本期目录

2008年 15卷 3期 刊出日期：2008-09-30



Wireless

Detection efficiency of cooperative spectrum sensing in cognitive radio network

陈星;别智松;吴伟陵

中国邮电高校学报(英文版), 2008, 15 (3). doi：

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Sensing the spectrum in a reliable and efficient manner is crucial to cognitive radio. To combat the channel fading suffered by the single radio, cooperative spectrum sensing is employed, to associate the detection of multiple radios. In this article, the optimization problem of detection efficiency under the constraint of detection probability is investigated, and an algorithm to evaluate the required radio number and sensing time for maximal detection efficiency is presented. To show the effect of cooperation on the detection efficiency, the proposed algorithm is applied to cooperative sensing using the spectral correlation detector under the Rayleigh flat fading channel.

Semidefinite programming detection for OvHDM signal

莫勇;杨星;李道本

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2494 ) PDF (145 KB)( 494 )

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Non-orthogonal time-frequency division multiplexing (NTFDM) transmission scheme has been proposed to further improve the bandwidth efficiency and overcome the drawbacks of the conventional orthogonal frequency division multiplexing (OFDM) method. Based on such approach, the fast signal detection algorithm, semidefinite programming (SDP) detection, has been studied. As the coefficient matrix tends to be ill conditioned, the modified SDP algorithm combined with successive interference cancellation (SIC) has been developed. The improved algorithm is a good tradeoff between performance and detection complexity. Simulation results show that the proposed algorithm can achieve better performance than cutting plane aided SDP method.

High throughput route selection in multi-rate wireless mesh networks

魏翼飞 郭湘黎 宋梅 宋俊德

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2493 ) PDF (0 KB)( 129 )

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Most existing Ad-hoc routing protocols use the shortest path algorithm with a hop count metric to select paths. It is appropriate in single-rate wireless networks, but has a tendency to select paths containing long-distance links that have low data rates and reduced reliability in multi-rate networks. This article introduces a high throughput routing algorithm utilizing the multi-rate capability and some mesh characteristics in wireless fidelity (WiFi) mesh networks. It uses the medium access control (MAC) transmission time as the routing metric, which is estimated by the information passed up from the physical layer. When the proposed algorithm is adopted, the Ad-hoc on-demand distance vector (AODV) routing can be improved as high throughput AODV (HT-AODV). Simulation results show that HT-AODV is capable of establishing a route that has high data-rate, short end-to-end delay and great network throughput.

Cross-layer combining of power control and adaptive modulation with truncated ARQ for cognitive radios

程世伦;杨震

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2390 ) PDF (195 KB)( 376 )

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To maximize throughput and to satisfy users’ requirements in cognitive radios, a cross-layer optimization problem combining adaptive modulation and power control at the physical layer and truncated automatic repeat request at the medium access control layer is proposed. Simulation results show the combination of power control, adaptive modulation, and truncated automatic repeat request can regulate transmitter powers and increase the total throughput effectively.

Cell search scheme for long-term evolution of TD-SCDMA system

苏环;张建;华李克

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2412 ) PDF (445 KB)( 443 )

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Cell search is an important aspect for 3G long-term evolution (LTE). This article deals with cell search in the time-division-synchronou code-division multiple access (TD-SCDMA) LTE system. On the basis of the synchronization channel (SCH) and cell specific reference symbols (CSRSs), the proposed cell search procedure includes five stages: frame detection and coarse timing, coarse carrier frequency offset (CFO) estimation, fine timing, fine CFO estimation, and cell identification. The key features of the proposed method are as follows: first, the neighboring three cells’ CSRSs are frequency division multiplexed (FD) to mitigate inter-cell interference. Second, the frequency domain differential cross-correlation, computed from CSRSs are maximally ratio combined for cell identification. Finally, the large set Kasami sequences are quadrature phase shift key (QPSK) modulated to be cell specific sequences (CSSs), to support a large number of target cells. Simulations show that the FD method is better than the code division multiplexed (CD) method.

