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25 June 2012, Volume 33 Issue 6

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academic paper

Effect of mutual coupling and antenna correlation on MIMO system in three-dimensional spatial channel models

Jie ZHOU,Jing-feng CHEN,Lin QIU,Kikuchi HISAKAZU

2012, 33(6):  1-10.  doi:1000-436X(2012)06-0001-10

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A channel model for frequency nonselective Rayleigh fading MIMO channel was set up and the channel model setting was extended to three-dimensional space.The mutual coupling between antenna elements was analyzed based on the equivalent network model of the multiple-antenna.The general spatial correlation expressions of channel model with the impact of mutual coupling were derived in the three-dimensional spatial channels.When the receivers were different antenna arrays,the effect of the angular parameters associated with the mean azimuth of arrival(MAOA),azimuth spread(AS),meant elevation of arrival(MEOA)and elevation spread(ES)on the MIMO system capacity was investigated.Numerical results verifiy the impact of different angle spread on spatial correlation with the mutual coupling and indicate that the system capacity is more dependent on the MAOA and MEOA than the AS and ES.

Computing on the joint quadratic complexity of multiple periodic sequences

Li-hua DONG,Yu-pu HU,Yong ZENG

2012, 33(6):  11-18.  doi:1000-436X(2012)06-0011-08

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An algorithm for determining the joint quadratic complexity of the prescribed multiple periodic sequences over any finite field was presented by using the algorithm for computing the quadratic complexity of the prescribed single sequence proposed by Rizomiliotis and the methods for determining the solutions of the linear equations.The total processing time requirement is cubics function of the sequence length at most.

Secure cross-domain communication mechanism for Web mashups

Jian-hua SUN,Zhi-rong LIU,Hao CHEN

2012, 33(6):  19-29.  doi:1000-436X(2012)06-0019-11

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Many methods were used in cross-domain communication,whereas they were hardly to meet the security and high performance requirements.To this end,a secure cross-domain communication(SCDC)mechanism was proposed for Web mashups.It encapsulates content from different trust domains as secure components,achieves cross-domain communication with layered communication stack,and shares fine-grained objects by wrapping objects.SCDC mechanism supports secure cross-domain communication,shares objects between mashups and components without any browser modifications.Experiments show that the mechanism improves the communication efficiency more than five-fold,and only incurs limited overhead.

Bursty-link-aware adaptive link quality estimation method

Ting-pei HUANG,Dong LI,Zhao-liang ZHANG,Li CUI

2012, 33(6):  30-39.  doi:1000-436X(2012)06-0030-10

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A bursty-link-aware and adaptive link quality estimation method,named EasiLQE,was proposed.The beacon packets are sent by nodes in a long-term period to probe the link quality.Meanwhile,nodes passively measure the mean value of RSSI of received packets.If the mean value of RSSI is lower than a certain threshold,the EasiLQE initiates the link quality estimation process in a short-term period.Finally,the EasiLQE uses error-based filter to estimate the link quality in future.The experimental results show that the EasiLQE can react quickly and accurately to persistent link quality changes in a short time,and also can smooth the occasional link quality fluctuations,which are not acute,to keep the link quality estimator stable,and decrease the estimation costs.

Inter-block 4-erasure-correcting coding scheme for real-time bulk data transfer

Gang CHEN,Jun-feng ZHU,Shi-le ZHANG,Bai-feng WU

2012, 33(6):  40-49.  doi:1000-436X(2012)06-0040-10

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Most of the existing erasure-correcting codes were limited by encoding/decoding complexities and encoded data size.They were not suitable for use in the real-time applications that orient bulk data based on blocks or packages.Therefore,a novel inter-block 4-erasure-correcting coding scheme for real-time bulk data transfer was presented.Based on single parity-check codes incorporated with the features of GF(2＜sup＞8＜/sup＞)field in finite field,the present coding scheme could tolerate simultaneous failures of four blocks with only four redundancy blocks for a group of continuous data.Meanwhile,its encoding/decoding complexities had linear relationship with respect to the size of data blocks and it supported arbitrary size of data.Furthermore,it was proved to have MDS property,thus achieving optimal erasure-correcting capability with the same redundancy information.Theoretical and experimental analysis showed that the present coding scheme could code with 27 continuous data blocks at most.

