Guo Wei

University of Science and Technology of China, Luchow, Anhui Sheng, China

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Publications (96)25.66 Total impact

  • Xu Li, Huarui Yin, Ying Xu, Guo Wei
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    ABSTRACT: In cellular networks, global channel state information (CSI) shall be shared among neighboring cells to mitigate various inter-cell interference (ICI). In this paper, we propose that comparable ICI is mitigated while weak ICI is treated as noise. The amount of shared CSI is highly reduced, because of that only the CSI corresponding to comparable ICI is shared among neighboring cells. In the case of single user equipment in each cell, a joint singular value decomposition and interference alignment method is proposed along with the analysis of its approximate sum rate. Some nodes select singular value decomposition method, while others choose interference alignment method. The method at each node is determined by global selection principle or user classification principle. In the case of multiple UEs in each cell, all nodes utilize minimum mean square error method, but ICI is neglected at cell center users. Copyright © 2014 John Wiley & Sons, Ltd.
    International Journal of Communication Systems 10/2014; DOI:10.1002/dac.2880 · 1.11 Impact Factor
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    ABSTRACT: Deploying relays and/or mobile base stations is a major means of extending the coverage of a wireless network. This paper presents models, analytical results, and algorithms to answer two related questions: The first is where to deploy relays in order to extend the reach from a base station to the maximum; the second is where to deploy a mobile base station and how many relays are needed to reach any point in a given area. Simple time-division and frequency-division scheduling schemes as well as an end-to-end data rate requirement are assumed. An important use case of the results is in the Public Safety Broadband Network, in which deploying relays and mobile base stations is often crucial to provide coverage to an incident scene.
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    ABSTRACT: Future communication system requires large bandwidths to achieve high data rates, thus rendering analog-to-digital conversion (ADC) a bottleneck due to its high power consumption. In this paper, we consider monobit receivers for QPSK. The optimal monobit receiver under Nyquist sampling is obtained and its performance is analyzed. Then, a suboptimal but low-complexity receiver is proposed. The effect of imbalances between In-phase (I) and Quadrature (Q) branches is carefully examined. To combat the performance loss due to IQ imbalances, monobit receivers based on double training sequences and eight-sector phase quantization are proposed. Numerical simulations show that the low-complexity suboptimal receiver suffers 3dB signal-to-noise-ratio (SNR) loss in additive white Gaussian noise (AWGN) channels and only 1dB SNR loss in multipath channels compared with matched-filter monobit receiver with perfect channel state information (CSI). It is further demonstrated that the amplitude imbalance has essentially no effect on monobit receivers. In AWGN channels, receivers based on double training sequences can efficiently compensate for the SNR loss without complexity increase, while receivers with eight-sector phase quantization can almost completely eliminate the SNR loss caused by IQ imbalances. In dense multipath channels, the effect of imbalances on monobit receivers is slight.
    IEEE Transactions on Communications 08/2013; 61(8):3292-3303. DOI:10.1109/TCOMM.2013.061913.120304 · 1.98 Impact Factor
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    ABSTRACT: This paper studies fairness problem concerning admission control and beamforming design in the multiple-input-and-single-output (MISO) downlink channel with various users: guaranteed users (GUs) who have the requirements on individual signal-to-interface-noise ratios (SINR) and best-effort users (BUs) who have no such requirements. The problem is modeled as maximizing the worst SINR of BUs while meeting SINR requirements of GUs and limiting total power of base station (BS). We figure out feasibility of the problem with solving the max-min-weighted-fairness (MMWF) problem. If it is feasible, we propose a heuristic removal algorithm to turn the infeasible problem into a feasible one; otherwise, we study the relation between the feasible problem and the MMWF problem by introducing auxiliary variables. Based on that relation, a fixed-point iterative algorithm converging to the optimal solution is proposed to solve the feasible problem. Besides, the algorithm can be implemented distributively. Simulation results reveal the effectiveness of the heuristic removal algorithm, and the optimality and fast convergence of the fixed-point iterative algorithm.
    Communications in China - Workshops (CIC/ICCC), 2013 IEEE/CIC International Conference on; 01/2013
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    ABSTRACT: High-speed high-resolution analog-to-digital converter (ADC) is a key bottleneck in large-bandwidth systems such as 60 GHz communication of wireless personal area networks (WPANs), due to its large power consumption and high complexity. Hence, monobit ADC has been previously proposed to address this problem. In this paper, we propose a receiver architecture with monobit sampling and carrier phase rotation for quadrature-phase-shift-keying (QPSK) modulation. The optimal rotation phase is derived from the achievable-rate point of view. Then, a suboptimal but low-complexity monobit receiver is obtained, and the impact of different rotation phases is investigated. The optimal rotation phase is found to be π/4. Simulation results show that there is only about 1dB signal-to-noise ratio (SNR) loss with a rotation phase deviation of 15° from the optimal value, providing a pretty good robustness to implementation imperfection.
