CHAPTER 5
Coverage Techniques
The following section provides background information and technical insights into many of the techniques used to provide the coverage enhancement for the LTE-M specification.
5.1 TX POWER
For every dB the TX power is increased, there is a 1 dB increase in MCL. As mentioned in the MCL section, LTE-M supports two UE Power Classes of PA; Class 3 PA 23 dBm, and Class 5 PA 20 dBm, so a Class 3 UE would have a 3 dB better UL MCL. Although increasing UE TX power above 23 dBm sounds like an easy method to gain coverage, there are several issues in doing so – increased cost, regulatory issues (e.g. specific absorption limits), increased inter-cell interference, and peak current issues. In fact, for IoT devices the trend is to lower the TX power to make the PA more practical to be integrated and thus reduce the cost. This is why the 20 dBm Class 5 UE was added as part of the LTE-M work.
Fact
CAT-M1 supports two UE Power classes: 23 dBm Class 3 and 20 dBm Class 5.
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LTE-M Coverage Enhancement Mode A & B
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Coverage Analysis
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LTE-M Coverage Enhancement Mode A & B
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Coverage Analysis