Elastic-TCP: flexible congestion control algorithm to adapt for high-BDP networks

In the last decade, the demand for Internet applications has been increased, which increases the number of data centers across the world. These data centers are usually connected to each other using long-distance and high-speed networks. As known, the Transmission Control Protocol (TCP) is the predominant protocol used to provide such connectivity among these data centers. Unfortunately, the huge bandwidth-delay product (BDP) of these networks hinders TCP from achieving full bandwidth utilization. In order to increase TCP flexibility to adapt for high-BDP networks, we propose a new delay-based and RTT-independent congestion control algorithm (CCA), namely Elastic-TCP. It mainly contributes the novel window-correlated weighting function (WWF) to increase TCP bandwidth utilization over high-BDP networks. Extensive simulation and testbed experiments have been carried out to evaluate the proposed Elastic-TCP by comparing its performance to the commonly used TCPs developed by Microsoft, Linux, and Google. The results show that the proposed Elastic-TCP achieves higher average throughput than the other TCPs, while it maintains the sharing fairness and the loss ratio. Moreover, it is worth noting that the new Elastic-TCP presents lower sensitivity to the variation of buffer size and packet error rate than the other TCPs, which grants high efficiency and stability

Two-level frame aggregation scheme under unreliable channel conditions for IEEE 802.11n WLANs: a survey

Frame Aggregation schemes defined by IEEE 802.11n is the combination of the Aggregate MAC Service Data Unit (A-MSDU) and MAC Protocol Data Unit (A- MPDU). The units are aimed at maximizing Wireless Local Area Networks (WLANs) efficiency at Media Access Control (MAC) level, via the sharing of headers and timing overheads. Moreover, the combination of A-MSDU and A-MPDU is known as Two-level frame aggregation. In spite of their abilities in improving the throughput of MAC Layer, the scheme is still limited by other overheads as a result of aggregation which affects the system performance. Block Acknowledgement (Block ACK) and Frame aggregation were introduced in order to minimize MAC Layer overheads. Still, there are some parameters that affect the aggregation performance, such as aggregate length, sub frame size and channel condition overheads. A-MPDU in other hand minimizes the effect of error condition through sub frame transmission. Therefore, A- MPDU aggregation performances, its limitations, and its promising performances motivated this survey to focus on enhancing Aggregation Mac Protocol Data Unit (eA-MPDU) performance by minimizing the headers overheads of the Two-Level Frame Aggregation Scheme, for the reduction of the channel noise, which by its role will increase the Signal Noise Ratio (SNR) and improve the throughput