Modeling the performance of CSMA-CA based wireless networks versus interference level

Wireless communication networks based on non-scheduled random medium access methods, such as carrier sense multiple access with collision avoidance (CSMA/CA), can be affected by inchannel interference at two different levels: at physical (PHY) layer, in terms of data packet collisions, and at medium access control (MAC) layer, in terms of channel occupation. The separate knowledge of such interference effects may represent an essential information to be used in a design or setup stage of CSMA/CA–based wireless networks. To this aim, a simple yet effective two-layer model is proposed in the paper. The model allows to clearly distinguish the effect of both interference contributions and to forecast the network performance in terms of packet error ratio, in the presence of interference. An example of how to use the model, and results from experiments, validating the model, are both reported. The experiments have been conducted through a suitable testbed enlisting a IEEE 802.15.4-compliant wireless sensor network.