In this paper we investigate the performances of Decode-and-forward (DF) assisted by automatic repeat request (ARQ) relaying over Rayleigh fast fading channel. We derive a tight asymptotic approximation of the outage ...
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In this paper we investigate the performances of Decode-and-forward (DF) assisted by automatic repeat request (ARQ) relaying over Rayleigh fast fading channel. We derive a tight asymptotic approximation of the outage probability at high signal-to-noise ratio(SNR) regime. Furthermore we formulate an optimization problem aiming at achieving a target outage probability with an optimum allocation of the power budget depending on the relative position of the relay with regard to source and destination.
This paper presents the results obtained by a new multiuser detector based on the Projection Onto Convex Sets (POCS) deconvolution algorithm, in comparison with those obtained by the decorrelating detector, when the c...
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ISBN:
(纸本)9781479914180
This paper presents the results obtained by a new multiuser detector based on the Projection Onto Convex Sets (POCS) deconvolution algorithm, in comparison with those obtained by the decorrelating detector, when the channel is affected by the flat Rayleigh fading and gray images are transmitted through the system. All the users transmit their information with the same power, but the spreading codes are correlated. We will investigate the fading effect on the received images and the impact of the cross-correlation of the spreading codes on the quality of the received images. In the end, several conclusions are highlighted, with respect to the level of performance achieved.
This paper presents the theoretical derivation and system simulation of the bit error rate (BER) performance of MPSK-based coherent space-time detection and differential space-time detection over the correlated block ...
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This paper presents the theoretical derivation and system simulation of the bit error rate (BER) performance of MPSK-based coherent space-time detection and differential space-time detection over the correlated block fading channel. It provides the closed form expressions of BER for the proposed schemes. Coherent detection can obtain good BER performance, but requires reliable amplitude and phase of channel fading through the precise channel estimation. Differential detection, however, requires no channel state information, so it becomes more practical when the channel is fast-fading or the number of transmit antenna is large. Although differential detection is robust, its BER performance is inferior compared to coherent detection and has irreducible error floor in the high SNR region. Numerical results have shown that both coherent detection and differential detection get distinct diversity gain and performance of coherent detection is better than that of differential detection under the condition of the same constellation and SNR, which coincides with the theoretical results well.
OFDM (Orthogonal Frequency Division Multiplexing) can effectively eliminate the ISI between different symbols and has high frequency efficiency. OFDM is sensitive to the Doppler frequency offset caused by moving that ...
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OFDM (Orthogonal Frequency Division Multiplexing) can effectively eliminate the ISI between different symbols and has high frequency efficiency. OFDM is sensitive to the Doppler frequency offset caused by moving that can be overcome by space-timecoding. So the application the combination of the space-timecoding and OFDM in next generation wireless telecommunications has attracted more and more attention. In this article, the structure of DSTBC (Differential space-time block coding) combined with OFDM system is given first. Because of no need of channel estimation, the complexity of the receiver is simpler than STBC-OFDM system. Then, performance comparison is made by simulation among pure OFDM system, STBC-OFDM system and DSTBC-OFDM system under Rayleigh fading channel and SUI channel. It is concluded that the STBC-OFDM system can be replaced by DSTBC-OFDM system under stationary or low to moderate velocity conditions.
In this paper we propose a linear decoupling scheme for multiple-input multiple-output (MIMO) antenna systems where spatial diversity is exploited through complex orthogonal (COD) or quasi-orthogonal (CQOD) designs. T...
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In this paper we propose a linear decoupling scheme for multiple-input multiple-output (MIMO) antenna systems where spatial diversity is exploited through complex orthogonal (COD) or quasi-orthogonal (CQOD) designs. The proposed scheme is based on rewriting the space-timeblock code (STBC) in an alternative form via generalized permutation matrices (GPM) and transforming the original system to an equivalent one, where all the transmitted symbols are decoupled, allowing thus a single symbol or symbol pair-wise maximum likelihood decoding (MLD) through a closed form expression (CFE).
space-timecoding is known to be a potential technique for improving the reliability of wireless communication over fading channels. In this paper, we investigate the performance of a space-time coded CDMA system in a...
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ISBN:
(纸本)9781467373104
space-timecoding is known to be a potential technique for improving the reliability of wireless communication over fading channels. In this paper, we investigate the performance of a space-time coded CDMA system in a fading channel. Although significant amount of related work is found in literature, not much reported work exists on the use of Gold codes as spreading sequences in such systems. In this paper, we investigate the performance of a space-timeblock-coded CDMA system for different chip lengths, ranging from 31-chip to 511-chip Gold codes. Results show that at low signal-to-noise ratio, the coding gain provided by the codes surpasses the diversity advantage provided by the use of the multiple antennas. The results also show that coding gain between no-diversity link and its Gold-coded counterpart is the same as that between the transmit-diversity link and its Gold-coded counterpart. The independence of the diversity advantage provided by multiple transmit antennas and the coding gain obtainable from the use of the spreading sequences enables the prediction of the performance of composite space-timeblock-coded CDMA systems.
An optimal minimum mean square error successive interference cancellation (OMMSE SIC) scheme for Groupwise space-time block coding (G-STBC) multiple-input multiple-output (MIMO) systems is presented. In such a system,...
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An optimal minimum mean square error successive interference cancellation (OMMSE SIC) scheme for Groupwise space-time block coding (G-STBC) multiple-input multiple-output (MIMO) systems is presented. In such a system, transmit antennas are partitioned into several STBC encoding groups and each group transmits independent data stream which is individually STBC encoded. On the receiver side, by exploring the temporal constraint provided by STBC, an equivalent channel model similar to the one in standard vertical Bell laboratories layered space-time (VBLAST) systems is generated. Then OMMSE SIC algorithm is performed to detect all the transmitted *** compares the proposed scheme with non-ordering MMSE SIC scheme and the corresponding equal data rate scheme in V-BLAST systems with the same receive antennas' number. Result shows that the proposed scheme has better performance than non-ordering MMSE SIC scheme and by introducing more transmit antennas and adopting the OMMSE SIC scheme, better performance also can be achieved than corresponding V-BLAST systems.
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