Category: 5G Air Interface

5G NR Physical Layer Channels: Physical Broadcast Channel (PBCH)

5G Air Interface

To enable devices to find a cell when entering a system, as well as to find new cells when moving within the system, a synchronization signal consisting of two parts, the Primary Synchronization Signal (PSS) and the Secondary Synchronization Signal (SSS), is periodically transmitted on the downlink from each NR cell.

The PSS/SSS, together with the Physical Broadcast Channel (PBCH), is jointly referred to as a Synchronization Signal Block or SS block

The PSS is transmitted in the first OFDM symbol of the SS block and occupies 127 subcarriers in the frequency domain. The remaining subcarriers are empty.

• The SSS is transmitted in the third OFDM symbol of the SS block and occupies the same set of subcarriers as the PSS. There are eight and nine empty subcarriers on each side of the SSS.

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5G NR Control Resource Set (CORESET)

5G Air Interface

The CORESET configuration obtained from the PBCH also defines and activates the initial bandwidth part in the downlink.

The initial active uplink bandwidth part is obtained from the system information scheduled using the downlink PDCCH.
Once connected, a device can be configured with up to four downlink bandwidth parts and up to four uplink bandwidth parts for each serving cell.

On each serving cell, at a given time instant one of the configured downlink bandwidth parts is referred to as the active downlink bandwidth part for the serving cell and one of the configured uplink bandwidth parts is referred to as the active uplink bandwidth part for the serving cell.

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5G: Bandwidth Part

5G Air Interface

A bandwidth part is characterized by a numerology (subcarrier spacing and cyclic prefix) and a set of consecutive resource blocks in the numerology of the BWP, starting at a certain common resource block.

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5G NR numerology

5G Air Interface

The 5G NR numerology for the carrier is similar to LTE includes subcarrier spacing (SCS) and CP.

15 kHz Subcarrier Spacing (SCS) is not enough and multiple larger SCS values with 2^μ × 15 kHz, where μ = 0, 1, 2, 3, 4 were introduced for the mobility requirement supporting up to 500 km/h.

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5G Frequency Bands

5G Air Interface

Frequency bands within the scope of Release 15 in 3GPP are divided into two frequency ranges:

Frequency range 1 (FR1) includes all existing and new bands below 6 GHz.
Frequency range 2 (FR2) includes new bands in the range 24.25 – 52.6 GHz.
The frequency bands where NR will operate are in both paired and unpaired spectra, NR supports both FDD and TDD operation
The Carrier bandwidth available in frequency ranges FR1 and FR2 are given in the table:

Release 15 of the 3GPP specifications for NR includes 26 operating bands in frequency range 1 and three in frequency range 2.

Bands Defined by 3GPP for NR in Frequency Range 1:
Bands Defined by 3GPP for NR in Frequency Range 2

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