Coordinated Roaming for BLE Peripheral Devices
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Solution Overview
Problem
Peripheral devices operating under the Bluetooth Low Energy standard face extended disconnect states when roaming between central devices, as they lack coordinated decision-making mechanisms to efficiently reconnect to new central devices.
Innovation Solution
A coordinated roaming system where central devices detect a peripheral's movement and perform coordinated sensing to determine the next suitable central device, using received signal strength indicators (RSSIs) to minimize connection latency, with the network controller configuring the system to ensure seamless handoff without additional software or hardware obligations on the peripheral device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If peripheral devices use standard BLE roaming procedures without coordination, then device complexity is minimized, but connection latency increases and disconnect time is extended
Solution Approach 1:
The patent introduces a coordinator device as an intermediary between the peripheral device and multiple central devices. The coordinator performs sensing operations to monitor signal strengths and manages the handoff process, reducing the peripheral's disconnect time without requiring the peripheral itself to become more complex. The coordinator acts as a mediator that coordinates sensing requests and manages connection state transitions.
Solution Approach 2:
The system performs preliminary sensing operations before the actual handoff occurs. The coordinator device proactively senses signal strengths from multiple central devices and prepares handoff information in advance. This preliminary action allows the peripheral device to transition to a new central device more quickly without extending its disconnect state, as the necessary information is already gathered and processed beforehand.
2Reliability
If multiple central devices perform coordinated sensing, then connection reliability is improved, but energy consumption increases
Solution Approach 1:
The patent implements partial sensing action where only the necessary central devices perform sensing operations. The coordinator device requests sensing from specific central devices based on the current connection state and peripheral location, rather than having all central devices continuously sense. This partial action maintains connection reliability by sensing only when and where needed, reducing overall energy consumption while ensuring reliable handoffs.
Solution Approach 2:
The peripheral device maintains its standard BLE operation and advertising mechanisms, essentially serving itself by continuing its normal function while the coordinator handles the sensing and coordination overhead. The peripheral doesn't need to participate in or provide additional functionality for the sensing process, maintaining its energy efficiency while benefiting from improved connection reliability through the coordinator's sensing operations.
Data Source
AI summary
A BLE system includes a network controller, peripherals, and central. As one of the peripherals begins to roam, the current central device in a connection with the peripheral detects when the peripheral device is moving away from the current central. Other centrals receive requests to perform coordinated sensing of transmissions from the peripheral device to the current central device. The coordinated sensing includes the other central devices monitoring transmissions from the peripheral device to determine respective received signal strength indicators (RSSIs) on at least one frequency corresponding to a frequency hopping pattern of the connection. The other centrals report the coordinated sensing results to the network controller which determines a next central based, at least in part, on the sensed RSSIs. The network controller sends blacklists to centrals that are not the next central and the peripheral disconnects from the current central, advertises, and reconnects with the next central.