SDMA with secrecy constraints

Wireless transmission requires the access to a shared medium, so the communication may be susceptible to adversarial eavesdropping. This paper describes how eavesdropping can potentially be limited by resorting to waterfilling-like algorithms by introducing additional constraints. A Gaussian Wire-Tap Channel (WTC) has been considered as the channel in which a transmitter sends confidential messages to its reference receiver in the presence of a passive eavesdropper. In the more general context of an ad-hoc network, we propose two different Space Division Multiple Access (SDMA) techniques by paying attention to the rate of the main link and to secrecy level. Through numerical analysis, we show the information-secrecy regions to evaluate the quality of main link and secrecy level that the algorithms can allow when constrained SDMA is considered. Finally, we evaluate the effect of interference (induced by users sharing the same transmission resource) to evaluate the effect of disturbing signals on information rate and secrecy.