ABSTRACT
Contents 2.1 Introduction ................................................................................... 48 2.2 Scenario and Model Description ..................................................... 50
2.2.1 Multicell Propagation Model .................................................. 51 2.2.2 System and User Characteristics ............................................. 53
2.3 Scheduling...................................................................................... 54 2.3.1 Round-Robin Scheduler ......................................................... 55 2.3.2 Max C/I Scheduler ................................................................. 55 2.3.3 Proportional Fair Scheduler.................................................... 56 2.3.4 Time-To-Live Scheduler ......................................................... 57
2.4 Analysis of the Default Scenario...................................................... 57 2.4.1 Validation of Cell Selection .................................................... 57 2.4.2 Mixed Traffic Scenario ........................................................... 59
2.5 Mobility: Optimization of Handover Parameters .............................. 62 2.5.1 Handover Threshold .............................................................. 62
2.6 Performance of Different Scheduler Algorithms............................... 68
2.6.1 Specific Scheduler Properties ................................................. 68 2.6.2 Priority Scheduling................................................................. 75 2.6.3 Comparison of Scheduling Algorithms ................................... 78 2.6.4 Consumption of System Resources......................................... 80
2.7 Conclusion ..................................................................................... 82 2.8 Open Issues ................................................................................... 84 Acknowledgments ................................................................................ 85 References ............................................................................................ 85
2.1 Introduction The rapid advances in wireless technologies have brought about a worldwide demand for high quality multimedia applications and services. These will particularly appear in the Internet, as well as in wireless scenarios [1,2]. Real-time services over high speed downlink packet access (HSDPA) is an issue under discussion in 3rd Generation Partnership Project (3GPP) [3,4]. A key improvement of Universal Mobile Telecommunications System (UMTS) has been realized with HSDPA, which has been defined for release 5 of the UMTS standard within 3GPP. HSDPA aims at increasing the systems capacity and the users’ peak throughput from 2 to over 10 Mbps. Its transmission time feedback loop is smaller than that of regular UMTS and the scheduling functionality is no longer in the radio network controller (RNC) but in the Node-B (base station). As a result, the fluctuations in the radio channel fading characteristics can be better tracked. Scheduling of data flows is a key mechanism to provide quality of service (QoS) and optimize resource efficiency. Whereas the former objective is clearly the most important to the user, the latter is essential for the operator.
