BLE Packet Error Correction Using Softbit Metrics and CRC
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Solution Overview
Problem
Wireless communication systems face challenges with bit errors, particularly in Bluetooth Low Energy (BLE) networks, where increasing packet size and bit error rate lead to a significant increase in retransmissions, impacting delay and power consumption, and existing methods to improve receiver sensitivity come with negative trade-offs like increased complexity and power consumption.
Innovation Solution
Implementing a softbit quality metric to identify likely bit error positions and correct bits in corrupted packets by flipping hypothesized error positions, using techniques such as flipping single or consecutive bits based on softbit metrics and CRC checks to reduce the need for retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If retransmissions are used to combat bit errors, then reliability is improved, but delay and power consumption increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing syndrome tables for all possible single-bit and double-bit error patterns before communication occurs. When errors are detected via CRC, the system can immediately look up the error pattern in the pre-computed syndrome table and correct the bits without requiring retransmission, thus maintaining reliability while reducing delay
Solution Approach 2:
The patent creates a copy of the received packet and uses syndrome calculation to identify error patterns. By comparing the received packet with corrected versions generated from syndrome tables, the system can reconstruct the error-free packet without needing the original transmission, eliminating the need for retransmission and reducing delay
2Reliability
If retransmissions are used to combat bit errors, then reliability is improved, but power consumption increases
Solution Approach 1:
The syndrome tables are pre-computed and stored in memory before communication begins. This preliminary preparation allows the receiver to correct errors using simple table lookups and bit flipping operations, avoiding the need for power-intensive retransmission cycles and reducing overall power consumption while maintaining reliability
Solution Approach 2:
By creating corrected packet copies using syndrome-based error identification and applying softbit metrics to guide corrections, the system can reconstruct error-free packets locally without requiring additional transmissions, thereby reducing the power consumption associated with multiple transmission cycles
3Reliability
If receiver sensitivity is improved by reducing noise figure, then bit error rate is reduced, but current consumption increases
Solution Approach 1:
The patent changes the approach from improving physical layer parameters (noise figure, SNR) to changing the processing layer parameters (syndrome calculation, softbit metrics). By using softbit quality metrics to identify likely error positions and applying intelligent error correction algorithms, the system achieves lower bit error rates without increasing analog front-end current consumption
4Reliability
If receiver sensitivity is improved by designing demodulator for lowest SNR, then bit error rate is reduced, but design complexity increases
Solution Approach 1:
The patent shifts the complexity from the demodulator design to the error correction processing stage. By implementing syndrome calculation, softbit metric computation, and table lookup-based correction, the system achieves robust error correction without requiring complex demodulator designs optimized for lowest SNR, thereby reducing design complexity while maintaining reliability
Data Source
AI summary
Disclosed are methods and systems for a Bluetooth Low Energy (BLE) receiver to reduce the number of retransmission of packets needed to receive an error free packet. A softbit metric of a demodulator may be used to identify likely bit error positions of a corrupted packet and to correct bits of the corrupted packet corresponding to the identified bit error positions. When a demodulated packet fails the CRC, a receiver may identify one or more hypothesized bit error positions for the demodulated bits of the packet based on the softbit metric. The receiver may flip one or more of the demodulated bits corresponding to the hypothesized bit error positions. The receiver may determine if the packet after flipping the demodulated bits passes the CRC. If the CRC passes, the hypothesized bit error positions identifies the bit error positions of the corrupted packet and the receiver has corrected the bit errors.