박노익 5G 네트워크연구실 / 한국전자통신연구원 2016.6
1 Thinking about 5G Network 5G RAT/RAN mmwave, m-mimo, Cloud Virtualization (SDN/NFV) Where are native networking functions for 5G??? New Traffic Contol, New Signaling, New Mobility, New QoS, New NMS, etc. Fronthaul/ Backhaul IoT/V2X/VR/ Network Slicing ICN
GAPs
3 From GPRS 2.5G 3G E1/T1 (Frame Relay) GTP ATM GTP 3G HLR SubSystem GTP 4G IP GTP GTP PDN
Is 4G All-IP Network? Tunnel End Point ID기반의 Switching MME Network GTP Tunnel 로회선을모사 GTP Tunnel GTP Tunnel enodeb SGW PGW 인터넷 PL IP PL IP GTP IP PL IP GTP IP PL IP GTP IP PL IP GTP PL IP PL IP GTP IP 4
5 Usage Scenarios of 5G ITU-R M.[IMT.VISION]
6 Problems : Enhanced Mobile Broadband 4G(LTE) 트래픽집중도심화 GTP Tunnel SGW MME GTP Tunnel 4G Packet Core PGW 모든트래픽이 PGW 를거쳐야통신이가능 Cloud 는 Edge 로 Mobile Edge Computing Mobile Edge Cloud Fog Computing IoT 컨텐츠 / 서비스 /Computing Power 가 Edge 로내려올수없는구조 RU DU MSPP SDH Ring L2 Tunnel GTP Tunnel L2/L3 집선 SW SGW PGW MPLS Tunnel
Problems : Massive MTC 소수의 PGW 에서수많은단말수용 시그널링오버헤드 Network : IP 네트워크 (Connection-less) 서비스 : GTP 기반회선서비스 (Connection-oriented). 하나를보내기위하여약 900 byte 이상의시그널 (Lab. Test) Signaling procedure to send a bit UE enodeb 1. NAS: Service Request 2. NAS: Service Request 3. Authentication/Security 5. Radio Bearer Establishment MME Serving GW PDN GW 4. S1-AP: Initial Context Setup Request 6. Uplink Data 7. S1-AP: Initial Context Setup Complete 8. Modify Bearer Request (A) 12. Modify Bearer Response 11. Modify Bearer Response PCRF 9. Modify Bearer Request 10. PCEF Initiated IP-CAN Session Modification HSS Signaling procedure to receive a bit UE enodeb RNC/BSC MME SGSN S-GW PDN GW 1. Downlink Data 2a. Downlink Data Notification 2b. Downlink Data Notification Ack 2a. Downlink Data Notification 3a. Paging 2b. Downlink Data Notification Ack 3b. Paging 4a. Paging 4b. Paging 5. Service Request Procedure 6a. Stop Paging 6b. Stop Paging Downlink Data E-UTRAN Downlink Data 2G or 3G non DT Downlink Data 3G DT 7
8 Problems : Low Latency Signaling Delay 가크다! NAS Delay: 650ms ~850ms (Service Request, 상용장비측정결과 ) IMS Delay : 1s~2s( 통신사, Vendor comments) Data 전달 Delay (GSMA)
Problems : Mobility Anchor Point 존재로인한비효율성 PGW 간의 Mobility 가정의되지않음 경로 / 자원이용비효율성 Home Fixed Net AAA WiFi AP 이종망간 Mobility 솔루션부재 PMIP 의비효율성 NB AAA RNC SGSN GGSN 3G Core Net. IX MME AAA 9 enb S-GW P-GW 4G Core Net.
Problems : Mobility(Example) PGW SGW SGW PGW SGW SGW SGW 서울에서단말전원을킨사람이부산으로출장후부산지역으로통화 부산 SGW 서울 PGW 부산 SGW 10
11 Problems : Resource / Path / QoS 기지국을벗어난트래픽은터널링되어무조건 PGW 를거쳐야함 MME 인터넷 enodeb SGW PGW 콘텐츠및서비스가가입자접면으로배치되기어려운구조 SER SER Fixed CR IP Network CR ER LGW MME epdg IX Internet GTP Tunnel SGW GTP Tunnel 4G Packet Core PGW
12 Issues of Operators Wired WiBro ACR SER Fixed IP Network (Managed IP Network) CR CR ER SGSN : Serving GPRS Support Node RNC : Radio Network Controller SGW : Serving Gateway PDNGW : Packet Data Network GW ACR : Access Control Router ER : Edge Router PDG : Packet Data Gateway WiFi SER MME QCI 4G Core QCI epdg PDG IX 4G SGW Diffserv PGW Diffserv 3G RNC 3G Core SGSN GGSN Management 계층이너무많다. A 사의경우 7 개의 Management Plane 각 Mgt. Plane 을통합 / 관리하는데돈이더든다. QoS 제어가복잡하다. E-2-E QoS 제어가복잡하다. 개별망의 QoS mapping 체계를만드는데비용이많이든다.
