%0 Journal Article %T Closed-Form Expressions for Relay Selection with Secrecy Constraints %A Xiaojun Sun %A Chunming Zhao %A Ming Jiang %J Mathematics %D 2010 %I arXiv %X An opportunistic relay selection based on instantaneous knowledge of channels is considered to increase security against eavesdroppers. The closed-form expressions are derived for the average secrecy rates and the outage probability when the cooperative networks use Decode-and-Forward (DF) or Amplify-and-Forward (AF) strategy. These techniques are demonstrated analytically and with simulation results. %U http://arxiv.org/abs/1004.1277v1