Tran Minh Trung

Ph.D., Hanoi University of Science and Technology – School of Electronics and Communications

Archive for the ‘Working papers’ Category

Protected: A distributed TDMA Multi-Channel MAC protocol for multimedia traffic over Mesh networks

Posted by trungtm on August 15, 2007

  1. Over view

    • Challenges
      • Delay over multi-hops
      • Low payload to overhead ratio for short VoIP
    • Research objectives
      • Support QoS for multimedia traffic (Video/Voice) traffic between Mesh routers
      • Reduce delay over multi-hop
      • Increase payload to overhead ratio
    • Solution approaches
      • TDMA based MAC protocol
      • Multi-channel & Multi-Interface
  2. Mesh back bone architecture

    • Mesh component
      • Mesh internet gate way (A,B), Mesh router (access point), Mesh client (Mobile, laptop, PDA)
      • Long distance communication (kms)
      • Low mesh router density
    • Mesh router configuration
      • A mesh router has 1 or more than 2 radios
      • Each radio can works on multiple channels
  3. Channel & time slots assignment

    • Time is divided in to time slots
      • Each multimedia link is allocated to a specific channel and time slots
      • Mesh router belong to multiples domain have to works on different channels
    • Mesh routers are grouped into collision domains.
      • Adjacent collision domains use different channel to better utilize channel resources
    • Time is divided in to time slots
      • Each multimedia link is allocated to a specific channel and time slots
      • Mesh router belong to multiples domain have to works on different channels
    • 2 sub-graph problems
      • Fill different color (channel) to adjacent area (collision domain)
        • Use the four color theorem
      • Assign different color (time slots) to edge in one – easy
        • Use the edge coloring

(Will be revised and updated)

Posted in Working papers | Leave a Comment »

WiFlex: Multi-Channel Cooperative MAC protocol for Heterogeneous Wireless Devices

Posted by trungtm on June 16, 2007

Incompatible wireless protocols in the ISM band are proliferating, creating increasingly complex co-existence problems. This paper proposes a family of compatible protocols that address the requirements of a wide range of devices, from small sensor nodes to media centers. The family is based on an OFDM physical layer and on a distributed multi-channel asynchronous MAC protocol that supports priorities and radios that can modulate different amounts of bandwidth. The MAC protocol is shown to be collision-free. The performance of the protocols is evaluated using a multichannel extension of NS-2 that also models capture effects. The evaluation results demonstrate the high performance of theprotocols and the coexistence of devices with different characteristics and of applications with different requirements.

Posted in Working papers | Leave a Comment »