Mobile/Wireless System Network 이동및무선통신단기강좌 2011.08. 25 건국대학교새천년기념관 (jkim@ajou.ac.kr) School of Electrical and Computer Engineering AJOU University Homepage: http://ajou.ac.kr/~jkim
Agenda Part 1: Mobile/Wireless System MAC Wireless MAC Protocol Overview Performance Analysis Methods for Wireless MAC Protocol IEEE 802.16 System Overview Major Technologies Case Studies Part 2: Handover in Mobile/Wireless System Handover Overview Layer 2 Handover (IEEE 802.16e System based) Layer 2.5 Handover Layer 3 Handover Application Handover Part 3: Mobile/Wireless System Network Network Design Issues Network Architecture/Protocol Stack 2
Wireless Communication Technologies WAN (Wide Area Network) -Large coverage, High cost Mobility Outdoor Indoor Vehicle Walk Stationary Walk Stationary/ Desktop 2G cellular 3G cellular IEEE802.11 802.15.1 802.15.4a/b 802.15.3 802.15.3a RFID, Sensor network 0.1 IMT-Advanced IEEE802.16 1 10 100 Transmission Rate MAN (Metropolitan Area Network) - Large coverage, Moderate cost LAN (Local Area Network) - Hot Spots, Moderate cost PAN (Personal Area Network) - Connectivity, Low cost 400 BAN (Body Area Network) - Identification, Low cost 1000 Mbps 3
Wireless Communication Technologies 4
Part 1: Mobile/Wireless System MAC - Wireless MAC Protocol Overview - Perfomance Analysis Methods for Wireless MAC Protocol - IEEE 802.16 Systems Overview - Major Technologies - Case Studies 5
Wireless MAC Protocol Classification Wireless MAC Protocols Contention-Based Hybrid Contention-Free Dynamic Resolution Static Resolution Dynamic Allocation Static Allocation Time of arrival high priority to oldest one Probabilistic ID Probabilistic Reservation Exponential Backoff IEEE 802.3/11/16 Binary Tree RFID Aloha CSMA IEEE 802.11e IEEE 802.15.3 IEEE 802.15.4 PRMA DOCSIS IEEE 802.16 RFID : Radio Frequency ID, CSMA : Carrier Sense Multiple Access, PRMA : Packet Reservation Multiple Access Token Passing MSAP BRAM TDMA FDMA CDMA OFDMA DOCSIS : Data Over Cable Service Interface Specification, MSAP : Mini Slotted Alternating Priority, BRAM : Broadcast Recognition Access Method 6
Wireless MAC Protocol Classification IEEE 802.15.3 MAC Frame Structure (IEEE Std 802.15.3-2003) Super frame #m-1 Super frame #m Super frame #m+1 Beacon #m CAP CFP (Contention Free Period) Asynchronous Isochronous Asynchronous Isochronous Beacon #m Contention Access Period MCTA1 MCTA2 CFP (Contention Free Period) CTA 1 CTA 2 CTM n-1 CTA n CSMA/CA Data/Control 1,000 ~ 65,535μs S-ALOHA Data/Control TDMA Data - MCTA : Management Channel Time Allocation 7
Wireless MAC Protocol Performance Performance Metrics Throughput MAC Level Throughput (Goodput): MAC Layer Data Rate (bits/sec) Channel Throughput : The fraction of time that useful information is carried on the channel Packet Delay (Access Delay) The time from the moment a message is generated until it makes it successfully across the channel Packet Drop Probability The probability is that a packet is dropped 8
Wireless MAC Protocol Performance Performance Analysis Method Rigorous Probability Based Binary Tree Based Algorithm : Switching system, RFID Anti-collision etc. Markov Chain Model Slotted Aloha (finite user model), Binary Exponential Backoff algorithm (CSMA/CA) Characteristics Exact analysis method High Computational Complexity M/G/1 Busy Period Analysis Slotted Aloha (Infinite user model), CSMA/CA Characteristics Difficult to model the system and to find the probability distribution TFA (Transient Fluid Approximation) Slotted Aloha, CSMA/CA Characteristics Low Computational Complexity, Easy to model the system Need the verification using the simulation 9
Slotted Aloha 성능분석 - Infinite User Model : M/G/1 Busy Period Analysis - Finite User Model : Markov Chain Analysis 10
Slotted Aloha (M/G/1 Busy Period Analysis) System model Infinite population Packets transmission time : T Packet arrival (Poisson distribution) : λ packet/sec Offered load (new arrival + backlogged arrival) : g Total average number of transmission per slot : G =gt I : Idle period, B: Busy period, U : Useful period Throughput (S) : EU [ *] U S = = EC [ *] B+ I Cycle Busy Period Cycle Idle Period Slot : colliding packets : successful slots 11
Idle Period A random variable describing the number of slots in the idle period : I * The probability of some packets P[ I* = 1] = P[ Some packets scheduled in first slot] = 1- P[ No packets scheduled in first slot] = 1 gt gt PI [ * 2] e = = (1 e ) In general, the length of the idle period is seen to be geometrically distributed gt k 1 gt ( ) ( ) PI [ * = k] = e 1 e k=1,2,... Average length of idle period 1 I = 1 e gt 12 gt e P () t = k ( gt ) k e k! ( gt )
Busy Period The number of slots in the busy period : B * Packets must be scheduled for transmission in each and every one of the first k-1 slots and none scheduled in the kth slots gt k 1 gt ( ) ( ) PB [ * = k] = 1 e e k=1,2,... Expected value of B 1 B = e gt 13
Useful Period and Throughput The probability that a given slot in the busy period is successful gt gte gt 1 e k gt ( B* k) gt B* gte gte PU [ * = k B*] = 1,0 k n gt gt k 1 e 1 e EU [ * B*] = B* gte 1 e gt gt gt gte U= EU [ ] = EEU [ [ * B*]] = B 1 gt e Throughput (S) EU [ *] U gt S = = = gte = Ge EC [ *] B+ I G 14
