extend the data transmission to all OFDM symbols. For eMTC and 5G, the PRB cannot be perfectly aligned due to the presence of a DC subcarrier in eMTC. As a result, for 15 kHz subcarrier spacings (SCSs), an additional 5G PRB will be needed to accommodate eMTC. Several potential enhancements can be considered, for example, by puncturing the last subcarrier in eMTC SO that only six 5G PRBs would be needed. Note that this may be done via implementation with the eMTC performance impact considered. Reduction of Cell Reference Signals (CRSs) on part of the bandwidth, for example, to transmit CRS only on narrowband(s) in which the UE performs measurements. This would reduce the number of PRBs that are marked as reserved and therefore cannot be used by 5G. As described above, eMTC and NB-IoT are used to support 5G mMTC services. The technologies continue to evolve and improve with new enhancements. In 3GPP Release 15, the following key enhancements were added: Reduced UE Power Consumption - Wake-up signal for idle mode paging - This is a new physical signal that must be detected prior to monitoring the control channel during idle mode paging. This is illustrated in Figure 14.26. The wake-up signal is an ON/OFF signal that is much shorter than the control channel. It allows the UE to quickly detect whether or not there is an upcoming control channel. If not, it can quickly return to sleep mode. Furthermore, a wake-up receiver can be used where most components of the device stay in sleep mode and therefore requires only a very small amount of power to run. This can significantly reduce UE power consumption. Early data transmission during the random access procedure (only uplink specified in Release 15) - A UE can transmit uplink data (up to 1000 bits) during the random access procedure. This can significantly reduce the latency and overhead associated with small data transmission and also UE power consumption. - Uplink HARQ-ACK feedback for early termination (eMTC only) - Early termina- tion supported for (1) uplink data tr