Overlay Cognitive Radio Based on OFDM with Channel Estimation Issues

Date
2019-05-09
Authors
Abdou, Ahmed
Abdo, Ali
Jamoos, Ali
Journal Title
Journal ISSN
Volume Title
Publisher
Springer Science+Business Media
Abstract
Cognitive radio (CR) has been proposed as a technology to improve the spectrum efficiency by giving an opportunistic access of the licensed-user spectra to unlicensed users. We consider an overlay CR consisting of a primary macro-cell and cognitive small cells of cooperative secondary base stations (SBS). We suggest studying a CR where an orthogonal frequency division multiplexing is used for both the primary users (PU) and the secondary users (SU). In order to cancel the interferences, a precoding is required at the SBS. Therefore, we first derive the interferences expression due to SU at the PU receiver. Then, zero forcing beamforming (ZFBF) is considered to cancel the interferences. However, applying ZFBF depends on the channels between the SBS and the PU. A channel estimation is hence necessary. For this purpose, we propose to approximate the channel by an autoregressive process (AR) and to consider the channel estimation issue by using a training sequence. The received signals, also called the observations, are considered to be disturbed by an additive white measurement noise. In that case, the AR parameters and the channel can be jointly estimated from the received noisy signal by using a recursive approach. Nevertheless, the corresponding state space representation of the system is non-linear. Then, we propose to carry out a complementary study by compare non-linear Kalman filter based approaches.
Description
Keywords
Overlay cognitive radio, OFDM, Channel estimation, Nonlinear Kalman filters
Citation
TY - JOUR AU - Abdou, Ahmed AU - Abdo, Ali AU - Jamoos, Ali PY - 2019/05/09 SP - T1 - Overlay Cognitive Radio Based on OFDM with Channel Estimation Issues DO - 10.1007/s11277-019-06455-2 JO - Wireless Personal Communications ER -