A TCP Congestion Control Method for Real-Time Communication Based on Channel Occupancy of a Wireless LAN

The demand for real-time communication over wireless LANs is increasing. In the infrastructure mode of IEEE 802.11, wireless terminals, or stations (STAs), share one access point (AP). Since TCP congestion control increases the congestion window size until packet loss occurs, TCP communication takes excessive bandwidth from other communications. Then, TCP communication affect the communication quality of the other STAs which share the same AP. Especially, the communication quality for real-time applications such as video streaming becomes worse. In order to solve this problem, our method estimates the channel occupancy of the wireless LAN and adjusts TCP window size so as not to affect the other communications. When an STA simultaneously makes a real-time UDP communication and a background TCP communication, the proposed method controls the window size without taking bandwidth from the UDP communication. We have evaluated the proposed method by computer simulation experiments and show that the proposed method makes it possible to improve the communication quality of the real- time UDP communication.