The increasing trend in the mobile air-interface data rates means that the relative contribution of the transport network towards the per-user capacity is becoming very important. Admission, load and handover control can make use of information regarding the Available Bandwidth (ABw) in the transport network, as it could end up being the bottleneck rather than the air interface. This report provides a comparative study of three ABw estimation techniques (TOPP, SLoPS and pathChirp) taking into account the statistical conditions of the ABw, several improvements of pathChirp in terms of accuracy and eficiency, and a performance evaluation of pathChirp under a DifiServ environment. Simulation-based studies show that pathChirp outperforms TOPP and SLoPS, both in terms of accuracy and eficiency. By combining the optimized linear profile with a linear least squares fitting, it is possible to reduce the average relative error from 23.6% to 3.2%. From this work, it is drawn that the use active probing has to be mainly focused on ABw trend detection for load control rather than for real-time adaptive QoS management.
|Effektiv start/slut dato||01/09/2005 → 22/05/2006|
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