Packet Delivery Ratio (PDR)

What is the packet delivery ratio?

In wireless networks, particularly LoRaWAN®, the packet delivery ratio (PDR) is a metric that indicates the successful delivery of data packets from the sender to the receiver. It refers to the percentage of packets reaching their intended destination without errors or loss.

How does the packet delivery ratio work?

We need to delve into the underlying LoRaWAN® technology to understand how the PDR works. LoRaWAN® is a low-power, wide-area network protocol for long-range communication between network devices with low data rates.

Within the LoRaWAN® network infrastructure, nodes send data packets to a central gateway that bridges the nodes and the internet. These packets travel over the airwaves and can encounter various challenges, such as interference, signal fading, or obstacles.

When a node sends a packet, it expects an acknowledgement (ACK) from the gateway to confirm successful reception. If the packet is received correctly, the gateway sends the ACK, increasing the PDR. On the other hand, if the packet is lost or corrupted during transmission, no ACK is received. It results in a decrease in the packet delivery ratio.

The PDR is calculated by dividing the number of successfully received packets by the total number of packets sent and multiplying by 100 to get a percentage. For example, if 90 out of 100 packets reach their destination, the packet delivery ratio is 90%.

How does the packet delivery ratio compare to throughput?

While the packet delivery ratio measures the success rate of packet delivery, throughput refers to the amount of data that can be transmitted over a network within a given time frame.

The PDR focuses on packet transmission reliability by measuring the successful delivery of individual packets. On the other hand, throughput considers the overall efficiency of data transmission by measuring the total amount of data transferred during a specific duration.

Although related, the packet delivery ratio and throughput provide different insights into network performance. A high packet delivery ratio indicates a reliable network with minimal packet loss, ensuring data is transmitted successfully. Conversely, a low packet delivery ratio signifies a network with poor reliability, potentially leading to delays or incomplete data transmission.

Conversely, throughput considers packet size, network bandwidth, and congestion. A high throughput implies a network that can efficiently handle a large volume of data within a given amount of time.

Ultimately, the packet delivery ratio and throughput are crucial in evaluating LoRaWAN® network connectivity and detecting performance issues. While the packet delivery ratio focuses on the reliability of individual packet transmission, throughput provides a broader measure of the network’s overall capacity.

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