability 정보획득 Association level Level 0: Scan / Association without coordination Contention based ranging Level 1: Association with coordination Unicast ranging 인접기지국에서유효한 CDMA ranging code 와 transmission opportunity(rendezvous time) 전송 Level 2: Network assisted association reporting Multicast ranging 인접기지국에게유효한 CDMA ranging code 코드만할당받음 Ranging 구간은 serving BS 에게부여받음 17
핸드오버관련정보측정기술 : IEEE 802.16e 의 Association MS BS #1 (Serving) BS #2 (Target) BS #3 (Target) Scanning with Association procedure Scanning request by MS MOB_NBR-ADV (N_NEIGHBORS =2) MOB_SCN-REQ (duration = N frames, Association level) MOB_SCN-RSP (start frame = M frames, duration = N frames, Association parameter) M frames Synchronize with BS #2, measure metrics Scanning Interval duration = N frames RNG-REQ (Association : Initial ranging) RNG-RSP (Ranging parameter, service level) Synchronize with BS #3, measure metrics RNG-REQ (Association : Initial ranging) RNG-RSP (Ranging parameter, service level) [6] IEEE Std 802.16e-2005, Part 16: Air Interface for Fixed and Mobile Broad-band Wireless Access Systems, Feb. 2006 18
트리거 (Trigger) 측정된정보를기반으로핸드오버알고리즘에특정한행동을취하도록명령하는것 측정된링크품질이임계값이하일경우 스케닝, 핸드오버시작 WINNER 프로젝트의 L2 트리거 물리적인정보를기반으로한트리거신호세기, 간섭수준, BER/PER(Packet Error Rate) 서비스측면에서알고리즘에의한트리거 QoS violation, CAC&CF(Connection Admission Control & Connection Forwarding), 위치, 이동속도, 사전정보, 서비스가능유무 19
트리거 (Trigger): IEEE 802.16e 의핸드오버초기화과정 MS BS #1 (Serving) BS #2 (Target) BS #3 (Target) Handover initiation by MS request MOB_MSHO_REQ (Recommended BS = BS#2, BS#3) (Neighbor BS#2 : CINR = v1) (Neighbor BS#3 : CINR = v2) MOB_MSHO_RSP (BS_ID = BS#3) HO-pre-notification (MS identifier, connection parameters, capabilities, required BW and QoS ) HO-pre-notification (MS identifier, connection parameters, capabilities, required BW and QoS ) HO-pre-notification-response (Ack, lower QoS class) HO-pre-notification-response (Ack, lower QoS class) HO-confirm Handover initiation by BS request MOB_BSHO_REQ (Recommended BS=BS#2, BS#3) (BS#2 service level prediction =2) (BS#3 service level prediction =2) (Resource Remain Type = MS resource retain) HO-pre-notification (MS identifier, connection parameters, capabilities, required BW and QoS ) HO-pre-notification (MS identifier, connection parameters, capabilities, required BW and QoS ) HO-pre-notification-response (Ack, lower QoS class) HO-pre-notification-response (Ack, lower QoS class) [6] IEEE Std 802.16e-2005, Part 16: Air Interface for Fixed and Mobile Broad-band Wireless Access Systems, Feb. 2006 20
핸드오버결정 (Decision) 핸드오버결정요인 수평적핸드오버 신호품질및망내자원상황 수직적핸드오버 망내부하, 서비스가격, 지원가능한통신속도, 보안, 이동속도및전력소모 WINNER 프로젝트의핸드오버결정 Handover initiation Signal strength, cell load, user preference, etc. Handover decision Signal strength, cell load, user preference, etc. IEEE 802.16e MS initiated & decision, BS initiated & BS decision Signal strength, cell load, QoS level 21
