本期目录

2010年 17卷 3期 刊出日期：2010-06-30



Wireless

Complexity Study of Sphere Decoding in Multi-Antenna Systems

钱荣荣 漆渊 彭涛 王文博

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60459-3

摘要 ( 3870 ) PDF (0 KB)( 493 )

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In this article a bridge between the expected complexity and performance of sphere decoding (SD) is built. The expected complexity of SD for infinite lattices is then investigated, which naturally is the upper-bound of those for all the finite lattices if given by the same channel matrix and signal noise ratio (SNR). Such expected complexity is an important characterization of SD in multi-antenna systems, because no matter what modulation scheme is used in practice (generally it has finite constellation size) this upper-bound holds. Above bridge also leads to a new method of determining the radius for SD. The numerical results show both the real value and upper-bound of average searched number of candidates in SD for 16-QAM modulated system using the proposed sphere radius determining method. Most important of all new understandings of expected complexity of SD are given based on above mentioned theoretic analysis and numerical results.

 Game-Theoretic Spectrum Sharing for Cognitive Radio Based on the Expectation of Primary Users

马良 朱琦

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60472-6

摘要 ( 3400 ) PDF (0 KB)( 460 )

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Cognitive radio is a new intelligent wireless communication technique for remedying the shortage of spectrum resource in recent years. Secondary users have to pay when they share available spectrum with primary users while price is an important factor in the spectrum allocation. Based on the game theory, an improved pricing function is proposed by considering the expectation of primary users. In this article, expectation represents the positivity of sharing spectrum with primary users. By introducing the positivity, price not only becomes different for different secondary users, but also can be adjusted according to the positivity. It is proved that the Nash Equilibrium of the new utility function exists. The simulation results show that spectrum sharing can not only be determined by the channel quality of secondary users, but also can be adapted according to the expectation of primary users. Besides, the proposed algorithm improves the fairness of sharing.

Parallel Interference Cancellation for Carrier Frequency Offset in OFDM Assisted with Recursive Least Squares algorithm

关庆阳, ZHAO Hong-lin, GUO Qing

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60473-8

摘要 ( 3711 ) PDF (0 KB)( 468 )

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Parallel interference cancellation (PIC) assisted with recursive least squares (RLS) algorithm is proposed to cancel the interference due to the carrier frequency offset (CFO) in orthogonal frequency division multiplexing (OFDM) system. The proposed algorithm is composed of two stages, which are RLS scheme and PIC scheme. RLS scheme is selected to compensate the frequency offset in the time domain in the first stage, and the interference induced by residual frequency offset is canceled by the PIC scheme in the frequency domain in the second stage. The result of bit error rate (BER) shows that its performance is robust for cancellation as comparison criteria, even though the frequency offset is 0.45. The 16QAM constellation is also simulated to observe the improvements from the proposed suppression schemes.

CMOS Ring VCO for UHF RFID Readers

孙玲 唐路 Jiang Wei-ping Xia jun

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60474-X

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A complementary metal oxide semiconductor (CMOS) voltage controlled ring oscillator for ultra high frequency (UHF) radio frequency identification (RFID) readers has been realized and characterized. Fabricated in charter 0.35 ?m CMOS process, the total chip size is 0.47×0.67 mm2. While excluding the pads, the core area is only 0.15×0.2 mm2. At a supply voltage of 3.3 V, the measured power consumption is 66 mW including the output buffer for 50 ? testing load. This proposed voltage-controlled ring oscillator exhibits a low phase noise of 116 dBc/Hz at 10 MHz offset from the center frequency of 922.5 MHz and a lower tuning gain through the use of coarse/fine frequency control.

Multicast resource allocation with min-rate requirements in OFDM systems

许文俊 贺志强 牛凯 林家儒 吴伟陵

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60475-1

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This article addresses the multicast resource allocation problem with min-rate requirement constraints in orthogonal frequency division multiplexing (OFDM) systems. Due to the prohibitively high complexity for nonlinear and combinatorial optimization, the original problem is relaxed and reformulated to form a standard optimization problem. By theoretical derivation according to the Karush-Kuhn-Tucker (KKT) conditions, two propositions are presented as the necessary criteria for optimality. Furthermore, a two-step resource allocation scheme, including subcarrier assignment and power allocation, is proposed on a basis of the propositions for practical implementation. With the min-rate based multicast group order, subcarriers are assigned in a greedy fashion to maximize the capacity. When subcarrier assignment is determined, the proposed power allocation can achieve the optimal performance for the min-rate constrained capacity maximization with an acceptable complexity. Simulation results indicate that the proposed scheme approximates to optimal resource allocation obtained by exhaustive search with a negligible capacity gap, and considerably outperforms equal power distribution. Meanwhile, multicast is remarkably beneficial to resource utilization in OFDM systems.

