5G NR MIMO Explained: Transport Block to Antenna Ports in 30 Minutes

If you've ever been confused about why we have antenna ports, layers, and rank (and why they're all different things), this video walks through the full RAN pipeline step-by-step: TB → CW → Layer Mapping → Digital Precoding → Logical Antenna Ports → Beamforming → Physical Antennas → UE. You'll learn: ✔ What a Transport Block (TB) is and how it becomes a Codeword (CW) ✔ Why HARQ operates at the TB level (not CW) ✔ When NR uses 1 TB vs 2 TBs (rank 1–4 vs rank 5–8) ✔ How layer mapping distributes symbols across spatial streams ✔ What the precoding matrix W actually does ✔ The difference between physical and logical antenna ports ✔ How DMRS, CSI-RS, and SRS fit into the picture ✔ Why rank ≤ min(Tx, Rx) — and why it depends on the channel ✔ How UE feedback (RI, PMI, CQI) closes the loop ⏱ CHAPTERS 00:00 Intro — why this chain exists 01:18 RAN signal processing chain 04:45 Stage 1: Transport Block (TB) 07:23 Stage 2: Codeword (CW) — CRC, LDPC, rate matching, scrambling 08:10 TB → CW mapping 08:17 Stage 3: Layer Mapping 10:58 Stage 4: Digital Precoding 13:05 PMI and the Type I / Type II codebooks 15:38 Stage 5: Logical Antenna Ports — the 3GPP abstraction 20:17 Stage 6: Analog Beamforming & Physical Antennas 21:57 Key takeaways 📝 Full written version (Medium):   / why-do-we-have-antenna-ports-layers-and-ra...   💬 Questions? Drop them in the comments — next videos will cover uplink MIMO, CSI Type II codebooks, and massive MIMO calibration. 👍 If this helped, like and subscribe for more RAN / 5G deep dives. #5G #5GNR #MIMO #Telecommunications #RAN #Wireless #AntennaPorts #BeamForming #MassiveMIMO #5GArchitecture #WirelessEngineering