本期目录

2011年 18卷 1期 刊出日期：2011-02-28



Wireless

On the MAC-BC duality of multiuser non-regenerative MIMO relay systems

李根 王莹 弓风 吴彤 张平

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60020-9

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Multiple input multiple output (MIMO) relaying techniques can greatly improve the spectral efficiency and extend network coverage for future wireless systems. This article investigates a multiuser MIMO relay channel, where a base station (BS) with multiple antennas communicates with multiple mobile stations (MS) via a relay station (RS) with multiple antennas. The RS applies linear processing to the received signal and then forwards the processed signal. The dual channel conditions between MIMO relay multiple access channel (MAC) and broadcast channel (BC) are first developed for single-relay scenario with white Gaussian noise. Then the MAC-BC duality for MIMO relay systems is established by proving that the capacity region of MIMO relay MAC is equal to that of dual MIMO relay BC under the same total network transmit power constraint. In addition, the duality is also extended to multi-relay scenario with arbitrary noise. Finally, several simple general numerical examples are provided to better illustrate the effectiveness of the MIMO relay MAC-BC duality

Optimal power allocation for two-way relaying over OFDM using physical-layer network coding

李富年 朱光喜 王德胜

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60021-0

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In this paper, a network scenario of two-way relaying over orthogonal frequency division multiplexing (OFDM) is considered, in which two nodes intend to exchange the information via a relay using physical-layer network coding (PLNC). Assuming that the full channel knowledge is available, an optimization problem, which maximizes the achievable sum rate under a sum-power constraint, is investigated. It is shown that the optimization problem is non-convex, which is difficult to find the global optimum solution in terms of the computational complexity. In consequence, a low-complexity optimal power allocation scheme is proposed for practice implementation. A link capacity diagram is first employed for power allocation on each subcarrier. Subsequently, an equivalent relaxed optimization problem and Karush-Kuhn-Tucker (KKT) conditions are developed for power allocation among each subcarrier. Simulation results demonstrate that the substantial capacity gains are achieved by implementing the proposed schemes efficiently with a low-complexity computational effort.

Peroformance analysis of decode-and-forward MIMO relay channels with OSTBCs

胡春静 陈书平 王文博 赵冬

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60022-2

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Performance analysis is presented for multiple-input multiple-output (MIMO) relay channels employing transmit antenna diversity with orthogonal space-time block codes (OSTBCs), where the source and the destination are equipped with Ns and Nd antennas, and communicate with each other with the help of a multiple-antenna relay operating in decode-and-forward (DF) mode. Over independent, not necessarily identical Rayleigh fading channels, exact closed-form symbol error rate (SER) expressions are derived for various digital modulation formats for both the OSTBC transmission with and without the direct link. The moment generating functions (MGFs) for overall system signal-noise ratios (SNRs) are also derived, based on which we present a unified SER analysis. The analysis shows that full spatial diversity order can be achieved for the DF MIMO relay channel by adopting OSTBC transmissions and maximal ratio combining (MRC) receptions. All the analytical results are confirmed through comparison with the results obtained using Mento Carlo simulations.

Distance geometric constraint filtering algorithm and its application in UWB location

赵军辉

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60023-4

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This paper proposed a novel wireless location algorithm based on distance geometry (DG) constraint filtering for the time of arrival (TOA) of the signal (namely as DG-TOA). Filtering and processing of the observed data and leading to the mathematical formulas based on DG-TOA algorithm are applied to location, also play crucial rules. Simulation results show that the proposed DG-TOA algorithm can provide more valid observation data and be more precise than least square estimate (LSE) algorithm in dense, multi-route, indoor circumstances with the ranging estimation error.

Layered space time codes and capacity analysis in correlated fading channels with distributed antenna system

熊飞 张建华 张平

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60024-6

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In this paper we have investigated the performance of downlink generalized distributed antenna system (GDAS). Under the assumption of spatial correlated fading conditions, we have derived the numeric expression of correlated coefficients according to series of Bessel function, and have lifted the range restriction of the mean angle of incident. Moreover, the architecture of distributed generalized layered space time codes (GLST) has been considered in order to achieve both multiplexing gain and diversity gain while we have used basis vector from null space instead of orthogonal set to obtain the same system performance but with lower complexity. Furthermore, in order to maximize the capacity, Gerschgorin circles based fast antenna selection algorithms have been evaluated including a discussion of those simulation results.

Flexible paired-orthogonal codes for multi-user MIMO-OFDM

王亚琛 樊燕红 马晓凤 李晔

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60025-8

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The work proposes two novel spreading codes, called extensive double-orthogonal code (EDOC) and flexible paired-orthogonal code (FPOC), for multi-user downlink multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. The goal of code designs is to obtain an improved bit error rate (BER) performance without loss of bandwidth efficiency. The code designs achieve space diversity by employing multiple antennas at both transmit ends and receive ends. Codes are reasonably spread into time, frequency and space domain. The proposed codes are attractively characterized with length flexibility, which breaks the “power of two” constraint. The simulation results indicate that the proposed codes improve overall BER performance, by exploiting space diversity gains. The flexibility in code length also results in high spectral efficiency.

