Journal on Communications

Mobile intelligent agent entity model towards QoS guarantee

Jie LI,Ru-chuan WANG,Zheng-ai BIAN

2006, 27(4): 1-7. doi:1000-436X(2006)04-0001-06

Asbtract ( 0 )

HTML ( 0)

PDF (529KB) ( 160 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

How to implement the configuration of the QoS parameter flexibly in distributed computer network has be-come a problem to be envisaged due to the weak scalability of current approaches.In effort to solve this problem,an in-ner basic model of intelligent agent (IA) was presented and extended by introducing the mobility firstly,and a QoS guar-antee scheme was designed and implemented based on the model subsequently as well.By utilizing the proposed scheme,the IA can sense,predict and configure the traffic.Since the ability of negotiation was also considered and provided,the competition among different devices could be eliminated effectively and the global traffic can be optimized.The results of the simulations show that the proposed model can provide QoS guarantee remarkably.

Cross-layer adaptive transmission scheme combined with SR-ARQ over correlated fading channels

Jun-feng XIAO,Jing QIU,Shi-duan CHENG

2006, 27(4): 7-15. doi:1000-436X(2006)04-0007-09

Asbtract ( 0 )

HTML ( 0)

PDF (973KB) ( 171 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

Conventional adaptive transmission schemes performed poorly in wireless correlated slow-fading channels.A cross-layer adaptive transmission scheme combined with selective repeat automatic repeat request (SR-ARQ) was pro-posed.A multi-state Markov system model for analyzing the performance of systems and optimizing the selection of modulation levels and packet sizes in correlated fading channels was applied,which was also described by a finite-state Markov chain.A general closed-form expression of the average throughput for our suggested scheme was presented.Numerical results show that our adaptive scheme combined with SR-ARQ can obtain good performance in correlated fading channels.

Performance study of real-time traffic in wireless local area network with different kind of stations

Ling-zhi SHENG,FUWei HUANG,Wen LEI,Zhi-mei WU

2006, 27(4): 16-22. doi:1000-436X(2006)04-0016-07

Asbtract ( 0 )

HTML ( 0)

PDF (758KB) ( 36 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

For IEEE 802.11 DCF wireless local area network with different MAC options and applications,a novel model was proposed to analyze the contention performance in saturation channel state.By making use of discrete Markov chain,the performance of throughput,delay and frame dropping ratio was studied in detail.Then this model was validated by simulation results.Furthermore,the model and analysis prove that better performance could be achieved by changing minimum contention window or maximum backoff counter for the real-time flows,which gives an in-depth understand-ing and insights into the effects of different parameters on the performance.

Subband particle filtering for speech enhancement

Nai-gao JIN,Fu-liang YIN,Dong-xia WANG,Zhe CHEN

2006, 27(4): 23-28. doi:1000-436X(2006)04-0023-06

Asbtract ( 0 )

HTML ( 0)

PDF (1372KB) ( 148 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

Rao-Blackwellised particle filtering provided an effective solution for speech enhancement.A novel method was proposed for speech enhancement based on rao-blackwellised particle filters and subband decomposition.In rao-blackwellised particle filters,the dimension of sampling space was reduced by subband decomposition.Subband speech signals were obtained by subband decomposition,then modeled as low-order time-varying AR processes.Rao-blackwellised particle filters were applied to estimate the parameters of AR model and filter the subband speech sig-nals.The enhanced fullband speech signals were finally reconstructed by synthesizing the enhanced subband speech sig-nals.Simulation results show that the proposed method not only has lower computational complexity,but also gives bet-ter speech enhancement performance.

Research on sojourn-time-based dynamic load balancing algorithm in heterogeneous hierarchical wireless networks

Guang-xi ZHU,Guo-qin NING,Hong-ya WANG

2006, 27(4): 29-37. doi:1000-436X(2006)04-0029-08

Asbtract ( 0 )

HTML ( 0)

PDF (994KB) ( 269 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

In order to serve much more mobile stations in heterogeneous hierarchical wireless networks,a dynamic load balancing algorithm based on sojourn time was proposed.Firstly,based on user mobile model,the sojourn time of each mobile station in cells was calculated,then the number of transferred ongoing calls per load balancing period was counted according to the new calls arrival rate of overloaded cell and the workload states of overlapping cells.Finally,those on-going calls with longer sojourn time than the threshold were swithched from overloaded cells to overlapping heterogene-ous under-loaded cells,which could balance the system workload.In addition,in order to decrease the handoff call drop-ping probability,the vertical handoff schemes between different wireless networks were improved.Simulation results show that the proposed dynamic load balancing algorithm performs much better than existing algorithms with respect to the blocking probability,dropping probability and etc.

