本期目录

2008年 15卷 4期 刊出日期：2008-12-30



Wireless

Efficient channel blind estimator for multiuser system with conjugate cyclostationarity

周克,曹士珂，张力军

中国邮电高校学报(英文), 2008, 15 (4). doi： 1005-8885 (2008) 01-0001-05

摘要 ( 2279 ) PDF (344 KB)( 403 )

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The problem of blind channel identification in a multiuser system is considered in this article. For this purpose, a blind identification algorithm is proposed based on the conjugate cyclostationarity of the received signal. The new approach contains a two-stage identification procedure. First, the separation technique in the cyclic domain is used to separate the second-order cyclic statistics for each user. Second, a subspace algorithm based on the rational subspace theory is exploited to estimate the desired channel. Theoretical analysis and simulation results show that this algorithm is suitable for a multiuser system. Compared with other methods, the algorithm shows good performance even in a bad situation when the number of users is large and the diversity condition is unavailable.

Over-sampling basis expansion model aided channel estimation for OFDM systems with ICI

刘思杨,刘元安,王飞飞,XIE Gang,张然然

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 3079 ) PDF (307 KB)( 510 )

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The rapid variation of channel can induce the intercarrier interference in orthogonal frequency-division multiplexing (OFDM) systems. Intercarrier interference will significantly increase the difficulty of OFDM channel estimation because too many channel coefficients need be estimated. In this article, a novel channel estimator is proposed to resolve the above problem. This estimator consists of two parts: the channel parameter estimation unit (CPEU), which is used to estimate the number of channel taps and the multipath time delays, and the channel coefficient estimation unit (CCEU), which is used to estimate the channel coefficients by using the estimated channel parameters provided by CPEU. In CCEU, the over-sampling basis expansion model is resorted to solve the problem that a large number of channel coefficients need to be estimated. Finally, simulation results are given to scale the performance of the proposed scheme.

Optimal power allocation to minimize SER for multinode amplify-and-forward cooperative communication systems

林霏,刘喜梅,罗涛,乐光新

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 3039 ) PDF (278 KB)( 470 )

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An optimal power allocation (OPA) method with mean channel gains is proposed for a multinode amplify-and-forward cooperative communication system. By making use of M-PSK modulation, a closed-form symbol-error-rate (SER) formulation and corresponding upper bound are first derived. Subsequently the OPA method is utilized to minimize the SER. Comparison of the SER of the proposed OPA method with that of the equal power allocation (EPA) method, shows that the SER of both methods, which is approximately optimal performance, is almost the same when relays are near the source. OPA outperforms the EPA when the relays are near the middle between the source and destination or near the destination. The proposed OPA method depends only on the ratio of mean channel gains of the source-to-relay to those of the relay-to-destination. Extensive simulations are performed to validate the theoretical results.

Layered MAP algorithm for MIMO ISI channels

莫勇,周兴围,李道本

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2967 ) PDF (181 KB)( 403 )

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The layered maximum a posteriori (L-MAP) algorithm has been proposed to detect signals under frequency selective fading multiple input multiple output (MIMO) channels. Compared to the optimum MAP detector, the L-MAP algorithm can efficiently identify signal bits, and the complexity grows linearly with the number of input antennas. The basic idea of L-MAP is to operate on each input sub-stream with an optimum MAP sequential detector separately by assuming the other streams are Gaussian noise. The soft output can also be forwarded to outer channel decoder for iterative decoding. Simulation results show that the proposed method can converge with a small number of iterations under different channel conditions and outperforms other sub-optimum detectors for rank-deficient channels.

