Narrow down by specifying conditions
現在1889件がヒットしています。check
Realization of ultra-low power consumption
Semtech's LTE Cat-M1 module: HL7800 uses Altair Semiconductor's ALT1250 Chipset, achieving up to approximately 1/10th the power consumption (*1) of competing modules.
This time we will measure current consumption in a real network and analyze the current consumption waveform during eDRX.
(*1): Comparison with typical values when eDRX cycle=20.48[sec]
What is eDRX
eDRX (extended dicontinuous reception) is a type of communication technology in the IoT communication standard LPWA, and operates in LTE Category-M1 and LTE NB-IoT.
In the past, in order to save power, 3gpp Release-8 specified a technology called DRX (Discontinuous Reception) that receives PDDCH signals intermittently, which makes it possible to reduce power consumption by stopping RF functions and going into sleep mode during periods when there is no reception. The DRX cycle was previously a maximum of 2.56 seconds, but eDRX extends this to a maximum of 10.24 [sec] in RRC_CONNECTED, and up to 43.96 minutes in Cat.M1 and 175 minutes in RRC_IDLE. By extending the period of no communication other than reception, it is possible to significantly reduce power consumption in the conventional standby state.
The number of IoT devices, which has been increasing in recent years, generally does not have the use cases of "anytime", "large capacity", and "unlimited" like smartphones, and tends to communicate relatively infrequently, such as once a day for sensing or to keep alive. On the other hand, the increase in battery consumption due to cellular communication has been an issue.
The latest eDRX technology is effective for such IoT devices, and is said to be able to power the battery for XX years with small-volume data communication.
Measurement environment
We will measure current consumption in the following environment.
*HL7800 Development Kit *Introduction is possible from our company.
* Stabilized power supply and ammeter: OTII
*Carrier: Docomo network
＊動作環境：弊社オフィス（20℃/60%）
【procedure】
①: Confirm Network Attach with neighboring base station
②: Set eDRX=81.92[sec] on the terminal side
③: Confirm that parameter ② is accepted by the base station
④: Transition the terminal to eDRX/Hibernate mode
⑤：Waveform observation
Measurement result
Shows the current consumption measurement results during eDRX operation.
This time, we will check the lowest consumption state, eDRX/Hibernate Cycle = 81.92 [sec] (the maximum DRX period currently configurable by the carrier), and compare the average value for 10 eDRX cycles.
As a result, the consumption current value was lower than the specified value in the HL7800: Hardware specification in the left figure.
Current waveform analysis
We will analyze the terminal operation during eDRX based on the measured current consumption waveform.
This time, we will refer to each behavior in [A] block and [B] block.
[A] Block
The above shows the consumption current waveform from eDRX ON to about 15 minutes later.
The processing at each timing is introduced using the communication packet log between the HL7800 and the base station.
[a]:
This is a network attach with a nearby base station. This process completes authentication with the terminal and registers location information, but also notifies/registers various eDRX parameters (T3412, extended-DRX value, etc.).
- T3412: Update Timer for location registration information area. TAU (Tracking Area Update) is implemented at the time of expiration
- extended-DRX value: DRX Paging period. In the case of the figure, it is registered at 81.92[sec]
[b]:
After transitioning to eDRX mode, "RRC Connection Release" will be implemented after a certain period of non-communication. The period until RRC Connection Release is established by the carrier side, and is notified to the terminal side at the time of Network Attach as in [a].
After the RRC Connection Release, the network side will perform initialization to process eDRX. The initialization process will take about 10 minutes depending on the carrier, and during this time paging will be performed irregularly at a different cycle from the extended-DRX value notified in [a]. However, since this process is necessary for stable eDRX operation, the network will continue to maintain the Network Attach state.
[c]:
After eDRX Initialize, Paging starts at the eDRX cycle set in [a], and the terminal transitions to the low power consumption state.
[B] Block
The figure on the left shows the consumption current waveform up to about 5 minutes before the Tracking Area Update process.
[d]:
Tracking Area Update is carried out and the location information registration on the terminal side is notified again.
[e]:
After the Tracking Area Update is executed, the eDRX Initialize process will start again, and then the stable operation will repeat.
Summary
In this article, we measured the power consumption during eDRX of Semtech's LTE Cat-M1 module: HL7800. As a result, we confirmed that the power consumption was reproduced below the hardware specifications in a real network environment. We also introduced the terminal side control during eDRX using waveforms.
In the future, we plan to gradually support the eDRX cycle on the carrier side up to the theoretical value level. Further reduction in consumption is expected after the implementation, and we will introduce it again.
For more information on HL78xx series products, click here.
Inquiry
If you have any questions regarding this article, please contact us below.
Semtech Manufacturer Information Top Page
If you would like to return to the Semtech manufacturer information top page, please click below.