本期目录

2009年 16卷 5期 刊出日期：2009-10-30



Wireless

Diversity order of decode-and-forward MIMO relaying
with transmit antenna selection

曹磊;杨鸿文;张欣;杨大成

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60260-5

摘要 ( 2348 ) PDF (204 KB)( 453 )

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This article analyzes the diversity order of several proposed schemes, where the transmit antenna selection (TAS) strategies are combined with low-complexity decode-and-forward (DF) protocols in the multiple-input multiple-output (MIMO) relaying scenario. Although antenna selection is a suboptimal form of beamforming, it enjoys the advantages of tractable optimization and low feedback overhead. Specifically, this article proposes schemes that combine TAS strategies with fixed decode-and-forward (FDF) and selection decode-and-forward (SDF) protocols. Following that, the asymptotic expressions of outage probabilities are derived and the diversity order of the proposed schemes analyzed. These kinds of combination of transmit antenna selection strategies and low-complexity decode-and-forward protocols can achieve partial diversity order in the MIMO relaying scenario. The numerical simulations verify the analysis.

Cooperative HARQ protocol and diversity analysis of systems with multiple incremental relays

范斌,王文博,林懿诚,郑侃

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60261-7

摘要 ( 2322 ) PDF (345 KB)( 382 )

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Wireless networks contain an inherent distributed spatial diversity that can be exploited by relays. Relay networks can take advantage of the broadcast-oriented nature of wireless transmission, but require more radio resource to transmit data for their multi-hop traits. Fortunately, incremental relaying technique, which can choose direct or multi-hop transmission adaptively, can efficiently utilize resource. In this article, the incremental transmission with amplify-and-forward (AF) relays is focused on. A practical hybrid-automatic retransmission request (HARQ) protocol is designed, and the related optimal relay selection strategy is proposed. To analyze the cooperative diversity of system with the proposed protocol, the capacity lower bound is deduced. Simulation and analytical results indicate that by adopting the optimal relay selection strategy, the system with the proposed HARQ protocol can achieve an order of cooperative diversity that equals the aggregated number of the relay and source nodes.

Performance analysis of ARQ schemes with code combining over Nakagami-m fading channel

徐文波,牛凯,林家儒,贺志强

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60262-9

摘要 ( 2170 ) PDF (266 KB)( 429 )

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This article investigates the performance of hybrid automatic repeat request (HARQ) with code combining over the ideally interleaved Nakagami-m fading channel. Two retransmission protocols with coherent equal gain code combining are adopted, where the entire frame and several selected portions of the frame are repeated in protocols I and II, respectively. Protocol II could be viewed as a generalization of the recently proposed reliability-based HARQ. To facilitate performance analysis, an approximation of the product of two independent Nakagami-m distributed random variables is first developed. Then the approximate analysis is utilized to obtain exact frame error probability (FEP) for protocol I, and the upper bound of the FEP for protocol II. Furthermore, the throughput performance of both two protocols is presented. Simulation results show the reliability of the theoretical analysis, where protocol II outperforms protocol I in the throughput performance due to the reduced amount of transmitted information.

Performance evaluation of channel inversion precoding for
downlink multi-user MIMO system

陈智勇，王文博，彭木根, 李韧

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60263-0

摘要 ( 3470 ) PDF (227 KB)( 409 )

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In downlink multi-user multi-input multi-output (MU-MIMO) system, not every user (user equipment (UE)) can calculate accurately signal to interference and noise ratio (SINR) without prior knowledge of the other users’ precoding vector. To solve this problem, this article proposes a channel inversion precoding scheme by using the lower bound of SINR and zero-forcing (ZF) algorithm. However, the SINR mismatch between lower bound SINR and actual SINR causes the inaccurateness of adaptive modulation and coding (AMC). As a result, it causes degradation in performance. Simulation results show that channel inversion precoding provides lower throughput than that of single user multi-input multi-output (SU-MIMO) at high signal-to-noise ratio (SNR) (>14 dB), due to the SINR mismatch, although the sum-rate of channel inversion precoding is higher than that of SU-MIMO at full SNR regime.

