楼思研 李校林 张祖凡
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60257-4
In this paper, we focus on antenna array design for mobile phone with finite volume and propose a novel antenna element structure by capacitive feeding and capacitive loading method based on the planar inverted F antenna (PIFA). State-of-the-art development on this issue is reviewed. Then, a novel capacitively fed and capacitively loaded PIFA structure is proposed and studied. The results of the experiments showed that our structure can reduce the coupling of antenna elements from 13.4 dB to 24.5 dB. Finally, a design with a bandwidth of 100 MHz centered at 2.35 GHz and envelopment correlation coefficient of 0.01 2 is provided and the diversity performance of the dual-element modified PIFA array is evaluated in both simulation and measurement. In a word, our novel design reaches broadband, miniaturization, high isolation and offers excellent diversity performance.
王璐瑜 朱琦 ZHAO su
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60258-6
This paper proposes a compressed sensing (CS) scheme to reconstruct and estimate the signals. In this scheme, the framework of CS is used to break the Nyquist sampling limit, making it possible to reconstruct and estimate signals via fewer measurements than that is required traditionally. However, the reconstruction algorithms based on CS are normally non-deterministic polynomial hard (NP-hard) in mathematics, which makes difficulties in obtaining real-time analysis-results. Therefore, a new compressed sensing scheme based on back propagation (BP) neural network is proposed under an assumption that every sub-band is the same. In this new scheme, BP neural network is added into detection process, replacing for signal reconstruction and decision-making. By doing this, heavy calculation cost in reconstruction is moved into pre-training period, which can be done before the real-time analysis, bringing about a sharp reduction in time consuming. For simplify, 1-bit quantification is taken on compressed signals. Simulations demonstrate the performance enhancement in the proposed scheme: compared with normal CS-based scheme, the proposed one presents a much shorter response time as well as a better robustness performance to noise via fewer measurements.
刘雁飞 卢光跃 孙宝玉
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60259-8
The discrete Fourier transform (DFT)-based codebook is employed in this paper to quantize channel state information so that the amount of feedback can be reduced in the multiple input multiple output (MIMO) downlink of long term evolution (LTE) system. And a novel beamforming (BF) scheme based on the proposed channel quality-to-interference (QIR) quantizing criteria is developed, which uses only the index of the optimal codebook for the beamforming at the base station (BS), and dramatically reduces the amount of feedback. The proposed BF scheme jointly considers the influences of the quality of the quantized channels and the mutual interference among the sub-channels. The extensive simulation results verify that throughput of the proposed BF scheme is better than that of the random BF with a little feedback, and that of the eigen-beamforming even under low signal noise ratio (SNR) scenario.
赵军辉 李非 ZHANG Xue-xue
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60260-4
Multi-objective parameter adjustment plays an important role in improving the performance of the cognitive radio (CR) system. Current research focus on the genetic algorithm (GA) to achieve parameter optimization in CR, while general GA always fall into premature convergence. Thereafter, this paper proposed a linear scale transformation to the fitness of individual chromosome, which can reduce the impact of extraordinary individuals exiting in the early evolution iterations, and ensure competition between individuals in the latter evolution iterations. This paper also introduces an adaptive crossover and mutation probability algorithm into parameter adjustment, which can ensure the diversity and convergence of the population. Two applications are applied in the parameter adjustment of CR, one application prefers the bit error rate and another prefers the bandwidth. Simulation results show that the improved parameter adjustment algorithm can converge to the global optimal solution fast without falling into premature convergence.
