Random Access Preamble Repetition for MTC Coverage
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Solution Overview
Problem
In wireless communication systems, particularly in extreme coverage scenarios, Machine Type Communication (MTC) devices experience significant penetration losses due to their environment, leading to unsuccessful random access procedures and interruptions in the random access process, as they do not finish repetitions of the random access preamble transmission due to premature interruption.
Innovation Solution
The method involves configuring multiple random access response windows for MTC devices in enhanced coverage mode, allowing them to transmit and monitor random access preambles across a longer duration, ensuring successful reception of random access responses by extending the monitoring period beyond the conventional single response window, thereby preventing premature interruption of the random access procedure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MTC devices use conventional single random access response window, then the random access procedure completes quickly, but the devices in extreme coverage scenario cannot receive random access response due to penetration losses and premature interruption
Solution Approach 1:
The patent divides the single random access response window into multiple random access response windows (first RA response window, second RA response window, etc.). Each window corresponds to different repetition groups of random access preambles. This segmentation allows MTC devices in extreme coverage scenarios to monitor for responses over an extended period, increasing the probability of successful reception despite penetration losses, while maintaining structured time management for the random access procedure.
2Reliability
If MTC devices transmit random access preamble repetitions in extreme coverage scenario, then coverage is improved, but the devices experience premature interruption and cannot finish transmissions
Solution Approach 1:
The patent configures multiple random access response windows in advance before the MTC device initiates the random access procedure. The device knows beforehand that it will monitor for responses across multiple windows corresponding to different repetition groups. This preliminary configuration allows the device to persist with transmissions and monitoring without premature interruption, as it understands that the response may arrive in any of the pre-configured windows, thereby completing the full transmission duration needed for extreme coverage scenarios.
3Reliability
If MTC devices extend monitoring period across multiple response windows, then successful reception probability increases, but the complexity of random access procedure increases
Solution Approach 1:
The patent implements a dynamic random access procedure where MTC devices monitor multiple random access response windows in sequence. The device can dynamically stop monitoring after successfully receiving a random access response in any of the windows, or continue to subsequent windows if no response is received. This dynamic approach increases reception reliability by extending the monitoring period while managing complexity through adaptive behavior - the procedure becomes more complex only when necessary for extreme coverage scenarios, not for all devices under all conditions.
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AI summary
A method of handling random access for a user equipment of a wireless communication system includes transmitting a plurality of repetitions of a random access preamble to a network of the wireless communication system; and monitoring a physical downlink control channel (PDCCH) in a plurality of random access response windows for receiving a random access response identified by a random access radio network temporary identifier (RA-RNTI)from the network, wherein each of the plurality of random access response windows is corresponding to one of the plurality of repetitions of the random access preamble.