Others say too NGMN To support the diversity of use cases and requirements in a cost-effective manner, the system design should move away from the 4G monolithic design optimized for mobile broadband. In this regard, a rethink of models such as bearers, APNs, extensive tunnel aggregation and gateways is needed. To provide further simplification, legacy interworking must also be minimized, for example towards circuit switched domain in the 2G and 3G networks. A converged access-agnostic core (i.e., where identity, mobility, security, etc. are decoupled from the access technology), which integrates fixed and mobile core on an IP basis, should be the design goal. 4G Americas For local offloading, 4G requires a separate mobile packet gateway (PGW) deployed locally largely because mobile-network-specific tunneling is employed for all traffic. 3GPP handling of mobility entails significant RAN and core network signaling overhead that is unnecessary for devices and applications that are primarily static or nomadic. Because the tunneling encapsulation and de-encapsulation can occur only at special router nodes designed to handle the associated signaling messages, packets cannot always be routed using the shortest path. The network cannot alter whether a users video should be sent over Wi-Fi versus over cellular as a function of network conditions and steer traffic accordingly. The devices have only a small amount of data to send but nevertheless have to go through a full signaling procedure to transmit the data. 13
DIRECTION
15 Clues 데이터망에서회선서비스와같은과금 / 이동성제공필요 - IP 패킷포워딩기능이외사용자별트래픽분 류 / 관리기능이없었다. - 데이터망상에서회선 -like 한서비스제공을 위해기지국부터 PGW 까지 GTP Tunnel 도입 IP flow 기술보편화 - IP Packet들을하나의 flow로인식하고관리할수있음 - 불필요한시그널링도줄일수있다. Mobility 제공용이성 - 이동시에도 IP 주소와상관없이 GTP 로해결 - 터널단위이동성제공 새로운모빌리티 - 단말을식별하는 ID와위치를인식하는 Locator의분리구조가도입 - 3GPP IFOM과같은 Flow 단위의이동성제공필요 데이터계층의기본적인 Security IP 계층에서도된다. - IP 주소가 GTP 내부에숨어버림 - IP-in-IP, GRE 등 - 4G 에서도 IPSec 은적용된다.
16 5G Network R&D Direction Network Sustainability 확보무선기술의세대별진화와무관하게 ( 최소한의변경만으로 ) 운용유지가가능한네트워크기술확보액세스기술특성에무관한공통트래픽제어, QoS 제어구조확보 Unified Network Architecture 5G, WiFi, 유선가입자를수용하는공통된단일네트워크 (3G, 4G : FFS) Network Resiliency 확보 1,000 배트래픽수용을위한네트워크유연성확보 Seamless Service Anytime, Anywhere 이종망간의끊김없는이동성보장및사용자에게최적의망자원이용권보장 Connectionless Service 제공이효율적인구조 MTC, IoT 등 Connection-less Service 수용이용이한경량신호체계확보 Edge Service 제공구조확보모든서비스및콘텐츠가네트워크에지에서제공될수있는구조확보유 / 무선자원의이용효율성증대 ( 극대화 ) 이종무선자원에대한효율적사용및유선자원낭비요소제거 Network Flexibility 보장네트워크가상화기반서비스특성에맞는 Network Slicing 기능구조확보
17 Target Network WiFi Edge 콘텐츠 / 응용서버 통합제어플랫폼 ( 클라우드 ) ( 인증 / 트래픽 / 이동성 ) 5G Core Network (Based on All-IP Managed Network) Home 3G/4G 5G 융합게이트웨이 5G 기지국 4G 5G 비고 Interface Access dependent Access agnostic Unified NAS 지원 Hierarchy 계층구조 Flat 구조 Low latency 지원 Structure central distributed 1000x Traffic 처리지원 control / data plane - 혼잡 control / data plane 분리 NFV / SDN 지원 Protocol GTP base IP base 장비단순화지원 Mobility Static anchoring (P-GW) Dynamic/Distributed anchoring (CGWs) 망효율성지원 Edge networking Specified L-GW Implicit in network architecture Network 단순화지원
