Variable Correlation Interval for Bluetooth Slave Synchronization
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Solution Overview
Problem
Bluetooth piconet transceivers face synchronization loss due to timing mismatches exceeding the ±10 μs uncertainty window, leading to connection loss during inquiries or pages, especially when environmental disturbances occur, and current solutions like increasing the uncertainty window or using Hold mode are either not compliant with specifications or inefficient in power usage.
Innovation Solution
A low power radio frequency transceiver dynamically adjusts its synchronization window based on the time since the last packet detection, allowing for variable correlation intervals to maintain synchronization without entering Hold mode and minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the master performs Inquiry or Page operations, then the master can discover new devices or re-establish connections, but all slaves lose synchronization and connection during this time
Solution Approach 1:
The patent applies dynamics by making the correlation interval variable rather than fixed. The slave dynamically adjusts its synchronization window based on the time elapsed since the last successful packet reception. When the master performs Inquiry or Page operations causing interruption, the slave extends its correlation interval to accommodate the timing disruption, thereby maintaining synchronization without requiring Hold mode.
Solution Approach 2:
The patent changes the parameter of correlation interval duration from a fixed value to a variable value that adapts to operational conditions. By modifying this timing parameter based on the elapsed time since last successful communication, the slave can tolerate the temporary desynchronization caused by master's Inquiry/Page operations while maintaining connection reliability.
2Use of energy by moving object
If the slave uses a fixed uncertainty window for packet reception, then power consumption is minimized, but synchronization is lost when timing mismatch exceeds the window
Solution Approach 1:
The patent transitions from a static fixed uncertainty window to a dynamic variable correlation interval. The slave monitors the time elapsed since the last successful packet detection and adjusts the correlation interval accordingly. This dynamic adjustment allows the slave to maintain synchronization reliability during disturbances without permanently increasing power consumption, as the extended interval is temporary and condition-dependent.
Solution Approach 2:
The patent implements feedback by having the slave continuously monitor its synchronization status and adjust the correlation interval based on the time elapsed since the last successful packet reception. This feedback mechanism allows the slave to detect when timing mismatch is approaching the threshold and proactively extend the correlation interval to prevent synchronization loss, while returning to the shorter interval once synchronization is restored.
3Reliability
If the slave extends the uncertainty window to prevent synchronization loss, then connection reliability improves, but power consumption increases permanently
Solution Approach 1:
The patent ensures that the correlation interval extension is temporary and conditional rather than permanent. The slave only extends the correlation interval when necessary (when timing mismatch exceeds the fixed window or during master's Inquiry/Page operations) and returns to the original shorter interval once synchronization is restored. This dynamic behavior maintains connection reliability during disturbances while avoiding permanent power consumption increase.
Solution Approach 2:
The patent employs periodic monitoring of the time elapsed since the last successful packet detection. The slave periodically checks whether the elapsed time exceeds a threshold and adjusts the correlation interval accordingly. This periodic action ensures that the extended correlation interval is activated only when needed and deactivated when not required, preventing permanent power consumption increase while maintaining reliability during critical periods.
Data Source
AI summary
A slave low power radio frequency transceiver participates in a network controlled by a master low power radio frequency transceiver and synchronises its timing to the network timing by receiving radio packets transmitted from the controlling low power radio frequency transceiver. The slave transceiver comprises timing means; detection means operable over an interval of time for detecting a predetermined portion of a received radio packet; and adjusting means for adjusting the timing means in response to the detection of a predetermined portion of a received radio packet. The slave low power radio frequency transceiver is arranged to controllably vary the duration of the interval of time.