Elevation-Aware Uplink Timing for Satellite Signal Separation
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Solution Overview
Problem
The accuracy in separating wireless signals from multiple terminal stations at different directions is insufficient due to the limitations in the existing CSMA/CA scheme, leading to potential signal collisions and reduced separation accuracy at reception array antennas of low earth orbit satellites.
Innovation Solution
A wireless communication apparatus and method that determines an earlier transmission timing based on the elevation angle of the relay apparatus relative to the terminal station, adjusting the backoff counter value to optimize signal separation by prioritizing transmissions from stations with larger elevation angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CSMA/CA scheme with uniform backoff counter subtraction is used, then the transmission timings of terminal stations are uniformly distributed, but the accuracy in separating wireless signals from multiple terminal stations at different directions is insufficient
Solution Approach 1:
The patent applies local quality by making the backoff counter subtraction value location-dependent. Specifically, terminal stations at different locations (with different elevation angles relative to the relay apparatus) use different subtraction values. Terminal stations with larger elevation angles use larger subtraction values, while those with smaller elevation angles use smaller subtraction values. This localized differentiation improves signal separation accuracy at the reception array antennas without requiring complex centralized control.
2Productivity
If terminal uplink signals are transmitted at the same timing, then the transmission process is simple, but the terminal uplink signals may collide with each other
Solution Approach 1:
The patent implements periodic action through the backoff mechanism where terminal stations transmit signals at different timing intervals. By subtracting different values from their backoff counters, terminal stations distribute their transmission timings periodically across different time slots. This maintains transmission efficiency while significantly reducing signal collision probability, as stations with different elevation angles transmit at different times rather than simultaneously.
3Measurement precision
If the subtraction value is uniformly set to 1 for all terminal stations, then the implementation is simple, but the separation accuracy of signals from terminal stations close to each other varies depending on their directions
Solution Approach 1:
The patent applies parameter changes by modifying the backoff counter subtraction value based on the elevation angle parameter. Instead of using a fixed uniform value of 1, the subtraction value is changed according to the terminal station's location relative to the relay apparatus. Terminal stations with larger elevation angles use larger subtraction values, while those with smaller elevation angles use smaller subtraction values. This parameter adaptation improves signal separation accuracy without significantly increasing system complexity.
Data Source
AI summary
A wireless communication apparatus includes: a transmission control unit that determines an earlier transmission timing as an elevation angle of a relay apparatus when viewed from the own wireless communication apparatus is larger; and a transmission unit that transmits a wireless signal to the relay apparatus at the transmission timing. The wireless communication apparatus may further include a reception unit that acquires an upper limit value. The transmission control unit may derive a subtraction value, which is a variable value to be used for subtraction, as a larger value as the elevation angle is larger, may subtract the subtraction value from a backoff counter value which is derived based on the upper limit value and is equal to or larger than 0, and may determine, as the transmission timing, a timing at which the backoff counter value becomes equal to or smaller than 0.