Fundamental capacity for peak interference power constrained cognitive radio relay networks

A Cognitive radio communication link is possible to be interrupted easily when its physical channel suffers severe fading. Relay technology is an effective way to mitigate the fading effect of wireless channels in a network. Based on the highest achievable rate of the relay channels, this paper considers a cognitive radio relay network where the secondary transmitter communicates with the receiver through the best relay node under the peak power constraint of a primary receiver. Intuitively, the secondary transmission can benefit from an intermediate relay node chosen from N possible nodes. To quantify this benefit, outage probability of cognitive radio relay networks is derived and also the closed-form expressions for outage capacity and ergodic capacity of cognitive radio relay networks are obtained in Rayleigh fading channels. Numerical simulation results are provided to show that the outage capacity and ergodic capacity benefit tremendously by properly increasing the number of relaying nodes.

浙江ATM安装先进防盗系统

日前，中国浙江萧山的一家银行在自动取款机上安装了一个防盗系统，这个系统通过三种办法来防盗。首先是语音提示，如果取款人身后还站着一个人，那么柜员机两侧的警示灯就闪了起来，提醒后边的人请站在一米线之外。