QoS-oriented Admission Control in HSDPA networks

Abstract

Abstract - HSDPA defines a new High Speed Shared Channel (HS-DSCH) which allows for practical speeds up to 10 Mbps [1]. Among all the changes introduced by HSDPA, the most prominent ones regarding QoS are the inclusion of “link adaptation”, “Hybrid ARQ” and the quick “Scheduling” algorithms. In HSDPA the RNC is still the responsible for making the decision of admitting new users but also for handling different kinds of traffics of different users over the same channel. One of the mostly adopted solutions for admitting new users assuring QoS comprises an admission control algorithm based on performance, with the cells power as the limiting resource. This kind of algorithms makes use of a static “guard power offset” for users whose channel conditions worsen in the course of the connection. In this paper, we propose two admission control algorithms that take into account that this guard power varies according to the channel conditions of each user, the number of allowed users, the service and the transmission speed that they require, and the power used by the cell on each TTI (Transmission Time Interval).

The coverage radius of the cell will be divided into three concentric rings, and those users with better channel conditions (the ones nearer to the Node-B) will be assigned with higher priority. Since they will need less power than those farther they will have a better chance on satisfying their needs. Simulation scenario in Matlab shows the behavior of these proposals by comparing how many users are admitted and how many of them are satisfied.