DMRS Position Configuration for Beamformed Wireless Systems
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Solution Overview
Problem
In next-generation wireless communication systems, particularly in 5G networks, beamforming is used to mitigate mutual coupling losses in millimeter wave systems, but this results in significant overhead due to beam sweeping, which transmits identical signals in different directions, necessitating efficient alignment of physical downlink shared channels (PDSCHs) with synchronization blocks (SS blocks) and transmission of remaining system information (RMSI) on the same beam as SS blocks.
Innovation Solution
The DMRS position is signaled in the downlink control information, allowing flexibility in configuration, and is fixed to the 4th OFDM symbol in slots with SS blocks to maximize beam reuse, enabling efficient multiplexing of RMSI and SS block transmissions within the same RF beam, thereby reducing overhead and increasing beam reuse by up to 33%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If beam sweeping is used to mitigate mutual coupling losses in millimeter wave systems, then communication reliability is improved, but overhead increases significantly
Solution Approach 1:
The patent combines synchronization signal block (SSB) transmissions with physical downlink shared channel (PDSCH) transmissions carrying remaining system information (RMSI) into the same beamformed transmission. This merging allows the system to utilize the beam sweeping process more efficiently, where beams are swept for synchronization purposes and simultaneously carry system information, thereby reducing the need for separate dedicated RMSI transmissions and reducing overall overhead while maintaining communication reliability
Solution Approach 2:
The patent enables the beamformed synchronization signal blocks to serve multiple functions: they provide synchronization signals for cell search and initial access, and simultaneously carry remaining system information (RMSI) through the multiplexed PDSCH transmission. This multi-functionality allows the same beam sweeping infrastructure to serve both synchronization and system information delivery purposes, reducing overhead without compromising reliability
2Area of stationary object
If identical signals are transmitted in different directions for beam sweeping, then coverage is improved, but transmission efficiency deteriorates
Solution Approach 1:
The patent merges the transmission of synchronization signals and system information into a single beamformed transmission process. Instead of sweeping beams for synchronization and then separately transmitting system information, the system combines these functions so that each swept beam simultaneously delivers synchronization signals and carries RMSI, thereby improving transmission efficiency while maintaining comprehensive coverage
Solution Approach 2:
The patent performs system information transmission during the beam sweeping process itself, rather than after synchronization is established. By preliminarily incorporating RMSI transmission into the synchronization beam sweeping phase, the system eliminates the need for additional dedicated transmission resources, thereby improving overall transmission efficiency while maintaining full coverage
Data Source
AI summary
Various embodiments disclosed herein provide for efficient configuration of demodulation reference signals in beamformed wireless communications systems. In an embodiment, the transmitter can signal the location of demodulation reference signals (DMRS) by including an indicator bit in downlink control information indicating which DMRS scheme is used in the transmission. A first DMRS scheme can let the user equipment (UE) device know that the DMRS position for the PDSCH carrying the RMSI is as signaled on the master information block (MIB)—referred to as PDSCH Mapping Type A. A second DMRS scheme can let the UE device know that the DMRS position for the PDSCH carrying the RMSI is the first orthogonal frequency division multiplexing (OFDM) symbol of said PDSCH allocation—referred to as PDSCH mapping type B).