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This paper introduces a simple and practical channel estimator for multipath multi-cell massive MIMO TDD systems with pilot contamination. Least squares (LS) channel estimators present low performance under moderate to strong pilot contamination, while minimum mean square error (MMSE) estimators perform much better than LS estimators in such conditions. However, MMSE estimators present an issue that...
Cooperative relay has been an interesting research area for the past years as it promotes higher data rates and robust to wireless environment. IEEE Work Group initiated the use of relay stations in the IEEE 802.16e standard and it is called IEEE 802.16j. This paper proposed a multi-hop cooperative relay system with space-time codes (STC), with the integration of relay selection. In changing environment,...
In this paper, we analyze the performance of cooperative diversity using adaptive Decode and Forward (DF) relaying over independent non identical flat composite fading channels which include multipath fading and shadowing simultaneously. We have considered the generalized-K model which is very versatile and accurately approximates many of the commonly used channel models as Nakagami-m, log-normal...
Multipath fading is inherent in wireless communication systems. Diversity is the techniques which takes the advantage of multipath and mitigate the effect of fading and increase signal strength. Space Time Block codes (STBC) are used in MIMO systems to improve the performance by maximizing transmit and/or receive diversity. Among different schemes based on STBC, Quasi orthogonal space time block code...
The effects of multipath fading systems have been extensively analysed in telecommunications literature, however, with less attention to polarization mismatch considerations. The purpose of this work is to present a novel way to treat this aspect, resulting in the development of expressions with direct application in the design of the radiobase receiving part of modern mobile radio systems. The technique...
It is a challenging task to handle dense multipath environment in a wireless communication channel. Various techniques were suggested to handle this issue such as power control, antenna, time and frequency diversity etc. However, antenna diversity is considered to be the most practical way to handle multipath fading. In this paper, a deterministic UWB channel model was developed based on ray-tracing...
Based on the factor graph, a joint channel estimation and detection method is proposed for orthogonal frequency division multiplexing (OFDM) systems employing multiple transmit and receive antennas (MIMO). Using belief propagation, statistics of the fast varying MIMO multipath channel are utilized in estimating channel coefficients. By proper message scheduling and passing, the proposed receiver is...
Relay networks achieve high performance by utilizing cooperation between nodes which can classified as multi-hop networks and cooperative MIMO relaying networks. Cooperative diversity is a transmission technique to overcome fading, multipath and inter-channel interference. As an important part of "spatial diversity" systems, cooperative diversity involving multi hop data relays is a solution...
It is well known that the realization of enormous capacity of multiple-input multiple-output (MIMO) channels depends greatly on the accuracy of channel estimation at the receiver. And the problem of designing optimal pilot or training sequences is crucial to channel estimation. In this paper, the optimal pilot sequences are designed by maximizing the mutual information (carried by pilot tones) between...
In cellular mobile communications, multipath fading, shadowing, near-far problem and the Doppler effect have led to a complex radio wave propagation environment. Furthermore, with the continuously increasing of users and operations, not only new bandwidth is required, new technologies and measures are also expected to improve the system capacity and channel capacity. This paper introduces the general...
An experimental investigation of handset MIMO antennas with dual-band operation was performed using the data from a radio propagation test in an urban area of Aalborg city in Denmark and an over-the-air test using a spatial fading emulator. It is concluded from the agreement between MIMO characteristics of the both measurements that the emulator is effective in evaluating handset MIMO arrays in the...
MIMO-OFDM is the promising technique in the future of wireless communications as it combines the properties of Multiple Input Multiple Output (MIMO) systems with those of Orthogonal Frequency Division Multiplexing (OFDM). However, it is very sensitive to frequency offsets which result in inter-carrier interference (ICI). Therefore, to precisely recover the transmitted data, frequency offset compensation...
Transmission environment of mine laneway is non-free, wireless communication reliability is reduced by multi-path fading. MIMO can efficiently overcome multi-path fading, but MIMO channels in mine laneways have strong correlation. In this paper, the performances of space-time code in mine laneway are investigated, and the pair wise error probability (PEP) about mine laneway is analyzed. Following...
In this paper, a rake diversity combining scheme for detection of a single data stream in ultra-wideband (UWB) multiple input multiple output (MIMO) systems is considered as an extension of single input multiple output (SIMO) systems. The BER performance of a linear receive rake diversity scheme is presented in a log-normal multipath fading channel. It is shown that the increase of an antenna dimension...
In this paper, we consider a MIMO multiuser system in a multipath fading channel. We design a blind receiver for a differential space-time coded modulation. A linear estimator projects the received signal onto the same subspace of the MMSE filter. The system works because of the differential encoding of the information matrices. Numerical results show that the blind receiver has the same performance...
This paper proposes a three-dimensional (3-D) model for wideband multiple-input multiple-output (MIMO) vehicle-to-vehicle (V-to-V) multipath fading channels that accounts for mutual coupling among both, transmit and receive antenna elements. From the 3-D model, the spatial correlation is derived for a 3-D non-isotropic scattering environment. Finally, this model is used to evaluate the effect of mutual...
The MIMO (Multiple Input Multiple Output) systems can efficiently mitigate the severe multipath fading effects in underground tunnels. Due to the unique tunnel channel characteristics, there exist optimal antenna geometries that can maximize the MIMO channel capacity. In this paper, an optimal MIMO antenna geometry design scheme is developed based on the analysis of the channel capacity in underground...
This paper proposes a three-dimensional (3-D) model for narrowband multiple-input multiple-output (MIMO) vehicle-to-vehicle (V-to-V) multipath fading channels that accounts for mutual coupling among both, transmit and receive antenna elements. This model is used to evaluate the effect of mutual coupling on the antenna element patterns and capacity of MIMO V-to-V systems in a variety of urban environments.
MIMO-OFDM system is the main technology to the future wireless system. In this paper, to model multipath propagation and spatial-temporal fading correlation in frequency-selective channel, we propose a fading-correlated MIMO channel model. The channel is abstracted as a cluster-based double bounce model with multiple taps. Both transmitter and receiver are considered. The expressions of correlation...
In this paper, we consider a multiuser distributed MIMO system, under multipath fading channels, with orthogonal frequency division multiplexing (OFDM) technology. The aim is to extend and evaluate, co-located precoding schemes that have been recently proposed, in a distributed scenario. Assuming knowledge of CSI prior to transmission, we can remove the interference among users by employing precoding...
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