Hierarchical NR Satellite Beam Timing for Lower SSB Monitoring Load
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Solution Overview
Problem
In non-terrestrial communication networks using New Radio (NR) technology, satellites transmit multiple beams, leading to high power consumption and difficulty in maintaining cell coverage due to limited transmission power when terminals need to monitor all synchronization signal blocks (SSBs) for narrow beams, especially in hierarchical beam structures.
Innovation Solution
A method and apparatus for beam management in a communication system that utilizes a hierarchical beam structure, where transmission timings for wide and narrow beams are configured differently, allowing terminals to receive synchronization signal blocks (SSBs) efficiently by identifying and accessing cell access information from transmission timing information, reducing unnecessary power consumption and improving reception performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the satellite transmits multiple narrow beams to cover the entire cell area, then the cell coverage is improved, but the terminal power consumption increases due to monitoring all SSBs for all narrow beams
Solution Approach 1:
The patent divides the cell into multiple local cells, each covered by a wide beam, and further divides local cells into sub-cells covered by narrow beams. This hierarchical segmentation allows terminals to first identify wide beams through initial SSB reception, then selectively monitor narrow beams only within identified local cells, reducing the total number of SSBs terminals must monitor while maintaining comprehensive coverage
Solution Approach 2:
The patent implements preliminary action by having the terminal first receive and identify wide beams (first SSBs) before attempting to receive narrow beams (second SSBs). The terminal uses transmission timing information to first establish connection with a wide beam, then selectively monitors narrow beams only if the wide beam reception is successful. This preliminary identification step prevents terminals from unnecessarily monitoring all narrow beam SSBs across the entire cell
2Reliability
If the satellite simultaneously transmits wide beams and narrow beams, then the reception performance is improved, but it becomes difficult to maintain conventional cell coverage due to limited transmission power
Solution Approach 1:
The patent segments the transmission hierarchy into wide beams for cell-level coverage and narrow beams for local cell coverage. Wide beams are transmitted with higher power to ensure broad coverage and reliable initial access, while narrow beams transmit additional SSBs only within identified local cells. This segmentation allows the system to maintain conventional cell coverage through wide beams while enhancing reception performance through targeted narrow beam transmissions
Solution Approach 2:
The patent applies local quality by transmitting narrow beams with enhanced signal quality only in specific local cells where wide beams are successfully received, rather than uniformly across the entire cell. This allows concentrated power allocation to narrow beams in identified areas, improving reception performance locally without sacrificing overall cell coverage maintained by wide beams
3Loss of energy
If the satellite deactivates transmission of some SSBs for wide beams, then the transmission power is saved, but the cell coverage may be compromised
Solution Approach 1:
The patent uses preliminary action by transmitting wide beam SSBs first as a preliminary step before narrow beam SSBs. The satellite transmits a reduced set of wide beam SSBs that provide initial coverage, then conditionally transmits narrow beam SSBs only in local cells where wide beams are successfully received. This preliminary wide beam transmission ensures minimum cell coverage is maintained while saving power by avoiding redundant SSB transmissions in areas not covered by wide beams
Data Source
AI summary
An operation method of a terminal in a communication system may comprise: receiving, from a satellite, transmission timing information including information on a first transmission timing of a first SSB of each of at least one local cell and information on second transmission timings of second SSBs of sub-cells belonging to each of the at least one local cell; identifying the first transmission timing of the first SSB and the second transmission timings of the second SSBs based on the transmission timing information; attempting to receive the second SSBs when the first SSB is received at the first transmission timing; acquiring cell access information from the second SSBs by receiving the second SSBs; and accessing the satellite by using the acquired cell access information.