NR-PBCH Demodulation Using SSS as Reference Signal
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Solution Overview
Problem
In New Radio (NR) systems, the disparity in bandwidth between the Physical Broadcast Channel (PBCH) and synchronization signals makes the secondary synchronization signal (SSS) unsuitable for PBCH demodulation, and the absence of a common reference signal (CRS) complicates accurate channel estimation for NR-PBCH demodulation.
Innovation Solution
A method involving the use of the primary synchronization signal (PSS) and SSS, where the received SSS is used as a reference signal for demodulation, and NR-PBCH demodulation reference signals (DMRS) are interleaved with data and associated with a synchronization signal block (SSB) index to improve randomization in the synchronization process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If SSS is used as reference signal for PBCH demodulation in NR, then frequency correlation is lost due to bandwidth disparity, but in LTE SSS could serve as reference signal
Solution Approach 1:
The patent introduces a new demodulation reference signal (DMRS) specifically designed for NR-PBCH that serves as an intermediary reference signal. This DMRS is frequency-matched to the NR-PBCH bandwidth and positioned within the same resource blocks, acting as a mediator that enables accurate channel estimation without relying on the bandwidth-mismatched SSS.
2Reliability
If CRS is used for PBCH demodulation in LTE, then channel estimation is improved, but NR eliminates CRS to minimize always-on signals
Solution Approach 1:
The patent extracts the essential function of CRS (providing reference signals for channel estimation) and separates it from the always-on signal structure. By creating a dedicated DMRS that is only transmitted when NR-PBCH is transmitted, the patent removes the need for continuous CRS transmission while maintaining demodulation capability, thus reducing device complexity and power consumption.
Solution Approach 2:
The NR-PBCH structure becomes self-sufficient by incorporating its own dedicated DMRS within the same resource blocks. This self-service approach eliminates dependency on external reference signals like CRS or SSS, allowing the system to maintain reliable demodulation performance without requiring additional always-on signaling infrastructure.
3Quantity of substance
If NR-PBCH occupies 24 RBs while SSS occupies 12 RBs, then bandwidth capacity is increased, but frequency correlation for reference signal purposes is lost
Solution Approach 1:
The patent applies local quality by positioning DMRS specifically within the 24 RBs allocated for NR-PBCH transmission. The reference signals are distributed across the actual bandwidth being used, ensuring that channel estimation is performed locally within the relevant frequency range rather than relying on extrapolation from a narrower SSS bandwidth.
Data Source
AI summary
A method and apparatus are disclosed for demodulating a NR-PBCH signal. The method may comprise receiving a primary SS and an SSS. The received SSS signal may be used as a reference signal to detect demodulation reference signals of the NR-PBCH. These demodulation reference signals may be interleaved with data on the NR-PBCH. In one method, the NR-PBCH DMRS are associated with an SSB index in an effort to improve randomization in the synchronization process. The NR-PBCH payload may be demodulated using the PSS and/or SSS and the DMRS. In one embodiment, the NR-PBCH DMRS may mapped to DMRS REs on a frequency first and time second mapping basis.