This paper suggests a new model for the transmission of Transmission Control Protocol (TCP) traffic over IEEE 802.11 using the new features of IEEE 802.11ac. The paper examines the first step in this direction and as ...This paper suggests a new model for the transmission of Transmission Control Protocol (TCP) traffic over IEEE 802.11 using the new features of IEEE 802.11ac. The paper examines the first step in this direction and as such we first consider a single TCP connection, which is typical in a home environment. We show that when the IEEE 802.11ac MAC is aware of QoS TCP traffic, using Reverse Direction improves the TCP Goodput in tens of percentages compared to the traditional contention based channel access. In an error-free channel this improvement is 20% while in an error-prone channel the improvement reaches 60% also using blind retransmission of frames. In our operation modes we also assume the use in Two-Level aggregation scheme, the Automatic Repeat-Request (ARQ) protocol of the IEEE 802.11ac MAC layer, the data rates and the four Access Categories defined in this standard.展开更多
利用多路径传输协议,多宿主主机可以通过多条路径并行传输数据,从而有效提高系统的吞吐率和鲁棒性.但是由于不同路径在带宽、延迟和丢包率等方面存在差异,接收端必须缓存大量乱序到达的分组.数学分析表明,减少接收端的缓存开销有两条途...利用多路径传输协议,多宿主主机可以通过多条路径并行传输数据,从而有效提高系统的吞吐率和鲁棒性.但是由于不同路径在带宽、延迟和丢包率等方面存在差异,接收端必须缓存大量乱序到达的分组.数学分析表明,减少接收端的缓存开销有两条途径:一是最小化每条路径的发送队列中积压分组的数量,二是降低分组发送速率.由前者,提出依据每条路径的空闲发送窗口大小进行分组调度的算法SOD(Scheduling On Demand);由后者,提出利用窗口通告机制限制分组发送速率的流控方法.模拟实验结果表明:与现有算法相比,SOD的缓存开销最小;在接收端进行流控限制的情况下,SOD的吞吐率最大,并且在不同实验场景中性能表现稳定.展开更多
为缓解基站的视频流量过载,本文针对时延敏感的实时视频业务,设计一种D2D协作视频多播传输方案。该方案采用可伸缩视频编码(Scalable Video Coding, SVC)对视频流进行编码处理,利用SVC流的分层结构特征来应对多播信道间的差异性。在SVC...为缓解基站的视频流量过载,本文针对时延敏感的实时视频业务,设计一种D2D协作视频多播传输方案。该方案采用可伸缩视频编码(Scalable Video Coding, SVC)对视频流进行编码处理,利用SVC流的分层结构特征来应对多播信道间的差异性。在SVC编码的基础上,为了改善用户观看体验及提升用户所接收的视频质量,所提出的协作式视频传输方案引入有效吞吐量这一概念,在一定时延约束下,根据信道反馈信息灵活地对不同信道上的不同SVC视频层进行码率调整。仿真结果表明,所提出的方案能够有效地减小端到端时延,有效丢失率,提高有效吞吐量。展开更多
In this paper, a new selective discarding policy called double threshold based early meassage(DTEMD) policy is present. In the DTEMD policy, two thresholds are defined through which the system can adapt to the curren...In this paper, a new selective discarding policy called double threshold based early meassage(DTEMD) policy is present. In the DTEMD policy, two thresholds are defined through which the system can adapt to the current load without changing its operation modes too often as EMD [1] policy does. Moreover the policy gets high utility of the buffer and so improves the system performance. By adopting a new performance measure “goodput”, analysis results show a remarkable performance improvement is obtained when the improved discarding policy is applied.展开更多
针对多路径并发传输流传输控制协议在实际应用中,因数据乱序造成有效吞吐量远低于各路径的有效带宽总和的问题,提出一种多路径并行传输系统有效吞吐量的优化方法 SCTP-CDD(controlling the difference of delay)。该方法由基于卡尔曼滤...针对多路径并发传输流传输控制协议在实际应用中,因数据乱序造成有效吞吐量远低于各路径的有效带宽总和的问题,提出一种多路径并行传输系统有效吞吐量的优化方法 SCTP-CDD(controlling the difference of delay)。该方法由基于卡尔曼滤波的时延估计和基于时延差控制的拥塞控制算法两部分组成,能够有效减少数据包乱序现象,提高传输系统的吞吐性能。利用NS-2仿真软件对所提方法的性能进行仿真验证。展开更多
This paper proposes a methodology for calculating the energy consumed by a Wireless Sensor Network as well as its throughput under the effect of a jamming node modelling interference to account for collisions and retr...This paper proposes a methodology for calculating the energy consumed by a Wireless Sensor Network as well as its throughput under the effect of a jamming node modelling interference to account for collisions and retransmissions. Accordingly, the proposed methodology takes into consideration retransmissions and data dropped due to interference and collisions simultaneously. Simulations are conducted using OPNET to model various scenarios utilizing off-the-shelf wireless communication standards, namely ZigBee, Wi-Fi and Low Power Wi-Fi. A figure of merit is developed to offer more representative results for applications with different requirements. In achieving different requirements for a given application, there is a clear trade-off between energy consumption and throughput.展开更多
为了最大化正交频分复用(orthogonal frequency division multiplexing,OFDM)无线通信系统中非实时业务的有效吞吐量,提出了一种子载波与数据包长度的联合分配(joint sub-carrier and packet size allocation,JSPSA)策略。该策略较以往...为了最大化正交频分复用(orthogonal frequency division multiplexing,OFDM)无线通信系统中非实时业务的有效吞吐量,提出了一种子载波与数据包长度的联合分配(joint sub-carrier and packet size allocation,JSPSA)策略。该策略较以往的子载波分配或数据包长度优化策略,有更大的优化自由度。基于JSPSA策略,详细分析平坦衰落信道下联合分配算法有效吞吐量函数的单调特征,证明该函数为单峰函数。利用频率选择性信道与平坦衰落信道下有效吞吐量函数单调性特征的相似性,通过引入一种新的等效信道增益,提出了一种频率选择性信道下的JSPSA算法。仿真结果表明,该算法的有效吞吐量接近于JSPSA策略下最优的枚举法,与已有的贪婪比特分配、等误比特率功率分配(greedy algorithm bit allocation/equal bit error ratio power allocation,GABA_EBPA)算法相当,而复杂度却大幅度降低,在复杂度和性能之间取得了较好的折中。展开更多
文摘This paper suggests a new model for the transmission of Transmission Control Protocol (TCP) traffic over IEEE 802.11 using the new features of IEEE 802.11ac. The paper examines the first step in this direction and as such we first consider a single TCP connection, which is typical in a home environment. We show that when the IEEE 802.11ac MAC is aware of QoS TCP traffic, using Reverse Direction improves the TCP Goodput in tens of percentages compared to the traditional contention based channel access. In an error-free channel this improvement is 20% while in an error-prone channel the improvement reaches 60% also using blind retransmission of frames. In our operation modes we also assume the use in Two-Level aggregation scheme, the Automatic Repeat-Request (ARQ) protocol of the IEEE 802.11ac MAC layer, the data rates and the four Access Categories defined in this standard.
