BLE Roaming Handoff Using Coordinated RSSI Evaluation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Peripheral devices operating under the Bluetooth Low Energy standard face extended disconnect states when roaming between central devices due to lack of coordinated decision-making, leading to increased connection latency.
Innovation Solution
A network controller coordinates roaming decisions by monitoring RSSI signals from peripheral devices and determining the most suitable next central device through coordinated air monitoring among multiple central devices, facilitating seamless handoff without additional software or hardware requirements on the peripheral.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a peripheral device roams between central devices using conventional BLE connection methods, then the peripheral can move between different central devices, but the disconnect time is extended due to lack of coordinated handoff evaluation
Solution Approach 1:
The system performs preliminary actions by initiating advertising scan requests and evaluating signal strengths from multiple central devices before the actual handoff occurs. The current central device sends a request to the peripheral to advertise, and other central devices prepare to scan and evaluate signals in advance, so when handoff is needed, the decision can be made quickly based on pre-collected information.
Solution Approach 2:
The network controller acts as an intermediary that coordinates the roaming process. It receives signal strength information from multiple central devices, determines the most suitable target central device, and manages the handoff process. This intermediary coordinates the actions of current and target central devices, reducing the complexity that would otherwise need to be handled by each individual device.
2Reliability
If the peripheral device continuously monitors and evaluates multiple central devices for handoff, then handoff decision accuracy is improved, but energy consumption increases
Solution Approach 1:
The current central device initiates the advertising request to the peripheral, and the peripheral responds by advertising. This self-service mechanism allows the peripheral to provide signal strength information to multiple central devices without requiring active scanning or continuous monitoring by the peripheral, thereby reducing its energy consumption while still enabling accurate handoff decisions.
Solution Approach 2:
Instead of continuous monitoring, the system uses periodic advertising and scanning actions. The peripheral advertises at intervals when requested, and central devices scan periodically to evaluate signal strengths. This periodic approach reduces energy consumption compared to continuous monitoring while maintaining sufficient accuracy for handoff decisions.
3Speed
If multiple central devices perform coordinated air monitoring and signal strength evaluation, then handoff speed is improved, but system complexity increases
Solution Approach 1:
The coordinated monitoring system is segmented into distinct functional components: the current central device that initiates the process, other central devices that scan and evaluate signals, and the network controller that aggregates information and makes the final handoff decision. This segmentation allows each component to perform its specific function efficiently without requiring all devices to have full coordination capabilities, thereby reducing overall system complexity while maintaining fast handoff speed.
Data Source
AI summary
A BLE system includes a network controller, peripherals, and centrals. As one of the peripherals begins to roam, the current central in a connection with the peripheral detects when the peripheral device is moving away from the current central and reports the roaming to the network controller. The peripheral receives a request from the current central to advertise for handoff evaluation during the connection and the other centrals receive requests from the network controller or from one or more of the centrals to scan for handoff evaluation purposes. The centrals determine the received signal strength from the received advertising packets and send the received signal strengths to the network controller. The network controller determines a next target central based on the received signal strengths. The network controller then causes the peripheral to disconnect from the current central and the current central advertises and establishes a connection with the next target central.