Wireless Modem LLR Buffer Scaling for Packet-Dependent Decoding
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Solution Overview
Problem
Existing communication systems face challenges in managing buffer memory space for Log-Likelihood Ratio (LLR) values, leading to increased costs due to the need for larger memory capacities, which can be exacerbated by factors like packet size, encoder code rate, and modulation order.
Innovation Solution
Adjusting LLR bit width in the receiver as a function of packet size and encoder code rate, while selecting appropriate demodulators to minimize memory requirements without compromising system performance, and adjusting encoder code rates based on receiver buffer capacity to prevent memory overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If LLR bit width is increased to improve decoding accuracy, then system performance is improved, but LLR buffer memory requirements increase
Solution Approach 1:
The patent implements dynamic adjustment of LLR bit width based on packet size and encoder code rate. The receiver determines the appropriate LLR bit width by receiving packet size information from the transmitter and selecting from multiple predefined bit width values (e.g., 2, 3, 4, 5, 6 bits). This dynamic adaptation allows the system to use smaller bit widths for packets with lower performance requirements, reducing memory usage, while maintaining sufficient bit width for packets requiring higher precision.
Solution Approach 2:
The patent changes the parameter of LLR bit width based on transmission conditions. By receiving encoder code rate information and packet size from the transmitter, the receiver adjusts the LLR bit width parameter to match the specific transmission scenario. This parameter adaptation resolves the contradiction by using minimal necessary precision for each case rather than uniformly high precision.
2Adaptability or versatility
If LLR buffer memory capacity is increased to handle larger packet sizes, then system adaptability is improved, but manufacturing cost increases
Solution Approach 1:
The system dynamically adjusts LLR bit width based on packet size information received from the transmitter. For larger packets, the system can allocate appropriate bit width resources without requiring the entire buffer to be sized for maximum packet scenarios. This dynamic resource allocation enables the system to handle variable packet sizes efficiently with a smaller, more cost-effective buffer.
Solution Approach 2:
The patent changes the LLR bit width parameter according to packet size and encoder code rate. By receiving transmission parameter information and adapting the bit width accordingly, the system achieves high adaptability to different packet sizes without requiring excessive buffer capacity, thereby reducing manufacturing costs.
3Reliability
If fixed high LLR bit width is used to ensure consistent performance, then reliability is improved, but memory usage increases
Solution Approach 1:
The patent implements parameter adaptation by changing LLR bit width based on received transmission parameters (packet size, encoder code rate). This ensures that the system maintains appropriate performance levels for each specific transmission scenario while avoiding the waste of using uniformly high bit width for all cases. The reliability is maintained through adaptive parameter selection rather than fixed high-parameter configuration.
Data Source
AI summary
A system involves a transmitting device (for example, a first wireless communication device) and a receiving device (for example, a second wireless communication device). In the receiving device, LLR (Log-Likelihood Ratio) values are stored into an LLR buffer. LLR bit width is adjusted as a function of packet size of an incoming transmission to reduce the LLR buffer size required and/or to prevent LLR buffer capacity from being exceeded. The receiver may use a higher performance demodulator in order to maintain performance despite smaller LLR bit width. In the transmitting device, encoder code rate is adjusted as a function of receiver LLR buffer capacity and packet size of the outgoing transmission such that receiver LLR buffer capacity is not exceeded. Any combination of receiver LLR bit width adjustment, demodulator selection, and encoder code rate adjustment can be practiced to reduce LLR buffer size required while maintaining performance.