Distributed Asynchronous Cyclic Delay Diversity-Based Cooperative Systems with a Passive Eavesdropper

A joint data and jamming transmission scheme based on a new distributed asynchronous cyclic delay diversity (dACDD) scheme is proposed for cooperative communication systems. Without any exact knowledge of channel state information (CSI) at the transmitting side, a joint remote radio head (RRH) selection scheme for the data and jamming signal transmissions is proposed for dACDD to achieve the maximum diversity gain at a legitimate user (LU), while degrading the receive signalto-interference-plus-noise ratio at an eavesdropping user (EU). A single RRH connected with the channel having the greatest channel gain is selected as a data RRH that transmits a desired confidential signal, whereas the remaining RRHs are controlled by the central control unit to transmit an artificial noise sequence (ANS) to the LU and EU. Without assuming exact knowledge of CSI of the whole system, the secrecy outage probability of the distributed communication system is analyzed by deriving a closed-form expression, and through link-level simulations over non-identically distributed frequency selective fading channels over the entire system.