An experimental study of web transport protocols in cellular networks

HTTP and TCP have been the backbone of web transport for decades. There have been numerous enhancements and modifications to both of these protocols. HTTP and TCP were developed for traditional packet networks existing since 1990's. Today, however, wired network parameters such as bandwidth and delay have significantly improved all over the world. However, cellular data networks (GPRS, HSPA) still experience bandwidth and delay issues, which affect the performance of these protocols. HTTP and TCP protocols can be optimized for today's network conditions and end-user requirements, such as accelerated page loading, low latency and better network utilization. Through the course of this work, we measure the improvements in using the SPDY protocol in comparison to HTTP. We measure the impact of header compression, number of parallel TCP connection per domain, and multiplexing of streams. From the TCP perspective, we analyze the impact of higher initial congestion windows. Some of the interesting findings are discussed, comparing various initial congestion window values. All of these experiments are conducted over live GPRS, HSPA and LTE networks. We study the challenges of moving from HTTP to alternative protocols. We also discuss the ways to improve the mobile web browsing by introducing and refining the existing schemes such as DNS pre-fetching, radio transition delays, smart use of IP versions, reduction of TLS negotiation delays, and intelligent allocation of TCP connections in HTTP. Our studies reveal that low bandwidth networks such as GPRS benefits from header compression, whereas the HSPA and LTE networks benefit from multiplexing as it saves the time for establishing new TCP connections. The advantage of higher TCP initial congestion window is seen only in networks with high band width and high latency

Experimentation with Wireless Broadband Traffic Behaviour in WiBrA Project

This experimental study analyzes the effects of larger TCP initial window on competing interactive media and Web traffic in a larger number of cellular access configurations. In addition, we analyze the effect of shorter initial RTO on TCP performance in cellular access configurations. Both simulation and real network experiments were conducted. The initial window of ten segments reduces TCP elapsed times when the number of flows is small enough, however, with large number of flows it introduces losses that require TCP timeout. The initial RTO change from three to one second improves elapsed time in limited number of configurations, but in other cellular configurations spurious timeouts trigger almost alway during TCP three-way handshake due to the lower timeout