Long-Haul TCP vs. Cascaded TCP

In this work, we investigate the bandwidth and transfer time of long-haul TCP versus cascaded TCP [5]. First, we discuss the models for TCP throughput. For TCP flows in support of bulk data transfer (i.e., long-lived TCP flows), the TCP throughput models have been derived [2, 3]. These models rely on the congestion-avoidance algorithm of TCP. Though these models cannot be applied with short-lived TCP connections, our interest relative to logistical networking is in longer-lived TCP flows anyway, specifically TCP flows that spend significantly more time in the steady-state congestion-avoidance phase rather than the transient slow-start phase. However, in the case where short-lived TCP connections must be modeled, several TCP latency models have been proposed [1, 4] and based on these latency models, the throughput and transfer time of short-lived TCP connections are obtainable. Using the above models, the transfer times for a data file of size S packets can be computed for both long-haul TCP and cascaded TCP. The performance of both systems is compared via their transfer times. One system is said to be preferred if its tranfer time is lower than that of the other. Based on these performance comparisons, we develop a decision model that decides whether to use the cascaded TCP or long-haul TCP

Performance Analysis of Channel-Aware Media Access Control Schemes

This thesis proposes a new Channel-Aware MAC (CA-MAC) protocol that allows more than two simultaneous transmissions to take place within a single wireless collision domain. In this proposed work, Multiple-Input Multiple-Output (MIMO) system is used to achieve higher spectral efficiency. The MIMO-based PHY layer has been adopted to help in controlling the transmission and to avoid any collisions by using weights gains technique on the antenna transmission, and by recovering any possible collisions using ZigZag decoding. In order to develop CA-MAC algorithm, to exploit the full potential of MIMO system, the library of 802.11x standard has been modified. NS-2 based simulations were conducted to study the performance of the proposed system. Detailed analysis and comparisons with current protocols schemes are presented

Data Logistics in Network Computing

In distributed computing environments, performance is often dominated by the time that it takes to move data over a network. In the case of data-centric applications, or Data Grids, this problem of data movement becomes one of the overriding concerns. This talk describes techniques for improving data movement in Grid environments that we refer to as 'logistics.' We demonstrate that by using storage and cooperative forwarding 'in' the network, we can improve end to end throughput in many cases. Our approach offers clear performance benefits for high-bandwidth, high-latency networks. This talk will introduce the Logistical Session Layer (LSL) and provide experimental results from that system