Abstract

2.5 Generation (2.5G) and Third Generation (3G) cellular wireless networks allow mobile Internet access with bearers specifically designed for data communications. However, Internet protocols under-utilize wireless wide area network (WWAN) link resources, mainly due to large round trip times (RTTs) and request-reply protocol patterns. Web browsing is a popular service that suffers significant performance degradation over 2.5G and 3G. In this paper, we review and compare the two main approaches for improving web browsing performance over wireless links: (i) using adequate end-to-end parameters and mechanisms and (ii) interposing a performance enhancing proxy (PEP) between the wireless and wired parts. We conclude that PEPs are currently the only feasible way for significantly optimizing web browsing behavior over 2.5G and 3G. In addition, we evaluate the two main current commercial PEPs over live general packet radio service (GPRS) and universal mobile telecommunications system (UMTS) networks. The results show that PEPs can lead to near-ideal web browsing performance in certain scenarios.

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Session setup delay in Packet Switched Streaming (PSS) services over Third Generation (3G) wireless networks is impacted by Real‐Time Streaming Protocol (RTSP) and Session Description Protocol (SDP) signalling exchange and negotiation, as well as media buffering at the terminal before playback. The paper discusses PSS session setup delay over 3G, and proposes two RTSP and SDP protocol extensions to reduce this delay, namely: RTSP Early Setup and usage of SDP Templates. The rationale behind this proposal is presented, particularly when a Secondary Packed Data Protocol Context (PDP‐Context) is used to support media delivery with Quality of Service (QoS) support. The RTSP Early Setup mechanism facilitates pipelining of RTSP messages and early trigger of Secondary PDP‐Context setup. The SDP Template mechanism proposes using a generic procedure to avoid transmission of frequently used SDP fields. Copyright © 2006 John Wiley & Sons, Ltd.

3G wireless networks such as UMTS are currently providing wide area Internet access. However, the Internet protocols exhibit a suboptimal performance in such scenarios. In this paper we first characterize a live UMTS link from the IP level. We identify critical features such as high latency, delay spikes, high packet loss probability and connectivity gaps, specially when the user moves between cells. Next, we test a set of TCP configurations, demonstrating that TCP performance can be optimized over UMTS by the usage of adequate end-to-end mechanisms and parameter values. Finally, we perform a preliminary study of applications behavior over UMTS.