Differential detection scheme for distributed MIMO systems in fast fading channel

Dong-dong DOU,Jun-bo LIU,Da-ming WANG,Zhao-xun LI

2012, 33(6):  50-54.  doi:1000-436X(2012)06-0050-05

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In the fast fading distributed MIMO system,it is difficult to keep the channel fading coefficient unchanged in adjacent space-time blocks due to the rapid changed state information,which leads to the traditional distributed MIMO differential detection scheme is not suitable any.Aiming at this matter,an improved differential detection scheme was proposed.By recombining space-time codes which were differential modulated by phase,this differential detection scheme reduced the influence from fast fading channels at the cost of larger processing delay and additional transmission power.Theoretical analysis and some computer simulation results show that this scheme can improve the BER performance remarkably in fast fading channels compared with the existing the conventional differential space time detection.

Hidden Markov model based P2P flow identification technique

Bo XU,Ming CHEN,Xiang-lin WEI

2012, 33(6):  55-63.  doi:1000-436X(2012)06-0055-09

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To identify various P2P flows accurately in real-time,a hidden Markov model(HMM)based P2P flow identification technique was proposed.This approach made use of packet size,inter-arrival time and arrival order to construct flow identification model,in which discrete random variable was used to depict the characteristics of HMM state.A framework called HMM-FIA was proposed,which could identify various P2P flows simultaneously.Meanwhile,the algorithm for selecting the number of HMM state was designed.In a controllable experimental circumstance in the campus network,HMM-FIA was utilized to identify P2P flows and was compared with other identification methods.The results show that discrete random variable can decrease the model constructing time and improve the time-cost and accuracy in identifying unknown flows,HMM-FIA can correctly identify the packet flows produced by various P2P protocols and it can be adaptive to different network circumstance.

Lossless image authentication algorithm based on adaptive combinations of image basic blocks

Jian-gao LUO,Guo-qiang HAN,Yan WO,Xiang-yang LI

2012, 33(6):  64-72.  doi:1000-436X(2012)06-0064-09

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As the existing block-wise lossless image authentication algorithms were inadequate in the division of image authentication blocks,a novel lossless image authentication algorithm based on adaptive combinations of image basic blocks was proposed.The image authentication block was composed of some basic image blocks by the source image characteristics and requirements of watermarking image fidelity,and the authentication code was generated by a digital signature algorithm and embedded into the authentication block via a lossless watermarking algorithm.Moreover,the robust transmission of the image ID was achieved via multi-embedding,and using the ID and authentication block ID the image authentication algorithm could prevent vector quantizationattack.Theoretical analyses and experimental results demonstrate that the algorithm not only improves the existing tamper localization accuracy but also has strong adaptability and can resist vector quantization attack.

Cognitive network channel allocation method based on the queuing delay and game analysis

Jun LIU,Xiu-feng XIE

2012, 33(6):  73-81.  doi:1000-436X(2012)06-0073-09

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A new dynamic spectrum allocation method for distributed cognitive radio networks was proposed.In the method,packet transmission success rate is chosen as the utility function,the transmission delay is resolved by the priority queuing model,and the user’s channel allocation strategy is achieved by distributed game.Compared with other algorithms,the policy iteration process is improved effectively,and a dynamic strategy adjustment step is adopted.Each network user dynamically adjust their channel choose strategy based on current perception of the remaining user’s strategy.The proposed algorithm lets channel selection strategy converge more quickly to equilibrium point,and effectively suppresses the policy shocks.The simulation results validate the proposed algorithm.

