# Duty Cycle - Time on Air

**URL:** <https://www.thethingsnetwork.org/forum/t/duty-cycle-time-on-air/122>\
**Category:** TTN Network and Services\
**Created:** [September 24, 2015, 11:20am UTC](https://www.thethingsnetwork.org/forum/t/duty-cycle-time-on-air/122 "2015-09-24T11:20:20Z")\
**Posts on this page:** 1\
**Showing post:** 16

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**Author:** ![arjanvanb](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/arjanvanb/32/46626_2.png) [@arjanvanb](https://www.thethingsnetwork.org/forum/u/arjanvanb)\
**Post date:** [April 23, 2016, 11:34am UTC](https://www.thethingsnetwork.org/forum/t/duty-cycle-time-on-air/122/16 "2016-04-23T11:34:40Z")

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> [@d21d3q](#):
>
> how is handled need of sending ACKs uplink packets by gateway? Time on Air of Gateway will be multiplicated by number of nodes?

It would, if all nodes would always use confirmed uplinks. But nodes should not do that; [you can’t send all messages as ‘confirmed uplink’](https://www.thethingsnetwork.org/forum/t/limitations-data-rate-packet-size-30-seconds-day-fair-access-policy-nodes-per-gateway/1300):

> All devices have to comply with these regulations, so that includes gateways. As a result, downlink capacity of the network is even smaller than uplink capacity. This means that you should use unconfirmed messages unless you really need confirmed messages and send as little downlink data messages as possible.

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