In this course, we will discuss the 5G Initial Access Procedure and Parameters in detail. When we want to connect a UE to a 5G network, it has to synchronize in downlink as well as in uplink. Downlink synchronization is obtained after successfully decoding SSB, In order to establish uplink synchronization and RRC connection, UE has to perform RACH random access procedure. We will cover the following topics:

• The Structure of PRACH in detail, covering the PRACH time domain and frequency domain position in the resource grid. We will also discuss the short and long preamble, their length, and associated information. Different PRACH formats available in 5G and their respective details will be covered. We will also see the uplink synchronization process and see the respective signaling.

• UE selects a Preamble randomly from a pool of preambles shared with other UE. The gNodeB uses a contention resolution mechanism to handle this type of access request. The result is random and not all Random Access succeeds. The second module will cover the Contention-Based Random Access (CBRA)and Contention-Free Random access (CFRA) procedure.

• DL Synchronization and Cell/Network Selection: Cell search is the procedure by which a UE acquires time and frequency synchronization with a cell and decodes the Cell ID of that cell. In 5G NR, Cell search concept is similar to what it is in LTE in terms of decoding Primary Sync Signal (PSS) and Secondary Sync Signal (SSS) to the Physical Cell ID (PCI). following which PLMN selection and cell selection are performed.