Shulou(Shulou.com)11/24 Report--

With the development of 5G network, people feel the convenience of 5G network, but the high power consumption of terminals in 5G network has always been an unavoidable topic. In order to improve terminal energy efficiency, 5G has introduced many new features.

The previous document introduced UAI (UE Assistance Information, user equipment Auxiliary Information) energy-saving technology, you can use the "5G mobile phone more electricity? don't panic, UAI will do it!" Learn more about the technology.

This time, Mr. document introduces another energy-saving technology, WUS (Wake Up Signal, wake up signal). On the basis of C-DRX (Connected Discontinuous reception), WUS adds a wake-up signal to indicate whether the terminal should wake up in the next cycle to monitor the scheduling.

First of all, let's introduce how C-DRX works.

C-DRX refers to the DRX (Discontinuous reception, discontinuous reception) function of the terminal in the connected state. Through C-DRX, the terminal can periodically go to sleep at certain times without listening to PDCCH (Physical Downlink Control Channel, physical downlink control channel).

The figure above is an example of a typical DRX cycle.

On Duration: active, the terminal will remain awake and receive the PDCCH.

Opportunity for DRX: sleep state, terminal sleep, do not receive PDCCH. The extent to which the terminal can save power depends on the length of that part of the time.

This mechanism can make the terminal wake up and sleep periodically, but in the practical application scenario, the terminal will not send or receive data continuously, that is to say, in most of the wake-up phase, the terminal will not receive PDCCH. For example, when we are reading cached web pages on our mobile phone, we don't need to interact with the Internet.

If the terminal still wakes up periodically, this will result in additional power consumption. Therefore, on the basis of the original C-DRX mechanism, in order to optimize the power consumption of the terminal, the WUS function is proposed in 3GPP 5G R16.

By sending DCI 2-6, the base station side informs the terminal in advance whether it needs to wake up to monitor the PDCCH during the C-DRX On Duration. If it does not need to wake up, it can further reduce the PDCCH monitoring time and improve the power-saving performance.

So what is WUS?

WUS is Wake-up signal, and this "signal" is a special PDCCH, scrambled by Ps-Rnti. The WUS is sent by the base station side before the DRX On Duration to indicate whether the terminal is going to wake up at the next DRX On Duration. As mentioned above, in C-DRX, the terminal periodically wakes up to listen for PDCCH. On the basis of C-DRX, WUS adds such a signal to indicate whether the terminal should wake up in the next cycle to listen to PDCCH.

As shown in the figure, when the WUS function is supported, the base station can send WUS before DRX On Duration. The base station sends WUS to the terminal through DCI 2-6, and determines whether the terminal wakes up at the next DRX On Duration by detecting the value of Wake Indication in DCI 2-6.

If Wake Indication=1 is detected, the terminal should be woken up and listen for PDCCH conditions, such as traditional C-DRX.

If Wake Indication=0 is detected, the terminal can skip the entire C-DRX cycle and do not detect any PDCCH.

In the traditional C-DRX cycle, the terminal is always active during the On Duration, and it needs to wake up and listen to the PDCCH even if there is no data.

After introducing the WUS function, the base station side will inform the terminal whether it needs to wake up during the On Duration period through DCI 2-6 before the On Duration is activated. If you do not need to wake up, the terminal will not wake up during the On Duration period of the DRX cycle, that is, the terminal will no longer listen to the PDCCH during the whole DRX cycle. Compared with the traditional C-DRX, the power saving effect is more obvious.

This is the end of the introduction on the function of WUS. What other technologies do you want to know? you can leave a comment. The documentation has been sorted out and will continue to be introduced to you.

This article comes from the official account of Wechat: ZTE documents (ID:ztedoc)

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