The Research of TCP Congestion Control Mechanisms in Satallite Networks
|School||Harbin Institute of Technology|
|Course||Computer Science and Technology|
|Keywords||congestion control satellite network long propagation delays high bit error rates|
With the development of the broadband satellite network, the satellite communication industry has entered a new round of rapid growth since the end of last century. The broadband satellite network faces enormous opportunities and challenges because there are many great investments in broadband satellite communication systems being developed or about to launch. On the one hand, it will provide highly competitive broadcast/multicast services, services for the areas that wired networks perform poorly or can not reach, backup emergent channels for terrestrial fiber backbone network and services for military networks; on the other hand, classic TCP congestion control schemes perform poorly in satellite networks due to high link loss rate and long propagation delays.We adopt the broadband satellite network as application background. Considering the characteristics of the broadband satellite network, a new congestion control scheme called TCPCA is introduced. Firstly, the Casablanca discriminator is adopted in receiver to classify wireless losses from congestion losses to solve the problem of high link error rate. Secondly, the design and realization procedure of the transmitter and receiver are illustrated in detail. The queue management of routers has also been covered. In order to alleviate the long retransmission intervals brought by long propagation delays; bulk retransmissions are introduced to retransmit the loss packets in time. Since long propagation delays make the network need more time to recover, an intelligent congestion window adjustment strategy is adopted to reduce the unnecessary reduction of congestion window due to wireless losses leading to the decrease of throughputs. Finally, we analyze the performance of TCPCA by theoretical and experimental approach. Under the same network environment, NS2 simulations show that TCPCA outperforms other TCP schemes in terms of throughput. It also provides a fair share of network resources while retaining friendliness to other TCP variants.