Suboptimal resource allocation with MMSE detector for grouped MC-CDMA systems

王亚琛;张鹏;刘元安;李娜

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2282 ) PDF (289 KB)( 479 )

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This article puts forward two novel user-grouping algorithms for grouped multi-carrier (MC)-code division multiple access (CDMA) systems. As is well known, the adaptive assignment for user-grouping plays an important role for link quality of multi-access transmissions. In the study, the capacity-maximizing problem of user-grouping is formulated. By using the Kuhn-Tucker condition, the optimal criterion is deduced and found to have a similar form with signal to noise plus interference (SINR). However SINR includes the signal power that can only be determined after user-grouping. Therefore the optimal criterion will lead to an impractical application. To deal with it, the user’s equivalent SINR for minimum mean square error (MMSE) detector is proposed and served as a suboptimal assignment criterion, based on which two kinds of user-grouping algorithms are proposed. In the algorithms, only partial channel information is needed at the base station, which saves a large part of the bandwidth occupied by feedback information. Computer simulations have evaluated an excellent performance of the proposed algorithms at both link quality and data rate. Meanwhile, the proposed algorithms have lower implementation complexity for practical reality.

Adaptive beam forming for time-variant channels with a multi-beam antenna

蒋泽 梅媛媛 阮巍

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2448 ) PDF (287 KB)( 393 )

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A multi-beam adaptive antenna is investigated by considering the adaptive beam forming performance for time-variant channels on the focus of mobile to base station or reverse link. This antenna is constructed by Fresnel zone phase-correcting plane (FZP) focusing element and uniformly spaced feeds array. An estimator for the beamforming weight vector in the presence of angle spreads is derived using a code filtering approach. Owing to the time-varying nature of the channels, a recursive method for computing and tracking the above optimal weight vector solution that is easy to implement is applied. The effects of angle spread, maximum Doppler frequency, and forgetting factor are studied. Simulation results showed that this type of adaptive antenna is capable of performing adaptive beam forming for time-variant channels effectively.

Multiuser subcarriers and bit allocation combining adaptive mapping for SC-FDMA system

张宇眉 辛雨 杨大成

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2338 ) PDF (296 KB)( 450 )

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In this article, a multiuser single carrier frequency division multiple access (SC-FDMA) system is considered, based on which an adaptive subcarrier and bit allocation algorithm is investigated. The algorithm has been used to achieve a subcarrier mapping mode in this system, which combines the advantages of single- and multi-carrier transmissions, such as, low peak to average power ratio, orthogonality of signals of different users, and low complexity. Simulation results show that it has a similar performance as that of the adaptive allocation algorithm in the orthogonal frequency division multiple (OFDM) system and the proposed mapping mode has a performance gain over the two existing mapping modes at the link level.

Partner selection strategies in cooperative wireless networks with optimal power distribution

张倩倩 高伟东 彭木根 王文博

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2731 ) PDF (186 KB)( 427 )

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There have been several results that illustrate the best performance that a network can get through cooperation of relay nodes. For practical purposes, not all nodes in the network should be involved at the same time in every transmission. Therefore, optimal partner selection protocols in cooperative wireless networks are believed to be the first important thing that should be paid attention to. This problem in our article is considered in the context of regenerative nodes and non-altruistic cooperation (no pure relay exists; all nodes have their own data to transmit). For each transmission, the protocol must provide the user (source node) a ‘best partner’ (relay node) to cooperate with (for network simplicity and less transmission signals here, assume that each user has only one cooperative node). A criterion is essentially needed when defining what a ‘best partner’ is; in this article, two factors, i.e,. the successful transmission probability and the transmission power, are considered. Three optimal partner selection strategies with different goals are proposed and analyzed respectively. The simulation results show that these are all supposed to be good tradeoffs between power consumption and transmission performance.