Non-cooperative power control game for adaptive modulation and coding

高鹏 程楠 方媛 梁双春 孟德香 涂国防

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60467-2

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Adaptive modulation and coding (AMC) provides the flexibility to match modulation and coding scheme (MCS) to signal to interference plus noise ratio (SINR) of users. To reduce the transmission power and maintain the transmission quality, power control is normally combined with AMC. While the target SINR of power control is fixed，therefore non-cooperative power control game for AMC (NPGA) algorithm was proposed to adapt to the dynamic target SINR changes according to MCS. In NPGA, we formulate system transmission efficiency via utility, where the utility function is constructed based on the modulation and coding efficiency with non-cooperative game theory. It is demonstrated theoretically that NPGA can satisfy the conditions of the supermodular games, and its solution is optimal. The simulation results show that NPGA can improve system transmission efficiency and signal quality with low transmission power, and the convergence performance of NPGA is more fast-effectiveness compared with geometric programming algorithms.

Spatial characteristics and capacity investigation of indoor hotspot channel based on wideband MIMO measurement at 4.9 GHz

聂欣 张建华 黄晨 刘泽民 张平

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60466-0

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In this article, results obtained from wideband multiple-input multiple-output channel measurements at 4.9 GHz are presented. Measurements were performed in an indoor hotspot scenario with both line-of-sight and non-line-of-sight propagation conditions. Vertical polarized uniform linear arrays (ULAs) with different antenna spacing and orientation were utilized for investigating the impact of antenna configurations on the system performance. Based on measured channel impulse responses, the spatial correlation of ULA is analyzed and compared with the theoretical values calculated from the power azimuth spectrum. Following that, the eigenvalue statistics and capacity with respect to antenna spacing and orientation are given and compared. The diversity-multiplexing tradeoff (DMT) of measured channels at operational signal-to-noise ratio (SNR) is also presented. The reason why the DMT of measured channels is much lower than that of i.i.d. Rayleigh channels is specified.

Group-blind multi-user detection under multi-path channel

王东昱 Liu Wen-kai 杨俊 Yang Da-cheng

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60460-X

摘要 ( 3531 ) PDF (0 KB)( 461 )

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This article proposes an improved generalized side-lobe canceller (GSC) receiver structure based on a new group constraint, which is suitable to eliminate multiple-access interference (MAI), inter-symbol interference (ISI) in direct-sequence code-division multiple access (DS/CDMA) downlink multi-user system. The new group constraint is deduced to construct the group-blind adaptive multi-user detector. The analysis indicates that the improved GSC under the new constraint not only retains the property of suppressing ISI and canceling MAI, but also can extract useful information from the succeeding bit for the desired user. The simulations show that the improved GSC filter can cancel the MAI efficiently whether the wireless channel length is short or long, and achieve better performance than other compared filters.

Digital modulation recognition based on instantaneous information

Hu Yong-qiang Liu Juan 谭晓衡

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60471-4

摘要 ( 3219 ) PDF (0 KB)( 466 )

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A new digital modulation recognition algorithm based on the instantaneous information is proposed to improve the recognition success rate in the low signal noise ratio (SNR). First denoising of the instantaneous information is optimized by wavelet filter, which can improve the recognition ability at low SNR. Besides the existing 3 key feature parameters, 3 new key feature parameters are proposed to be used as the decision criteria for identifying different types of digital modulation, which simplifies the recognition process and improves the recognition ability at low SNR. The simulations demonstrate that all modulation types of interest have been classified with success rate of no lower than 99 % when SNR is 10dB. Even if the SNR is lower than 5 dB, the success rate is over 95.4 % for most of the modulation types.

