5G Random Access Backoff Balancing Collisions and Delay
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Solution Overview
Problem
The existing random access procedure in 5G communication systems is inefficient and prone to delays and collisions due to unnecessary backoff in contention-based random access preamble retransmissions, especially when transitioning from contention-free to contention-based resources.
Innovation Solution
An enhanced method for random access backoff is introduced, where a UE elects a random backoff time based on a uniform distribution and periodically checks for suitable synchronization signals to select contention-free resources, thereby reducing delays and collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a UE applies backoff parameter in contention-based random access preamble retransmission, then collision probability is reduced, but access delay increases
Solution Approach 1:
The patent changes the backoff parameter from a fixed value to a dynamically selected value from multiple candidate backoff parameters. The UE selects different backoff parameters based on the type of random access procedure (initial access, handover, beam failure recovery), thereby optimizing the balance between collision reduction and access delay for different scenarios
Solution Approach 2:
The patent introduces dynamic selection of backoff parameters where the UE adapts the backoff value based on the random access type and network conditions. This dynamic approach allows the system to adjust the backoff behavior rather than using a static backoff value, improving both collision handling and access efficiency
2Reliability
If a UE performs random access preamble retransmission with backoff, then retransmission success rate is improved, but procedure completion time increases
Solution Approach 1:
The patent changes the backoff parameter from a single fixed value to multiple candidate values that are selectively applied. By having different backoff parameters for different random access types, the system can achieve higher retransmission success rates while minimizing the impact on procedure completion time for time-critical operations
3Quantity of substance
If a UE uses contention-based random access resources, then resource availability is increased, but access efficiency decreases
Solution Approach 1:
The patent segments the random access resources into different types (contention-free and contention-based) and applies different backoff strategies for each. Contention-free resources are used for specific scenarios like handover and beam failure recovery where immediate access is critical, while contention-based resources are used for general access. This segmentation allows the system to maintain high resource availability while improving access efficiency for time-critical operations
Data Source
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AI summary
A communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for internet of things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology. The present disclosure provides a method and an apparatus for performing a random access by a terminal in a wireless communication system by starting a backoff timer for a random access preamble retransmission, determining whether a criterion to select a contention free random access resource is met during the backoff timer, selecting a random access resource for a transmission of a random access preamble when the criterion is met during the backoff timer, and transmitting, to a base station, the random access preamble in the selected random access resource.