Frequency Domain Configuration for SS/PBCH Block

Introduction

In 5G NR, the synchronization signal/physical broadcast channel (SS/PBCH) block is used for cell synchronization and system information broadcast. The SS/PBCH block is transmitted on the downlink channel and consists of two parts: the synchronization signal (SS) and the physical broadcast channel (PBCH). The frequency domain configuration for the SS/PBCH block is critical to ensure efficient and reliable communication between the base station and user equipment (UE). In this article, we will discuss the technical aspects of the frequency domain configuration for the SS/PBCH block in 5G NR.

Frequency Domain Structure of SS/PBCH Block

The frequency domain structure of the SS/PBCH block is defined by the system bandwidth and subcarrier spacing. The SS/PBCH block is transmitted on the downlink channel, with the SS and PBCH transmitted in separate frequency resources. The frequency domain configuration for the SS/PBCH block ensures that the SS and PBCH are transmitted in frequency resources that are widely separated to avoid interference.

In 5G NR, the system bandwidth is defined by the number of resource blocks (RBs) allocated to the downlink channel. The system bandwidth can be 5 MHz, 10 MHz, 15 MHz, 20 MHz, 25 MHz, 30 MHz, 40 MHz, 50 MHz, 60 MHz, 70 MHz, 80 MHz, 90 MHz, 100 MHz, 200 MHz, 400 MHz, or 800 MHz. The subcarrier spacing is defined by the frequency distance between two adjacent subcarriers, and can be 15 kHz, 30 kHz, 60 kHz, or 120 kHz.

The SS is transmitted in a specific frequency domain resource, which depends on the system bandwidth. The frequency domain resource for the SS is determined by the physical cell identity group (PCIG), which is indicated by the primary synchronization signal (PSS). The PCIG is a group of cells that share the same physical layer characteristics, such as the same subcarrier spacing and slot duration.

The PBCH is transmitted in a specific frequency domain resource, which depends on the system bandwidth and PCIG. The frequency domain resource for the PBCH is determined by the physical cell identity (PCI), which is indicated by the secondary synchronization signal (SSS). The PCI is a unique identifier for the cell and is used by the UE to identify and synchronize with the cell.

Frequency Domain Configuration for SS/PBCH Block in FDD Mode

In frequency division duplex (FDD) mode, the downlink and uplink transmissions are separated in frequency, with the base station and UE transmitting and receiving on different frequency bands. The frequency domain configuration for the SS/PBCH block in FDD mode must ensure that the SS and PBCH are transmitted on the downlink frequency band and received by the UE on the uplink frequency band.

The frequency domain configuration for the SS and PBCH in FDD mode is determined by the frequency range used for the downlink channel. The frequency range used for the downlink channel is divided into a number of frequency blocks, each of which is further divided into a number of resource blocks. The frequency domain configuration for the SS and PBCH is determined by the frequency block and resource block allocated to the downlink channel.

In FDD mode, the SS is transmitted in a specific frequency block and resource block, which depends on the system bandwidth and PCIG. The frequency block and resource block for the SS is determined by the PSS and PCIG, and is used by the UE to identify and synchronize with the cell.

The PBCH is transmitted in a specific frequency block and resource block, which depends on the system bandwidth, PCIG, and PCI. The frequency block and resource block for the PBCH is determined by the SSS, PCI, and the frequency block and resource block allocated to the downlink channel. The UE uses the PCI to identify the cell, and the frequency block and resource block to receive the PBCH.

Frequency Domain Configuration for SS/PBCH Block in TDD Mode

In time division duplex (TDD) mode, the downlink and uplink transmissions share the same frequency band and are separated in time. The frequency domain configuration for the SS/PBCH block in TDD mode must ensure that the SS and PBCH are transmitted in different time slots and received by the UE in the correct time slots.

In TDD mode, the downlink and uplink transmissions are separated into a number of time slots, with each time slot consisting of a number of symbols. The duration of a time slot and the number of symbols in a time slot depend on the subcarrier spacing.

The frequency domain configuration for the SS and PBCH in TDD mode is determined by the uplink-downlink (UL/DL) pattern and the slot format. The UL/DL pattern determines the number of time slots allocated for downlink transmission and uplink transmission, while the slot format determines the duration of the time slots and the number of symbols in a time slot.

In TDD mode, the SS is transmitted in a specific time slot and symbol, which depends on the UL/DL pattern and slot format. The time slot and symbol for the SS are determined by the PSS and PCIG, and is used by the UE to identify and synchronize with the cell.

The PBCH is transmitted in a specific time slot and symbol, which depends on the UL/DL pattern, slot format, and PCI. The time slot and symbol for the PBCH is determined by the SSS, PCI, UL/DL pattern, and slot format. The UE uses the PCI to identify the cell, and the time slot and symbol to receive the PBCH.

Conclusion

The frequency domain configuration for the SS/PBCH block is critical to ensure efficient and reliable communication between the base station and UE in 5G NR. The frequency domain structure of the SS/PBCH block is defined by the system bandwidth and subcarrier spacing, and the SS and PBCH are transmitted in separate frequency resources to avoid interference.

In FDD mode, the frequency domain configuration for the SS/PBCH block is determined by the frequency block and resource block allocated to the downlink channel, while in TDD mode, the frequency domain configuration is determined by the UL/DL pattern and slot format. The SS and PBCH are transmitted in specific frequency blocks, resource blocks, time slots, and symbols, which are determined by the PSS, SSS, PCIG, and PCI. The UE uses these parameters to identify and synchronize with the cell, and to receive the system information broadcast by the base station.