18 Access-technology interfacing options ( 출처 : NGMN 5G White paper (2015. 3.))
Reference Model Control plane Entity UCE : Unified Control Entity euce : edge UCE Intra-UCE-C UCE euce euce IntereUCE-C HSS Inter-GW-P CGW CGW Intra-GW-C Intra-GW-P C-AP Intra-GW- NAS 5G-RAN Intra-RAT-P WiFi- RAN WiFi APs Fixed- AN 802.11a/b/g/n... 19 Data plane Entity CGW : Converged Gateway 5G-RAN WiFi-RAN Fixed-AN
Tech. Issues - QoS GTP 기반의비효율적인 EPS 관리를 IP 기반으로단순화 베어러구조를탈피함으로써확장성증대 기존 UE, 베어러, APN, SDF 로구성된복잡한 QoS 관리를 UE 의전체대역제어기반클래스및플로우별대역제어로 QoS 제어효율성증대 제어 / 데이터플레인분리및그에따른플로우별트래픽제어단위지원 Multi-RAT 환경에서의 access-agnostic QoS 제어 4G QoS 제어모델 5G QoS 제어모델 ` GBR1, MBR1 SDF1 5G MBR GBR2, MBR2 GBR1, MBR1 UE UE AMBR ` GBR1, MBR1 APN AMBR SDF2 SDF2 SDF2 UE IP 5G-BS WiFi MBR WiFi-BS GBR3, MBR3 GBR1, MBR1 enb PGW Wired MBR GBR4, MBR4 GBR1, MBR1 Fixed-AN CGW o QoS 제어절차복잡 ( 베어러설정및관리절차와연계 ) o 사용자, 베어러, APN, 클래스 (SDF) 단위의다단계제어로인하여 QoS 운용관리가용이하지않음 o QoS 제어절차의간소화 ( 베어러설정절차없음 ) o 사용자의대역제어에기반한사용자의각플로우또는클래스기반의제어로 QoS 운용관리단순화 o 이기종의다수의엑세스네트워크에대한 accessagnostic 한 QoS 제어제공 20
21 Tech. Issues - Mobility 이동성제어특징 Anchor 기반에서 Anchor-free 및분산이동성제어 Access network 별상이한이동성제어에서 Access agnostic 이동성제어 PDN 및베어러기반이동성제어에서 IP Flow 이동성제어단순정적이동성제어에서응용인식및동적이동성제어 IP routing Tunneling IP routing (new session) RO (on going session) Tunneling Centralized & Anchored MM Distributed & Anchor-free MM P-GW MME S-GW euce CGW 4G RAN WiFi RAN 5G RAN WiFi RAN Access dependent MM 4G 이동제어 Access agnostic MM 5G 이동제어
22 Tech. Issues - Signaling Common Access 특성에독립적인공통시그널링체계 Access 구간내의기존시그널링수정필요성고민 Module 화 CM/SM/MM 분리 다양한특성의단말군에유연하게적용 가상화환경의효율적인적용가능성확보 On-Demand FFS 2G~4G 2G~4G NAS 2G~4G NAS NAS 2~4 G RAN UE 2~4 G RAN Relay 2~4G BS 2G~4G 2G~4G NAS 2G~4G NAS NAS 2~4G CN 액세스네트워크종속적인 NAS 구조 액세스네트워크독립적인 NAS 구조 Access Independent Common NAS + S1-MME-like UE 5G Specific WiF Specific 5G RAN WiFi RAN AI NAS UCE
Standardization (ITU-T) ITU-T FG on IMT-2020 5G 의주요이슈를분석하고 SG13 에표준화필요한아이템발굴 (Gap Analysis) 및보고 IMT-2020 요구사항및 19 개의 Gap 도출 Gap Analysis: 5G 시대에도래될새로운서비스요구사항대비현재기술또는표준이제공하지못하는부분에대한분석 High-level network architecture 23
Standardization (3GPP) 5G 요구사항및구조에대한 Study Item 진행중 SMARTER(Study on New Services and Markets Technology Enablers, TR 22.891) 15년 3월시작하여 15년 11월에 1차완료 5G Architecture (Study on Architecture for Next Generation, TR 23.799) 표준개발일정 : 15년 10월 ~ 16년 8월 Overall Architecture, Session Management, QoS Framework 등중점참여 NexGen 주요 Key Issue 와 ETRI 의방향성비교 Key Issue Title 3GPP TR23.799 (NexGen) Key Issue 설명 ETRI 방향성 Minimizing access dependencies 및 Session Management QoS Framework Mobility Framework 이기종인터페이스수용이용이하도록하기위한코어네트워크의접속네트워크의존성을최소화하기위한솔루션논의 세션관리의효율화와더불어 QoS 제어를최적화하기위한솔루션논의 이동에따른경로비효율화를개선하고자하는솔루션논의 융합접속및세션제어 는 WiFi, 유선망을포함하여이기종인터페이스의수용이용이하도록하기위한공통시그널링체계의구축을목표로하며 NexGen 의접속네트워크의존성을최소화 기존의베어러설정및그에기반한복잡한 QoS 제어를단순화하며플로우기반의 QoS 를 Anchor-free 이동성제공기술을통해기존솔루션에서트래픽의집중의이슈및비효율적인경로의개선 24