Closed-form capacity formula for multi-antenna cognitive radio networks with asymmetric fading

Abstract

A cognitive radio network with a multiple-input single-output secondary link and a multi-antenna primary receiver is considered. The secondary transmitter steers its transmission into the direction of its intended destination in order to maximize the received signal-to-noise ratio. Under this beam-forming strategy, the power allocation is optimized to achieve the ergodic capacity under the constraint that the long-term interference, caused at the primary receiver, will not exceed a predefined threshold. Assuming line-of-sight communication (Rician fading) for the secondary link and Rayleigh fading for the secondary-to-primary link channel, we derive the exact closed-form expression for the ergodic capacity. Numerical results corroborate theoretical findings and illustrate the manifold impact of the system parameters into its performance.<p>QC 20150211</p

Closed-Form Capacity Result for Interference-Limited Environments With Mixed Fading

“…In this paper, we generalize the original study [15] and refine some of the results presented therein. We expand the scope of the network model, studied in [15], to address general cellular networks with clusters of neighboring-cell edge-users, see Fig.…”

“…(15). Due to the presence of the Gaussian tail function, the resulting integrals are not amenable to the manipulations that facilitated reshaping of the infinite series into finite, as in Eqs.…”

“…We emphasize an insightful mathematical result, i.e., how the F -distribution arises in the stochastic characterization of the network, because of its gravity in analytical derivations that were previously inhibited without this observation [12]. Moreover, we introduce a mathematical technique that allows us to reshape a certain class of infinite series into a finite one and we utilize it to further enhance [15,Eqs. (2), (3)], which are in the form of infinite series and whose numerical evaluation can only be approximate, since one has to truncate the series and characterize the behavior of the truncation error.…”

“…Characterization of statistics, pertaining to LoS fading, was provided in [14] though the setup, considered therein, addressed the single-antenna case and it was not motivated by a practical scenario. This is settled in [15] where characterization of the link ergodic capacity, with transmit beamfoming and optimized power allocation, was presented. The authors exploited the choice of channel model and identified the F -distribution [16], [17] in order to obtain closed-form results for the ergodic capacity under interference power constraints.…”

“…We expand the scope of the network model, studied in [15], to address general cellular networks with clusters of neighboring-cell edge-users, see Fig. 1, that are protected, by means of an ergodic sum-interference power constraint (ESIPC), from an active link between a multi-antenna base station and its associated receiver (TR link).…”