Table of Contents:

• 1.  Definition for LoRaWAN Repeater
• 2.  Uplink Data Challenge
• 3.  Downlink Data Challeng
• 4.  Channel Challenge
• 5. Limited LoRaWAN Relay Solution

1.  Definition for LoRaWAN Repeater

A requirement for LoRaWAN repeater is as below:

2.  Uplink Data Challenge

When there are uplink data from End Node, Repeater needs to get these packets and uplink to LoRaWAN Gateway. Then LoRaWAN Gateway uplinks the data to LoRaWAN Server. There will have below influence & Requirements:

• A repeater is normally made by LoRaWAN Gateway which has 8 x RX channels and 1 x TX channel, When the repeater sends a packet to LoRaWAN gateway, it will use the TX channel. During TX time, RX channel will be disabled, the TX time is short but still has some influence on the capacity for end nodes.
• Repeater software should be changed so it can send out the received packet from the End node and send out a packet that the LoRaWAN gateway can receive.

3.  Downlink Data Challeng

LoRaWAN Downlink has strict timing as below. The downlink packet must arrive end node exactly within the RX window with the correct Frequency & DR. If the downlink packet doesn't arrive within the RX window, the end node will not able to get the downlink so it fails on OTAA process and accept normal downlinks for network control.

In the general LoRaWAN network for the Class A end node, the LoRaWAN server will send the downlink once it gets the uplink from end node, together with this downlink packet, LoRaWAN server will also set a RECEIVE_DELAY parameter, When the gateway gets this packet, gateway won't send out the packet immediately, gateway will send after RECEIVE Delay to ensure LoRa packet can arrive end node in the match time window.

So there are challenges as below:

• The repeater should be able to get the rx packet from Gateway and sends out the packet exactly. A driver needs to modify for this purpose.
• The gateway must send out two downlink packets:
  • First Packet should be sent immediately so the repeater has enough delay to send to end node.
  • The second packet sends as usual so the nearby end node can receive it.

4.  Channel Challenge

Due to IQ invert and Channels asymmetric (Uplink and Downlink use different channels in US915, AU915 etc.) Two repeaters are required: one for Uplink and one for Downlink,

5. Limited LoRaWAN Relay Solution

See: http://wiki.dragino.com/xwiki/bin/view/Main/User%20Manual%20for%20All%20Gateway%20models/LoRaWAN%20IoT%20Kit%20v3%20User%20Manual/#H7.Example6:LimitedLoRaWANrelay