PTT State Detection via Nibbler Protocol in Bluetooth Stack
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Solution Overview
Problem
Existing communication systems experience high latency when transmitting push-to-talk (PTT) states from peripheral devices to communication devices via short-range wireless links, such as Bluetooth, which can result in truncated voice messages due to delays in activating the PTT feature, particularly important for public safety applications where low latency is critical.
Innovation Solution
Implementing a novel 'nibbler' protocol that encodes PTT states into each data message sent over a wireless serial communication channel, allowing the communication device to determine the PTT state at lower layers of the protocol stack, bypassing upper layer processing and reducing latency by creating an autonomous data path for priority signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PTT state is transmitted through the upper layers of the protocol stack in known systems, then the processing is comprehensive and reliable, but the latency increases to 70-400 ms
Solution Approach 1:
The patent segments the protocol stack processing by creating a dedicated autonomous data path that bypasses the upper layers (application layer, transport layer, network layer) and delivers PTT state directly to the lower layers (data link layer, physical layer). This segmentation allows critical PTT signaling to be separated from general data processing, achieving low latency (35 ms) while maintaining reliability through the specialized fast path.
Solution Approach 2:
The patent introduces an intermediary mechanism - the autonomous data path with pattern detector - that mediates between the peripheral device and the radio core. This intermediary captures PTT state messages at the data link layer, detects patterns to determine PTT state, and directly signals the radio core without requiring upper layer processing, thus resolving the contradiction between comprehensive processing and fast delivery.
2Adaptability or versatility
If the peripheral device uses a Virtual Machine or complex Bluetooth chipset, then the functionality is enhanced, but the overhead at higher layers increases latency to 100-400 ms
Solution Approach 1:
The patent extracts the PTT state detection function from the upper layer processing (including VM and Bluetooth chipset overhead) and places it at the data link layer where pattern detectors can identify PTT state messages directly. This extraction removes the latency-causing overhead from the critical PTT signaling path while preserving the enhanced functionality provided by the VM and complex chipset for other purposes.
3Adaptability or versatility
If the radio side wireless adapter manages multiple Bluetooth profiles for multiple peripherals, then the adaptability is improved, but the processor load increases and adds to the latency
Solution Approach 1:
The patent segments the message handling by implementing pattern detectors at the data link layer that can identify and extract PTT state messages from multiple peripherals simultaneously. This segmentation allows the system to maintain multi-peripheral support through the autonomous data path while avoiding the need for high-level software to process each message individually, thus reducing processor load and latency.
Data Source
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AI summary
Apparatus, which has a multilayer protocol stack for processing incoming messages, determines PTT state from messages received from a peripheral over a wireless serial communication channel. The apparatus: receives (902), from the peripheral, a sequence of messages comprising a plurality of data messages (e.g., RFCOMM messages), wherein each of the data messages provides an indication of a PTT state for the apparatus, and wherein the sequence of data messages is received over a short range wireless data path for exchanging priority data that comprises a wireless serial communication channel and that is different from a short range wireless data path for exchanging non-priority data. A pattern detector in the apparatus performs (904) a pattern matching process, within the first two layers of the multilayer protocol stack, to determine the PTT state indicated by each of the data messages and sets (906) the apparatus to have the determined PTT states.