Wireless Body Area Networks(WBANs) are expected to achieve high reliable communications among a large number of sensors.The outage probability can be used to measure the reliability of the WBAN.In this paper,we optimi...Wireless Body Area Networks(WBANs) are expected to achieve high reliable communications among a large number of sensors.The outage probability can be used to measure the reliability of the WBAN.In this paper,we optimize the outage probability with the harvested energy as constraints.Firstly,the optimal transmit power of the sensor is obtained while considering a single link between an access point(AP) located on the waist and a sensor attached on the wrist over the Rayleigh fading channel.Secondly,an optimization problem is formed to minimize the outage probability.Finally,we convert the non-convex optimization problem into convex solved by the Lagrange multiplier method.Simulations show that the optimization problem is solvable.The outage probability is optimized by performing power allocation at the sensor.And our proposed algorithm achieves minimizing the outage probability when the sensor uses energy harvesting.We also demonstrate that the average outage probability is reduced with the increase of the harvested energy.展开更多
Using state assignment to minimize power dissipation and area for finite state ma-chines is computationally hard. Most of published results show that the reduction of switchingactivity often trades with area penalty. ...Using state assignment to minimize power dissipation and area for finite state ma-chines is computationally hard. Most of published results show that the reduction of switchingactivity often trades with area penalty. In this paper, a new approach is proposed. Experimentalresults show a significant reduction of switching activity without area penalty compared withprevious publications.展开更多
This paper proposes a novel mapping scheme for bit-interleaved coded modulation with iterative decoding(BICM-ID).The symbol mapping is composed of two QPSK with different radiuses and phases,called cross equalization-...This paper proposes a novel mapping scheme for bit-interleaved coded modulation with iterative decoding(BICM-ID).The symbol mapping is composed of two QPSK with different radiuses and phases,called cross equalization-8PSK-quasi-semi set partitioning(CE-8PSK-Quasi-SSP).Providing the same average power,the proposed scheme can increase the minimum squared Euclidean distance(MSED)and then improve the receiving performance of BICM-ID compared with conventional symbol mapping schemes.Simultaneously,a modified iteration decoding algorithm is proposed in this paper.In the process of iteration decoding,different proportion of the extrinsic information to the systematic observations results in distinct decoding performance.At high SNR(4~9dB),the observation information plays a more important role than the extrinsic information.Simulation results show that the proportion set at 1.2 is more suitable for the novel mapping in BICM-ID.When the BER is 10^(-4),more than 0.9dB coding gain over Rayleigh channels can be achieved for the improved mapping and decoding scheme.展开更多
甚高频数据交换-卫星部分(VHF Data Exchange-Satellite,VDE-SAT)是下一代海事通讯系统甚高频数据交换系统(VHF Data Exchange System,VDES)的关键组成部分,用于实现航海船站与海事卫星以及航海船站间的相互通信和数据传输,其链路层接...甚高频数据交换-卫星部分(VHF Data Exchange-Satellite,VDE-SAT)是下一代海事通讯系统甚高频数据交换系统(VHF Data Exchange System,VDES)的关键组成部分,用于实现航海船站与海事卫星以及航海船站间的相互通信和数据传输,其链路层接入性能对于VDES的实际应用效果有着重要影响。针对当前实际应用中航海船站随机接入VDES系统容易出现峰值吞吐量较低和线性工作区较短的问题,该文在深入分析国际电信联盟制定的ITU-R M.2092标准规范和航海船站接入VDE-SAT的技术特性,以及现有无线网络随机接入协议的基础上,提出一种适用于VDE-SAT的基于功率分集和直接序列扩频的竞争解决分集时隙ALOHA(Power Diversity and Direct Sequence Spread Spectrum CRDSA,PD-DS-CRDSA)方法。该方法在传统无线网络竞争解决分集时隙ALOHA(Contention Resolution Diversity Slotted ALOHA,CRDSA)算法的基础上,通过采用多副本技术和连续干扰消除技术提高数据包成功解码率,同时引入功率分集和直接序列扩频技术,在一定程度上消除了传统CRDSA算法容易出现的“环路”问题。实验仿真结果表明,该方法在提高VDE-SAT随机接入的峰值吞吐量,延长线性工作区和降低数据包碰撞率等方面有较好表现。展开更多
We propose a nonparametric change point estimator in the distributions of a sequence of independent observations in terms of the test statistics given by Huˇskov′a and Meintanis(2006) that are based on weighted empi...We propose a nonparametric change point estimator in the distributions of a sequence of independent observations in terms of the test statistics given by Huˇskov′a and Meintanis(2006) that are based on weighted empirical characteristic functions. The weight function ω(t; a) under consideration includes the two weight functions from Huˇskov′a and Meintanis(2006) plus the weight function used by Matteson and James(2014),where a is a tuning parameter. Under the local alternative hypothesis, we establish the consistency, convergence rate, and asymptotic distribution of this change point estimator which is the maxima of a two-side Brownian motion with a drift. Since the performance of the change point estimator depends on a in use, we thus propose an algorithm for choosing an appropriate value of a, denoted by a_s which is also justified. Our simulation study shows that the change point estimate obtained by using a_s has a satisfactory performance. We also apply our method to a real dataset.展开更多
文摘Wireless Body Area Networks(WBANs) are expected to achieve high reliable communications among a large number of sensors.The outage probability can be used to measure the reliability of the WBAN.In this paper,we optimize the outage probability with the harvested energy as constraints.Firstly,the optimal transmit power of the sensor is obtained while considering a single link between an access point(AP) located on the waist and a sensor attached on the wrist over the Rayleigh fading channel.Secondly,an optimization problem is formed to minimize the outage probability.Finally,we convert the non-convex optimization problem into convex solved by the Lagrange multiplier method.Simulations show that the optimization problem is solvable.The outage probability is optimized by performing power allocation at the sensor.And our proposed algorithm achieves minimizing the outage probability when the sensor uses energy harvesting.We also demonstrate that the average outage probability is reduced with the increase of the harvested energy.
