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    

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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  

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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  

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SGSN   GGSN  

SGSN  

SGSN  

Architecture:  More  •  Becoming  flat  and  complicated  

– Aka:  rou?ng  •  Other  core  components  

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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  

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Cellular  vs.  Wi-­‐Fi:  More  

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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  

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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,    •  …  

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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  

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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