Resource allocation based on genetic algorithm for multi-hop
OFDM system with non-regenerative relaying

时洁,许文俊,吴伟陵

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60264-2

摘要 ( 2438 ) PDF (320 KB)( 421 )

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This article investigates resource allocation in multi-hop orthogonal frequency division multiplexing (OFDM) system with amplifying-and-forwarding relaying to maximize the end-to-end capacity. Most existing methods for multi-hop system focus on power allocation or subcarrier selection separately, but joint resource allocation is rarely considered due to the absence of effective interaction schemes. In this work, a novel joint resource allocation methodology is proposed based on Partheno genetic algorithm (PGA), which produces excellent subcarrier allocation set (referred to as individual in PGA) with higher capacity by evolution operator generation by generation. In addition, an adaptive power allocation is also designed to evaluate the fitness of PGA and further enhance the system capacity. Both theoretical analysis and simulated results show the effectiveness of the proposed joint strategy. It outperforms the traditional method by as much as 40% capacity improvement for 3-hop relaying system when system power is high, and obtains much more capacity enhancement percent under conditions of low system power.

Low complexity resource allocation and scheduling algorithms for downlink SDMA systems

孙锴,王莹,张平

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60265-4

摘要 ( 2294 ) PDF (277 KB)( 375 )

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The downlink zero-forcing beamforming strategy in the case of random packet arrivals is investigated. Under this setting, the relevant fairness criterion is the stabilization of all buffer queues which guarantees a bounded average delay for all users. It has been shown that allocating resources to maximize a queue-length-weighted sum of the rates is a stabilizing policy. However, the high complexity of user selection and the feasible rates determination for optimal scheme may prevent the real-time scheduling operation. Two low complexity algorithms are provided taking the channel state, queue state and orthogonality into account. In particular, the authors pick the first user with the largest product between channel gain and queuing length, and select the remaining users to construct candidate user set based on the greedy user selection method or channel orthogonal user selection method. Then, the power and rate allocation for the selected users are implemented based on the modified water-filling method. The complexity of the proposed algorithms is analyzed. The average delay and average throughput are studied in homogeneous scenarios and heterogeneous scenarios, respectively. Simulation results show that the proposed algorithms can take full advantage of the multi-user diversity gain and provide average delay (or throughput) and fairness improvement compared with channel-aware-only schemes.

Optimization of listening time of S-MAC for wireless sensor networks

李成,王葵如,张锦龙,赵德馨， LI Wang

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60266-6

摘要 ( 2123 ) PDF (225 KB)( 437 )

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In wireless sensor networks, sensor nodes are usually battery-operated computing and sensing devices, hence operations are limited by the initially equipped batteries, which are hard to be recharged or replaced. In this sense, saving energy consumption becomes significant. As most energy waste is from the always-on wireless interface, S-MAC is suggested to reduce energy consumption by introducing periodic listen/sleep scheme. However, when designing the listening time, S-MAC fails to consider the traffic distribution factor. In this article, an optimization for this scheme is proposed based on the distribution model. Evaluations show that the optimized S-MAC achieves considerable improvement in energy and latency.

Outage probability of opportunistic decode-and-forward
relaying over Nakagami-m fading channels

啜钢，ZHANG Bao-zhi, LIU Xing-mei, GAO Li

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60267-8

摘要 ( 2318 ) PDF (238 KB)( 413 )

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In this article, the outage probability behavior of a relay network over Nakagami-m fading channels is analyzed. Both reactive and proactive opportunistic decode-and-forward (DAF) strategies are considered. The closed-form solutions to the outage probabilities on both opportunistic DAF strategies are derived. Simulation results confirm the presented mathematical analysis.

Networks

Selective parsing to enhance SIP performance

曹予飞,廖建新,戚琦,朱晓民

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60268-X

摘要 ( 2989 ) PDF (211 KB)( 203 )

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The session initiation protocol (SIP) is used as the signaling protocol in the IP multimedia subsystem (IMS) and the signaling is becoming computing intensive comparing to the current telecommunication network. The SIP is a text-based protocol with characteristics of unordered and verbose headers, variable-size message, and case-insensitive keyword. It imposes challenges for an efficient message processing. The property of SIP elements being able to process SIP messages quickly is critical for the performance of IMS networks. This article investigates the performance of SIP message processed in SIP servers, mainly focusing on improving message parsing by introducing a method named selective parsing for SIP message (SP4SIP). By modeling and analyzing a SIP server with a tandem Jackson network, it is concluded that parsing messages is the bottleneck of a SIP server performance, i.e., it is the most processing intensive activity in the system. To validate the approach, it has been implemented in a high-performance SIP server in the authors’ lab. The results show that selective parsing for SIP message can indeed reduce processing time.

