Analysis and Simulation Model of Physical Carrier Sensing in IEEE 802.11 Mesh Networks

In IEEE 802.11 Wireless Mesh networks, tuning of the Physical Carrier Sensing (PCS) threshold based has been shown to be an efficient way to balance the hidden vs. exposed terminal trade-off and hence improve aggregate network throughput. Clear Channel Assessment (CCA) indicates channel status by comparing the net RF energy with a suitable chosen PCS threshold to control which nodes may attempt channel access. Proper CCA implementation is critical for tuning of aggregate 802.11 network performance. However, we found that the CCA implementation in OPNET v.11 (henceforth termed as default OPNET model) has several shortcomings. These are identified with examples, and in the new model, the CCA and packet reception chain have been modified to conform better to the IEEE 802.11 specifications. The resulting new code will be made available at http:\\www.ee.washington.edu\research\funlab\pcs model .htm