nRF7002dk UDP Client Power Consumption

RE: nRF7002dk UDP Client Power Consumption

Marte Myrvold — Thu, 21 Dec 2023 14:48:39 GMT

Hi Julian,

Please keep me posted if you find anything! I will do the same.

I will start my vacation after tomorrow, and will be out of office until 2nd of January. If you have critical issues you can create a new ticket which will be assigned to one of the engineers working next week. Please note that due to reduced staffing there will be an increase in response time during the holidays.

Happy holidays! 🙂

Best regards,
Marte

RE: nRF7002dk UDP Client Power Consumption

JulianKaroliny — Wed, 20 Dec 2023 15:54:52 GMT

Hey Marte,

I will try to use a different server (and maybe also a different AP) and check if the problem is on that end.
Thanks again for your fast replies and for your help. If I find anything new I will reach out here again or give an update.

best,
Julian

RE: nRF7002dk UDP Client Power Consumption

Marte Myrvold — Wed, 20 Dec 2023 15:45:26 GMT

Hi Julian,

Have you tested with a different network or different server?

I am not able to reproduce the behavior you are seeing. I am testing with the Wi-Fi shell sample and sending with net udp send. When sending to an echo server I get two plateaus shortly after each other, and I could verify that the second was due to Power-Save poll and receiving response from the server based on the timing. When testing with a server that did not respond I only saw one plateau for the UDP and ACK.

[quote user="JulianKaroliny"]Do you think that if I try to create raw UDP packets with this sample I can achieve small transmission peaks without this long time until the device goes to sleep - or would I end up with the same result?[/quote]

I do not think this sample will help. By default power saving is turned off in the sample (CONFIG_NRF_WIFI_LOW_POWER=n), so it is not intended to be used with power saving.
The sample sends raw 802.11 packets, so the fields of the MAC header are manually set in the code and you would have to set the fields of the NWK layer as well for the UDP packet.

Best regards,
Marte

RE: nRF7002dk UDP Client Power Consumption

JulianKaroliny — Tue, 19 Dec 2023 11:12:22 GMT

Hello Marte,

I updated the PPK2 but I have the same/similar results:

I am pretty sure that where the marker starts is the start of the UDP transmission and the ACK is directly after that. But I measure nothing after which would explain the second plateau.

I also observed these ARP messages from your measurement with "who has ...." but not in the one I sent to you. And they are not very frequent.
Anyway, there is still the chance that I am missing something crucial or doing something wrong in the measurements.

Additionally, I just saw that there is a (new?) example in the SDK "Wi-Wi: Raw TX packet". Do you think that if I try to create raw UDP packets with this sample I can achieve small transmission peaks without this long time until the device goes to sleep - or would I end up with the same result?

br
Julian

RE: nRF7002dk UDP Client Power Consumption

Marte Myrvold — Tue, 19 Dec 2023 10:02:42 GMT

Hi Julian,

I saw these additional spikes as well when testing yesterday. However, after I updated the Power Profiler app to v4.0.0-beta3 today and I no longer see the spikes when testing. I know there was a fix related to noise in the latest PPK2 firmware, but I do not know if it is related to this or not.

Can you try updating as well and see if there is a difference? Please note that you will also have to update the firmware of the PPK2. You should get a prompt to update when selecting the PPK2 in the drop-down menu.

I also saw spikes similar to yours shortly after the UDP transmission, but this was related to Power-Save poll sent from the device to AP and address resolution protocol (ARP) packet from AP to the device. All of this should show up in the Wireshark capture though, so it does not seem to be the case in your test since there are no packets.

Best regards,
Marte

RE: nRF7002dk UDP Client Power Consumption

Marte Myrvold — Mon, 18 Dec 2023 14:55:49 GMT

Hi Julian,

I will test this and get back to you tomorrow.

