Improving Throughput of Transmission Control Protocol Using Cross Layer Approach

Most of the internet users connect through wireless networks. Major part of internet traffic is carried by Transmission Control Protocol (TCP). It has some design constraints while operated across wireless networks. TCP is the traditional predominant protocol designed for wired networks. To control congestion in the network, TCP used acknowledgment to delivery of packets by the end host. In wired network, packet loss signals congestion in the network. But rather in wireless networks, loss is mainly because of the wireless characteristics such as fading, signal strength etc. When a packet travels across wired and wireless networks, TCP congestion control theory faces problem during handshake between them. This paper focuses on finding this misinterpretation of the losses using cross layer approach. This paper focuses on increasing bandwidth usage by improving TCP throughput in wireless environments using cross layer approach and hence named the proposed system as CRLTCP. TCP misinterprets wireless loss as congestion loss and unnecessarily reduces congestion window size. Using the signal strength and frame error rate, the type of loss is identified and accordingly the response of TCP is modified. The results show that there is a significant improvement in the throughput of proposed TCP upon which bandwidth usage is increased.     

含参量分数阶微分系统的基本分岔分析

本文中,我们讨论了含参量分数阶微分系统的基本分岔,即跨临界分岔、折叠分岔与音叉分岔.首先,根据分数阶Lyapunov方法,讨论了含参量分数阶微分系统的稳定性,并给出了这些基本分岔的相图.其次,根据Taylor展式与隐函数定理,研究了分数阶微分系统的规范形,从而求出这些基本分岔的拓扑规范形.     

Signal strength based routing for power saving in mobile ad hoc networks

The transmission bandwidth between two nodes in mobile ad hoc networks is important in terms of power consumption. However, the bandwidth between two nodes is always treated the same, regardless of what the distance is between the two nodes. If a node equips a GPS device to determine the distance between two nodes, the hardware cost and the power consumption increase. In this paper, we propose using a bandwidth-based power-aware routing protocol with signal detection instead of using GPS devices to determine the distance. In our proposed routing protocol, we use the received signal variation to predict the transmission bandwidth and the lifetime of a link. Accordingly, the possible amount of data that can be transmitted and the remaining power of nodes in the path after data transmission can be predicted. By predicting the possible amount of data that can be transmitted and the remaining power of nodes after data transmission, we can design a bandwidth-based power-aware routing protocol that has power efficiency and that prolongs network lifetime. In our simulation, we compare our proposed routing protocol with two signal-based routing protocols, SSA and ABR, and a power-aware routing protocol, MMBCR, in terms of the throughput, the average transmission bandwidth, the number of rerouting paths, the path lifetime, the power consumed when a byte is transmitted, and the network lifetime (the ratio of active nodes).     

基于RBS 的合作通信网络公平合作策略

针对合作通信网络中基于纳什议价解(NBS)的合作策略存在用户效用分配不公平的问题,同时考虑用户的最大与最小效用,提出了基于Raiffa-Kalai-Smorodinsk议价解(RBS)的合作策略,并建立了用户合作的条件.仿真结果表明,基于RBS的合作策略在保证网络总效用不变的前提下,具有更好的公平性.     

分数阶系统的最优Oustaloup数字实现算法

控制系统通常无法用确定的解析表达式表达,所以需要利用滤波器来近似数字实现分数阶微积分.为此,提出一种新的分数阶系统数字实现算法--最优Oustaloup数字实现算法,通过最优算法寻找滤波器最优参数,在频率段内实现分数阶系统模型的高拟合精度.实例仿真结果表明,该算法在频率响应中的幅频特性及相频特性均优于Oustaloup及其改进算法.     

具有随机通信逻辑的网络控制系统稳定性分析

针对具有带宽约束的网络控制系统,讨论了在随机通信逻辑调度策略下系统的稳定性问题.将基于时倚泊松过程的随机通信逻辑引入系统中,建立了泊松强度与系统估计偏差之间的函数关系.利用随机点过程方法,证明了系统状态的更新时刻具有Markov特性,进而将系统转化为Markov跳变系统.利用随机稳定性理论,得到系统几乎处处稳定和均方渐近稳定的充分条件.仿真算例表明了该调度策略的有效性.     

Numerical inversions of a source term in the FADE with a Dirichlet boundary condition using final observations

This paper deals with an inverse problem of determining a source term in the one-dimensional fractional advection-dispersion equation (FADE) with a Dirichlet boundary condition on a finite domain, using final observations. On the basis of the shifted Grünwald formula, a finite difference scheme for the forward problem of the FADE is given, by means of which the source magnitude depending upon the space variable is reconstructed numerically by applying an optimal perturbation regularization algorithm. Numerical inversions with noisy data are carried out for the unknowns taking three functional forms: polynomials, trigonometric functions and index functions. The reconstruction results show that the inversion algorithm is efficient for the inverse problem of determining source terms in a FADE, and the algorithm is also stable for additional data having random noises.     

Stochastic differential equations driven by a Wiener process and fractional Brownian motion: Convergence in Besov space with respect to a parameter

A stochastic differential equation involving both a Wiener process and fractional Brownian motion, with nonhomogeneous coefficients and random initial condition, is considered. The coefficients and initial condition depend on a parameter. The assumptions on the coefficients and the initial condition supplying continuous dependence of the solution on a parameter, with respect to the Besov space norm, are established.     

Anti-periodic fractional boundary value problems

We study a class of anti-periodic boundary value problems of fractional differential equations. Some existence and uniqueness results are obtained by applying some standard fixed point principles. Several examples are given to illustrate the results.