PRACH Preamble Allocation for Satellite Random Access Contention
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Solution Overview
Problem
Satellite communication systems face inefficiencies due to long propagation delays and increased risk of random access preamble collisions, leading to unreliable initial access procedures and contention resolution issues in wireless networks.
Innovation Solution
A method is introduced to reduce the number of physical random access channel preambles and dynamically adjust uplink grant allocations based on communication traffic levels, ensuring timely and efficient random access by using a reduced set of preambles and optimizing resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of physical random access channel preambles is reduced, then the risk of random collisions between different UEs decreases, but the ability to handle high communication traffic volumes is worsened
Solution Approach 1:
The patent applies dynamics by making the number of available preambles configurable and adaptable rather than fixed. The base station can dynamically adjust the number of preambles assigned to each UE based on real-time communication traffic conditions, allowing the system to optimize between collision avoidance and traffic handling capacity as needed
Solution Approach 2:
The patent applies local quality by assigning different numbers of preambles to different UEs based on their individual traffic patterns and collision risks. Instead of uniform treatment, each UE receives a customized preamble allocation that matches their specific communication needs and environmental conditions
2Quantity of substance
If the number of available preambles is reduced to four, then the random access response message size is minimized, but the probability of collision increases when multiple UEs transmit simultaneously
Solution Approach 1:
The patent applies partial action by assigning fewer preambles than the maximum possible (e.g., four preambles instead of six4), which minimizes message size while accepting that some collisions may occur. The system compensates for this by using other mechanisms like contention resolution procedures and retransmission strategies
3Reliability
If timing advance is increased to compensate for long propagation delay, then the random access procedure becomes more reliable in satellite networks, but the overall access time is increased
Solution Approach 1:
The patent applies preliminary action by having the base station configure and communicate timing advance values to UEs before the actual random access transmission occurs. This allows UEs to prepare their transmission timing in advance, reducing the overall access time while maintaining reliability through proper timing compensation for propagation delay
Data Source
AI summary
A method and system for providing a communications channel between a user equipment (UE) and a base station, the method includes base station determining a level of communications traffic. the base station transmitting a random access response (RAR) message including a plurality of different physical random access channel (PRACH) preamble signatures, wherein if the determined level of communications traffic is below a threshold then the RAR message includes the same uplink grant allocation for each of the plurality of different PRACH preamble signatures, and if the determined level of communications traffic is above the threshold then the RAR message includes different uplink grant allocations for each of the plurality of different PRACH preamble signatures.