A reference signal based GLRT for simultaneous sensing and reception in cognitive LTE-A systems

We explore the application of cognitive radio (CR) principles to 3GPP LTE-A. In such a system, a cognitive radio (CR), synchronized to the macro base station (BS), exploits the spectral holes in the orthogonal frequency division multiple access (OFDMA) time-frequency grid. Spectrum sharing between different network operators and device-to-device (D2D) communications in LTE-A are presented as potential applications. Sensing is expected to play a prominent role in such systems. We focus on simultaneous sensing and reception (SSR) that can avoid the overhead in sensing before transmission (SBT) protocols. Firstly, for a flat fading channel, we develop generalized likelihood ratio tests (GLRTs) based on the demodulation reference signals (DMRSs) of transmission mode 9 in LTE-A that do not require the knowledge of signal powers, channel statistics and noise parameters. Secondly, using a polynomial fitting, we extend the algorithm to frequency-selective fading scenarios. Simulation results are presented to compare the different algorithms which indicate that good performance can be achieved for SSR with full knowledge of the DMRSs.