Buffer Management for D2D Soft Combining
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Solution Overview
Problem
In Device-to-Device (D2D) communication, the lack of separate resource allocation for soft combining in the Hybrid Automatic Repeat Request (HARQ) procedure poses challenges in managing buffers effectively, particularly in channel conditions where system efficiency is low.
Innovation Solution
A method and wireless device that manage a buffer for soft combining by determining whether to use an instantaneous buffer or a HARQ buffer based on the Radio Resource Control (RRC) connection with a base station and carrier aggregation status, prioritizing the instantaneous buffer in poor channel conditions and the HARQ buffer in better conditions, and storing soft bits in the selected buffer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the HARQ buffer is used for soft combining in D2D communication, then transmission reliability is improved, but system efficiency deteriorates in poor channel conditions due to time delay
Solution Approach 1:
The patent applies dynamics by making the buffer selection adaptive rather than fixed. The wireless device dynamically selects between instantaneous buffer and HARQ buffer based on real-time channel conditions (SNR measurements). In good channel conditions, the instantaneous buffer is used for faster processing; in poor conditions, the HARQ buffer is used for higher reliability, thus optimizing the trade-off between reliability and system efficiency under varying conditions.
Solution Approach 2:
The patent changes the parameter of buffer selection based on channel condition parameters (SNR). By monitoring channel quality and adjusting which buffer type is used accordingly, the system adapts its behavior to maintain optimal performance. This parameter-based adaptation resolves the contradiction by allowing the system to prioritize reliability when needed and efficiency when possible.
2Productivity
If the instantaneous buffer is used for soft combining, then system efficiency is improved, but transmission reliability deteriorates in poor channel conditions
Solution Approach 1:
The system dynamically adjusts buffer selection based on channel conditions. When SNR indicates poor channel quality, the system switches to using the HARQ buffer which provides better reliability through retransmission capabilities. When channel conditions are good, it uses the instantaneous buffer for faster processing, thus dynamically balancing efficiency and reliability.
Solution Approach 2:
The selection parameter (which buffer to use) is changed based on the channel condition parameter (SNR). This parameter change mechanism allows the system to transition between efficiency-oriented and reliability-oriented modes depending on the operational context, resolving the contradiction between these two objectives.
3Productivity
If separate resource allocation for soft combining is implemented in D2D HARQ procedure, then buffer management performance is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by making the existing buffer structures (instantaneous buffer and HARQ buffer) serve multiple purposes. These buffers are not dedicated exclusively to one function but can be selectively used for soft combining in D2D communication based on needs. This multi-functional use improves buffer management performance without requiring entirely new dedicated resources, thus avoiding excessive complexity increase.
Solution Approach 2:
The wireless device autonomously performs buffer selection based on its own channel condition assessments. The device self-determines which buffer to use by evaluating SNR and selecting accordingly, without requiring complex centralized control or additional signaling overhead. This self-service approach improves buffer management while keeping device complexity manageable.
Data Source
AI summary
One embodiment of the present specification provides a method by which a wireless device manages a buffer for performing soft combining. The method can comprise the steps of: decoding data received through device-to-device (D2D) communication; determining whether an error exists in the decoded data; determining whether a radio resource control (RRC) connection with a base station is established or/and a carrier aggregation is configured and activated if the error exists; taking at least one from among an instantaneous buffer to be used when the carrier aggregation is activated and a hybrid automatic repeat request (HARQ) buffer to be used when the RRC connection is established, on the basis of whether the RRC connection with the base station is established and whether the carrier aggregation is activated; and storing, in the taken one or more buffers, a soft bit for performing soft combining.