Networks

Message redundancy removal of multi-copy routing in delay tolerant MANET

于海征 边红 马建峰

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60026-X

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This article puts forward a new scheme to control message redundancy efficiently in delay tolerant mobile Ad-hoc networks (MANET). The class of networks generally lacks end-to-end connectivity. In order to improve the efficiency that messages are delivered successfully, multiple message copies routing protocols are usually used, but the network load is increased due to a large number of message redundancies. In the study, by using counter method, every node adds an encounter counter based on epidemic routing scheme. The counter records the number which the node encounters other nodes with the same message copy. If the counter of a node reaches the installed threshold, the node removes the copy. Theoretical analysis gives a lower bound of threshold in delay tolerant MANET. According to the lower bound of threshold, a rational threshold is installed in real environment. With proposed scheme message copies decrease obviously and are removed completely finally. The successful delivery efficiency is still the same as epidemic routing and the redundant copies are efficiently controlled to a relatively low level. Computer simulations give the variation of message copies concerning different thresholds in fast and slow mobility scenes.

Energy saving with node sleep and power control mechanisms for wireless sensor networks

高德云

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60027-1

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Energy efficiency sleep scheduling in wireless sensor networks is one of the most crucial technologies. In this paper, we propose a simple and feasible synchronous node sleeping and waking mechanisms for small scale wireless sensor networks. Sensor nodes are divided into forwarding nodes and listening nodes. Beacon frame containing sleep command from the coordinator can be forwarded to listening nodes via forwarding nodes. All the nodes in the network can enter sleep at about the same time. Through such network synchronization mechanisms, we can realize synchronous sleep and wake of the entire network. Furthermore, a new power control scheme based on routing protocol (PCBRP) in the medium access control (MAC) layer is proposed. It operates with the help of routing protocol and calculates optimal transmission power according to the distance between neighbor nodes. A mapping table including optimal transmission power and node address is established during the route building procedure. The transmission power can be obtained by searching the table with the address of next-hop neighbor in subsequent data transmissions. The proposed mechanisms are implemented in sensor nodes and are evaluated in a test-bed. The analysis and evaluation based on the experimental results confirm that the proposed energy-saving mechanisms are feasible and effective.

Cubic metric improvement of aggregated carriers for downlink transmission in LTE-advanced

张少欣 周俊 朱洪波 朱琦

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60028-3

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To meet long term evolution-advanced (LTE-A) requirements of wider bandwidth and maintain backwards compatibility with LTE release 8 (Rel-8) simultaneously，carrier aggregation has been agreed by the third generation partnership project (3GPP). High cubic metric (CM) values and peak-to-average power ratio (PAPR) of aggregated component carriers (CCs) exists as an unpleasant issue for both uplink and downlink (DL) transmission. For DL transmission，to use distinct cell ID per DL CC to generate DL reference signal (RS) sequence can mitigate this problem but will cause some other issues on the corresponding uplink carrier. This article proposes two approaches to solve the problem of high CM/PAPR by introducing new variables to change the cell-specific DL RS sequence. In both methods, same cell identifier (cell ID) is allocated to all DL CCs. Simulation results show the performance improvements and prove the effectivity of our proposed approaches.

Research on physical layer traffic management schemes in serial RapidIO interconnect

张勇 王勇 张平

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60029-5

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A traffic management scheme in serial RapidIO (SRIO) interconnect is proposed to deal with the performance degradation caused by noise and electromagnetic interference (EMI), which is generated by hardly avoidable errors of hardware implementation and tough working environment. The main idea of this scheme includes adaptive speed transition and freeze-acknowledgement (freeze-ACK). Adaptive speed transition can improve throughput and reduce delay in high bit error rate (BER) environment. Simultaneously, freeze-ACK is adopted to conquer frequent usage of feedback channel. Simulation shows that the scheme of combining adaptive speed transition with freeze-ACK offers great performance improvement in SRIO network.

Virtual channel load-balanced routing algorithm for Torus networks

王亚刚 杜慧敏 沈绪榜

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60030-1

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In order to improve the network performance furthermore, a routing algorithm for 2D-Torus is investigated from the standpoint of load balance for virtual channels. The 2D-Torus network is divided into two virtual networks and each physical channel is split into three virtual channels. A novel virtual channel allocation policy and a routing algorithm are proposed, in which traffic load is distributed to those three virtual channels in a more load-balanced manner by introducing a random parameter. Simulations of the proposed algorithm are developed with a SystemC-based test bench. The results show that compared with the negative first for Torus networks (NF-T) algorithm, the proposed algorithm can achieve better performance in terms of network latency and throughput under different traffic patterns. It also shows that a routing algorithm with load balance for virtual channels can significantly improve the network performance furthermore.

Artificial Intelligence

New chaos M-ary modulation method and its application in communications

付永庆 张芳

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60031-3

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At present, chaotic communications have been widely studied. However, these researches mainly focus on the binary systems while the researches of M-ary chaotic communications are not extensive. To change the situation, a chaos M-ary modulation method based on phase plane partition of Hamilton map is proposed. Firstly, the chaotic model of Hamilton map and its phase plane features are described, and then the way of creating the chaos M-ary modulation is discussed. Next, to evaluate the proposed method, the system simulation results and analysis are given. Finally, the chaos M-ary modulation method is applied to communications.

