Base Station Paging Retransmission for Extended DRX Reliability
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Solution Overview
Problem
In mobile communication systems, radio terminals using extended DRX cycles face delays in receiving paging messages during cell reselection procedures due to differing downlink control channel transmission timings across cells, leading to potential long-term missed opportunities for message receipt.
Innovation Solution
Implementing a common timing for downlink control channel monitoring across cells within a tracking area, where each base station transmits the channel simultaneously, and providing radio terminals with common timing information to ensure timely message reception, even during extended DRX operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If extended DRX cycle is used to reduce power consumption, then power consumption is reduced, but paging message reception reliability deteriorates due to longer intervals between monitoring opportunities
Solution Approach 1:
The base station performs preliminary actions by transmitting paging messages multiple times in advance at different time points. When using extended DRX cycles, the base station sends the first paging message at the terminal's monitoring timing, and if not acknowledged, transmits a second paging message at a different timing. This preliminary repeated transmission ensures that the message is delivered even if the terminal misses the first transmission due to extended monitoring intervals.
2Adaptability or versatility
If cell reselection procedure is performed during extended DRX operation, then mobility is enabled, but paging message reception timing is delayed due to different downlink control channel transmission timings across cells
Solution Approach 1:
The invention introduces a timing relationship parameter as an intermediary to coordinate between different cells and the terminal's extended DRX cycle. The base station determines the timing of the second paging message transmission based on this parameter, which links the downlink control channel transmission timing of different cells. This intermediary parameter ensures that regardless of which cell the terminal reselects, the paging message can be received at the appropriate extended DRX monitoring timing.
3Ease of manufacture
If downlink control channel transmission timing is different for each cell, then cell-specific optimization is achieved, but paging message delivery reliability deteriorates during cell reselection
Solution Approach 1:
The invention changes the timing parameter of the second paging message transmission based on the terminal's extended DRX cycle and the timing relationship between cells. Instead of using fixed cell-specific timing, the base station adjusts the transmission timing parameter to align with the terminal's extended monitoring opportunities. This parameter change ensures that paging messages are delivered reliably during cell reselection while maintaining cell-specific configuration flexibility for other purposes.
Data Source
AI summary
A base station according to one embodiment comprises a transmitter configured to transmit a downlink control channel for a radio terminal to receive, in an idle mode, a paging message; and a controller configured to retransmit a paging message addressed to the radio terminal, if an extended DRX using a second DRX cycle longer than a first DRX cycle is configured to the radio terminal.