QUECTEL EC2x LTE Standard Module Software User Guide
- June 16, 2024
- QUECTEL
Table of Contents
**QUECTEL EC2x LTE Standard Module Software User Guide
**
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About the Document
Revision History
Introduction
This document describes the AT commands related to the software thermal mitigation policy on Quectel LTE Standard EC2x, EG9x, EG2x and EM05 family modules. When the temperature reaches a specific threshold, the thermal mitigation policy is implemented to cool down the module.
Applicable Modules
Table 1: Applicable Modules
| Module Family | Module |
|---|---|
| EC2x | EC25 series |
EC21 s
EC20-CE
EG9x| EG95 series
EG91 series
EG2x| EG25-G
EG25-GL
EG21-G
EG21-GL
EM05| EM05 series
AT Command Description
AT Command Introduction
Definitions
- Carriage return character.
- Line feed character.
- <…> Parameter name. Angle brackets do not appear on the command line.
- […] Optional parameter of a command or an optional part of TA information response. Square brackets do not appear on the command line. When an optional parameter is not given in a command, the new value equals its previous value or the default settings, unless otherwise specified.
- Underline Default setting of a parameter.
AT Command Syntax
All command lines must start with AT or at and end with . Information responses and result codes always start and end with a carriage return character and a line feed character: . In tables presenting commands and responses throughout this document, only the commands and responses are presented, and and are deliberately omitted.
Table 2: Types of AT Command
| Command Type | Syntax | Description |
|---|---|---|
| Test Command | AT+=? | Test the existence of the corresponding command and |
return information about the type, value, or range of its parameter.
Read Command| AT+?| Check the current parameter value of the corresponding
command.
Write Command| AT+=[,[,[…]]]| Set user-definable parameter value
Execution Command| AT+| Return a specific information parameter or perform a
specific action.
Declaration of AT Command Examples
The AT command examples in this document are provided to help you learn about the use of the AT commands introduced herein. The examples, however, should not be taken as Quectel’s recommendations or suggestions about how to design a program flow or what status to set the module into. Sometimes multiple examples may be provided for one AT command. However, this does not mean that there is a correlation among these examples, or that they should be executed in a given sequence.
AT+QTEMP Query Module Temperature
This command queries module temperature.
AT+QTEMP Query Module Temperature
Test Command AT+QTEMP=?| Response OK
Execution Command AT+ QTEMP| Response + QTEMP:
OK Or ERROR
Maximum Response Time| 300 ms
Characteristics| /
Parameter
- Integer type. Baseband temperature. Unit: Degree Celsius. Integer type.
- XO temperature. Unit: Degree Celsius. Integer type.
- PA temperature. Unit: Degree Celsius.
Example
AT+QTEMP //Query module temperature.
+QTEMP: 30,28,27
OK
AT+QCFG=”thermal/modem” Set Thermal Mitigation Policy
This command sets the thermal mitigation policy. The configured policy will be triggered by the highest temperature value queried by AT+QTEMP.
AT+QCFG=”thermal/modem” Set Thermal Mitigation Policy
Write Command AT+QCFG=”thermal/modem”[, < level>,
Parameter
Integer type. Thermal mitigation level. Each level corresponds to a set of and .
- Level 1 – uplink data rate is limited (See Chapter 3.1.1)
- Level 2 – downlink data rate is limited based on level 1(See Chapter 3.1.2)
- Level 3 – module enters Limited-Service Mode. In Limited-Service Mode, data calls are not allowed. UE only allows emergency voice calls. (See Chapter 3.3)
Integer type. Temperature threshold of triggering. When the module temperature reaches the threshold, thermal mitigation policy of the corresponding level () will be triggered. Unit: 0.001 ºC.
If =1, is the temperature threshold for reducing uplink data rate. Default value: 100000.
If =2, is the temperature threshold for reducing downlink data rate. Default value: 105000.
If =3, is the temperature threshold for entering Limited-Service Mode. Default value: 115000
Integer type. Terminating threshold. When the temperature is lower than the threshold, thermal mitigation policy of the corresponding level () will be cancelled. Unit: 0.001 ºC.
If =1, is the temperature threshold for cancelling uplink data rate reduction. Default value: 95000.
If =2, is the temperature threshold for cancelling downlink data rate reduction. Default value: 100000.
If =3, is the temperature threshold for exiting Limited-Service Mode. Default value: 105000.