    Communications in China (ICCC), 2013 IEEE/CIC International Conference on; 01/2013
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    ABSTRACT: The problem of joint user selection and multicast beamforming design in the downlink cochannel is studied in our paper. The primary goal is to maximize the number of served users, and minimizing the transmitting power is the second one. We reformulate the problem into a form suitable for analyzing by introducing two-value auxiliary variables, then relax it into a general problem. Different approximations are discussed to turn the general problem into easy-handling problems, which covering several works in both unicast and multicast scenes. An algorithm is proposed based on analyzing two characteristics in the multicast problem, inactive signal-to-interface-noise (SINR) constraints and non-rank-one beamforming covariance matrices. In simulations, three approximate functions are chosen, and their influence on the algorithm in performance and complexity is compared. Then our algorithm and MDR algorithm in [1] is contrasted and the relation between performance gap of two algorithms and characteristics in the multicast problem is discussed at last.
    Wireless Communications & Signal Processing (WCSP), 2013 International Conference on; 01/2013
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    ABSTRACT: For cellular networks, the users' location and transmit power greatly influence the strength of interference caused to neighbor cells. In this paper, we theoretically analyze the approximate sum rate performance of singular value decomposition and interference alignment transmission strategies. Based on the analysis, a novel combined transmission strategy using strategies selection is presented to improve the system performance. And this novel combined transmission strategy could highly reduce the system complexity and the demand of instant channel state information.
    Wireless Communications & Signal Processing (WCSP), 2013 International Conference on; 01/2013
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    ABSTRACT: Future communication system requires large bandwidths to achieve high data rates, rendering high-resolution analog-to-digital converter (ADC) a key bottleneck due to its high complexity and large power consumption. In this paper, we consider monobit digital receivers for QPSK modulation. First, the optimal monobit receiver under Nyquist sampling is derived. Its performance is calculated in the form of deflection ratio. Then a suboptimal but low-complexity monobit receiver is obtained. The impact of the phase offset is investigated, and the interface with error-control decoder is given. Numerical simulations show that the low-complexity suboptimal receiver suffers 3dB signal to noise ratio (SNR) loss in AWGN channels and only 1dB SNR loss in multipath channels compared with the matched-filter based monobit receiver with full channel state information (CSI).
    Vehicular Technology Conference (VTC Fall), 2013 IEEE 78th; 01/2013
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    ABSTRACT: An efficient cooperative Automatic Repeat reQuest (ARQ) protocol for distributed space–time coded cooperative networks is proposed in this paper. Conventional cooperative ARQ protocol just utilizes the relays which can decode the packet from the source in direct transmission. However, relays which can not receive the packet successfully have the ability to listen to the retransmission and decode the packet with high probability. Therefore, we consider to let these relays join in the next possible retransmission. We prove that the proposed cooperative ARQ protocol has a lower packet loss rate and average retransmission number than conventional ARQ protocol. Finally, the simulation results verify our theoretical results and show that the proposed ARQ protocol is suitable for the relay networks where the source node is close to the relay nodes.
    Computer Communications 12/2012; 36(1):105–112. DOI:10.1016/j.comcom.2012.08.002 · 1.35 Impact Factor
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    ABSTRACT: Interference alignment (IA) is a technique recently shown to achieve the maximum degrees of freedom (DoF) of $K$-user interference channel. In this paper, we focus on the precoder designs on manifolds for IA. By restricting the optimization only at the transmitters' side, it will alleviate the overhead induced by alternation between the forward and reverse links significantly. Firstly a classical steepest descent (SD) algorithm in multi-dimensional complex space is proposed to achieve feasible IA. Then we reform the optimization problem on Stiefel manifold, and propose a novel SD algorithm based on this manifold with lower dimensions. Moreover, aiming at further reducing the complexity, Grassmann manifold is introduced to derive corresponding algorithm for reaching the perfect IA. Numerical simulations show that the proposed algorithms on manifolds have better convergence performance and higher system capacity than previous methods, also achieve the maximum DoF.
    Vehicular Technology Conference, 1988, IEEE 38th 09/2012; DOI:10.1109/VTCFall.2012.6398883
