An Integrated Cluster-Based Multi-Channel MAC Protocol for Mobile Ad Hoc Networks

1
An Integrated Cluster-Based Multi-Channel MAC
Protocol for Mobile Ad Hoc Networks

• Lili Zhang, Boon-Hee Soong, Wendong Xiao
• IEEE Transactions on Wireless Communications
• Nov 2007
• Speaker Kun-Xing Zhou

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Outline

• Introduction
• Related Works
• ICMMP
• Simulation Result
• Conclusion

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Introduction

• In CDMA-based multi-channel MAC protocol
• The same codes can only be reused more than two
  hops away to avoid HTP.
• Need complete neighborhood information.
• Code broadcasting will suffer collision.
• Exchange information incurs a heavy control
  overhead.

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Related Works

• CDMA-Based Multi-Channel MAC Protocols.
• Access Based Clustering Algorithms.

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Outline

• Introduction
• Related Works
• ICMMP
• Simulation Result
• Conclusion

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Two-Phase Coding Scheme

• Divide a set of orthogonal codes into sub-sets.
• First-Phase Code
• Differentiate the adjacent clusters.
• Sequence number of the sub-sets.
• Second-Phase Code
• Distinguish nodes in a specific cluster.
• Sequence number of the codes in one set-set.

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Code Confliction

• Two nodes within two-hop separation adopt the
  same transmission code.
• Collision may happen at their common neighbors.

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Criteria for Code Assignment

• Nodes in the same cluster can not be assigned the
  same second-phase code.
• Two neighboring clusters can not be assigned the
  same first-phase code.
• When two clusters has common neighbor, they can
  not be assigned the same first-phase code.

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Protocol Operation Mechanism

• CH is responsible for maintaining and assigning
  second-phase codes to its CMs.
• CM is one hop away from its CH.
• Divide wireless channel into control channel and
  data channel.
• Network is synchronized.

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Initial Clustering Algorithm
Initial
Doesnt hear any broadcast
Defer a random time
Receive Broadcast
Broadcast to claim itself as a CH
Become a member of the cluster
CH
CM
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Access Format of Control Channel (1/2)
RFS Request for Slot COS Confirmation of
Slot MS Maintenance Slot
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Access Format of Control Channel (2/2)

• Each frame is related to a first-phase code, so
  adjacent clusters use different frame.
• Clusters that are spatially separate enough can
  use the same frame.
• Each CM in a cluster use a unique MS of a frame.

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Selection of The First-Phase Codes (1/3)

• Each CM keeps a table that records neighboring
  clusters first-phase code.
• A CH waits a new free frame, and send the
  presumed first-phase code in the BS.
• The CMs that receive the message will check its
  table to see if confliction occurs.
• The CMs report it by sending broadcasting
  messages.

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Selection of The First-Phase Codes (2/3)

• The table is updated by the broadcast message of
  CMs of neighbor clusters.
• If CH doesnt receive any opposition messages, it
  will broadcast beacon message periodically.
• The CMs will record the first-phase code in the
  beacon message, and broadcast to neighbor
  cluster.

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Selection of The First-Phase Codes (3/3)

• If a CH detect its neighbors has the same
  first-phase code, it will use a method to adjust.
• Keep the first-phase code of a cluster which has
  more node, and the cluster that has less node
  must re-obtain its code.

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Selection of The Second-Phase Code (1/3)

• CMs will contend to obtain their MS.
• If any nodes RFS message suffer collision, it
  will decide with ½ probability whether it will
  transmit RFS in next MS.
• If there doesnt have any collision, the CM will
  receive COS from CH.
• New CMs will listen the beacon message before
  participating the contention.

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Selection of The Second-Phase Code (2/3)
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Selection of The Second-Phase Code (3/3)

• A CM which has its MS can request its
  second-phase code by sending RFS without
  contention.
• CH responses the code by COS.
• CM acknowledges its CH by sending broadcasting
  message.
• The broadcasting message will also send the code
  information to destination node.

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Data Transmission

• After getting the transmission code, the
  transmission will be initiated immediately in the
  data channel.
• After the transmission finishes, the CM will
  return the second-phase code to CH by
  broadcasting message.

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Outline

• Introduction
• Related Works
• ICMMP
• Simulation Result
• Conclusion

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Control Overhead vs. Transmission range
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Control Overhead vs. Average Speed
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Average Delay of Code Acquisition vs.
Transmission Range
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Outline

• Introduction
• Related Works
• ICMMP
• Simulation Result
• Conclusion

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Conclusion

• Dividing code into subsets is a good idea.
• ICMMP protocol improve the performance by
  reducing the control overhead.
• By detection and resolution of cold confliction,
  ICMMP can combat the Hidden Terminal Problem
  during data transmission.