DRX Cycle Alignment for Multicast Latency Reduction
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Solution Overview
Problem
In IoT wireless communication systems, multicast and broadcast transmissions face delays and buffering issues due to varying DRX cycles among wireless terminals and gateways, leading to inefficient data delivery and increased latency.
Innovation Solution
A control entity configures wireless terminals and gateways to align their DRX cycles, creating a common reception period for simultaneous data transmission, reducing the need for buffering and minimizing latency by synchronizing listen intervals and adapting DRX parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If wireless terminals use different DRX cycles to optimize power consumption, then energy efficiency is improved, but multicast and broadcast transmission latency increases due to lack of simultaneous reception
Solution Approach 1:
The system dynamically adjusts DRX cycle parameters (duration, offset, start time) to create overlapping reception windows. By modifying these parameters, the system enables simultaneous reception for multicast/broadcast while allowing terminals to maintain extended sleep periods for power saving.
Solution Approach 2:
The network configures DRX parameters in advance to pre-establish common reception periods. This preliminary configuration ensures that when multicast or broadcast transmissions occur, all targeted terminals are guaranteed to be in reception mode, eliminating latency without requiring real-time coordination.
2Reliability
If multicast traffic is transmitted at lowest transmission rate to improve reception probability, then reliability is improved, but transmission time and latency increase
Solution Approach 1:
The system uses periodic DRX cycles with synchronized reception windows to enable reliable reception at higher transmission rates. By creating periodic opportunities for all terminals to be awake simultaneously, the system can transmit at optimized rates rather than the lowest possible rate, reducing transmission time while maintaining reliability.
3Reliability
If gateways buffer multicast traffic for sleeping terminals, then delivery reliability is improved, but buffering complexity and memory requirements increase
Solution Approach 1:
The system extracts the synchronization function from the gateway buffering operation. Instead of the gateway buffering traffic for sleeping terminals, the DRX synchronization ensures all terminals wake up simultaneously to receive transmissions directly, eliminating the need for gateway buffering infrastructure and reducing complexity.
4Adaptability or versatility
If listen intervals are negotiated individually for each terminal, then adaptability to individual needs is improved, but signaling overhead and configuration complexity increase
Solution Approach 1:
The system merges individual terminal DRX configurations into a coordinated group configuration. By establishing common reception periods that satisfy multiple terminals simultaneously, the system reduces signaling overhead while maintaining adaptability to individual power and latency requirements through parameter optimization.
Data Source
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AI summary
A control entity in a wireless communications system obtains discontinuous reception information for a plurality of wireless terminals and configures one or more of said wireless terminals, based on the obtained discontinuous reception information, to harmonise the awake periods of the plurality of wireless terminals. The control entity determines a common reception period for the plurality of wireless terminals such that a broadcast or multicast transmission during the common reception period is received simultaneously by the wireless terminals.