Improving the performance of DCH timing adjustment in 3G networks

Abstract

The main goal of Transport Channel Synchronization is that frames sent by the RNC arrive in time to the Nodes B for transmission over the air interface. The 3GPP specifies a simple Timing Adjustment algorithm that tracks the delay of the Iub link (interface defined between RNC and Node B) by adding or subtracting a constant step. We show that this scheme reacts too slowly under abrupt delay variations and may become unstable in high delay scenarios. This paper proposes an alternative mechanism denominated Proportional Tracking Algorithm (PTA) which ensures stability in any scenario and improves performance compared to the classic one. The stability analysis of PTA is based on control theory and the performance is measured by means of an UTRAN simulator considering realistic traffic conditions in the Iub. © 2008 Springer-Verlag Berlin Heidelberg.