Slotted Aloha (Markov Chain Analysis) System model Finite number of users Number of users : M (each with a single buffer) Packets transmission time : T (slot duration) Thinking state (No ready packet) Packet generation probability : σ Backlogged state (Transmission was unsuccessful) Packet retransmission probability : v Let N*( k) denote the number of backlogged users at the beginning of the kth slot Throughput (S) : expected fraction of slots containing useful transmission S = P suc 15
Steady-State Probability Steady-State Probability Let Let π i p ij be the steady-state probability of the system being in state i π i = limk Pr[ N*( k) = i] be the steady-state transition probability p = lim Pr[ N*( k) = j N*( k 1) = i] ij k Π=ΠP State Transition Rate Diagram of Finite Population Aloha The number of backlogged users 0 1 2 i M From 01 i-1 To i-1 i 16 To M i+2 i+1 From i+1
State Transition Probability j i Pr[i backlogged users transmit in a slot / j in backlog]= v (1 v) i M j Pr[i thinking users transmit in a slot / j in backlog]= σ (1 σ) i j i i M j i p ij 0 j < i 1 i 1 M i iv(1 v) (1 σ ) j = i 1 i 1 M i M i 1 i 1 iv(1 v) (1 σ) + ( M i) σ(1 σ) (1 v) j = i = M i 1 i ( M i) σ(1 σ) 1 (1 v) j = i+ 1 M i j i M j σ (1 σ) j > i+ 1 j i 17
Performance Analysis of Slotted Aloha Total throughput (S) P suc ( i) = Pr[Successful slot/ i users in backlog] = v M i σ σ + iv v σ i M i 1 i 1 M i (1- ) ( ) (1 ) (1 ) (1 ) M S = P = E[ P ()] i = P () i π suc suc suc i i= 0 As a special case, we do not distinguish between backlogged packets and new packets (v = σ) P ( i) = Mσ(1 σ) M suc 1 S= EP [ ( i)] = Mσ(1 σ) M suc When Mσ = G, M 1 G S = G 1 M 1 M S = Ge G 18
Throughput Graph with Finite and Infinite Number of Users Red Curve: Blue Curves: S = Ge G M 1 G S = G 1, M = 4, 7, 10, 13, 16, 19 M 0.45 0.4 M increases 0.35 0.3 Throughput (S) 0.25 0.2 0.15 0.1 M increases 0.05 0 0 0.5 1 1.5 2 2.5 3 Offered load (G) 19
Performance Analysis of Slotted Aloha Expected delay When the system is in state i there are M-i thinking users each generating packets in every slot with probability σ Average delay b S = E[( M i) σ ] = ( M i) σπ = ( M N) σ N : the average number of backlogged users : the average rate at which packets join the backlog N/ b: the average amount of time spent in the backlog (by Little s formula) (S-b)/S : a fraction of the packets is never backlogged (need only 1 slot ) b/s : a fraction of the packets suffers the backlog delay S b b N N 1 M D = 1+ + 1 = 1+ = 1 + S S b S σ S 20 i (1)
Delay vs. Throughput M increases, Delay (with saturated throughput) increases Expected Delay (D) 10 4 10 3 10 2 M=10 M=20 M=30 M=40 M=50 M increases 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 Throughput(S) 21
IEEE 802.16 Systems 22
IEEE 802.16 Overview Wireless Metropolitan Area Network Broadband Wireless Access Coverage area : 1 Km Max Data Rate : 120Mbps~ IEEE 802.16 Air Interface Standard IEEE 802.16 : Air Interface (MAC and 10 ~ 66 GHz PHY) WiMAX forum coordinating interoperability testing Interoperability documentation in development P802.16a : amendment, 2 ~ 11 GHz Licensed Licensed-exempt 802.16 Standard defines 4 PHY Mode WirelessMAN-SC (Single Carrier) WirelessMAN-SCa WirelessMAN-OFDM WirelessMAN-OFDMA SS SS BS SS Metropolitan Area 23 SS
IEEE 802.16 TGs TG1 Air Interface (MAC and 10 ~ 60 GHz PHY) TGa : Amendment 2, PHY spec. for 2 ~ 11 GHz TGc : Amendment 1, Detailed System Profiles for 10 66 GHz TGd : Amendment 3: Detailed System Profiles for 2-11 GHz TGC : TGC/C1 : Protocol Implementation Conformance Statements for 10-66 GHz WirelessMAN-SC Air Interface TGC/C2 : Test Suite Structure and Test Purposes (TSS&TP) for 10-66 GHz WirelessMAN-SC Air Interface TGC/C3 : Radio Conformance Tests (RCT) for 10-66 GHz WirelessMAN- SC Air Interface 10-66 GHz WirelessMAN-SC Air Interface TGe : Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands (Mobile Wireless MAN) TG2 : Coexistence of Fixed Broadband Wireless Access Systems TGa : amendment to IEEE Std 802.16.2 24
FDD vs. TDD FDD TDD The uplink and downlink channels are on separate frequencies. DownLink UpLink 0.5 Sec / 1 Sec / 2 Sec Broadcast Full Duplex Capable SS Half Duplex SS #1 Half Duplex SS #2 The uplink and downlink transmissions share the same frequency but are separated in time Bandwidth Request Slots DownLink- MAP UpLink-MAP Down Link Subframe Adaptive Uplink Subframe Frame j-2 Frame j-1 Frame j Frame j+1 Frame j+2 25
Frame Structure of IEEE 802.16 OFDMA TDD Mode Subchannel logical number s s+1 k k+1 k+3 Preamble FCH DL_MAP DL burst #1 (carrying the UL_MAP) DL burst #2 OFDMA symbol number DL burst #3 DL burst #4 DL burst #5 DL burst #6 CQICH, ACK CH Ranging UL burst #1 UL burst #2 UL burst #3 UL burst #4 Preamble FCH DL_MAP s+l DL TTG UL RTG One sub-channel Slot Slot Slot PUSC : Partial usage of subchannels FUSC : Full usage of subchannels Slot DL PUSC : two OFDMA symbols FCH : Frame control header Slot DL FUSC : one OFDMA symbol TTG : Transmit/receive transition gap UL PUSC : three OFDMA symbols RTG : Receive/transmit transition gap DL/UL AMC : two, three or six OFDMA symbols 26