Linear beamformer schemes with simple relay selection in MIMO relay networks

孟庆民,潘甦,ZHENG Bao-yu,朱洪波,尤肖虎

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2280 ) PDF (291 KB)( 388 )

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This article considers a wireless multi-hop/mesh network where single multi-antenna source-destination pair communicates through a selected relay subset using simple relay selection under the constraint of fixed relay’s number. Compared with random selection, the simple relay selection can yield certain capacity advantages while linear zero-forcing (ZF) receiver and linear beamformer are considered at the relay. For match-filter (MF) beamformer and amplified-and-forward (AF) beamformer with a fixed number of relays, the capacities are given. Furthermore, we extend the simple selection methods to the relaying scheme with orthogonal-triangular (QR) beamformer and investigate these linear beamformer schemes over spatially correlated multi-input multi-output (MIMO) links for both the backward and forward channel over the two-hop MIMO relay networks.

Improving coarse frame synchronization by UE-UE interference for OFDMA-TDD systems

朱源,王纯业,杨大成

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2191 ) PDF (260 KB)( 395 )

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This article studies the coarse frame synchronization of orthogonal frequency division multiplexing access-time division duplex (OFDMA-TDD) systems and proposes a new method to improve coarse frame synchronization performance. The new method utilizes the user equipment to user equipment (UE-UE) interference, which is usually considered as a specific challenge for time division duplex (TDD) and also as implicit frame boundary information to enhance coarse frame synchronization performance. Numerical results show the synchronization performance is improved by the new method.

Decoding OvTDM with sphere-decoding algorithm

金鑫,李道本

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 3067 ) PDF (168 KB)( 422 )

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Overlapped time division multiplexing (OvTDM) is a new type of transmission scheme with high spectrum efficiency and low threshold signal-to-noise ratio (SNR). In this article, the structure of OvTDM is introduced and the sphere-decoding algorithm of complex domain is proposed for OvTDM. Simulations demonstrate that the proposed algorithm can achieve maximum likelihood (ML) decoding with lower complexity as compared to traditional maximum likelihood sequence demodulation (MLSD) or viterbi algorithm (VA).

Packet scheduling for OFDMA based relay networks

韩静,龚平,吴伟陵

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 3549 ) PDF (254 KB)( 676 )

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The combination of relay networks with orthogonal frequency division multiple access (OFDMA) has been proposed as a promising solution for the next generation wireless system. Considering different traffic classes and user quality of service (QoS), three efficient scheduling algorithms are introduced in such networks. The round-robin (RR) algorithm in relay networks serves as a performance benchmark. Numerical results show that the proposed algorithms achieve significant improvement on system throughput and decrease system packet loss rate, compared with the RR and absence of relaying system (traditional network). Furthermore, comparisons have been carried out among the three proposed algorithms.

Indoor channel characteristics based on wideband MIMO measurements at 5.25 GHz

高新颖，张建华，张平

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2352 ) PDF (380 KB)( 453 )

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Extensive indoor channel measurements were conducted in Beijing with wideband multiple-input multiple-output (MIMO) sounder at 5.25 GHz. Both line-of-sight (LOS) and non-line-of-sight (NLOS) propagation were measured in the indoor office and hotspot scenarios. On the basis of measured data, statistical channel characteristics are presented in this article, including the empirical path loss (PL) models, three excess delay parameters, circular azimuth spread (CAS), and circular elevation spread (CES). Comparative analysis of different propagation mechanisms in two scenarios is conducted. These values are significant for indoor coverage and technical research of MIMO and orthogonal frequency division multiplexing (OFDM) for the international mobile telecommunications-advanced (IMT-Advanced) system.

Multi-branch query tree protocol for solving RFID tag collision problem

焦传海,王可人

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 3324 ) PDF (151 KB)( 437 )

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The technology of anti-collision is a key point in radio frequency identification (RFID) system. To avoid data collision, there are two approaches: ALOHA based algorithm and binary tree (BT) based algorithm. However, these cannot solve the collision problem completely, especially when the tag quantity is big and the tag ID is long. In this article, we present a multi-branch query tree (MBQT) protocol based on balanced incomplete block design (BIBD) code, and use 16-bit vectors derived from the BIBD as query prefix symbols of RFID reader. Compared with the conventional anti-collision algorithm, the theoretic analysis and simulation show that the proposed protocol improves the identification efficiency.

