4g LTE-M solution

[versacardio]

We are in development of a wearable ecg medical device. We want to add 4g low power capability. The device is a patch worn by patients 24/7 up to 30 days. Our current requirements is to transfer 90 second transmissions of 22,500 bytes. That is in a 24 hour period 960 separate transmissions of 90 seconds, for a total of 21,600,000 bytes. We need to determine what battery size is sufficient to power your 4g solution so we can decide to purchase. We need a response very fast. Thank You Darin Slack

[Jørgen Holmefjord]

Hi,

We cannot give you any definite recommendations on battery size, as this will depend both on other components in your system, and the application you run on the nRF91. The current consumption of the device will also be affected by what features are supported by the network carrier in the area where your product will be used, and the coverage in the area.

What I can give you are the current estimates for the data upload from the nRF91, given that the device is connected to the network, and that the network carrier supports the parameter used for the calculations:

LTE-M1, RRC idle eDRX interval = 10.24s, Connected DRX interval = 0.032s, 960 uploads/day @ 22.5 kB: Total Average current modem: 5074.17 uA

Note that your application current consumption will come in addition to this. When the device is not connected to the network, the modem will consume 45 mA while scanning. If you are concerned about battery life, you should consider adding a limitation in the application on how long it should try to connect to the network. You may also get different results based on your network carrier's supported parameters. You should check with the carrier if eDRX idle is supported, and if so, which intervals are supported. Also, ask about the connected DRX interval.

Best regards,
Jørgen