Design of an L1 band low noise single-chip GPS receiver in 0.18 um CMOS technology

陈莹梅 李智群 Wang Zhi-gong 景永康 章丽

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60463-5

摘要 ( 2983 ) PDF (0 KB)( 426 )

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This article presents an L1 band low noise integrated global positioning system (GPS) receiver chip using 0.18 CMOS technology. Dual-conversion with a low-IF architecture was used for this GPS receiver. The receiver is composed of low noise amplifier (LNA), down-conversion mixers, band pass filter, received signal strength indicator, variable gain amplifier, programmable gain amplifier, ADC, PLL frequency synthesizer and other key blocks. The receiver achieves a maximum gain of 105 dB and noise figure less than 6 dB. The variable gain amplifier (VGA) and programmable gain amplifier (PGA) provide gain control dynamic range over 50 dB. The receiver consumes less than 160 mW from a 1.8 V supply while occupying a 2.9 mm2 chip area including the ESD I/O pads.

Network

HPSIN: a new hybrid P2P spatial indexing network

吴家皋 江南 邹志强 胡斌 黄琳 冯佳丽

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60468-4

摘要 ( 3721 ) PDF (0 KB)( 445 )

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Geographic information system (GIS) is increasingly managing very large sets of data, hence a centralized data index may not always provide the most scalable solution. Recently, the peer to peer (P2P) networks have become very popular for sharing information in a totally decentralized manner. In this paper, a new hybrid P2P spatial indexing network (HPSIN) is proposed, which combines distributed quad-tree with distributed Hash table (DHT) based Chord network to maintain both query efficiency and system load balance. In addition, a simple theoretical model based on opened queueing network for HPSIN is established. Assuming each peer as M/M/1 queueing processor in the model, fundamental characteristics of the system is captured, and expression of average query delay is obtained in close form. The theoretical analysis and numerical computing results show that there exists an optimum point of tradeoff between efficiency and load balance. By setting a proper value of start index level ls for different network scale and query rate, HPSIN will achieve the minimum overall query delay, therefore, can adapt to different P2P application environments.

Low-cost binding update scheme based on pointer forwarding in HMIPv6 network

刘银龙 曾志民 夏海轮 Zhang Tian-kui Hao Xiao-yan

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60465-9

摘要 ( 3498 ) PDF (0 KB)( 468 )

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By introducing a mobility anchor point (MAP), hierarchical mobile IPv6 (HMIPv6) reduces the binding update signaling cost associated with mobile IPv6, but there still exist deficiencies. For instance, a mobile node (MN) needs to orderly accomplish two binding updates with the MAP and home agent (HA) when the MN performs inter-MAP mobility. This results in a high signaling cost, thus affecting network performance. To reduce the inter-MAP binding update cost of idle MN in HMIPv6, an optimization scheme based on pointer forwarding with a threshold is proposed. The scheme can reduces the binding update cost of idle MN by using the binding update between MAP to replace several home binding updates. The signaling cost difference is derived by analyzing the cost of the basic scheme and the optimization scheme between two successive sessions. Simulation results show that, the optimization scheme can reduce the binding update signaling cost and improve the network performance as long as a suitable threshold is chosen. The discussions on the sensitivity of tele-parameters are also given.

Valiant load-balancing and regionalized routing scheme

杨帆 王振凯 陈建亚 刘韵洁

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60464-7

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Valiant load-balancing (VLB) routing scheme has drawbacks of logical full mesh, intermediate nodes (networks) and single application of topology. To address these, the authors propose a novel routing scheme called regionalized VLB (R-VLB). Based on ideas of VLB and regionalizing, R-VLB divides the nodes of backbone network into several regions whose topological structure is logical full mesh, and combines shortest-path routing scheme and VLB routing scheme. R-VLB also achieves logical local interconnection, non-central nodes (networks) and a wide range of application of topology. The relevant theoretical analysis and simulation results show that R-VLB achieve good throughput and failure performance close to that of VLB, and it even has better delay performance. R-VLB provides an idea for the application of VLB routing scheme.

User-perceived e-mail service QoS parameters and measurement

李永智 刘枫 雷振明 Chen Ling

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60469-6

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A group of quality of service (QoS) parameters of electronic mail (e-mail) traffic are proposed from users’ perspective. These parameters cover three fields: delay, throughput and usability. Concept and algorithm of each parameter are presented and its effect on user perceptions is described. In order to evaluate the effectiveness of these parameters, an active measurement system is implemented. Measured results show that the group of QoS parameters we proposed can be used to get a comprehensive view of user-perceived e-mail service QoS.