Artificial Intelligence

Packet track and traceback mechanism against denial of service attacks

李莉 沈苏彬

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2470 ) PDF (243 KB)( 481 )

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The denial of service attack is a main type of threat on the Internet today. On the basis of path identification (Pi) and Internet control message protocol (ICMP) traceback (iTrace) methods, a packet track and traceback mechanism is proposed, which features rapid response and high accuracy. In this scheme, routers apply packet marking scheme and send traceback messages, which enables the victim to design the path tree in peace time. During attack times the victim can trace attackers back within the path tree and perform rapid packet filtering using the marking in each packet. Traceback messages overcome Pi’s limitation, wherein too much path information is lost in path identifiers; whereas path identifiers can be used to expedite the design of the path-tree, which reduces the high overhead in iTrace. Therefore, our scheme not only synthesizes the advantages but also compromises the disadvantages of the above two methods. Simulation results with NS-2 show the validity of our scheme.

DDoS detection based on wavelet kernel support vector machine

杨明慧;王汝传

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2942 ) PDF (221 KB)( 729 )

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To enhance the detection accuracy and deduce false positive rate of distributed denial of service (DDoS) attack detection, a new machine learning method was proposed. With the analysis of support vector machine (SVM) and the wavelet kernel function theory, an admissive support vector kernel, which is a wavelet kernel constructed in this article, implements the combination of the wavelet technique with SVM. Then, wavelet support vector machine (WSVM) is applied to DDoS attack detections and as a classifying means to test the validity of the wavelet kernel function. Simulation experiments show that under the same conditions, the predictive ability of WSVM is improved and the computation burden is alleviated. The detection accuracy of WSVM is higher than the traditional SVM by about 4%, while its false positive is lower than the traditional SVM. Thus, for DDoS detections, WSVM shows better detection performance and is more adaptive to the changing network environment.

Pseudo-random sequence generator based on the generalized Henon map

郑凡 田小建 宋静怡 李雪妍

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2824 ) PDF (507 KB)( 672 )

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By analysis and comparison of several chaotic systems that are applied to generate pseudo-random sequence, the generalized Henon map is proposed as a pseudo-random sequence generator. A new algorithm is created to solve the problem of non-uniform distribution of the sequence generated by the generalized Henon map. First, move the decimal point of elements in the sequence to the right; then, cut off the integer; and finally, quantify it into a binary sequence. Statistical test, security analysis, and the application of image encryption have strongly supported the good random statistical characteristics, high linear complexity, large key space, and great sensitivity of the binary sequence.

Network

Resource allocation using time division multiple access over wireless relay networks

戴沁芸 戎璐 胡宏林 苏钢

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2533 ) PDF (278 KB)( 434 )

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This article considers a wireless network consisting of multiple sources that communicate with the corresponding destination utilizing a single half-duplex relay, whereas, the sources use the relay opportunistically. By integrating the information theory with the concept of effective capacity, this article proposes a dynamic time allocation strategy over the wireless relay network that aims at maximizing the relay network throughput, subject to a given delay quality of service (QoS) constraint, where time division multiple access (TDMA) is applied in the relay network. The simulation results show that the proposed allocation strategy can significantly improve the effective capacity as compared to the traditional equal time allocation strategy.

NHRPA: a novel hierarchical routing protocol algorithm for wireless sensor networks

程宏兵 杨庚 胡素君

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2596 ) PDF (319 KB)( 541 )

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Considering severe resources constraints and security threat of wireless sensor networks (WSN), the article proposed a novel hierarchical routing protocol algorithm. The proposed routing protocol algorithm can adopt suitable routing technology for the nodes according to the distance of nodes to the base station, density of nodes distribution, and residual energy of nodes. Comparing the proposed routing protocol algorithm with simple direction diffusion routing technology, cluster-based routing mechanisms, and simple hierarchical routing protocol algorithm through comprehensive analysis and simulation in terms of the energy usage, packet latency, and security in the presence of node compromise attacks, the results show that the proposed routing protocol algorithm is more efficient for wireless sensor networks.

