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ABSTRACT: Orthogonal space-time block codes (OSTBCs) have attracted considerable attention due to their low complexity linear decoding
and full diversity in Rayleigh fading channels. However, OSTBCs exist only for certain numbers of transmit antennas and do
not provide full code rate when more than two transmit antennas are used. In this paper, a novel rate-2 algebraic space-time
code that combines coordinate-interleaving and group precoding is proposed. By properly choosing the designed parameters,
the coding scheme can achieve full diversity order and high coding gain. The receiver adopts polynomial complexity sphere
decoding algorithm to get maximum likelihood (ML) performance. Analysis and simulations illustrate that the new code exhibits
significant performance gain over the conventional OSTBCs and diagonal algebraic space-time code.
Frontiers of Electrical and Electronic Engineering in China 04/2012; 4(4):371-377.
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ABSTRACT: A two-path amplify-and-forward (AF) relaying scheme, which uses two relays to retransmit for the source alternately, was proposed
by Rankov [Rankov et al. IEEE Journal on Selected Areas in Communications, 2007, 25 (2): 379–389]. This scheme can avoid half-duplex
loss in spectral efficiency, but it cannot work well when the interrelay channel gain is strong. An efficient detection scheme
for two-path AF relaying system is proposed in this paper. In the proposed scheme, interference cancellation is first performed
at the destination so that the received signal after interference cancellation is the superposition of two symbols with noise.
Then, a low complexity soft maximum a posteriori (MAP) decoder and an iterative soft decoder are employed to extract the diversity
of the two relay-destination links. The proposed detection scheme can efficiently improve the system performance compared
to the detection scheme presented by Rankov (2007), especially when the inter-relay channel gain is strong.
Frontiers of Electrical and Electronic Engineering in China 04/2012; 5(1):29-35.
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ABSTRACT: A family of space-time block codes (STBCs) for systems with even transmit antennas and any number of receive antennas is proposed.
The new codeword matrix is constructed by concatenating Alamouti space-time codes to form a block diagonal matrix, and its
dimension is equal to the number of transmit antennas. All Alamouti codes in the same codeword matrix have the same information;
thus, full transmit diversity can be achieved over fading channels. To improve the spectral efficiency, multi-level modulations
such as multi-quadrature amplitude modulation (M-QAM) are employed. The symbol mapping diversity is then exploited between
transmissions of the same information from different antennas to improve the bit error rate (BER) performance. The proposed
codes outperform the diagonal algebraic space-time (DAST) codes presented by Damen [Damen et al. IEEE Transactions on Information
Theory, 2002, 48(3): 628–636] when they have the same spectral efficiency. Also, they outperform the 1/2-rate codes from complex
orthogonal design. Moreover, compared to DAST codes, the proposed codes have a low decoding complexity because we only need
to perform linear processing to achieve single-symbol maximum-likelihood (ML) decoding.
Keywordsspace-time block codes (STBCs)-symbol mapping-spectral efficiency-decoding complexity-pair-wise error probability (PEP)
Frontiers of Electrical and Electronic Engineering in China 04/2012; 5(4):464-469.
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Int. J. Communication Systems. 01/2011; 24:295-309.
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Wireless Sensor Network. 01/2009; 1:1-6.
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Science in China Series F: Information Sciences. 01/2009; 52:2296-2307.
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Science in China Series F: Information Sciences. 01/2009; 52:1418-1427.
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ABSTRACT: A bandwidth efficient three-user cooperative diversity scheme based on relaying superposition symbols is proposed. Each user has two partners and each partner relays superposition symbols of the other two users instead of repetition. Thus, the bandwidth efficiency is improved compared to the baseline decode-and-forward cooperative diversity scheme in which each user retransmits its partner¿s information by employing repetition coding. The proposed scheme can also offer diversity order of two. Then, a new constellation labeling for the superposition 8PSK modulation to exploit the symbol mapping diversity is designed and it is a simple way to obtain a gain of about 2 dB.
Communication Systems, 2008. ICCS 2008. 11th IEEE Singapore International Conference on; 12/2008
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ABSTRACT: A bandwidth efficient three-user cooperative diversity scheme is proposed. Each user has two partners who receive its symbols and rotate the phases of these symbols. Then, two partners retransmit the real parts and imaginary parts of these rotated symbols, respectively. This scheme can offer diversity order of three, and the bandwidth efficiency is only decreased by 1/2 compared to a noncooperative diversity scheme. The optimal rotation angles are derived when QPSK and 8PSK modulations are employed, respectively. Then, a new symbol mapping for 8PSK modulation is proposed, and it is a simple way to improve the system performance.
