Joint Distributed Beamforming and Power Allocation in Underlay Cognitive Two-Way Relay Links Using Second-Order Channel Statistics

Abstract

Cognitive underlay amplify-and-forward (AF) two-way relay links require signal-to-interference-and-noise-ratio (SINR) balancing and maximizing strategies. And both secondary-to-primary and primary-to-secondary interference must be taken into consideration. To achieve these goals, we develop several joint distributed beamforming and power allocation algorithms. The development is based on the assumption of the availability of channel state information (CSI) of the relay-transceiver channels and the second-order-statistics (SOS) of all channels. For single-relay and multi-relay systems, a closed-form solution and an exhaustive-search optimal algorithm, respectively, are developed. This optimal algorithm, despite its high computational complexity, serves as a useful benchmark. Moreover, two low-complexity suboptimal algorithms are proposed, both of which compute sub-optimal power allocations and beamformers. A 10-dB SINR improvement by the optimal algorithm and similar gains by both proposed suboptimal algorithms are achievable.Index Terms-Amplify-and-forward relaying, cognitive radio, distributed beamforming, power allocation, second-order statistics of channel gains, SINR balancing, two-way relay, underlay.

Distributed Robust Beamforming Based on Low-Rank and Cross-Correlation Techniques: Design and Analysis

“…Prior work on distributed beamforming [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14] includes several approaches to enhancing the reception of signals originating from relays. In [2], relay network problems are described as optimization problems and relevant aspects and implications are provided and discussed, which gives a general overview and methodologies that are commonly considered to analyze relay networks.…”

“…The studies in [8], [9] analyze power control methods based on channel magnitude, whereas the powers of each relay are adaptively adjusted according to the qualities of their associated channels. The study in [10] uses joint distributed beamforming and power allocation in underlay cognitive two-way relay links using secondorder channel statistics for SINR balancing and maximization. However, most of these approaches are derived by assuming that the global CSI is perfectly known.…”

Performance Analysis of Opportunistic Multi-antenna Relay Selection over Nakagami-m Fading Channels Based RAN for 5G

“…Cooperative diversity has attracted a lot attentions in the 5G networks [1] and in dense networks, the application of relay nodes will be more and more widespread. Although Previous study with Opportunistic Relaying (OR) focusing multiple relays has studied in [2], choosing single relay network brings system capacity loss comparing multiple relay network [3]- [4]. [3] analyzes low complexity OR and studied the performance of outage probability based on both Decode-and-Forward (DF) mode and Amplify-and-Forward (AF) mode under an total power constraint.…”

Efficient spectrum sensing and power allocation for cognitive two‐way relay network

“…The other research interest includes optimal power allocation of secondary users and/or relay selection [11][12][13]. Cao and Tellambura [14] considered the problem of joint power allocation and relay beamforming in a cognitive TWRN.…”