Interference model for ad hoc DS/CDMA packet radio networks with variable coherent modulation

This paper presents a model for the multiple access interference (MAI) in an ad hoc DS/CDMA packet radio network in which multiple modulation schemes are used. One application of this model is in the performance analysis of ad hoc networks using adaptive modulation, where each node may be using a different modulation scheme depending on channel conditions or rate requirements. Previous work has shown that the MAI in a random access packet radio network can be characterized by an α-stable distribution. This model is extended to account for systems using two-dimensional constellations and is compared with simulation results to validate the model. In particular, the accuracy of the model is examined for low processing gain, and a previously used assumption of independent shadowing on different links is tested in a correlated shadowing environment.