Modifying the adaptive assembly algorithm based on the length threshold

Yuan-ming WU,Lian-zhu XIAO,Le-min LI

2006, 27(4): 37-41. doi:1000-436X(2006)04-0037-05

Asbtract ( 0 )

HTML ( 0)

PDF (419KB) ( 169 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

An adaptive assembly algorithm based on length thresholds in optical burst switching networks was put for-ward.It could reduce the self-similarity effectively and adjust the length thresholds adaptively according to the properties of the traffic stream.Moreover,it can obtain small packet blocking rate with the same scheduling algorithm.

Congestion control mechanism based on bandwidth estimation in ad hoc networks

Qing-hui WANG,Xue-song PAN,Guang-xing WANG

2006, 27(4): 42-48. doi:1000-436X(2006)04-0042-07

Asbtract ( 0 )

HTML ( 0)

PDF (601KB) ( 330 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

A congestion control mechanism based on bandwidth estimation in ad hoc networks was proposed.In order to get the metric of congestion degree,the available bandwidth was estimated through the work status of wireless link that monitored by the node continuously.The congestion control mechanism was implemented according to packet type.The bandwidth estimation needn't exchange information with other nodes,so the overload of system was low.The results of simulation show that the mechanism has better performance.

Chaotic dynamics behave from sampling phase-detector digital synthesizer loop

Yong-ming TAN,Li-hu DENG

2006, 27(4): 49-53. doi:1000-436X(2006)04-0049-05

Asbtract ( 0 )

HTML ( 0)

PDF (968KB) ( 64 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

Chaotic dynamics behave from sampling phase-detector digital synthesizer loop was analyzed and studied.Based on the method of Ushio and Hiral etc,it was theoretically proved that the system had a bifurcation output when certain condition of the system parameters was satisfied.Hopf bifurcation set of every fixed-point of the system was particularly calculated,and the Lyapunov numbers and Hausdorf dimension of the system were calculated.By simu-lating with computer,the strange attractors,and self-likelihood,and sensitivity of the system rely on its first condition in chaos is observed.The existence of chaos phenomena in sampling phase-detector digital synthesizer loop is further verified.

Novel fragmented looped FDL for OBS networks

Wei YUAN,Jin-sheng LI,Pei-lin HONG

2006, 27(4): 54-59. doi:1000-436X(2006)04-0054-06

Asbtract ( 0 )

HTML ( 0)

PDF (853KB) ( 115 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

A novel fragmented looped FDL to resolve the contention for channels in OBS networks was presented.In or-der to use looped FDL efficiently,a new data channel scheduling algorithm called L_FF was proposed.Computer simula-tions prove that fragmented looped FDL are better than looped FDL and the L_FF algorithm is fitter for fragmented looped FDL than the FF algorithm.

Reliability analysis of core service platform in next-generation network

Meng-hui YANG,Jian-xin LIAO,Nai-xing WU

2006, 27(4): 60-66. doi:1000-436X(2006)04-0060-07

Asbtract ( 0 )

HTML ( 0)

PDF (1023KB) ( 60 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

Based on stochastic PetriNets,an analysis method of steady reliability of core service platform in next-generation network was presented.Modeling and analysis of reliability were set up separately on hardware system for both distributed redundant fault tolerant system and distributed N+1 inter-backup system.A software module in-ter-backup method to tolerate fault was proposed,and the way to express the reliability of this module was obtained.The service software system reliability in terms of its modules was analyzed.And finally,a case is studied to show how the hardware and software cooperation to satisfy the specific reliability requirement.

Services differentiated dynamic fair scheduling in WCDMA systems

Jie WANG,Ze-dong YAN,Chun-ming ZHAO

2006, 27(4): 67-73. doi:1000-436X(2006)04-0067-07

Asbtract ( 0 )

HTML ( 0)

PDF (840KB) ( 22 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

In order to design scheduling algorithm in CDMA systems,it's necessary to take channel condition and power of the link into consideration.Based on the concept of power index and nominal capacity,a modified code division gen-eralized processor sharing-based scheduling (CDGPS) scheme with the generic name services differentiated CDGPS (SD-CDGPS) is proposed,which involves services differentiation model,nominal capacity dynamic allocation model and compensation model.The simulation results show that bounded delay can be provisioned for delay sensitive services and short-term and long-term fairness can be assured by using the SD-CDGPS schemes.

