Outline
    • Critiques of LTE Architecture
    • CellSDN Use Cases
    • CellSDN Architecture
    • Related Work
    • Conclusion and Future Work
                                                        2
         LTE Data plane is too centralized
     • Data plane is too centralized                       •  UE: user 
                                                              equipment
                        eNodeB 1                           •  eNodeB: base 
                                                              station
                              Cellular Core Network        •  S-GW: serving 
                                                              gateway
                                                           •  P-GW: packet data 
                                     Scalability challenges at P-GW on 
                eNodeB 2                                      network gateway
                                     charging and policy enforcement!
                             S-GW 1
      UE 1
                                               P-GW     Internet and
                eNodeB 3     S-GW 2
                                                        Other IP Networks
     UE 2
                         GTP Tunnels
                                                                           3
      LTE Control plane is too distributed
     • No clear separation of control plane and data plane
              Control Plane         Home                 •  Problem with Inter-
              Data Plane           Subscriber               technology (e.g. 3G to 
                                    Server                  LTE) handof
                                    (HSS)                •  Problem of inefficient 
                                                            radio resource 
                   Mobility            Policy Control and   allocation 
                  Management             Charging Rules 
                 Entity (MME)           Function (PCRF)
      User                                             Packet Data 
                        Base           Serving         Packet Data 
                        Base           Serving           Network 
   Equipment               
      (UE)             Station        Gateway            Gateway 
                      (eNodeB)         (S-GW)            (P-GW)            4
       Advantages of SDN for Cellular Networks
     • Advantage of logically centralized control plane
        –Flexible support of middleboxes
        –Better inter-cell interference management 
        –Scalable distributed enforcement of QoS and firewall policies in 
          data plane
        –Flexible support of virtual operators by partitioning flow space
     • Advantage of common control protocol
        –Seamless subscriber mobility across technologies
     • Advantage of SDN switch
        –Traffic counters enable easy monitoring for network control and 
          billing
                                                                           5
             Flexible Middlebox Support
      • SDN provides fine grained packet classification and 
         flexible routing
                        eNodeB 1 
                               •  Easy to control flow to middleboxes for 
                                  content adaptation, echo cancellation, etc
                               •  Reduce traffic to middleboxes
                eNodeB 2            Middlebox
      UE 1
                                          SDN Switch
                eNodeB 3                                Internet and
                                                        Other IP Networks
     UE 2
                         Path setup for UE 
                         by SDN controller                                6