Cache-Aided Multiuser Cognitive Relay Networks With Outdated Channel State Information

• Published in: IEEE access 2018-01, Vol.6, p.21879-21887
• Main Authors: Lai, Xiazhi, Xia, Junjuan, Tang, Maobin, Zhang, Haochuan, Zhao, Junhui
• Format: Article
• Language: English
• Subjects: Asymptotic properties; Cache; Channel state information; Cognitive radio; decode-and-forward relay; Diversity reception; Multiaccess communication; multiuser cognitive relay networks; Networks; outdated channel state information; Relay networks; Relay networks (telecommunications); Relaying; Telecommmunication network reliability
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2018.2829026

In this paper, we study the impact of cache on the multiuser cognitive relay networks with outdated channel state information (CSI), where the transmission from the multiple secondary sources to the secondary destination is assisted by one decode-and-forward relay. Two user selection criteria in choosing the best secondary source are used to maximize the channel gain of the direct link or the transmit power at the selected secondary source, respectively. For the considered networks with or without cache, we derive the analytical and asymptotic expressions of the outage probability under the two user selection criteria, respectively. From the asymptotic outage probabilities, we conclude that the system with cache outperforms that without cache, due to the reason that the cache-aided system enhances the system performance by reducing half of the transmission time and eradicating the outage event from the first hop of relaying link. Moreover, we see that the multiuser diversity gains are severely degraded by the outdated CSI. Numerical results are demonstrated to verify the proposed analysis and demonstrate the impact of cache and outdated CSI on the system transmission performance.