Novel cooperative caching strategies for video streaming distribution based on reconfiguration routers

Zhi-cong HE,Guang-zhao GU,Xin WANG,Jin ZHAO,Xiang-yang XUE

2012, 33(6):  82-90.  doi:1000-436X(2012)06-0082-09

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A novel cooperative caching scheme based on reconfiguration routers was proposed to accelerate the delivery of streaming media.Through cooperative caching for popular videos among the routers,the server capability,especially bandwidth requirements were decreased.Moreover,the traffic over the backbone network was dramatically reduced and user experience was also improved due to the edge routers providing services for the user quickly.Furthermore,implemented a prototype system is implemented to evaluate the scheme,and the results show great improvement over the state-of-the-art solutions.

Transmission control protocol based on hop-by-hop for satellite networks

Lu WANG,Yue-mei HU,Li-xiang LIU,Xiao-hui HU

2012, 33(6):  91-102.  doi:1000-436X(2012)06-0091-12

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A transmission control protocol named TPSN(transmission control protocol for satellite networks)was proposed,which applied asynchronous hop-by-hop ACK,and SNACK based on checking window size to reduce overhead of control message and achieve reliable transmission.In addition,TPSN transmitted load information on the base of hop-by-hop scheme to maintain high network resources utilization,fairness among different data flows with heterogeneous RTT and congestion free.The good performance of TPSN,in terms of link utilization,transmission effectiveness and fairness,was verified via a simulated satellite network with high link error rate,large delay and intermittent links.

On coding over the spatial-temporal diversity for reliable transmission scheme in low-duty-cycle WSN

Yu-bo YAN,Pan-long YANG,Lei ZHANG,Zheng-lun QIU,Shan-lin HONG

2012, 33(6):  103-111.  doi:1000-436X(2012)06-0103-09

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A reliable data delivery scheme for low-duty-cycle wireless sensor networks(WSN)was proposed.Using this scheme,the unique spatial-temporal diversity in low-duty-cycle WSN was explored and exploited.Combining with coding schemes,the proposed scheme could achieve higher energy efficiency and lower delivery delay.The coding block allocation problem over multiple paths was formulated.As it was NP-hard,an approximate algorithm to tackle this difficulty was proposed.The impact of network parameters was further analyzed with experimental methods.Extensive simulations also show that,the coding over the spatial-temporal diversity scheme could achieve relatively reliable and low delay delivery with relatively less energy.

Research on differential Pattern time delay shift coding underwater acoustic communication

Jing-wei YIN,Xiao ZHANG,Xue-li SHENG,Chao SUN

2012, 33(6):  112-117.  doi:1000-436X(2012)06-0112-06

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A differential Pattern time delay shift coding(DPDS)method with a non-fixed code width based on the traditional Pattern time delay shift coding was proposed.The information is carried by the time delay between adjacent code element,the different linear frequency modulation(LFM)signal is used for adjacent code division.The DPDS system has an ability anti inter-symbol interference(ISI)and the Doppler effects.The computer simulation and lake tests prove that the DPDS system can improve the communication rate,inhibit the ISI caused by the multi-path channel and anti the Doppler effects.It is proved that the system has an effectiveness and robustness.

Parallel route distributing model in reconfigurable cluster router

Wen-long CHEN,Ming-wei XU,Ke XU

2012, 33(6):  118-124.  doi:1000-436X(2012)06-0118-07

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Long distribution delay and load unbalance of router cards were the key problems of traditional route distribution techniques.Especially,in reconfigurable cluster routers,the number of linecards significantly increased,which made the problem highlighted.To address this issue,the TPRD(tree-based parallel route distribution)model was proposed after systematically analyzing existing route distribution methods and the cluster router architecture.In TPRD,all cards of cluster router were constructed to an unbalanced distribution tree and routes were transferred form the root node to leaf nodes.The algorithms and deployment approaches for implementation of TPRD were presented.The NS2 simulation results demonstrated TPRD achieved an expected performance.

