4G LTE Resource Grid

Downlink Interactive PRB map FDD & TDD PCFICH · PHICH · PDCCH · PDSCH

A hands-on view of how the LTE downlink maps synchronization, broadcast, reference, and control channels onto individual resource elements. Tweak the parameters and watch the grid rebuild in real time. Companion to the 5G NR resource grid.

3GPP release & assumptions

Release: channel mapping follows 3GPP Release 17 (TS 36.211, 36.213, 36.331). The formulas used here are stable across Rel-8 through Rel-18 for everything implemented.

• PSS/SSS — primary and secondary synchronization signals in subframes 0 and 5 (TS 36.211 §6.11).
• PBCH — physical broadcast channel carrying the MIB in subframe 0, centred around DC (TS 36.211 §6.6).
• Cell RS — cell-specific reference signals for up to four antenna ports (TS 36.211 §6.10).
• PCFICH / PHICH / PDCCH — control region sized by CFI; PHICH groups derived from N_g and duration (TS 36.211 §6.7–6.8).
• PDSCH — data region in remaining OFDM symbols, rate-matched around control and reference REs.
• Not modelled: EPDCCH, CSI-RS (Rel-10+), DMRS for PDSCH, multi-cell ICIC, carrier aggregation.

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Configuration

Live

Duplexing mode

FDD TDD

TDD uplink/downlink configurationsignalled in SIB1

0 1 2 3 4 5 6

TDD special-subframe configurationsignalled in SIB1

0 1 2 3 4 5 6 7 8 9

MBSFN subframesignalled in SIB2

None 1 2 3 4 6 7 8 9

Channel bandwidthcarried in the MIB

1.4 MHz 3 MHz 5 MHz 10 MHz 15 MHz 20 MHz

Cyclic prefix

Normal Extended

Tx antenna port / number of ports

0 1 2 3 / 1 2 4

Physical-layer cell ID (0–503)recovered from PSS/SSS

Control format indicator (CFI)carried on PCFICH

1 2 3

CFI for TDD subframes 1 and 6carried on PCFICH

1 2

CFI for MBSFN subframecarried on PCFICH

1 2

PHICH Ng factorcarried in the MIB

1/6 1/2 1 2

PHICH durationcarried in the MIB

Normal Extended

Set marker at

None PCFICH PHICH PDCCH REG 0 1 2 3 REG 0 1 2 of mapping unit 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Logical Physical REG 0 1 2 3 4 5 6 7 8 of CCE REG

in subframe

0 1 2 3 4 5 6 7 8 9

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Resource Grid

Downlink · Live

View span:

Slot Subframe Frame

Zoom: 100%

Generated live from the configuration and 3GPP channel-mapping formulas. Each cell is a resource element (RE) colored by the channel it carries — hover to inspect.

Hover over any cell to inspect its channel, subframe, slot, symbol & subcarrier

About the 4G LTE downlink resource grid

The LTE downlink physical resource grid is a time–frequency lattice of resource elements (REs), grouped into physical resource blocks (PRBs) of 12 subcarriers × 1 slot. This tool draws the grid live from your configuration so you can see exactly which REs carry synchronization, broadcast, reference, and control signalling.

LTE downlink channels on the grid

PSS / SSS

Primary and secondary synchronization signals for cell search and frame timing (subframes 0 and 5).

PBCH

Physical broadcast channel carrying the Master Information Block (MIB) in the centre PRBs of subframe 0.

Cell RS

Cell-specific reference signals used for channel estimation, mapped per antenna port.

PCFICH

Physical control format indicator channel — signals how many OFDM symbols the control region spans (CFI).

PHICH

Physical hybrid-ARQ indicator channel — carries HARQ ACK/NACK for uplink grants.

PDCCH

Physical downlink control channel — carries DCI scheduling grants in CCEs built from REGs.

PDSCH

Physical downlink shared channel — user data in the remaining available REs.

Configurable parameters

Adjust duplex mode (FDD or TDD), channel bandwidth, cyclic prefix, CFI, PHICH configuration, cell ID, MBSFN subframes and antenna ports. The grid updates instantly and supports shareable links to any configuration. For 5G NR, see the companion 5G NR resource grid tool.