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Massive MIMO is a promising technology for 5G. While its advantages of increasing capacity and reducing output power are clear, understanding its SNR requirements in practical cases lacks sufficient theoretical support. This paper computes the relative power levels of the different signal, interference and noise terms in a Massive MIMO system using Maximum-Ratio Transmission (MRT). This brings light...
In this paper, the impact of in-band full-duplex (IBFD) wireless communications on secret key generation via physical layer channel state information is investigated. A key generation strategy for IBFD wireless devices to increase the rate of generated secret keys over multipath fading channels is proposed. Conventionally, due to the half-duplex (HD) constraint on wireless transmissions, sensing simultaneous...
This paper addresses the problem of pilot contamination in multi-cell multiuser Large-Scale Multiple-Input Multiple-Output (LS-MIMO) aided orthogonal frequency division multiplexing (OFDM) systems, and the exact closed-form expression for the mean square error (MSE) of the classical least square (LS) channel estimation algorithm is derived. Then, a pilot design criterion is proposed to design the...
In this paper, we investigate the physical layer discriminatory channel estimation (DCE) in multiple-input multiple-output (MIMO) decode-and-forward (DF) relay systems which comprise a source, a relay, a destination, and an eavesdropper node. In the first channel estimation phase (phase 1), the relay transmits a training signal while the source transmits a cooperative jamming signal omnidirectionally,...
Multiple-input multiple-output (MIMO) systems constitute an important part of todays wireless communication standards and these systems are expected to take a fundamental role in both the access and backhaul sides of the emerging wireless cellular networks. Recently, reported measurement campaigns have established that various outdoor radio propagation environments exhibit sparsely structured channel...
The massive multiple-input multiple-output (MIMO) has been proposed as one of the key technologies for the next generation wireless communication systems. Uniform planar array (UPA) antenna structures have been considered in many researches because it is able to deploy a large number of antennas in a relatively small area. There are lots of performance superiorities in massive MIMO systems. However,...
In molecular communication (MC) systems, the expected number of molecules observed at the receiver over time after the instantaneous release of molecules by the transmitter is referred to as the channel impulse response (CIR). Knowledge of the CIR is needed for the design of detection and equalization schemes. In this paper, we present a training-based CIR estimation framework for MC systems which...
Acquisition of accurate channel state information (CSI) at the base station (CSIT) is a major challenge of deploying frequency-division duplexing (FDD) massive MIMO systems. Although compressive sensing (CS) based CSIT estimation approaches have been proposed to reduce the pilot training overhead for massive MIMO systems, the existing schemes cannot properly dimension the minimum required pilot symbols...
This paper proposes a novel channel estimation scheme for the multiuser massive multiple-input multiple-output (MIMO) systems. A discrete Fourier transform (DFT) aided spatial basis expansion model (SBEM) is first introduced to represent the uplink (UL)/downlink (DL) channels with much few parameter dimensions by exploiting the physical characteristics of the uniform linear array (ULA). With SBEM,...
The paper presents a new channel estimation scheme for downlink 60GHz indoor environment with Massive Multiple Input Multiple Output (Massive MIMO) systems by exploiting the physical characteristics of the uniform planar array (UPA) and 2-dimensional discrete Fourier Transform (2D-DFT) operation. The proposed channel estimation algorithm can be carried out with very small number of training resources,...
In millimeter-wave (mmWave) MIMO systems, while a hybrid digital/analog precoding structure offers the potential to increase the achievable rate, it also faces the challenge to lower channel estimation time due to a large number of antennas at both Tx/Rx sides. In this paper, the channel estimation is realized via multi-beam search, and a new hierarchical multi-beam search scheme, which uses a pre-...
Accurate channel state information at the transmitter (CSIT) is essential to achieve multiplexing gains in multi-user (MU) MIMO systems through precoding at the base station (BS). In conventional frequency division duplexing (FDD) systems, CSIT is obtained through downlink pilot-aided channel estimation and limited uplink feedback. However, the resources consumed by training and feedback become unacceptable...
Technologies for millimeter wave (mmWave) communication are at the forefront of investigations in both industry and academia, as the mmWave band offers the promise of orders of magnitude additional available bandwidths to what has already been allocated to cellular networks. The much larger number of antennas that can be supported in a small footprint at mmWave bands can be leveraged to harvest massive-MIMO...
The second generation (2G) cellular networks are the current workhorse for machine-to-machine (M2M) communications. Diversity in 2G devices can be present both in form of multiple receive branches and blind repetitions. In presence of diversity, intersymbol interference (ISI) equalization and co-channel interference (CCI) suppression are usually very complex. In this paper, we consider the improvements...
We consider a time-division duplexing multi-user massive multiple-input multiple-output system, where a so-called beamforming training (BFT) occurs prior to the downlink (DL) data transmission. The BFT process helps the users to obtain the estimates of effective channels, and thus facilitates a more reliable DL data detection compared to the conventional case, where the users have only the statistic...
In the process of wireless communication, channel effects are always a factor of degradation in offered quality. Major channel effects such as noise effects, fading, multipathing, Doppler shift etc., results in degradation in the observed quality of service for the communication system. Various approaches are developed towards the appropriate estimation of these channel effects at the receiver side...
Based on Gibbs sampling technology, this paper puts forward a new semi-blind joint channel estimation and equalization algorithm that used in signal carrier coherent underwater acoustic communication system. First of all, we estimate the channel by using the train sequence with a loop structure before the data, and according to the sparse characteristics of underwater acoustic channel, this paper...
A direct-adaption based bidirectional turbo equalizer (DA-BTEQ) is proposed for multiple-input multiple output (MIMO) underwater acoustic (UWA) communications. Abandoning the traditional channel estimation process, the proposed DA-BTEQ works in a direct-adaption mode and is implemented with bidirectional soft-decision feedback equalizer (SDFE) to suppress error propagation. The diversity gain is exploited...
In this paper, the methods for estimating and tracking sparse doubly spread channels in single-carrier coherent communications are investigated. The sparse doubly spread channel is parameterized by a few paths with different delays, Doppler scales, and gains. Based on the model, a low-complexity channel estimation algorithm is proposed. The channel estimation is divided into two stages, the first...
In this paper, a timing synchronization technique for orthogonal frequency division multiplexing (OFDM) systems in visible light communications (VLC) environments is presented. The proposed synchronization scheme is based on the timing estimation method by Park et al. [1], but considering a new preamble weighted by Shapiro-Rudin sequences [2]. The performance of the new designed method is evaluated...
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