PBCH Bandwidth Optimization for 5G Synchronization Search Time
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Solution Overview
Problem
In 5G systems, certain frequency bands that can use two types of subcarrier spacings (SCSs) lead to excessive time for user equipment (UE) to search for synchronization signals due to narrow bandwidths, potentially taking up to 15 minutes, which is unacceptable.
Innovation Solution
A method and device for processing physical broadcast channel (PBCH) bandwidth by determining if the current frequency band is of a preset type capable of using two SCSs, where the number of bits of PBCH information in the payload is reduced by 14-22 bits or the number of resource elements (REs) occupied by the demodulation reference signal (DMRS) in the synchronization signal block (SSB) is reduced, or both, to optimize bandwidth usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the number of bits of PBCH information in the payload is reduced, then the PBCH bandwidth is reduced and UE search time is decreased, but the information capacity is reduced
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the number of bits of PBCH information in the payload based on the frequency band type. For frequency bands capable of using two types of SCSs, the PBCH information bits are reduced by 14-22 bits (typically 18 bits), which reduces the bandwidth and UE search time while maintaining essential broadcast information functionality.
2Loss of time
If the number of REs occupied by DMRS in SSB is reduced, then the PBCH bandwidth is reduced and UE search time is decreased, but the demodulation reference signal resources are reduced
Solution Approach 1:
The patent applies parameter changes by adjusting the number of REs occupied by DMRS in SSB for frequency bands capable of using two types of SCSs. The DMRS resources are reduced by 24-48 REs (typically 36 REs), which reduces the bandwidth and UE search time while maintaining sufficient demodulation capability through optimized resource allocation.
3Loss of time
If the PBCH bandwidth is reduced for frequency bands using two SCSs, then the UE search time is decreased, but the coverage capability may be impacted
Solution Approach 1:
The patent applies local quality by implementing different PBCH bandwidth configurations for different frequency band types. For frequency bands capable of using two types of SCSs, the bandwidth is reduced with fewer PBCH information bits and/or fewer DMRS REs. For other frequency bands, the standard bandwidth configuration is maintained, ensuring coverage capability is preserved where needed while optimizing search time where applicable.
Data Source
AI summary
A PBCH bandwidth processing method includes: determining whether a current frequency band is a preset type of frequency band, the preset type of frequency band being capable of using two subcarrier spacings (SCSs); if the current frequency band is the preset type of frequency band, reducing the number of PBCH information bits comprised in a load in a PBCH corresponding to the current frequency band and maintaining the number of resource elements (REs) occupied by a demodulation reference signal (DMRS) in a synchronization signal block (SSB) corresponding to the current frequency to be unchanged, or maintaining the number of PBCH information bits comprised in the load in the PBCH corresponding to the current frequency band to be unchanged and reducing the number of REs occupied by the DMRS in the SSB corresponding to the current frequency band.