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In this paper, performance of a novel analytic model of direct sequence code division multiple accesses (DS-CDMA) using diversity with maximal ratio combining (MRC) scheme is observed under the influence of multipath Rayleigh fading and multi-access interference (MAI) varying different system parameters and properties of PN sequences. The analysis presents a mathematical expression for bit error rate...
The tremendous capacity gains promised by space division multiple access (SDMA) depend critically on the accuracy of the transmit channel state information. In the broadcast channel, even without any network interference, it is known that such gains collapse due to interstream interference if the feedback is delayed or low rate. In this paper, we investigate SDMA in the presence of interference from...
We show that while the multiplexing effect of the spatial multiplexing MIMO channel has the greatest influence on ergodic capacity at infinite SNR, the contribution of diversity to enhancing ergodic capacity at finite SNR is comparable to or greater than that of multiplexing as the number of antennas increases to a moderate level. For instance, we show that the contribution of diversity to ergodic...
Sparse space codes (SSC) are proposed as a novel transmission scheme for an under-determined MIMO channel. Each SSC codeword is a sparse vector of the size of the number of transmit antennas. The information is imparted through: (i) uncertainty in the positions of non-zero elements, and (ii) uncertainty in the symbol-space of non-zero elements. Basis-pursuit (BPD) and LASSO detectors are used with...
This paper investigates the performance enhancements using radio-frequency (RF) beamforming on closely spaced antennas in multiple-input multiple-output (MIMO) communication system. Of specific interest is the case of a array of extremely closely spaced antennas with complexity constraints, here implemented being restricted to a single RF chain. Our system model is developed in context of closely...
Log-likelihood ratios (LLRs) are efficient metrics used in the decoding of modern channel codes such as low-density parity-check and turbo codes. LLR calculation, however, can be a complex task since LLRs are usually complicated nonlinear functions of the channel output. In multi-input multioutput (MIMO) channels, the complexity of the calculation increases exponentially with the number of antennas...
Multiple Input Multiple Output (MIMO) methods significantly improve the coverage of Power Line Communications (PLC) compared to Single Input Single Output (SISO) systems. This paper describes the implementation and results of the first real-time MIMO PLC feasibility study. Our system setup includes two PCs, each containing two FPGAs. It enables the comparison of SISO versus MIMO PLC transmissions...
Inhome Power Line Communications (PLC) enables new and highly convenient networking functions without any additional wires to mains-powered devices. Multiple Input Multiple Output (MIMO) methods significantly improve the coverage of guaranteed data throughputs in private homes. This paper gives an overview on MIMO PLC. The results from the channel measurements motivate to implement a MIMO PLC feasibility...
This paper presents statistical information about the company's field data. First of all, a monitoring tool is presented which offers the opportunity to collect reports. These reports are periodically sent by each PLC device and collected in a central database. They show the network topology and provide information concerning the channel characteristic such as the signal to noise ratio (SNR), the...
This survey examines the bandwidth efficiency of wireless signals, beginning with a review of the Shannon capacity and of the important differences between signal to noise ratio (snr) and individual bit energy to noise density (IBEND = Eb/N0). Recognizing that communication systems are successful only if they are profitable, value propositions that have been realized along the evolution of adopted...
In this paper, the information extracted from Single-Input Multiple-Output sounding measurements is used to study the effect of several aspects of the receive antenna arrays on system performance. The extracted multipath parameters are used to synthesize the MIMO channel matrices of a hypothesized communication system having a fixed microcellular base-station and a handheld terminal moving throughout...
A MIMO interference network with L users is investigated in this paper. We compare the sum-rate performance of interference management approaches applied to this network. The minimum mean square error (MMSE) algorithm optimizes the beamforming vectors by maximizing the signal-to-interference-plus-noise ratio (SINR). Another approach, minimum leakage interference alignment (ML-IA), minimizes the leakage...
Multiple input multiple output (MIMO) communication architecture has spectral efficiencies far beyond those offered by conventional techniques, and is greatly to increase the channel capacity. In this paper, we investigate the MIMO channel capacity in correlated channels using the uniform angular distribution, numerical simulations are performed with Matlab to verify the proposed formula. We prove...
Being reliable and real-time, are the two most challenging requirements of wireless sensor and actuator networks (WSAN) due to the shared, error-prone and nondeterministic behaviour of wireless communication medium. In this paper, an adaptive data-rate and space-time coding (STC) scheme has been proposed for the IEEE 802.11-based Soft-Real-Time WSAN's utilizing Enhanced Distributed Channel Access...
The problem of blind channel estimation in Multiple-Input-Multiple-Output (MIMO) Orthogonal Frequency-Division Multiplexing (OFDM) systems is investigated in this study, assuming that the transmitted symbols are independent and identically distributed. In particular, by utilizing a generalized linear non-redundant precoder, a simple blind channel estimation technique for MIMO-OFDM systems is developed...
In this paper, we consider user selection algorithms for Multi-user MIMO systems with perfect or partial channel state information at the transmitter (CSIT). A novel user selection algorithm based on chordal distance is proposed. The basic principle is to serve the user subset in which one is approximately orthogonal to the others. Since the chordal distance relies only on the channel direction information,...
The concept of interference alignment has been studied mainly from an information-theoretic and signal processing point of view, focusing on scenarios with a high degree of coordination among nodes often achieved by means of transmission scheduling. However, many real-world networks employ random access policies rather than deterministic scheduling, and it is therefore important to understand how...
In this paper, we consider a slow-fading nt ×nr multiple-input multiple-output (MIMO) channel subjected to block fading. Reliability (in terms of achieved diversity order) and rate (in number of symbols transmitted per channel use) are of interest in such channels. We propose a new precoding scheme which achieves both full diversity (nt ×nrth order diversity) as well as full rate (nt symbols per channel...
In this paper, we propose a codebook construction method for multiple-input multiple-output (MIMO) beamforming systems operating under the per-antenna power constraint (PAPC). Under the PAPC which limits the individual power of each transmit antenna, it is known that only phase steering information is required to form the optimal beamforming vector at the transmitter. For systems with non-reciprocal...
Hierarchical femtocell architectures have become popular recently because of their potential to provide increased coverage and capacity in cellular systems. However, introduction of femtocells might reduce the overlay macrocell system performance due to increased interference caused to macrocel-lular users. With MIMO precoding, the Least Interference (LI) technique can be employed at the femtocellular...
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