Downlink capacity analysis in distributed antenna systems

Jun-bo WANG,Jin-yuan WANG,Xi-bin ZHAO,Ming GU,Ming CHEN,Yuan JIAO

2012, 33(6):  125-132.  doi:1000-436X(2012)06-0125-08

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The downlink capacity was analyzed in distributed antenna systems(DAS).Firstly,a composite channel model was established,which took path loss,lognormal shadowing and Rayleigh fading into account.Then,based on the channel model,both the ergodic capacity and outage capacity were analyzed.After that,considering the distribution of mobile stations(MS)in the system,the approximate analytical expressions of the ergodic capacity and outage capacity were derived by making use of selective diversity(SD)transmission scheme for distributed antennas.Numerical results show that both the two approximate analytical expressions can provide sufficient precision for evaluating the system performance of DAS.

Coding-aware secure routing for multi-hop wireless networks

Xian GUO,Tao FENG,Zhan-ting YUAN

2012, 33(6):  133-142.  doi:1000-436X(2012)06-0133-10

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To address security issues of DCAR in“coding+routing”discovery,a new security destination was proposed and a distributed coding-aware secure routing(DCASR)was designed.DCASR guarantees discovery of correct coding opportunity and establishment of trusted routes by using cryptography.To analyze the properties of DCASR,LS2(logic of security systems)was extended,and a new logic LS2-RP(LS2 for routing protocol)was proposed.In LS2-RP,the concepts of location and neighboring location of thread were introduced.The dynamic topology of multi-hop wireless networks was described by the set of neighbors for thread.The broadcast rule of neighboring location threads modeled the feature of wireless broadcast communication.Finally,DCASR was described by programming language of LS2-RP and security properties were defined by predicates and modal formulas of LS2-RP.Security of DCASR was analyzed by using the proof system of LS2-RP.DCASR can satisfy our secure destination.

engineering report

Research on rate-distortion cost estimation model for H.264

Xin-zi ZHENG,Zhi-xin SUN

2012, 33(6):  143-149.  doi:1000-436X(2012)06-0143-07

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A new rate distortion cost estimation model was proposed.To provide more accurate estimation of the number of coding bits for encoding intra / inter macro blocks,firstly a new bit rate estimation model was proposed.The rate estimation was a linear combination of existing coding parameters,which were more accurately related to entropy coding and transform coefficients.Secondly a new rate distortion cost estimation model which had superior performance was given.Finally,a detailed analysis on the rate distortion cost estimation model from many aspects such as the effect and the performance was taken.Experimental results show that the encoding speed is greatly accelerated in ensuring little change both in PSNR and coding bits.

Joint reduction of peak-to-average power ratio and out-of-band power based on subcarrier weighting in OFDM systems

Qing LI,Han-ying HU

2012, 33(6):  150-156.  doi:1000-436X(2012)06-0150-07

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Considering the conflict of PAPR and OBP reductions in OFDM systems,a new method based on subcarrier weighting was proposed for the joint reduction.The symbols on subcarriers were multiplied by optimal weighting vector to reduce PAPR and OBP jointly,and an improved GA was used to calculate the optimal weighting vector for lower complexity.It was more effective in spectrum utility and did not need any transmission of side information.Furthermore,with trade-off parameter,it offered more flexibility to control the reduction by changing the relative weighting of the two optimization criteria.The simulation results indicate that,compared with a system that performs two separate optimization steps,the proposed method can significantly enhance the amount of PAPR and OBP reduction with lower computation complexity.It is simple to implement,which makes it very practical.

