Outage Probability Analysis of Spectrum Sharing Systems With Distributed Cyclic Delay Diversity

In this paper, a distributed cognitive underlay single carrier system is investigated. A secondary users' network consists of a control unit (CU) and a group of secondary user remote radio heads (S-RRHs). To effectively access the radio spectrum licensed to the primary users, a distributed cyclic delay diversity (dCDD) scheme is employed between the CU and S-RRHs as the transmit diversity scheme. Multiple primary user transmitters (PTXs) are assumed to be located isotropically within the secondary users' network, so that a mixture of line-of-sight (LoS) and non-line-of-sight (nLoS) paths from the PTXs to the secondary user receiver is considered. In addition, a mixture of LoS and nLoS paths is considered in the secondary users' network. For a new transmit diversity scheme and channel model, the performance of the secondary users' network achieved by the dCDD in the presence of isotropically distributed multiple PTXs is investigated. The dCDD enables the CU to use multiple S-RRHs at the same time, so that determining the effects of a different number of S-RRHs in the presence of a new channel model is an open research issue. To this end, a new closed-form expression for the outage probability is derived, and then its accuracy is verified by link-level simulations.