Satellite 4G/5G Random Access Using Base-Station Timing Advance
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Solution Overview
Problem
Existing 4G and 5G satellite systems face challenges in random access procedures due to large time delays and uncertainties caused by satellite altitude and motion, which are not effectively addressed by existing terrestrial methods, particularly for devices without Global Navigation Satellite System (GNSS) capabilities, leading to inefficiencies and increased power consumption.
Innovation Solution
Implement GNSS-independent and GNSS-assisted random access methods that determine minimum and differential delays without relying on GNSS receivers, using ephemeris information, to synchronize user equipment with satellite systems, including methods for various satellite orbits and base station adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If terrestrial 4G/5G random access procedures are used in satellite systems, then device compatibility is maintained, but timing synchronization fails due to large and variable time delays
Solution Approach 1:
The patent changes the timing parameters of the random access procedure by introducing a timing advance mechanism that compensates for satellite propagation delays. The base station calculates the round-trip time delay and adjusts the uplink timing accordingly, allowing terrestrial protocols to work in satellite environments with vastly different propagation characteristics.
Solution Approach 2:
The patent implements dynamic timing adjustment where the timing advance value is continuously updated based on measured delay variations. This allows the system to adapt to changing satellite positions and orbital mechanics while maintaining synchronization, transforming a static terrestrial protocol into a dynamic satellite-compatible procedure.
2Measurement precision
If GNSS receivers are added to all user equipment for timing synchronization, then timing accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent introduces the base station as an intermediary that performs timing measurement and compensation functions. Instead of requiring each user equipment to independently measure and compensate for timing delays using GNSS, the base station centralizes this function, receiving uplink signals, calculating delays, and providing timing advance commands to synchronize users.
Solution Approach 2:
The patent enables the system to self-synchronize without external GNSS infrastructure by having the base station measure actual signal propagation delays and automatically calculate timing advance values. The system uses its own transmitted signals as reference, eliminating the need for external timing sources at the user equipment.
3Reliability
If GNSS receivers are continuously operated for timing, then timing synchronization is maintained, but power consumption increases
Solution Approach 1:
The patent implements periodic timing updates where the base station provides timing advance commands at intervals rather than requiring continuous GNSS operation. User equipment can enter low-power states between updates, knowing that timing synchronization will be maintained through these periodic corrections from the base station.
4Measurement precision
If ephemeris information is transmitted to all user equipment for timing calculation, then timing accuracy improves, but downlink overhead increases
Solution Approach 1:
The patent extracts the timing measurement function from user equipment and concentrates it at the base station. Instead of providing ephemeris data to all users so they can independently calculate timing, the base station directly measures propagation delays from received signals and provides only the necessary timing advance commands, eliminating redundant information transmission.
Data Source
AI summary
Systems and methods for communication in 4G and 5G broadband satellite networks are provided. The disclosed methods include Global Navigation Satellite System (GNSS)-independent methods, and GNSS assisted methods that do not require transmission of satellite ephemeris information from a base station to user equipment.