tailieunhanh - Báo cáo toán học: " Optimized spectrum sensing algorithms for cognitive LTE femtocells"

Tuyển tập các báo cáo nghiên cứu khoa học ngành toán học được đăng trên tạp chí toán học quốc tế đề tài: Optimized spectrum sensing algorithms for cognitive LTE femtocells | Abdelmonem et al. EURASIP Journal on Wireless Communications and Networking 2012 2012 6 EURASIP Journal on . http content 2012 1 6 Wireless Communications and Networking a SpringerOpen Journal RESEARCH Open Access Optimized spectrum sensing algorithms for cognitive LTE femtocells Mahmoud A Abdelmonem Mohammed Nafie Mahmoud H Ismail and Magdy S El-Soudani Abstract In this article we investigate to perform spectrum sensing in two stages for a target long-term evolution LTE signal where the main objective is enabling co-existence of LTE femtocells with other LTE femto and macrocells. In the first stage it is required to perform the sensing as fast as possible and with an acceptable performance under different channel conditions. Toward that end we first propose sensing the whole LTE signal bandwidth using the fast wavelet transform FWT algorithm and compare it to the fast Fourier transform-based algorithm in terms of complexity and performance. Then we use FWT to go even deeper in the LTE signal band to sense at multiples of a resource block resolution. A new algorithm is proposed that provides an intelligent stopping criterion for the FWT sensing to further reduce its complexity. In the second stage it is required to perform a finer sensing on the vacant channels to reduce the probability of collision with the primary user. Two algorithms have been proposed for this task one of them uses the OFDM cyclic prefix for LTE signal detection while the other one uses the primary synchronization signal. The two algorithms were compared in terms of both performance and complexity. 1. Introduction Spectrum scarcity has become one of the serious problems facing the wireless communications regulatory bodies especially when the wireless applications and standards are increasing significantly. At the same time a recent study by the United States Federal Communications Commission FCC shows that most of the allocated spectrum in the US is under-utilized 1 . .