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    ABSTRACT: The problem of transmit beamforming design for multicast wireless system is considered in this paper. We focus on the robust long-term transmit beamforming design with only imperfect knowledge of the channel covariance from two view points: minimizing total transmission power with prescribed signal-to-noise ratio (SNR) constraints at the receivers and maximizing the minimum SNR to achieve the relative max-min fairness. Only infrequent feedback is required from the users in such an algorithm. Furthermore, the algorithm shows great tolerance of imperfect channel state information (CSI) on both transceiver sides. It is shown that we can formulate both of the optimizations as convex semidefinite programming (SDP) problems by applying semidefinite relaxation (SDR) techniques. Extensive simulation results are presented to corroborate the performance of our proposed design.
    2012 1st IEEE International Conference on Communications in China (ICCC); 08/2012
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    ABSTRACT: Future communication system requires large bandwidth to achieve high data rate up to multigigabit/ sec, which makes analog-to-digital (ADC) become a key bottleneck for the implementation of digital receivers due to its high complexity and large power consumption. Therefore, monobit receivers for BPSK have been proposed to address this problem. In this work, QPSK modulation is considered for higher data rate. First, the optimal receiver based on monobit ADC with Nyquist sampling is derived, and its corresponding performance in the form of deflection ratio is calculated. Then a suboptimal but more practical monobit receiver is obtained, along with iterative demodulation and small sample removal. The effect of the imbalances between the In-phase (I) and Quadrature-phase (Q) branches, including the amplitude and phase imbalances, is carefully investigated too. To combat the performance loss caused by IQ imbalances, monobit receivers based on double training sequences are proposed. Numerical simulations show that the low-complexity suboptimal receiver suffers only 3dB signal to noise ratio (SNR) loss in AWGN channels and 1dB SNR loss in multipath static channels compared with the matched filter based monobit receiver with full channel state information (CSI). The impact of the phase difference between the transmitter and receiver is presented. It is observed that the performance degradation caused by the amplitude imbalance is negligible. Receivers based on double training sequences can efficiently compensate the performance loss in AWGN channel. Thanks to the diversity offered by the multipath, the effect of imbalances on monobit receivers in fading channels is slight. I
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    ABSTRACT: IEEE-802.11-based WLAN MAC performance evaluation is of great importance, especially under non-saturated conditions. A new load equation, respect to the non-saturation, is proposed for analysis of the MAC mechanism in this paper. The load equation together with a backoff equation and a transmission equation are sufficient to analyze the MAC performance under non-saturated conditions. In the new load equation, both traffic arrival and first order buffer memory are considered. In addition, a lower bound derived from the new load equation is found if traffic arrival obeys Poisson distribution. From NS2 simulation results, it is shown that the load equation using the bound outperforms the one only considering traffic arrival significantly, especially as the offered traffic load at each station is moderate.
    Communications in China (ICCC), 2012 1st IEEE International Conference on; 01/2012
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    ABSTRACT: This paper addresses a robust downlink beamforming optimization problem for the multigroup multicast scenario, when only imperfect channel state information (CSI) is available at the transmitter. We consider two different optimization criteria: minimizing the total transmit power subject to quality of service (QoS) constraints at each receiver; max-min fair (MMF) signal-to-interference- plus-noise ratio (SINR) subject to total power constraint. With the aid of S-lemma, the infinite non-convex QoS constraints of robust downlink beamforming problem are transformed into finite linear matrix inequalities (LMI). By applying the semidefinite relaxation (SDR) method, the robust downlink beamforming problem can be relaxed and solved efficiently. Simulation results are presented to corroborate our design.
    Vehicular Technology Conference (VTC Fall), 2012 IEEE; 01/2012
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    ABSTRACT: Gossiping or rumor spreading is an effective way of information dissemination, and gossiping-based schemes are promising solutions for many of the next generation networks. Despite the abundant existing works on (high-probability) completion time of gossiping processes, it remains an interesting, important, and largely unaddressed problem how to select the initial information sources for gossiping, so as to maximize the expected spreading or minimize the expected completion time. In this paper, we deal with problems related to selecting influential information sources, which are initially informed nodes in a network for gossiping. The considered problems include the gossip spreading maximization problem (GSMP) and the completion time minimization problem (CTMP). Both problems are conjectured to be at least NP-hard, whereas a greedy algorithm for GSMP is proposed to guarantee an approximation factor of (1-1/e), due to the inherent submodularity property of GSMP. Additionally, based on an all-ordered-pair matrix, three heuristics are proposed for solving CTMP. Throughout the analysis and development, a key observation is that there exists an equivalent view that relates the expected gossiping time to the expected shortest path length in a random weighted directed graph induced by virtual coupon collectors run at each node in the network graph.