基金Supported by NNSF of China(Key International Cooperative Project No.60010121219)
文摘Using state assignment to minimize power dissipation and area for finite state ma-chines is computationally hard. Most of published results show that the reduction of switchingactivity often trades with area penalty. In this paper, a new approach is proposed. Experimentalresults show a significant reduction of switching activity without area penalty compared withprevious publications.
基金Supported by the Key Project of Chinese Ministry of Education(No.106042)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry(2007[24])
文摘This paper proposes a novel mapping scheme for bit-interleaved coded modulation with iterative decoding(BICM-ID).The symbol mapping is composed of two QPSK with different radiuses and phases,called cross equalization-8PSK-quasi-semi set partitioning(CE-8PSK-Quasi-SSP).Providing the same average power,the proposed scheme can increase the minimum squared Euclidean distance(MSED)and then improve the receiving performance of BICM-ID compared with conventional symbol mapping schemes.Simultaneously,a modified iteration decoding algorithm is proposed in this paper.In the process of iteration decoding,different proportion of the extrinsic information to the systematic observations results in distinct decoding performance.At high SNR(4~9dB),the observation information plays a more important role than the extrinsic information.Simulation results show that the proportion set at 1.2 is more suitable for the novel mapping in BICM-ID.When the BER is 10^(-4),more than 0.9dB coding gain over Rayleigh channels can be achieved for the improved mapping and decoding scheme.
文摘甚高频数据交换-卫星部分(VHF Data Exchange-Satellite,VDE-SAT)是下一代海事通讯系统甚高频数据交换系统(VHF Data Exchange System,VDES)的关键组成部分,用于实现航海船站与海事卫星以及航海船站间的相互通信和数据传输,其链路层接入性能对于VDES的实际应用效果有着重要影响。针对当前实际应用中航海船站随机接入VDES系统容易出现峰值吞吐量较低和线性工作区较短的问题,该文在深入分析国际电信联盟制定的ITU-R M.2092标准规范和航海船站接入VDE-SAT的技术特性,以及现有无线网络随机接入协议的基础上,提出一种适用于VDE-SAT的基于功率分集和直接序列扩频的竞争解决分集时隙ALOHA(Power Diversity and Direct Sequence Spread Spectrum CRDSA,PD-DS-CRDSA)方法。该方法在传统无线网络竞争解决分集时隙ALOHA(Contention Resolution Diversity Slotted ALOHA,CRDSA)算法的基础上,通过采用多副本技术和连续干扰消除技术提高数据包成功解码率,同时引入功率分集和直接序列扩频技术,在一定程度上消除了传统CRDSA算法容易出现的“环路”问题。实验仿真结果表明,该方法在提高VDE-SAT随机接入的峰值吞吐量,延长线性工作区和降低数据包碰撞率等方面有较好表现。
基金supported by Natural Sciences and the Engineering Research Council of Canada (Grant No. 105557-2012)National Natural Science Foundation for Young Scientists of China (Grant No. 11201108)+1 种基金the National Statistical Research Plan Project (Grant No. 2012LZ009)the Humanities and Social Sciences Project from Ministry of Education of China (Grant No. 12YJC910007)
文摘We propose a nonparametric change point estimator in the distributions of a sequence of independent observations in terms of the test statistics given by Huˇskov′a and Meintanis(2006) that are based on weighted empirical characteristic functions. The weight function ω(t; a) under consideration includes the two weight functions from Huˇskov′a and Meintanis(2006) plus the weight function used by Matteson and James(2014),where a is a tuning parameter. Under the local alternative hypothesis, we establish the consistency, convergence rate, and asymptotic distribution of this change point estimator which is the maxima of a two-side Brownian motion with a drift. Since the performance of the change point estimator depends on a in use, we thus propose an algorithm for choosing an appropriate value of a, denoted by a_s which is also justified. Our simulation study shows that the change point estimate obtained by using a_s has a satisfactory performance. We also apply our method to a real dataset.