[6] IEEE Std 802.16e-2005, Part 16: Air Interface for Fixed and Mobile Broad-band Wireless Access Systems, Feb. 2006 핸드오버결정 : IEEE 802.16e 의핸드오버결정 MS BS #1 (Serving) BS #2 (Target) BS #3 (Target) MOB_MSHO_REQ (Recommended BS = BS#2, BS#3) (Neighbor BS#2 : CINR = v1) (Neighbor BS#3 : CINR = v2) MOB_MSHO_RSP (BS_ID = BS#3) HO-pre-notification (MS identifier, connection parameters, capabilities, required BW and QoS ) HO-pre-notification (MS identifier, connection parameters, capabilities, required BW and QoS ) HO-pre-notification-response (Ack, lower QoS class) HO-pre-notification-response (Ack, lower QoS class) HO-confirm Decision to execute handover MOB_HO_Indicaiton (Time=L frames) Release of MS Decision to cancel handover MOB_HO_Indicaiton Downlink traffic 22
핸드오버수행 Serving BS 와의연결을종료하고 target BS 와의무선링크를재설정하는과정 Seamless handover 끊어짐없는핸드오버를제공하기위해서는서비스별로정의된지연한계이내에핸드오버수행을완료해야함 Application Conversational voice Video phone Telemetry Interactive games Telnet Voice messaging Video phone One-way delay <150 msec preferred, <400 msec limit <150 msec preferred, <400 msec limit < 250 msec < 250 msec < 250 msec < 1 sec for playback, < 2 sec for record < 4 sec /page 23
핸드오버수행 : IEEE 802.16e 의핸드오버수행 핸드오버수행절차 Down link synchronization 하향채널동기, preamble detection DL-MAP/ UL-MAP detection 하향링크주파수조정 Ranging CID(Connection ID) 할당, 상향링크 frequency/uplink power/time 조정 Ranging 방안 물리계층에따라달라짐 Time slot 으로구분 (OFDM, SC(Single Carrier), SCa PHY) Time slot 과 CDMA code 로구분 (OFDMA PHY) 접근방안 경쟁기반접근방안 비경쟁기반접근방안 24
핸드오버수행 : IEEE 802.16e 의핸드오버수행 MS BS #2 (Target) OFDM PHY Non-contention based ranging Using Fast ranging IE() when scanning has done with association Fast Ranging_IE(UL_MAP) RNG-REQ (MS MAC address, Serving BS_ID, Raging Purpose Indication, HMAC/CMAC) RNG-RSP (MS MAC address, Basic CID, Primary CID, HO Process Optimization, CID Update, CMAC) Downlink traffic UL-MAP IE() BR Header Complete Initial Network Entry (after handover) OFDMA PHY Contention based ranging Without association CDMA Code for Handover Ranging RNG-RSP (Raging status = Success) UL_MAP : CDMA Allocation IE() RNG-REQ (MS MAC address, Serving BS_ID, Raging Purpose Indication, HMAC/CMAC) RNG-RSP (MS MAC address, Basic CID, Primary CID, HO Process Optimization, CID Update, CMAC) Downlink traffic CDMA Code for BR UL-MAP IE() : CDMA Allocation IE() BR Header Complete Initial Network Entry (after handover) [6] IEEE Std 802.16e-2005, Part 16: Air Interface for Fixed and Mobile Broad-band Wireless Access Systems, Feb. 2006 25
IEEE 802.16e 의 2계층핸드오버과정 Initiated by MS request MS BS #1 (Serving) BS #2 (Target) BS #3 (Target) Initiation MOB_MSHO_REQ (Recommended BS = BS#2, BS#3) (Neighbor BS#2 : CINR = v1) (Neighbor BS#3 : CINR = v2) HO-pre-notification (MS identifier, connection parameters, capabilities, required BW and QoS ) HO-pre-notification (MS identifier, connection parameters, capabilities, required BW and QoS ) HO-pre-notification-response (Ack, lower QoS class) HO-pre-notification-response (Ack, lower QoS class) Decision Execution MOB_MSHO_RSP (BS_ID = BS#3) MOB_HO_Indicaiton (Time=L frames) Release of MS HO-confirm Fast Rainging_IE(UL_MAP) RNG-REQ RNG-RSP Complete Initial Network Entry (after handover) [6] IEEE Std 802.16e-2005, Part 16: Air Interface for Fixed and Mobile Broad-band Wireless Access Systems, Feb. 2006 26
상향링크정보를이용한핸드오버 연구배경 IEEE 802.16e 와같은 TDD OFDMA 에서는셀내의 MS 의위치와분포에따라 Uplink 와 Downlink 의채널품질이다를수있음 주기적인 Scanning 으로인한통신두절이있음 특징주기적인 Scanning 구간대신핸드오버요청시에만주변기지국의신호를측정 핸드오버결정요인으로 Uplink 와 Downlink 를모두고려
