Design of Hybrid Precoder for mm-Wave MIMO system based on Generalized Triangular Decomposition Method

Hybrid precoding techniques are lately involved a lot of interest for millimeter-wave (mmWave) massive MIMO systems is due to the cost and power consumption advantages they provide. However, existing hybrid precoding based on the singular value decomposition (SVD) necessitates a difficult bit allocation to fit the varying signal-to-noise ratios (SNRs) of altered sub-channels.  In this paper, we propose a generalized triangular decomposition (GTD)-based hybrid precoding to avoid the complicated bit allocation The development of analog and digital precoders is the reason for the high level of design complexity in analog precoder architecture, which is based on the OMP algorithm, is very non-convex, and so has a high level of complexity. As a result, we suggest using the GTD method to construct hybrid precoding for mmWave mMIMO systems. Simulated studies as various system configurations are used to examine the proposed design. In addition, the archived findings are compared to a hybrid precoding approach in the classic OMP algorithm. The proposed Matrix Decomposition's simulation results of signal-to-noise ratio vs spectral efficiencie

Sum-Rate Analysis for High Altitude Platform (HAP) Drones with Tethered Balloon Relay

High altitude platform (HAP) drones can provide broadband wireless connectivity to ground users in rural areas by establishing line-of-sight (LoS) links and exploiting effective beamforming techniques. However, at high altitudes, acquiring the channel state information (CSI) for HAPs, which is a key component to perform beamforming, is challenging. In this paper, by exploiting an interference alignment (IA) technique, a novel method for achieving the maximum sum-rate in HAP-based communications without CSI is proposed. In particular, to realize IA, a multiple-antenna tethered balloon is used as a relay between multiple HAP drones and ground stations (GSs). Here, a multiple-input multiple-output X network system is considered. The capacity of the considered M*N X network with a tethered balloon relay is derived in closed-form. Simulation results corroborate the theoretical findings and show that the proposed approach yields the maximum sum-rate in multiple HAPs-GSs communications in absence of CSI. The results also show the existence of an optimal balloon's altitude for which the sum-rate is maximized.Comment: Accepted in IEEE Communications Letter

Analysis of Linear Equalizers for Cooperative Multi-User MIMO Based Reporting System

In this paper, we consider a multi user multiple input multiple output (MU-MIMO) based cooperative reporting system for cognitive radio network. In the reporting network, the secondary users forwards the primary user data to the common fusion center (FC). The FC is equipped with linear equalizers and an energy detector to make the decision about the spectrum. The primary user data is considered to be a digital video broadcasting - terrestrial (DVB-T) signal. The sensing channel and the reporting channel is assumed to be an additive white Gaussian noise and an independent identically distributed Raleigh fading respectively. We analyzed the detection probability of MU-MIMO system with linear equalizers and arrived at closed form expression for average detection probability. Also the system performance is investigated under various MIMO scenarios through Monte Carlo simulations

Analysis of Linear Equalizers for Cooperative Multi-User MIMO Based Reporting System

In this paper, we consider a multi user multiple input multiple output (MU-MIMO) based cooperative reporting system for cognitive radio network. In the reporting network, the secondary users forwards the primary user data to the common fusion center (FC). The FC is equipped with linear equalizers and an energy detector to make the decision about the spectrum. The primary user data is considered to be a digital video broadcasting - terrestrial (DVB-T) signal. The sensing channel and the reporting channel is assumed to be an additive white Gaussian noise and an independent identically distributed Raleigh fading respectively. We analyzed the detection probability of MU-MIMO system with linear equalizers and arrived at closed form expression for average detection probability. Also the system performance is investigated under various MIMO scenarios through Monte Carlo simulations

Optimal overhead selection for interference alignment in time-varying two-user MIMO X channel

