LDPC Coding Rate Adaptation for 5G HARQ Buffer Constraints
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Solution Overview
Problem
The 5G communication system requires adaptive modulation and coding techniques to efficiently manage power consumption and buffer size in LDPC code-based systems, particularly for varying data transfer rates and channel conditions, as existing methods do not effectively adjust coding rates in response to changing conditions.
Innovation Solution
A method and apparatus for dynamically changing the mother coding rate in an IR-HARQ scheme using LDPC codes, where the reception terminal requests and adjusts the coding rate based on battery and HARQ buffer states, and the transmission terminal determines and transmits the new coding rate, allowing for efficient power management and buffer optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a decoder corresponding to the lowest coding rate is implemented to support low data transfer rates, then the system can support both high and low data transfer rates, but the size of the required HARQ buffer is increased
Solution Approach 1:
The patent applies dynamics by making the mother coding rate variable rather than fixed. The transmission terminal and reception terminal dynamically adjust the mother coding rate based on current channel conditions, battery state, and HARQ buffer status. This allows the system to adapt between high and low data transfer rates without requiring a decoder designed for the lowest coding rate, thereby reducing the HARQ buffer size while maintaining versatility.
Solution Approach 2:
The patent changes the parameter of mother coding rate from a static value to a dynamically adjustable parameter. By establishing a mapping relationship between different mother coding rates and transmission parameters, the system can switch between different coding rates (e.g., 1/3, 2/3, 3/4) based on current conditions, eliminating the need to always use the lowest coding rate and its associated large buffer requirements.
2Use of energy by moving object
If the entire decoding is performed by using a low coding rate to reduce consumed power, then power consumption is reduced, but the size of the required HARQ buffer is increased
Solution Approach 1:
The system dynamically adjusts the mother coding rate based on real-time conditions including battery state and channel quality. When channel conditions are good and battery level is sufficient, higher coding rates can be used, reducing the need for extensive retransmission decoding and thereby reducing power consumption without requiring large HARQ buffers. The dynamic adaptation prevents the system from always being in a low coding rate state that would require large buffers.
3Productivity
If various transmission techniques are used to obtain performance gain by adaptively changing modulation parameter and coding rate, then system efficiency is improved, but the complexity of the system is increased
Solution Approach 1:
The patent implements feedback mechanisms where the reception terminal sends state information (battery state, channel quality) back to the transmission terminal. Based on this feedback, the transmission terminal determines the appropriate mother coding rate and transmits control information accordingly. This feedback-driven approach enables adaptive transmission that improves system efficiency while keeping the complexity manageable through structured information exchange and predetermined mapping relationships.
Solution Approach 2:
The patent creates a universal control mechanism that handles multiple functions through a unified approach. The same control information structure and mapping methodology work across different coding rates (1/3, 2/3, 3/4) and different terminal states, eliminating the need for separate complex control logic for each scenario. This multi-functional design improves efficiency while controlling complexity.
Data Source
AI summary
Fifth Generation (5G) or pre-5G communication system for supporting a data transfer rate higher than that of a fourth Generation (4G) communication system, such as Long Term Evolution (LTE), and subsequent systems. The present disclosure provides a method for transmitting a signal by a transmission terminal in a communication system using a Low Density Parity Check (LDPC) code. The method include receiving a change request for changing a coding rate of the LDPC code, from a reception terminal; determining a first coding rate based on the change request; and transmitting information on the first coding rate in respond to the change request, to a reception terminal, wherein the change request for changing the coding rate comprises at least one of information indicating a coding rate determined by the reception terminal, or information indicating a state of the reception terminal.