Satellite networks have been deployed with success by several companies in order to allow global broadband access to highly mobile nodes. It is well known that the standard transport protocol, TCP, is not well suited for data transport over satellite links that are characterized by a relatively high bit error rate (BER) and a long propagation delay. Links characterized by high BER suffers of dramatic drops in term of goodput because of the congestion control algorithm employed by TCP Reno which blindly halves the congestion window (cwnd) when 3 duplicate acknowledgment are received inferring a congestion episode. This heuristic leds to undue cwnd reductions in the presence of lossy links where the duplicate acknowledgment are likely to be due to corruption of data packets.
We will develop and test a modified TCP congestion control scheme based on TCP Westwood+ and customized for satellite networks (TCP Westwood Sat - TCPWSat). The novelty of our approach is that we adapt the cwnd to the current end-to-end estimated bandwidth instead of blindly halving it. It has been reported in previous literature that TCP Westwood+ outperforms TCP Reno and other variants when wireless links are used. We will test our protocol in a split scenario where the standard TCP NewReno congestion control is used in the terrestrial segment and TCPWSat is used in the satellite segment. In order to compare the performances of our protocol with other solutions we will use the network simulator 2.
The key technical performance parameters for congestion control algorithms evaluation are the following: - Throughput measured in bit per second (bps) is evaluated as the ratio between the data sent in a period (in bits) and the duration of the period (in seconds). - Goodput measured in bit per second (bps) is the ratio between the data sent in a period without counting the retransimitted bytes and the duration of the period (in seconds). - Packet retransmission rate is measured as the ratio of retransmitted packets and total packets sent. - Fairness. It is the performance parameter that evaluate how a protocol is able to fairly distribute the bandwidth between each flow. The Jain Fairness Index evaluates the fairness of a protocol based on throughput obtained by each flow sharing a bottleneck. The maximum value for the index is 1 which infers that each flow obtains the
We will compare the most important involved in TCP congestion control
Satellite networks have been deployed with success by several companies in order to allow global broadband access to highly mobile nodes. It is well known that the standard transport protocol, TCP, is not well suited for data transport over satellite links that are characterized by a relatively high bit error rate (BER) and a long propagation delay. Links characterized by high BER suffers of dramatic drops in term of goodput because of the congestion control algorithm employed by TCP Reno which blindly halves the congestion window (cwnd) when 3 duplicate acknowledgment are received inferring a congestion episode. This heuristic leds to undue cwnd reductions in the presence of lossy links where the duplicate acknowledgment are likely to be due to corruption of data packets.
We will develop and test a modified TCP congestion control scheme based on TCP Westwood+ and customized for satellite networks (TCP Westwood Sat - TCPWSat). The novelty of our approach is that we adapt the cwnd to the current end-to-end estimated bandwidth instead of blindly halving it. It has been reported in previous literature that TCP Westwood+ outperforms TCP Reno and other variants when wireless links are used. We will test our protocol in a split scenario where the standard TCP NewReno congestion control is used in the terrestrial segment and TCPWSat is used in the satellite segment. In order to compare the performances of our protocol with other solutions we will use the network simulator 2.
The key technical performance parameters for congestion control algorithms evaluation are the following: - Throughput measured in bit per second (bps) is evaluated as the ratio between the data sent in a period (in bits) and the duration of the period (in seconds). - Goodput measured in bit per second (bps) is the ratio between the data sent in a period without counting the retransimitted bytes and the duration of the period (in seconds). - Packet retransmission rate is measured as the ratio of retransmitted packets and total packets sent. - Fairness. It is the performance parameter that evaluate how a protocol is able to fairly distribute the bandwidth between each flow. The Jain Fairness Index evaluates the fairness of a protocol based on throughput obtained by each flow sharing a bottleneck. The maximum value for the index is 1 which infers that each flow obtains the
We will compare the most important involved in TCP congestion control