Zhuwei Wang

Beijing University of Posts and Telecommunications, Peping, Beijing, China

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Publications (9)4.17 Total impact

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    ABSTRACT: This paper addresses an adaptive multi-user resource allocation for a distributed multi-carrier direct sequence-code division multiple access (MC DS-CDMA) network. The packet throughput, which turns out to be nonconvex and nondifferentiable, is considered to measure the system performance. A sub-optimal non-cooperative power control game is proposed to adaptively allocate the transmit power, available subchannels and alphabet size by minimizing the transmit power with a transmit power constraint and a packet throughput requirement. Also, the paper investigates the effect of channel estimation error on the adaptive resource allocation in a distributed MC DS-CDMA network, and shows that using the Gaussian approximation for the signal-dependent noise can lead to a nontrivial discrepancy in system performance.
    IEEE Transactions on Communications 01/2012; 60:143-152. · 1.75 Impact Factor
  • Zhuwei Wang, Qihang Peng, L.B. Milstein
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    ABSTRACT: In this paper, we consider an adaptive multi-user resource allocation for the downlink transmission of a multi-cluster tactical multicarrier DS CDMA network. The goal is to maximize the sum packet throughput, subject to transmit power constraints. Since the objective function turns out to be noncovex and nondifferentiable, we propose a simple iterative bisection algorithm. At each iteration, a closed-form expression is derived for the transmit power, subchannel, and modulation assignment, which significantly reduces the computational complexity. We also provide an optimization algorithm for the downlink transmission under the condition of imperfect channel knowledge, and investigate the effects of both channel estimation error and partial-band jamming.
    IEEE Transactions on Wireless Communications 09/2011; · 2.42 Impact Factor
  • IEEE Transactions on Wireless Communications. 01/2011; 10:2534-2542.
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    ABSTRACT: In this paper, link adaptation, which dynamically selects modulation level and coding rate according to the channel condition, and several multi-input multi-output (MIMO) transmission modes are studied. As we know, the subchannels' signal-to-noise radio (SNR) by singular value decomposition (SVD) are unequal, which requires different modulation and coding schemes (MCS) to maximize the throughput. However, uniform channel decomposition (UCD) greatly reduces the coding and modulation complexity by decomposing the MIMO channel into multiple subchannels with identical capacity. This paper analyzes the post-detection SINR of different MIMO transmission modes and presents their throughput performance with link adaptation under the constraint of required packet error rate (PER). We show that UCD mode is the first choice at high SNR considering both coding/modulation complexity and throughput performance, while at low SNR, space-time block coding (STBC) mode outperforms other MIMO transmission modes.
    Radio and Wireless Symposium, 2009. RWS '09. IEEE; 02/2009
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    ABSTRACT: In this paper, a multi-user multiple input multiple output (MIMO) system using semi-orthogonal space division multiplexing (semi-OSDM) and single-user QR-triangular detection with Alamouti code is studied. In this proposed semi-OSDM with STBC system, the transmit signals for each user are grouped into pairs and separately coded by using the standard Alamouti space-time code, while QR decomposition is used to make the signaling streams triangular so that the serial interference cancellation (SIC) can be utilized to maintain an accurate signal detection at the receiver. The bit error rate (BER) performance of the proposed semi-OSDM with STBC system outperforms the orthogonal space division multiplexing (OSDM) system as well as the semi-OSDM system, while exploiting a reduced complexity and stability when the correlation of the channel changes. Moreover, it largely reduces the complexity of the receivers.
    Proceedings of the 67th IEEE Vehicular Technology Conference, VTC Spring 2008, 11-14 May 2008, Singapore; 01/2008
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    ABSTRACT: In this paper, taking the channel estimation error (CEE) and noise into consideration, an analytical expression for envelope correlation coefficient (ECC) of the maximal ratio combining (MRC) output has been obtained in correlated Rician fading environments in the high signal-to-noise ratio (SNR) region, which provides a deep insight into the impacts of CEE, noise, frequency separation, Rician factor and channel attenuation, etc. Besides, we found that the ECC can be used to predict system performance such as average channel capacity and outage probability quantitatively in the identical statistical characteristic environment.
    Proceedings of IEEE International Conference on Communications, ICC 2008, Beijing, China, 19-23 May 2008; 01/2008
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    ABSTRACT: In this paper, we provide some exact expressions in a close form for central moment envelope correlation coefficient (ECC) and joint moment ECC of the maximal ratio combining (MRC) output in correlated Rayleigh and Rician fading environments. Besides, we deduce an analytical formula for average capacity with minor approximation. With these expressions, a simple relationship between joint moment ECC and the average capacity is presented, which means that only joint moment ECC can be used to predict system performance such as average channel capacity quantitatively. Furthermore, it has been demonstrated by Monte Carlo simulation that our analysis are matched with the numerical results excellently.
    Personal, Indoor and Mobile Radio Communications, 2007. PIMRC 2007. IEEE 18th International Symposium on; 10/2007
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    ABSTRACT: This work investigates a design of minimizing the system outage probability adaptive modulation algorithm in the downlink of the multi-user multiple-input multiple-output (MIMO) system. Based on a beamforming scheme that maximizes the signal-to-leakage ratio (SLR), this new algorithm is proposed for constant bit rate services to maximize the number of satisfied users and minimize the transmission power. Furthermore, this proposed algorithm has advantage in the system spectral efficiency.
    01/2007;
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    ABSTRACT: In this paper, with minor approximation, we provide analytical expressions in a close form for the envelope correlation coefficient (ECC) and outage probability of the maximal ratio combining (MRC) output in correlated Rayleigh and Rician fading environments. Moreover, we find a simple relationship between ECC and the outage probability, which indicates that ECC can be used to predict system performance such as outage probability quantitatively. Besides, it has been demonstrated by Monte Carlo simulation that our analysis are matched with the numerical results excellently.
    Proceedings of the 66th IEEE Vehicular Technology Conference, VTC Fall 2007, 30 September - 3 October 2007, Baltimore, MD, USA; 01/2007