Distributed Beamforming in Two-Way Relay Networks With Interference and Imperfect CSI

Abstract

This paper studies the problem of optimal beamforming and power allocation for an amplify-and-forward (AF)based two-way relaying network in the presence of interference and channel state information (CSI) uncertainty. In particular, we obtain the beamforming vector as well as the users' transmit powers under two assumptions on the availability of the CSI of the interfering links, namely norm-bounded uncertainty model and the second-order statistics scenario. To do so, we develop two design approaches. The first approach is based on the total transmit power minimization technique. We start with the norm-bounded uncertainty model and derive the optimal solution to the corresponding problem. To reduce the computational complexity, we also develop a low-complexity algorithm which offers performance that is very close to the optimal one. In the second approach, we apply a signal-to-interference-plusnoise ratio (SINR) balancing technique. We propose another low-complexity algorithm based on the SINR balancing criteria. Next, we consider the scenario where the second-order statistics of the CSIs are available. Again we start with the total power minimization method and derive both optimal and sub-optimal algorithms. Finally, we apply the SINR balancing technique to this scenario and develop another low-complexity algorithm which is suitable for practice. respectively. He has worked closely and served several research appointments with the related departments in

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

“…The works in [15], [16] consider the channel errors as Gaussian random vectors with known statistical distributions between the source to the relay nodes and the relay nodes to the destination, whereas [17] models the channel errors on their covariance matrices as a type of matrix perturbation. The work in [17], [19], [20] presents a robust design, which ensures that the SNR constraint is satisfied in the presence of imperfect CSI by adopting a worst-case design and formulates the problem as a convex optimization problem that can be solved efficiently. Similar approaches that use the worst-case method can be found in conventional beamforming as in [21], [22].…”

“…To this point, all the K channel components off k (i) can be obtained so that we haveF k (i) = [f 1 (i),f 2 (i), · · · ,f K (i)]. In the next step, we will use the estimated mismatched channel components to provide estimates for the matrix quantitieŝ R k (i) (k = 1, · · · , K),Q(i) andD(i) in (20) as follows: 6 To proceed further, we defineÛ(i) =Q(i) + K k=2R k (i) so that (20) can be written as…”

“…This subsection presents an analysis of the computational complexity of LRCC-RDB and comparisons with existing robust approaches such as the most common worst-case approaches, which are typically solved using an interior point method (e.g. [17], [19], [20], [74]) and the probabilistic based stochastic approach introduced in [16], all of which are shown in Table II. It should be noted that we compare the computational complexities of the approaches regardless of their system design objectives, which could target the minimization of the total relay transmit power with a QoS (output SNR or SINR) constraint (e.g.…”

Decoupled beamforming techniques for distributed MIMO two-way multi-relay networks with imperfect CSI

“…By taking account into the channel uncertainties, the imperfect CSI scenario has been studied in [20][21][22][23][24][25]. In [20], joint relay and jammer selection and power control for physical layer security issues in two-way relay networks are studied to maximize the secrecy capacity of the network.…”

“…A low complexity processing matrices are presented for a multi-pair two-way massive MIMO AF full-duplex relay system [22]. Specifically, in [23], the problem of optimal beamforming and power allocation for an AF-based TWRN is studied in the presence of interference and CSI uncertainty, where two different approaches, namely the total power minimization method and the signal-to-interference-plusnoise-ratio (SINR) balancing technique, are proposed. Particularly, the robust two-way relay precoder design for a cognitive radio network is investigated in [24], where two different types of CSI errors with corresponding robust designs are proposed.…”