[7]S. H. Cho et al, Hard handoff scheme exploiting using uplink and downlink signal in IEEE 802.16e system, VTC 2006 Fall 상향링크정보를이용한핸드오버과정 MS BS#1 (Serving) BS#2 (Target) BS#3 (Target) Th1 : Uplink 를고려한핸드오버결정임계값 Th2 :AMC 유저를위한핸드오버임계값 Th3 : 상향링크를고려한핸드오버대상기지국결정임계값 (UL hysteresi 사용 ) Th4 : 통신을위한최소 Downlink 신호품질임계값 Th5 : 하향링크를고려한핸드오버대상기지국결정임계값 (UL hysteresi 사용 ) Th6 : 통신을위한최소 Upnlink 신호품질임계값 Downlink 신호품질측정 Uplink 신호품질측정 (user ID, resource allocation informatio) Downlink 신호품질측정결고보고 Uplink 신호품질측정결과보고 Downlink 와 Uplink 를고려한핸드오버결정 P P UL _ target PUL _ serving > TH 3 & PDL_target > TH 4 DL _ target PDL_ serving > TH 5 & PUL_target > TH 6
2.5 계층이동성보장기술 IEEE 802.21 Media Independent Handover (MIH) 29
IEEE 802.21 MIH 최적화된핸드오버를수행하기위하여필요한망에관련된정보와무선링크의정보의제공 2 계층이동성관리기술의정보와상위계층이동성관리기술의연동 MIH 제공서비스 Event services Command services Information services < MIH 프로토콜스택 > [8]IEEE 802.21/D03.00, Draft IEEE Standard for Local and Metropolitan Area Networks: Media Independent Handover Services, December 2006 30
IEEE 802.21 MIH: Multiple Access Network Reference Model MIH provides convergence of link-layer state information from multiple heterogeneous access technologies Supported by existing SAP in IEEE 802.x Not exist SAP for MIH in 3GPP/3GPP2 MIH defines MIH_3GLINK_SAP to use MIH for 3GPP/3GPP2 - LSAP : Link Service Access Point - LLC : Link Layer Control -SAP : Service Access Point -MLME : MAC Layer Management Entity - PLME : Physical Layer Management Entity - CS : Convergence Sublayer 31
IEEE 802.21 MIH: MIH Services Media independent event services 하위계층의상태변화를상위계층에알리는역할수행이벤트생성위치에따른분류 Remote event : 다른망요소에서생성된이벤트 Local event : 동일한망요소에서생성된이벤트이벤트인식위치에따른분류 Link event : PHY, MAC MIH MIH event : MIH L3+ 이벤트내용에따른분류 MAC/PHY 상태변화이벤트 MAC 또는 PHY 계층의상태변화링크파라미터이벤트링크계층파라미터의변화예측이벤트과거와현재의조건을기반으로링크의변화예측정보알림링크동기이벤트링크계층동작에관한정보알림링크전송이벤트링크계층에서상위계층 PDU 의전송상태알림 32
IEEE 802.21 MIH: MIH Services Media independent command service 링크의상태를결정하고다중모드단말을제어명령생성위치에따른분류 Remote command : 다른망요소에서생성된명령 Local command : 동일한망요소에서생성된명령명령인식위치에따른분류 MIH event : L3+ MIH Link event : MIH PHY, MAC Media independent information service 핸드오버에필요한정보를획득하기위하여사용됨 Neighbor map, link layer information, availability of service Type 0x0 : Core MIH specific IEs 0x2 : Vender specific IEs 0x3 : Working group specific IEs 33
3계층이동성보장기술 Fast Mobile IPv6 (FMIPv6) Hierarchical MIPv6 (HMIPv6) Proxy Mobile IPv6 (PMIPv6) 34
Fast Mobile IPv6 (FMIPv6) 설계목적 경로최적화를통한망효율성향상 핸드오버에의한패킷손실감소 Binding Update 에의한핸드오버지연감소 특징 new PoA 의발견시 old PoA 를통한 binding update L3 핸드오버이전에 old PoA 에서미전송된패킷을터널링시킴 패킷손실감소 핸드오버동안터널링된패킷수신 핸드오버지연감소 CoA 관리를 CN(Corresponding Node) 이수행 HA(Home Agent) 를경유하지않음 경로최적화 MN 가현재의 AR 에 L2 연결을유지하고있는동안에 L3 핸드오버수행 CoA 등 MN 에대한정보를미리공유 AR 정보교환프로토콜이필요 [9] R. Koodli, Fast Handovers for Mobile IPv6, RFC4068, Jul.,2005 35
Fast Mobile IPv6 (FMIPv6): 동작절차 CN 4. HI PAR 5. HAck NAR 9. BU 1. RtSolPr 8. FNA 3. FBU 6. FBAck AP 2. PrRtAdv AP MN 0. Movement 7. Movement MN MN -RtSolPr : Router Solicitation for Proxy Advertisement -PrRtAdv : Proxy Router Advertisement -FBU : Fast Binding Update - HI : Handover Initiate -Hack : Handover Acknowledge -FBAck : Fast Binding Acknowledgment -FNA : Fast Neighbor Advertisement -BU : Binding Update 36
