Satellite Uplink Access Channels with Timing-Advance Slot Search
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Solution Overview
Problem
Satellites face challenges in distinguishing uplink signals from user equipment devices due to limited output power levels and finite resources, leading to high processing burdens in identifying signals from multiple user devices.
Innovation Solution
User equipment devices transmit uplink data packets within a narrow time window synchronized to a satellite time reference, using timing advances to ensure packets arrive within a finite time slot, allowing the satellite to search for signals efficiently within this window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If satellites search for uplink signals from multiple user devices over all time, then signal identification completeness is improved, but processing resources and time consumption increase significantly
Solution Approach 1:
The system performs preliminary actions by pre-calculating and distributing timing advance information to user devices before actual signal transmission. Each device is provided with timing advance values that compensate for their specific path lengths to the satellite, enabling them to transmit signals at the correct time slots. This preliminary preparation allows the satellite to search for signals only within a narrow time window around the expected arrival time, dramatically reducing processing time while maintaining identification completeness.
Solution Approach 2:
The patent segments the search process into discrete time slots within a narrow time window. Instead of searching continuously over all time, the system divides the relevant search period into multiple time slots, each corresponding to a specific timing advance value. The satellite searches for signals in these segmented time slots, which reduces the total search duration while ensuring all possible user device signals are captured.
2Ease of operation
If user equipment devices transmit uplink signals simultaneously without timing coordination, then communication simplicity is improved, but signal distinguishability and processing burden increase
Solution Approach 1:
The network performs preliminary action by calculating and distributing timing advance values to each user device before transmission. These timing advance values are pre-computed based on the device's path length to the satellite and are provided to the device beforehand. This preliminary coordination eliminates the need for complex real-time synchronization protocols during actual transmission, maintaining operational simplicity while enabling effective signal processing.
Solution Approach 2:
The system changes the timing parameter of signal transmission by introducing timing advance adjustments. Instead of transmitting signals simultaneously at a fixed time, each device transmits at a different time offset (timing advance) that compensates for its specific path length. This parameter change creates time-separated signal arrivals at the satellite, improving distinguishability without significantly increasing processing complexity.
3Reliability
If satellites use larger time windows for signal reception, then signal capture completeness is improved, but processing resources and power consumption increase
Solution Approach 1:
The system performs preliminary action by pre-calculating timing advance values and distributing them to user devices. This preliminary coordination ensures that all signals will arrive at the satellite within a predictable narrow time window, allowing the satellite to configure its receiver to search only within this constrained time period. This eliminates the need for continuous or wide-window signal capture, significantly reducing processing power consumption while maintaining capture completeness.
Solution Approach 2:
The patent segments the signal reception process into discrete time slots within a narrow time window. The satellite searches for signals in these segmented time slots rather than continuously over a long period. This segmentation approach maintains reliable signal capture for all user devices while dramatically reducing the total processing time and power consumption required.
Data Source
AI summary
A communications system may include a satellite and user equipment (UE) devices. When the UE devices have uplink (UL) packets to transmit, each UE device may randomly select a time slot within a finite time window associated with a time reference of the satellite. The UE device may identify a path length between itself and the satellite and may generate a timing advance based on the path length, the time reference, and the time slot. The satellite may begin to receive the UL packets within the time window and may search received signals over the time window to identify the UL packets. The satellite may recover data payloads from the identified UL packets and may pass the recovered data payloads up a protocol stack. By limiting the search to the time window, the satellite may correctly distinguish the UL packets while using a minimal amount of processing resources.