Security

Grid authentication from identity-based cryptography without random oracles

郑彦,王海艳,王汝传

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2595 ) PDF (192 KB)( 538 )

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As a critical component of grid security, secure and efficient grid authentication needs to be well addressed. However, the most widely accepted and applied grid authentication is based on public key infrastructure (PKI) and X.509 certificates, which make the system have low processing efficiency and poor anti-attack capability. To accommodate the challenge of grid authentication, this article aims at designing a secure and efficient method for grid authentication by employing identity-based cryptography (IBC). Motivated by a recently proposed secure and efficient identity-based encryption (IBE) scheme without random oracles, an identity-based signature (IBS) scheme is first proposed for the generation of private key during grid authentication. Based on the proposed IBS and the former IBE schemes, the structure of a novel grid authentication model is given, followed by a grid authentication protocol described in detail. According to the theoretical analysis of the model and the protocol, it can be argued that the new system has improved both the security and efficiency of the grid authentication when compared with the traditional PKI-based and some current IBC-based models.

Artificial Intelligence

Two schemes of perfect teleportation one-particle state by a three-particle general W state

查新未

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2428 ) PDF (96 KB)( 390 )

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In teleportation, it can be seen that the probability of success is determined by Alice’s measurement and quantum channel. If the Alice’s measurement is appropriate, the teleportation can be successfully realized with the maximal probability. In accordance with transformation operator, two schemes are proposed for teleportation of an unknown one-particle state via a general W state, through which the successful probability and the fidelity of both schemes reach 1. Furthermore, two optimal matches of orthogonal complete measurement bases are given for teleporting an unknown one-particle state.

Quantum secret sharing between multiparty and multiparty with entanglement swapping

林崧,高飞,秦素娟,温巧燕,朱甫臣

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2567 ) PDF (216 KB)( 383 )

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A quantum secret sharing (QSS) protocol between multiparty and multiparty is proposed, based on Greenberger–Horne– Zeilinger (GHZ) state. The protocol utilizes quantum Fourier transform and entanglement swapping to achieve a high intrinsic efficiency and source capacity. Then, the security of this protocol against some possible eavesdropping strategies has been analyzed. Furthermore, the presented protocol is generalized to the d-level case.

Anonymous authentication protocol for multi-services in wireless environments

姜楠,王健

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2967 ) PDF (158 KB)( 459 )

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To provide mutual authentication among users, wireless networks, and service providers in roaming wireless environments, this article presents an anonymous authentication and access control protocol. Bases on this protocol, entities of different trusted domains can mutually authenticate each other and preserve the anonymity of users. Hybrid cryptosystem, secret splitting, and hash chains are used in the protocol, which decrease computational loads and establish trusted relations for both entities. The proposed protocol has the least computation complexity compared with other protocols, whereas, the security has been significantly improved.

ID-based authentication scheme combined with identity-based encryption with fingerprint hashing

江为强,黄正全,杨义先,田捷,李亮

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2457 ) PDF (172 KB)( 529 )

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Current identity-based (ID) cryptosystem lacks the mechanisms of two-party authentication and user’s private key distribution. Some ID-based signcryption schemes and ID-based authenticated key agreement protocols have been presented, but they cannot solve the problem completely. A novel ID-based authentication scheme based on ID-based encryption (IBE) and fingerprint hashing method is proposed to solve the difficulties in the IBE scheme, which includes message receiver authenticating the sender, the trusted authority (TA) authenticating the users and transmitting the private key to them. Furthermore, the scheme extends the application of fingerprint authentication from terminal to network and protects against fingerprint data fabrication. The fingerprint authentication method consists of two factors. This method combines a token key, for example, the USB key, with the user’s fingerprint hash by mixing a pseudo-random number with the fingerprint feature. The security and experimental efficiency meet the requirements of practical applications.

