To overcome the overhead involved with channel estimation, several non-coherent distributed space-time coding (DSTC) strategies for two-way wireless relay networks (TWRNs) using the amplify-and-forward and the decode-...
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To overcome the overhead involved with channel estimation, several non-coherent distributed space-time coding (DSTC) strategies for two-way wireless relay networks (TWRNs) using the amplify-and-forward and the decode-and-forward protocol have been recently proposed that do not require channel state information (CSI) at any node to decode the information symbols. In this paper, novel differential DSTC strategies for TWRNs using the two- and three-phase protocol are proposed. In our transmission schemes, the relays do not waste power to transmit information known at the respective destination nodes. This is achieved by combining the symbols from both terminals received at the relays into a single symbol of the unaltered constellation. Furthermore, in our strategies, the direct link between the communicating terminals can be naturally incorporated to further improve the diversity gain. Simulations show a substantially improved performance in terms of bit error rate (BER) of the proposed strategies as compared to the existing strategies. (C) 2012 Elsevier B.V. All rights reserved.
Adaptive power allocation (PA) algorithms with different criteria for a cooperative multiple-input multiple-output network equipped with distributed space-time coding are proposed and evaluated. Joint constrained opti...
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Adaptive power allocation (PA) algorithms with different criteria for a cooperative multiple-input multiple-output network equipped with distributed space-time coding are proposed and evaluated. Joint constrained optimisation algorithms to determine the PA parameters and the receive filter are proposed for each transmitted symbol in each link, as well as the channel coefficients matrix. Linear receive filter and maximum-likelihood detection are considered with amplify-and-forward and decode-and-forward cooperation strategies. In these proposed algorithms, the elements in the PA matrices are optimised at the destination node and then transmitted back to the relay nodes via a feedback channel. The effects of the feedback errors are considered. Linear minimum mean square error expressions and the PA matrices depend on each other and are updated iteratively. Stochastic gradient algorithms are developed with reduced computational complexity. Simulation results show that the proposed algorithms obtain significant performance gains as compared with existing PA schemes.
Mobile users with single antennas can still take advantage of spatial diversity through cooperative space-time encoded transmission. In this paper, we consider a scheme in which a relay chooses to cooperate only if it...
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Mobile users with single antennas can still take advantage of spatial diversity through cooperative space-time encoded transmission. In this paper, we consider a scheme in which a relay chooses to cooperate only if its source-relay channel is of an acceptable quality and we evaluate the usefulness of relaying when the source acts blindly and ignores the decision of the relays whether they may cooperate or not. In our study, we consider the regenerative relays in which the decisions to cooperate are based on a signal-to-noise ratio (SNR) threshold and consider the impact of the possible erroneously detected and transmitted data at the relays. We derive the end-to-end bit-error rate (BER) expression and its approximation for binary phase-shift keying modulation and look at two power allocation strategies between the source and the relays in order to minimize the end-to-end BER at the destination for high SNR. Some selected performance results show that computer simulations based results coincide well with our analytical results.
Differential distributed space-time coding (D-DSTC) is a cooperative transmission technique that can improve diversity in wireless relay networks in the absence of channel information. Conventionally, it is assumed th...
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Differential distributed space-time coding (D-DSTC) is a cooperative transmission technique that can improve diversity in wireless relay networks in the absence of channel information. Conventionally, it is assumed that channels are flat-fading and relays are perfectly synchronized at the symbol level. However, due to the delay spread in broadband systems and the distributed nature of relay networks, these assumptions may be violated. Hence, inter-symbol interference (ISI) may appear. This paper proposes a new differential encoding and decoding process for D-DSTC systems with multiple relays over slow frequency-selective fading channels with imperfect synchronization. The proposed method overcomes the ISI caused by frequency-selectivity and is robust against synchronization errors while not requiring any channel information at the relays and destination. Moreover, the maximum possible diversity with a decoding complexity similar to that of the conventional D-DSTC is attained. Simulation results are provided to show the performance of the proposed method in various scenarios.
This work proposes adaptive buffer-aided distributed space-time coding schemes and algorithms with feedback for wireless networks equipped with buffer-aided relays. The proposed schemes employ a maximum likelihood rec...
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This work proposes adaptive buffer-aided distributed space-time coding schemes and algorithms with feedback for wireless networks equipped with buffer-aided relays. The proposed schemes employ a maximum likelihood receiver at the destination, and adjustable codes subject to a power constraint with an amplify-and-forward cooperative strategy at the relays. The adjustable codes are part of the proposed space-timecoding schemes and the codes are sent back to relays after being updated at the destination via feedback channels. Each relay is equipped with a buffer and is capable of storing blocks of received symbols and forwarding the data to the destination if selected. Different antenna configurations and wireless channels, such as static block fading channels, are considered. The effects of using buffer-aided relays to improve the bit error rate (BER) performance are also studied. Adjustable relay selection and optimization algorithms that exploit the extra degrees of freedom of relays equipped with buffers are developed to improve the BER performance. We also analyze the pairwise error probability and diversity of the system when using the proposed schemes and algorithms in a cooperative network. Simulation results show that the proposed schemes and algorithms obtain performance gains over previously reported techniques.