Hierarchical MIPv6 (HMIPv6) 설계목적 MIPv6 에서잦은핸드오버시 MN 과 HA, CN 사이에발생하는 Binding update 의부하를줄이기위함 특징망을계층구조로관리 상위 MAP 의변경에따른 RCoA 의변경필요시에만 HA 와 CN 에게 Binding update MAP(Mobility Anchor Point) Local HA(Home Agent) 의역할 RCoA (Regional Care-of-Address) 최상위층의 MAP 에따라결정되며 HA 에등록되는 CoA LCoA(On-link Care-of-Address) 같은 MAP 의네트워크안에서구별가능한 CoA [10] H. Soliman, C. Castelluccia, K. El Malki and L. Bellier, Hierarchical Mobile IPv6 Mobility Management (HMIPv6), RFC 4140, August 2005 37
Hierarchical MIPv6 (HMIPv6): 동작절차 CN HA MAP1 6. Binding Update (RCoA1 RCoA2) (LCoA2 LCoA3) 3. Binding Update Acknowledg MAP2 7. Binding Update Acknowledg AR1 AR2 AR3 AR4 Care- of-address (RCoA1) (LCoA1 ) MN 2. Binding Update (RCoA1 RCoA1) (LCoA1 LCoA2) 1. Router Advertisements 0. Movement 4. Movement Care- of-address (RCoA1) (LCoA2 ) 5. Router Advertisements Care- of-address (RCoA2) (LCoA3 ) 38
Proxy Mobile IPv6 (PMIPv6) 설계목적 IPv6 지원망에서단말이이동관련시그날에관련하지않고이동성을제공하기위함 특징네트워크기반 Mobile IP IP mobility 에의한단말의변화없음 Tunneling overhead 감소 MN 과 HA,CN 간의 Binding Update overhead 감소 Mobile IPv6 의재사용 실제구현및설치에용의함 위치정보보안강화 MN-HoA(Home-of-Address) 를유지하여위치추적이쉽지않음 [11]S. Gundavelli, K. Leung, V. Devarapalli, K. Chowdhury and B. patil, Proxy Mobile IPv6, draft-ietf-netlmm-proxymip6-00.txt, April 8, 2007 39
Proxy MIPv6 (PMIPv6): 동작절차 CN Update Binding cache Entry for the MN 3. AAA Reply AAA-server LMA 5. Proxy BU 2. AAA Query 6. Proxy BU ACK MAG1 MAG2 4. Router Advertisement 1. Router Solicitation MN 0. Movement IP address configuration (MN-HoA) -Proxy BU : Proxy Binding - Proxy BU ACK : Proxy Binding Acknowledge -AAA : Authentication Authorization Accounting 40
4계층이동성보장기술 SIP Application layer handover 41
SIP(Session Initiation Protocol) IETF 에서세션 (session) 을관리하기위하여정의 응용계층프로토콜 Initiation, management, termination of sessions across packet network re-invite를사용한이동성보장기술에참여가능 SDP (Session Description Protocol) 세션에관련된보다자세한정보를관리 Session name and purpose Times the session is active Media to use Information where to send and receive media Contact information <reference> 42
SIP(Session Initiation Protocol) : Session initiation procedure 1. INVITE 5.re-INVITE 1. INVITE Location/Redirect Server 2. 302 (Moved Temporarily) Proxy Server Proxy Server Proxy Server User Agent AP AP MN MN MN 43 1. INVITE 3. ACK 4. 180(Ringing) 3. 200(OK) ACK 3. ACK 6. 180(Ringing) 200(OK) 2. 302 (Moved 6. ACK Temporarily) 3. ACK 1. INVITE 4. 180(Ringing) 200(OK) 4. 180(Ringing) 200(OK) 3. ACK 1. INVITE 5.re-INVITE 6. 180(Ringing) 200(OK) 6. ACK 5.re-INVITE
Application layer handover 핸드오버지연을최소화시키기위하여망의도움없이다중경로 / 다중세션기술을사용하여접속망을변경하는과정 배경 Coexistence 향후통신서비스는 CDMA2000, UMTS, WiBro, WLAN 등의다양한무선통신망이상호공존할것으로예상됨 Multi-interface support 하나의 MN이여러개의RAT를사용함각 RAT는독립된interface를가짐 MN은 multi-homing 기술을지원함 UMTS : Universal Mobile Telecommunication System 44
Application layer handover: Reference Architecture 1 Application program/user interface 1 Handover policy of user(cost plan, service plan) Application Transport RTP/RTCP UDP 5 SDP SIP 2 Handover Decision TCP 4 3 6 2 Information of service flows(type, format, transport protocol, IP addresses for send/receiver, port number) 3 Information about active RAT and candidate RAT 4 Sequence information for the TCP service flow Network IPv4, IPv6, MIP, HIP 5 Time stamp information for the UDP service flow Link Physical MIH WINNER UMTS WLAN Information Control UDP service flow TCP service flow 7 6 Control for the handover service flow during Inter- RAT handover 7 Handover management (Handover preparation, Handover execution RAT selection) 45
