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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
Multipath Diversity Of Precoded Ofdm With Linear Equalization, Xiaojing Huang
Multipath Diversity Of Precoded Ofdm With Linear Equalization, Xiaojing Huang
Faculty of Informatics - Papers (Archive)
This paper settles a controversy over the multipath diversity performance of the precoded orthogonal frequency division multiplexing system with the linear equalization. Through the asymptotical analysis of the bit error rates with extreme system parameters, a comprehensive understanding of the linear equalization's behavior in the frequency-selective multipath fading channels is gained. Compared with the optimum maximum-likelihood detection, the diversity performance of the linear equalization can be well described by an asymptotical signal-to-noise ratio (SNR) degradation, which reveals that the linear equalization can achieve the maximum multipath diversity within an operational SNR range but will lose diversity advantage as SNR increases.
On The Use Of Quasi-Orthogonal Space-Time-Frequency Codes In Mb-Ofdm Uwb, Le Chung Tran, Alfred Mertins
On The Use Of Quasi-Orthogonal Space-Time-Frequency Codes In Mb-Ofdm Uwb, Le Chung Tran, Alfred Mertins
Faculty of Informatics - Papers (Archive)
Space-Time-Frequency Codes (STFCs), which haverecently been proposed in the literature for Multiband OFDMUltra-Wideband (MB-OFDM UWB) systems to improve thesystem capacity, error performance and wireless communicationrange, are all constructed based on orthogonal structures. Thispaper examines the application of Quasi-Orthogonal STFCs(QOSTFCs) to enhance further either data rate or error performancein the recently proposed STFC MB-OFDM UWB systems.It will be shown that QOSTFCs can provide significantly bettererror performance, compared to the conventional MB-OFDMUWB (without STFCs) as well as to the Orthogonal STFCs(OSTFCs) of the same order, at the same data rate, withoutincreasing the total transmission power. Equivalently, QOSTFCscan provide higher data rates with …
Higher Order Parallel Concatenated Spreading Matrices Ofdm, Xiaojing Huang, Ibrahim Raad
Higher Order Parallel Concatenated Spreading Matrices Ofdm, Xiaojing Huang, Ibrahim Raad
Faculty of Informatics - Papers (Archive)
This paper studies higher order parallel concatenated spreading matrix OFDM (PCSM-OFDM). PCSM-OFDM was shown to greatly improve on the classic Block Spread OFDM, this paper continues the work on PCSM-OFDM and studies higher order in terms of an increased number of streams. This shows that with the increase in the streams the overall BER performance improves.
A Study Of Different Angles For Higher Order Rotation Spreading Matrix For Bsofdm In Uwb Channels, Ibrahim S. Raad, Xiaojing Huang, R. Raad
A Study Of Different Angles For Higher Order Rotation Spreading Matrix For Bsofdm In Uwb Channels, Ibrahim S. Raad, Xiaojing Huang, R. Raad
Faculty of Informatics - Papers (Archive)
This paper presents a study into different angles for higher order Rotation spreading matrix developed for BSOFDM. It was shown previously that for block size M = 2 that the angle α = π/3 achieved the best result in terms of BER in UWB channels. It was discovered that this was no longer the case when the higher order Rotation spreading matrix was used for larger M sized blocks and that other angles produced better results which proves that the Rotation spreading matrix advantage over existing spreading matrices such as the Hadamard is its flexibility to be adapted to different …
Stc-Mimo Block Spread Ofdm In Frequency Selective Rayleigh Fading Channels, Le Chung Tran, Xiaojing Huang, Eryk Dutkiewicz, Joe F. Chicharo
Stc-Mimo Block Spread Ofdm In Frequency Selective Rayleigh Fading Channels, Le Chung Tran, Xiaojing Huang, Eryk Dutkiewicz, Joe F. Chicharo
Faculty of Informatics - Papers (Archive)
In this paper, we expand the idea of spreading the transmitted symbols in OFDM systems by unitary spreading matrices based on the rotated Hadamard or rotated Discrete Fourier Transform (DFT) matrices proposed in the literature to apply to Space-Time Coded Multiple-Input Multiple-Output OFDM (STC-MIMO-OFDM) systems. We refer the resulting systems to as STC-MIMO Block Spread OFDM (STC-MIMO-BOFDM) systems. In the proposed systems, a multi-dimensional diversity, including time, frequency, space and modulation diversities, can be used, resulting in better bit error performance in frequency selective Rayleigh fading channels compared to the conventional OFDM systems with or without STCs. Simulations carried out …
Decision Aided Joint Compensation Of Clipping Noise And Nonlinearity For Mimo-Ofdm Systems, Shouyi Yang, Jiangtao Xi, Xiaomin Mu
Decision Aided Joint Compensation Of Clipping Noise And Nonlinearity For Mimo-Ofdm Systems, Shouyi Yang, Jiangtao Xi, Xiaomin Mu
Faculty of Informatics - Papers (Archive)
In this paper, we propose a new iterative approach to compensate the nonlinearity and clipping noise in multi-input multi-output orthogonal frequency division multiplexing (MlMO-OFDM) system with nonlinear channel. The proposed approach consists of two stages. Firstly a decision aided method is proposed to eliminate the nonlinearity introduced by high power transmit amplifier (HPA). Then this improved decision observations are employed to achieve the clipping noise compensation. The effectiveness of the proposed approach has been verified by computer simulations.
An Adaptive Scalable Multiuser-Ofdm System For Multimedia Transmission Over Fading Channels, Ahmed Muthana M. Nadhim, Jianhua He, Jiangtao Xi, Zongkai Yang
An Adaptive Scalable Multiuser-Ofdm System For Multimedia Transmission Over Fading Channels, Ahmed Muthana M. Nadhim, Jianhua He, Jiangtao Xi, Zongkai Yang
Faculty of Informatics - Papers (Archive)
In this paper, an adaptive scalable multiuser-OFDM system was proposed for multimedia transmission over fading channels. The proposed adaptive algorithm can adapt according to the channel status information of each user's channel status. This algorithm dynamically changes according to the user's channel changes; this can keep fixed QoS at the physical layer. Another predefined QoS for different sessions and services to be provided for different users. This QoS can be guaranteed by multimedia scalability. Scalability can adapt to the service requirements, in terms of transmission data rate and bandwidth. As a result, a robust multimedia transmission scheme is achieved by …