Application of kernel methods in signals modulation classification

周欣 吴瑛 王大磊

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60032-5

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A new approach to common signals classification of relevance vector machine (RVM) was presented and two signal classifiers based on kernel methods of support vector machine (SVM) and RVM were compared and analyzed. First several robust features of signals were extracted as the input of classifiers, then the kernel thought was used to map feature vectors impliedly to the high dimensional feature space, and multi-class RVM and SVM classifiers were designed to complete AM, CW, SSB, MFSK and MPSK signals recognition. Simulation result showed that when chose proper parameter, RVM and SVM had comparable accuracy but RVM had less learning time and basis functions. The classification speed of RVM is much faster than SVM.

Orthogonal isometric projection for face recognition

卢官明 左加阔

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60033-7

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Isometric projection (IsoProjection) is a linear dimensionality reduction method, which explicitly takes into account the manifold structure embedded in the data. However, IsoProjection is non-orthogonal, which makes it extremely sensitive to the dimensions of reduced space and difficult to estimate the intrinsic dimensionality. The non-orthogonality also distorts the metric structure embedded in the data. This paper proposes a new method called orthogonal isometric projection (O-IsoProjection), which shares the same linear character as IsoProjection and overcomes the metric distortion problem of IsoProjection. Similar to IsoProjection, O-IsoProjection firstly constructs an adjacency graph which can reflect the manifold structure embedded in the data and the class relationship between the sample points of face space, and then obtains the projections by preserving such a graph structure. Different from IsoProjection, O-IsoProjection requires the basis vectors to be orthogonal, and the orthogonal basis vectors can be calculated by iterative way. Experimental results on ORL and Yale databases show that O-IsoProjection has better recognition rate for face recognition than Eigenface, Fisherface and IsoProjection.

Fingerprint singular points extraction based on the properties of orientation model

苏菲 孙鹏 王波涛 蔡安妮

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60034-9

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A novel method for fingerprint singular points extraction including location and orientation is proposed based on some properties of the orientation field models. Singular points are located by clustering the results of corner detection. Then, through examining the sub-block orientation fields at a number of selected positions on concentric circles centered about the located singular point, an iterative method based on the orientation differences is proposed to compute the orientation of the core point. Experimental results on NIST4 and FVC2002 four databases demonstrate the proposed method can consistently locate singular points with the high accuracy. The location and orientation of the detected singular points can be used for alignment (translation and rotation) parameters in fingerprint matching.

Others

3D augmented reality teleoperated robot system based on dual vision

高欣 胡欢 贾庆轩 孙汉旭 宋荆洲

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60035-0

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A 3D augmented reality navigation system using stereoscopic images is developed for teleoperated robot systems. The accurate matching between the simulated model and the video image of the actual robot can be realized, which helps the operator to accomplish the remote control task correctly and reliably. The system introduces the disparity map translation transformation method to take parallax images for stereoscopic displays, providing the operator an immersive 3D experience. Meanwhile, a fast and accurate registration method of dynamic stereo video is proposed, and effective integration of a virtual robot and the real stereo scene can be achieved. Preliminary experiments show that operation error of the system is maintained at less than 2.2 mm and the average error is 0.854 7, 0.909 3 and 0.697 2 mm at x, y, z direction respectively. Lots of experiments such as pressing the button, pulling the drawer and so on are also conducted to evaluate the performance of the system. The feasibility studies show that the depth information of structure can be rapidly and recognized in remote environment site. The augmented reality of the image overlay system could increase the operating accuracy and reduce the procedure time as a result of intuitive 3D viewing.

Multi-policy threshold signature with distinguished signing authorities

王锋 周由胜 谷利泽 郑世慧 杨义先

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60036-2

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Threshold signature plays an important role to distribute the power of a single authority in modern electronic society. In order to add functions and improve efficiency of threshold signatures, a multi-policy threshold signature scheme with distinguished signing authorities is proposed. In the scheme two groups can sign and verify each other, so the scheme is two-way signing and verifying. Moreover, the threshold values of the two groups can change with the security classification of the signing document, every discretionary signatory only signs a small part of the document instead of the whole one, so the bandwidth of data transmission for group signature construction can be reduced and the size of group signature is equivalent to that of any individual signature.

Design of new format for mass data compression

覃健诚 白中英

中国邮电高校学报(英文版), 2011, 18 (1). doi： 10.1016/S1005-8885(10)60037-4

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In the field of lossless compression, most kinds of traditional software have some shortages when they face the mass data. Their compressing abilities are limited by the data window size and the compressing format design. This paper presents a new design of compressing format named ‘CZ format’ which supports the data window size up to 4 GB and has some advantages in the mass data compression. Using this format, a compressing shareware named ‘ComZip’ is designed. The experiment results support that ComZip has better compression ratio than WinZip, Bzip2 and WinRAR in most cases, especially when GBs or TBs of mass data are compressed. And ComZip has the potential to beat 7-zip in future as the data window size exceeds 128 MB.