TDMA Slot Structure Time-Shifting for Uplink Collision Prevention
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Solution Overview
Problem
In wireless communication systems using a fixed TDMA structure, uplink transmission bursts from mobile devices with varying propagation delays can collide at the network side due to a fixed guard period, leading to data loss, especially in larger cells where propagation delays become excessive.
Innovation Solution
The solution involves time-shifting transmission times in the fixed slot structure based on a minimum path delay value, allowing for dynamic adjustment of uplink bursts to prevent collisions, without requiring real-time measurements or additional signaling, thereby extending the cell size while maintaining collision-free data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed guard period is used in the fixed TDMA structure, then collision prevention is simplified and device complexity is reduced, but transmission bursts collide at the network side when mobile apparatuses have different propagation delays, leading to data loss
Solution Approach 1:
The patent applies local quality by introducing a cell-specific minimum path delay parameter that adjusts the slot structure locally for each cell based on its maximum propagation delay characteristics. This allows each cell to have optimized slot timing tailored to its specific geometry and coverage area, preventing collisions at the network side while maintaining the overall fixed TDMA structure.
Solution Approach 2:
The patent changes the timing parameter of the slot structure by shifting slot start times based on the minimum path delay value. This parameter adjustment compensates for propagation delays in larger cells, ensuring that transmission bursts from remote mobile apparatuses arrive within their allocated slots without colliding with bursts from other slots.
2Area of stationary object
If the cell size is increased to provide larger coverage area, then network coverage is improved, but propagation delays become excessive causing transmission bursts to collide at the network side
Solution Approach 1:
The patent enables larger cell areas by applying local timing adjustments based on the minimum path delay specific to each cell. This allows the network to support extended coverage areas while maintaining reliable data transmission by compensating for increased propagation delays through slot structure adaptation.
Solution Approach 2:
The patent introduces dynamic timing adjustment capability where the slot structure adapts to cell size through the minimum path delay parameter. This allows the system to dynamically accommodate varying cell radii and propagation conditions while maintaining collision-free transmission.
3Reliability
If an adaptive TDMA structure is used to adjust transmission timing based on propagation delay, then collision prevention is improved, but real-time measurements and additional signaling are required increasing device complexity
Solution Approach 1:
The patent applies preliminary action by pre-calculating and configuring the minimum path delay parameter for each cell based on expected maximum propagation delays. This allows the slot structure to be optimized in advance for different cell sizes without requiring real-time measurements or dynamic adjustments during operation, thereby maintaining reliability while reducing complexity.
Solution Approach 2:
The patent uses parameter changes to adjust the slot timing based on the minimum path delay value, achieving collision prevention through static timing offsets rather than dynamic adaptive adjustments. This approach maintains reliability while avoiding the complexity of real-time measurement and signaling mechanisms.
Data Source
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AI summary
In the time division multiple access technique with a fixed slot structure on an air interface, the fixed slot structure comprising a guard period between two uplink bursts in two consecutive slots, at least one cell is provided with a minimum path delay value or information with which the minimum path delay value may be determined, and in the at least one cell transmissions times defined in the fixed slot structure are shifted according to the minimum path delay.