Electromagnetic Compatibility

Shielding effectiveness of rectangular cavity made of a new shielding material and resonance suppression

汪柳平

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2845 ) PDF (260 KB)( 413 )

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New shielding material has become an alternative to traditional metal to shield boxes from electromagnetic interferences. This article introduces the theory of transmission line method to study the shield boxes made of a new sort of material, and then expands the fundamental formulas to deal with the cases of multiple holes and polarization with arbitrary angle. By means of genetic algorithms with the aid of a three dimensional simulation tool, the damping of electromagnetic resonances in enclosures is researched.
The computation indicates that under resonant frequency, electromagnetic resonance results in low, even negative shielding coefficient; whereas, for the same areas, shielding effectiveness of a single hole is worse than that of multiple holes. Shielding coefficient varies when polarization angle increases, and the coupled field through the rectangular aperture with the long side parallel to the thin wire is much weaker than that with the long side vertical to the thin wire. By using the metallic-loss dielectric layer of optimized calculation on the internal surface of the cavity, the best result of resonance suppression has been realized with the same thickness of coating. Finally, according to the calculation result, suggestions for shielding are proposed.

Voltage dependence property of parameters for human body discharge in air through a small metal rod

阮方鸣,高攸纲,FUJIWARA 0samu

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2875 ) PDF (391 KB)( 392 )

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Discharge parameters are measured and calculated in electrostatic discharge (ESD) from charged human body through a small moving handheld metal rod. Correlation study has been performed on discharge parameters with charge voltage as well as approach speed. At charge voltage 800 V, difference of discharge parameters caused by fast and slow approach speed of electrode is found to reach extreme values. To explore the reason for this special case, an analysis with a short-gap ESD model is carried out.

Artificial Intelligence

Analysis of S-SEED’s characteristics in optical switch

曹永盛,尹霄丽,忻向军,余重秀

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2120 ) PDF (256 KB)( 468 )

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This article introduces the basic structure of a symmetric self-electrooptic effect device (S-SEED), and applies the Kirchoff’s current law and a purely equivalent capacitive model, to analyze S-SEED’s switch characteristics. Linear approximation and N-segment approximation are utilized to obtain S-SEED’s voltage-time (V-T) and characteristics. Theoretical analysis is verified by simulations, and the results demonstrate that the precision of S-SEED’s switch time can satisfy the requirement in applications with linear approximation. Moreover, the simulations compare S-SEED’s switch characteristics with different input powers and input contrast ratios, which reveal that increasing input contrast ratio is an effective way to improve S-SEED’s switch characteristics.

QoS multicast routing scheme using QGA in IP/DWDM networks

邢焕来,柏琳,纪越峰

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 3080 ) PDF (232 KB)( 501 )

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This article studies multi-constraints least-cost multicast routing problem in internet protocol over dense wavelength division multiplexing (IP/DWDM) networks. To address this problem, an individual-difference-based quantum genetic algorithm (IDQGA) is proposed. This algorithm considers individual differences among chromosomes by introducing an adaptive rotation angle step determination scheme and a grouping-based quantum mutation operation. Simulations are conducted over network topologies. The results indicate that compared with other heuristic algorithms, IDQGA has better optimal performance on solving quality of service (QoS) multicast routing problem in IP/DWDM networks and is characterized by strong robustness, high success ratio and excellent capability on global searching.

The research of DPA attacks against AES implementations

韩煜,邹雪城,刘政林,陈毅成

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2589 ) PDF (311 KB)( 514 )

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This article examines vulnerabilities to power analysis attacks between software and hardware implementations of cryptographic algorithms. Representative platforms including an Atmel 89S8252 8-bit processor and a 0.25 μm 1.8 v standard cell circuit are proposed to implement the advance encryption standard (AES). A simulation-based experimental environment is built to acquire power data, and single-bit differential power analysis (DPA), and multi-bit DPA and correlation power analysis (CPA) attacks are conducted on two implementations respectively. The experimental results show that the hardware implementation has less data-dependent power leakages to resist power attacks. Furthermore, an improved DPA approach is proposed. It adopts hamming distance of intermediate results as power model and arranges plaintext inputs to differentiate power traces to the maximal probability. Compared with the original power attacks, our improved DPA performs a successful attack on AES hardware implementations with acceptable power measurements and fewer computations.