Status adaptive routing with delayed rebroadcast scheme in AODV-based MANETs

李亭 唐瑞博 纪红

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 3440 ) PDF (231 KB)( 474 )

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An efficient solution is proposed in this article to determine the best reliable route and to prolong the lifetime of the mobile Ad-hoc networks (MANETs). In the proposed solution, the route discovery process of the Ad-hoc on-demand distance vector routing protocol (AODV) has been modified using a novel delayed rebroadcast scheme. It combines the shortest route selection criterion of AODV with the real network status including the wireless link quality, the remaining power capacity, as well as the traffic load at each node. Simulation results show that the proposed scheme can significantly extend the network lifetime and provide fewer packet losses than the conventional AODV protocol.

OFDM

Cross-layer resource allocation for QoS guarantee with finite queue constraint in multirate OFDMA wireless networks

徐海博 田辉 冯媛

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2756 ) PDF (297 KB)( 383 )

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Efficient radio resource allocation is essential to provide quality of service (QoS) for wireless networks. In this article, a cross-layer resource allocation scheme is presented with the objective of maximizing system throughput, while providing guaranteed QoS for users. With the assumption of a finite queue for arrival packets, the proposed scheme dynamically allocates radio resources based on user’s channel characteristic and QoS metrics derived from a queuing model, which considers a packet arrival process modeled by discrete Markov modulated Poisson process (dMMPP), and a multirate transmission scheme achieved through adaptive modulation. The cross-layer resource allocation scheme operates over two steps. Specifically, the amount of bandwidth allocated to each user is first derived from a queuing analytical model, and then the algorithm finds the best subcarrier assignment for users. Simulation results show that the proposed scheme maximizes the system throughput while guaranteeing QoS for users.

Performance of a recursive algorithm for polynomial predistorter design

许灵军 吴晓光 王勇 张平

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2557 ) PDF (325 KB)( 388 )

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In this article, based on least square estimation, a recursive algorithm for indirect learning structure predistorter is introduced. Simulation results show that of all polynomial predistorter nonlinear terms, higher-order (higher than 7th-order) nonlinear terms are so minor that they can be omitted in practical predistorter design. So, it is unnecessary to construct predistorter with higher-order polynomials, and the algorithm will always be stable. Further results show that even when 15th-order polynomial model is used, the algorithm is convergent after 10 iterations, and it can improve out-band spectrum of 20 MHz bandwidth signal by 64 dB, with a 1.2×1011 matrix condition number.

MIMO

SAGE based iterative receiver for joint synchronization and channel estimation in uplink MIMO-OFDMA systems

姜政 秦晓芳 张欣 杨大成

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 3133 ) PDF (236 KB)( 431 )

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A new Turbo iterative receiver structure is proposed for the uplink multiple-input multiple-output orthogonal frequency division multiple access (MIMO-OFDMA) systems. The space-alternating generalized expectation-maximization (SAGE) algorithm is naturally embedded in the framework of iterative receiver to perform synchronization and detection using the Turbo detector outputs. In each iteration, the expectation step intends to remove the multiple access interference (MAI) caused by other asynchronous users, and the maximization step is utilized to estimate the required parameters (i.e., timing offset, carrier frequency offset, channel state information, etc.) sequentially for each user. Simulation results show that the proposed algorithm can approach the performance of ideal receiver closely, while the processing complexity is rather lower than the conventional detectors.

Grassmannian precoding MU-MIMO scheme

方舒 李立华 张平

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2729 ) PDF (297 KB)( 413 )

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In this article, a Grassmannian precoding multiuser multiple-input multiple-output (MU-MIMO) scheme for downlink transmission is proposed. The proposed MU-MIMO scheme will perform scheduling and precoding simultaneously at the base station, to obtain both the multiuser diversity gain and the precoding gain, to maximize the system capacity. The precoding method is related to Grassmannian precoding, which extends the point-to-point single-user Grassmannian precoding to point-to-multipoint multiuser Grassmannian precoding. It provides further significant system capacity enhancement than the single user MIMO (SU-MIMO) system and also outperforms the block diagonalization (BD) algorithm under the same simulation environment.