IEEE 802.16 Frame Structure The frame structure Preamble: time/frequency synchronization FCH: MAPs lengths, modulation and coding, usable subcarriers DL_MAP & UL_MAP: Burst profile (time, frequency, modulation, coding) DL/UL data bursts UL control channel Ranging, CQI (Channel Quality Indicator) feedback, UL acknowledgement (ACK) 2 types of subcarrier permutation mode in 802.16 OFDMA The distributed subcarrier permutation mode PUSC, OPUSC, FUSC or OFUSC mode The adjacent subcarrier permutation mode AMC mode -OxUSC : Optional x Usage Sub-Channel 27
Adaptive Burst Profiles Burst profile Modulation and FEC (Forward Error Correction) Dynamically assigned according to link conditions Burst by burst, per subscriber station Trade-off capacity vs. robustness in real time Roughly doubled capacity for the same cell area 28
Localized and Distributed Resource Allocation Adjacent Subcarrier Allocation (AMC) Make better use of multiuser diversity Low velocity user Band AMC scheduler Distributed Subcarrier Allocation (FUSC, PUSC) Average intercell interference, avoid deep fading by selecting subcarriers pseudo randomly High velocity user Diversity scheduler Subcarrier allocated to User 1 Subcarrier allocated to User 2 Combined OFDMA Signal 29
UL Control Channel: Ranging Purpose Time synchronization and power control in uplink channel Applications Initial and HO ranging: network entry and initialization Periodic ranging: mobility provisioning Bandwidth request ranging: contention-based bandwidth request General Procedure Ranging subchannel allocated by UL-MAP message An MS randomly selects a CDMA ranging code in a subset of ranging codes A BS sends RNG-RSP message with status = success A BS allocates a bandwidth by UL-MAP message to the MS The MS transmits RNG-REQ message and continues with regular network entry 30
UL Control Channel: CQICH and ACK CQICH Allocated to an MS using a CQICH control IE Used to report the DL CINR (Carrier-to-Interference-plus-Noise Ratio) This channel occupies one UL slot in the FAST-FEEDBACK region allocated through UL-MAP message For diversity sub-channels An MS reports the average CINR of the BS preamble For band AMC sub-channels An MS reports the differential of CINR values of five selected frequency bands UL ACK Channel To support HARQ ACK Allocated using a HARQ ACK region allocation IE The MS can quickly transmit ACK or NACK feedback for DL HARQenabled packet data using this UL ACK channel 31
IEEE 802.16e Functional Structure Upper layer Application service Traffic Data Traffic Data Traffic Data CS SFID-CID mapping MAC SDU MAC MAC SDU SDU Control flow Message flow Handover module (Backbone communication: BS only) MAC management Fragmentation / De-fragmentation ARQ (Selective Repeat) Scheduler (UGS, rtps, ertps, nrtps, BE) Diversity Band AMC scheduler scheduler Fragment Fragment of Fragment MAC SDU of Fragment MAC SDU of MAC SDU of MAC SDU Non-ARQ Queue Fragment Fragment of MAC SDU of MAC SDU Scheduled Block Block Block Block ARQ Queue Block Block MAC layer PHY layer Ranging Mobility (SS only) CDMA code DL/UL - MAP MAC PDU Concatenation / Deconcatenation HARQ PHY PDU Resource allocation CQI SINR / PER modeling le b m a re P Header F C H L DP A -M L UP A -M Subheader Sub- Payload Header header MAC PDU Bur st 2 Burst 1 t rs u B 3... t rs u B 4 MAC PDU l e n a l c h tro n c o L U Payload MAC PDU Burst Burst Burst Burst 1 Burst 2 Burst 2 Burst 2 Burst 3 Burst 5 32
Convergence Sub-layer CID Mapping Classifier assign SDU to CID according to SSID, destination IP sour./dest. address, TOS field, Port Number, etc. Related to Grant per SS or Grant per Connection discipline Upper Layer Upper Layer SDU CS Layer SAP Reconstitution SDU SAP Classifier CS Layer CID 1 CID 2 CID 3 CID n {SDU, CID, } SAP {SDU, CID, } SAP SAP : Service Access Point 33
Scheduling Types Service UGS ert-ps rt-ps nrt-ps BE Support non real-time service flows based on polling basis Best-effort Definition Support fixed size realtime service at periodic interval Support variable size real-time service at periodic interval Support variable size real-time service based on polling access Application VoIP without silence suppression VoIP with silence suppression Variable size vocodec MPEG video FTP HTTP QoS Parameter Maximum Sustained Traffic Rate Maximum Latency Tolerated Jitter Maximum Sustained Traffic Rate Minimum Reserved Traffic Rate Maximum Latency Minimum Reserved Traffic Rate Maximum Sustained Traffic Rate Maximum Latency Minimum Reserved Traffic Rate Traffic Priority Traffic Priority - UGS :Unsolicited Grant Service - ertps : extended real-time Polling services - rtps : real-time Polling Service - nrt-ps : non-real-time Polling Service - BE : Best Effort 34
UGS (Unsolicited Grant Service) Scheduling Scheme Constant bit rate: VoIP service without silence suppression Periodically allocates a grant without a bandwidth request process To reduce the bandwidth request delay and signaling overhead Basic data transmission BW request delay and signaling overhead by (1) Affected by traffic load UGS Periodic BW allocation can reduce the BW request process 35
