Goodput and power performance of the spatial cognitive technique

Cognitive radio (CR) and Multiple Input Multiple Output (MIMO) technologies represent emerging and promising technologies for providing high spectrum utilization, and maximizing the capacity to face the huge demand for wireless applications. In this context, a transmission scheme that exploits both CR and MIMO is presented, together with its optimization to increase the system goodput as well as to decrease the total power consumption. In this paper we present and investigate this Spatial Cognitive Technique through a Zero-Forcing BeamForming (ZFB) as well as Adaptive Modulation, where a predefined Quality of Service (QoS) is guaranteed for Primary Users (PU), while Secondary Users (SU) are serviced as long as they do not compromise the QoS to the PU. The QoS is denoted as minimum guaranteed goodput and maximum allowed Symbol Error Rate (SER) metrics. Closed form expression for the SER, goodput and total consumed power are mathematically formulated and illustrated by extensive simulations.