Dynamic Bundle Size Adaptation in HARQ Retransmissions
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Solution Overview
Problem
In wireless communication networks, especially for Machine Type Communication (MTC) devices, the existing Hybrid Automatic Repeat Request (HARQ) mechanism leads to unnecessary repetitions and resource wastage due to inflexible bundle sizes, causing delays and increased power consumption, particularly in poor radio conditions.
Innovation Solution
The method involves dynamically configuring bundle sizes for initial and retransmission attempts within a HARQ process, using a larger initial bundle size and successively smaller bundle sizes for subsequent retransmissions, based on channel conditions and historical data, to minimize unnecessary repetitions and feedback signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed large bundle size is used for all transmission attempts in HARQ, then coverage is improved in poor radio conditions, but unnecessary repetitions and resource wastage occur when channel conditions are good
Solution Approach 1:
The patent applies dynamics by making the bundle size adaptive rather than fixed. The bundle size is dynamically adjusted based on channel conditions, device category, and transmission history. Good channel conditions trigger smaller bundle sizes to save power, while poor conditions trigger larger bundle sizes to ensure coverage, directly resolving the contradiction between reliability and energy loss.
Solution Approach 2:
The patent changes the parameter of bundle size based on different conditions. Specifically, it modifies bundle size according to channel quality indicators, device capability categories, and transmission attempt history. This parameter adaptation allows the system to optimize between coverage and power consumption by matching bundle size to actual channel requirements rather than using a fixed conservative value.
2Reliability
If a fixed large bundle size is used for all transmission attempts in HARQ, then coverage is improved in poor radio conditions, but control signaling overhead increases due to unnecessary feedback signals
Solution Approach 1:
The patent makes the bundle size dynamic based on channel conditions and transmission context. When channels are good, smaller bundle sizes reduce the number of retransmissions and associated feedback signaling. When channels are poor, larger bundle sizes ensure successful delivery in fewer attempts, reducing overall control overhead. This dynamic adjustment directly addresses the control signaling overhead issue.
Solution Approach 2:
The patent changes bundle size parameters based on measured channel quality and device category. By adapting this parameter to actual conditions rather than using a fixed conservative value, the system reduces unnecessary retransmissions and their associated control feedback, thereby reducing control signaling overhead while maintaining coverage where needed.
3Reliability
If HARQ retransmissions are performed with the same bundle size as initial transmission, then soft combining can be effective, but delays increase due to unnecessary retransmission attempts
Solution Approach 1:
The patent applies dynamics by adjusting bundle size for retransmissions based on whether the initial transmission succeeded. If the initial transmission with a larger bundle succeeded, retransmissions use smaller bundles, reducing delay. If it failed, the system learns from the failure and adjusts subsequent retransmission bundle sizes accordingly. This dynamic adjustment maintains error correction effectiveness while reducing unnecessary retransmission delays.
Solution Approach 2:
The patent changes the bundle size parameter for retransmissions based on transmission history and channel conditions. By reducing bundle size for retransmissions when appropriate, the system maintains the ability to perform soft combining for error correction while significantly reducing the time consumed by unnecessary retransmission attempts, thus resolving the delay issue.
4Reliability
If TTI bundling is applied to all physical channels with fixed repetitions, then coverage is enhanced for MTC devices, but device complexity and scheduling difficulty increase
Solution Approach 1:
The patent applies local quality by differentiating TTI bundling configuration across different device categories, physical channels, and channel conditions. Instead of uniformly applying fixed repetitions to all channels and devices, the system tailors the bundling size locally based on specific device capabilities, channel requirements, and traffic patterns. This reduces overall system complexity while maintaining coverage enhancement where needed.
Solution Approach 2:
The patent makes TTI bundling configuration dynamic rather than fixed. The bundling size adapts based on device category, physical channel type, and measured channel conditions. This dynamic approach reduces scheduling complexity by allowing the network to optimize bundling parameters for different local conditions rather than managing a single complex fixed configuration across all scenarios.
Data Source
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AI summary
Apparatus and Method for handling the configuration of bundle sizes in communications involving the transmission and/or reception of more than one bundle in a transmission and/or reception attempt A method in a wireless network node for handling the configuration of bundle sizes in communications involving the transmission and/or reception of more than one bundle in a transmission and/or reception attempt, comprises the step of initiating the use of a first bundle size for communicating with a wireless device during an initial transmission and/or an initial reception, the first bundle size comprising a first number of repetitions. The method comprises initiating the use of at least a second bundle size for communicating with the wireless device during at least one retransmission and/or subsequent reception associated, respectively, with the initial transmission and/or initial reception, wherein the at least second bundle size comprises a smaller number of repetitions compared to the first bundle size.