ResearchIndex

url:

http://www.mit.edu/~mythili/research/cmap.pdf

type:

misc

abstract:

This paper presents the design, implementation, and ex- perimental evaluation of CMAP (Conflict Maps), a system that increases the number of successful concurrent trans- missions in a wireless network, achieving higher aggregate throughput compared to networks that use carrier sense multiple access (CSMA). CMAP correctly identifies and ex- ploits exposed terminals in which two senders are within range of one another, but each intended receiver is far enough from the other sender that the two transmissions can succeed even if done concurrently. CMAP includes a reac- tive channel access scheme in which nodes transmit con- currently (even if there’s the possibility of a collision), then observe the loss probability to determine whether they are better off transmitting concurrently or not. Experimental re- sults from a 50-node 802.11a testbed show that CMAP im- proves throughput by 2× over CSMA with exposed termi- nals, while converging to the performance of CSMA when the senders and receivers are all close to each other. CMAP also improves throughput by up to 47% over CSMA in real- istic access point-based networks by exploiting concurrent transmission opportunities.