Artificial Intelligence

Polyclonal clustering algorithm and its convergence

马力 焦李成 白琳 陈长国

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2597 ) PDF (313 KB)( 526 )

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Being characteristic of non-teacher learning, self-organization, memory, and noise resistance, the artificial immune system is a research focus in the field of intelligent information processing. Based on the basic principles of organism immune and clonal selection, this article presents a polyclonal clustering algorithm characteristic of self-adaptation. According to the core idea of the algorithm, various immune operators in the artificial immune system are employed in the clustering process; moreover, clustering numbers are adjusted in accordance with the affinity function. Introduction of the recombination operator can effectively enhance the diversity of the individual antibody in a generation population, so that the searching scope for solutions is enlarged and the premature phenomenon of the algorithm is avoided. Besides, introduction of the inconsistent mutation operator enhances the adaptability and optimizes the performance of local solution seeking. Meanwhile, the convergence of the algorithm is accelerated. In addition, the article also proves the convergence of the algorithm by employing the Markov chain. Results of the data simulation experiment show that the algorithm is capable of obtaining reasonable and effective cluster.

Microelectronics

RS trigger based relaxation oscillator for temperature measurement circuit

邹志革 邹雪城 简文翔 雷鑑铭

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2383 ) PDF (361 KB)( 377 )

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Resistance-to-time converter is always used for digital temperature measurement. An reset-set (RS) trigger based, relaxation oscillator based temperature measurement circuit, which is used to convert the change of thermistor sensor into a frequency signal for later processing, has been presented in this article. The RS trigger, which is composed of two inverters designed with distinct logical transition threshold voltages by changing the metal-oxide-semiconductor (MOS) transistor gains, has the same function as the Schmitt trigger in the relaxation oscillator. The advantage of the RS trigger based Schmitt trigger is that it reduces the dependence to supply voltage, chip temperature, and process variation. This temperature measurement circuit has been applied in a clinical thermometer chip that can measure temperature to an accuracy of better than 0.05℃ down to 1.1 V battery voltage. It is fabricated in 0.5 double metal single poly complementary MOS (CMOS) process.

Artificial Intelligence

Enhanced solutions for resource conflict in GMPLS controlled optical network

黄治同 华一强 陆月明 纪越峰 徐大雄

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 3186 ) PDF (379 KB)( 392 )

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This article discusses the issue of resource conflict in the generalized multi-protocol label switching (GMPLS) controlled optical network. Based on the analysis of the current random rebuilding mechanism and its drawbacks, this article presents two enhanced solutions for improvement, namely, the priority-based resource allocation mechanism and the network management system (NMS) based sequential resource allocation mechanism. Experimental results show that the presented mechanisms perform better than the original random rebuilding solution in terms of the connection setup/recovery time and successful rate.

Parallel Programming

Approach of generating parallel programs from parallelized algorithm design strategies

万剑怡 李晓英

中国邮电高校学报(英文版), 2008, 15 (3). doi：

摘要 ( 2203 ) PDF (209 KB)( 412 )

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Today, parallel programming is dominated by message passing libraries, such as message passing interface (MPI). This article intends to simplify parallel programming by generating parallel programs from parallelized algorithm design strategies. It uses skeletons to abstract parallelized algorithm design strategies, as well as parallel architectures. Starting from problem specification, an abstract parallel abstract programming language+ (Apla+) program is generated from parallelized algorithm design strategies and problem-specific function definitions. By combining with parallel architectures, implicity of parallelism inside the parallelized algorithm design strategies is exploited. With implementation and transformation, C++ and parallel virtual machine (CPPVM) parallel program is finally generated. Parallelized branch and bound (B&B) algorithm design strategy and parallelized divide and conquer (D & C) algorithm design strategy are studied in this article as examples. And it also illustrates the approach with a case study.