PDCCH stands for Physical Downlink Control Channel. It is a channel used in LTE and 5G NR systems to carry Downlink Control Information (DCI). DCI is the information that tells the user equipment (UE) how to receive and transmit data on the physical channels. For example, DCI can indicate the resource allocation, modulation, coding, and hybrid-ARQ information related to the data channels.
PDCCH is significant in telecom networks because it enables efficient and flexible communication between the base station and the UE. PDCCH can support various use-cases, scenarios, and requirements of 5G systems, such as enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine type communications (mMTC). PDCCH can also support beamforming, which is a technique to improve the signal quality and coverage by directing the radio waves towards the intended direction.