陈鹏 李楠 牛凯 贺志强 吴伟陵
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60261-6
A novel scheme to joint phase noise (PHN) correcting and channel noise variance estimating for Orthogonal Frequency Division Multiplexing (OFDM) signal was proposed. The new scheme was based on the Variational Bayes (VB) method and discrete cosine transform (DCT) approximation. Compared with the least squares (LS) based scheme, the proposed scheme could overcome the over-fitting phenomenon and thus lead to an improved performance. Computer simulations showed that the proposed VB based scheme outperforms the existing LS based scheme
崔冬暖 刘元安 黎淑兰 于翠屏
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60262-8
A new compact bandpass filter based on two meandered parallel-coupled lines of different lengths in shunt is presented, using the signal-interference technique, this filter obtains a low insertion loss and sharp rejection. A set of analytical formulas and guidelines for the design of the bandpass filter are provided in two theoretical analysis methods. According to the number of attenuation poles of the reflection coefficients in the passband, it can be summed up two types of filters. To validated this topology, two wideband bandpass filters centered at 3 GHz are built to verify the theoretical prediction, the measured frequency response of the filter agrees excellently with the predicted result.
张晓亮 纪红 李曦 DAI Li-yun
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60263-X
The problem of resource allocation in cognitive radio networks plays an important role to improve the efficiency of spectrum utilization. Most of previous works focus on the power allocation for secondary users in spectrum sharing overlay or spectrum sharing underlay, which needs to frequently handoff between the idle spectrum bands or considers the interference constraints in all spectrum bands respectively. However, how to reduce the handoff between idle spectrum bands and fully utilize the spectrum resource is still an important issue. In this paper, we propose a new spectrum sharing paradigm in cognitive radio networks, which just needs to adjust the transmit power in spectrum bands instead of frequently handoff between idle spectrum bands. And this new spectrum sharing paradigm can also fully utilize the spectrum resource, this is because that we only consider the interference power constraints in active spectrum bands rather than in all spectrum bands. Then based on this new spectrum sharing paradigm and the constraint conditions, we study the distributed power allocation for secondary users. And we formulate the optimization problem as a non-cooperative game problem. And we use the variational inequality approach to solve this game problem and get a Nash Equilibria solution. Finally simulation results are illustrated to demonstrate the performance of the proposed scheme.
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60264-1
随着无线多跳网络技术作为无线通信领域中一种新兴网络结构逐渐得到发展，越来越多的P2P系统开始尝试部署于无线多跳网络上，如无线传感网络，Ad hoc网络等。而无线网络所能提供的数据传输速率和稳定性又远远不及有线网络，这更加重了大规模P2P系统的部署难度。无线MESH网络作为新的无线网络技术，由于其所具有的高速率、易组网、成本低、性能稳定等优势，引起人们的日益关注，成为了下一代无线网络的关键技术。在无线MESH网络中部署P2P共享系统成为研究的热点之一。本文旨在解决P2P资源共享系统的主要问题——如何以有效的手段快速响应无线MESH网络中用户的资源请求。文章提出了一种特殊的CHORD算法——SpiralChord, 将位置知晓策略与基于无线广播特性的跨层策略相结合，提出基于spiral空间填充曲线的节点ID分配策略以此来缓解覆盖网络与物理网拓扑不匹配问题。位置知晓要求邻居节点具有接近的ID，而跨层策略期望邻居节点具有差异较大的ID，两者需求彼此矛盾。SpiralChord注重位置知晓与跨层间的交互作用，利用sprial曲线来进行ID分配，同时满足位置知晓与跨层的要求。实验证明sprialchord能有效的减少无线文件共享系统中的消息冗余，同时提高文件查找效率。
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60265-3
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60266-5
郭威 郑霖 仇洪冰
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60267-7
In wireless networks, the majority of cooperative communications rely on the high-accuracy timing synchronization among isolated nodes. However, most presented physical-layer distributed synchronization algorithms so far cannot satisfy the requirement for real applications. To realize frequency and phase synchronization of distributed clocks, i.e., full synchronization, inspired by the character of the proportional plus integral controller that it may help an unstable system be a no steady-state error one, a new loop structure of distributed discrete phase-locked loop (PLL) is designed. Furthermore, by using algebraic graph theory, the convergence of this scheme is analyzed for both directed and undirected networks, and full synchronization is proved to be reached. Simulation results are given to corroborate the proposed algorithm and analysis.