Cooperative localization for next-generation converged
networks with closed-form solution

张一衡,崔琪楣,张平,陶小峰

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60269-1

摘要 ( 2158 ) PDF (403 KB)( 349 )

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In this article, a novel cooperative wireless localization scheme based on information fusion is proposed. The scheme combines large-scale arrival time and small-scale distance measurements obtained from the next-generation converged networks. The maximum likelihood (ML) estimate of the terminal’s position is derived with closed-form solution, and the Cramér-Rao lower bound (CRLB) of the estimate error is investigated. Both theoretical analysis and simulation results verify that the proposed localization scheme can significantly enhance the location precision. Moreover, the mean square error of position estimate approximates the CRLB when the number of reference stations increases, which indicates that the proposed ML estimator is asymptotically efficient.

Reliability evaluation of wireless sensor networks using
an enhanced OBDD algorithm

肖宇峰,陈山枝,李昕,李玉宏

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60270-8

摘要 ( 2370 ) PDF (362 KB)( 527 )

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An enhanced ordered binary decision diagram (EOBDD) algorithm is proposed to evaluate the reliability of wireless sensor networks (WSNs), based on the considerations of the common cause failure (CCF) and a large number of nodes in WSNs. The EOBDD algorithm analyzes the common cause event (CCE) and the network structure when CCE takes place according to the stochastic graph and the CCF model of WSNs. After constructing the ordered binary decision diagram (OBDD) of the original network with node expansion, it uses a set of OBDD variables (SOV) to guide reliability computations along this OBDD. The two steps about OBDD can decrease the cost of OBDD constructions and storage. Furthermore, the efficient OBDD structure and Hash tables can greatly decrease redundant computations of isomorphs. The experiment results show that the EOBDD can be used to evaluate the reliability of WSN efficiently.

Quantitative and qualitative research on service quality
evaluation system in NGN

刘露,周文安,宋俊德

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60271-X

摘要 ( 2133 ) PDF (205 KB)( 387 )

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With the development of next generation network (NGN), reasonable service quality evaluation is essential in network management. Based on NGN service characteristics, this article presents a comprehensive service quality evaluation system from two perspectives: quantitative and qualitative. From the quantitative point of view, this article brings forward the normalized service level achievement function (NSLA function) at technical layer. Also, with mean opinion score (MOS) mode, it proposes customer satisfaction assessment methods at customer perception layer. From the qualitative perspective, a hierarchical model is established, which forms mapping relations from the upper customer perception to the lower service quality parameters, and then the influence of different service parameters on customer satisfaction degree can be denoted by the fuzzy analysis hierarchy process (FAHP) algorithm. Quantitative and qualitative evaluations together form a comprehensive solution which is universal, customer-oriented and flexible. Demonstrated by the representative voice service, the proposed system is proved reliable and applicable to service evaluation in NGN.

Performance analysis of rate-adaptive cooperative MAC based
on wireless local area networks

张杨,徐洪锟,常永宇,杨大成,王亚峰

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60272-1

摘要 ( 2117 ) PDF (373 KB)( 399 )

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Bi-dimensional Markov chain model based on cooperative medium access control (MAC) of wireless local area networks (WLAN) is considered to reflect system performance accurately. Two basic factors that affect the analysis results are station retry limits and non-saturated transmit probability. A uniform solution considering both factors is proposed. To prove the theoretical analysis, a cooperative MAC (CoopMAC) topology is established and the simulation model is enhanced by changing the cooperative table to the nodes’ memory with more information added. Meanwhile, the three-way handshake scheme is modified and a handshake threshold is set based on the packet size. Simulation results show the performance analytical model is accurate, and the rate-adaptive cooperative MAC protocol significantly improves the network performance in terms of non-saturated system throughput and delay.

Others

S-Mesh: a Mesh-based on-chip network with
separation of control and transmission

刘浩; 邹雪城; 蔡梦;吉立新;张科峰

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60273-3

摘要 ( 2178 ) PDF (291 KB)( 356 )

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The current network-on-chip (NoC) topology cannot pre¬dict subsequent switch node status promptly. Switch nodes have to perform various functions such as routing decision, data forwarding, packet buffering, congestion control and properties of an NoC system. Therefore, these make switch architecture far more complex. This article puts forward a separating on-chip network architecture based on Mesh (S-Mesh). S-Mesh is an on-chip network that separates routing decision flow from the switches. It consists of two types of networks: datapath network (DN) and control network (CN). The CN establishes data paths for data transferring in DN. Meanwhile, the CN also transfers instructions between different resources. This property makes switch architecture simple, and eliminates conflicts in network interface units between the resource and switch. Compared with 2D-Mesh, Torus Mesh, Fat-tree and Butterfly, the average packet latency in S-Mesh is the shortest when the packet length is more than 53 B. Compared with 2D-Mesh, the areas savings of S-Mesh is about 3%–7%, and the power dissipation is decreased by approximate 2%.

