Random Access Channel （RACH） is an uplink contention-based transport channel usually used for initial channel access, bandwidth request, etc. How to use RACH resources effectively is very important in wireless corrn...Random Access Channel （RACH） is an uplink contention-based transport channel usually used for initial channel access, bandwidth request, etc. How to use RACH resources effectively is very important in wireless corrnunication systel In this paper, a dynamical RACH allocation scheme is proposed for Orthogonal Frequency-Division Multiple Access （OFDMA） systen. Based on the PseudoBayesian algorithm, this mechanism predicts the number of RACHs for the next frame according to the current load. A new dynamic RACH assignment algorithm and an adaptive access probability method are adopted by the proposed scheme to irrprove the utilization ratio of RACH resources and increase the successful access rate. Numerical simulation shows that the proposed strategy achieves both improvement in the utilization ratio of RACHs and reduction in the access delay compared with other RACH allocation schemes.展开更多
We describe the design of a multiple maneuvering targets tracking algorithm under the framework of Gaussian mixture probability hypothesis density(PHD) filter.First,a variation of the generalized pseudo-Bayesian estim...We describe the design of a multiple maneuvering targets tracking algorithm under the framework of Gaussian mixture probability hypothesis density(PHD) filter.First,a variation of the generalized pseudo-Bayesian estimator of first order(VGPB1) is designed to adapt to the Gaussian mixture PHD filter for jump Markov system models(JMS-PHD).The probability of each kinematic model,which is used in the JMS-PHD filter,is updated with VGPB1.The weighted sum of state,associated covariance,and weights for Gaussian components are then calculated.Pruning and merging techniques are also adopted in this algorithm to increase efficiency.Performance of the proposed algorithm is compared with that of the JMS-PHD filter.Monte-Carlo simulation results demonstrate that the optimal subpattern assignment(OSPA) distances of the proposed algorithm are lower than those of the JMS-PHD filter for maneuvering targets tracking.展开更多
时隙ALOHA需要使用控制算法以保证系统获得稳定吞吐量,而控制算法的关键是精确估计系统中的节点数。针对系统中的节点数在某时刻发生剧变时,传统的伪贝叶斯控制算法(pseudo Bayesian control algorithms,PBCA)存在调节时间较长的问题,...时隙ALOHA需要使用控制算法以保证系统获得稳定吞吐量,而控制算法的关键是精确估计系统中的节点数。针对系统中的节点数在某时刻发生剧变时,传统的伪贝叶斯控制算法(pseudo Bayesian control algorithms,PBCA)存在调节时间较长的问题,提出分阶快速自适应伪贝叶斯控制算法(ranked fast adaptive PBCA,RFA-PBCA),首先设置一个门限值nth把信道的竞争情况分成高强度和低强度2种类型,再利用游程技术将信道分成空闲(冲突)和非空闲(非冲突)2种状态。当信道检测到c(c=6)个空闲时隙时,若估计节点数n大于nth,则节点将其传输数据概率增大为原先的2倍;同理,当信道检测c(c=6)个冲突时隙后,将其传输数据概率设为原先的1/2,其他情况下则采用PBCA进行调整。仿真结果表明,RFA-PBCA能够很好适应系统节点急剧变化的应用场景,其性能明显优于传统的PBCA。展开更多
基金Acknowledgements This paper was supported by the National Natural Science Foundation of China under Cants No.60971125, No.61121001 the National Key Project under Cant No. 2011ZX03005-005+2 种基金 the project under Cant No. 201105.Acknowledgements This paper was supported by the National Natural Science Foundation of China under Crants No.60971125, No.61121001 the National Key Project under Cant No. 2011ZX03005-005 the project under Cant No. 201105.
文摘Random Access Channel （RACH） is an uplink contention-based transport channel usually used for initial channel access, bandwidth request, etc. How to use RACH resources effectively is very important in wireless corrnunication systel In this paper, a dynamical RACH allocation scheme is proposed for Orthogonal Frequency-Division Multiple Access （OFDMA） systen. Based on the PseudoBayesian algorithm, this mechanism predicts the number of RACHs for the next frame according to the current load. A new dynamic RACH assignment algorithm and an adaptive access probability method are adopted by the proposed scheme to irrprove the utilization ratio of RACH resources and increase the successful access rate. Numerical simulation shows that the proposed strategy achieves both improvement in the utilization ratio of RACHs and reduction in the access delay compared with other RACH allocation schemes.
基金Project supported by the National Natural Science Foundation of China(Nos.61175008,60935001,and 61104210)the Aviation Foundation(No.20112057005)the National Basic Research Program(973) of China(No.2009CB824900)
文摘We describe the design of a multiple maneuvering targets tracking algorithm under the framework of Gaussian mixture probability hypothesis density(PHD) filter.First,a variation of the generalized pseudo-Bayesian estimator of first order(VGPB1) is designed to adapt to the Gaussian mixture PHD filter for jump Markov system models(JMS-PHD).The probability of each kinematic model,which is used in the JMS-PHD filter,is updated with VGPB1.The weighted sum of state,associated covariance,and weights for Gaussian components are then calculated.Pruning and merging techniques are also adopted in this algorithm to increase efficiency.Performance of the proposed algorithm is compared with that of the JMS-PHD filter.Monte-Carlo simulation results demonstrate that the optimal subpattern assignment(OSPA) distances of the proposed algorithm are lower than those of the JMS-PHD filter for maneuvering targets tracking.
文摘时隙ALOHA需要使用控制算法以保证系统获得稳定吞吐量,而控制算法的关键是精确估计系统中的节点数。针对系统中的节点数在某时刻发生剧变时,传统的伪贝叶斯控制算法(pseudo Bayesian control algorithms,PBCA)存在调节时间较长的问题,提出分阶快速自适应伪贝叶斯控制算法(ranked fast adaptive PBCA,RFA-PBCA),首先设置一个门限值nth把信道的竞争情况分成高强度和低强度2种类型,再利用游程技术将信道分成空闲(冲突)和非空闲(非冲突)2种状态。当信道检测到c(c=6)个空闲时隙时,若估计节点数n大于nth,则节点将其传输数据概率增大为原先的2倍;同理,当信道检测c(c=6)个冲突时隙后,将其传输数据概率设为原先的1/2,其他情况下则采用PBCA进行调整。仿真结果表明,RFA-PBCA能够很好适应系统节点急剧变化的应用场景,其性能明显优于传统的PBCA。
