Half-Duplex Uplink Timing for Large Timing Advance Conflicts
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Solution Overview
Problem
Low-cost terminal devices in satellite communication face conflicts between uplink and downlink transmissions due to large timing advances, necessitating simultaneous receiving and sending in a half-duplex mode with significant latency.
Innovation Solution
An uplink timing method that determines unavailable time units for transmission based on scheduling offsets and extension intervals, allowing devices to skip these units to avoid simultaneous receiving and sending, thereby reducing conflicts and improving uplink utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a low-cost terminal device uses half-duplex mode to perform uplink scheduling and downlink receiving in satellite communication, then the device can operate with reduced complexity and cost, but the large timing advance (tens to hundreds of slots) causes conflict between uplink transmission and downlink transmission requiring simultaneous sending and receiving
Solution Approach 1:
The patent segments the time units into two distinct sets: a first set for downlink receiving and a second set for uplink transmission. By determining the second set based on the extension interval and the first set, the patent ensures that uplink transmission time units do not overlap with downlink receiving time units, thereby avoiding half-duplex conflicts while maintaining clear temporal separation between receiving and sending operations
Solution Approach 2:
The patent performs preliminary determination of the second set of time units for uplink transmission before actual transmission occurs. By calculating the extension interval and identifying unavailable time units in advance, the system proactively prevents scheduling conflicts between uplink and downlink, ensuring that the terminal device never needs to simultaneously receive and transmit
2Productivity
If the terminal device determines uplink transmission time units without considering the extension interval, then the scheduling is simpler and faster, but the large timing advance causes overlap between uplink transmission slots and downlink receiving slots
Solution Approach 1:
The patent introduces a dynamic extension interval that adapts to the specific timing advance requirements of satellite communication. Rather than using fixed time unit allocation, the system dynamically determines the second set of time units based on the calculated extension interval, allowing the scheduling to flexibly accommodate the large timing advance while maintaining high utilization of available uplink slots
Solution Approach 2:
The patent implements a skipping mechanism where the terminal device identifies and skips unavailable time units in the second set that would cause half-duplex conflicts. By calculating which time units to skip based on the extension interval and first set, the system efficiently bypasses conflicting slots without requiring complex real-time arbitration, thereby maintaining scheduling speed while avoiding transmission conflicts
Data Source
AI summary
This application provides an uplink timing method. A half-duplex terminal device determines, based on a maximum timing advance of an area in which the terminal device is located and a set of time units used by the terminal device to receive a system message, a set of time units unavailable for uplink transmission, and in a process of calculating a time unit for sending an uplink signal, skips, based on a scheduling offset of the uplink signal, a time unit in the set of time units unavailable for uplink transmission, to avoid a problem that the half-duplex device needs to simultaneously perform receiving and sending in a large transmission latency scenario.