Spatial Multiplexing Research Papers - Academia.edu (original) (raw)

Multiple Input Multiple Output (MIMO) technology refers to wireless communication systems employing multiple antennas at either the transmitter end or the receiver end or both. In recent times, use of multiple transmit and receive antenna... more

Multiple Input Multiple Output (MIMO) technology refers to wireless communication systems employing multiple antennas at either the transmitter end or the receiver end or both. In recent times, use of multiple transmit and receive antenna for enhancing spectral efficiency in a wireless system has established much interest in research field. The solution to obtain superior data rates and better range performance at the same time is OFDM integrated with MIMO technique which is based on IEEE 802.11n standard. The main trouble in front of the wireless multipath propagation is the interference between information symbols transmitted through neighboring channels also called as Inter Symbol Interference (ISI). This could be avoided if we use OFDM technology. Thus MIMO combined with OFDM has got significant importance in future wireless communication system. The major properties of MIMO system involve Spatial Diversity and Spatial Multiplexing which are the main factors to discuss and matter of concern to achieve reliability and high speed data rate. In this paper, we study the performance gain of MIMO-OFDM systems. The main investigation carried out in the following paper is to deal with various Wireless channel models in Spatial Multiplexing (SM) mode. The paper deals with MIMO-OFDM system analysis in various Wireless channel models (Rayleigh, Rician, Nakagami and 3GPP channel Environment) focusing on error rate performance, throughput and Spectral gain in 4x4 MIMO scheme under OFDM system. Evaluation of Bit Error Rate and throughput with respect to varying Eb/No for 4x4 MIMO-OFDM in Spatial Multiplexing mode, employing 16 QAM modulation with N=128 OFDM subcarriers employing MMSE detection, is the baseline of this paper.

We address the problem of transmit beamforming under channel uncertainties for a multiuser MIMO system, where both the transmitter and the receiver are equipped with multiple antennas. In transmit beamforming multi-user multiplexing is... more

We address the problem of transmit beamforming under channel uncertainties for a multiuser MIMO system, where both the transmitter and the receiver are equipped with multiple antennas. In transmit beamforming multi-user multiplexing is performed using spatial diversity techniques so that a base station could serve multiple users in the same frequency band enabling a substantial saving in bandwidth utilization. However, such techniques require nearly perfect knowledge of the channel state information at the transmitter, which is generally not available in practise. In this paper, we propose robust spatial multiplexing schemes based on a worst case performance optimization by incorporating imperfect channel state information. In the simulation, we have examined two scenarios. In the first the channel state information is assumed to have Gaussian distribution errors. In the second scenario, we analyze the performance for errors introduced due to a partial channel state information feedback scheme. In both scenarios, the proposed robust scheme outperforms the conventional scheme.

Equalization in the time domain is a well-known technique for combating intersymbol interference (ISI) in frequency selective channels. We derive the general structure of the linear zero forcing (ZF) equalizing filters for multiple input... more

Equalization in the time domain is a well-known technique for combating intersymbol interference (ISI) in frequency selective channels. We derive the general structure of the linear zero forcing (ZF) equalizing filters for multiple input multiple output (MIMO) communication systems with more outputs than inputs. These filters are finite impulse response (FIR) filters in general and their structure is determined by the number of inputs and outputs. The relation between the spatial diversity of the system and the ...

In this literature review, we have studied the evolution of multiple antenna (MA) systems, viz. SIMO (single-input-multiple-output), MISO (multiple input- single-output) and MIMO (multiple-input-multiple output) and compared the system... more

In this literature review, we have studied the evolution of multiple antenna (MA) systems,
viz. SIMO (single-input-multiple-output), MISO (multiple input- single-output) and MIMO (multiple-input-multiple output) and compared the system performance with SISO (single-input-single-output) system in terms of parameters like capacity and BER (bit error rate). The trade off between spatial multiplexing gain (which maximizes transmission rate using rich scattering) and diversity gain (which combats fading, improves reliability and minimizes probability of error) is addressed. Both transmit and receive diversities are canvassed in details. Discussion on receive diversity incorporates three most widely used schemes, viz. Selection Combining (SC), Maximal Ratio Combining (MRC) and Equal Gain Combining (EGC). Space time coding scheme is the main focus or transmit diversity study. Performance of different diversity schemes are compared both qualitatively and quantitatively. Finally we have explored how MIMO system can improve the channel capacity and the limits to which the betterment can be made under various channel conditions. The study is restricted to single user, narrow band, Rayleigh channel.

This paper proposes an efficient sub-optimal MIMO linear precoder based on the maximization of minimum distance for three virtual suchannels. A new virtual MIMO channel representation with two channel angles allows the parameterization of... more

This paper proposes an efficient sub-optimal MIMO linear precoder based on the maximization of minimum distance for three virtual suchannels. A new virtual MIMO channel representation with two channel angles allows the parameterization of the linear precoder and the optimization of the distance between signal points at the received constellation. To illustrate the optimization process, a precoder is derived for BPSK and QPSK modulation following the max-SNR approach, which consists in pouring power only on the most favored virtual sub-channel. Simulation results over a Rayleigh channel confirm the interest of this new precoder in terms of bit-error-rate.

Holography is a technique that is used to display objects or scenes in three dimensions. Such three-dimensional (3D) images, or holograms, can be seen with the unassisted eye and are very similar to how humans see the actual environment... more

Holography is a technique that is used to display objects or scenes in three dimensions. Such three-dimensional (3D) images, or holograms, can be seen with the unassisted eye and are very similar to how humans see the actual environment surrounding them. The concept of 3D telepresence, a real-time dynamic hologram depicting a scene occurring in a different location, has attracted