Micro-mobility handoff method based on dynamic distributed structure

Jian-sheng XUE,Guang-xing WANG

2006, 27(4): 74-79. doi:1000-436X(2006)04-0074-06

Asbtract ( 0 )

HTML ( 0)

PDF (751KB) ( 12 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

A micro-mobility handoff method based on dynamic distributed structure was presented.According to the first registration information while the mobile node entering the microcosmic LAN,mobile node dynamically choose a mi-cro-mobility gateway,adjusted the structure of microcosmic LAN and realizes load-balance.From the comparison and the simulation of handoff delay,it is clear that this method decreases the delay.

Packet scheduling based on matrix decomposition in optical switches

Qing-xu XIONG,Jin-xin FENG

2006, 27(4): 80-86. doi:1000-436X(2006)04-0080-07

Asbtract ( 0 )

HTML ( 0)

PDF (597KB) ( 281 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

The packet scheduling in optical switches was investigated based on matrix decomposition technology.First a simple matrix decomposition algorithm was proposed for a doubly stochastic matrix.And then a dynamical online sched-uling algorithm called p-LQF was proposed by choosing the permutation with the largest backlog.It was shown by simu-lation results that p-LQF had closed to or even lower average packet delay than LQF,much lower than i-LQF.The p-LQF algorithm was proved to be stable for any admissible traffic satisfies the strong law of largest numbers.It was also dem-onstrated that p-LQF was robust to dynamical packet arrivals,and stable for the matrix with bounded traffic quantization.

Robust image watermarking algorithm based on contourlet transform

Hai-feng LI,Wei-wei SONG,Shu-xun WANG

2006, 27(4): 87-94. doi:1000-436X(2006)04-0087-08

Asbtract ( 0 )

HTML ( 0)

PDF (1460KB) ( 88 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

A novel robust watermarking algorithm in Contourlet domain was proposed.The Contourlet transform was adopted by virtual of its advantages over the wavelet transform.A flexible multiresolution,local,and directional image expansion was obtained using contour segments.The watermark was inserted through content-adaptive multiplicative embedding.The Contourlet coefficients were modeled as generalized Gaussian distribution (GGD) with zero mean.Then the maximum likelihood watermark detection method was developed.Under the Neyman-Pearson criterion,the decision rule was optimized by minimizing the probability of missing the watermark for a given false detection rate.Experimental results demonstrate that the proposed algorithm is invisible,and robust to signal processing.

Analysis of stop criterions in the decoder of parallel concatenated LDPC codes

Jin LI,Han HUA,Jing-yu HUA,Xiao-hu YOU

2006, 27(4): 95-100. doi:1000-436X(2006)04-0095-06

Asbtract ( 0 )

HTML ( 0)

PDF (895KB) ( 124 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

To reduce the computation complexity of the decoder of parallel concatenated Gallager code,two kinds of low complexity stop criterion were proposed.The criterions decide whether the iteration of the decoder should be stopped based on the change of the variance of extrinsic information.The computer simulation results prove that the stop criteri-ons could reduce the computation complexity of the PCGC decoder with negligible performance loss.

Audio steganalysis based on auto-correlation property of sdteganographic tools

Xue-min RU,Yue-ting ZHUANG,Fei WU

2006, 27(4): 101-106. doi:1000-436X(2006)04-0101-06

Asbtract ( 0 )

HTML ( 0)

PDF (560KB) ( 582 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

After investigating the changes of audio statistics features,auto-correlation property in steganographic soft-ware tools was found when different random message was embed in same audio with same steganographic tool.Based on this property,a novel steganalysis scheme was proposed which was implemented by using support vector machine (SVM) to classify stego-audio from clear audio with the audio and its linear prediction statistics features.This scheme can not only detect the existence of hidden messages,but also identify the tools used to hide them.As shown by the experimental results,the proposed method can be very effectively used to detect hidden messages embedded by Hide4PGP,Stegowav and Steghide.

High-speed radix-16 design of a scalable Montgomery multiplier

Yi-bo FAN,Xiao-yang ZENG,Yu YU

2006, 27(4): 107-113. doi:1000-436X(2006)04-0107-07

Asbtract ( 0 )

HTML ( 0)

PDF (555KB) ( 348 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

An improved version of Montgomery multiplier was proposed basing the Tenca-Todorov-Ko?'s word based radix-8 Montgomery multiplier.Radix-16 was used for fast without adding any hardware,and the performance was im-proved up to 26% comparing to the Tenca-Todorov-Ko?'s design.On one hand,shorter critical path and faster frequency were got through adjusting the data-path,on the other hand,a half memory cost by preprocessing the data was saved-which would be stored in FIFO.The improved design was scalable to do any precision modular multiplication and RSA encryption.At last,a 2048-bit RSA test chip was implemented using 0.25 μm technology CMOS standard cell.The chip performs 2048-bit modular exponentiation in 28ms under 125MHz clock period.

