QoS guaranteeing during UMTS packet-domain handover

We focus on the problem of guaranteeing real-time service quality during the interRNS handover/relocation in packet-domain/all-IP UMTS. We propose fully seamless SRNS relocation mechanisms for the conversational and streaming services respectively. The multimedia service quality can be guaranteed by packets bicasting in backbone and radio signal macrodiversity. By adapting and extending the data link protocols GTP-U/PDCP/RLC, we synchronize the packet streams in the new and old backbone routes. For the streaming class we propose a new RLC mode called no-sequencing acknowledged RLC, assuring packet lossless delivery and throughput steady during relocation. Our mechanisms are based on existing basic interRNS procedure, and could be easily integrated into it. Synchronous multicast/bicast requires backbone links to be overprovisioned with bandwidth. In multicast-tree mode, the bandwidth overprovision amount of Iu-PS link is the sum of capacities of the neighbor cells. In multicast-on-demand/bicast mode, the bandwidth overprovision amount of Iu-PS link is 2 Mbps. There is no need to overprovision the Iur link bandwidth.