ACK-less HARQ FEC Spanning Multiple TTIs
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Solution Overview
Problem
Current forward error correction (FEC) techniques in wireless communications require frequent acknowledgment (ACK) and negative acknowledgment (NACK) messages for error correction, leading to increased latency and resource usage due to the need for round-trip confirmations and retransmissions.
Innovation Solution
The implementation of ACK-less Hybrid ARQ (HARQ) using FEC that spans multiple transmission time intervals (TTIs) and incorporates fountain codes, allowing for soft decoding and reduced parity bit quantization, enabling efficient error correction without frequent ACK/NACK transmissions, thereby reducing latency and resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequent ACK/NACK messages are used for error correction, then reliability of data transmission is improved, but latency and resource usage increase
Solution Approach 1:
The patent extracts the acknowledgment feedback mechanism from the traditional HARQ process, implementing an ACK-less system where the receiver does not send frequent ACK/NACK messages. Instead, the transmitter uses FEC-encoded messages with span across multiple TTIs to achieve error correction without the latency overhead of round-trip confirmations
Solution Approach 2:
The patent applies preliminary error correction encoding by spanning FEC across multiple TTIs before transmission. This allows the receiver to perform soft decoding and error correction proactively without waiting for ACK/NACK feedback, reducing the latency caused by waiting for round-trip confirmations
2Reliability
If frequent ACK/NACK messages are used for error correction, then reliability of data transmission is improved, but resource usage increases
Solution Approach 1:
The patent removes the frequent ACK/NACK feedback messages from the communication resource pool. By implementing FEC spanning across multiple TTIs without requiring frequent acknowledgments, the system conserves uplink communication resources that would otherwise be consumed by ACK/NACK transmissions
Solution Approach 2:
The system implements self-service error correction through FEC encoding that spans multiple TTIs. The receiver can independently perform soft decoding and error correction using the redundant information embedded in the spanned FEC codes, without requiring external acknowledgment messages from the transmitter
3Productivity
If FEC spans multiple TTIs with soft decoding, then throughput and latency are improved, but complexity of decoding increases
Solution Approach 1:
The patent changes the decoding parameter from hard decision to soft decoding, which processes reliability information continuously. This allows the receiver to make more informed decoding decisions by considering the confidence level of each received bit, improving throughput while managing complexity through efficient soft decoding algorithms
Data Source
AI summary
A method includes receiving, by a first device from a second device, a plurality of encoded messages on a plurality of transmission time intervals (TTIs), where the plurality of encoded messages are forward error correction (FEC) encoded, and where the FEC spans the plurality of encoded messages and decoding the plurality of encoded messages using FEC. The method also includes determining a plurality of decoding status messages in accordance with decoding the plurality of encoded messages and transmitting, by the first device to the second device, the plurality of decoding status messages less often than once every TTI.