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A Cooperative Multi-Channel MAC Protocol for Wireless Networks. Devu Manikantan Shila, Tricha Anjali and Yu Cheng. Dept. of Electrical and Computer Engineering, Illinois Institute of Technology, Chicago, USA. IEEE Globecom 2010. Outline. Introduction Goals The Proposed MAC Protocol
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A Cooperative Multi-Channel MAC Protocol for Wireless Networks Devu Manikantan Shila, Tricha Anjali and Yu Cheng Dept. of Electrical and Computer Engineering, Illinois Institute of Technology, Chicago, USA IEEE Globecom 2010
Outline • Introduction • Goals • The Proposed MAC Protocol • Simulation • Conclusion
Introduction • How to provide robust communication over fading channels is a crucial challenge in wireless networks • cooperative communications achieve spatial diversity and thereby reduce the negative effects of fading on wireless channels
Introduction • Deploying cooperativerelays in large-scale wireless networks lead to : • Anelevated level of interference • Degradedthroughput • Higher packet losses • Multiple channel • mitigate the wirelessinterference
Goals • Designing a protocol • Integrate the capabilities of both cooperativecommunications and multiple channels into wireless networks
The Proposed MAC Protocol • CoopMC MAC protocol • There are C channels in the network • Each node (source, destination and relay) is equipped with two half-duplex interface • Cooperative link • Direct path • Relay path • Assume that each source node is aware of the best helper nodes
The Proposed MAC Protocol • Data Structures in CoopMC design • Each node maintains • Neighbor-table (Ntable) • Find a best helper node to assist the communication • Good Channel State Information • Minimum interfering neighbors • Channel-table (CTable) • Counter that indicates the number of neighbors that have planned to utilize the channel
The Proposed MAC Protocol • Based on the existing Multichannel MAC protocol (MMAC) • Control phase • Pre-defined channel • Data phase
The Proposed MAC Protocol • Channel negotiation during the Control Phase • If the channel is busy • Sender should wait until the channel is idle plus a DIFS time period Relay Sender Destination 1. Carry sense
The Proposed MAC Protocol • Channel negotiation during the Control Phase • If the channel is idle for a DIFS time period and has completed the required backoff process Relay Sender Destination 2. send CTU(CTable)
The Proposed MAC Protocol • Channel negotiation during the Control Phase • A helper node cannot cooperate • Channel is busy due to other transmissions • Helper node has already agreed to serve another transmission 3. send CTU-R(CTable) Relay Sender Destination
The Proposed MAC Protocol • Channel negotiation during the Control Phase • Destinationselects two channels based on the CTables at sender, relay and itself 2 Relay 1 Sender Destination 4. send CTU-ACK(1,2)
The Proposed MAC Protocol • Channel negotiation during the Control Phase • Destinationselects two channels based on the CTables at sender, relay and itself 1 2 1 2 Relay 1 Sender Destination 4. send CTU-ACK(1,2)
The Proposed MAC Protocol • Channel negotiation during the Control Phase 2 Relay 1 Sender Destination 5. send CTU-RES(1)
The Proposed MAC Protocol • Channel negotiation during the Control Phase • If the CTUR-RES packet is not heard, the senderand destinationswitch to direct transmission mode in the DATA Phase 6. send CTUR-RES(1,2) 2 Relay 1 Sender Destination 5. send CTU-RES(1)
Example • Control phase
Example Relay • Data phase 1 2 Sender Destination 1 Channel 2
Simulation • NS-2 simulator • A grid of 40 wireless nodes located in 1000x1000(m) • Bit rate of channel is 2Mbps • Transmission range of each node is 250m • Randomly select the source and destination pairs • Traffic flow adopted UDP/CBR
Simulation • Assume that sufficient number of relay nodes are present in the network • Packet size is 1000 bytes. • The beacon interval is set to 150ms and control phase duration as 32ms
Simulation • Aggregate Throughput vs. Packet Arrival Rate
Simulation • Sensitivity of models to wireless errors
Simulation • Impact of Channels on Throughput
Conclusion • The auther proposed a cooperative multi-channel (CoopMC) MAC protocol • Allocates each cooperative transmission, dynamically, onto a different channel. • The simulation results • Greatly reduce the interference in cooperative wireless network • Provide an enhanced performance