Experimental studies on optimal space-frequency codes for MIMO-OFDM systems (original) (raw)
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IJERT-A Study on Space Time/Frequency Block Codes for MIMO OFDM System
International Journal of Engineering Research and Technology (IJERT), 2014
https://www.ijert.org/a-study-on-space-timefrequency-block-codes-for-mimo-ofdm-system https://www.ijert.org/research/a-study-on-space-timefrequency-block-codes-for-mimo-ofdm-system-IJERTV1IS7265.pdf Now a days, wireless communication is used worldwide. For larger capacity and higher data rate there is a need of multiple antenna at the transmitter and the receiver. So we use MIMO system. As the data rate is increasing in transmission system there occur some problems also with wireless communication. These are inter-carrier interference, multipath fading. To combat these problems we use OFDM. OFDM is an Orthogonal Frequency Division Multiplexing technique having great intensity to enhance the performance of wireless communication system.
Low Complexity Space-Frequency MIMO OFDM System for Double-Selective Fading Channels
This paper presents a highly robust space-frequency block coded (SFBC) multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system. The proposed system is based on applying a short block length Walsh Hadamard transform (WHT) after the SFBC encoder. The main advantage of the proposed system is that the channel frequency responses over every two adjacent subcarriers become equal. Such interesting result provides an exceptional operating conditions for SFBC-OFDM systems transmitting over time and frequencyselective fading channels. Monte Carlo simulation is used to evaluate the bit error rate (BER) performance of the proposed system using various wireless channels with different degrees of frequency selectivity and Doppler spreads. The simulation results demonstrated that the proposed scheme substantially outperforms the standard SFBC-OFDM and the space-time block coded (STBC) OFDM systems in severe time-varying frequency-selective fading channels. Mo...
Performance Enhancement of MIMO OFDM for Higher Spectral Efficiency
The Multiple-Input Multiple-Output based wireless system is a promising high data rate interface technology. Diversity methods provide the receiver with independently faded copies of the transmitted signal with the expectation that at least one of these replicas will be received data. This is ranges of techniques available through which these faded copies can be recovered and used as part of arrangements. This paper proposes a method based on Multiple-Input Single-Output (MISO) with Space-Time Block Coding (STBC) and Multiple-Input Multiple-Output (MIMO) set-up for use in wireless channels. A special of STBC called Alamouti code is used for exploiting in the performance of MISO and MIMO in frequency selective fading environment. The observed with and without STBC in frequency selective faded channels. The diversity gain of MISO and MIMO systems in terms of BER for High QAM modulation scheme. The obtained results demonstrate that spatial diversity along with the power of STBC significantly improves the error performance in frequency selective wireless fading channels. These techniques offer a significant gain over a traditional single input single output (SISO) channel.
A New Full-Diversity Space-Time-Frequency Block Code for MIMO-OFDM System
2013
Multi-input multi-output-orthogonal frequency-division multiplexing (MIMO-OFDM) is known as a proper solution for wideband wireless communication. Numerous space-frequency block codes (SFBCs) and space-time-frequency block codes (STFBCs) have been proposed so far for implementing MIMO-OFDM systems. In this paper, a new full-diversity STFBC is proposed for two transmit antennas, which could benefit from the maximum coding advantage when delay and power profiles (DPPs) of the channel are available at the transmitter. Furthermore, simulation results confirm that the proposed STFBC outperforms other recently proposed STFBCs with the same order of the receiver complexity.
Review of space time coded OFDM system for wireless communication
IETE Technical Review
Deployment of multi-input multi-output antenna systems with orthogonal frequency division multiplexing (OFDM) over wireless channels has been identified as one of the most promising techniques to support high-performance and high data rate communication for future wireless broadband services. This paper first highlights common space-time coding (STC) schemes used in wireless communication systems. The paper further reviews the deployments of these STC schemes over frequency selective fading channels with OFDM signalling through which there is coding over the space, time, and frequency domains.
This paper proposes a space-frequency (SF) coding scheme for non-coherent (NC) Multiple Input Multiple Output (MIMO)-Orthogonal Frequency Division Multiplexing (OFDM) fading links, where neither the transmitter nor the receiver knows the channel. Our strategy consists in applying a convolutional encoder and an interleaver before applying a SF encoder. This SF encoder distributes the encoded and interleaved bits over the different OFDM symbols. In order to reduce the decoding complexity, each OFDM symbol is divided into several groups. Within each group, the obtained bits are broken into two substreams. The first substream is used to construct a systematic NC codeword which leads to a simple decoding rule over the multipath channel. The second subtream is mapped to a Grassmannian NC codeword obtained via an exponential map and that was proposed for NC space-time (ST) coding based system and has the advantage of using all the degrees of freedom of this system. We show through asymptotic Pairwise Error Probability (PEP) analysis and simulation results that our encoding strategy can provide full diversity gain and achieves better performance in terms of spectrum efficiency and bit error rate than both the systematic NC-SF coding and our proposed SF coding without convolutional encoding and interleaving.
We are going to implement and study a space frequency coded OFDM system which consists of two transmitters and a single receiver. Simple Alamouti spacetime code is used. An M-ary PSK modulation is used to modulate the symbols across an OFDM channel. We will also propose a variation of the scheme which tries to spread additional symbols across time-frequency attempting to increase the rate of transmission without changing the type of modulation employed or increasing bandwidth. A Rayleigh frequency selective slow fading channel is assumed throughout the analysis. SER performance of the above systems is carried-out with emphasis on the modulation scheme, no. of carriers and bit SNR.
Space-time-frequency (STF) coding for MIMO-OFDM systems
IEEE Communications Letters, 2000
We consider the capacity of multiple-input-multiple-output (MIMO) systems that use OFDM as the modulation format. We point out a basic equivalence between antennas and OFDM-tones. This similarity immediately allows us to essentially reuse all space-time codes designed for flat-fading channels in MIMO-OFDM systems operating in frequency-selective channels. An optimum code would thus code across all antennas and tones (as well as time) simultaneously. Since this can become very complex, we propose a method for grouping antennas and codes in such a way that the inherent diversity is retained, while the complexity is greatly reduced. Capacity computations between the full-complexity and the reduced-complexity systems illustrate this tradeoff.
Performance of space-frequency codes in MIMO channels with frequency offset
Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, 2004., 2004
We investigate the pair-wise error probability (PEP) performance of space-frequency (SF) codes over quasi-static, frequency-selective Rayleigh fading channels with frequency offset (FO). The PEP expression shows that the conventional SF code design criteria are remained valid. If the normalized FO (NFO) is less than 1%, the performance loss is negligible.