Abstract
Despite many attractive features of an orthogonal frequency-division multiplexing (OFDM) system, the signal detection in an OFDM system over multipath fading channels remains a challenging issue, particularly in a relatively low signal-to-noise ratio (SNR) scenario. This paper presents an iterative synchronization-assisted OFDM signal detection scheme for cognitive radio (CR) applications over multipath channels in low-SNR regions. To detect an OFDM signal, a log-likelihood ratio (LLR) test is employed without additional pilot symbols using a cyclic prefix (CP). Analytical results indicate that the LLR of received samples at a low SNR can be approximated by their log-likelihood (LL) functions, thus allowing us to estimate synchronization parameters for signal detection. The LL function is complex and depends on various parameters, including correlation coefficient, carrier frequency offset (CFO), symbol timing offset, and channel length. Decomposing a synchronization problem into several relatively simple parameter estimation subproblems eliminates a multidimensional grid search. An iterative scheme is also devised to implement a synchronization process. Simulation results confirm the effectiveness of the proposed detector.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
