An Experimental Testbed for Evaluating End-to-End TCP Performance Over Wired-to-Wireless Paths

Research into the performance issues of TCP over wireless networks has been the focus of much attention in recent years. Specifically, many homes and offices are now fully equipped with WLAN technologies enabling users and devices to connect to the Internet that predominantly run over TCP for reliable service delivery. It is therefore a common scenario today for TCP segments originating from a TCP server in the Internet to traverse a wireless link in the last-hop portion of the connection on its way to a wireless TCP client. We present an experimental testbed that allows researchers to experiment with real TCP implementations over a real-world last-hop IEEE 802.11 WLAN, capturing the true end-to-end behaviour of TCP connections over an emulated Internet. Also, the results obtained from the testbed allowed us to establish the distribution of 802.11 frame losses in a real-world WLAN, which may be insightful to research in the area of packet-loss control techniques such as erasure control coding. The testbed and our initial results are a step forward in making TCP more robust for future wireless environments.