LPWAN Duty Cycle Control for Confirmed Packet Retransmission
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Solution Overview
Problem
LPWANs operating in unlicensed frequency spectrum and using ALOHA-type transmission face high packet loss due to collisions and competition with other traffic sources, leading to inefficient network operations and challenges in controlling confirmed data packet retransmissions, which can exceed duty cycle limits and cause network congestion.
Innovation Solution
Implementing a method where network nodes send a first command packet to end devices setting a specific upper limit for the duty cycle of confirmed data packets, allowing end devices to transmit within this limit while unconfirmed data packets are not restricted by this limit, enabling better control over network traffic and reducing packet loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If end devices retransmit confirmed data packets without limit until acknowledgment is received, then reliability of data delivery is improved, but network congestion increases and duty cycle constraints are violated
Solution Approach 1:
The network server dynamically adjusts the retransmission parameter NbTrans for confirmed data packets based on network conditions, device behavior, and QoS requirements. This allows the system to maintain reliable data delivery while controlling the number of retransmissions to prevent network congestion and duty cycle violations.
Solution Approach 2:
The network server monitors network conditions, packet delivery success rates, and device retransmission patterns, then provides feedback by adjusting NbTrans values. This feedback mechanism enables the system to adapt retransmission limits dynamically, balancing reliability with network productivity.
2Reliability
If end devices transmit confirmed data packets frequently to ensure delivery, then data delivery reliability is improved, but gateway duty cycle constraints are exceeded
Solution Approach 1:
The network server controls the duty cycle impact by adjusting NbTrans parameters for confirmed packets, limiting the duration and frequency of transmissions. This ensures gateway duty cycle constraints are respected while maintaining acceptable delivery reliability through controlled retransmissions.
Solution Approach 2:
Instead of allowing unlimited retransmissions, the system applies partial action by setting reasonable limits on NbTrans. This partial control prevents excessive gateway activity and duty cycle violations while still providing sufficient retransmission opportunities for reliable delivery in most cases.
3Productivity
If network server controls retransmission count for confirmed packets, then network traffic is managed within duty cycle limits, but device complexity increases
Solution Approach 1:
The network server autonomously manages retransmission control by automatically adjusting NbTrans parameters based on monitored network conditions. This self-service approach simplifies the overall system by centralizing control logic in the server rather than requiring complex distributed control mechanisms at each device.
Solution Approach 2:
The network server performs multiple functions including packet routing, acknowledgment management, and dynamic retransmission control through a single centralized entity. This multi-functionality reduces device complexity by consolidating control responsibilities in the server that already handles other network management tasks.
Data Source
AI summary
The network system includes a network node and an end device. The network node is required to send a confirmation to the end device upon reception of a data packet of a first type and is not required to send a confirmation to the end device upon reception of a data packet of a second type. The method includes transmitting, by the end device, data packets of the first type in accordance with a duty cycle that is smaller than or equal to the first upper limit indicated by a first command packet received from the network node. The application further relates to a network node and an end device for use in a network system.