Layer-Based Scheduling for Multi-Hop Wireless Networks
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Solution Overview
Problem
Existing multi-hop wireless networks face challenges in achieving low latency and high reliability due to limitations in scheduling complexity and interference in industrial applications, particularly in IEEE 802.15.4 standard solutions and Time-Slotted Channel Hopping (TSCH) MAC protocols, which are vulnerable to network dynamics and interference from other devices.
Innovation Solution
The proposed solution introduces a wireless device with a controller that determines schedules for transmitting and receiving messages based on layer ID, implementing opportunistic routing and channel hopping to reduce scheduling complexity and enhance communication reliability, while also using acknowledgement and overhearing mechanisms to prevent duplicate message transmission and adapt to network changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TDMA scheduling is used to avoid collisions and reduce latency, then communication reliability is improved, but the system becomes vulnerable to multi-path fading and interference from other devices
Solution Approach 1:
The patent implements periodic channel hopping where the communication channel changes at regular intervals according to a hopping sequence. This periodic switching allows the system to escape from multi-path fading conditions and interference by moving to different frequency channels over time, thereby maintaining communication reliability while avoiding the harmful effects of staying on a single congested or faded channel.
2Reliability
If TSCH MAC with channel hopping is used to avoid interference, then communication reliability is improved, but scheduling complexity increases
Solution Approach 1:
The patent segments the network into layers based on distance from the sink node, with each layer assigned specific transmission and reception timeslots. This segmentation simplifies scheduling by creating a structured hierarchy where nodes only need to communicate with nodes in adjacent layers, reducing the overall scheduling complexity while maintaining the reliability benefits of TSCH channel hopping.
Solution Approach 2:
The patent pre-assigns layer IDs to nodes and determines their transmission/reception timeslots based on these layer assignments before actual data transmission begins. This preliminary organization allows nodes to autonomously determine their scheduling without complex real-time negotiations, reducing scheduling complexity while ensuring reliable communication through predetermined time slots.
3Loss of time
If tightly scheduled communication is used to ensure determinism, then latency is reduced, but the network becomes vulnerable to network dynamicity such as variable traffic rates and node failure
Solution Approach 1:
The patent implements dynamic adaptation where nodes can change their layer assignments and timeslot allocations based on current network conditions such as traffic rates and node availability. This dynamic approach allows the network to maintain low latency by adjusting schedules in real-time while adapting to network dynamicity, overcoming the rigidity of tightly scheduled communication.
Solution Approach 2:
The patent incorporates feedback mechanisms where nodes monitor network conditions and adjust their transmission schedules accordingly. This feedback loop enables the network to respond to variable traffic rates and node failures by reallocating timeslots and channels dynamically, maintaining both low latency and adaptability simultaneously.
4Reliability
If dedicated routing paths are used to ensure deterministic communication, then reliability is improved, but scheduling complexity and control overhead increase
Solution Approach 1:
The patent creates a universal layer-based scheduling framework that applies to all nodes regardless of their specific routing paths. Each node follows the same rules for determining transmission/reception timeslots based on its layer ID, which simplifies scheduling complexity and reduces control overhead while maintaining reliable communication through the structured layer hierarchy.
Data Source
AI summary
There is provided a wireless device and a method for managing a wireless device for wireless transmission over a multi-hop wireless network, the wireless device comprising a wireless interface and a controller. A schedule of timeslots for transmitting and timeslots for receiving messages is determined based on which layer of the network the wireless device occupies. A transmission from a first node is received during a scheduled timeslot for receiving messages, the transmission comprising a message. The message is added to a queue of messages. In response to a signal being received via the wireless interface indicating that another node in the network has received the message, the message is removed from the queue of messages. During a scheduled timeslot for transmitting messages, at least one message from the queue of messages is transmitted to nodes in a layer closer to the sink than the wireless device.