Filter-and-forward relaying in cognitive networks with blind channel estimation

• Published in: IET communications Vol. 10; no. 18; pp. 2678 - 2686
• Main Authors: Mohammadkhani, Saeideh, Karagiannidis, George K
• Format: Journal Article
• Language: English
• Published: The Institution of Engineering and Technology 15.12.2016
• Subjects: array signal processing; blind channel estimation; Blinds; channel estimation; channel frequency selectivity mitigation; channel gain; Channels; cognitive radio; cooperative beamforming design; cooperative communication; fading channels; filtering theory; filter‐and‐forward relaying; frequency selective fading channels; interference power; Links; Networks; Noise; primary link; primary transmitter‐relay; radio receivers; radio transmitters; radiofrequency filters; radiofrequency interference; received signal‐to‐interference‐plus‐noise ratio; Receivers; Relay; relay networks (telecommunication); relay nodes; relay‐primary receiver; secondary link; SINR minimisation; total transmit power minimisation; Uncertainty; underlay cognitive relay network; interference power; SINR minimisation; primary link; relay-primary receiver; total transmit power minimisation; channel gain; radiofrequency interference; cognitive radio; fading channels; relay nodes; relay networks (telecommunication); array signal processing; primary transmitter-relay; blind channel estimation; channel frequency selectivity mitigation; filtering theory; filter-and-forward relaying; secondary link; radio receivers; received signal-to-interference-plus-noise ratio; cooperative communication; channel estimation; radiofrequency filters; radio transmitters; cooperative beamforming design; underlay cognitive relay network; frequency selective fading channels
• ISSN: 1751-8628; 1751-8636
• DOI: 10.1049/iet-com.2015.0759

The authors study the design of cooperative beamforming for an underlay cognitive relay network over frequency selective fading channels. The network under consideration consists of one primary link, one secondary link and relay nodes that assist the communication. It is assumed imperfect blind channel estimation, i.e. only the second order statistics – with uncertainty – of the channel gain between the primary transmitter-relay and relay-primary receiver, is available. To mitigate the channel's frequency selectivity, each relay is equipped with a finite impulse response filter, which performs filter and forward relaying. The authors consider two different scenarios: in the first, the objective is to minimise the total transmit power of the relays subject to a constraint on the interference induce on the primary receiver. Furthermore, a constraint is also considered on the received signal-to-interference plus noise ratio (SINR) in the secondary receiver. In the second scenario, the objective is to maximise SINR in the secondary receiver, subject to constraints on the sum power of the relays and also on the noise and interference power in the primary receiver. Simulation results show how total power of relay varies with the uncertainty in the blind channel estimation in the first scenario. In addition, the achievable SINR deteriorates in the second scenario when the uncertainty increases.