Fast Intra-Network and Cross-Layer Handover _FINCH_ for WiMAX

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					IEEE Transactions on Mobile Computing, vol. 8, no. 4, pp. 558-574, 2009.

              Fast Intra-Network and
           Cross-Layer Handover (FINCH)
          for WiMAX and Mobile Internet
                   J.-H. Yeh, J.-C. Chen, and P. Agrawal

•   Introduction
•   Related Work
•   Design Principles
•   Proposed FINCH
•   Performance Analysis
•   Numerical Results
•   Conclusion

• 802.16 standardizes physical (PHY) layer and Media Access Control
  (MAC) layer only.
• To build a complete system, higher layers are necessary.
   – One of the major objectives of WiMAX Forum is to promote conformance
     and interoperability of the IEEE 802.16 standards.

• The Access Service Network (ASN)
   – provides radio access to WiMAX subscribers.
   – consists of one or more ASN Gateways (ASN GWs) and Base Stations (BSs).
• ASNs are connected by Connectivity Service Network (CSN)
   – provides Internet Protocol (IP) connectivity services.

• Mobile IP (MIP, IETF RFC 3344) is adopted by WiMAX Forum.
   – The Home Agent (HA) of a Mobile Station (MS) is located in the CSN of the
     MS’s Home Network Service Provider (H-NSP).
   – ASN GW supports the Foreign Agent (FA) functionality.
       • intra-ASN mobility  no need to update MS’s care-of-address (CoA).
       • inter-ASN mobility  the MS needs to update its CoA.
• MIP is simple and effective
    – to deal with interdomain mobility management in the network layer.
• MIP’s deficiencies
    – frequent location update,
    – long handover (HO) delay, and
    – long end-to-end latency.
          • route optimization has been proposed,
                  – can result in latency, which is highly variable.
    – may not be suitable for intradomain mobility
          • especially for real-time services

• IPv6 might be more efficient than IPv4,
    – it is not widely deployed.
• this paper only focuses on the IPv4 over Ethernet-like link model [6]
    –   [6] J. Jee, S. Madanapalli, and J. Mandin, IP over IEEE 802.16 Problem Statement and Goals, IETF RFC 5154, Apr. 2008.
    – the Address Resolution Protocol (ARP) can incur significant delay for both
      packet delivery and HO

                            The proposal
• for interdomain mobility (inter-CSN mobility)
   – use MIP only.
• for intradomain mobility (intra-CSN mobility)
   – a new protocol, Fast Intra-Network and Cross-layer Handover (FINCH),
       • which can achieve fast HO, especially for real-time services.
       • paging extension is designed
            – to conserve the energy of MS and
            – reduce the signaling overhead for location update

•   Introduction
•   Related Work
•   Design Principles
•   Proposed FINCH
•   Performance Analysis
•   Numerical Results
•   Conclusion

                                      Related Work
• Interdomain
  – MobileIP, SessionInitiateProtocol, HostIdentityProtocol
• Intradomain
  – Tunnel-based
       • HierarchicalMIP
              – E. Gustafsson, A. Jonsson, and C. Perkins, “Mobile IPv4 Regional Registration,” IETF Internet draft, work in
                progress, Oct. 2006. (RFC 2007)

  – Host-specific-routing-based
       • Cellular IP
              –   A. T. Campbell, J. Gomez, S. Kim et al., “Design, implementation, and evaluation of cellular IP,” Personal Communications,
                  IEEE, vol. 7, no. 4, pp. 42-49, 2000.

       • Handoff-Aware Wireless Access Internet Infrastructure (HAWAII)
              – R. Ramjee, K. Varadhan, L. Salgarelli et al., “HAWAII: a domain-based approach for supporting mobility in wide-
                area wireless networks,” TON: IEEE/ACM Transactions on Networking, vol. 10, no. 3, pp. 396-410, 2002.
       • FINCH
  – Fast HOs for MIPv4
       •   R. Koodli, and C. Perkins, "Mobile IPv4 Fast Handovers," IETF, RFC 4988, 2007.

• Tunnel-based

                        Gateway FA


                                 Cellular IP
• intends to minimize the usage of explicit signaling messages
• a layer three routing protocol
   – identifies MS with its home address and
       • MHs use the IP address of the gateway as their MIP care-of address.
   – directly routes packets without tunneling or address conversion
   – Uplink packets
       • sent to the gateway in a hop-by-hop manner.
       • each node on the path will cache
         the source direction of the MS.
   – Downlink packets
       • be forwarded back to the MS
         with the routing caches.
   – When there is no data to send,
     MS must send a special IP packet
     toward the gateway
     to indicate its current location.
• Use MIP to handle macro-mobility (interdomain)
• Network nodes maintain mobile-specific routing entries on the
  legacy routing tables.
• MS creates, updates, and modifies the location information with
  explicit signaling messages.

