BLE ACL Link Parking for Isochronous Collision Avoidance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In Bluetooth Low Energy (BLE) networks, over-the-air collisions and congestion often occur between asynchronous connection-oriented (ACL) and isochronous connections, particularly in piconets, which degrade the performance of applications like LE audio streaming.
Innovation Solution
The proposed solution involves temporarily deactivating or 'parking' the ACL link associated with an isochronous link in BLE piconets. This allows the ACL link to be activated only when necessary, reducing collisions by ensuring that ACL events are timed to avoid conflicts with isochronous events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ACL link is maintained active to transport control information and maintain clock synchronization, then reliability of link control is improved, but over-the-air congestion and collisions between ACL and CIS events increase
Solution Approach 1:
The ACL link is dynamically switched between active and parked states based on operational needs. When isochronous data transfer is required, the ACL link is parked to eliminate collisions. When control information needs to be transmitted, the ACL link is activated. This dynamic state change resolves the contradiction by making the system adaptable to different operational requirements.
Solution Approach 2:
The ACL link is activated periodically only when control information needs to be exchanged, rather than remaining continuously active. This periodic activation reduces the time the ACL link occupies the air interface, thereby reducing opportunities for collisions with CIS events while still maintaining necessary control functionality.
2Ease of operation
If the ACL link is kept active for continuous control information transport, then ease of operation is improved, but bandwidth available for isochronous link decreases
Solution Approach 1:
The control information transport function is extracted from the continuously active ACL link and is instead performed through periodic activations of the ACL link during designated subevents. This extraction allows the majority of time to be dedicated to isochronous data transfer while control functions are still fulfilled when needed.
Solution Approach 2:
Control information is transported periodically through scheduled ACL events rather than continuously. This periodic transport mechanism reduces the time occupation of the ACL link, thereby increasing bandwidth availability for isochronous links while still maintaining the ability to transport control information when required.
3Speed
If ACL events are scheduled frequently to ensure timely control information exchange, then responsiveness is improved, but collisions with isochronous events increase
Solution Approach 1:
The frequency of ACL events is dynamically adjusted based on the operational state. When isochronous data transfer is the priority, ACL events are parked or minimized. When control information exchange is urgent, ACL events are activated with appropriate frequency. This dynamic adjustment resolves the contradiction by adapting event frequency to current operational requirements.
Solution Approach 2:
The system preliminarily determines the operational state and accordingly decides whether to activate or park the ACL link before control information exchange is needed. This preliminary decision-making prevents collisions by ensuring ACL events are only scheduled when isochronous events are not occurring, thereby maintaining responsiveness without causing collisions.
Data Source
AI summary
Disclosed are techniques to temporarily deactivate or activate the ACL link associated with an isochronous link between a central and a peripheral device of a BLE piconet. The central and peripheral devices may agree to enter into an ACL parked mode after an isochronous link is established between the devices. In the parked mode, the ACL link is in a dormant state without any ACL events. If the central or the peripheral device wants to activate the ACL link to transmit one or more control or data packets, the device may use a CIS subevent on the isochronous link to transmit an LL control PDU. The LL control PDU may contain ACL timing information that specifies the timing of the future ACL event. The device may specify the ACL timing information to avoid or reduce chances of collisions of the future ACL event with CIS packets on the isochronous link.