In this paper, the performance analysis of MIMO systems with arbitrary number transmit antenna selection(TAS) and orthogonal space-time block coding(STBC) in Rayleigh fading channels for imperfect channel state inform...
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In this paper, the performance analysis of MIMO systems with arbitrary number transmit antenna selection(TAS) and orthogonal space-time block coding(STBC) in Rayleigh fading channels for imperfect channel state information(CSI) is presented. For the performance analysis, the moment generating function of the system effective SNR as well as its upper and lower bounds are derived. Then, accurate and approximate expressions of bit error rate(BER) of MIMO-TAS-STBC with MPSK and MQAM are further derived. Using the approximate BER formula and imperfect CSI, an adaptive antenna selection scheme is developed for minimizing the BER. The diversity gain and coding gain are analyzed at high SNR. The results indicate that the MIMOTAS-STBC for imperfect CSI can only achieve partial diversity order K N and the coding gain is affected by K,N, code rate, modulation pattern, and channel correlation coefficients, when K transmit antennas are selected and N receive antennas are used. Simulation results show that the theoretical analysis matches the simulation result well, and the approximate expressions are close to the accurate ones but have a lower complexity.
A radio-over-fiber distributed antenna system permits larger physical separation between antennas in a wireless system's infrastructure;this investigation verifies that improved performance-lower error rates and h...
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A radio-over-fiber distributed antenna system permits larger physical separation between antennas in a wireless system's infrastructure;this investigation verifies that improved performance-lower error rates and higher capacities-can thus be achieved. In this paper, specific single-input multiple-output (SIMO), multiple-input single-output (MISO), and multiple-input multiple-output (MIMO) algorithms are compared in an experimental radio over fiber system, using user-defined processing functions for the signals. It is shown that significantly reduced symbol error rate (SER) and modestly increased capacity is achieved for a wireless 1 x 2 SIMO uplink using the maximal ratio combining processing algorithm and 2 x 1 MISO downlink using the Alamouti spacetimeblockcoding scheme. Further, SER is reduced for a downlink 2 x 2 wireless MIMO using the zero-forcing algorithm while, most importantly, greatly increased capacity is achieved through the spatial multiplexing gain.
In this study, an overlay spectrum sharing scheme has been proposed for a cognitive radio system. To achieve the desired quality of service for the licenced (i.e. primary) system and spectrum access for unlicenced (i....
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In this study, an overlay spectrum sharing scheme has been proposed for a cognitive radio system. To achieve the desired quality of service for the licenced (i.e. primary) system and spectrum access for unlicenced (i.e. secondary) system, a three-phase cooperative decode and forward relaying is used. Furthermore, space-time block coding is used in order to cancel the interference at primary as well as secondary receiver. It has been shown that the proposed scheme helps in achieving diversity gain of three and two for primary and secondary systems, respectively. The performance of both primary and cognitive (secondary) system is appraised by deriving closed-form expression for bit error rate and outage probability. The theoretical and simulation results validate that the proposed scheme improves the performance of both systems as compared with the earlier proposed schemes.
In this paper, an iterative robust minimum-mean square error (MMSE) receiver for space-time block coding (STBC) is proposed to mitigate the performance degradations caused by channel state information (CSI) errors. Th...
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In this paper, an iterative robust minimum-mean square error (MMSE) receiver for space-time block coding (STBC) is proposed to mitigate the performance degradations caused by channel state information (CSI) errors. The proposed scheme estimates an instantaneous covariance matrix of the effective noise, which includes additive white Gaussian noise and the effect of CSI errors. For this estimation, multiple solution candidate vectors are selected based on the distances between the MMSE estimate of the solution and the constellation points, and their a-posteriori probabilities are utilized to execute the estimation of the covariance matrix. To improve the estimation accuracy, the estimated covariance matrix is updated iteratively. Simulation results show that proposed robust receiver achieves substantial performance gains in terms of bit error rates as compared to conventional receiver schemes under CSI errors.
A combination of space-time block coding and spatial modulation (STBC-SM) has been recently proposed for multiple input-multiple output systems to obtain both spatial diversity gain and more capacity simultaneously wh...
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A combination of space-time block coding and spatial modulation (STBC-SM) has been recently proposed for multiple input-multiple output systems to obtain both spatial diversity gain and more capacity simultaneously while assuming the perfect channel state information (P-CSI) was available at the receiver. However, in practical scenarios the CSI is unknown to the receiver and should be estimated in order to detect the transmitted data in a reliable way. Therefore, channel estimation (CE) is a major challenge in designing the STBC-SM systems. In this study, the problem of CE is investigated and a new pilot-aided channel estimation (PA-CE) technique, coupled with an interpolation, is proposed for the STBC-SM systems operating in the presence of rapidly time-varying mobile channels. Several interpolation schemes such as the linear, nearest neighbour, piecewise cubic Hermite and the low-pass interpolations are applied and their performances are compared to determine the best suitable interpolation technique to be employed in STBC-SM systems. Bit error rate (BER) performance of the proposed CE technique is then investigated in time-varying channels with different modulation. Moreover, the pairwise error probability of the STBC-SM scheme is derived and its average bit error probability is evaluated analytically in the presence of CE errors.
