Overload Control of Best-Effort Traffic in the UTRAN Transport Network

In this work, it is shown that overload of the UTRAN transport network can result in a severe degradation of the end-user throughput and quality of service. In particular, for dedicated transport channels carrying non-guaranteed traffic in the downlink, a loss of more than 50% of the traffic is observed already at quite modest overload levels. To counteract these adverse effects, we propose a method to gracefully regulate transport network overload by temporarily limiting the available transport formats in the UTRAN MAC layer. Results show that the proposed method is capable of delivering both good end-user quality and a low level of losses at times of transport network overload. With the present method, it is therefore possible to relax the admission criteria to the UTRAN transport network, resulting in reduced connection blocking, higher transport network utilization, and better end-user satisfaction.