In this paper, spatial channel pairing(SCP) is introduced to coherent combining at the relay in relay networks. Closed-form solution to optimal coherent combining is derived. Given coherent combining, the approximate ...
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In this paper, spatial channel pairing(SCP) is introduced to coherent combining at the relay in relay networks. Closed-form solution to optimal coherent combining is derived. Given coherent combining, the approximate SCP solution is presented. Finally, an alternating iterative structure is developed. Simulation results and analysis show that, given the symbol error rate and data rate, the proposed alternating iterative structure achieves signal-to-noise ratio gains over existing schemes in maximum ratio combining(MRC) plus matched filter,MRC plus antenna selection, and distributed space-time block coding due to the use of SCP and iterative structure.
An improved scheme with cooperative diversity based on distributed space-time block coding (WCD- DSTBC) is proposed, which effectively achieves diversity gains and improves the performance of the system by sharing s...
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An improved scheme with cooperative diversity based on distributed space-time block coding (WCD- DSTBC) is proposed, which effectively achieves diversity gains and improves the performance of the system by sharing some single-antenna users' antennas to form a virtual antenna array and combining with distributedspacetimeblockcoding (DSTBC) mode. Then the relation between the system BER and the interuser BER for WCDDSTBC scheme is theoretically derived and the closed-form expression of BER for WCD-DSTBC system is obtained. The simulation results show that the proposed WCD-DSTBC scheme achieves distinct gains over the non-cooperative multi-carrier CDMA (MC-CDMA) system. When system BER is le-3 and interuser BER is le-3, about 2.5 dB gain can be gotten. When interuser channel state information (CSI) outgoes the users' individual CSI, about 3 dB gain is also achieved.
distributed space-time block coding (STBC) is a promising technique for future broadband wireless communication system, because of its substantially improving the reliability of wireless channel by exploiting cooperat...
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distributed space-time block coding (STBC) is a promising technique for future broadband wireless communication system, because of its substantially improving the reliability of wireless channel by exploiting cooperative spatial diversity. In this study, the authors propose a novel two time slots distributedtime-reversal STBC scheme for amplify-and-forward relay-assisted single-carrier (SC) block transmissions over frequency-selective fading channel. They first exploit the discrete Fourier transform extended properties to construct a linear precoding matrix. They then employ a low-complexity suboptimal frequency domain decision feedback equalisation (FD-DFE) to collect potential multipath diversity at high signal-to-noise ratio. Simulation results demonstrate that the proposed scheme provides better performance than the conventional distributed SC-STBC scheme with minimum-mean-square error FD linear equalisation.
Most research on distributed space-time block coding (D-STBC) has so far focused on the case of 2 relay nodes and assumed that the relay nodes are perfectly synchronised at the symbol level. This paper applies STBC to...
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Most research on distributed space-time block coding (D-STBC) has so far focused on the case of 2 relay nodes and assumed that the relay nodes are perfectly synchronised at the symbol level. This paper applies STBC to 4-relaynode systems under quasi-synchronisation and derives a new detector based on parallel interference cancellation, which proves to be very effective in suppressing the impact of imperfect synchronisation.
How to improve the reliable performance of information transmission is a fundamental issue in wireless relay network. Following maximum ratio combining(MRC) at relay station(RS), a maximum rate(Max-Rate) based spatial...
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How to improve the reliable performance of information transmission is a fundamental issue in wireless relay network. Following maximum ratio combining(MRC) at relay station(RS), a maximum rate(Max-Rate) based spatial channel pairing(SCP) is proposed to further improve the reliable performance of information transmission in relay networks and its approximate closed-form solution is derived. The combination of MRC and Max-Rate based SCP is called Max-Rate SCP plus MRC, which includes three steps:channel phase cancellation, MRC, and SCP. From our simulation and analysis, compared to existing distributed space-time block coding and coherent combining(CC) schemes without SCP, the proposed Max-Rate SCP plus MRC achieves appreciable improvements in symbol error rate for medium and high signal-to-noise ratio regimes due to the use of Max-Rate SCP.
Significant performance gain can potentially be achieved by employing distributed space-time block coding (D-STBC) in ad hoc or mesh networks. So far, however, most research on D-STBC has assumed that cooperative rela...