UWB Wireless Communications and CMOS RF IC Design

Design of a fully differential CMOS LNA for 3.1–10.6 GHz UWB communication systems

张鸿,陈贵灿

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 3702 ) PDF (268 KB)( 640 )

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A fully differential complementary metal oxide semiconductor (CMOS) low noise amplifier (LNA) for 3.1–10.6 GHz ultra-wideband (UWB) communication systems is presented. The LNA adopts capacitive cross-coupling common-gate (CG) topology to achieve wideband input matching and low noise figure (NF). Inductive series-peaking is used for the LNA to obtain broadband flat gain in the whole 3.1–10.6 GHz band. Designed in 0.18 m CMOS technology, the LNA achieves an NF of 3.1–4.7 dB, an S11 of less than –10 dB, an S21 of 10.3 dB with 0.4 dB fluctuation, and an input 3rd interception point (IIP3) of –5.1 dBm, while the current consumption is only 4.8 mA from a 1.8 V power supply. The chip area of the LNA is 10.94 mm2.

P2P

Identifying file-sharing P2P traffic based on traffic characteristics

成卫青,龚俭,丁伟

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2204 ) PDF (301 KB)( 470 )

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This article focuses on identifying file-sharing peer-to-peer (P2P) (such as BitTorrent (BT)) traffic at the borders of a stub network. By analyzing protocols and traffic of applications, it is found that file-sharing P2P traffic of a single user differs greatly from traditional and other P2P (such as QQ) applications’ traffic in the distribution of involved remote hosts and remote ports. Therefore, a method based on discreteness of remote hosts (RHD) and discreteness of remote ports (RPD) is proposed to identify BT-like traffic. This method only relies on flow information of each user host in a stub network, and no packet payload needs to be monitored. At intervals, instant RHD for concurrent transmission control protocol and user datagram protocol flows for each host are calculated respectively through grouping flows by the stub network that the remote host of each flow belongs to. On given conditions, instant RPD are calculated through grouping flows by the remote port to amend instant RHD. Whether a host has been using a BT-like application or not can be deduced from instant RHD or average RHD for a period of time. The proposed method based on traffic characteristics is more suitable for identifying protean file-sharing P2P traffic than content-based methods. Experimental results show that this method is effective with high accuracy.

Intelligent Computing

Research on cultural algorithm for solving routing problem of mobile agent

马俊,ZHANG Jian-pei, YANG Jing, CHENG Li-li

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 2123 ) PDF (175 KB)( 434 )

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The key idea behind cultural algorithm is to explicitly acquire problem-solving knowledge from the evolving population and in return apply that knowledge to guide the search. In this article, cultural algorithm-simulated annealing is proposed to solve the routing problem of mobile agent. The optimal individual is accepted to improve the belief space’s evolution of cultural algorithms by simulated annealing. The step size in search is used as situational knowledge to guide the search of optimal solution in the population space. Because of this feature, the search time is reduced. Experimental results show that the algorithm proposed in this article can ensure the quality of optimal solutions, and also has better convergence speed. The operation efficiency of the system is considerably improved.

Computer Application and Information System

An architecture of knowledge management system based on agent and ontology

付瑞雪,岳欣,宋明,忻展红

中国邮电高校学报(英文), 2008, 15 (4). doi：

摘要 ( 3269 ) PDF (201 KB)( 566 )

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To solve the problems in knowledge management system (KMS), such as information sharing, the ability to extend and re-engineer, and the reusable ability of legacy systems in distributed and heterogeneous environments. This article presents a method based on agent and ontology of designing KMS. This method consists of two agencies. One is knowledge agency with three agents supporting knowledge management process. The other is application agency with three agents supporting knowledge application. In this method, ontology is used to represent the knowledge in knowledge base and the content in the message exchanged among agents. To demonstrate the advantages of this method, experiments have been carried out and the results imply that this method is efficient and effective for small and medium-size enterprises to design KMS.