Application layer handover: Handover Decision Module Handover decision module 의기능 From SDP,SIP Service flow information Concatenated Flow Handover decision From User interface Handover policy of user Control Information Management QoS monitoring information QoS Management Service flow information User Sequence Management From MIH Available RAT information User preference RAT information Handover control (Measurement, Modem on/off, Link setup, Registration request) Handover Management Session Duplicate Request Session control (Session generation, termination) Multi session identify Flow 1 Flow 2 46
Application layer handover: Handover Decision Module 의세부기능 척도서비스품질관리서비스품질관리시퀀스관리핸드오버관리 세부기능 서비스플로우정보관리 사용자 RAT 선호도관리 RAT 관련정보관리 서비스플로우요구자원관리 서비스플로우 QoS 파라미터관리 핸드오버서비스플로우설정관리 다중경로서비스플로우결합관리 TCP 서비스플로우시퀀스관리 UDP 서비스플로우 time stamp 관리 핸드오버초기화제어 핸드오버수행접속망선택 핸드오버완료제어 역할 SIP, SDP, 서비스클래스를통한세션정보관리 사용자가입력한 RAT 선호정보관리 사용가능한 RAT 의무선정보관리 서비스플로우가요구하는 QoS 를만족시키기위하여필요한자원을관리 현재설정된서비스플로우와관련된 QoS 파라미터관리 다중경로서비스플로우설정을위한동작수행 다중경로로전송된동일한서비스플로우의인지 TCP 시퀀스정보를이용하여서비스플로우결합 UDP/RTP time stamp 정보를통한서비스플로우결합 RAT 선호도 / RAT 관련정보를고려한무선링크설정 QoS 를만족시킬수있는접속망선택 다중경로서비스플로우의해제관리 47
Application layer handover: Concept Service flow Service flow RAN2 modem up Session Request RAN 1 GW GW RAN 2 Session request Measurement Link setup MN Signal Quality for RAN 1 Measurement trigger MIH Handover magt. Handover init. trigger MIH Handover magt. Service Flow 1 Flow 2 Signal Quality for RAN 2 Handover decision trigger MIH Handover magt. 48
수직핸드오버기술 수직핸드오버정의및분류 수직핸드오버요구기술 Coupling Coupling method Radio Radio Resource Management WINNER Cooperation mechanism 49
수직핸드오버정의및분류 Vertical handover Inter-system handover between two different radio systems on different layers of the overlay structure Two type of vertical handover Downward vertical handover Handover to a cell of smaller size Upward vertical handover Handover to a cell of larger size 50
수직핸드오버요구기술 Coupling Method 이종접속망간의결합방안으로다음사항을고려표준의수정정도상호연동의끊어짐정도공통망요소의정도 Tight coupling Each network shares same core network Loosely coupling Each network has individual core network Connected by gateway 51
수직핸드오버요구기술 Radio Resource Management (RRM) 망자원을효과적으로사용하기위하여요구되는기술 Admission control : 혼잡을예방하기위한기술 Load/congestion control : 혼잡을해결하기위한기술 QoS management : 서비스품질관리기술 Combined RRM Resources are allocated centrally for all involved RATs by a single entity Ex) Common RRM, Joint RRM Concurrent RRM Resources are allocated within each RAT by a local entity in a distributed manner 52
Coupling Method Tight coupling vs. Loosely coupling 망활용성운영비용성능기술적어려움 Tight Coupling Loose Coupling Open Coupling 별도의망설치필요없음 별도의망설치필요 망운영비용이저렴 망운영비용증가 수직핸드오버성능증가 수직핸드오버성능감소 새로운망을추가하는것이어려움 새로운망의추가가용이 53
Radio Resource Management: Common RRM Proposed by UTRAN and GERAN in 3GPP Support the cooperation between UMTS and GSM/GPRS Two component (same layer) CRRM Be responsible for coordinating a certain number of RRM entities RRM Be responsible for the allocation inside one radio resource pool 54
