Combination Of Multiple Input Multiple Output Research Articles

Modeling of Multipath Channel and Performance Analysis of MIMO‐DCO‐OFDM System in Visible Light Communications

When a big path di.erence exists between the multiple transmitter-receiver links, time dispersion is inevitable. A multipath channel model is proposed for Multiple-input multiple-output (MIMO) Visible light communications (VLC). To combat Intersymbol interference (ISI) as well as increase the channel capacity, a combination of MIMO and Direct-currentbiased Optical orthogonal frequency division multiplexing (DCO-OFDM) is studied. The performance analysis of MIMO-DCO-OFDM taking into account the limitation of the forward current of the o.-the-shelf LED is derived. The accuracy of the theoretical results is veri.ed by comparison with the Monte Carlo Bit error ratio (BER) simulation results under di.erent DC bias and di.erent clipping levels.

PAPR Reduction in STBC MIMO OFDM System using AMS and PTS Schemes

data rates and reliability are the two key factors required to support emerging multimedia applications and new communications technologies. The two techniques used in high data rate transmission are orthogonal frequency division multiplexing (OFDM) and multiple-input multiple- output (MIMO) scheme. The OFDM is used to mitigate the problem of inter symbol interference (ISI) and provides good protection against co-channel interference and noise. MIMO system helps to reduce fading and can be used for decreasing bit error rate that is spatial diversity or to increase the data rate that is spatial multiplexing. The combination of MIMO and OFDM is MIMO OFDM system. MIMO-OFDM system converts frequency selective MIMO channel into multiple parallel flat fading channels. One of the major drawbacks of in MIMO-OFDM systems is that the transmitted signal exhibits a high PAPR when the input sequences are correlated. In this paper, AMS and PTS schemes have been used to reduce peak to average power ratio (PAPR) in multiple input multiple output orthogonal frequency division multiplexing (MIMO OFDM) system with Alamouti's space time block coding (STBC). The AMS scheme reduces the computational complexity and when AMS scheme is used with quadrature amplitude modulation (QAM). Simulation and results show that the AMS scheme reduces PAPR more efficiently than the PTS scheme.

Design and study of MIMO systems studied

In this research, we are interested in a telecommunications system MIMO (multiple input multiple output) spatial multiplexing in OFDM context. ) . The objective of this work is to study and improve the transmission and reception of this MIMO (Multiple Input Multiple Output) systems technology in a multi -carrier OFDM context (Orthogonal Frequency Division Multiplex), which enables a frequency-selective channel into multiple non-selective channels. The combination of MIMO and OFDM allows exploiting the benefits of the two methods: the strength of binding on frequency-selective channels for OFDM and robustness on uncorrelated in space for the MIMO channel coding. For different configurations of multi- antenna systems SISO, SIMO and MIMO, a comparative study is made between them. This study shows that the MIMO configuration associated with the OFDM technique provides a significant performance improvement compared to other case studies. Keywords: Multiple Input Single Output ( MISO ) orthogonal frequency division multiplexing (OFDM) , Single Input Multiple Output ( SIMO ) v Single Input Single Output , Signal to Noise Ratio (SNR) , bit error rate (BER) , Multiple -Input Multiple- Output ( MIMO) .

A Next Generation Wireless Simulator Based on MIMO-OFDM: LTE Case Study

The complexity of next generation wireless systems is growing exponentially. The combination of Multiple-Input Multiple-Output (MIMO) technology with Orthogonal Frequency Division Multiplexing (OFDM) is considered as the best solution to provide high data rates under frequency-selective fading channels. The design and evaluation of MIMO-OFDM systems require a detailed analysis of a number of functionalities such as MIMO transmission modes, channel estimation, MIMO detection, channel coding, or cross-layer scheduling. In this paper we present a MIMO-OFDM-based simulator that includes the main physical and link layer functionalities. The simulator has been used to evaluate the performance of the 3GPP Long-Term Evolution (LTE) technology for different MIMO-OFDM techniques under realistic assumptions such as user mobility or bandwidth-limited feedback channel.

Proposal of Receive Antenna Selection Methods for MIMO-OFDM System

The combination of Multiple-Input Multiple-Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) technologies gives wireless communications systems the advantages of lower bit error rate (BER) and higher data rate in frequency-selective fading environments. However, the main drawbacks of MIMO systems are their high complexity and high cost. Therefore, antenna selection in MIMO systems has been shown to be an effective way to overcome the drawbacks. In this paper, we propose two receive antenna selection methods for a MIMO-OFDM system with radio frequency (RF) switches and polarization antenna elements at the receiver side, taking into consideration low computational complexity. The first method selects a set of polarization antenna elements which gives lower correlation between received signals and larger received signal power, thus achieves a lower BER with low computational complexity. The second method first selects a set of polarization antenna elements based on the criterion of the first method and another set of polarization antenna elements based on the criterion of minimizing the correlation between the received signals; it then calculates the signal-to-interference-plus-noise power ratio (SINR) of the two sets and selects a set with larger SINR. As a result, the second method achieves a better BER than the first one but it also requires higher computational complexity than the first one. We use the measured channel data to evaluate the performance of the two methods and show that they work effectively for the realistic channel.