Channel state information (CSI) at the transmitter and receiver is an essential requirement for interference alignment (IA) schemes. For moving users the channel coefficients vary with time and, therefore, it is required to update CSI both at the transmitter and receiver at regular intervals. Meanwhile it is important to note that frequent updates of CSI will reduce data rate and delayed updates will cause a large variation in CSI. In this context we explore the error performance of IA in two-user multiple-input multiple-output (MIMO) X channel where the channel suffers continuous time-varying fading. The bit error rate (BER) performance of MIMO two-user X channel is evaluated for different Doppler frequencies. We also propose a method for calculating optimal pilot overhead for time-varying channels by setting an upper bound on BER

Interference alignment for the K-user MIMO X network using time division multiple access

This paper investigates an interference alignment (IA) scheme suitable for a K-user multiple-input multiple-output (MIMO) wireless X network. The K-user MIMO X-network is a communication architecture where each transmitter, equipped with multiple antennas, has independent messages for each of the receivers, also equipped with multiple antennas. Earlier only 2 × N or M × 2 X networks were considered to be achievable. In this paper we remove this restriction by employing time division multiple access scheme. The proposed IA scheme allows each user to achieve a degree of freedom of KA/2K-1 a particular time slot, where A is the number of antennas at each transmitter and receiver. The capacity and bit error-rate (BER) performance of the proposed scheme is compared to that of another scheme recently proposed by Park and Ko. Simulation results are reported to show the BER performance for K-user (for a toy example, K is set equal to 3) and two-user X channel IA in case of transmission over flat-fading Rayleigh channels

Joint Optimization of Precoder and Decoder in Multiuser MIMO Systems

This paper considers the joint optimization of precoder and decoder for both uplink and downlink transmissions in multiuser multiple-input, multiple-output (MU-MIMO) systems. Focusing on the scenario when an improper constellation such as binary phase shift-keying (BPSK) or M-ary amplitude shift-keying (M-ASK) is employed, novel joint linear precoders and decoders are proposed to minimize the total mean squared error (TMSE) of the symbol estimation. The superiority of the proposed transceivers over the previously-proposed designs is thoroughly verified by simulation results

Effect of imperfect CSI on interference alignment in multiple-High Altitude Platforms based communication

Interference Alignment (IA) offers maximum sum-rate in a wireless X channel. Though IA was proposed for maximizing sum-rate, its application for exploiting high data rate in air-to-ground communication has not been explored much. In this paper, the application of IA in a High Altitude Platform (HAP) to Ground Station (GS) communication is considered. Recent studies suggest that IA provides maximum sum-rate for a 2 × 2 transmitter–receiver system. However, independent channels are required to achieve IA conditions. The application of IA is proposed here for a generalized channel in an HAP-to-GS communication link that takes into account angle-of-departure and angle-of-arrival at the transmitter and at the receiver, respectively. We verify the minimum distance criteria in receiving nodes to achieve independent channels. Receivers are placed at optimal distance for best error performance. Furthermore, in view of an actual scenario, we investigate the effect of imperfect CSI, resulting from changes in imperfection in HAP's stabilization, in the performance of our model. The performance, in terms of Bit Error Rate (BER), is presented for IA and non-IA based communication. For this purpose, an analytical expression is developed for the probability of error. A perfect match is shown between the error rate measured with Monte Carlo simulations and the error probability found using the derived analytical expressions

Performance Study of Strongly Coupled Magnetic Resonance

Strongly Coupled Magnetic Resonance (SCMR) uses electromagnetic resonance in order to efficiently transfer power wirelessly over mid-range distances. Since the energy exchange capability of resonant objects higher than non-resonant objects, strongly coupled systems are able to achieve more efficient energy transfer than other wireless power transfer systems. The paper presents detailed experimental and simulated analysis of the performance of the SCMR system. A prototype of the SCMR system was implemented and experiments were conducted to analyze the performance of the system. Finally, the resonant frequency of the system was experimentally verified and the factors influencing the wireless power transfer were also studie