5G/6G Academy

5G/6G Academy

Telecom certifications · since 2009

RE Mapping Visualizer

Overlay PDSCH, DMRS, PTRS and CSI-RS on a 12 × 14 PRB resource element grid. Toggle any reference signal on or off, click a cell to inspect it, and watch the remaining PDSCH RE count — the starting point of a 5G NR Transport Block Size (TBS) calculation.

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PDSCH data
DMRS
PTRS
CSI-RS
Total REs
168
PDSCH REs
162
DMRS REs
6
PTRS REs
0
CSI-RS REs
0

About RE mapping

A 5G NR PRB carries 12 subcarriers × 14 OFDM symbols = 168 resource elements per slot. Before PDSCH data can occupy the grid, the gNB must first reserve REs for reference signals: DMRS for channel estimation, PTRS to track high-frequency phase noise in FR2, and CSI-RS for beam / channel-state measurement. Everything not reserved becomes available PDSCH RE.

The available PDSCH RE count feeds directly into the TBS (Transport Block Size) determination in TS 38.214 §5.1.3: NRE = min(156, N'RE) × nPRB, then Ninfo = NRE · R · Qm · ν, quantised to a TBS entry. Use this tool to build intuition for how much overhead each reference signal actually costs you.

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