The Universal Mobile Telecommunication Services (UMTS) network was envisioned to carry a wide range of new services; however, the first UMTS release was not designed to efficiently support multimedia content. In this thesis we analyse several mechanisms, and suggest architectural changes to improve UMTS’s capacity for a subset of the multimedia services; high-bandwidth group services. In our initial work we have suggested how IP multicast protocols can be used in the UMTS network to reduce the required network capacity for group services. This proposal was one of many suggestions for the evolving Multimedia Broadcast/Multicast Service (MBMS) architecture for UMTS. The next technique we have suggested and analysed is a new wireless channel type named the "sticky-channel"; this channel is intended for sparsely populated multicast groups. The sticky-channel is able to stick to mobile multicast members in the boarder area of neighbouring radio cells, thus some base stations does not need to broadcast the multicast data. Consequently, the total number of broadcast channels needed to cover a given area is reduced. There is a marginal reduction of required resources with this technique. In the main part of our work we have studied heterogeneous multihop wireless access for multicast traffic in the UMTS network. In a heterogeneous wireless access network, the wireless resources needed to distribute high-bandwidth group services, can be shared among cooperating network technologies. Mobile terminals with a UMTS interface and an IEEE 802.11 interface are readily available, consequently a heterogeneous network with UMTS and 802.11 links will be easy to deploy. We have described a heterogeneous architecture based on those wireless technologies. In this architecture, the range of a UMTS radio channel is reduced, and local IEEE 802.11-based Mobile Ad Hoc Networks (MANETs) forward the data to users located outside the coverage of the reduced UMTS channel. The wireless resources required to transmit a data packet are proportional to (at least) the square of the distance the packet must travel, thus a reduction in the channel range releases a significant amount of UMTS radio resources. Detailed simulation results showed acceptable service quality when the UMTS broadcast channel range is more than halved. Finally we have studied whether Forward Error Correction (FEC) at the packet-level on multicast flows could improve the performance of the heterogeneous wireless access network. There is a marginal improvement. Most of the protection brought by the FEC code has been used to repair the increased packet-loss introduced by the FEC overhead.
M. Hauge and Ø. Kure, “Multicast in 3G Networks: Employment of Existing IP Multicast Protocols in UMTS,” In Proceedings of the 5th ACM International Workshop on Wireless Mobile Multimedia 2002 (WoWMoM'02), Atlanta, USA, 2002, pp.96-103.
M. Hauge and Ø. Kure, “Sticky Point-to-multipoint Channel for Multicast in UMTS,” In proceedings of the 8th International Conference on Cellular and Intelligent Communications 2003 (CIC'03), Seoul, South Korea, 2003.
M. Hauge and Ø. Kure, “Multicast Service Availability in a Hybrid 3G-cellular and Ad Hoc Network,” In Proceedings of the 1st International Workshop on Wireless Ad-hoc Networks 2004 (IWWAN'04), Oulu, Finland, 2004.
M. Hauge, A. Hafslund, F.Y. Li and Ø. Kure, “Multicast-service Distribution on a Cellular Network Assisted by Local Ad Hoc Networks,” In proceedings of the 3rd Annual Mediterranean Ad Hoc Networking Workshop (Med-Hoc-Net'04), Bodrum, Turkey, 2004, pp.68 - 80.
M. Hauge and Ø. Kure, “A Heterogeneous Cellular and Ad Hoc Network Architecture for Multipoint Streaming: A detailed performance analysis,” In Proceedings of the 3rd International Conference on Mobile Computing and Ubiquitous Networking (ICMU’06), London, UK, 2006. (A version of this paper has been accepted for publication in a special issue of the Information Processing Society of Japan (IPSJ) Journal, featuring selected papers from ICMU 2006.)
M. Hauge and Ø. Kure, “Evaluation of Packet-level FEC with Multicast Streaming for a Heterogeneous 3G-Cellular and Ad Hoc Network,” In Proceedings of the European Symposium on Mobile Media Delivery 2006 (EuMob’06), Alghero, Sardinia, Italy, 2006.
M. Hauge, “Multicast in a Hybrid Cellular and Ad Hoc Network: Specification of an Ad Hoc Routing Protocol with Cellular Assistance,” Research Report no. 334, Department of Informatics, University of Oslo, Norway, March 2006