Power consumption characteristics of smartphones and two methods of APP power consumption testing

“The article states the development trend and power consumption characteristics of mobile phones, focuses on the current most concerned issue of smart phone power consumption, and introduces two methods to measure the power consumption of mobile phone software. In addition, it also explained why the operator had previously proposed to charge WeChat fees, and what the heartbeat mechanism was.

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The article states the development trend and power consumption characteristics of mobile phones, focuses on the current most concerned issue of smart phone power consumption, and introduces two methods to measure the power consumption of mobile phone software. In addition, it also explained why the operator had previously proposed to charge WeChat fees, and what the heartbeat mechanism was.

Jon Rubinstein, CEO of Palm, a famous American mobile phone company, once said: “The future development of mobile phones depends on two factors, one is the data transmission speed of the mobile phone; the other is the standby time of the mobile phone.”

Why is phone standby time so important?

Now, the Internet speed of mobile phones has been greatly improved, and the development of 4G and 5G.4G network can increase the Internet speed of mobile phones to more than 100Mbps. The movie is less than 1 minute long. The 5G network that is being developed and planned now can even reach 1Gbps through mobile phones. Therefore, it is conceivable that in the case where the data speed is no longer limited, “smart phones” combined with various application software and “cloud” computing, the future The mobile phone will become a real “mobile terminal”. Mobile ID card, mobile banking, mobile wallet, mobile traffic card, mobile navigation, mobile smart driving…, all things are done through the network using this “mobile phone”.

When the “mobile phone” has become that you can’t live without the “terminal” at all times, is it very fatal if the mobile phone is out of power?

The reasons for the short standby time of the mobile phone are complex, including the power consumption of the mobile phone in standby state, the talk time, the Internet time, the strength of the wireless signal, the GPS navigation, the brightness of the Display screen, the background operation of various software, and the size of the battery capacity, etc., which will affect the standby time. . Usually we are most concerned about the length of time from the last charging of the mobile phone to the time when the mobile phone automatically shuts down or indicates that the battery is low.

To comprehensively analyze and optimize the standby time of a mobile phone, mobile phone, battery, and charging management are indispensable. For the time being, let us call them “three-piece mobile phone sets”. So let’s start with the power consumption characteristics of mobile phones!

Mobile phone development trends and power consumption characteristics

Smartphones are becoming more and more popular, their hardware processing capabilities are becoming stronger and stronger, and more and more software applications are supported.

We can’t help but have another concern. The standby time of the current smartphone is already a shortcoming. Will the standby time of the future smartphone become even shorter?
In theory, larger displays, more core processors, and more diverse wireless connection technologies will definitely increase the power consumption of mobile phones. At the same time, mobile phones have more and more functions, and mobile phones are used more and more frequently. Therefore, it becomes more important to optimize and manage the power consumption performance of mobile phones. For example, when the mobile phone is not operated, it can enter sleep faster, transmit wireless signals in the form of pulses, discontinuous reception and discontinuous transmission, etc.

In order to optimize and improve the power consumption of the mobile phone, it is necessary to first understand the characteristics of the power consumption of the mobile phone or discover the defects in the power consumption performance of the mobile phone, so as to be targeted.
The characteristics of mobile phone power consumption can be summarized into the following aspects:

1. The current amplitude fluctuates greatly:
a) Shutdown leakage current: ~10 to 100nA
b) Sleep current: ~100μA to 10mA
c) Standby current: ~5 to 50 mA
d) Receive status: ~100 to 300 mA (pulse)
e) Transmit state: ~1 to 2.5 A (pulse)
f) Application software running: ~100mA to 2A
2. The current changes quickly and dynamically:

The above picture is the current waveform of GPRS mobile phone transmitting Tx and receiving Rx:
a) The transmit TX current pulse is 0.58 ms and the current is 2.02A;
b) Receive RX current pulse for 1.2ms, current 143 mA
c) Continuous emission of Tx current pulse interval is 4.6 ms;
d) The current in the idle Idle state is 1mA.
3. The current is a combination of multiple functions, and it is difficult to distinguish who caused the current:

The above picture is the current waveform of the mobile phone from Idle to the display screen, and then to dialing and making a call; in the position where the display is turned on and the mobile phone is transmitting, the combined current of the two superimposes the current.

