Sub-channels selection schemes with interference management for underlay cognitive networks

Abstract

Cognitive Radio is a promising concept that offers solution to spectral crowding problem by introducing opportunistic usage of the unoccupied licensed frequency bands. Improving the network capacity and reliability of the communication has been recently studied and this through the introduction of cooperative technology in the CR networks. Furthermore, OFDM system is considered to be a good candidate to enhance the flexibility of the CR network, where individual carriers can be switched off for occupied frequencies by the primary user (PU) or for interfering Sub-channels. In this paper, an underlay cognitive network based on OFDM technique is proposed where secondary users (SUs) coexisting with a PU are adhering to stringent interference threshold constraint. Cooperative technology will help improving the CR network performances under PU limitation. This paper proposes new Sub-channel selection schemes which adapt either the transmission power or the sequential order of selection to enhance the system performances. We first provide the exact probability density function (PDF) of the received SNR at the secondary destination. Then, the PDFs are used to derive closed form expressions of the outage probability, the average BER and the ergodic capacity. Analytic results are validated by simulation for the proposed Sub-channels selection schemes.

Effective area spectral efficiency for wireless communication networks with interference management

“…In wireless communication systems, the most conventional performance metrics focus on the quantification of either link reliability or spectral efficiency [5][6][7][8]. The link reliability is usually quantified in terms of outage *Correspondence: omriaymen@qu.edu.qa 1 Electrical Engineering Department, Qatar University, Doha, Qatar Full list of author information is available at the end of the article probability or average error rate [5,6], while the ergodic capacity addresses the spectral efficiency of wireless links, defined as the maximum achievable average spectrum efficiency [7,8].…”

“…The link reliability is usually quantified in terms of outage *Correspondence: omriaymen@qu.edu.qa 1 Electrical Engineering Department, Qatar University, Doha, Qatar Full list of author information is available at the end of the article probability or average error rate [5,6], while the ergodic capacity addresses the spectral efficiency of wireless links, defined as the maximum achievable average spectrum efficiency [7,8]. In the system/network level, european telecommunications standards institute (ETSI) defines the energy efficiency metric as the ratio of coverage area over power consumption at the base station [9].…”

Inter-relay interference cancellation for wireless multi-user multi-decode-and-forward relay networks

“…The disadvantage of this method is the use of extra antenna at the different nodes. In [7], a power adaptation scheme was used to manage the IRI by adjusting the transmission power at each relay to satisfy the interference constraint at the next used relay, i.e., the maximum received interference at each relay should be less than a predefined interference threshold (I th ). Another technique is introduced in [8], and consists of using a relay selection criterion (max min) considering the signal to interference-plus-noise ratio (SINR) of the first hop, and the SNR of the second hop in order to select for each user the relay that have the maximum of the minimum between the SINR and the SNR.…”

“…Other major contribution in our paper includes the derivation of the exact closed-form expressions of the average outage probability and BER for general M-ary pulse amplitude modulation (M-PAM) to validate the advantage of the proposed scheme in enhancing interference management for wireless cooperative networks with realistic scenario, where the average SNRs of the second hop are different. The proposed scheme is compared with the techniques presented in [7], and [8] to validate the performance enhancements. We have simulated the techniques presented in [7], and [8] within our numerical results as well as the full interference cancellation (FIC) case as simulation performance benchmark for the proposed scheme.…”

“…The proposed scheme is compared with the techniques presented in [7], and [8] to validate the performance enhancements. We have simulated the techniques presented in [7], and [8] within our numerical results as well as the full interference cancellation (FIC) case as simulation performance benchmark for the proposed scheme. The FIC scheme is based on the ideal case, where we assume that the IRI is fully canceled, i.e., the simulation results for the FIC scheme was conducted based on the desired signal only and without adding the IRI signal.…”