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Cross-layer Resource Management and Optimization in Wireless


									Cross-layer Resource Management and
        Optimization in Wireless
          Multihop Networks
                     Hao Zhu, Ph.D
                  Assistant Professor
     School of Computer and Information Sciences
            Florida International University
 Wireless multihop network and it’s
 The importance of resource
 Why do we need cross-layer
 The research of FIU team
 Conclusion
        Wireless Multihop Network
 Node Types                         Link Types
Wireless routers               Intra-mesh wireless
                            Stationary client access

Printers, servers
                                Mobile client access

Mobile clients

Stationary clients
                              Internet access links
Different Type of Links
 Wired
   Bus (PCI, PCMCIA, USB)
   Ethernet, Firewire, etc.
 Wireless
   802.11x
   Bluetooth
   Proprietary
 Point-to-Point
 Point-to-Multipoint
 Banwidth:
   From tens of Kbps to tens of Mbps
   How it Works
 User-Internet Data
   In most applications the
    main data flows

 User-User Data Flows
   In most applications a small
    percentage of data flows
Applications and Benefits
 Applications
     Broadband Internet Access
     Extend WLAN Coverage
     Mobile Internet Access
     Emergency Response
     Military Communications
     Community Networks
     Intelligent Transportation System
     Multimedia Home Networking
     ….
 Benefits
     Simple, Fast installation
     Low Power Consumption
     Low Cost
     Rich Diversity (space, frequency, bandwidth…)
Importance of Resource Management

                                                          TCP DATA
                                     A                B                             GW

                                                           TCP ACK

                    5000   RTS/CTS Disabled                                        5000   RTS/CTS Enabled
                                     Achievable TCP                                                  Achievable TCP
                    4000             Throughput                                    4000              Throughput
Throughput (kbps)

                                                               Throughput (kbps)
                                     TCP Throughput                                                  TCP Throughput
                                     (Contention)                                                    (Contention)
                    3000                                                           3000

                    2000                                                           2000

                    1000                                                           1000

                       0                                                              0

                           B->GW          A->GW                                           B->GW          A->GW
                                   Flow                                                           Flow

                              The two-hop node “starves” when contending
                              with the one-hop node
Why do we need cross-layer
 A central problem: How to efficiently transmit
  heterogeneous traffic over wireless links?
 Physical-layer limits of wireless channel:
  o time-varying fading, multipath, …
  o co-channel interference, hostile jamming, …
  o mobility, dynamic network topology, …
 Wireless networking:
  o Applications: wireless Internet access, (tactical) ad hoc
    networks, sensor networks
  o Diverse requirements: high-bandwidth video and data, low-
    bandwidth voice and data
  o Goal: reliable and quality end-to-end data delivery in highly
    dynamic environments
  Why do we need cross-layer
  optimization (cont.)
 o There exists direct coupling between physical layer
   and upper protocol layers
 o E.g. Channel competition is related to channel
   condition (layer 1), access schedule (layer 2) and
   traffic demand (layer 3 and up)
How: Adaptive protocol design
 o Which layers should respond to channel variations?
 o What layers should be jointly optimized/designed?
 o Complexity and scalability: cross-layer versus
   layered module
Research from FIU Team
 Cooperative Wireless Networking
   Cooperative MAC: explore multi-rate capability from
    the PHY layer
   High performance wireless network coding: explore
    spatial diversity to alleviate the bottleneck of
    network coding
 Self-organized Random Medium Access Control
   Optimize the network-wide bandwidth allocation with
   distributed nonlinear programming
 Cross-layer and Adaptive Routing Design
   Adjust traffic demands according to the dynamics of
    MAC and PHY layers
   Reverse-engineering the routing protocol to design
    the interaction mechanism between different layers
 Wireless Multihop Network will be a strong
  candidate for many applications due to various
 Resource management remains a challenging
  R&D issue to establish strong foundation for
  developing such new infrastructure
 Research focus: theory, algorithm, simulation,
  empirical study, business model

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