EFFICIENT ESTIMATION OF TRANSMISSION POWER APPLIED TO SIMULATION OF CELL BREATHING EFFECT IN CDMA-BASED WIRELESS SYSTEMS

摘要

The so called 3rd Generation wireless communication systems i.e. UMTS or IMT-2000 are expected to dominate the market of cellular communication within the next few years. To distinguish different users these systems do not assign a particular time slot or a particular carrier frequency as it was done in the current systems like GSM. The 3G systems are defined using code division multiple access schemes (CDMA) in order to improve system characteristics. [1, 2] The use of CDMA results in an interference limited system where the transmissions of close-by concurrent communications have direct impact on the capacity and coverage of a cell. [2, 3] Hence, for simulative investigations of such 3G systems the accurate calculation of the current transmission power of each single radio link is required to get reasonable values for capacity as well as for coverage. The first part of this article introduces an efficient approach for estimating the downlink transmission power required even in complex scenarios. The second part describes the application of this approach to the simulative investigation of the mutual dependency of cell coverage, cell capacity and current load [4], the so-called cell-breathing effect.