NR-PBCH DMRS Sequence Phase Rotation for SS Block Position Indication
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Solution Overview
Problem
In the New Radio (NR) system, the position relation between a synchronization signal block (SS block) and a system frame cannot be indicated, leading to difficulties in accurately detecting the SS block within the transmission resources of a system frame.
Innovation Solution
A method for configuring a demodulation reference signal (DMRS) sequence of the physical broadcast channel (PBCH) to indicate the position relation between the SS block and the system frame, using phase rotation information, mapping modes, shifts, or gold sequences, allowing the terminal to determine the correct position relation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the DMRS sequence is used only for demodulation reference, then the demodulation function is achieved, but the position relation indication between SS block and system frame is lost
Solution Approach 1:
The DMRS sequence is configured to serve dual purposes: (1) as a demodulation reference signal for channel estimation and PBCH demodulation, and (2) as an indication carrier for the position relation between SS block and system frame. By making the DMRS sequence multi-functional, the patent avoids adding separate indication channels while preserving all necessary information.
Solution Approach 2:
The patent changes parameters of the DMRS sequence (such as sequence initialization values, cyclic shifts, or phase rotations) to encode different position relation indications. By varying these parameters based on the SS block position, the system can convey timing information without increasing overall signal complexity.
2Loss of time
If the SS block position information is transmitted through PBCH payload only, then complete information can be conveyed, but terminal cannot obtain position information before PBCH decoding
Solution Approach 1:
The patent embeds position relation indication information in the DMRS sequence before PBCH decoding is required. The terminal can extract this information from the DMRS sequence in advance, enabling early determination of SS block position without waiting for the time-consuming PBCH decoding process.
Solution Approach 2:
The DMRS sequence acts as an intermediary that carries position indication information independently of the PBCH payload. This intermediary channel allows the terminal to obtain critical timing information through simple DMRS detection rather than requiring full PBCH decoding.
3Loss of information
If 2 bits or 3 bits are carried through DMRS sequence, then partial time index information is transmitted, but the indication of first or last 5 ms position is incomplete
Solution Approach 1:
The patent extends the information capacity of the DMRS sequence by utilizing additional dimensions such as different sequence groups, cyclic shift values, or phase rotation angles. This allows encoding of complete position relation information (including first/last 5 ms indication) within the existing DMRS resource framework without requiring more bits.
Data Source
AI summary
A method for transmitting a DMRS of a physical broadcast channel, a network device and a terminal for performing the method are provided. The method includes: configuring a demodulation reference signal DMRS sequence of a new radio physical broadcast channel NR-PBCH, where the DMRS sequence is configured to indicate a position relation between a synchronization signal block to which the NR-PBCH belongs and a system frame where the SS block is located; and transmitting the DMRS sequence of the NR-PBCH to a terminal. The configuring the DMRS sequence of the NR-PBCH includes: configuring phase rotation information of the DMRS sequence of the NR-PBCH. The position relation between the SS block to which the NR-PBCH belong and the system frame where the SS block is located includes: the SS block being located in a first or last 5 ms of the system frame where the SS block is located.