Parent Device Allocates Retransmit Slots for Peer Child Devices
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Solution Overview
Problem
Deterministic networks, such as IPv6 Time Slotted Channel Hopping (6TiSCH) networks, face challenges in ensuring reliable packet delivery due to the stringent requirements of minimal jitter and low latency, particularly in resource-constrained environments like Low Power and Lossy Networks (LLNs), where packet loss and retransmissions can occur without effective mechanisms for spatial diversity.
Innovation Solution
A parent network device allocates retransmit slots to child network devices within a channel distribution chunk, enabling them to retransmit data packets on behalf of peer devices that fail to receive acknowledgments, thereby introducing spatial diversity and minimizing interference by appropriating channel distribution chunks within an interference domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a parent network device allocates retransmit slots to child devices for peer retransmission, then packet delivery reliability is improved through spatial diversity, but network device complexity increases due to additional slot allocation mechanisms
Solution Approach 1:
Child devices are assigned multiple roles: they function as both their own transmission nodes and as relay nodes for peer devices. The same child device can transmit its own data and retransmit peer data using allocated retransmit slots, eliminating the need for separate relay devices and reducing overall network complexity while improving reliability through spatial diversity
Solution Approach 2:
The parent network device performs preliminary allocation of retransmit slots to child devices before actual data transmission occurs. This advance allocation establishes a structured retransmission framework that automatically activates when needed, reducing the complexity of real-time decision-making while ensuring reliable packet delivery
2Reliability
If retransmissions are performed by peer child devices using allocated slots, then packet loss is reduced through alternative transmission paths, but network latency increases due to additional retransmission hops
Solution Approach 1:
The network operates with periodic slotframes containing dedicated retransmit slots at predetermined intervals. This structured periodic approach allows the system to balance retransmission opportunities with latency constraints, as devices know in advance when retransmission slots occur and can plan their transmission schedules accordingly
Solution Approach 2:
When a child device successfully receives a data packet, it creates a copy that can be retransmitted to the parent device on behalf of the original transmitting child. This copying mechanism enables spatial diversity for packet loss reduction while maintaining efficient single-hop transmission paths, minimizing additional latency
3Adaptability or versatility
If child devices are enabled to detect and retransmit peer packets, then network adaptability is improved through dynamic retransmission capabilities, but energy consumption increases due to enhanced monitoring and transmission activities
Solution Approach 1:
Child devices perform partial monitoring of the wireless medium, focusing specifically on detecting data packets and acknowledgment status rather than comprehensive network monitoring. They activate retransmission functionality only when needed (when peer packets are detected without acknowledgment), reducing energy consumption compared to continuous full-network monitoring while maintaining high adaptability
Solution Approach 2:
The network system uses its own child devices to perform retransmission services for peer devices, eliminating the need for external relay nodes or additional network infrastructure. This self-service approach enhances adaptability by utilizing existing network resources while avoiding the energy overhead of dedicated relay devices
Data Source
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AI summary
In one embodiment, a method comprises receiving, by a parent network device in a wireless deterministic network, a retransmit capabilities message from a first child device attached to the parent network device, the retransmit capabilities message specifying that the first child device can detect a data packet transmission to the parent network device by a second child device attached to the parent network device and that is a peer of the first child device; and allocating, by the parent network device, a peer retransmit times lot to the first child device from within a channel distribution chunk appropriated by the parent network device, the peer retransmit timeslot enabling the first child device to retransmit a data packet on behalf of the second child device to the parent network device.