Performance of Advanced Hybrid Link Adaptation Algorithms in Mobile Radio Channel
Vladimír Wieser · Brno University of Technology Digital Library (Brno University of Technology) · 2008
Abstract. The fast power adaptation is essential for WCDMA based mobile radio networks, as 3G UMTS. Al-though the first version of UMTS has been released in 1999 (Release 99) evolution was not finished yet. Quality of Service (QoS) and user data rate (e.g. HSDPA and HSUPA) are continuously increasing from release to re-lease. Even though link adaptation frequency (1500 times per second) seems to be enough to span accidental fadings of mobile radio channel, used link adaptation algorithm is based on non-actual information about mobile radio chan-nel state, which causes transmitter reaction delay to the actual channel state. Usage of appropriate prediction method to estimate near future channel state seems to be a valuable step to improve hybrid link adaptation algorithm. In this article we have described and simulated the new SIR-slot based advanced link adaptation algorithms. Algo-rithms were designed to increase efficiency of data trans-mission among a user equipment and base stations (uplink) for different simulation environments (pedestrian channel with mobile subscriber speed 5 km/h, 15 km/h and vehicu-lar channel with speed 45 km/h). Keywords Next generation mobile networks, link adaptation algorithm, prediction methods, uplink data transmis-sion efficiency, hybrid adaptation.