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XORS IN THE AIR: PRACTICAL WIRELESS NETWORK CODING

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This paper proposes COPE, a new architecture for wireless mesh networks ... COPE is run as a bundle layer between MAC layer and network layer ... – PowerPoint PPT presentation

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Title: XORS IN THE AIR: PRACTICAL WIRELESS NETWORK CODING


1
XORS IN THE AIR PRACTICAL WIRELESS NETWORK CODING
  • Athours
  • Sachin Katti Hariharan Rahul Wenjun Hu?
    Dina Katabi Muriel Medard Jon Crowcroft?
  • MIT CSAIL ?Univ. of Cambridge

SIGCOMM06
2
OUTLINE
  • Motivation
  • Methodology - COPE
  • Opportunistic Coding
  • Understanding COPSs gains
  • Coding MAC gain
  • Experimental Results
  • Pros and Cons

3
MOTIVATION
  • This paper proposes COPE, a new architecture for
    wireless mesh networks
  • In addition to forwarding packets, routers code
    packets from different sources to increase the
    information content of each transmission
  • COPE is run as a bundle layer between MAC layer
    and network layer
  • This paper implements COPE on WiFi 802.11

4
MOTIVATION
5
MOTIVATION
  • P1 01001 P2 10011
  • gt P3 P1 xor P2 11010
  • Alice P3 xor P1 10011 P2
  • Bob P3 xor P2 01001 P1

6
METHODOLOGY - OPPORTUNISTIC CODING
7
METHODOLOGY - UNDERSTANDING COPSS GAINS
  • (a) transmissions 4
  • (b) transmissions 3
  • gt Coding gain 4/3 1.33

8
METHODOLOGY - CODING MAC GAIN
  • Assuming all nodes continuously have traffic to
    send
  • Because it tries to be fair, the MAC divides the
    bandwidth equally between the 3 contending nodes
    Alice, Bob, and the router.

1.5K
3K
3K
1.5K
9
METHODOLOGY - CODING MAC GAIN
  • Assuming all nodes continuously have traffic to
    send
  • Because it tries to be fair, the MAC divides the
    bandwidth equally between the 3 contending nodes
    Alice, Bob, and the router.

1.5K
Received by Alice and Bob 3K
1.5K
1.5K
1.5K
10
METHODOLOGY - CODING MAC GAIN
Received by Alice and Bob 6K
  • Coding MAC gain 6K/3K 2

3K
3K
3K
11
METHODOLOGY - GAIN
  • Theoretical gains for a few basic topologies

Chain topology
X topology
Cross topology
Wheel topology
12
EXPERIMENTAL RESULTS TEST BED
20 nodes locations for two floor of the testbed
13
EXPERIMENTAL RESULTS - COPE IN GADGET TOPOLOGIES
TCP gain in the Alice-and-Bob topology
UDP gain in the Alice-and-Bob topology
14
EXPERIMENTAL RESULTS - COPE IN GADGET TOPOLOGIES
TCP gain in the X-topology
UDP gain in the X-topology
15
EXPERIMENTAL RESULTS - COPE IN GADGET TOPOLOGIES
TCP gain in the cross topology
UDP gain in the cross topology
16
EXPERIMENTAL RESULTS TESTBED
  • COPE provides 38 increase in TCP goodput when
    the testbed topology does not contain hidden
    terminals

17
EXPERIMENTAL RESULTS TESTBED
  • COPE can provide a several-fold (3-4x) increase
    in the throughput of wireless Ad hoc networks.
    Results are for UDP flows with randomly picked
    source-destination pairs, Poisson arrivals, and
    heavytail size distribution.

18
PROS
  • COPE provides enhancement of throughput without
    too much extra coding overhead
  • COPE can not only apply on WiFi, but also other
    MAC protocols, such as WiMax, sensor networks.
  • COPE doesnt optimize power usage

CONS
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