rtps (real-time Polling Service)/nrtPS Scheduling Scheme Variable bit rate: video streaming service (MPEG4), FTP service Periodically allocates a bandwidth to send a bandwidth request message PI of rtps is generally smaller than that of nrtps rtps/nrtps Periodic polling can avoid a random access process 36
ertps (extended real-time Polling Service) Scheduling Scheme Variable bit rate with a strict delay constraint: VoIP service with silence suppression Periodically allocates a grant and uses a Piggyback scheme to change a grant size Problem of UGS ertps Piggyback using the remained BW BW-REQ message through the allocated BW Reduce the wasted BW and signaling overhead Problem of rtps 37
BE (Best Effort) Scheduling Scheme Delay tolerable service: HTTP Contention-based bandwidth request Bandwidth request ranging Uses CDMA code in OFDMA PHY mode to reduce the collision probability Contention resolution protocol: Truncated binary exponential backoff (BEB) BE 38
Bandwidth Request Methods Bandwidth request SSs use to indicate to the BS that they need UL bandwidth allocation Stand-alone BR header, Piggyback request (Grant management subheader) All requests for bandwidth shall be made in terms of the number of bytes Two types of BR Incremental BS shall add the quantity of bandwidth requested to its current perception of the bandwidth needs of the connection. Aggregate BS shall replace its perception of the bandwidth needs of the connection with the quantity of bandwidth requested. The Type field in the BR header indicates whether the request is incremental or aggregate. 39
Polling A BS allocates bandwidth sufficient to respond with a BR Unicast Polling All PHY modes A BS allocates sufficient bandwidth for an SS to respond with a BR Multicast or Broadcast Polling SC (Single Carrier) PHY and OFDM PHY If insufficient bandwidth is available to individually poll many inactive SSs, some SSs may be polled in multicast groups or a broadcast poll may be issued. The contention resolution algorithm is applied Initial Ranging Period Contention Period Data Transmission Period of SS 1 Data Transmission Period of SS N Request Bandwidth Collision Request Bandwidth 40
MAC PDU Transmission MAC PDUs are transmitted in PHY bursts A single PHY burst can contain multiple Concatenated MAC PDUs The PHY burst can contain multiple FEC blocks MAC PDUs may span FEC block boundaries The TC layer between the MAC and the PHY allows for capturing the start of the next MAC PDU in case of erroneous FEC blocks MAC Message Header Subheader SDU 1 SDU 2 MAC PDUs Burst PDU 1 PDU 2 PDU 3 PDU 4 PDU 5 P FEC 1 FEC 2 FEC 3 - P : Preamble 41
Case Study 1: AMR Codec based Dynamic UL BW Req./Allo. Scheme Motivation Main QoS Requirement: Sensitive to delay requirement Main Traffic Features of the VoIP Service: VoIP traffic rate is variable Repetition of the Cycle of the talk-spurt and silent-period Talk-spurt: traffic rate can be variable according to the network condition (AMR, EVRC) Silent-period: Silence descriptor (SID) frame can be generated with different period or random interval History of the UL BW Req./Allo. Scheme for VoIP Service To meet delay requirement To improve the system efficiency (ON/OFF period) To improve the system efficiency (Traffic Rate Variable in Talk-spurt) To improve the system efficiency (Traffic Rate Variable in Silent-period) - Persistent BW Allo. Scheme (UGS in DOCSIS) - Dynamic BW Allo. Scheme (UGS-AD in DOCSIS and rtps in IEEE 802.16) - Dynamic BW Allo. Scheme (ertps in IEEE 802.16e) -??? 42
Case Study 1: AMR Codec based Dynamic UL BW Req./Allo. Scheme For the AMR Speech Codec Main Traffic Features: Talk-spurt 20msec, Silent-period 160msec Conventional ertps 43
Case Study 1: AMR Codec based Dynamic UL BW Req./Allo. Scheme Proposed scheme Interworking between App. and MAC Detect the VoIP Speech Codec in App.(AMR) Use the VAD of VoIP Speech Codec Separated Action due to VAD Dynamic Grant Interval Dynamic Grant Size if codec == AMR then if VAD == Talk-spurt then Grant for every 20 msec; else Grant for every 160 msec; end if end if 44
Case Study 1: AMR Codec based Dynamic UL BW Req./Allo. Scheme Numerical Results VoIP Capacity: maximum number of supportable VoIP users Throughput : Received bits per second The proposed algorithm can increase the VoIP capacity by 26% compared to the conventional ertps S.M Oh, S.H. Cho, J.H Kim, J.H Kwun, An Efficient Uplink Scheduling Algorithm with Variable Grant-Interval for VoIP Service in BWA systems, IEICE Trans. Commun., VOL.E91-B, NO.10 OCTOBER 2008. 45
Case Study 2: MPEG4 Codec based Dynamic UL BW Req./Allo. Scheme Motivation QoS Requirement: Video Telephony (delay < 50 msec in wireless networks) Main Traffic Feature for MPEG4: Repetition of the Group of Picture (GOP) pattern (I frame, B frame, P frame) I frame : ave. 4742 bytes, min 4034, max 5184 B frame : ave. 147 bytes, min 35, max 882 P frame : ave. 259 bytes, min 100, max 1663 Periodically Grant Estimate Grant Size based on GOP pattern rtps Access Delay: > 20 msec ertps Large Wasted Resource Proposed BW Req./Allo. Scheme Large Difference Size among the I, B, and P Frame Merits - Efficiently Use the BW - Reduce the Access Delay 46
