Linear Precoding for Fading Cognitive Multiple-Access Wiretap Channel With Finite-Alphabet Inputs

Abstract

We investigate the fading cognitive multiple access wiretap channel (CMAC-WT), in which two secondary-user transmitters (STs) send secure messages to a secondary-user receiver (SR) in the presence of an eavesdropper (ED) and subject to interference threshold constraints at multiple primaryuser receivers (PRs). We design linear precoders to maximize the average secrecy sum rate for multiple-input multiple-output (MIMO) fading CMAC-WT under finite-alphabet inputs and statistical channel state information (CSI) at STs. For this nondeterministic polynomial time (NP)-hard problem, we utilize an accurate approximation of the average secrecy sum rate to reduce the computational complexity, and then present a two-layer algorithm by embedding the convex-concave procedure into an outer approximation framework. The idea behind this algorithm is to reformulate the approximated average secrecy sum rate as a difference of convex functions, and then generate a sequence of simpler relaxed sets to approach the non-convex feasible set. Subsequently, we maximize the approximated average secrecy sum rate over the sequence of relaxed sets by using the convexconcave procedure. Numerical results indicate that our proposed precoding algorithm is superior to the conventional Gaussian precoding method in the medium and high signal-to-noise ratio (SNR) regimes.Index Terms-Finite-alphabet inputs, linear precoding, MIMO, statistical CSI, physical-layer security, cognitive multiple access wiretap channel.

Transmit Antenna Selection and Beamformer Design for Secure Spatial Modulation With Rough CSI of Eve

“…The noise levels at the desired receiver and at the eavesdropping receiver are assumed to be identical, i.e., σ 2 B = σ 2 E . Additionally, the ergodic SR is averaged over 500 channel realizations according to (10). Fig.…”

“…Since the number of TAs is not a power of two, it is necessary to select an AAG and to design AN for enhancing the security. From the definition of (10), the optimization problem of maximizing the SR (Max-SR) can be cast as…”

“…In what follows, we will present a lower complexity algorithm for optimizing S and Q = E(TT H ), which has the capability to approach the SR performance of Algorithm 1. Once the corresponding optimal solution is obtained, the ergodic SR is evaluated by (10). We circumvent the difficulty by avoiding the calculation of multiple integrals in the SR expression, where the corresponding approximate MI (AMI) is given by…”

“…Due to the broadcast nature of radio propagation, its security problem has to be considered, since various types of wireless access devices may overhear the private messages. Traditionally, the security of a communication system has been ensured through cryptography and authentication in the network layer, which often imposes additional computational complexity for key generation and complex decryption algorithms [10] [11]. However, the key distribution and management is challenging for large-scale wireless networks.…”

Optimal rotation angle for finite constellation over additive white Gaussian noise multiple access wiretap channel

“…For a review of finite alphabet signalling over a wiretap channel, one can refer to [10]. A linear pre‐coding over a fading cognitive multiple access wiretap channel (MAC‐WT) is discussed in [11]. A finite constellation over an amplify and forward relay channel with security constraints is studied in [12].…”