v1.0

LTE-M and LTE-NB

HD-FDD LTE-M and HD-FDD LTE-NB have different uplink ratios over radio frame and maximum continuous uplink durations. Both systems are based on a 10 ms radio frame consisting of 10 subframes (SF), 1 ms each.

In normal network signaling conditions without uplink repetitions, the number of continuous uplink and downlink subframes may differ noticeably between the systems. In HD-FDD LTE-M, the maximum uplink ratio can be 3 SF/10 SF (33%), whereas in HD-FDD LTE-NB it can be 8 SF/10 SF (80%). This means that in HD-FDD LTE-NB, the uplink can be transmitting approximately three times longer per radio frame than in HD-FDD LTE-M.

However, with uplink repetitions, both systems share the same uplink ratio of 86%. Power consumption at high output power levels for HD-FDD LTE-M is approximately 15% higher than HD-FF LTE-NB. Power supply design requirements are the most rigid for LTE-M.

Note: The end product's power supply and thermal design must comply with the worst-case consumption level. This prevents nRF9160 from occasionally resetting which generates extra current consumption. It also helps reduce overhead in the LTE network connection. Too much overhead could cause the network operator to block the end product from the network.