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Large-scale multi-cell multiuser multiple-input multiple-output (LS-MIMO) systems can greatly increase the spectral efficiency. But the performance of these systems is deteriorated by pilot contamination. In this paper, first, a pilot design criterion is proposed by exploiting the orthogonality of channel vectors of LS-MIMO systems. Second, following this(More)
In this paper, an approach of estimating signal parameters via rotational invariance technique (ESPRIT) is proposed for two-dimensional (2-D) localization of incoherently distributed (ID) sources in large-scale/massive multiple-input multiple-output (MIMO) systems. The traditional ESPRIT-based methods are valid only for one-dimensional (1-D) localization of(More)
In this paper, we pioneer the study of physical-layer security in heterogeneous networks (HetNets). We investigate secure communications in a two-tier downlink HetNet, which comprises one macrocell and several femtocells. Each cell has multiple users and an eavesdropper attempts to wiretap the intended macrocell user. First, we consider an orthogonal(More)
As an extension of wireless sensor network in underwater environment, underwater acoustic sensor networks (UASNs) have caused widespread concern of academia. In UASNs, the efficiency and reliability of data transmission are very challenging due to the complex underwater environment in variety of ocean applications, such as monitoring abnormal submarine oil(More)
In this paper, we propose a pair of low-complexity user selection schemes with zero-forcing precoding for multiuser massive multiple-input–multiple-output downlink systems, in which the base station is equipped with a large-scale antenna array. First, we derive approximations of the ergodic sum rates of the systems invoking the conventional random(More)
We investigate the outage probability of a variablegain amplify-and-forward (AF) relay network. A multi-source multi-relay network is considered with one destination and twoway traffic, where each node is equipped with two antennas and works on a full-duplex (FD) transmission mode. Meanwhile, the number of sources and relays is M and N, respectively. The(More)
In this letter, a sphere decoding (SD) based noncoherent multiple symbol detection (MSD) scheme is proposed for differential space-time block coded (DSTBC) ultra-wideband (UWB) impulse radio systems. Exhaustive search based maximum likelihood (ML) MSD is impractical in DSTBC-UWB systems since its complexity exponentially increases with observation window(More)
Synchronization is a crucial task and big challenge for ultra-wideband (UWB) systems, especially in the presence of inter-symbol interference(ISI) and inter-frame interference (IFI). This paper proposes a blind synchronization and demodulation algorithm that is capable of mitigating ISI and IFI for noncoherent UWB system. Employing a series of codeword(More)
In this paper, we propose a new interference alignment scheme with limited feedback for the two-cell interfering multi-user multiple-input multiple-output multiple access channel (MIMO-MAC), which provides better performance compared with other schemes when the number of feedback bits is same. Then, we analyse the rate loss for the quantization error, and(More)