As mentioned above, the determination of the coverage is not simply a matter of looking at block error rates.
For some channels, it is more appropriate to measure against an application level performance criterion so in this paper we also measured data speed and acquisition times.
Table 7 summarizes the performance results from the LLS evaluation at an MCL of 164 dB:
As can be seen from Table 7, not only is LTE-M capable of operating at an MCL of 164 dB but the performance in terms of data speed and acquisition time are very good. If the application can tolerate lower speeds and longer acquisition times, an MCL of beyond 164 dB can also be supported. The coverage balance of the LTE-M channels is also very good where there is at least one more repetition level available in the standard for all the LTE-M control channels. A key finding is that through LLS, all the LTE-M channels are well balanced and can realistically support a 164 dB MCL.
Through LLS, all the LTE-M channels are well balanced and can realistically support 164 dB MCL.
LTE-M can realistically provide 21.3 dB of gain which exceeds the 18 dB 3GPP target by 3.3 dB.
As mentioned, coverage performance can be expressed in MCL or gain. As shown in section 4.2, the baseline is at 142.7 dB MCL thus in terms of gain, considering that LTE-M supports 164 dB MCL, LTE-M can realistically provide 21.3 dB of gain relative to Release 12 LTE which exceeds the 18 dB target by 3.3 dB.
The key purpose of this paper was to determine the coverage provided by the LTE-M specification through LLS but there are other key performances indicators that can be evaluated. For example, battery life and the message delivery time at different MCL levels are additional performance indicators which are important. This work can serve as a basis for further study of those topics.