the starting OFDM symbol and the time duration. This configuration provided by the network can be device-specific and the CORESET defines the cell search space for the device to use to monitor the control channels. This is the main difference between it and LTE. In LTE, the control region was located at the first three OFDM symbols and was shared between all users in the service area. In NR, the control region Downlink physical channels and signals is defined specifically for each device. Additionally, this adds flexibility to resource control allocation and allows devices not capable of running at maximum bandwidth to operate. A device with a smaller bandwidth support can be also configured so that the CORESET spans only on supported bandwidth. Group-Common PDCCH A special case of PDCCH is a Group-Common PDCCH. This is a PDCCH intended for a group of devices. First, it carries the Slot Format Indicator (SFI). As discussed in the previous chapters, the SFI indicates which OFDM symbols in a slot are configured as downlink, uplink, or flexible. Second, it carries the Preemption Indicator (PI). This is related to low-latency traffic. We will discuss this further in this chapter. So far, we have covered the control channel for the downlink. Now, let's analyze the shared channel. The PDSCH Now that we have briefly described the PDCCH, which is mainly used for scheduling decisions required for the downlink data channel, the PDSCH, let's have a look at the PDSCH. The general aspects of this channel are similar to LTE. It carries user data. The modulated symbols are mapped across layers associated with the codeword first, followed by subcarriers, and lastly OFDM symbols. The supported modulations in NR are QPSK, 16 Quadrature Amplitude Modulation (QAM), 64 QAM, and 256 QAM. PDSCH is rate-matched around Synchronization Signal Blocks (SS blocks) and CORESETs in case its transmission overlaps with them. If there is an overlap with an SS block, the network can specifically indicate to a device whether the PDSCH is rate-match