ELASTIC- Enabling Massive-Antenna for Joint Spectrum Sensing and Sharing: How Many Antennas Do We Need?

Massive antenna and cognitive radio (CR) technologies have attracted many research interests due to the additional resources offered in striving against the spectrum crisis. In this paper, we propose a general framework to enable massive antenna exploitation for spectrum sensing and sharing in CR. Using random matrix theory and moment matching method, we derived a simple approximation of the distributions of three eigen-value-based detectors namely the largest eigenvalue (LE), the scaled LE, and standard condition number. This has led to a simple analytical formulation and optimization of the number of antennas and the number of samples to reach a target performance. To exploit the large number of antennas, we proposed two sensing scenarios. The first is based on full antenna exploitation and guarantees an optimal performance despite the transmission conditions. The second is based on partial antenna exploitation, which determines the exact number of antennas and samples required to reach the target performance. We have shown that the framework offers an additional degree of freedom in the selection of the optimal system parameters, namely the number of antennas, while the remaining antennas are exploited for sharing in other dimensions of the spectrum hypercube.