Example
AT+QCFG=”thermal/modem”,1,100000,95000
Cool down the device by limiting uplink data rate at Level 1. If the temperature reaches 100 ºC, the device starts limiting the uplink data rate; if the temperature drops below 95 ºC, it stops limiting uplink data rate and exits Level 1.
OK
AT+QCFG=”thermal/modem” //Query thermal mitigation level.
- +QCFG: “thermal/modem”,1,100000,95000
- +QCFG: “thermal/modem”,2,105000,100000
- +QCFG: “thermal/modem”,3,115000,105000
AT+QCFG=”thermal/txpwrlmt” Control Transmit Power
This command controls the thermal mitigation policy.
AT+QCFG=”thermal/modem” Set Thermal Mitigation Policy
Write Command AT+QCFG=”thermal/modem”[, < level>,
Parameter
AT+QCFG=”thermal/limit_rates” Enable/Disable Thermal Mitigation
Write Command AT+QCFG=”thermal/limit_rates “[,
| mitigation:OKOrERROR
Maximum Response Time| 300 ms
Characteristics| The command takes effect after the module is rebooted.The
configurations will be saved automatically.
Integer type. Enable/disable transmit power control. 0 Disable 1 Enable Integer type. Temperature sensor ID. It corresponds to the temperature value detected by the sensor that is returned by AT+QTEMP. 2 Baseband temperature sensor (Default value. It is recommended not to modify it.) 5 PA temperature sensor 7 XO temperature sensor Integer type. Temperature thresholds that restrict the transmit power. Range: -150–150. Default value: 105. Unit: ºC. Integer type. Length of temperature detection cycle. Range: 1000–360000. Default value: 1000 (It is recommended not to modify it.). Unit: ms. Integer type. Number of times transmit power detection thresholds have been triggered. Range: 1–10000. Default value: 3 (It is recommended not to modify it.). Integer type. Number of times power recovery detection thresholds have been triggered. Range: 1–10000. Default value: 10 (It is recommended not to modify it.).
Example
AT+QCFG=”thermal/txpwrlmt”,1,2,105,1000,3,10 //Enable transmit power control.
OK
AT+QCFG=”thermal/txpwrlmt” //Query the transmit power setting.
+QCFG: “thermal/txpwrlmt”,1,2,105,1000,3,10
OK
AT+QCFG=”thermal/limit_rates” Enable/Disable Thermal Mitigation
This command enables/disables the thermal mitigation policy.
AT+QCFG=”thermal/limit_rates” Enable/Disable Thermal Mitigation
Write Command AT+QCFG=”thermal/limit_rates “[,
| mitigation:OKOrERROR
Maximum Response Time| 300 ms
Characteristics| The command takes effect after the module is rebooted.The
configurations will be saved automatically.
Thermal Mitigation Policy
Limit Data Rate
The workload of components such as CPU and PA can be reduced by limiting data rate. However, the thermal mitigation is not effective in case of no data or low data rate. If AT+QCFG=”thermal/modem”,1,, is executed, the module limits the uplink data rate to lowering temperature; and
if AT+QCFG=”thermal/modem”,2,, is executed, the module limits the downlink data rate once a certain temperature threshold is exceeded.
Limit Uplink Data Rate
When the temperature reaches Level 1, it will set the maximum transmit rate to
40 Mbit/s (target_rate[1]).
The detection cycle of the temperature sensor is 3 seconds by default. If the
temperature is still at Level 1 (or the temperature rises, the module reaches
Level 2) after 3 seconds, the transmit rate will drop to 20 Mbit/s
(target_rate[2]). The temperature is detected every 3 seconds. If the
temperature is still higher than the terminating threshold, the transmit rate
level will increase until the transmit rate drops to 4 Mbit/s
(target_rate[9]). After the temperature of the module drops below the
terminating threshold, the transmit rate will return to 50 Mbit/s
(target_rate[0]) step by step.
Table 3: Uplink Rate Threshold Levels
| Parameter Category | Parameter ID | Value (In Decimal) |
|---|---|---|
| Number of uplink rate threshold levels | num_states | 10 |
NOTE
-
The uplink rate threshold levels in the above table are the default values automatically configured by
the module to enable the software thermal management policy. In the test procedure, they are
different for different modules, and are affected by the module’s own state, heat dissipation, and surrounding environment. -
When performing the test on CMW500, the software thermal management policy can be triggered only if a non-00101 blank SIM card is used.
