The Transfer Control Protocol (TCP) plays a central role in today’s networks. A vast majority of Internet traffic uses TCP, including most of streaming video.
However, the explosion of wireless access in the last decade has revealed severe limitations in TCP, as typical wireless packet losses of 2% may cause throughput drops reaching 60%.
Although TCP was not designed for a wireless environment, our coding technology enables it to overcome its wireless limitations in the following manner.
TCP was designed to deliver packets in sequence and combat congestion in wired networks. The former goal is accomplished by checking the packet order and requesting the retransmission of missing packets, while the latter is accomplished through halting transmissions when congestion is sensed (backing off).
Combining these two objectives has proved to be arduous in wireless networks. Packet loss, a common occurrence in wireless and mobile networks, causes TCP to halt transmissions due to the sequential delivery constraint. To make things worse, TCP misinterprets the occasional missing packet as congestion, leading to frequent and unnecessary backoff events. This is what causes the all too common buffering circle seen while streaming videos over wireless networks.
Our technology enables TCP to deliver packets sequentially using the wireless connection’s full bandwidth, while still avoiding congestion adequately. This is accomplished through our algorithm’s unique capability of removing state distinctions between packets and injecting small levels of redundancy when required.
Coded TCP was shown to eliminate video buffer overruns (interruptions) over a 25Mbps link even with 20% packet losses — conditions where conventional TCP implementations fail. In addition, Coded TCP has shown up to 2.5x throughput improvements in public WiFi networks.
Our partners at Speedy Packets develop CTCP products.