Case Study 2: MPEG4 Codec based Dynamic UL BW Req./Allo. Scheme Simulation Results Normalized Resource Utilization (%): Resource for information / Total resource Ave. Access Delay (msec): Average time to send a video frame from SS to BS Normalized Resource Utilization (%) Access Delay (msec) 100 90 80 70 60 50 40 30 20 10 0 UGS ertps rtps Proposed Scheduler 20 18 16 14 12 10 8 6 4 2 0 UGS ertps rtps Proposed Scheduler The proposed algorithm can efficiently use the radio resource by about 99 % and send a video frame with average access delay 11 msec. J. S. Kim and J. H. Kim, "MPEG-4 codec based uplink resource allocation scheme for the video telephony service in IEEE 802.16e/m system," in Proc. CCNC 2010, Las Vegas, USA, 9-12. Jan. 2010. 47
Case Study 3: BW Request Scheme for BE Services (SMS Service) Motivation Main Traffic Feature: Insensitive to delay requirement Conventional BW Req. Scheme: Random Access History of the BW Req. Scheme for BE Services in BWA Networks Random Access Direct Contention Scheme - Pure Aloha - Slotted Aloha Indirect Contention Scheme - Short Message BW Req. Scheme (DOSCIS, IEEE 802.16) Should we immediately request the required BW for BE service??? It may be NO collision resolution algo. - Binary Exponential Backoff Algo. It is possible that a BE packet is sent without contention. The system overhead for BW req. can be reduced. (DOCSIS, IEEE 802.16) 48
Case Study 3: BW Request Scheme for BE Services (SMS Service) For the Ranging Mechanism Uplink periodic ranging is required to maintain a connection Conventional ertps Proposed BW Req. Slot is needed BW Req. with Uplink Periodic Ranging Merits - Avoid the Contention - Reduce the System Overhead for the BW Req. Unstable due to Traffic Load 49
Case Study 3: BW Request Scheme for BE Services (SMS Service) Numerical and Simulation Results Uplink throughput: Received bit per second Utilization (for given same traffic load): Used resource / total resource It can improve the system capacity by 11 % compared to that of the conventional system 오성민, 김재현, 김봉찬, 김성완 " 광대역무선통신시스템에서상향링크대역폭요청장치및방법," 국내특허, 출원일 : 2010.02.18 출원번호 : P2010-0014505 50
Part 2: Handover in Mobile/Wireless System - Handover Overview - Layer 2 Handover (IEEE 802.16e System based) - Layer 2.5 Handover - Layer 3 Handover - Application Handover 51
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) RCoA (Regional Care-of-Address) LCoA (On-link Care-of-Address) Router PAR (Previous Access Router) NAR (New Access Router) MAP (Mobility Anchor Point) MAG (Mobile Access Gateway) LMA (Local Mobility Anchor) 52
이동통신망상호공존요인 이동통신망상호공존요인 경제적요인기존통신망의재활용을통한망설치비용절감서비스특성에따른망선택을통한서비스비용절감 기술적요인 단일통신망으로사용자의요구를만족시키기어려움 높은전송속도, QoS, 고속의이동속도 통신망의변경에따른서비스의단절을줄이기위한이동성보장기술필요 53
핸드오버의정의 IETF (Internet Engineering Task Force) The process by which an active MN changes its point of attachment to the network, or when such a change is attempted WINNER (Wireless World Initiative New Radio) The process in which the radio access network changes the radio transmitters or radio mode or radio system used to provide bearer services, while maintaining a defined bearer service QoS and minimum added system load IEEE 802.21 MIH(Media Independent Handover) The process by which a mobile node obtains the preservation of facilities for supporting traffic flows upon occurrence of a link-switch event - J. Maner, and M. Kojo, Mobility related Terminology, RFC3753, Jun., 2004 - WINNER, D4.1: Identification and definition of cooperation schemes between RANs, internal deliverable, IST-2003-507581 WINNER, Jun., 2004 - 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 54
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 N. Nasser et al, Handoffs in Fourth Generation Heterogeneous Networks IEEE Commun. Mag., vol. 44, no. 10, Oct. 2006, pp. 96-103. 55
핸드오버평가척도 척도 정의 필요기술 신뢰성 (Reliability) 핸드오버이후서비스의품질이일정하게유지되는정도 핸드오버를수행할단말에게제공할수있는서비스품질정보를기반한핸드오버결정기술 연결성 (Seamless) 간섭회피율 (Interference Prevention) 부하제어 (Load Balancing) 핸드오버를수행하는동안서비스의품질이일정하게유지되는정도 핸드오버수행단말의무선채널과동일또는인접채널을사용하는단말로인한간섭에대한회피정도 기지국또는접속점의가용한자원을균일하게유지하기위한제어 핸드오버의이전에이동단말에관한정보를상호교환하는기술 핸드오버제어정보의재전송기술 송신전력을제어하는전력제어기술 SINR 에따른핸드오버결정기술 간섭회피기술 기지국간부하제어기술 셀부하정보를기반으로하는핸드오버결정기술 핸드오버 수행횟수 품질저하극복및서비스요구를충족시키지위해시행되는핸드오버횟수 상대적임계값을이용한핸드오버결정기술 N. Nasser et al, Handoffs in Fourth Generation Heterogeneous Networks IEEE Commun. Mag., vol. 44, no. 10, Oct. 2006, pp. 96-103. 56
계층별핸드오버기능 Layer 4 or upper Layer 3 Layer 2.5 Layer 2 57
2 계층이동성보장기술 핸드오버관련정보측정기술 (Scanning) 트리거 (Initiation) 핸드오버결정 (Decision) 핸드오버수행 (Execution) 상향링크정보를이용한핸드오버 58
2 계층이동성보장기술과정 Trigger threshold Hysteresis Serving cell Target cell Measurement Trigger Decision & Execution 59
핸드오버관련정보측정기술 현재통신조건에적합한무선통신망을찾기위한정보의획득방법 측정정보물리계층측정정보 Received Signal Strength Indicator(RSSI), Signal to Interference plus Noise Ratio(SINR), etc. 상위계층측정정보 Cell load, User preference, QoS, etc. 측정대상 Preamble signal, feedback report, pilot channel 60
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) IEEE Std 802.16e-2005, Part 16: Air Interface for Fixed and Mobile Broad-band Wireless Access Systems, Feb. 2006 61
핸드오버관련정보측정기술 : IEEE 802.16e 의 Association Scanning 동안예상기지국과정보교환 Ranging parameter(power offset, CDMA code, etc.) 와 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 62
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) IEEE Std 802.16e-2005, Part 16: Air Interface for Fixed and Mobile Broad-band Wireless Access Systems, Feb. 2006 63
