Power configuration

Introduction

This document describes how to set the maximum output power transmitted by u-blox cellular modules by means of AT interface. The LTE maximum Tx power can be customized by means of the +UMAXPWR AT command.

The maximum output power transmitted by u-blox cellular modules in all the supported LTE bands complies with the maximum output power values defined in 3GPP TS 36.101 [36.101] and 3GPP TS 36.521-1 [36.521-1].

The LTE technical specifications 3GPP TS 36.101 [36.101] and 3GPP TS 36.521-1 [36.521-1] define that any E-UTRA User Equipment (such as a u-blox cellular module supporting LTE radio access technology) may reduce its maximum output power depending on the modulation being used and the number of Resource Blocks (RB) transmitted in each channel bandwidth during an LTE call, implementing the LTE maximum power reduction (MPR), and also the LTE additional maximum power reduction (A-MPR) upon specific network signaling. By default, u-blox cellular modules implement the LTE MPR and A-MPR, i.e. they reduce the maximum output power during LTE data calls upon applicable conditions.

The module’s maximum output power can also be reduced during any data call in 4G radio access modes by using the +UMAXPWR AT command.

Examples of power configuration AT commands usage are provided in section Power configuration examples.

Maximum RF power customization +UMAXPWR

+UMAXPWR

Modules

LEXI-R10401D-00B LEXI-R10801D-00B

Attributes

Syntax

PIN required

Settings saved

Can be aborted

Response time

Error reference

partial

No

No

No

-

+CME Error

Description

Modifies the module’s maximum output power during any voice or data call in all GSM/GPRS and/or UMTS/HSPA and/or LTE radio access modes.

The command allows user to decrease the value of the maximum transmitted power with respect to the factory-programmed nominal value in the radio access technology supported:

  • The power customization is set in steps of 1 dB.

In the set command at least a parameter must be issued.

See the corresponding module data sheet for the list of bands supported by the product.

Use of this AT command is the responsibility of the user, since a change in the maximum Tx power can violate 3GPP specifications and affect the UE behavior both in real networks and during the certification process. See 3GPP TS 45.005 [45.005], 3GPP TS 51.010-1 [51.010-1], 3GPP TS 25.101 [25.101], 3GPP TS 34.121-1 [34.121-2] and FCC online documentation for further information.

u-blox assumes no responsibility for the inappropriate use of the +UMAXPWR AT command.

Syntax

TypeSyntaxResponseExample

Set

AT+UMAXPWR=[<3G_pwr_red>][,[<2G_pwr_red_850>],[<2G_pwr_red_900>],[<2G_pwr_red_1800>],[<2G_pwr_red_1900>][,<4G_pwr_red>[,[<bitmask1>][,<bitmask2>]]]]

OK

AT+UMAXPWR=13

OK

AT+UMAXPWR=,40,40,0,0

OK

Read

AT+UMAXPWR?

+UMAXPWR: <3G_pwr_red>,<2G_pwr_red_850>,<2G_pwr_red_900>,<2G_pwr_red_1800>,<2G_pwr_red_1900>[,<4G_pwr_red>][,<bitmask1>,<bitmask2>]

OK

+UMAXPWR: 0,0,0,0,0

OK

+UMAXPWR: 16,16,16,16,16

OK

Test

AT+UMAXPWR=?

+UMAXPWR: (list of supported <3G_pwr_red>s),(list of supported <2G_pwr_red_850>s),(list of supported <2G_pwr_red_900>s),(list of supported <2G_pwr_red_1800>s),(list of supported <2G_pwr_red_1900>s)[,(list of supported <4G_pwr_red>s)][,(list of supported <bitmask1>s),(list of supported <bitmask2>s)]

OK

+UMAXPWR: (0-32),(0-48),(0-48),(0-48),(0-48),(0-32),(1-0xffffffff),(1-0x000007ff)

OK

Defined values

Parameter

Type

Description

<3G_pwr_red>

Number

UMTS/HSPA power reduction. The parameter meaning depends on the product: see Notes for the specific parameter explanation.

