12.9 Global Power Control Parameters

3GPP44.060General Packet Radio Service (GPRS)Mobile Station (MS) - Base Station System (BSS) interfaceRadio Link Control / Medium Access Control (RLC/MAC) protocolRelease 17TS

The Global Power Control Parameters information element contains parameters the mobile station shall use to determine its TX power level. When provided, the MS shall use this information from the most recently received message.

Table 12.9.1: Global Power Control Parameters information elements

< Global Power Control Parameters IE > ::=

< ALPHA : bit (4) >

< T_AVG_W : bit (5) >

< T_AVG_T : bit (5) >

< Pb : bit (4) >

< PC_MEAS_CHAN : bit (1) >

0 — The value ‘1’ was allocated in an earlier version of the protocol and shall not be used.

< N_AVG_I : bit (4) > ;

Table 12.9.2: Global Power Control Parameters information element details

ALPHA (4 bit field)
This field is the binary representation of the parameter  for MS output power control in units of 0.1, see 3GPP TS 45.008.
Range: 0 to 10. The ALPHA power control parameter field is coded according to the following table:

bit
4 3 2 1
0 0 0 0 a = 0.0
0 0 0 1 a = 0.1
0 0 1 0 a = 0.2
: :
1 0 0 1 a = 0.9
1 0 1 0 a = 1.0
All other values are reserved in this version of the protocol and shall be interpreted by the mobile station as  = 1.0.

T_AVG_W (5 bit field)
The T_AVG_W parameter is a signal strength filter period for power control in packet idle mode. 2(k/2) / 6 multiframes, k = 0, 1, 2, … 25 (see 3GPP TS 45.008). Values greater than 25 shall be interpreted as 25 by the mobile station.

T_AVG_T (5 bit field)
The T_AVG_T parameter is a signal strength filter period for power control in packet transfer mode. 2(k/2) / 6 multiframes, k = 0, 1, 2, …, 25 (see 3GPP TS 45.008). Values greater than 25 shall be interpreted as 25 by the mobile station.

Pb (4 bit field)
The Pb parameter is a power reduction value used by the BTS on PBCCH blocks and PCCCH blocks, relative to the output power used on BCCH. The field is coded according to the following table:

bit
4 3 2 1
0 0 0 0 Pb = 0 dB
0 0 0 1 Pb = -2 dB
0 0 1 0 Pb = -4 dB
: :
1 1 1 1 Pb = -30 dB

PC_MEAS_CHAN (1 bit field)
The PC_MEAS_CHAN parameter indicates where the mobile station shall measure the received power level on the downlink for the purpose of the uplink power control.

0 downlink measurements for power control shall be made on BCCH
1 downlink measurements for power control shall be made on PDCH

N_AVG_I (4 bit field)
The N_AVG_I parameter is an interfering signal strength filter constant for power control 2(k/2), k=0, 1, .., 15 (see 3GPP TS 45.008).
Range: 0 to 15