Differential distributed space-time coding (D-DSTC) has been considered to improve both diversity and data-rate in cooperative communications in the absence of channel information. However, conventionally, it is assum...
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ISBN:
(纸本)9781479935123
Differential distributed space-time coding (D-DSTC) has been considered to improve both diversity and data-rate in cooperative communications in the absence of channel information. However, conventionally, it is assumed that relays are perfectly synchronized in the symbol level. In practice, this assumption is easily violated due to the distributed nature of the relay networks. This paper proposes a new differential encoding and decoding process for D-DSTC systems with two relays. The proposed method is robust against synchronization errors and does not require any channel information at the destination. Moreover, the maximum possible diversity and symbol-by-symbol decoding are attained. Simulation results are provided to show the performance of the proposed method for various synchronization errors and the fact that our algorithm is not sensitive to synchronization error.
A signal detection technique using successive interference cancellation (SIC) for uplink cooperative cellular systems is proposed in this paper, to suppress the interference caused by the cooperative transmission of t...
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ISBN:
(纸本)9781424462520
A signal detection technique using successive interference cancellation (SIC) for uplink cooperative cellular systems is proposed in this paper, to suppress the interference caused by the cooperative transmission of two mobile users transmitting both their own information and the cooperative partner's information using distributed space-time coding (DSTC). Simulation results show that the proposed scheme outperforms the existing joint DSTC and equalization scheme in terms of system performance with time division multiple access.
space-timecoding can effectively increase the communication capacity in multiple antenna systems. In case the terminals cannot be equipped with antenna arrays, distributed space-time coding (DSTC) can be applied to v...
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ISBN:
(纸本)9781457701016
space-timecoding can effectively increase the communication capacity in multiple antenna systems. In case the terminals cannot be equipped with antenna arrays, distributed space-time coding (DSTC) can be applied to virtual MIMO channel which is constructed by several single-antenna terminals. A novel way of searching relays for DSTC based on decentralized ad hoc networks is proposed in this paper. The major merit of the new scheme is that the scope of selecting the cooperative relay node is far beyond the SISO transmission range. Thus more opportunities for cooperation are provided, even when the network density is low or the traffic is heavy. As a result, the transmission range is greatly extended without reducing the QoS. Besides, corresponding MAC and routing protocols are presented. Simulation results show that as compared with using SISO, end-to-end throughput of the network increases by 103.9%, while end-to-end latency is reduced by 87.6%.
Differential distributed space-time coding ( DDSTC) has been proved to be suitable for wireless relay networks, since it can provide spatial diversity without the need for channel state information at neither the tran...
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ISBN:
(纸本)9781479989669
Differential distributed space-time coding ( DDSTC) has been proved to be suitable for wireless relay networks, since it can provide spatial diversity without the need for channel state information at neither the transmitter nor the receiver side. However, DDSTC suffers from significant error floor in fast-fading channel conditions with high Doppler frequencies due to rapid time variations. For this reason, multiple-symbol differential detection ( MSDD) has been proposed in the past, where the detection process involves a larger window size of the received symbols. So far, differential detection for vehicle-to-vehicle ( V2V) networks has been studied only for single Rayleigh channels. However, experimental and theoretical studies report that double Rayleigh can be considered as an appropriate fading channel model for V2V networks. In this paper, we assess the error performance of a DDSTC scheme operating in a V2V network using MSDD. Simulation results confirm that the error performance of such a system can be improved significantly with MSDD under different channel time-variation scenarios.
In this paper, we analyze the diversity-multiplexing tradeoff (DMT) performance of opportunistic relaying coded cooperation (ORCC) and distributed space-time coding coded cooperation (DSTCCC) with arbitrary number of ...
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In this paper, we analyze the diversity-multiplexing tradeoff (DMT) performance of opportunistic relaying coded cooperation (ORCC) and distributed space-time coding coded cooperation (DSTCCC) with arbitrary number of relays. Exact DMT curves are derived for two scenarios, i.e., when the source is included in cooperation (denoted by S1) or not (denoted by S2), by formulating the problem as linear optimization problem. The DMT curves of ORCC and DSTCCC are found to be identical for S1 (or S2), and S1 has better DMT performance than S2. Numerical results are provided to illustrate the analysis as well.
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