    Communication, Control, and Computing (Allerton), 2012 50th Annual Allerton Conference on; 01/2012
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    ABSTRACT: In this paper, we focus on the interference alignment precoder design for cellular system. Varying from the traditional constrained optimization method, we reformulate the optimization problem on the complex Grassmann manifold and derive a novel steepest descent algorithm to achieve perfect interference alignment. Moreover our proposed algorithm only requires the participation of transmitter. Thus it will alleviate the overhead induced by alternating between the up and down links significantly. Simulation results suggest the proposed algorithm has better convergence performance and higher system capacity comparing with previous methods.
    Communications in China (ICCC), 2012 1st IEEE International Conference on; 01/2012
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    ABSTRACT: In this paper, we propose a novel complete two-dimensional shadow fading modeling on system level characterized by both spatial auto-correlation and site-to-site cross-correlation. Numerical results confirm that the proposed algorithm based on two-dimensional filter to generate shadowing auto-correlation is more approaching theoretical results comparing with the previous method, and the empirical cross-correlation coefficient is embedded well in our proposed model. Additionally, the linear interpolation scheme of the proposed model significantly reduces the computational complexity on system level simulation.
    Personal Indoor and Mobile Radio Communications (PIMRC), 2012 IEEE 23rd International Symposium on; 01/2012
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    ABSTRACT: Energy efficiency has become significantly important in designing future green mobile communication systems. In this paper, a novel energy efficiency metric, which is per energy per area capacity, is proposed to quantify the matching degree between energy consumption of Base Stations (BSs) and the traffic load. Based on BS power consumption model and Shannon capacity formula, the deployment strategies of different base station types are discussed, and the matching degree maximization is formulated as a convex optimization problem. The optimal cell size is proved to be the solution, which can be obtained by our presented iterative algorithm. Through theoretical inference and experimental simulations, we find that macro BS outperforms micro BS when the traffic density is pretty low, while it becomes reversed if the value exceeds the boundary. Besides, the heavier traffic demand results in a smaller optimal cell size.
    Communications in China (ICCC), 2012 1st IEEE International Conference on; 01/2012
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    ABSTRACT: Deliberate clipping is a simple solution to high Peak-to-Average Power Ratio problem of OFDM signal. In Amplify-and-Forward OFDM relay networks, due to the limited resource, deliberate clipping is also suggested. However, clipping is a nonlinear process and may cause significant performance degradation. Based on Bussgang Linearization Theory, we provide a linear system model for Amplify-and-Forward OFDM relay networks. To achieve spatial diversity, we design a practical nonlinear distortion aware receiver at the destination. Considering a total relay power constraint, we propose an optimal power allocation scheme to maximize the signal-to-noise distortion ratio. Simulation results show that our optimal relay power allocation scheme can improve the system throughput and resist the non-linear distortion. It is also verified that our proposed transmission scheme outperforms other transmission schemes without considering non-linear distortion.
    01/2012; DOI:10.1109/WCNC.2012.6214395
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    ABSTRACT: Two-way relay (TWR) communication, a new cooperation paradigm that allows two terminals to share one relay node to communicate with each other in two phases, has played an increasingly valuable role in wireless networks to meet the stringent throughput requirement. In this paper, we focus on the designing of automatic repeat-request (ARQ) protocols for the two-way wireless relay systems. According to different feedback schedules, we propose three basic ARQ protocols to improve the throughput of two-way relay systems, namely, relay-only ARQ (Ro-ARQ), terminal only ARQ (To-ARQ) and relay-terminal ARQ (RT-ARQ). Through analyzing the outage throughput of these three ARQ protocols, it is verified that all three protocols can improve the system performance. In addition, simulation results reveal that the RT-ARQ protocol has the closest performance to the theoretical throughput upperbound among all given methods without severe deterioration on system complexity.
    International Journal of Distributed Sensor Networks 01/2012; 2012. DOI:10.1155/2012/980241 · 0.92 Impact Factor

Publication Stats

251 Citations
25.66 Total Impact Points

Institutions

  • 2002–2013
    • University of Science and Technology of China
      • Department of Electronic Engineering and Information Science
      Luchow, Anhui Sheng, China
  • 2009
    • University of Science and Technology Chittagong
      Chittagong Ghat, Chittagong, Bangladesh
    • University of Electronic Science and Technology of China
      Hua-yang, Sichuan, China
  • 2008
    • Michigan Technological University
      • Department of Electrical & Computer Engineering
      Houghton, Michigan, United States