1. During handover, MS will access the
target cell with the maximum transmitting power (associated handover command)
allowed by the target cell. But if “MS power prediction after HO” is enable,
then MS will use the optimized power to access the target cell.
2. During intra-cell handover, the
current power will be retained.
3. Power control can be implemented on
TCH carriers only, BCCH carrier is not allowed power control. Because MS needs
to measure the receiving level of BCCH from the adjacent cell. It will be
inaccurate when power control is performed on BCCH.
4. Power control is performed
independently for each channel.
When MS accesses the network via RACH
channel, its transmitting power is the “MS max. TX power level” get from the
system information sent on BCCH. MS send the first message on dedicated channel
also uses the “MS max TX power level” ,this is not under the control of the
system before the power control command which carried on SACCH of SDCCH or TCH.
The implementation procedure is as follows:
1. According to the uplink receiving
level and receiving quality reported by BTS, consider the maximum transmitting
power of MS, BSC calculates the proper transmitting power for the MS.
2. Power control command and the TA value
will be transmitted to MS at layer 1 header carried by each downlink SACCH
block.
3. MS receives the power control command
carried by SACCH header at the end of each SACCH report period, Then MS will
carry out the command in the beginning of next report period. MS can change
power 2dB per 13 frames (60ms) maximum.
4. After MS executed the power control
command, it will set the current power class at the layer 1 message header of
the next uplink SACCH, and transmit it to BTS in the measurement report.
Therefore, it will take 3 measurement report periods for the new power class
(in each power control command) to be available.
Note: Each integral SACCH message block
(measurement report) is composed of 4 burst. A power control implementation
process in whole takes the time of 3 measurement reports.
power control algorithm: HW
I and HW II power control
Power control judgment and the
selection of HWI algorithm or HWII algorithm
Power
control algorithm selected in power control data table
Power
control judgment is controlled by BTS measurement report pre-processing item
which can be selected in handover control data table
MR.
Pre-process (measurement report pre-processing): This switch decide where power
control be processed. If measurement
report pre-processing is “yes”, power control is processed in BTS, and when
setting it “no”, power control is processed in BSC.
Set pre-processing “yes” is to reduce the
signaling load in Abis
interface.
i.e.:
1.If Abis
E1 is in 15:1 mode, it should be set “yes”, otherwise the Abis
capacity for speed is not enough;
2.BTS22C 0110 version should be set “No”;
3.Satellite transmission BTS should be
set “yes”;
4.We should consider few type of BTS has
relationship with HWI algorithm and HWII algorithm, please check the product
manual.