5G Downlink Signals, Channels and Top Interview Questions
Part of Interview Preparation. The articles below are meant to be read in order.
5G NR Downlink Channel Mappings: The Map You Need Before Anything Else
How logical, transport and physical channels fit together in the 5G NR downlink, and why NR needs fewer physical channels than LTE.
5G NR Synchronisation Signals (PSS and SSS): How a Phone Finds a Cell From Nothing
PSS and SSS explained from the UE's point of view: what each signal gives the receiver, how the PCI is built from them, and why NR has 1008 cell identities.
5G NR PBCH and the MIB: The 32 Bits That Unlock a Cell
What the PBCH carries, why every bit in the MIB is there, how the physical layer adds timing bits, and how the UE goes from PBCH to SIB1.
5G NR SS/PBCH Blocks and Bursts: Beams, Timing and the 5 ms Window
How PSS, SSS and PBCH are packaged into one SSB, how multiple SSBs form a burst set for beam sweeping, and the Case A–E timing patterns.
5G NR PDCCH Demystified: CORESETs, Search Spaces and Every DCI Format
A clarity-first walk through the PDCCH: how control channels are built from CCEs, what a CORESET and a search space really are, how SIB1's search space is derived from the MIB, and what each DCI format (0_0, 0_1, 1_0, 1_1, 2_0–2_3) actually does.
5G NR PDSCH From Bits to Resource Elements: MCS, TBS, Processing, Allocation and the Four Special Cases
A step-by-step tour of the PDSCH: how the MCS tables work, how the transport block size is computed, the physical-layer processing chain, frequency and time allocation types, resource block bundling, pre-emption, reserved resources and slot-aggregation repetition.
5G NR Downlink Reference Signals: DM-RS, CSI-RS, TRS and PT-RS Without the Headache
What each downlink reference signal is for, where it sits, and how NR replaced LTE's always-on CRS with four purpose-built signals: DM-RS (for PBCH, PDCCH and PDSCH), CSI-RS, TRS and PT-RS.