Best regards,
Marte

RE: nRF7002dk UDP Client Power Consumption

JulianKaroliny — Fri, 15 Dec 2023 11:56:48 GMT

Hey Marte,

thanks again for your answer and for being patient with me :-D

I set up the wifi shell and you are right, the nrf70 stops sending Null functions for wifi ps_timeout 0

However, I am still confused by the results of my measurements:
Setup: Wifi shell, network card in monitor mode, PPK2, wifi ps_timeout 0

I checked what exactly happens for the UDP transmission so I did
"net udp send 192.168.1.1 4242 hallo"

On the network sniffer, I get exactly the one UDP transmission + Block ACK
This can be seen also on the PPK measurements but after a short time in sleep, it wakes up again. For the second wakeup, I cannot sniff any corresponding packet sent to or from the nrf70.

Here is the output of the PPK2:

The marked one is the UDP transmission with the ACK. The one directly after I have no idea.

(Mind I don't see this "2 Blocks" every time, but often enough)

i don't know If I am doing something wrong :-D

best
Julian

RE: nRF7002dk UDP Client Power Consumption

Marte Myrvold — Thu, 14 Dec 2023 16:49:36 GMT

Hi Julian,

Are you able to capture a sniffer log of this?

[quote user="JulianKaroliny"]1. Is there any way to prevent the module from sending these Null functions or to do it immediately [/quote]

It should be disabled if you set the timeout to 0. I just tested with the Wi-Fi Shell sample using wifi ps_timeout 0 and net udp send. With timeout disabled I did not see any Null functions in the wireshark capture like I did when timeout was enabled.

[quote user="JulianKaroliny"]2. Even in the cases where it worked, the 20ms up-time is still very high if compared for example to the DTIM messages. It would be nice if the module only is in receiving when there is something planned to receive.[/quote]

The device receives MAC layer ACK after sending the UDP message. In addition to this, the device also sends a Power-Save poll to retrieve any buffered packets from the AP since it is awake. This is based on the 802.11 specification.

[quote user="JulianKaroliny"]3. In the UDP example for the nrf91 there is something called RAI to tell the module that there are no further messages - is there something similar for the nrf70[/quote]

RAI is only supported on the nRF91.

[quote user="JulianKaroliny"]4. I found another timeout parameter for the kconfig but I have no idea what it does:[/quote]

I will check this internally and get back to you.

Best regards,
Marte

RE: nRF7002dk UDP Client Power Consumption

JulianKaroliny — Wed, 13 Dec 2023 09:33:34 GMT

Hello Marte,

Thank you for your answer and sorry for the late response.

I tried your fix and added the following lines:

struct wifi_ps_params params = { 0 };
struct net_if *iface = net_if_get_default();
long timeout_ms = 0;
params.timeout_ms = timeout_ms;
params.type = WIFI_PS_PARAM_TIMEOUT;
net_mgmt(NET_REQUEST_WIFI_PS, iface, &params, sizeof(params));

and it seems to sometimes reduce the uptime - but not every time.
I attached again a picture from the PPK2:

We can see that for the marked UDP transmission, the up-time is reduced to around 20ms. However, in half of the cases, it seems that the module goes to sleep, and then wakes up (my guess would be to send the NULL-Function because there is a single transmission in the beginning) to then go to sleep again.
So there might be still a problem somewhere.

I would have still some open questions:

1. Is there any way to prevent the module from sending these Null functions or to do it immediately

2. Even in the cases where it worked, the 20ms up-time is still very high if compared for example to the DTIM messages. It would be nice if the module only is in receiving when there is something planned to receive.

3. In the UDP example for the nrf91 there is something called RAI to tell the module that there are no further messages - is there something similar for the nrf70

4. I found another timeout parameter for the kconfig but I have no idea what it does:

config NRF700X_RPU_PS_IDLE_TIMEOUT_MS
	int "RPU power save idle timeout in milliseconds"
	default 10

Thank you again for your time and I hope we can find a solution for this. Really Low-power UDP transmissions would be a nice feature.

br
Julian

RE: nRF7002dk UDP Client Power Consumption

Marte Myrvold — Thu, 07 Dec 2023 14:44:45 GMT

Hi Julian,

I have an update already 🙂

The default power save timeout is 100ms, so the behavior you are seeing is expected. This power save timeout can be changed by sending a network management request.

