排序方式: 共有95条查询结果,搜索用时 31 毫秒
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往返时延(RTT)是网络测量中的一个重要测度,是刻画网络性能的重要指标。传统的RTT测量都是基于报文的,需要专门的主动或被动测量平台的支持。提出一种新的 RT T 估计方法,仅使用现有路由器设备提供的流记录,不需要额外的网络测量设施。通过对 TCP 块状流传输特性的分析,分别建立了当套接字缓冲区长度与带宽延迟积BDP相对较小、较大和相近这3种情况下的RTT估计模型。实验结果表明,这些模型都能很好地完成RTT估计。同时,由于在估计当中只使用了流持续时间和总报文两个变量,因此,该方法同样适用于以抽样流记录为输入的环境,能够有效地应用于现有的大规模主干网环境的网络检测与管理。 相似文献
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In this paper,we present the effective distance between T-cell and B-cell in an immune system using Stop and Wait(S/W)Automatic Repeat Request(ARQ).The concentration of the molecules can be increased by increasing the transmitting number of molecules but it may reduce the performance of communication due to higher collision or interference with other molecules.It is also reported in the literature that the concentration of the emitted molecules reduces if the distance from Transmitter(Tx)to Receiver(Rx)increases.Thus,this paper mainly focuses on enhancing the receiver’s capture probability and higher successful complete transmission of the desired molecules by obtaining the effective distance from T-cell to B-cell.In order to find the effective distance,T-cell transmits the molecules 1(Interleukins-2)to B-cell,upon successful reception of molecules 1,antibodies(molecules 2)transmit back to T-cell.Then,the effective distance of an immune system can be obtained after T-cell detects the concentration of the molecules 2 with respect to time.Different schemes of S/W ARQ protocols have implemented in Molecular Communication(MC)but it requires retransmission of duplicate copies due to the lack of addressing an effective distance.Thus,the simulations are performed in MATLAB and the results obtain higher capture probability and also successful complete transmission of the desired molecules. 相似文献
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The wireless network is limited by the transmission medium, and the
transmission process is subject to large interference and jitter. This jitter can cause
sporadic loss and is mistaken for congestion by the congestion control mechanism. The
TCP Westwood protocol (referred to as TCPW) is such that it cannot distinguish between
congestion loss and wireless jitter loss, which makes the congestion mechanism too
sensitive and reduces bandwidth utilization. Based on this, the TCPW protocol is
modified based on the estimate of the Round-Trip Time (referred to as RTT) value-called
TCPW BR. The algorithm uses the measured smooth RTT value and divides the
congestion level according to the weighted average idea to determine congestion loss and
wireless jitter loss. The simulation results show that the TCPW BR algorithm enhances
the wireless network’s ability to judge congestion and random errors. 相似文献
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Google提出了一种基于瓶颈带宽和往返传播时间的拥塞控制算法(bottleneck bandwidth and round-trip propagation time,BBR),可以在网络链路中保持最大传输速率和最小延时。然而一些评估实验表明,BBR算法会导致不同往返时间(round trip time,RTT)的数据流之间存在严重的公平性问题。为了优化这一问题,研究分析了BBR算法探测机制所导致的发送速率与瓶颈带宽不匹配对RTT公平性的影响,提出了一种基于起搏增益模型的优化算法BBR-adaptive(BBR-A)。BBR-A算法不再采用原BBR算法中固定的起搏增益,而是利用RTT与起搏增益的关系,构造一个基于反比例函数的起搏增益调节模型,通过让向上和向下的起搏增益系数相互交错来平衡发送速率,使每个BBR流可以公平地竞争带宽资源。网络模拟器3(network simulator 3,NS3)仿真实验结果表明:BBR-A算法的信道利用率比BBR算法有了小幅提升;在RTT公平性的方面,BBR-A缩小了不同RTT流之间的吞吐量差异,在不同缓冲区和RTT差异下,Jain公平指数至少提高了1.5倍;BBR-A算法明显降低了重传率。因此通过自适应调整起搏增益系数,可以平衡不同数据流之间的发送速率,有效提升BBR算法的RTT公平性。 相似文献
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