트리거 (Trigger) 측정된정보를기반으로핸드오버알고리즘에특정한행동을취하도록명령하는것 측정된링크품질이임계값이하일경우 스케닝, 핸드오버시작 L2 트리거 물리적인정보를기반으로한트리거 Signal strength, Interference level, BER/PER(Packet Error Rate), Power control results 서비스측면에서알고리즘에의한트리거 QoS violation, CAC&CF(Connection Admission Control & Connection Forwarding), Location, Velocity, A prioriknowledge(history, preference), Service availability 64
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 HO-confirm (Ack, same QoS class) 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, same QoS class) HO-pre-notification-response (Ack, same QoS class) IEEE Std 802.16e-2005, Part 16: Air Interface for Fixed and Mobile Broad-band Wireless Access Systems, Feb. 2006 65
핸드오버결정 (Decision) 핸드오버결정요인 수평적핸드오버 신호품질및망내자원상황 수직적핸드오버 망내부하, 서비스가격, 지원가능한통신속도, 보안, 이동속도및전력소모 IEEE 802.16e MS initiated & decision, BS initiated & MS decision Signal strength, cell load, QoS level 66
핸드오버결정 : IEEE 802.16e 의핸드오버결정 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 Decision to execute handover MOB_HO_Indicaiton (Time=L frames) Release channel with BS#1 Decision to cancel handover MOB_HO_Indicaiton Data traffic 67 IEEE Std 802.16e-2005, Part 16: Air Interface for Fixed and Mobile Broad-band Wireless Access Systems, Feb. 2006
핸드오버수행 Serving BS 와의연결을종료하고 target BS 와의무선링크를재설정하는과정 Seamless handover (Handover interruption time 고려 ) 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 3GPP TSG-SA Working Group 1, TSGS1#4(99)529, 5-9 July 1999 68
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 69
핸드오버수행 : IEEE 802.16e 의핸드오버수행 OFDM PHY Non-contention based ranging Using Fast ranging IE() when scanning has done with association OFDMA PHY Contention based ranging Without association MS 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) CDMA Code for Handover Ranging RNG-RSP (Raging status = Success) UL_MAP : CDMA Allocation IE() RNG-REQ (CDMA code + Contention) (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 Bandwidth Request (BR) BS #2 (Target) Interruption time Interruption time UL-MAP IE() : CDMA Allocation IE() BR Header Complete Initial Network Entry (after handover) IEEE Std 802.16e-2005, Part 16: Air Interface for Fixed and Mobile Broad-band Wireless Access Systems, Feb. 2006 70
IEEE 802.16e 의 2 계층핸드오버과정 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, same 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) IEEE Std 802.16e-2005, Part 16: Air Interface for Fixed and Mobile Broad-band Wireless Access Systems, Feb. 2006 71
Case Study 1: 상향링크정보를이용한핸드오버 연구배경 IEEE 802.16e 와같은 TDD OFDMA 에서는셀내의 MS 의위치와분포에따라 Uplink 와 Downlink 의채널품질이다를수있음 주기적인 Scanning 으로인한통신두절이있음 특징 주기적인 Scanning 구간대신핸드오버요청시에만주변기지국의신호를측정 핸드오버결정요인으로 Uplink 와 Downlink 를모두고려
Case Study 1: 상향링크정보를이용한핸드오버과정 MS BS#1 (Serving) BS#2 (Target) BS#3 (Target) Th 1 : Uplink 를고려한핸드오버결정임계값 Th 2 :AMC 유저를위한핸드오버임계값 Th 3 : 상향링크를고려한핸드오버대상기지국결정임계값 (UL hysteresis 사용 ) Th 4 : 통신을위한최소 Downlink 신호품질임계값 Th 5 : 하향링크를고려한핸드오버대상기지국결정임계값 (UL hysteresis 사용 ) Th 6 : 통신을위한최소 Uplink 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 S. H. Cho et al, Hard handoff scheme exploiting using uplink and downlink signal in IEEE 802.16e system, VTC 2006 Fall
Case Study 1: 상향링크를이용한핸드오버성능평가 OPNET 을이용한상향링크신호측정상향링크사용자의분포에따른비대칭적인상향링크신호품질상향링크를고려하여상향링크의신호감쇠로인한 outage probability 를줄일수있음 <Uplink> <Downlink> BS2 BS1 74
2.5 계층이동성보장기술 IEEE 802.21 Media Independent Handover (MIH) 75
IEEE 802.21 MIH 최적화된핸드오버를수행하기위하여필요한망에관련된정보와무선링크의정보의제공 2 계층이동성관리기술의정보와상위계층이동성관리기술의연동 MIH 제공서비스 Event services Command services Information services MIH Events < MIH 프로토콜스택 > SIP MIPv4 MIPv6 HIP Upper Layer (L3 and above) MIH Commands Information Service MIH function Link Events Link Commands Information Service IEEE 802.3 IEEE 802.11 IEEE 802.16 3GPP 3GPP2 Lower Layer (L2 and below) IEEE 802.21/D03.00, Draft IEEE Standard for Local and Metropolitan Area Networks: Media Independent Handover Services, December 2006 76
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 77
IEEE 802.21 MIH: MIH Services Media independent event services 하위계층의상태변화를상위계층에알리는역할수행 이벤트생성위치에따른분류 Remote event : 다른망요소에서생성된이벤트 Local event : 동일한망요소에서생성된이벤트 이벤트인식위치에따른분류 Link event : PHY, MAC MIH MIH event : MIH L3+ 78
IEEE 802.21 MIH: MIH Services 이벤트내용에따른분류 State change event MAC 또는 PHY 계층의상태변화 ex) Link_Up, Link_Down Parameter event 링크계층파라미터의변화 ex)link_parameter_change Predictive event 과거와현재의조건을기반으로링크의변화예측정보알림 ex)link_going_up, Link_Going_Down Synchronous event 링크계층동작에관한정보알림 ex)link_handover_complete Transmission event 링크계층에서상위계층 PDU 의전송상태알림 ex)sdu_transmit_status 79
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 80
3 계층이동성보장기술 Mobile IP Fast Mobile IPv6 (FMIPv6) Hierarchical MIPv6 (HMIPv6) Proxy Mobile IPv6 (PMIPv6) 81
Mobile IP 설계목적 특징 IP 를사용하는 MN 의이동시에도연결을유지하기위하여개발됨 MN 의이동에의한 PoA 의변경시 IP 주소의변경이요구됨 이동전에연결한 TCP 연결을유지하기위해서는 IP 주소의유지가필요 두개의 IP 주소 (Home address, Care of Address) 를유지 기본적인과정 Agent discovery MN 의이동에따른 IP 주소의변경필요성을발견하는과정 Registration 변경된 IP 주소를변경하는과정 Data transfer 변경된 IP 주소로 IP 패킷을전송하는과정 82