<2G_pwr_red_850>,<2G_pwr_red_900>,<2G_pwr_red_1800>,<2G_pwr_red_1900>

Number

GSM/GPRS power customization, for the specific frequency band. The maximum reduction is 6 dB. The parameter meaning depends on the product: see Notes for the specific parameter explanation.

<4G_pwr_red>

Number

LTE power reduction. The parameter meaning depends on the product: see Notes for the specific parameter explanation.

<bitmask1>,<bitmask2>

Number

Indicated the bandmask for LTE band. The parameter meaning depends on the product: see Notes for the specific parameter explanation.

Notes

  • The <3G_pwr_red> parameter has no impact on modules that do not support UMTS/HSPA radio access technology: the parameter is ignored and it can be left empty.

  • The <2G_pwr_red_850>, <2G_pwr_red_900>, <2G_pwr_red_1800>, <2G_pwr_red_1900> parameters have no impact on modules that do not support related GSM/GPRS bands: related parameter is ignored and it can be left empty.

  • <4G_pwr_red> parameters meaning:

    • The range goes from 0 to 12: the power reduction is calculated as <4G_pwr_red> dB. The range of the reduce maximum power limit is [0:12] dB.

    • Missing parameter is not allowed.

    • 0 (factory-programmed value): reset to the factory-programmed maximum Tx power; no power modification.

  • The <bitmask1> and <bitmask2> parameters are not supported.

  • The command setting is stored in the NVM and will be applied at the next module boot.

  • The command setting doesn’t persist after updating the FW version via EasyFlash.

Power configuration command examples

LTE power reduction

Example 1: in the following example an application issues the +UMAXPWR AT command to reduce the maximum Tx power in LTE from the default maximum power of 23 dBm to 19 dBm in the following network configuration:

  • Bandwidth: 5 MHz

  • Uplink resource block number: 1

  • Inside the lowest narrow band

  • Uplink modulation: QPSK

With this network physical layer setting the LTE maximum power reduction (MPR) is 0 dB as per 3GPP TS 36.101 [36.101], 3GPP TS 36.521-1 [36.521-1].

Command

Response

Description

AT+UMAXPWR=4

OK

The custom power reduction is set to 4 dB in all LTE bands.

In LTE the maximum power is reduced by 4 dB.

After the 4 dB reduction the resulting maximum power is 19 dBm as shown in table_title. The setting is applied accordingly to all the LTE bands.

LTE maximum power reduction

PmaxLTE=23 dBm

Default LTE maximum Tx power

RedLTE_MPR=0 dB

LTE maximum power reduction (MPR)

RedLTE_UMAXPWR=4 dB

Requested Tx power reduction

Pmax2LTE=19 dBm

New LTE maximum Tx power

LTE maximum power reduction in case of LTE MPR of 0 dB

Example 2: in the following example an application issues the +UMAXPWR AT command to reduce the maximum Tx power in LTE by 2 dB in the following network configuration:

  • Bandwidth: 5 MHz

  • Uplink resource block number: 25

  • Full bandwidth RB allocation

  • Uplink modulation: QPSK

With this network physical layer setting the LTE maximum power reduction (MPR) is 1 dB as per 3GPP TS 36.101 [36.101], 3GPP TS 36.521-1 [36.521-1].

Command

Response

Description

AT+UMAXPWR=2

OK

The custom power reduction is set to 2 dB in all LTE bands.

In LTE the maximum power is reduced by 2 dB as a result of the +UMAXPWR AT command.

After the 2 dB reduction customization by means of the +UMAXPWR AT command and the LTE MPR of 1 dB the resulting maximum power is 21 dBm as shown in table_title. If the MPR is lower than the requested power reduction, the DUT will apply the requested one. The setting is applied accordingly to all the LTE bands.

LTE maximum power reduction

PmaxLTE=23 dBm

Default LTE maximum Tx power

RedLTE_MPR=1 dB

LTE maximum power reduction (MPR)

RedLTE_UMAXPWR=2 dB

Requested Tx power reduction

Pmax2LTE=21 dBm

New LTE maximum Tx power

LTE maximum power reduction in case of LTE MPR of 1 dB