Multilayered space-time block codes for OFDM systems (original) (raw)
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Multilayered Space-Frequency Block Coded OFDM Systems
cspl.umd.edu
In this paper, we propose a multilayered spacefrequency block coded OFDM system, which is a combination of the vertical layered space-time architecture, known as V-BLAST, and the space-frequency block coded OFDM system. This system is designed to provide reliable as well as very high data rate communications over frequency-selective fading channels with low decoding complexity. Orthogonal Frequency Division Multiplexing (OFDM) is used to transform the frequencyselective fading channel into multiple flat fading sub-channels. Using four transmit and receive antennas at a data rate of 4 Bits/Sec/Hz, we achieve a diversity gain of about 4.5 dB over the conventional layered space-frequency coded OFDM structures (VBLAST-OFDM) at a bit error rate of 10 .
2005
We design STBC-OFDM systems with multiple-input multiple-output(MIMO) by applying several STBC schemes to the OFDM system and show their comparative analysis results obtained with the various mobile speeds, under Rayleigh fading environments, considering the effects of channel estimation error. There is no systematic comparative analysis for those STBC techniques, considering the 4th generation mobile system environments with various mobile speeds. Therefore it is very important to derive the optimum STBC-OFDM for 4G mobile system environments. We finally compare and analyze the BER performances of the STBC-OFDM systems according to the mobile speeds and the number of antennas.
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.
A Performance Study of WIMAX OFDM Includes Space-Time Block Coding
Age of wireless mobile contact is approaching rapidly. Users are increasingly demanding flexible and convenient communication modes that are accessible without losing quality and efficiency. The market for high-speed broadband infrastructure with lower energy costs. The challenge is to provide high performance, high speed, and portable customers. The response to these criteria could be that Worldwide Microwave Connectivity Interoperability (WiMAX) is a high technology that provides sub-channel services to individuals and groups. The effect of Space-Time Block Coding (STBC) on WIMAX performance is studied in this paper and compare it without STBC using Model Architecture for the WiMAX Orthogonal Frequency Division Multiplexing (OFDM) Physical Layer.
Joint BLAST-STTC for MIMO-OFDM System
Journal of information and communication convergence engineering, 2010
This study focuses on improving MIMO-OFDM systems by combining a wireless communication architecture known as vertical BLAST(bell laboratories layered space-time) or V-BLAST and STTC(space time trellis coding). In this paper, the combination is done by introducing STTC in each V-BLAST layer. Moreover, this architecture uses multiple antennas that are grouped into small number of antennas which makes it less complex to decode by decoding every group. Whereas, in traditional V-BLAST, all the antennas form one group and they are decoded together at the receiver, therefore, this increases the complexity as the number of antennas is getting high. We compare the bit error rate performance of this system with MIMO-OFDM that uses convolutional coding instead of STTC. Under the same spectral efficiency, the simulation results prove that joining V-BLAST with STTC improves MIMO-OFDM systems performance.
Int'l J. of Communications, Network and System Sciences, 2013
This work explores the performances of Space-Time and Space Frequency Coded Orthogonal Frequency Division Multiplexing (OFDM) with simple two branches transmit diversity scheme. The combination of multiple-antenna and orthogonal frequency division multiplexing (OFDM) provides reliable communications over frequency selective fading channels. We focus on the application of space-time block codes (STBC) and space-frequency block codes (SFBC) in OFDM systems over time-varying and frequency-selective channels. SFBC transmitter shows superior performance in fast varying channels while STBC shows better performance in frequency selective channels. A switching technique is presented that selects an appropriate transmission scheme between the STBC and SFBC assuming Rayleigh fading model.
IEEE Transactions on Vehicular Technology, 2006
The achievable performance of channel coded spacetime trellis (STT) codes and space-time block (STB) codes transmitted over wideband channels is studied in the context of schemes having an effective throughput of 2 bits/symbol (BPS) and 3 BPS. At high implementational complexities, the best performance was typically provided by Alamouti's unity-rate G 2 code in both the 2-BPS and 3-BPS scenarios. However, if a low complexity implementation is sought, the 3-BPS 8PSK space-time trellis code outperfoms the G 2 code. The G 2 space-time block code is also combined with symbol-by-symbol adaptive orthogonal frequency division multiplex (AOFDM) modems and turbo convolutional channel codecs for enhancing the system's performance. It was concluded that upon exploiting the diversity effect of the G 2 space-time block code, the channel-induced fading effects are mitigated, and therefore, the benefits of adaptive modulation erode. In other words, once the time-and frequency-domain fades of the wideband channel have been counteracted by the diversity-aided G 2 code, the benefits of adaptive modulation erode, and hence, it is sufficient to employ fixed-mode modems. Therefore, the low-complexity approach of mitigating the effects of fading can be viewed as employing a single-transmitter, single-receiver-based AOFDM modem. By contrast, it is sufficient to employ fixed-mode OFDM modems when the added complexity of a two-transmitter G 2 scheme is affordable.
IJERT-Performance Analysis Of Space Time Block Codes Over Rayleigh Fading Channel
International Journal of Engineering Research and Technology (IJERT), 2013
https://www.ijert.org/performance-analysis-of-space-time-block-codes-over-rayleigh-fading-channel https://www.ijert.org/research/performance-analysis-of-space-time-block-codes-over-rayleigh-fading-channel-IJERTV2IS80091.pdf To overcome the effect of multi-path fading of the channel and to achieve full diversity, the multiple antennas seems to be an efficient solution. STBC provides a new concept of transmission over Rayleigh channel using multiple transmit and receive antenna. This paper presents a detailed study of STBC scheme which includes the Alamouti's STBC for two transmitting antennas as well as orthogonal space time codes (OSTBC) for three and four transmitting antennas. Bit Error Rate (BER) performance is simulated and analyzed for different constellation schemes as BPSK, QPSK ,8-PSK and 16-QAM using MATLAB.
Low-complexity, full-diversity space-time-frequency block codes for MIMO-OFDM
IEEE Global Telecommunications Conference, 2004. GLOBECOM '04., 2004
We present a new class of Space-Time-Frequency Block Codes (STFBC) for Multiantenna Orthogonal Frequency Division Multiplexing (MIMO-OFDM) transmissions over frequency selective Rayleigh fading channels. We show that these codes admit symbol-by-symbol decoding (decoupled decoding) when the number of nonzero taps of the channel impulse response is equal to two and they admit reduced complexity (1/2 of that of known schemes) for more than two channel taps. We also present simulation results to show that our codes perform better than the known codes.
Space-time block coded OFDM with adaptive modulation and transmitter beamforming
2005
We propose an optimum transmitting structure consisting of adaptive modulation, space-time block coding (STBC), and transmitter beamforming for orthogonal frequency division multiplexing (OFDM) systems to improve the data throughput and error performance. Using correlative properties of multiinput multi-output (MIMO) channels, we maximize the channelto-noise ratio (CNR) based on a water-filling principle to optimally select the number of antenna beams and the power splitting ratio. The adaptive modulator employed is based on a lookup matrix adaptive bit and power allocation (LM-ABPA) scheme. As compared to non-adaptive systems, simulation results demonstrated that the proposed configuration achieves spectrally more efficient transmission under a constant error rate as well as better error rate performance under a constant data rate.