How does resource allocation differ between LTE and 5G NR?

LTE has one fixed numerology (15 kHz, 12 subcarriers per RB) and schedules on 1 ms subframes. NR keeps the 12-subcarrier RB but lets subcarrier spacing scale as 15 × 2^μ kHz, schedules per slot (1 ms / 2^μ), and confines a UE to a Bandwidth Part rather than the whole carrier. That flexibility lets NR mix latency profiles and bandwidths on one carrier in a way LTE cannot.

What is a Bandwidth Part (BWP) and does LTE have one?

A BWP is a contiguous subset of the carrier’s PRBs with its own numerology that a UE is configured to operate in, so a device need not tune to the full channel bandwidth. LTE has no equivalent — a UE always uses the whole system bandwidth. BWPs save UE power and let one NR carrier serve narrowband and wideband devices side by side.

Is the resource block the same size in LTE and NR?

A resource block is 12 subcarriers wide in both, but its frequency span differs because the subcarrier spacing differs. In LTE that is always 180 kHz (12 × 15 kHz); in NR a 30 kHz RB spans 360 kHz and a 120 kHz RB spans 1.44 MHz. NR also defines the RB purely in the frequency domain, whereas LTE ties it to a 0.5 ms slot.

4G vs 5G Resource Allocation

Visual side-by-side comparison of how LTE and 5G NR lay out resources in time and frequency. Toggle numerology, inspect BWP, and see why NR is so much more flexible.

NR Subcarrier spacing

Slot = 0.5 ms · 2 slots/subframe

LTE PDCCH symbols

5G NR optionsShow Bandwidth Part (BWP)

LTE Resource Block

SCS 15 kHz · 1 ms subframe

REs per slot = 12 × 7 = 84 · per subframe = 168 · fixed 15 kHz SCS

5G NR Slot

SCS 30 kHz · slot 0.5 ms

REs per slot = 12 × 14 = 168 · SCS 15 × 2^μ kHz · slot = 1/2^μ ms

Key differences at a glance

Slot duration: LTE is fixed at 0.5 ms per slot (2 slots / 1 ms subframe). NR scales with numerology — 0.5 ms at 30 kHz SCS.
Numerology: LTE uses only 15 kHz SCS. NR supports 15/30/60/120/240 kHz and can mix numerologies in the same carrier.
BWP: NR defines Bandwidth Parts so a UE can live in a narrow slice of a wide carrier to save power. LTE has no such concept — UEs always monitor the full carrier.
Mini-slots: NR can schedule a transmission over just 2, 4 or 7 symbols for URLLC. LTE schedules whole subframes only.
PDCCH position: LTE PDCCH occupies the first 1–3 symbols of every subframe, across the full bandwidth. NR uses CORESETs — configurable in time and frequency — giving much more scheduling flexibility.

Feature comparison

Feature	LTE (4G)	5G NR
Subcarrier spacing (SCS)	15 kHz (fixed)	15 / 30 / 60 / 120 / 240 kHz
Symbols per slot	7 (normal CP)	14 (normal CP)
Slot duration	0.5 ms	1 / 2^μ ms (e.g. 0.5 ms at 30 kHz)
Min. scheduling unit	1 subframe (1 ms, 2 slots)	1 slot, or mini-slot (2/4/7 sym)
Radio frame duration	10 ms (10 subframes)	10 ms (10 × 2^μ slots)
Mixed numerology	Not supported	Supported — different SCS in same carrier
Resource allocation unit	Resource Block (12 SC × 7 sym × 2 slots)	PRB (12 SC × 14 sym) within a BWP

About resource allocation in LTE vs 5G NR

LTE was designed around a single numerology — 15 kHz SCS, 1 ms subframes, 7-symbol slots under normal cyclic prefix. Every UE in the cell listens to the first 1–3 symbols of each subframe for PDCCH across the full channel bandwidth, then decodes its PDSCH in the rest. Simple and predictable, but rigid: a UE on a 100 MHz carrier would waste power monitoring frequencies it doesn't need, and there was no way to shorten a transmission for ultra-low latency.

5G NR replaced that with a scalable numerology (μ = 0 to 4), slots of 14 OFDM symbols, configurable CORESETs for PDCCH, Bandwidth Parts so a UE can operate on a narrow slice of a wide carrier, and mini-slots for URLLC. The fundamental RE-count per slot is the same (12 × 14 = 168), but the time and frequency elasticity is what enables eMBB, URLLC and mMTC to coexist on the same radio.

Related tools

How to use the 4G vs 5G Resource Allocation tool

Set the LTE side. Choose the LTE bandwidth to fix the RB count on the 15 kHz grid.
Set the NR side. Pick the NR numerology and bandwidth, and define a BWP to scope the UE.
Compare the grids. View RB size, slot length and scheduling unit side by side for both technologies.
Explore the differences. Change numerology or BWP to see how NR scheduling diverges from the fixed LTE structure.

Frequently asked questions

How does resource allocation differ between LTE and 5G NR?: LTE has one fixed numerology (15 kHz, 12 subcarriers per RB) and schedules on 1 ms subframes. NR keeps the 12-subcarrier RB but lets subcarrier spacing scale as 15 × 2^μ kHz, schedules per slot (1 ms / 2^μ), and confines a UE to a Bandwidth Part rather than the whole carrier. That flexibility lets NR mix latency profiles and bandwidths on one carrier in a way LTE cannot.
What is a Bandwidth Part (BWP) and does LTE have one?: A BWP is a contiguous subset of the carrier’s PRBs with its own numerology that a UE is configured to operate in, so a device need not tune to the full channel bandwidth. LTE has no equivalent — a UE always uses the whole system bandwidth. BWPs save UE power and let one NR carrier serve narrowband and wideband devices side by side.
Is the resource block the same size in LTE and NR?: A resource block is 12 subcarriers wide in both, but its frequency span differs because the subcarrier spacing differs. In LTE that is always 180 kHz (12 × 15 kHz); in NR a 30 kHz RB spans 360 kHz and a 120 kHz RB spans 1.44 MHz. NR also defines the RB purely in the frequency domain, whereas LTE ties it to a 0.5 ms slot.

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