IEEE Signal Processing Letters 02/2008; · 1.39 Impact Factor
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ABSTRACT: In this letter, we propose a hybrid analog/digital detection algorithm, the Correlated Interference Cancellation (CIC) algorithm,
for Impulse Radio Ultra-WideBand (IR-UWB) system. The CIC algorithm correlates received signal with its delayed versions in
the analog domain and samples the correlation output at the symbol rate. The symbol rate samples are processed in the digital
domain to perform interference cancellation. Therefore, CIC works for high data rate systems with heavy InterSymbol Interference
(ISI). Simulation results show that CIC achieves good performance in typical UWB channels.
Journal of Electronics (China) 01/2008; 25(5):685-688.
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ABSTRACT: This paper analyzes and compares performances of several improved medium access control (MAC) protocols and CSMA/CA protocol when the data rate is high (at least 1 Gbps), then proposes a novel MAC protocol, called pseudo-time division backoff scheme (PTDBS). The proposed scheme can be implemented in IEEE 802.15.3c easily and it can become an improved access control method in contention access period (CAP) for existing IEEE 802.15.3 MAC. PTDBS has been validated using OPNET network simulator. The results show that PTDBS offers higher throughput, lower delay and completion rate of close to one when the traffic load is heavy compared with the CSMA/CA protocol and other improved MAC protocols.
Intelligent Signal Processing and Communication Systems, 2007. ISPACS 2007. International Symposium on; 01/2008
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ABSTRACT: The limited bandwidth and the finite battery power of mobile devices represent one of the greatest limitations of current WPANs. In this paper, an analytical model for the energy efficiency of the IEEE 802.15.4 slotted CSMA/CA which can be studied as slotted non-persistent CSMA was proposed and validated. Key to the accuracy of the model is a careful study of the idle period after last collision, which has been studied by Zhang et al. (2006). Specifically, a distributed mechanism to improve the energy efficiency for contention control in IEEE 802.15.4 was also present and evaluated and show that power saving and throughput maximization can be jointly achieved. Simulation results indicate that our mechanism is very effective and robust. This mechanism can be used to extend the standard 802.15.4 access mechanism without requiring any additional hardware.
Wireless Communications and Networking Conference, 2007.WCNC 2007. IEEE; 04/2007
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ABSTRACT: In this paper, the multiband complex wavelet used as multi-carrier basis function is optimized. On the basis of analyzing
the principle of multi-carrier code division multiple access (MC-CDMA), a new multiband complex wavelet based MC-CDMA (MBCW-MC-CDMA)
system model is proposed, and space diversity combining (SDC) technique is employed to improve the system performance further.
The uplink performance of proposed MBCW-MC-CDMA system with SDC technique is investigated in Rayleigh fading channel, and
corresponding bit error rate (BER) analysis is given in detail. Without any cyclic prefix (CP), the system can avoid the decrease
of spectrum efficiency and data rate of conventional MC-CDMA with CP. By comparison, our scheme outperforms real wavelet packet
based MC-CDMA and slightly outperforms conventional MC-CDMA with CP via utilizing superior properties of the optimized multiband
complex wavelet. Theoretical analysis and simulation result show that the application of SDC technique can improve the proposed
system ability to combat spatial fading and various interferences effectively. Moreover, the proposed system based on SDC
technique has superior BER performance over conventional DFT and SDC based MC-CDMA system and real wavelet packet and SDC
based MC-CDMA system.
Wireless Personal Communications 03/2007; 41(2):193-206. · 0.46 Impact Factor
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ABSTRACT: Space-time block (STB) coding has been an effective transmit diversity technique for combating fading recently. In this paper, a full-rate and low-complexity STB coding scheme with complex orthogonal design for multiple antennas is proposed, and turbo code is employed as channel coding to improve the proposed code scheme performance further. Compared with full-diversity multiple antennas STB coding schemes, the proposed scheme can implement full data rate, partial diversity and a smaller complexity, and has more spatial redundancy information. Moreover, using the proposed scheme can form efficient spatial interleaving, thus performance loss due to partial diversity is effectively compensated by the concatenation of turbo coding. Simulation results show that on the condition of the same system throughput and concatenation of turbo code, the proposed scheme has lower bit error rate (BER) than those low-rate and full-diversity multiple antennas STB coding schemes.