宋晓鸥 向新 毕笃彦 DENG Yong
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60268-9
According to the problem of cognitive UWB spectrum sensing, a novel UWB pulse signal detection algorithm based on Cumulative Sum (CUSUM) test is proposed in this paper. Based on the analysis of the existing spectrum sensing schemes for Cognitive UWB system, some obvious facts are obtained that it is difficult to detect Ultra Wide-band (UWB) pulse signal with conventional spectrum sensing schemes, due to its low average SNR, large bandwidth, and low duty ratio. In this paper the detection algorithm of signal distribution change, which is application of CUSUM test, is considered to be applied to cognitive UWB spectrum sensing. But CUSUM test request that the pre-change and the post-change distributions are i.i.d, which cannot be satisfied in the detection process of UWB pulse signal. Since there are two time domain descriptions on UWB pulse signal, namely one contains only noise and the other one contains pulse signal plus noise, the existing detection algorithm of signal distribution change cannot be directly applied to detect UWB pulse signal. Hence the uniform probability density function expression of UWB pulse signal is first deduced, then CUSUM test is applied to Cognitive UWB spectrum sensing. The proposed algorithm is a time sequential detection algorithm, with low complexity and minimal detection delay, which is suitable to detect the low duty ratio signal. Its performance is evaluated through theoretical analysis and numerical simulations. It is shown that this algorithm outperforms the conventional energy detection algorithm and conquers SNR wall phenomenon.
张龙昌 杨放春 YU Zhang-lin
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60269-0
In open and dynamic Internet environment, multi-periods QoS, multiple decision-makers based on heterogeneous QoS models and uncertainty weights make optimal Web service selection hard. To solve the above difficulties, dynamic Web service selection group decision making based on heterogeneous QoS models (DWSSGD_HQM) is presented for the first time. DWSSGD_HQM draws on and extends TOPSIS, which supports multiple decision-makers based on heterogeneous QoS models expressed in real numbers, interval numbers, triangular fuzzy numbers and intuitionistic fuzzy numbers respectively, and takes multi-periods QoS of above four types and weights of user and group expressed in above four data types in account. DWSSGD_HQM includes six main steps: convert heterogeneous QoS information into interval numbers, calculate weighted normalized decision-matrix, determine the group positive-ideal and group negative-ideal solutions, calculate the close-degrees of candidates, aggregate close-degrees of multi-periods for each decision-maker, and rank the alternatives. Finally, some experiments are given using actual QoS data to demonstrate the benefits and effectiveness of our approach.
孙家泽 耿国华 王曙燕 周明全
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60270-7
To improve the global convergence speed of social cognitive optimization (SCO) algorithm, a hybrid social cognitive optimization (HSCO) algorithm based on elitist strategy and chaotic optimization is proposed to solve constrained nonlinear programming problems (NLPs). The proposed algorithm partitions learning agents into three groups in proportion: elite learning agents, chaotic learning agents and common learning agents. The common learning agents work in the search way of traditional SCO, chaotic learning agents search via chaotic search (CS) algorithm based on Tent Map which helps to avoid the premature convergence, elite learning agents search via elitist selection which helps to improve the global searching performance. Additionally, a chaotic search process is incorporated into local searching operation so as to enhance the local searching efficiency in the neighboring areas of the feasible solutions. Simulation results on a set of benchmark problems show that the proposed algorithm has high optimization efficiency, good global performance, and stable optimization outcomes for constrained NLPs
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60271-9
Porno video recognition is important for Internet content monitoring. In this paper, a novel porno video recognition method by fusing the audio and video cues is proposed. Firstly, global color and texture features and local scale-invariant feature transform (SIFT) are extracted to train multiple support vector machine (SVM) classifiers for different erotic categories of image frames. And then, two continuous density hidden Markov models (CHMM) are built to recognize porno sounds. Finally, a fusion method based on Bayes rule is employed to combine the classification results by video and audio cues. The experimental results show that our model is better than six state-of-the-art methods.
郑桂妹 陈伯孝 杨明磊
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60272-0
曲志坚 柏琳 ZHANG Li-kun
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60273-2
尹良 尹斯星 王帅 张二青 洪卫军 李书芳
中国邮电高校学报(英文版), 2012, 19 (3). doi： 10.1016/S1005-8885(11)60274-4