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Cellular Networks: Overview
CSE5469
Chunyi Peng
Agenda • Cellular Networks Architecture
• Cellular Networks vs. WiFi
• Emerging topics
Chunyi Peng (OSU) 2
Cellular Networks • To date, the only opera?onal large-‐scale wireless network with wide-‐area coverage and mobility support
Chunyi Peng (OSU) 3
Key Services: Connec?vity and More
• Pervasive connec?vity: anyone, any?me, anywhere – Device -‐> Base sta?on -‐> Cellular core Network -‐> External network or internal devices)
• Carrier-‐network services: data, voice, messaging, …
• Two salient features – Wide-‐area (e.g. na?onwide) coverage: cells – Mobility support: seamless service as we go
Chunyi Peng (OSU) 4
Cellular Network Architecture: A Simple 3G/4G Example
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3G Gateways 3G Base stations
Mobile Switching Center
Circuit Switching (CS)
Packet Switching (PS)
3G (PS + CS)
Mobility Management Entity
4G (PS only)
4G Gateways
Cellular Network Architecture • Radio access network
– Full coverage via deploying a large # of RANs • Core Network
– Data-‐plane: connec?vity and data/voice/etc transfer – Control-‐plane, management-‐plane: control and management to facilitate the data-‐plane transfer
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Core Network (3G) Radio Access Network
MSC GMSC
SGSN GGSN Chunyi Peng (OSU)
Architecture: More • Hierarchical geographic coverage
– Cell, Loca?on Area (Rou?ng Area) – Good for mobility support: loca?on update, handoff
Chunyi Peng (OSU) 7
SGSN GGSN
SGSN
SGSN
Architecture: More • Becoming flat and complicated
– Aka: rou?ng • Other core components
Chunyi Peng (OSU) 8
SGSN GGSN
SGSN
SGSN
GGSN
HSS VLR/HLR
Charging & Billing
Middle-‐box
IMS … …
Cellular vs. Wi-‐Fi
Cellular • Access network
– BS-‐ CellularCore-‐ IP backbone • Within Cellular
– Cellular-‐specific design: 3GPP standards
Wi-‐Fi • Access network
– AP to IP backbone • Wireless access
– 802.11* MAC: IEEE standards – Directly support IP/TCP
internet protocol stack (IETF)s
Chunyi Peng (OSU) 9
Cellular vs. Wi-‐Fi: More
Chunyi Peng (OSU) 10
Cellular networks: base sta4ons + core gateway
Internet: wireless access network + IP router
1.Radio Access
1A. PHY: LTE/UMTS/ …(OFDM/CDMA) 1B. MAC: schedule-‐based 1C. Radio resource control: extra control& state
1A. PHY: 802.11a/b/g/n/ac (TDMA, OFDM) 1B. MAC: CSMA-‐CA (conten?on-‐based)
2. From Access to Core Gateway
2A. Within one network 2B. Integrated (e.g., layer-‐2 tunneling from base sta?on to core switch) 2C. Control plane 2D. Support circui4ng-‐swi4ng and packet-‐switching
2A. Independent 2B. data forwarding over IP 2C. Simple control (rou?ng) 2D. packet-‐switching only
3. MISC 3A: mobility: Handoff 3A: No mobility support (default)
Mobile Network Evolu?on
Chunyi Peng (OSU) 11
1G AMPS, NMT,
TACS
1980s
analog voice
2G GSM/GPRS/EDGE
cdmaOne
1990s
Digital voice + Simple data
3G WCDMA/HSPA+ CDMA2000/EVDO
TD-‐SCDMA
2000s
Mobile broadband
APP
4G LTE
LTE-‐advanced
2010s
More and Faster
Telecom Legacy • “Smart Core Dumb End”
– Complex func?ons at the core (network infrastructure)
– Internet: “smart end dumb core”
• Circuit-‐switching for voice and Packet-‐switching for data – Two service models – Impact on architecture, protocol, func?ons/modules
– Applicable: 2G/3G Chunyi Peng (OSU) 12
Evolu?on toward IP-‐based Internet • 4G LTE
– PS only (no CS) – all-‐IP (flaier)
• 5G: next genera?on mobile network (~2020) – Unified framework – Heterogeneous RAN and virtualized access – Core network -‐> cloud (Network Func?on Virtualiza?on)
– Toward a somware solu?on Chunyi Peng (OSU) 13
Research Topics Not an exhaus?ve list On architecture perspec?ve • Radio access and radio resource control (RRC)
– Different from Wi-‐Fi – Efficiency, impact on upper layer, energy efficiency, etc
• Core network – Component study: Middlebox, DNS, Charging, IMS etc
– Next-‐genera?on architecture Chunyi Peng (OSU) 14
Research Topics (cont’d) On System concerns: performance, reliability, security • Protocol performance and user experience
– Different underlying protocols – Impact on TCP, Web, Video and other apps – Op?miza?on: caching and new protocols
• Reliability: protocol verifica?on, fault tolerance
• Security: Aiacks and countermeasures Chunyi Peng (OSU) 15
Research Topics (cont’d) On unique features • Mobility support
– How? Handoff and other mechanisms – Impacts on apps, implica?on
• Cellular + WiFi – Offloading: how to dynamically select access – MPTCP: concurrent connec?vity
• Voice support, • …
Chunyi Peng (OSU) 16
Research Topics (cont’d) On evolua?on • Evolu?on impacts: power and peril
– New features and update – Performance, reliability and security implica?ons – Compa?bility and side-‐effects
• Next-‐genera?on cellular networks – LTE-‐Advanced and 5G technologies: HetNet, Massive MIMO, Device-‐to-‐device communica?on, carrier aggrega?on, RAN Clouds, NFV, SDN, etc
Chunyi Peng (OSU) 17
Topics Covered in this seminar • Peril of the evolu?on (focus on security)
– Mobile data charging: from voice to data – VoLTE and CSFB: new voice models
• Classic problems – RRC (radio resource control) – QoS and user experience – Mobility support and HetNet (incl. WiFi + Cellular) – 5G and SDN
• Non-‐cellular topics (misc) – Relevant to mobile and wireless systems Chunyi Peng (OSU) 18