General
on-demand PDCH allocation as a new PSET (not for individual MS support), can be
performed only in the BCCH frequency band if the parameter MBCRAC is set to 0
(default value). To allow general on demand allocation of PDCHs in other bands
in a cell MBCRAC must
be set to 1 or 2.
Extension
of an already existing on-demand PSET is however generally allowed regardless
of the MBCRAC setting.
The
maximum number of on-demand PDCHs per channel group can be limited by the
parameter ODPDCHLIMIT.
At
allocation of on-demand PDCHs, the requested number of channels (or as many as
available and allowed) are selected within the allowed frequency band(s) and
subcell(s) according to the following algorithm:
1
In the case of adding PDCHs to a PSET, then select the TCHGRP where the other
PDCHs in the PSET are located. Then proceed to step 10.
2
Among all TCHGRPs, select the TCHGRPs that have the best idle rank value for
E-TCH.
3
Among these TCHGRPs, select the TCHGRPs that have the best idle rank value for
G-TCH.
4
Among these TCHGRPs, select the TCHGRPs that have the best idle rank value for
B-TCH.
5
Among these select the TCHGRP(s) that fulfils the operator chosen strategy
regarding non hopping TCH on the BCCH frequency, according to parameter CSPSALLOC.
6
If the function Idle Channel Measurements is active, select among these TCHGRPs
the TCHGRPs with the lowest interference level. (This refers to the channel
with the highest interference level within the TCHGRP.)
7
If frequency hopping is used, select among these TCHGRPs the TCHGRPs hopping
over as many frequencies as possible.
8
Among these TCHGRPs select ones in the non BCCH frequency band first, and the
BCCH band as second choice if the prerequisites mentioned above will admit
this.
9
If Packet Data in Overlaid subcell is used, select among these TCHGRPs the
TCHGRPs in the preferred subcell according to the parameter SCALLOC.
10
Among these TCHGRPs, select the first found TCHGRP and allocate as many PDCHs
as requested (or as many as possible and allowed according to the parameter ODPDCHLIMIT, if less).