Universal Mobile Telecommunications System (UMTS)
UMTS (Universal Mobile Telecommunications System) is a family of third generation mobile networks designed to offer high bandwidth radio access. UMTS has been specified as an integrated solution for mobile voice and data with wide area coverage. Universally standardised via the Third Generation Partnership Project (3GPP) and using globally harmonised spectrum in paired and unpaired bands, 3G/UMTS in its initial phase offers theoretical bit rates of up to 384 kbps in high mobility situations, rising as high as 2 Mbps in stationary/nomadic user environments.
A significant step towards the UMTS evolution, in the frame of Mobile Broadband realization, is the introduction of the High Speed Packet Access (HSPA) technology (often characterized as 3.5G). HSPA supports both downlink and uplink communication through the High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA) technologies, respectively. HSPA promises the provision of enhanced end-users' experience with a wide range of novel, interactive applications, faster performance and reduced delays. Furthermore, from the operators' prism, HSPA ensures improved network performance, increased capacity and higher coverage. HSPA Evolution (HSPA+) and Long Term Evolution (LTE) of 3G/UMTS systems could bring even more significant improvements.
In UMTS, bandwidth is a limited resource, since the available radio resources can support only a handful high data-rate user simultaneously. Multicast is an efficient method of supporting group communication as it allows the transmission of packets to multiple destinations using fewer network resources. Even if UMTS has not been designed for supporting multicast mechanisms, 3GPP try to support them, mainly through the introduction of the Multimedia Broadcast/Multicast Service (MBMS) framework of UMTS. As the term indicates, MBMS supports both broadcast and multicast service modes.
At this point, LDST works on the analysis and on the improvement of the multicast mechanisms in MBMS through the exploitation of high levels of Radio Resource Management. More specifically, the main research directions of LDST in this field include the investigation of efficient power control and congestion control mechanisms during MBMS multicast transmissions. Additionally, our team investigates the integration of the MBMS and HSPA infrastructures under a joint framework that can ensure the delivery of novel, rich multimedia services in beyond 3G networks.
Our additions for ns-2 simulator can be summarized in the following areas:
- Multicast Routing Functionality in UMTS with Multicast Group Management and User Mobility support
- Multicast Congestion Control Mechanisms
- TCP-Friendly Multicast Congestion Control (TFMCC)
- Pragmatic General Multicast Congestion Control (PGMCC)
Moreover, our team performs extended investigations using the MATLAB tool in the following areas:
- Power Control in MBMS
- Radio Resource Management in MBMS
- Radio Network Planning and Optimization in MBMS
- Efficient MBMS Counting Mechanism