Multi-Layer Protocol Tracing in a GPRS Network
Andrei Gurtov
Matti Passoja
Olli Aalto
Mika Raitola
In Proceedings of the IEEE Vehicular Technology Conference (Fall VTC2002), Vancouver, Canada, Sepember 2002.
[Full Text in PDF Format, 236KB]
Abstract
This paper presents a performance evaluation of GPRS accomplished by
combination of measurement at the end hosts and tracing inside the
network. The multi-layer tracing approach allows not only observing, but
also understanding the network performance. With end-to-end measurements
we assess data rates, latency, and buffering experienced by users in a
live GPRS network. Comparing the results to our previous measurements
shows a notable improvement in the network and terminals over past two
years. Mobility tests while driving in the urban environment quantify the
interval, duration and data loss caused by cell reselections. In the test
lab, multi-layer tracing of radio, link and transport protocols gives a
closer picture of GPRS performance. For instance, TCP interacts
inefficiently with resource allocation at the RLC layer and fragmentation
at the LLC layer. Finally, we illustrate delay spikes and data losses
during a cell reselection by tracing of signaling messages during a cell
update and routing area update procedures.