Mobile IP: 동작절차 Agent Discovery Registration Data transfer Binding cache Home Life CoA address time HA Src. Dest. CN MN Payload CN 4. Registration Reply Encapsulation 3. Registration Request FA1 HA CoA CN MN Payload FA2 Home Visitor table HA Link level Life address address address time 1. Agent Solicitation Message 2. Agent Advertisement Message AP1 AP2 CoA generation MN 0. Movement MN 83
Fast Mobile IPv6 (FMIPv6) 설계목적 특징 경로최적화를통한망효율성향상 핸드오버에의한패킷손실감소 Binding Update 에의한핸드오버지연감소 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 R. Koodli, Fast Handovers for Mobile IPv6, RFC4068, Jul.,2005 84
Fast Mobile IPv6 (FMIPv6): 동작절차 CN 4. HI Old PoA 5. HAck New PoA 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 85
Hierarchical MIPv6 (HMIPv6) 설계목적 MIPv6 에서잦은핸드오버시 MN 과 CN 사이에발생하는 Binding update 의부하를줄이기위함 특징 망을계층구조로관리 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 H. Soliman, C. Castelluccia, K. El Malki and L. Bellier, Hierarchical Mobile IPv6 Mobility Management (HMIPv6), RFC 4140, August 2005 86
Hierarchical MIPv6 (HMIPv6): 동작절차 CN HA MAP1 6. Binding Update (RCoA1 RCoA2) (LCoA2 LCoA3) 3. Binding Update Acknowledge MAP2 7. Binding Update Acknowledge AR1 AR2 AR3 AR4 2. Binding Update 1. Router Advertisements 5. Router Advertisements (RCoA1 RCoA1) Care- of-address (LCoA1 LCoA2) (RCoA1) (LCoA1 ) MN 0. Movement 4. Movement Care- of-address Care- of-address (RCoA1) (RCoA2) 87
Proxy Mobile IPv6 (PMIPv6) 설계목적 특징 IPv6 지원망에서단말이이동관련시그널에관련하지않고이동성을제공하기위함 네트워크기반 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 S. Gundavelli, K. Leung, V. Devarapalli, K. Chowdhury and B. patil, Proxy Mobile IPv6, draft-ietf-netlmm-proxymip6-00.txt, April 8, 2007 88
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 MAG (Mobile Access Gateway) - LMA (Local Mobility Anchor) -AAA : Authentication Authorization Accounting 89
4 계층이동성보장기술 SIP Application layer handover 90
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 - J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Sparks, M. Handley, and, E. Schooler, SIP : Session Initiation Protocol, RFC3261, Jun., 2002 - Yung-Mu Chen et el. SCTP-based handoff based on MIH triggers information in campus networks, Feb., 2006, ICACT 2006, vol(2), pp. 1297-1301 91
SIP(Session Initiation Protocol) : Session initiation procedure 5.re-INVITE 1. INVITE 1. INVITE Location/Redirect Server 2. 302 (Moved Temporarily) Proxy 3. ACK Server 4. 180(Ringing) 3. ACK 200(OK) User Agent Proxy Server Proxy Server AP AP MN MN MN 92
Application layer handover 핸드오버지연을최소화시키기위하여망의도움없이다중경로 / 다중세션기술을사용하여접속망을변경하는과정 배경 Coexistence 향후통신서비스는 CDMA2000, UMTS, WiBro, WLAN 등의다양한무선통신망이상호공존할것으로예상됨 Multi-interface support 하나의 MN이여러개의 RAT를사용함각 RAT는독립된 interface를가짐 MN은 multi-homing 기술을지원함 오성근, 김재현, 이현진, 사용자단말에의해제어되는끊어짐없는서비스방법, 특허출원중 93
Application layer handover: Reference Architecture User plane Control plane 교환정보 1 사용자정책및서비스정보 Application Transport Network a Application program/ User Interface SDP RTP/RTCP SIP 4 Service Continuity Management 8 SCTP, TCP, UDP IPv4, IPv6, MIP Traffic Junction Management b 5 3 7 1 Information Management QoE Management 6 Session Management 11 Network Selection 9 12 2 2 3 4 5 6 7 8 9 망탐색결과 (RAT정보, 신호세기, 지연 ) 서비스플로우의정보 Time stamp 정보다중세션연결요청 QoS monitoring 정보다중세션연결정보 Sequence 정보사용자선호도 Link c PDCP RRC RLC d 10 e Network Mearsurement 10 11 12 다중라디오연결요청단일 / 다중연결에따른필요자원양경로별 MIMO stream 수, MCS level, BLER 정보 MAC Link Manager 필요기능 Physical PHY Traffic Condition Indicator a 세션간서비스스케줄링기능 b 서버간동기화기능 제어정보데이터패킷 c d e ARQ 동기화기능 사용자중심 MIMO 모드설정기능 RB 요청, 반납및공유요청기능 94
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 95
사용자중심이동성제공 Service flow Service flow AAA server RAN2 modem up RAN 1 GW GW server RAN 2 Session request Measurement Link setup Session Request AAA MN Signal Quality for RAN 1 Service Flow 1 Flow 2 IP1 IP2 Data Data Signal Quality for RAN 2 Measurement trigger MIH Handover magt. Handover init. trigger MIH Handover magt. Handover decision trigger MIH Handover magt.
Part 3: Mobile/Wireless System Network - Network Design Issues - Network Architecture/ Protocol Stack 97
Wireless Network Design Issues: 1-tier or 2-tier Network Architecture 1-tier or 2-tier Network Architecture 98
Wireless Network Design Issues: 1-tier and 2-tier 장 단점 Consideration of Function Positioning in Wireless Networks Functions 2-tier ASN model 1-tier ASN model L3 Handover Functions Positive if in an ASN-GW Negative L2 Handover Functions Positive if in a BS Positive if in a BS Related End-to-End QoS performance metric Transmission Delay Delay Jitter Packet Loss Rate Transmission Delay Delay Jitter Packet Loss Rate ARQ Functions Positive for handover process if in an ASN-GW Negative for handover process Transmission Delay Delay Jitter Packet Loss Rate Admission Control Positive if in an ASN GW Negative Call Dropping Rate Scheduler Positive if intercell coordination is required Positive if fast feedback is required Data Rate Transmission Delay Intercell Interference Mitigation (IIM) Functions Positive to centralized scheme Positive to distributed scheme Data Rate Packet Loss Rate 99
Wireless Network Design Issues : QoS and Mobility Provisioning Wireless Network Architecture QoS Policy Server Positioning SIP Server Positioning 무선망설계고려사항 - 백본링크단절시연결성 - MN/MR의이동성 + 통신환경의잦은변화 MeR (Mesh Router) + 망토폴로지변화 - MN 무선통신인터페이스 - MR 무선통신인터페이스 - MeR 무선통신인터페이스 MR (Mobile Router) - MN 무선통신인터페이스 - MR 무선통신인터페이스 - MeR 무선통신인터페이스 MN (Mobile Node) - MR, MeR 무선통신인터페이스 100