Application Layer Forward Error Correction (AL-FEC) based on Raptor codes has been employed in Multimedia Broadcast/Multicast Services (MBMS) to improve reliability. This paper considers a cross-layer system based on ...
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ISBN:
(纸本)9781509017010
Application Layer Forward Error Correction (AL-FEC) based on Raptor codes has been employed in Multimedia Broadcast/Multicast Services (MBMS) to improve reliability. This paper considers a cross-layer system based on the latest Raptor Q codes for transmitting high data rate video. Multiple Input Multiple Output (MIMO) channels in a realistic outdoor environment for a user moving at 50kmph in an LTE-A system is considered. A link adaptation model with optimized cross-layer parameters is proposed under different channel conditions and quality of service requirements. The system investigates throughput performance for Spatial timeblockcoding (STBC) and Spatial Multiplexing (SM) MIMO with and without raptor codes. Improvements of up to 4dB SNR are seen by using raptor codes with SM depending upon the channel conditions and chosen Modulation and coding Scheme (MCS). Results also show that at low SNR and low spatial correlation, the performance of AL-FEC with SM is better than STBC even when the user is moving at high speeds.
In this paper, we present a practical simple location-aided umbrella-shaped beamforming scheme with transmit diversity of massive Multiple-input Multiple-output (MIMO) system for high speed railway scenarios. Unlike c...
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ISBN:
(纸本)9781509016983
In this paper, we present a practical simple location-aided umbrella-shaped beamforming scheme with transmit diversity of massive Multiple-input Multiple-output (MIMO) system for high speed railway scenarios. Unlike conventional schemes which combines space-time block coding (STBC) with adaptive beamforming or orthogonal switched beamforming, our scheme needs neither uplink channel covariance matrix (UCCM) nor downlink CCM (DCCM) but precalculates the beamforming weights with the help of train location information, which can be completed through pure off-line calculation and therefore reduce system implementation complexity. A closed-form solution of power allocation optimization is derived and the performance of our scheme is verified with simulations from the perspectives of instantaneous received signal-to-noise ratio (SNR), bit error rate (BER) and handover success probability. It indicates that the performance of our scheme approaches to the combination scheme of STBC and adaptive beamforming (STBC-ABF) without introducing any on-line system complexities.
In this paper, we consider a multi-relay cooperative network assisted by the Automatic Repeat reQuest mechanism. In particular, the source node broadcasts the encoded stream to a set of relaying nodes and a relay will...
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ISBN:
(纸本)9781509051465
In this paper, we consider a multi-relay cooperative network assisted by the Automatic Repeat reQuest mechanism. In particular, the source node broadcasts the encoded stream to a set of relaying nodes and a relay will be chosen at each retransmission round to assist the source to convey the same stream to the common destination. Afterwards, we develop a semi-analytical method to compute the exact end-to-end outage probability, average delay and throughput metrics for the general case where the relays are positioned at various locations. This analytical method is corroborated by extensive simulation results to prove the accuracy of the proposed formulation. Further, we assess the performance of several relay-placement and power allocation configurations to find the optimal scheme.
We introduce the concept of space-time Super-Modulation according to which additional low rate and highly reliable information can be transmitted by further super-modulating blocks of traditionally modulated and space...
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ISBN:
(纸本)9781509013296
We introduce the concept of space-time Super-Modulation according to which additional low rate and highly reliable information can be transmitted by further super-modulating blocks of traditionally modulated and space-time encoded information. This is achieved by exploiting the redundant information introduced by the space-timeblock codes and, specifically, by efficiently mapping transmission patterns to specific information content. It is shown that space-time Super-Modulation can be efficiently used in the context of machine-type communications to enable joint medium access and rateless data transmission while minimizing or even eliminating the need for transmitting preamble sequences. Compared with traditional approaches that use encoded preambles or preambles based on Zadoff-Chu sequences to transmit the signature information of transmitted packets, space-time Super-Modulation can achieve throughput gains of more than 35% when transmitting blocks of 200 symbols.
In this paper, we propose a transmit multi-block frequency-domain equalization (MB-FDE) for frequency-domain space-timeblock coded joint transmit/receive diversity (FD-STBC-JTRD). Noting that a STBC codeword consists...
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In this paper, we propose a transmit multi-block frequency-domain equalization (MB-FDE) for frequency-domain space-timeblock coded joint transmit/receive diversity (FD-STBC-JTRD). Noting that a STBC codeword consists of multiple coded blocks, the transmit MB-FDE uses the multiple transmit FDE weight matrices, each associated with each coded block. Both single-carrier (SC) transmission and orthogonal frequency-division multiplexing (OFDM) transmission are considered. For SC transmission, the transmit MB-FDE weight matrices are jointly optimized so as to minimize the mean square error (MSE) between the transmit signal before STBC encoding and the received signal after STBC decoding. For OFDM transmission, they are jointly optimized so as to maximize the received signal-to-noise power ratio (SNR) after STBC decoding. We show by theoretical analysis that the proposed transmit MB-FDE can achieve 1/R-STBC times higher received SNR than the conventional transmit single-block FDE (SB-FDE), where R-STBC represents the code rate of STBC. It is confirmed by computer simulation that, when more than 2 receive antennas are used, MB-FDE can always achieve better BER performance than SB-FDE irrespective of the number of transmit antennas, and the channel frequency-selectivity.
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