International Journal of Information Technology & Decision Making (IJITDM). 01/2007; 06(01):5-14.
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ABSTRACT: In this paper, full-rate and complex orthogonal space-time block code (STBC) schemes for multiple antennas are proposed, and turbo code is employed as channel coding to improve the proposed STBC schemes performance further. Compared with full-diversity multiple antennas STBC schemes, the proposed schemes can implement full data rate, partial diversity and a smaller complexity. On the condition of the same system throughput and concatenation of turbo code, the proposed schemes have lower bit error rate (BER) than those low-rate and full-diversity code schemes.
Wireless Personal Communications 12/2006; 40(1):81-89. · 0.46 Impact Factor
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ABSTRACT: In this paper, we propose and validate an analytical model for the saturation throughput of the IEEE 802.15.4 slotted CSMA/CA which can be studied as slotted non-persistent CSMA. Key to the accuracy of our model is a careful study of the idle period after last collision, which has not been considered by all previous 802.15.4 models. Specifically, we also derive the probability of sensing the channel that maximizes the throughput and provide analytical closed formulas. With results from the OPNET simulator, we show that our model can accurately predict the saturation throughput over a wide range of scenarios
Communication systems, 2006. ICCS 2006. 10th IEEE Singapore International Conference on; 11/2006
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ABSTRACT: Recently, noncoherent UWB radios have generated increasing interest among researchers due to the advantage of not requiring channel state information (CSI) at both transmitter and receiver. However, the trade-off is a penalty of approximately 3 dB in the required SNR compare to the coherent case. In order to overcome the gap, in this paper, we propose a differential encoding and decoding scheme for multiband UWB systems. The proposed scheme employs the parallel concatenation of two differential unitary space-frequency encoders at the transmitter and performs a simple soft decision iterative decoding at the receiver. Simulation results show that the proposed scheme can outperform the conventional differential and coherent detection at high SNR with few number of iterations.
Information Theory Workshop, 2006. ITW '06 Punta del Este. IEEE; 11/2006
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ABSTRACT: By introducing full-rate space-time block coding (STBC) scheme, a full-rate space-time block coded CDMA (FSTBC-CDMA) system for downlink in time division duplex mode is given. Considering that existing space-time coded CDMA system has high decoding complexity, a low-complexity multiuser receiver scheme is also proposed. The scheme can make full use of the complex orthogonality of STBC to simply the high decoding complexity of the existing scheme after multiuser detection method is employed to suppress multiuser interference effectively; it has linear decoding complexity when compared with the existing scheme. Moreover, compared with full-diversity space-time block coded CDMA, our given FSTBC-CDMA system can implement full rate, low complexity and partial diversity, has more spatial redundant information. Thus the concatenation of channel coding can effectively make up for the performance loss due to partial diversity. Simulation results show that the proposed FSTBC-CDMA system has lower bit error rate (BER) than those low-rate and full-diversity space-time block coded CDMA system on the condition of same system throughput and concatenation of channel code
Communications, Circuits and Systems Proceedings, 2006 International Conference on; 07/2006
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ABSTRACT: In this paper, a Complex Wavelet Packet based Multi-Carrier Code Division Multiple Access (CWP-MC-CDMA) system uplink model
is proposed, based on the analysis of the principle of MC-CDMA and the use of the optimized complex wavelet packet. Considering
that the base station can adopt multiple receiver antennas in the uplink, we employ the Space Diversity Combining (SDC) technique
to improve the system performance via multiple antennas. The uplink performance of proposed CWP-MC-CDMA system with SDC technique
is investigated over Rayleigh fading channel, and corresponding bit error rate analysis is given in detail. The system can
avoid the decrease of spectrum efficiency of conventional MC-CDMA due to inserting cyclic prefix. Theoretical analysis and
simulation result show that the application of SDC technique can improve the CWP-MC-CDMA system ability to combat spatial
fading and various interferences effectively. Moreover, the proposed system based on SDC technique has superior Bit Error
Rate (BER) performance over the Discrete Fourier Transform (DFT) and SDC based MC-CDMA system and the real wavelet packet
and SDC based MC-CDMA system.
Journal of Electronics (China) 01/2006; 23(6):837-841.
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ABSTRACT: This paper gives a brief survey on UWB technology, including its definitions, regulations, and representative schemes. UWB research and development status in China is also introduced.
Microwave Conference Proceedings, 2005. APMC 2005. Asia-Pacific Conference Proceedings; 01/2006