4. It usually takes a long time to track and observe the current

As shown in the figure above, it is necessary to test the call duration of the mobile phone, continuously record the changes of current and voltage for 4 hours, analyze the power consumption (843mAh) during the call, and also need to accurately measure the pulse current, which often becomes very difficult.

The power consumption of the application software on the mobile phone

Why does the operator say that it proposes to charge WeChat fees?

Generally, more than 15-20% of the power of an Android phone is consumed by sending excessively frequent heartbeats every day.

WeChat, you must be familiar with it, right? This is how WeChat is introduced online:

WeChat is a faster instant messaging tool with zero tariffs, cross-platform communication, display of real-time input status, and other functions. Compared with traditional SMS communication, it is more flexible, smarter, and less expensive. Optimized for pictures, voice and video, 1M can send about 1,000 text messages, 1,000 seconds of voice messages, and about 1 minute of video messages; WeChat has a well-designed communication protocol, which consumes very little traffic when running in the background, and consumes a month. About 1.7M traffic.
Earlier, there was a news that WeChat would start charging. Everyone will be curious – why do you charge? Who will be charged? What is the fee charged? Let’s talk about this below.

WeChat transmits content such as text, pictures, voice or video through data services. Therefore, as long as you use WIFI or monthly data subscription, it can be completely free. Therefore, as long as software developers such as Tencent do not charge software fees, theoretically users have no reason to pay any fees.

However, due to the large number of users and the scarcity of resources in a mobile communication network, each user dynamically occupies resources, such as IP addresses and wireless channels. In order to realize instant messaging, WeChat software periodically sends resource allocation requests to the mobile communication network, and it remains online even if it runs in the background. This mechanism is also referred to as the “heartbeat mechanism”.

The earliest heartbeat mechanism is used as a security backup mechanism for servers to prevent the server from crashing, and dedicated ports and lines are used between servers to periodically transmit brief information. Heartbeat is an image metaphor. Once the other party’s heartbeat information is not received, the server can take over the other party’s business to avoid business stagnation. For the smooth operation of the business, the heartbeat information sent by the server can be very frequent.

This mechanism is borrowed by Internet applications on mobile phones. Whether it is Android’s native applications, or QQ, Weibo, and WeChat, this heartbeat mechanism is used, that is, the terminal regularly sends short messages to the application server. For example, the heartbeat cycle of the old version of QQ is 30 seconds, the new version of QQ is 3 minutes, WeChat is 5 minutes, and Google’s native application is about 28 minutes. Every time a mobile phone sends a heartbeat packet, the mobile communication network needs to allocate resources for the user, and the allocation process is reflected in the sending and receiving of signaling. The sending process of a heartbeat packet involves dozens of signaling. Operators of signaling information allocated by these network resources cannot charge for it, just like when a phone call is not connected, a lot of signaling information is exchanged and users do not need to pay.

In an interview with the media, Huang Xiaoqing, President of China Mobile Research Institute, expressed the pressure that WeChat business brings to operators, saying that WeChat only brings 10% of China Mobile’s mobile data traffic, but occupies 60% of its signaling resources . This is also understood by the outside world as the direct reason for charging WeChat.

Now we finally understand, why do operators such as China Mobile charge WeChat fees? The data traffic fee for sending and receiving WeChat content such as pictures, voice or video, etc., has been charged (it is only included in our monthly data traffic package), and the “heartbeat” fee of WeChat is also charged!

In fact, operators don’t even think about it. Without this kind of “heartbeat”, where will the data traffic be charged later?

Of course, innovative communication software platforms such as WeChat have indeed affected operators’ income from SMS, MMS, and even calls, but this is a historical trend that no one can stop.

Charged or not, this “heartbeat” also means that your phone will be woken up from its standby power-saving state nearly 300 times a day, equivalent to making a phone call for a few seconds each time. A rough calculation shows that more than 15-20% of the power of an average Android phone is consumed by sending excessively frequent heartbeats every day.

In order to prolong the standby time of the mobile phone, it is recommended to close the background operation if it is not used for a long time.