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Topology Control of Multihop Wireless Networks using Transmit

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Topology Control of Multihop Wireless Networks using Transmit Powered By Docstoc
					       Topology Control of Multihop Wireless Networks
             using Transmit Power Adjustment

                        INFOCOM 2000

              Ram Ramanathan, Regina Rosales-Hain


                                        Bae Chi-Sung
                                        Jan. 20, 2005
                                Network Systems Lab.



                                                         KAIST
No.1                                        Network Systems Lab.
Outline
 Introduction
 Problem formulation
 Centralized Algorithms
    Connected Min-Max Power (CMP)
    Bi-Connectivity Augmentation with Min-Max Power
 Distributed Heuristic Algorithms
    LINT (Local Information No Topology)
    LILT (Local Information Link-state Topology)
 Simulation Result
 Summary
 Critique




                                                             KAIST
No.2                                            Network Systems Lab.
Introduction
 Topology
       The set of communication links between node pairs used by routing
       mechanism
         Uncontrollable factor: Mobility, Weather, Interference, Noise
         Controllable factor: Transmit power, Antenna direction.

 Drawback of Wrong Topology
        Reduce the capacity
        Increase interference
        Increase end-to-end packet delay
        Decrease the robustness to node failure

 Consider transmit power adjustment problem in a multi-
  hop wireless network to create a desired topology
                                                                   KAIST
No.3                                                  Network Systems Lab.
Topology Control




                                KAIST
No.4               Network Systems Lab.
K-vertex/edge-connected
A graph is k-vertex/edge-connected if and only if
 there are k vertex/edge-disjoint paths between
 every pair of vertices




       (a)1-vertex/edge-connected   (b) 2-vertex/edge-connected
       (connected)                  (bi-connected)     KAIST
No.5                                          Network Systems Lab.
Problem formulation
 Connected Min-Max power
        Given an M=(N, L)
                                                                         
        Find a per-node minimal assignment of transmit powers p : N  Z
         such that (1) the induced graph of (M,  ,p) is connected
                   (2) MAX uN ( p(u )) is minimum.


 Bi-connectivity Augmentation with Min-Max Power
        Given M=(N,L), and initial transmit power p : N  Z  such that
         the induced graph (M,  , p) is connected
        Find a per node minimal set of power increases  (u)
         such that (1) induced graph of (M,  , p(u )   (u )) is bi-connected
                   (2) MAX uN ( p(u )   (u )) is minimum


                                                                       KAIST
No.6                                                      Network Systems Lab.
Algorithm CONNECT
Input: (1) Multi-hop wireless network M= (N, L)
      (2) Least-power function
Output: Power levels for each node that induces
        a connected graph

Begin
1. Sort node pairs in non-decreasing order of
    mutual distance
2. initialize |N| clusters, one per node
3. for each (u,v) in sorted order do
4. if cluster(u)cluster(v)
5.          p(u)=p(v)=(d(u,v))
6.          merge cluster(u) with cluster(v)
7.          if number of cluster is 1
            then end
8. perNodeMinimalize(M,,p,1)
end
                                                               KAIST
No.7                                              Network Systems Lab.
Per Node Minimize

  Procedure perNodeMinimalize(M,,p,k)
  Begin
  1. let S = sorted node pair list
  2. for each node u do
  3. T={(n1,n2)S: u=n1 or u=n2}
  4. sort T in no-increasing order of distance
  5. discard from T all (x, y) such that
      (d(x,y))>p(u)
  6. for (x, y)  T using binary search do
  7. if graph with p(u)=(d(x,y)) is not k-
      connected, Stop
  8. else p(u)= (d(x,y)
  end



                                                              KAIST
No.8                                             Network Systems Lab.
Algorithm BICONN-AUGMENT
Input: (1) Multi-hop wireless network M= (N, L)
       (2) Least-power function
       (3) Initial power assignment inducing connected network
Output: Power levels for each node that induces a bi-connected graph.

Begin
1. sort node pairs in non-decreasing order of distance
2. G=graph induced by (M,,p)
3. For each (u,v) in sorted order do
4. if biconn-comp(G,u) biconn-comp(G,v)
5.       q= (d(u,v))
6.       p(u)=max(q,p(u))
7.       q(u)=max(q,p(v))
8.       add (u,v) to G
9. perNodeMinimalize(M,, p, 2)
end
                                                                  KAIST
No.9                                                 Network Systems Lab.
 Example




  (a) Connected Networks   (b) Bi-connected Networks (c) Without Topology Control




                                                                       KAIST
No.10                                                     Network Systems Lab.
Local Information No Topology Algorithm (LINT)

 Use locally available neighbor propagation model
  information                     (r )   (rthr ) if r  rthr

 Attempts to keep the degree  (r )   (rthr )  10 log( r ), if r  rthr
                                                                rthr
  of each node
        If node degree > dh
           reduces transmit power        d c  D rc 2
        If node degree < dl              d d  D rd2
           increases transmit power                                     rc
                                          pc  ( (rthr )  10 log(        ))  T
                                                                       rthr
 Power update equation                   pd  ( (rthr )  10 log(
                                                                        rd
                                                                            ))  T
                            dd
        pd  pc  5 log(      )                                       rthr
                            dc                                dd
                                          pd  pc  5 log(      )
                                                              dc
                                                                         KAIST
No.11                                                      Network Systems Lab.
 Local Information Link-state Topology Algorithm (LILT)

  Uses freely available neighbor information and global
   topology information
  Triggered whenever an event driven or periodic link-state
   update
  A node determine topology states and take following
   action
         Bi-connected
           No Action
         Connected but not Bi-connected
           1. Finds its distance form the closest articulation point
           2. Set a timer for a value t
           3. If acter time t the network is still not bi-connected, the node
              increase its power to the maximum possible.
         Disconnected
           Increases its transmit power to maximum possible value
                                                                      KAIST
No.12                                                    Network Systems Lab.
 Experiment Environment
  40 node network, 3 minutes simulation time
  Use link-state routing mechanism
  Radio and its emulation
         Use Utilicom Logranger 2020
         900MHz ISM band (raw data rate 300Kbps)
         Transmission range: 6Miles
         Use software emulation of radio and its MAC layer Protocol
  Mobility and Propagation model
         Mobility: pseudo-random mobility model (72miles/hour)
                                                               h1
         Propagation model:   (d )  156  40log(d )  15log( )  ( g1  g 2)
                                                               h2
  12 data stream (random chosen source-destination pair,
   mean rate is 4kbps)

                                                                                KAIST
No.13                                                              Network Systems Lab.
 Simulation Result (static networks)
                      For grater than 1.5nodes/sq,
                       interference reduces spatial
                       reuse
                      BICONN gives the best
                       throughput and adapt well to
                       changing density




                      BICONN uses significantly more
                       power than CONNECT

                                               KAIST
No.14                             Network Systems Lab.
 Simulation Result (mobile networks)
                     Above a density of 1 node/sq mile
                      increased density causes a decrease in
                      throughput
                     Both LINT and LILT appropriately
                      reduce interference and improve
                      throughput
                     LINT does better than LILT




                     Only slight gains in delay performance




                                                  KAIST
No.15                                Network Systems Lab.
 Concluding remarks
  Propose Centralized algorithms and distributed heuristics
   for transmit power control
  Relevant to Commercial
  Static network algorithms improve the throughput and
   battery life of infrequently mobile instant infrastructure
   networks (Metricom’s Ricochet networks)




                                                          KAIST
No.16                                        Network Systems Lab.

				
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posted:8/25/2011
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