文摘利用多路径传输协议,多宿主主机可以通过多条路径并行传输数据,从而有效提高系统的吞吐率和鲁棒性.但是由于不同路径在带宽、延迟和丢包率等方面存在差异,接收端必须缓存大量乱序到达的分组.数学分析表明,减少接收端的缓存开销有两条途径:一是最小化每条路径的发送队列中积压分组的数量,二是降低分组发送速率.由前者,提出依据每条路径的空闲发送窗口大小进行分组调度的算法SOD(Scheduling On Demand);由后者,提出利用窗口通告机制限制分组发送速率的流控方法.模拟实验结果表明:与现有算法相比,SOD的缓存开销最小;在接收端进行流控限制的情况下,SOD的吞吐率最大,并且在不同实验场景中性能表现稳定.
文摘为缓解基站的视频流量过载,本文针对时延敏感的实时视频业务,设计一种D2D协作视频多播传输方案。该方案采用可伸缩视频编码(Scalable Video Coding, SVC)对视频流进行编码处理,利用SVC流的分层结构特征来应对多播信道间的差异性。在SVC编码的基础上,为了改善用户观看体验及提升用户所接收的视频质量,所提出的协作式视频传输方案引入有效吞吐量这一概念,在一定时延约束下,根据信道反馈信息灵活地对不同信道上的不同SVC视频层进行码率调整。仿真结果表明,所提出的方案能够有效地减小端到端时延,有效丢失率,提高有效吞吐量。
文摘In this paper, a new selective discarding policy called double threshold based early meassage(DTEMD) policy is present. In the DTEMD policy, two thresholds are defined through which the system can adapt to the current load without changing its operation modes too often as EMD [1] policy does. Moreover the policy gets high utility of the buffer and so improves the system performance. By adopting a new performance measure “goodput”, analysis results show a remarkable performance improvement is obtained when the improved discarding policy is applied.
文摘针对多路径并发传输流传输控制协议在实际应用中,因数据乱序造成有效吞吐量远低于各路径的有效带宽总和的问题,提出一种多路径并行传输系统有效吞吐量的优化方法 SCTP-CDD(controlling the difference of delay)。该方法由基于卡尔曼滤波的时延估计和基于时延差控制的拥塞控制算法两部分组成,能够有效减少数据包乱序现象,提高传输系统的吞吐性能。利用NS-2仿真软件对所提方法的性能进行仿真验证。
文摘This paper proposes a methodology for calculating the energy consumed by a Wireless Sensor Network as well as its throughput under the effect of a jamming node modelling interference to account for collisions and retransmissions. Accordingly, the proposed methodology takes into consideration retransmissions and data dropped due to interference and collisions simultaneously. Simulations are conducted using OPNET to model various scenarios utilizing off-the-shelf wireless communication standards, namely ZigBee, Wi-Fi and Low Power Wi-Fi. A figure of merit is developed to offer more representative results for applications with different requirements. In achieving different requirements for a given application, there is a clear trade-off between energy consumption and throughput.
文摘为了最大化正交频分复用(orthogonal frequency division multiplexing,OFDM)无线通信系统中非实时业务的有效吞吐量,提出了一种子载波与数据包长度的联合分配(joint sub-carrier and packet size allocation,JSPSA)策略。该策略较以往的子载波分配或数据包长度优化策略,有更大的优化自由度。基于JSPSA策略,详细分析平坦衰落信道下联合分配算法有效吞吐量函数的单调特征,证明该函数为单峰函数。利用频率选择性信道与平坦衰落信道下有效吞吐量函数单调性特征的相似性,通过引入一种新的等效信道增益,提出了一种频率选择性信道下的JSPSA算法。仿真结果表明,该算法的有效吞吐量接近于JSPSA策略下最优的枚举法,与已有的贪婪比特分配、等误比特率功率分配(greedy algorithm bit allocation/equal bit error ratio power allocation,GABA_EBPA)算法相当,而复杂度却大幅度降低,在复杂度和性能之间取得了较好的折中。
