ABSTRACT
Contents 7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234 7.2 UTRAN Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
7.2.1 UTRAN Functionalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 7.2.2 UTRAN Interface Functionalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
7.2.2.1 Iu Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 7.2.2.2 Iur Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240 7.2.2.3 Iub Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
7.2.3 Radio Resource Management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241 7.2.3.1 Combining/Splitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241 7.2.3.2 Connection Setup and Release. . . . . . . . . . . . . . . . . . . . . 242
7.2.4 Radio Bearer Allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242 7.2.5 Radio Protocol Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
7.3 UTRAN Protocol Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 7.3.1 HSDPA Protocol Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244 7.3.2 HSUPA Protocol Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 7.3.3 UTRAN MAC Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
7.4 E-UTRAN Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 7.5 UTRAN Design: Iub Link Resource Management Algorithms . . . . . . 252
7.5.1 Joint Iub Link Flow Control Model . . . . . . . . . . . . . . . . . . . . . . . . . . 254 7.6 Air Interface and Iub Parameter Interdependencies . . . . . . . . . . . . . . . . 259
7.6.1 Simulation Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 7.6.2 Performance Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
7.6.3 Adaptive Iub Link Management Algorithm . . . . . . . . . . . . . . . . . . 265 7.6.3.1 Estimating HSDPA Air Interface Average
Throughput . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265 7.6.3.2 Adaptive Iub Bandwidth Allocation . . . . . . . . . . . . . . . . 266
7.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
7.1 Introduction Radio access network (RAN) is one of the key elements of a mobile communication network. The RAN plays a key role in offering multimedia services to users as well as maintaining QoS (quality of service) for different services. The design of RAN parameters is very important in maintaining the appropriate QoS for different services, particularly in a packet-switched wireless network where resource-sharing techniques are applied to maximize network resource utilization and to minimize operating costs. The UMTS (Universal Mobile Telecommunications System) network uses a standard mobile telephone network architecture where various functionalities are grouped and distributed over logical subnetworks that are connected through different logical interfaces. Functionally, all UMTS network elements are grouped within the RAN known as UTRAN (UMTS Terrestrial Radio Access Network) and the core network (CN), which connects the UTRAN to external networks such as PSTNs (public switched telephone networks) and the Internet. Figure 7.1 shows the generic UMTS architecture, depicting the basic reference points and interfaces [1]. The separation of subnetworks allows ease of interconnection and independence of signaling and data transparent networks. Currently, both the legacy WCDMA (Wideband Code Division Multiple Access) network and the HSPA (HighSpeed Packet Access) network share the same CN but have different UTRAN architectures, functions, and resource management algorithms. UMTS networks, which are currently offering both legacy and HSDPA (High-Speed Downlink Packet Access)/HSPA services, have upgraded their UTRAN functionalities based on Release 5/6 or higher 3GPP (3rd Generation Partnership Project) standards. The new standard supports both legacy services as well as advanced packet based HSPA services. Introduction of HSDPA and HSUPA (High-Speed Uplink Packet Access) services have increased the packet-switched traffic volume in the UTRAN and in the CN. The UTRAN architecture is currently evolving toward a high data rate and high QoS network. Recently, the E-UTRAN (Evolved UTRAN) architecture was introduced; it was designed to support advanced packet-switched services using a flat network architecture to accommodate new services as well as to offer high QoS to all services.