• The forwarding scheme
   – buffers packets forwarded to the
     old access point and redirects them
     to the new access point.
• the nonforwarding scheme
   – drops the packets sent to the
     old access point. (?)
                  Design Principles
• Propsed Fast Intra-Network and Cross-layer Handover
  – Fast HO
  – Cross-layer
  – Scalability
     • avoid using centralized nodes
  – Paging support
  – Timely for deployment
  – Flexibility
     • not be limited to tree-based topology only

•   Introduction
•   Related Work
•   Design Principles
•   Proposed FINCH
•   Performance Analysis
•   Numerical Results
•   Conclusion

   Mobility Management in WiMAX
• when an MS leaves its home network, the HA tunnels packets
  to the MS’s current anchor ASN GW, which is essentially the FA
   – further tunnels the packets to the MS
• If the serving BS and target BS belong to different IP subnets,
  the MS needs to perform L3 HO
   – acquire an NCoA and register the NCoA with the HA

• problems
   – suboptimal problem may happen in a nontree network topology
   – most of the protocols operate on or above the IP layer.
       • They do not address link-layer mobility.
   – The broadcast-and-reply nature of ARP wastes bandwidth and causes
     extra latency
   – ARP messages may wake up the MSs in sleep/idle mode

                 Cross-layer Design
• a special table-lookup technique for both link layer and IP
  layer to update the location.
   – location updates in the link layer and IP layer are coupled
• Consequently, ARP is no longer necessary

• The mobility management and packet routing within the
  domain are done by replacing the necessary routing table
  and bridging table with a Forwarding Table (FT).

• assume that all nodes have L3 functionality
   – they are capable of processing IP packets.
• When MS 1 enters the CSN-2 domain

Handover and Location Update

• All source nodes (in the domain) know the new location of the
  MS after the location update is complete.
• The triangular routing in MIP is eliminated (Lee, “partially”)
   – no need for route optimization.

• the new path may be the one with least congestion or
  shortest path
   – the new forwarding address is updated by the first arrived frame

• Not necessary to trigger L3 HO after L2 HO is done if it is an
  across IP subnet HO.
   – The proposed scheme deals with HOs and location update and leaves
     address configuration to other protocols.
• Breaks the layer structure
   – eliminates the redundancy of doing two HOs and location
     updates in both link and IP layers.

• the FT needs to maintain a list of all terminals in the
   – Each domain does not expect to support millions or billions of
   – The table searching can also be implemented in hardware

                 Paging Extension, P-FINCH
PG: paging group
PC: paging controller

 • The proposed P-FINCH is also compatible with the mobile WiMAX standards.
 • P-FINCH can significantly reduce signaling overhead and efficiently conserve the
   energy of MSs.

 • Scalable and robust
       – paging is initiated by each PC instead of a centralized paging initiator
       – Comparing with the protocols that have only one single node to buffer packets
•   Introduction
•   Related Work
•   Design Principles
•   Proposed FINCH
•   Performance Analysis
•   Numerical Results
•   Conclusion

             Performance Analysis
•   Handover Latency and Packet Loss
•   Location Update Cost
•   Over All Cost
•   Energy Conservation

  Handover Latency and Packet Loss
• Handover latency
  – DL2 is the L2 link switching delay
  – DIP is the IP connectivity latency.
     • the duration of IP layer movement detection,
     • IP address acquisition, and configuration
  – DLU is the location update latency.
     • the latency for binding update and
     • the latency to forward packets to the new IP address.

Handover latency                        Packet loss

                   200 ms

                   200 ms

               200 ms

                             10 ms

                   200 ms      10 ms

                    200 ms      15 ms
                     Location Update Cost

•   ρ  the MS call-to-mobility ratio (CMR). defined as λ/μ,
•   U  the average cost of location update to its HA in MIP.
•   S  the cost for setting up a single link when the intradomain mobility management
    protocol sets up the path in the intradomain.
•   A  the cost of ARP operations.
•   L  the cost for setting up the direct connection between the NAR and PAR in F-MIP.   26

                           Overall Cost
• the overall cost adds up location update cost and packet
  delivery cost.

• M  the packet delivery cost of MIP.
• F  the packet forwarding/routing cost in the intradomain (or CSN).
• T  the additional re-encapsulation and decapsulation cost of MIP, F-MIP, and
• B  the cost for buffering packets at NAR in F-MIP.

Energy Conservation

•   Introduction
•   Related Work
•   Design Principles
•   Proposed FINCH
•   Performance Analysis
•   Numerical Results
•   Conclusion

Handover latency and packet loss

       Location Cost and Overall Cost


       high   mobility   low

 • when P-FINCH is applied, the cost is reduced significantly
 • When the mobility rate is low, the cost of HMIP is larger than that
   of HAWAII and MIP due to the hierarchical tunneling cost
 • the paging extension should be turned on when CMR is less than 1 33
Energy Conservation

    high   mobility   low

•   MIP is adopted as the mobility management protocol by WiMAX Forum.
     – cannot support HOs well when mobile nodes move frequently and/or when the coverage area of a
       subnet is small.
     – even exaggerated for real-time services,
          •   which require very fast HOs in mobile WiMAX networks.

•   a fast HO protocol, FINCH, for intradomain (intra-CSN) mobility management is proposed
     – discussed with examples
     – The analytical models and extensive simulations show that it can support fast and efficient link layer
       and intradomain HOs.
          •   reduces location update cost and overall cost because of the cross-layer design
•   a scalable paging extension for FINCH, P-FINCH, is proposed
     – analysis also shows that it significantly reduce the signaling overhead and energy consumption
          •   if the size of the paging area is well configured.
•   Comparing with MIP, the proposed FINCH does NOT
     – need IP encapsulation and
     – have triangular routing problem.
•   also reduces the overhead caused by registering CoA with the HA
•   the overhead and latency in interfacing conventional mobility management protocols in
    the two layers are eliminated
     – By unifying the mobility management in layer 2 and layer 3,

• Does ARP really has to propagate to the entire intra-CSN?

• The analysis is complete.


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