To boost the performance of 4-ary pulse amplitude modulated(PAM) at low signal-to-noise ratio(SNR), bistable stochastic resonance(BSR) system is introduced into digital communications system and get a reliable signal ...To boost the performance of 4-ary pulse amplitude modulated(PAM) at low signal-to-noise ratio(SNR), bistable stochastic resonance(BSR) system is introduced into digital communications system and get a reliable signal detection scheme. In this paper, we first analyse BSR system for different amplitudes of 4-ary PAM signals. The steadystate of the bistable system will be statistically distinct, and the feasibility of the proposed detection scheme is confirmed. On this basis, we present a detailed study on steady-state transitions of the BSR system, and an explicit expression of the bistable system parameters is derived. By setting the bistable system parameters, bistable system, 4-ary PAM signal, and noise reach the resonance state, and the BSR-based detection scheme is implemented. Moreover, we derive an analytical expression to calculate the symbol error rate(SER) of 4-ary PAM signals with the BSR-based detection under additive white Gaussian noise(AWGN). Finally, the simulation results validate that BSR-based detection scheme can improve the detection performance while efficiently reducing the symbol error rate.展开更多
目前IEEE802.11设备提供了多个不同的传输速率,对动态变化的无线信道选择不同的传输速率可以使系统性能最大化。目前已经有许多速率自适应算法被提出,但是没有一种算法适用于所有环境下的动态变化无线信道,而不同工作环境下需要选择不...目前IEEE802.11设备提供了多个不同的传输速率,对动态变化的无线信道选择不同的传输速率可以使系统性能最大化。目前已经有许多速率自适应算法被提出,但是没有一种算法适用于所有环境下的动态变化无线信道,而不同工作环境下需要选择不同种类的速率自适应算法。概述了不同种类的速率自适应算法,剖析了每种算法影响其性能提高的因素,并对不同种类的算法进行了对比,最后提出了现有速率自适应算法所存在的问题。此外,用NS-2(Network Simulator version 2)仿真软件验证了RTS/CTS(Request-to-Send/Clear-to-Send)信号的作用,它的启用会降低系统频带利用率,但同时也能有效地消除由多个移动终端共用一个AP(access point)引起的碰撞。展开更多
基金supported by the National Natural Science Foundation of China (61631015, 61501354, 61501356, and 61573202)the Fundamental Research Funds of the Ministry of Education (7215433803)+5 种基金the Foundation of State Key Laboratory of Integrated Services Networks (ISN1101002)Higher School Subject Innovation Engineering Plan (B08038)Science and Technology Innovation Team Key Plan of Shaanxi Province (2016KCT-01)The Fundamental Research Funds of the Ministry of Education, China (Grant No. JB160101)The Key Laboratory Foundation of Ministry of Industry and Information Technology (KF20181912)China Postdoctoral Science Foundation (2018M631122)
文摘To boost the performance of 4-ary pulse amplitude modulated(PAM) at low signal-to-noise ratio(SNR), bistable stochastic resonance(BSR) system is introduced into digital communications system and get a reliable signal detection scheme. In this paper, we first analyse BSR system for different amplitudes of 4-ary PAM signals. The steadystate of the bistable system will be statistically distinct, and the feasibility of the proposed detection scheme is confirmed. On this basis, we present a detailed study on steady-state transitions of the BSR system, and an explicit expression of the bistable system parameters is derived. By setting the bistable system parameters, bistable system, 4-ary PAM signal, and noise reach the resonance state, and the BSR-based detection scheme is implemented. Moreover, we derive an analytical expression to calculate the symbol error rate(SER) of 4-ary PAM signals with the BSR-based detection under additive white Gaussian noise(AWGN). Finally, the simulation results validate that BSR-based detection scheme can improve the detection performance while efficiently reducing the symbol error rate.
文摘目前IEEE802.11设备提供了多个不同的传输速率,对动态变化的无线信道选择不同的传输速率可以使系统性能最大化。目前已经有许多速率自适应算法被提出,但是没有一种算法适用于所有环境下的动态变化无线信道,而不同工作环境下需要选择不同种类的速率自适应算法。概述了不同种类的速率自适应算法,剖析了每种算法影响其性能提高的因素,并对不同种类的算法进行了对比,最后提出了现有速率自适应算法所存在的问题。此外,用NS-2(Network Simulator version 2)仿真软件验证了RTS/CTS(Request-to-Send/Clear-to-Send)信号的作用,它的启用会降低系统频带利用率,但同时也能有效地消除由多个移动终端共用一个AP(access point)引起的碰撞。
