This Implementation Instruction specifies the implementation of Cell Based Dynamic Halfrate Allocation for BSS R9.1 MD.

This document supports the GSM 900 and the GSM 1800 system.

Dynamic Halfrate Allocation is an optional featurein BSS R9.1 MD.Dynamic Half Rate Allocation function will allow the allocation of speech traffic channels based on the traffic load in the cell. The HR and FR traffic channels in a cell will be allocated according to a threshold. The threshold is represented by the new BSC command parameter CELLOAD in command RLDEC. The parameter is given as a percentage value of the number of all deblocked TCH/Fs in a cell. From this percentage value an absolute threshold value for each cell is calculated. The threshold is defined in by RLDEC in CELLOAD parameter for each cell. For example, if CELLOAD is set to 50 for cell1, which has 30 TCH/Fs the threshold will be 15. Whereas for cell2, which has 40 TCH/Fs the threshold is 20.

The absolute threshold is compared to the number of busy and idle FR channels. When the number of idle channels is above the threshold, FR channel will be allocated. If the number of idle FR channels is below or equal the threshold, HR capable mobiles will be given HR channels and FR channels are reserved for FR mobiles. The allocation of channels based upon the threshold will be done at both call setup and handover into the cell. The feature is applicable for singleslot connections only.

To activate this Cell Based Dynamic Half Rate feature the BSC must be defined with Half Rate TRA Pool. The DT file will enable the BSC to be defined with Half Rate TRA Pool.