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Significant performance gain can potentially be achieved by employing distributed space-time block coding (D-STBC) in ad hoc or mesh networks. So far, however, most research on D-STBC has assumed that cooperative relay nodes are perfectly synchronized. Considering the difficulty in meeting such an assumption in many practical systems, this paper proposes a simple and near-optimum detection scheme for the case of two relay nodes, which proves to be able to handle far greater timing misalignment than the conventional STBC detector.
Mobile users with single antennas can still take advantage of spatial diversity through cooperative space-time-encoded transmission. In this paper, we considered a scheme in which a relay chooses to cooperate only if ...
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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 considered 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 targeted end-to-end data rate R. We derived the end-to-end outage probability for a transmission rate R and a code rate and look at a power allocation strategy between the source and the relays in order to minimize the end-to-end outage probability at the destination for high signal-to-noise ratio, by using the golden section search method. Performance results show that the computer simulations-based results coincide with our analytical results. Copyright (c) 2011 John Wiley & Sons, Ltd.
Cooperative communications is a class of techniques that seek to improve reliability and throughput in wireless systems by pooling the resources of distributed nodes. Although cooperation can occur at different networ...
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Cooperative communications is a class of techniques that seek to improve reliability and throughput in wireless systems by pooling the resources of distributed nodes. Although cooperation can occur at different network layers and time scales, physical-layer cooperation at symbol time scales offers the largest benefit in combating losses due to fading. However, symbol-level cooperation poses significant implementation challenges, particularly in synchronizing the behavior and carrier frequency of distributed nodes. We present the implementation and characterization of a complete real-time cooperative physical-layer transceiver built on the Rice University Wireless Open-Access Research Platform (WARP). In our implementation, autonomous nodes employ physical-layer cooperation without a central synchronization source and can select between noncooperative and cooperative communications per packet. Cooperative transmissions use a distributed Alamouti space-timeblock code (STBC) and employ either amplify-and-forward (AF) or decode-and-forward (DF) relaying. We also present experimental results of our transceiver's real-time performance under various topologies and propagation conditions. Our results clearly demonstrate significant performance gains (more than 40x improvement in packet error rate in some topologies) provided by physical-layer cooperation, even when subject to the constraints of a real-time implementation. Finally, we present methodologies for isolating and understanding the sources of performance bottlenecks in our design. As with all our work on WARP, our transceiver design and experimental framework are available through the open-source WARP repository for use by other wireless researchers.
This paper presents a simple single-carrier (SC) distributedspace-timeblock coded transmission scheme for asynchronous cooperative communications over frequency-selective channels. The cyclic prefix (CP) at the sour...
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ISBN:
(纸本)9788955191356
This paper presents a simple single-carrier (SC) distributedspace-timeblock coded transmission scheme for asynchronous cooperative communications over frequency-selective channels. The cyclic prefix (CP) at the source node and relay nodes is used to combat inter-symbol interference from multi-path fading and the timing errors from the relay nodes. In this scheme, the relay nodes only implement very simple operations on their received signals to construct distributedspace-timeblock code, and decoding, DFT and IDFT operations are only needed at the destination node. The low complexity SC zero-forcing frequency domain equalization (ZF-FDE) is applied at the destination node to recover the transmitted signals. The analysis and simulation results demonstrate that this simple SC scheme can achieve order-two spatial diversity gain for amplify-and-forward based cooperative communication over frequency-selective channels in the presence of asynchronization between relay nodes.
Quasi-orthogonal space-timeblock codes (QO-STBCs) are a powerful code family designed for more than two transmit antennas. In contrast to their orthogonal counterparts designed for the same number of transmit antenna...
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Quasi-orthogonal space-timeblock codes (QO-STBCs) are a powerful code family designed for more than two transmit antennas. In contrast to their orthogonal counterparts designed for the same number of transmit antennas, QO-STBCs are able to provide full-rate transmission rate. While original QO-STBCs enjoy only a partial diversity, the recently proposed rotated versions of QO-STBCs achieve the maximum diversity order which is equal to the number of transmit antennas. Since QO-STBCs have been originally proposed foe frequency-flat fading channels, it is a challenging design problem to apply them over frequency-selective channels. The dispersive nature of such channels results in intersymbol interference which needs to be carefully handled at the receiver. In this paper, we investigate time-domain equalization for QO-STBC, exploiting the embedded quasi-orthogonal structure to design low-complexity receivers. We also present diversity gains for the proposed scheme through pairwise error probability (PEP) derivation and analysis which are further confirmed by. Monte Carlo simulations.
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