Study on a multi-satellite constrained space-time anti-jam algorithm

Guo-sheng HUANG,Zheng-rong YI,Tao SHUAI,Zhen-cai ZHU

2012, 33(6):  157-163.  doi:1000-436X(2012)06-0157-07

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A multi-satellite constrained space-time anti-jam algorithm was proposed for global navigation satellite system(GNSS)receivers.Firstly the equivalent GSC structure of multi-satellite constrained LCMV principle was considered and its forward decomposition process was simplified and improved,so the computation complexity was reduced to approach single-satellite constrained problem.Then the Householder multi-stage Wiener filtering(MWF)algorithm was proposed to solve the classical Wiener filtering problem in the GSC structure,and an efficient order-recursive implementation structure was obtained by improving the backward recursive process using the decomposition property of MWF,so the real-time performance was greatly promoted and the reduced rank could be adaptively estimated from the output of MSE.The complete procedure of the proposed algorithm is summed up and its validation is verified by simulations.

Academic communication

Dynamic group key management scheme for homogeneous wireless sensor networks

Tao WEN,Yong ZHANG,Quan GUO,Feng-kun LI

2012, 33(6):  164-173.  doi:1000-436X(2012)06-0164-10

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Focuses on the study of GKM scheme applicable to homogenous network model，proposed a clear and complete key management model for dynamic groups for the first time and exposed a dynamic group key management(DGKM)scheme based on symmetric polynomials.The scheme provided a solution to related group key management issues,such as key establishment,key updating,node addition and node revocation,for a multicast group consisting of any number(bigger than 2 and less than the total number)of nodes.Besides,the scheme supported node mobility as well as scalability and coped well with the unreliable wireless multicast communication.Group members can get group key by computing and with little wireless communication,therefore,greatly reduced the cost of key agreement.The analysis shows the scheme has very good performance in terms of storage,computation as well as communication and is more suitable to wireless sensor networks with limited capability.

Cryptographic secrecy of steganographic matrix encoding

Jia-yong CHEN,Jiu-fen LIU,Yue-fei ZHU,Wei-ming ZHANG

2012, 33(6):  174-179.  doi:1000-436X(2012)06-0174-06

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Based on an information theory model,the cryptographic security of matrix encoding,which can be applied in steganographic codes or wet paper codes,under different attack conditions was studied.The cryptographic security about matrix encoding under the condition of known-cover attack with key equivocation,message equivocation and unicity distance of stego-key was presented.The result that n groups of differential equations could sufficiently recover the share key of matrix encoding under the condition of chosen-stego attack was pointed out.

Robust algorithm for gain-and-phase errors estimation against the direction deviations of calibration sources

Ding WANG,Hui YAO,Ying WU

2012, 33(6):  180-190.  doi:1000-436X(2012)06-0180-11

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The direction deviations of the calibration sources would significantly degrade the calibration accuracy of array gain-and-phase errors.Aiming to this problem,a robust calibration algorithm for gain-and-phase errors against the location deviations was presented under the assumption that the prior probability distribution of the location deviation was known.The idea of the robust algorithm was based on subspace fitting criterion and Bayesian estimation theory framework.The gain-and-phase errors were obtained through calculating the eigenvector associated with the minimum eigenvalue of some real symmetric matrix without estimating the locations of calibration sources.The closed-form Cramér-Rao bound(CRB)for the unknown parameters was derived,and the asymptotic distributions of the robust algorithm as well as the Cheng method were also given in the presence of direction deviations.Both the theory analysis and the simulation experiments validate that the asymptotic performance of the robust algorithm can reach the CRB under some moderate conditions and outperform the Cheng method when the location deviations exist.

Parameters design and performance analysis of the timing recovery loop based on Gardner timing detector

Yong-ming FU,Jiang ZHU,Ying-jue JU

2012, 33(6):  191-198.  doi:1000-436X(2012)06-0191-08

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In-depth research was carried out into parameters design in the feedback timing recovery loop based on Gardner timing error detector,according to the theory of digital phase-lock loop.MATLAB based simulation was performed for both first-order and second-order loop.Comprehensive analysis of the influence from loop order and noise-equivalent bandwidth on synchronization performance indicates the relationship between synchronization performance and noise-equivalent bandwidth,which provides a theoretic reference for timing recovery loop design.