Radio Resource Management: Joint RRM Proposed by TRUST and SCOUT Support the cooperation between HyperLan2 and UMTS Consist of the mechanism and the architecture for heterogeneous UT in B3G TRUST : Transparently Reconfigurable Ubiquitous Terminal SCOUT : Smart User-Centric Communication Environment 55
Radio Resource Management: Layered RRM Proposed by WINNER project Consider multi-technology / multi-domain concepts 56
WINNER Cooperation mechanism Partially Centralized Approach Loose coupling or Open coupling Exploit the installed base of wireless system Allow the gradual introduction of WINNER network 57
WINNER Cooperation mechanism CoopRRM Placed in ACS or AR Have interfaces with other CoopRRM of the same or different operators Specific RRM (SRRM) Work in a distributed manner Coordinated by the CoopRRM entity 58
WINNER Cooperation mechanism Mobility Management Support the inter-system handover for traffic balancing strategy Decision criteria Admission Control Coverage criteria, Traffic load, User/operator preference, etc. Ensure that the admittance of a new flow or handover flow does not violate the service commitments made by the network to already admitted flows In case of limited resources Reduce requests for connection/flow in question and/or for lower priority flows Resource re-partitioning Handover flows (cell/mode/ran) 59
WINNER Cooperation mechanism Congestion/Load Control Ensure that the system is in stable state Interact with the service level controller In case of limited resources Reduction of requests for flows Attainment of more resources by resource re-partitioning in neighbouring cells Handover of flows to another cell/mode/ran QoS Management Layered scheduling The scheduler 2 Coarse scheduler Be located at the CoopRRM entity The scheduler 1 Intelligent scheduler Be placed at the Access Point/Relay Take care of dynamic link adaptation 60
Reference [1] J. Maner, and M. Kojo, Mobility related Terminology, RFC3753, Jun., 2004 [2] WINNER, D4.1: Identification and definition of cooperation schemes between RANs, internal deliverable, IST-2003-507581 WINNER, Jun., 2004. [3] IEEE P802.21 /D01.00, IEEE P802.21/D01.00 Draft IEEE Standard for Local and Metropolitan Area Networks: Media Independent Handover Services, Mar., 2006. [4] N. Nasser, A. Hasswa and H. Hassanein, Handoffs in Fourth Generation Heterogeneous Networks IEEE Commun. Mag., vol. 44, no. 10, Oct. 2006, pp. 96-103. [5] WINNER, D4.3: Identification and definition of cooperation schemes between RANs final deliverable IST-2003-507581 WINNER, Jun., 2005 [6] IEEE Std 802.16e-2005, Part 16: Air Interface for Fixed and Mobile Broad-band Wireless Access Systems, Feb. 2006 [7] S. H. Cho et al, Hard handoff scheme exploiting using uplink and downlink signal in IEEE 802.16e system, VTC 2006 Fall [8] IEEE 802.21/D03.00, Draft IEEE Standard for Local and Metropolitan Area Networks: Media Independent Handover Services, December 2006 [9] R. Koodli, Fast Handovers for Mobile IPv6, RFC4068, Jul.,2005 [10] H. Soliman, C. Castelluccia, K. El Malki and L. Bellier, Hierarchical Mobile IPv6 Mobility Management (HMIPv6), RFC 4140, August 2005 [11] S. Gundavelli, K. Leung, V. Devarapalli, K. Chowdhury and B. patil, Proxy Mobile IPv6, draft-ietf-netlmm-proxymip6-00.txt, April 8, 2007 61