Limit Downlink Data Rate
PUCCH is an uplink physical channel that carries UCI (Uplink Control Information). The PUCCH cycle is 200 ms (Time On + Off). ACK/NACK is sent in PUCCH when the cycle is on and ACK/NACK is not sent in PUCCH when the cycle is off. Once the module enters Level 2, State 3 (On: 100 ms; Off: 100 ms) is the default downlink rate reduction cycle. If the temperature is at Level 2 for 10 seconds, the reduction cycle will be limited to State 2 (On: 80 ms; Off: 120 ms); The temperature is detected every 10 seconds. If the temperature is still higher than the terminating threshold, the state level will gradually decrease until it falls to State 0 (On: 30 ms; Off: 170 ms). After the temperature of the module drops below the terminating threshold, the state level will recover step by step until the downlink rate returns to normal. See the table below for details.
Table 4: PUCCH cycle of Downlink Rate Reduction
| Parameter | Value |
|---|---|
| PUCCH cycle | 200 ms |
| Number of classes | 6 |
| Default state for thermal mitigation | 3 |
| Default state for CPU-based flow control | 3 |
| State 0 (timer [0]) | On: 30 ms; Off: 170 ms |
| State 1 (timer [1]) | On: 60 ms; Off: 140 ms |
| State 2 (timer [2]) | On: 80 ms; Off: 120 ms |
| State 3 (timer [3]) | On: 100 ms; Off: 100 ms |
| State 4 (timer [4]) | On: 120 ms; Off: 80 ms |
| State 5 (timer [5]) | On: 140 ms; Off: 60 ms |
| Step timer for each state | 10000 m |
Default state for each CPU-based flow control 400
NOTE
- The module cannot directly control the downlink rate but tries to force the network to limit the downlink rate by not returning the network ACK at the wireless protocol stack level. This requires the support of the protocol between the module and the network, but the rate threshold is uncontrollable.
- When the module enters Level 2, the thermal mitigation policy of both Level 2 and Level 1 takes effect at the same time, i.e., the module limits the uplink and downlink data rate simultaneously.
Limit PA Power
Restricting the PA power is a good way to lighten PA workload. However, the transmit power in field test is configured by the network. If the network signal is relatively good, the transmit power is generally not high, and thus the thermal mitigation is not effective by limiting the transmit power.
When the transmit power is restricted and lower than that of the configured
network, the network may not
be able to receive the signal sent by the module or decode the signals,
resulting in a decrease in the data transmission performance.
The transmit power affects the power consumption and heat of the PA, and
theoretically module
temperature can be reduced by limiting the transmit power. The transmit power
is divided into eight levels Level 0–Level 7, which respectively correspond to
different maximum transmit power levels 22–15 dBm.
For example, if transmit power control is enabled with
AT+QCFG=”thermal/txpwrlmt”,1,2,105,1000,3,10,
the module will detect the current temperature every second (1000
milliseconds), and transmit power detection thresholds can be triggered 3
times, by default. If the temperature is higher than 105 ºC for 3 seconds, the
highest transmit power of the module will be reduced by 1 dBm, until the
lowest transmit power drops to 15 dBm. If the current module temperature is
below 105 ºC for 10 consecutive detection cycles (10 seconds), the maximum
transmit power will be increased by 1 dBm until it reaches 22 dBm.
Enter Limited-Service Mode
If the module cannot be cooled down by limiting the uplink data rate and restricting PA power, the module will stop all services to protect the hardware from damage due to overheating.
According to the temperature threshold set with AT+QCFG=”thermal/modem”,3,,, the module enters Limited-Service Mode to lower the temperature. For example, if the thermal mitigation levels are set by
AT+QCFG=”thermal/modem”,3,115000,105000, when the module temperature reaches 115 ºC, the module enters Level 3 and allows only emergency voice calls.
NOTE
After executing Level 3 thermal mitigation, the module can restore all functionalities only after its temperature drops below the temperature threshold for exiting Level 1 thermal mitigation.
Reboot the Module
When the temperature of the module reaches about 120 ºC, it will automatically reboot to protect the hardware. Please note that you can manually configure neither the policy nor the temperature threshold
Appendix Reference
| Abbreviation | Description |
|---|---|
| ACK | Acknowledgement |
| CPU | Central Processing Unit |
| LTE | Long-Term Evolution |
| NACK | Negative Acknowledgement |
| PA | Power Amplifier |
| PUCCH | Physical Uplink Control Channel |
| SIM | Subscriber Identity Module |
| TA | Terminal Adapter |
| XO | Crystal Oscillators |
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