Optimal SISO and MIMO Spectral Efficiency to Minimize Hidden-Node Network Interference

In this letter, the optimal spectral efficiency for a given message size that minimizes the probability of causing disruptive interference for ad hoc wireless networks or cognitive radios is investigated. Implicitly, the trade being optimized is between longer transmit duration and wider bandwidth versus higher transmit power. Both single-input single-output (SISO) and multiple-input multiple-output (MIMO) links are considered. Here, a link optimizes its spectral efficiency to be a "good neighbor." The probability of interference is characterized by the probability that the signal power received by a hidden node in a wireless network exceeds some threshold. The optimization is a function of the transmitter-to-hidden-node channel exponent. It is shown that for typical channel exponents a spectral efficiency of slightly greater than 1 b/s/Hz per antenna is optimal.