Bluetooth Sensor Network Collision Reduction via PAwR Slot Assignment
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Solution Overview
Problem
Bluetooth Mesh networks experience packet loss due to the lack of collision detection or avoidance techniques, leading to congestion and increased losses in dense networks, especially when operating on shared Bluetooth Low Energy advertising channels.
Innovation Solution
Implementing Periodic Advertising with Response (PAwR) in Bluetooth wireless sensor networks, where each sensor device is assigned a specific response slot to transmit measurement data, reducing collisions by synchronizing transmissions and using a relay device to compile and forward data to the next hop device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Bluetooth Mesh transmitters use randomized delay intervals to repeat transmissions, then packet loss is reduced in sparse networks, but network congestion increases and packet loss worsens in dense networks
Solution Approach 1:
The network transmissions are segmented into distinct collision-free time slots, with each sensor device assigned a specific slot for transmitting sensor status messages. This segmentation eliminates the need for randomized retransmissions while ensuring reliable packet delivery, as devices transmit at predetermined times rather than competing for channel access.
Solution Approach 2:
Sensor devices transmit sensor status messages at periodic intervals during their assigned time slots rather than using randomized delay intervals. This periodic transmission pattern ensures consistent packet delivery while maintaining predictable network traffic flow, preventing the congestion that arises from repeated randomized retransmissions.
2Speed
If multiple sensor devices transmit simultaneously on shared Bluetooth Low Energy advertising channels, then transmission speed increases, but collision probability increases leading to packet loss
Solution Approach 1:
The shared advertising channel is segmented into multiple time slots, with each sensor device assigned a specific slot for transmission. This allows multiple devices to transmit simultaneously at different times without collision, maintaining high transmission speed while ensuring packet delivery reliability through collision-free communication.
Solution Approach 2:
The system dynamically assigns time slots to sensor devices based on their identification or configuration, allowing the network to adapt transmission schedules to the specific composition of devices. This dynamic slot assignment optimizes channel utilization while preventing collisions, balancing speed and reliability.
3Ease of operation
If sensor devices transmit sensor status messages at random times, then transmission simplicity is maintained, but collision probability increases in dense networks
Solution Approach 1:
Time slots are preliminarily assigned to sensor devices during network initialization or configuration, establishing a predetermined transmission schedule before actual data transmission begins. This preliminary arrangement maintains operational simplicity for individual devices while ensuring collision-free communication through pre-coordinated transmission times.
Solution Approach 2:
The relay device provides feedback by acknowledging received sensor status messages and managing the time slot assignments. This feedback mechanism ensures that devices transmit at the correct times without requiring complex collision avoidance logic, maintaining simplicity while improving reliability through centralized coordination.
Data Source
AI summary
A system and method for reducing the probability of collisions in a Bluetooth wireless sensor network is disclosed. The system and method utilize Periodic Advertising with Response to receive status information from the plurality of wireless sensor devices. Therefore, rather than sending the Sensor Status message at random times, the wireless sensor devices are all assigned a response slot in one of the subevents. The relay device receives all of the sensor status messages and forwards the information to the next hop device using measurement collection packets. In some embodiments, the relay device compacts the information before transmitting the measurement collection packets.