Improvement to the coverage radius and forward-link capacity of the conventional cell system

De-run QIU,Nan-lan WANG

2006, 27(4): 114-118. doi:1000-436X(2006)04-0114-05

Asbtract ( 0 )

HTML ( 0)

PDF (920KB) ( 154 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

By way of the reasonable supposition and exemplification analysis,it stated clearly that it can realize the fast switch across areas after the general expandable hardware platform in software radio was applied to traditional commu-nication cell network.And it would cause lower interruption rates and increase the coverage radius of the system com-pared with traditional honeycomb systems.Finally it is proved that the closed-loop transmission scheme can improve the receiving the energy and the interference ratio and increase the forward-link capacity of the system.

Adaptive multistage median filtering based on direction

Hong-lin WAN,Yu-hua PENG,Rui GUO

2006, 27(4): 119-123. doi:1000-436X(2006)04-0119-05

Asbtract ( 0 )

HTML ( 0)

PDF (893KB) ( 157 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

An adaptive multistage median filtering based on direction was presented in terms of traditional method's dis-advantage in directions of protected lines.This method estimates a line's direction through a small rectangle window and then chooses a proper filtering mode in a larger one,which makes a sub-window have the identical direction with line.Computer experiments have showed its advantages over traditional multistage median filtering in preserving an image's edges in each direction more effectively,and the same effective ability to smooth noise.

High performance distributed mutual exclusion algorithm based on quorum and dynamic token

Mei-an LI,Xin-song LIU,Zheng WANG

2006, 27(4): 124-130. doi:1000-436X(2006)04-0124-07

Asbtract ( 0 )

HTML ( 0)

PDF (985KB) ( 611 )

Knowledge map

References | Related Articles | Metrics

A new algorithm has been proposed to resolve the distributed mutual exclusion problem.In this algorithm,through introducing the dynamic token concept and changing the functions or transfer directions of some other messages such as reply,release in the distributed mutual exclusion algorithms based on quorum or competition,the message com-plexity of Makawa type algorithms can be reduced from O(3K～5K) to O(2K～4K) and the synchronization delay from 2T to T.At the same time,the site fault-tolerant ability of this distributed mutual exclusion algorithm can be increased to N-2.and this algorithm is still deadlock and starvation free as all other Makawa type algorithms.Trough running this al-gorithm in practice and compare it's output with other algorithms,we know this algorithm is very useful in distributed operation system.

Compact frequency notched ultra-wideband antenna for multiple application

Yong CHENG,Wen-jun LV,Chong-hu CHENG,Wei CAO

2006, 27(4): 131-135. doi:1000-436X(2006)04-0131-05

Asbtract ( 0 )

HTML ( 0)

PDF (956KB) ( 133 )

Knowledge map

Figures and Tables | References | Related Articles | Metrics

A compact frequency notched microstrip slot antenna for multiple application was proposed.The antenna was similar to a conventional microstrip slot antenna.To achieve frequency notched characteristic,a cross wide slot and a rectangular stub with a T shaped stub embedded it were employed.It had been studied both numerically and experimen-tally for its impedance bandwidth,radiation patterns and gain.As will be seen,an operation bandwidth from 2.39 to 12GHz for stand wave ratio lower than 2,in which a frequency notched band from 5.15 to 5.95 GHz,has been achieved.The antenna can also be used for 2.4GHz WLAN application.Good radiation performance over the entire fre-quency range has also been achieved.

Research on decrease package size of self-healing key management solution in MANET

Shun-man WANG,Ran TAO,Yue WANG

2006, 27(4): 136-146. doi:1000-436X(2006)04-0136-05

Asbtract ( 0 )

HTML ( 0)

PDF (939KB) ( 145 )

Knowledge map

References | Related Articles | Metrics

An efficient self-healing key management solution based on dynamic topology and low process requirement of MANET are proposed,which can decrease the communications cost to traditional method.Also,the method of decrease package size is given,which is a valuable method to the MANET circumstance,since the wireless channel is very limited.Security and the applicability of the method are proved in the end.

Current Issue