Radio Base Station Back-off Indicator for Random Access Collision Control
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Solution Overview
Problem
In LTE mobile communication systems, simultaneous transmission of random access preambles by multiple mobile stations can lead to collisions, lowering the success probability of the random access procedure.
Innovation Solution
A radio base station and mobile communication method that includes a Back-off Indicator transmission unit to notify a Back-off value when a predetermined condition is met, adjusting the timing of random access preamble transmission to prevent collisions, by increasing or decreasing the Back-off value based on the usage situation, such as the number of preambles received within specific thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple mobile stations transmit random access preambles simultaneously, then the random access procedure can be initiated quickly, but collision probability increases and success probability decreases
Solution Approach 1:
The base station implements periodic monitoring of random access preamble usage and periodically transmits backoff indicators to mobile stations. This periodic control mechanism allows the system to maintain quick access initiation while periodically adjusting transmission timings to avoid collisions, thus resolving the contradiction between speed and success probability
Solution Approach 2:
The base station monitors the usage situation of random access preambles and provides feedback to mobile stations through backoff indicators. This feedback mechanism enables mobile stations to adjust their transmission timings based on current channel conditions, reducing collisions while maintaining efficient access initiation
2Ease of operation
If mobile stations transmit random access preambles without timing adjustment, then transmission is simple and quick, but collisions occur when multiple stations access the same cell
Solution Approach 1:
The base station acts as an intermediary that monitors preamble usage and introduces backoff indicators as a mediating control signal. These indicators guide mobile stations to adjust their transmission timings, preventing collisions while maintaining the simplicity of the overall transmission process for mobile stations
3Reliability
If backoff indicator is transmitted frequently to reduce collisions, then random access success probability improves, but signaling overhead and system complexity increase
Solution Approach 1:
The base station dynamically changes the backoff parameter values in backoff indicators based on monitored preamble usage conditions. By adjusting these parameters adaptively rather than transmitting frequent control signals, the system improves success probability while minimizing signaling overhead and system complexity
Data Source
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AI summary
A radio base station (eNB) according to the present invention includes: a Back-off Indicator transmission unit (14) configured to transmit a Back-off Indicator notifying a Back-off value when a usage situation of an RA preamble satisfies a predetermined condition, in a random access procedure, wherein the Back-off value is a value relating to a timing of transmitting the RA preamble in a mobile station (UE).