Space-time coding for UMTS. Performance evaluation in combination with convolutional and turbo coding

Space-time codes provide both diversity and coding gain when using multiple transmit antennas to increase spectral efficiency over wireless communications systems. Space-time block codes have already been included in the standardization process of UMTS in conjunction with conventional channel codes (convolutional and turbo codes). We discuss different encoding and decoding strategies when transmit diversity is combined with conventional channel codes, and present simulations results for the TDD and FDD modes of UTRA.Peer ReviewedPostprint (published version

Using Hierarchical Data Mining to Characterize Performance of Wireless System Configurations

This paper presents a statistical framework for assessing wireless systems performance using hierarchical data mining techniques. We consider WCDMA (wideband code division multiple access) systems with two-branch STTD (space time transmit diversity) and 1/2 rate convolutional coding (forward error correction codes). Monte Carlo simulation estimates the bit error probability (BEP) of the system across a wide range of signal-to-noise ratios (SNRs). A performance database of simulation runs is collected over a targeted space of system configurations. This database is then mined to obtain regions of the configuration space that exhibit acceptable average performance. The shape of the mined regions illustrates the joint influence of configuration parameters on system performance. The role of data mining in this application is to provide explainable and statistically valid design conclusions. The research issue is to define statistically meaningful aggregation of data in a manner that permits efficient and effective data mining algorithms. We achieve a good compromise between these goals and help establish the applicability of data mining for characterizing wireless systems performance

Performance Analysis of Two-Hop Cooperative MIMO transmission with Relay Selection in Rayleigh Fading Channel

Wireless relaying is one of the promising solutions to overcome the channel impairments and provide high data rate coverage that appears for beyond 3G mobile communications. In this paper we present an end to end BER performance analysis of dual hop wireless communication systems equipped with multiple decode and forward relays over the Rayleigh fading channel with relay selection. We select the best relay based on end to end channel conditions. We apply orthogonal space time block coding (OSTBC) at source, and also present how the multiple antennas at the source terminal affects the end to end BER performance. This intermediate relay technique will cover long distance where destination is out of reach from source.Comment: 5 figures, 4th International Conference on Wireless Communications, Networking and Mobile Computing, 2008. WiCOM '0

Space-time codes for wireless communication

With an increasing demand for high data rate, there has been a lot of research in the field of wireless communication. This paper deals with the fundamentals of space-time coding for wireless communication systems. A well-known technique known as Space]Time Coding has been adopted in the systems using multiple antennas for high speed and reliable communication. The basic idea of space-time coding deals with the designing of two-dimensional signal matrix that is to be transmitted over an interval of time from a number of transmitting antennas. High data rate and improved bit error performance can be achieved by exploiting diversity in the spatial dimensions by designing appropriate signal structure. Space-Time Block Coding is a MIMO transmit strategy which exploits transmit diversity and high reliability. We analyze the basic design structure of the space- time codes and summarize their relative performances

Performance Evaluation of Space-Time Codes Applying OFDM in Mobile Wireless Communicaton

Recently the rapid growth of wireless voice subscribers, the growth of the internet and the increasing use of portable computing devices suggest that wireless internet access will rise rapidly over the next few years. Wireless internet is demanded to increase the channel capacity and data rate. It is difficult to increase the channel capacity or reducing the effective error rate in a multipaths fading channel. To solve the above problems in wireless communications, Tarokh et al. introduced space -time codes adopting a joint design of coding, modulation, and transmit diversity. Space-time coding introduces temporal and spatial correlation into signals transmitted from different antennas, in order to provide diversity at the receiver, and coding gain over an uncoded system without sacrificing the bandwidth. The spatial-temporal structure of these codes can be exploited to increase further the capacity of wireless systems with a relatively simple receiver structure. Simulation results show that at the frame error rate of the 32-state code with two receiver antennas gives about 3dB gain over the use of a 4 states and two receiver antennas with the 32-state code give about 6 dB gain over the use of one receiver antenna. It appears from the simulation results that the coding advantage obtained by increasing the number of states and diversity gain obtained by increasing the number of receive antenna. This thesis also studies space-time codes applying orthogonal frequency division multiplexing (OFDM) systems in wireless communication. In OFDM, the entire channel is divided into many narrow parallel subchannels, thereby increasing the symbol duration and reducing or eliminating the intersymbol interference (ISI) caused by the multipath environments. At the frame error rate of 10^-1 the 32-state code with space-time codes applying OFDM gives about 7dB gain over the use of the 4-state code by simulation. Therefore, space-time codes applying OFDM systems can be used for highly efficient data transmission over mobile wireless channels.목차 Nomenclature = ii Abstract = iii 제1장 서론 = 1 제2장 시공간 부호의 부복호 방식 = 3 2.1 시공간 부호의 기본 개념 = 3 2.2 시공간 트렐리스 부호 = 11 2.3 시공간 블록 부호 = 17 제3장 시공간 부호를 적용한 OFDM 시스템 = 24 3.1 시공간 트렐리스 부호의 복호 방식 제안 = 24 3.2 OFDM 기본 원리 및 시스템 구성 = 27 3.3 OFDM을 적용한 시공간 트렐리스 부호 = 30 3.4 OFDM을 적용한 시공간 블록 부호 = 32 제4장 시뮬레이션에 의한 시공간 부호의 성능 분석 = 34 4.1 OFDM을 적용하지 않은 경우 = 34 4.2 OFDM을 적용한 경우 = 37 제5장 결론 = 39 참고문헌 = 4

Super-orthogonal space-time turbo coded OFDM systems.

Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2012.The ever increasing demand for fast and efficient broadband wireless communication services requires future broadband communication systems to provide a high data rate, robust performance and low complexity within the limited available electromagnetic spectrum. One of the identified, most-promising techniques to support high performance and high data rate communication for future wireless broadband services is the deployment of multi-input multi-output (MIMO) antenna systems with orthogonal frequency division multiplexing (OFDM). The combination of MIMO and OFDM techniques guarantees a much more reliable and robust transmission over a hostile wireless channel through coding over the space, time and frequency domains. In this thesis, two full-rate space-time coded OFDM systems are proposed. The first one, designed for two transmit antennas, is called extended super-orthogonal space-time trellis coded OFDM (ESOSTTC-OFDM), and is based on constellation rotation. The second one, called super-quasi-orthogonal space-time trellis coded OFDM (SQOSTTCOFDM), combines a quasi-orthogonal space-time block code with a trellis code to provide a full-rate code for four transmit antennas. The designed space-time coded MIMO-OFDM systems achieve a high diversity order with high coding gain by exploiting the diversity advantage of frequency-selective fading channels. Concatenated codes have been shown to be an effective technique of achieving reliable communication close to the Shannon limit, provided that there is sufficient available diversity. In a bid to improve the performance of the super orthogonal space-time trellis code (SOSTTC) in frequency selective fading channels, five distinct concatenated codes are proposed for MIMO-OFDM over frequency-selective fading channels in the second part of this thesis. Four of the coding schemes are based on the concatenation of convolutional coding, interleaving, and space-time coding, along multiple-transmitter diversity systems, while the fifth coding scheme is based on the concatenation of two space-time codes and interleaving. The proposed concatenated Super-Orthogonal Space-Time Turbo-Coded OFDM System I. B. Oluwafemi 2012 vii coding schemes in MIMO-OFDM systems achieve high diversity gain by exploiting available diversity resources of frequency-selective fading channels and achieve a high coding gain through concatenations by employing the turbo principle. Using computer software simulations, the performance of the concatenated SOSTTC-OFDM schemes is compared with those of concatenated space-time trellis codes and those of conventional SOSTTC-OFDM schemes in frequency-selective fading channels. Simulation results show that the concatenated SOSTTC-OFDM system outperformed the concatenated space-time trellis codes and the conventional SOSTTC-OFDM system under the various channel scenarios in terms of both diversity order and coding gain

Transmission of compressed multimedia data over wireless channels using space-time OFDM with adaptive beamforming

The transmission of multimedia data over wireless channels poses significant constraints on the communication system bandwidth, energy, and latency. To overcome these bottlenecks to wireless multimedia communication, various channel coding and transmit diversity schemes have been proposed. In previous work, we have shown that space-time block-coding (STBC) with adaptive beamforming (STBC-OFDM-AB) is an effective technique for improving the error-rate performance and channel capacity of wireless multimedia systems utilizing OFDM. In this paper, we introduce a transmission system for multimedia communication employing STBC-OFDM with adaptive beamforming incorporating a perceptually-based image compression coder - which consists of a 2-D discrete wavelet transform (DWT), an adaptive quantizer (with thresholding) and variable-length entropy encoding. Initial simulation results based on the transmission of compressed images, showed that the performance improvement introduced by STBC-OFDM-AB can be readily observed, and compared to other transmission methods is better suited to wireless multimedia communication

Design and Implementation of Distributed Space-Frequency to Achieve Cooperative Diversity in Wireless Relay Networks

Recently, there has been much interest in modulation techniques that can help in achieving transmit diversity motivated by the increased capacity of multiple-input multiple- output (MIMO) channel. To achieve transmit diversity the transmitter needs to be equipped with multiple antennas. The antennas should be well separated to have uncorrelated fading among the different antennas. This results in higher diversity orders and higher coding gains. However, achieving transmit diversity for mobile units requires cooperative diversity. In this context, the space-time codes (STC) for spread spectrum CDMA systems have received great interest in recent times. The schemes presented in this paper ensure that the limitations of conventional correlation receivers are overcome. The effect of the space-time code distribution on the space-time code that achieves full diversity with maximum coding gain over MIMO channels is studied in this paper. In most of the analogous works surveyed so far, it is observed, that, there has been very little focus on the study of systems that exhibit diversity of all the three forms namely: source coding diversity, channel coding diversity and user cooperation diversity. However, in this paper, all these three forms of diversity are uniformly considered and the proposed schemes are studied for their robustness and performance. It is shown, that, the proposed space-time coded communication scheme is both bandwidth and power efficient. To analyze the proposed scheme fully, communication over fading channels is considered. The maximum-likelihood decision metric is used to decode the original information in the presence of channel estimation errors. A study of the performance of the proposed STC system in the presence of slowly changing Rayleigh channels is also presented. Keywords: Multipath fading, Communication systems, Distributed Space-time codes, Wireless relay networks, Signal Processing, Multinode Cooperative communication, multiple sensor detection system

Performance of multiple-input multiple-output wireless communications systems using distributed antennas

In this contribution we propose and investigate a multiple-input multiple-output (MIMO) wireless communications system, where multiple receive antennas are distributed in the area covered by a cellular cell and connected with the base-station (BS). We first analyze the total received power by the BS through the distributed antennas, when assuming that the mobile's signal is transmitted over lognormal shadowed Rayleigh fading channels. Then, the outage probability of the distributed antenna MIMO systems is investigated, when considering various antenna distribution patterns. Furthermore, space-time coding at the mobile transmitter is considered for enhancing the outage performance of the distributed antenna MIMO system. Our study and simulation results show that the outage performance of a distributed antenna MIMO system can be significantly improved, when either increasing the number of distributed receive antennas or increasing the number of mobile transmit antennas