Here is a code snippet for setting the timeout. Change timeout_ms to the power save timeout you want.

struct net_if *iface = net_if_get_first_wifi();
struct wifi_ps_params params = { 0 };
long timeout_ms = 100;

params.timeout_ms = timeout_ms;
params.type = WIFI_PS_PARAM_TIMEOUT;

if(net_mgmt(NET_REQUEST_WIFI_PS, iface, &params, sizeof(params))) {
	LOG_ERR("Setting PS timeout failed. Reason: %s", wifi_ps_get_config_err_code_str(params.fail_reason));
}

If you have shell enabled you can also configure this with the shell command wifi ps_timeout <timeout>.

Best regards,
Marte

RE: nRF7002dk UDP Client Power Consumption

Marte Myrvold — Thu, 07 Dec 2023 14:05:13 GMT

Hi Julian,

I agree, it seems like the reason for the long awake time is that the nRF70 waits some time before sending the NULL function to the AP. I have asked the development team if there is a way to decrease the time before the nRF70 sends this packet or if there are any other ways to decrease the total time. I will let you know when I have an update.

Best regards,
Marte

RE: nRF7002dk UDP Client Power Consumption

JulianKaroliny — Tue, 05 Dec 2023 16:16:07 GMT

One small but maybe important addition

I now used an external WiFi card in monitor mode to see the actual communication. Here is one snippet of wireshark:

- The duration of the UDP packets is around 260us (NRF MAC: F4:CE....) which is in no relation to the 150ms of high power consumption. It seems that the amount of data needs 3 UDP packets for one send() command
- The AP (MAC: E4:5F....) directly block acknowledges in nearly no time

But now comes the interesting part:
around 100ms after the last UDP the nRF70 always sends a NULL Function packet (see image).
Google says: Null Function (Null data)- Notifies the AP to change the power save status by updating the Power Management bit.

It seems like the nRF70 is waiting some time until it decides to sleep and sends this NULL Function message to the AP. It also send a Null Function packet to the AP after waking up. Maybe this helps you find a solution.

br
Julian

RE: nRF7002dk UDP Client Power Consumption

JulianKaroliny — Tue, 05 Dec 2023 15:34:11 GMT

Hey Marte,
Thank you for looking into the topic.

Also, thanks for the code to define the wakeup mode, however, this I already tried. Similar lines can also be found in the main() of the code I provided you (although they are commented out).
Sadly as you might guess the DTIM is not the problem here, especially since I want to increase the UDP transmission rate.

For me, it looks like the nrf7001 goes into receive mode after the UDP transmission, but I cannot verify this. Maybe this can be deactivated somehow?
The ~150ms after the UDP transmissions are simply too long - the actual communication should be way quicker. I also reduced the amount of data but this does not affect this time interval.

This might be also interesting: If you look at the figure I provided, the "active time" is not the same every time. It varies sometimes strongly between the UDP transmissions.

I hope we can find a solution to this problem to make the nRF70 a low-power beast.

best
Julian

RE: nRF7002dk UDP Client Power Consumption

Marte Myrvold — Tue, 05 Dec 2023 15:17:54 GMT

Hi Julian,

I have not been able to find a way to reduce the awake time for the UDP transmission, but I have asked internally.

Another thing you do to reduce the power consumption is to use listen interval instead of DTIM as wakeup mode. You can set listen interval with the following:

struct net_if *iface = net_if_get_default();

struct wifi_ps_params params = {0};
params.wakeup_mode = WIFI_PS_WAKEUP_MODE_LISTEN_INTERVAL;
params.type = WIFI_PS_PARAM_WAKEUP_MODE;
params.listen_interval = // your interval

if (net_mgmt(NET_REQUEST_WIFI_PS, iface, &params, sizeof(params))) {
	LOG_ERR("Setting wakeup mode failed. Reason %s",
		wifi_ps_get_config_err_code_str(params.fail_reason));
	return -1;
}

Best regards,
Marte

RE: nRF7002dk UDP Client Power Consumption

Marte Myrvold — Mon, 04 Dec 2023 10:06:48 GMT

Hi Julian,

I have started looking into this and will get back to you later today.

Best regards,
Marte