Key-frame reference selection for non-feedback video communication

彭强,张蕾,YANG Tian-wu,Jim X. Chen,Zhu Ce

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60274-5

摘要 ( 2085 ) PDF (554 KB)( 204 )

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This article addresses the problem of reference picture optimization in video communication over error prone networks. A novel estimation model for transmission distortion is proposed. This model is capable of recursively estimating the overall end-to-end distortion caused by quantization, error propagation, and error concealment. Simulation results show that this model can accurately estimate channel distortion. Then, based on the distortion estimation model, a new non-feedback key-frame reference picture selection (KRPS) algorithm is developed. The optimum reference picture minimizes the transmission distortion under the rate-distortion optimization framework. Extensive experiment results demonstrate that the proposed KRPS algorithm substantially achieves more peak signal to noise ratio (PSNR) gain over traditional prediction, especially in low bit-rate transmission.

Construction of LDPC codes over GF(q) with
modified progressive edge growth

陈昕,门爱东,杨波,全子一

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60275-7

摘要 ( 2272 ) PDF (135 KB)( 379 )

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A parity check matrix construction method for constructing a low-density parity-check (LDPC) codes over GF(q) (q>2) based on the modified progressive edge growth (PEG) algorithm is introduced. First, the nonzero locations of the parity check matrix are selected using the PEG algorithm. Then the nonzero elements are defined by avoiding the definition of subcode. A proof is given to show the good minimum distance property of constructed GF(q)-LDPC codes. Simulations are also presented to illustrate the good error performance of the designed codes.

Structure splitting framework for data-layout optimization

付雄;王汝传

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60276-9

摘要 ( 2268 ) PDF (323 KB)( 370 )

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To improve data cache performance, optimizing program data layout by data reorganization has become an important method of decreasing the impact of increasing gap of speed between processor and memory. In this article, a structure splitting framework with an analysis model named structure field relation graph (SFRG) is presented to optimize program data layout. The SFRG can be used to quantify relationship between fields. It helps to find an optimal layout for structure as well as the optimal program data layout. And the data cache performance is improved through SFRG-based structure splitting. Experiments show that this framework is effective in optimizing program data layout and improving the performance of data cache and whole program.

Fair e-payment protocol based on blind signature

王建辉,LIU Jing-wei, LI Xiao-hui, KOU Wei-dong

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60277-0

摘要 ( 2432 ) PDF (258 KB)( 582 )

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Electronic transaction through e-payment protocol will grow tremendous in the coming years. In this article, by conversely using blind signature, the authors propose a fair electronic payment scheme for electronic commerce, which can ensure two participants’ right simultaneously in electronic transaction process. This scheme is different from other existing schemes and it does not require strong trust relation between customer and merchant. In the scheme, a semi-trusted third party (S-TTP) is involved to provide a fair commerce environment. The S-TTP takes part in the protocol on-line and no secure information about the business is leaked. Moreover, the participants do not need to register to S-TTP. This scheme does not require intervention of a third party in case of dispute, if one user cheats or simply crashes.

Direct computation of multiconductor transmission line
capacitance and charge distribution

徐军,吕英华, ZHANG Li-kun

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60278-2

摘要 ( 2032 ) PDF (382 KB)( 348 )

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The per-unit-length capacitance parameter of multiconductor transmission line (MTL) is commonly extracted with indirect matrix transform method, which is complex and time-consuming. To solve the problem, an improved method to directly compute the MTL capacitance is proposed, which can be applied in the transmission line structure with arbitrary shaped cross-section and arbitrary separate distance. This method imports voltage conversions and matrix operations to simplify the complexity, improves computational efficiency by about 600% with results as accurate as previous method. The novel method presents a clear charge distribution map of MTL, whereas precious method will experience a tortuous process to get charge distribution.

Research on user-aware QoS based Web services composition

刘枫,LEI Zhen-ming

中国邮电高校学报(英文), 2009, 16 (5). doi： 10.1016/S1005-8885(08)60279-4

摘要 ( 2432 ) PDF (265 KB)( 469 )

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To improve user experience of composite Web services, a user-aware quality of service (QoS) based Web services composition model is proposed. Under such model, a Web services selection method based on quantum genetic algorithm is proposed. This algorithm uses quantum bit encoding, dynamic step-length quantum gate angle adjustment, neighborhood service search and dynamic punishment strategy to expand search scope and speed up convergence. Simulation experiment shows that this algorithm is more efficient than other existing algorithms in Web services selection.