Wireless Network Design Issues: Mobility Provisioning Considerations of Network Architecture Design 무선망 IP 도메인구성방안 101
Wireless Network Design Issues: Mobility Provisioning Considerations of Network Architecture Design HA 의위치구성방안 102
Wireless Network Design Issues: Mobility Provisioning Considerations of Network Architecture Design 무선망 subnet 구성방안 103
Wireless Network Design Issues: Mobility Provisioning Considerations of Network Architecture Design 무선망 IP 주소할당방안 104
Wireless Network Design Issues: Protocol Stack for Mobility Provisioning PMIP & SIP SIP 를사용할경우의요구기술 PMIP 를사용할경우의요구기술 MR 이동및공통요구기술 SIP 를위한 trigger PMIP 를위한 trigger 공통요구 trigger Manage ment Application Control plane User plane Manage ment Application Control plane User plane Manage ment Application Control plane User plane plane SDP SIP Client re- INVITE plane SIP Registrar SIP Proxy Proxy update plane SIP Registrar SIP Proxy Proxy update SIP Location re-invite trigger Transport Proxy update trigger Internet Internet Internet Network prefix transfer IP generation Network access Binding update request Binding table or visitor table Binding update Routing table Network access Routing update Buffer Tunneling Binding table or visitor table Binding update Routing table Network access Buffer Tunneling Link establishment HO Trigger Link establishment HO Trigger Buffer Tunneling Buffer Tunneling Event driven command Physical Event driven command Physical Physical Measurement Measurement 105
Wireless Network Design Issues: QoS Provisioning 정책기반 QoS 보장참조망구조설계고려사항 백본링크단절시연결성 > 효율성 백본링크단절시연결성 통신연결 : 상대단말의위치정보 SIP 서버 정책연결 : 저장된정책정보 Policy 서버 SIP 서버 Local SIP Proxy 서버, Local SIP Location 서버, Global 서버유선백본링크연결시 : Global 서버 유선백본링크단절시 : MeR 단 SIP Location 서버 Location 서버간동기화유지 MR-MeR 백본링크단절시 : MR 단 SIP Proxy 서버 Full-Distributed 구조 Policy 서버 정책수행시 PEP PDP 정책결정요청 PEP cache 정책임시저장 MeR 별구분된정책수행고려 Half-Distributed 구조 Local Server SIP/Policy (Proxy, Registrar, Location) PEP: Policy Enforcement Point PDP: Policy Decision Point Global Server SIP (Proxy, Registrar) 106
Wireless Network Design Issues: Protocol Stack for QoS Provisioning End-to-End QoS 보장구조 계층별, 네크워크별 ( 액세스, 백본 ) QoS 보장구조설계 <End-to-End QoS 보장구조 > 107
Control Plane Wireless Network Design Issues: Protocol Stack for QoS Provisioning End-to-End 통신연결시 signaling 에필요한기능설계 <End-to-End QoS 보장구조 > PEP: Policy Enforcement Point PDP: Policy Decision Point 108
User Plane Wireless Network Design Issues: Protocol Stacks for QoS Provisioning End-to-End 통신시 QoS 보장에필요한기능설계 <End-to-End QoS 보장구조 > 109
Network Reference Architecture (UMTS Rel99) Data Center 110
Protocol Stack for UMTS PS service (Data) UMTS Node-B UMTS CRNC UMTS SRNC SGSN GGSN UE Application TCP/UDP IP IP PDCP RLC MAC_d PDCP RLC MAC_d Iu-UP GTP_U UDP/IP Iu-UP GTP_U UDP/IP GTP_U UDP/IP GTP_U UDP/IP PHY_UP PHY PHY DchFP AAL2 DchFP AAL2 DchFP AAL2 PHY_UP DchFP AAL2 AAL5 AAL5 L2 (AAL5) L2 (AAL5) External ATM ATM ATM ATM ATM ATM ATM ATM Phys Air ATM AAL2 ATM AAL2 ATM AAL5 ATM AAL5 Uu Iub Iur Iu-ps Gn PDCP Packet Data Convergence Protocol Iu-UP Iu User Plane GTP GPRS Tunneling Protocol Dch-FP - Dedicated Channel Framing Protocol PHY-UP- Physical Layer User Plane MAC_d Media Access Control for DCH IP - Internet Protocol TCP - Transmission Control Protocol UDP- User Datagram Protocol 111
Protocol Stack for UMTS CS Service (voice) UMTS Node-B UMTS CRNC UMTS SRNC WAG TAG UE Application AMR AMR G.711 RLC RLC Iu-UP Iu-UP MAC_d MAC_d UDP/IP UDP/IP AAL1 PHY_UP PHY_UP DchFP DchFP DchFP DchFP AAL5 AAL5 PHY PHY AAL2 AAL2 AAL2 AAL2 ATM ATM ATM ATM ATM ATM Ethernet Ethernet ATM Phys Air ATM AAL2 ATM AAL2 ATM PVC ATM AAL5 Uu Iub Iur Iu-cs Gn PDCP Packet Data Convergence Protocol Iu-UP Iu User Plane Dch-FP - Dedicated Channel Framing Protocol PHY-UP- Physical Layer User Plane MAC_d Media Access Control for DCH IP - Internet Protocol TCP - Transmission Control Protocol UDP- User Datagram Protocol 112
WiBro Protocol Stack WiBro 프로토콜스택 Servers PSS RAS ACR Application Application TCP/UDP TCP/UDP IP IP Hbis/ GRE Hbis/ GRE WiBro MAC WiBro MAC IP MAC IP ACR Control MAC MAC MAC WiBro PHY Air WiBro PHY PHY 전용선 PHY PHY Ethernet/ POS PHY Hbis: ACR-RAS 간프로토콜 GRE: Generic Routing Encapsulation ( Tunneling Protocol) POS: Packet over SONET 참고 : KRNET 2006 - H1 113
LTE Protocol Architecture 1-tier Network Architecture UE enb MME NAS NAS UE enb RRC RRC PDCP PDCP PDCP PDCP RLC RLC RLC RLC MAC MAC MAC MAC PHY PHY PHY PHY < User Plane> < Control Plane> PDCP: Packet Data Convergence Protocol, NAS: Non Access Stratum [Reference] 3GPP TS 36.300 114
Summary Part 1: Mobile/Wireless System MAC Wireless Channel Variation based Technologies AMC, MIMO, Scheduler, and so on. Application Traffic Feature based Technologies Scheduler, HARQ, and so on. Part 2: Handover in Mobile System L2 : Measurement, Decision, Call Setup L2.5 : Trigger L3 : IP Address Acquisition and Deliver L4+ : Path Selection and Change Part 3: Mobile/Wireless System Network Considerations of Network Design QoS and Mobility Functions Positioning 2-tier Network Architecture 1-tier Network Architecture Fast Transmission 115
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