Others

Variable-rate convolutional network coding

马松雅 Chen Xiu-bo 罗明星 杨义先

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60462-3

摘要 ( 3675 ) PDF (0 KB)( 449 )

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Four types of variable-rate convolutional network codes are investigated over a single-source finite cyclic network. It is found that variable-rate generic, dispersion and broadcast can be implemented on the same network without changing the local encoding kernels of the non-source nodes. The efficient implementation has the advantage that each non-source node only needs to store one copy of the local encoding kernel within a session. However, it is also shown by an example that variable-rate multicast may not always be implemented under the above condition.

Active-fault-alarm based pre-restoration mechanism in MPLS-TP optical network

白晖峰 陆月明 纪越峰

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60478-7

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The newly developed multi-protocol label switching transport profile (MPLS-TP) fails to actively alarm the fault in advance when conducting restoration in network, or to avoid the false-alarm when equipped with the active-fault-alarm (AFA) to support carrier-grade reliability. In order to solve this problem, a new AFA based pre-restoration mechanism (AFABPRM) is proposed for MPLS-TP controlled optical network, along with the three levels quality-of-service (QoS) based shortest path first rerouting algorithm (TQ-SPF) in this article. The AFABPRM takes full advantage of the AFA technologies, and can solve the false-alarm problem. Analytical and experimental results suggest the better performances of the new mechanism when compared restoration mechanism with or without AFA function, and show that the AFABPRM can solve the false-alarm problem efficiently.

Blind image deconvolution for single motion-blurred image

孙韶杰 吴琼 李国辉

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60470-2

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Motion blur due to camera shake during exposure is one of the most common reasons of image degradation, which usually reduces the quality of photographs seriously. Based on the statistical properties of the natural image’s gradient and the blur kernel, a blind deconvolution algorithm is proposed to restore the motion-blurred image caused by camera shake, adopting the variational Bayesian estimation theory. In addition, the ring effect is one problem that is not avoided in the process of image deconvolution, and usually makes the visual effect of the restored image badly. So a dering method is put forward based on the sub-region detection and fuzzy filter. Tested on the real blurred photographs, the experimental results show that the proposed algorithm of blind image deconvolution can remove the camera-shake motion blur from the degraded image effectively, and can eliminate the ring effect better, while preserve the edges and details of the image well.

Search recommendation model based on user search behavior and gradual forgetting collaborative filtering strategy

刘传昌

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60476-3

摘要 ( 3580 ) PDF (0 KB)( 438 )

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The existing search engines are lack of the consideration of personalization and display the same search results for different users despite their differences in interesting and purpose. By analyzing user’s dynamic search behavior, the paper introduces a new method of using a keyword query graph to express user’s dynamic search behavior, and uses Bayesian network to construct the prior probability of keyword selection and the migration probability between keywords for each user. To reflect the dynamic changes of the user’s preference, the paper introduces non-lineal gradual forgetting collaborative filtering strategy into the personalized search recommendation model. By calculating the similarity between each two users, the model can do the recommendation based on neighbors and be used to construct the personalized search engine.

Distributed GEP query optimization on grid service

邓勇 王汝传

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60477-5

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In order to better solve the problem of distributed query optimization, a query optimization algorithm on gene expression programming (GEP) (QO-GEP) is presented. On the basis of QO-GEP, distributed GEP query optimization on grid service (DGEPQO-GS) is proposed which combines grid service. Simulated experiments show that with the increment of the number of query relation, query time which QO-GEP carries out query decreases apparently. Meanwhile, with the increase of the number of grid nodes, the average querying success rate of DGEPQO-GS increases significantly.

Four-dimensional matrix Walsh transform for lossless compression of color video

李钰 陈贺新 桑爱军 冯华

中国邮电高校学报(英文), 2010, 17 (3). doi： 10.1016/S1005-8885(09)60461-1

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This article presents a coding method for the lossless compression of color video. In the proposed method, four-dimensional matrix Walsh transform (4D-M-Walsh-T) is used for color video coding. The whole n frames of a color video sequence are divided into ‘3D-blocks’ which are image width (row component), image height (column component), image width (vertical component) in a color video sequence, and adjacency (depth component) of n frames (Y, U or V) of the video sequence. Similar to the method of 2D-Walsh transform, 4D-M-Walsh-T is 4D sub-matrices, and the size of each sub-matrix is n. The method can fully utilize correlations to encode for lossless compression and reduce the redundancy of color video, such as adjacent pixels in one frame or different frames of a video at the same time. Experimental results show that the proposed method can achieve higher lossless compression ratio (CR) for the color video sequence.