Conduit AEP: Convert to Basic Packet Forwarder

This section describes using LoRa Packet Forwarder Mode.

When forwarding packets to another Conduit be sure the receiving end has the firewall opened to receive incoming connections.

If you are using Cellular as WAN:

  • Before activating this mode, change the keep alive interval to 1 second within the Packet Forwarder application (keepalive_interval in the config file). This decreases the latency of packets over the radio enough to allow the return packet from the network server to get to the lora radio before its timestamp expires.
  • Excellent signal strength is also required to keep latency low enough for this mode to work.

To activate LoRa Packet Forwarder Mode:

  1. Under LoRaWAN > Network Settings,  select PACKET FORWARDER  under Mode. For details, see LoRaWAN Network Settings.
  2.  In the Config text field, enter the contents of your custom global_conf.json file.
  3. basic_pkt_fwd runs unless fake_gps parameters are included, in which case gps_pkt_fwd runs (for location use ref_latitude, ref_longitude and ref_altitude settings).
  4. Verify that the text field contents match the proper json format. Click Submit.
    •  The GUI passes the .json file to the packet forwarder application.
    •  If successful, a message displays LoRa settings successfully updated.
    •  If the format is incorrect, a message displays Invalid JSON input.

 

AS923-Japan Settings for Packet Forwarder GUI
  • Enable LBT: checked
  • LBT RSSI Offset: -4 dB
  • LBT RSSI Target: -80 dBm
  • ScanTime: 5000 us
  • Auto LBT Channels: checked

 

For Conduits with GNSS module installed

gpsd usage of the GPS is not compatible with lora-packet-forwarder. It is not possible to use the Multitech supplied Lora-Packet-Forwarder with the GNSS port, and GPSD at the same time.

  1. Edit /etc/default/gpsd
  2. Set Enabled=”no” and Save
  3. ntpd must be disabled or configured to not use gpsd
    • Edit /etc/default/ntpd, set Enabled=”no” and Save

    Or

    • Edit /etc/default/ntpd, set GPSD_REQUIRED=0 and Save
    • Configure NTP time server in /etc/ntp.conf
  4. Set “gps_tty_path”: “/dev/ttyXRUSB2″ in global_conf.json “gateway_conf” section
  5. Reboot

 

Semtech Demo Server

Use the following settings to forwarder packets to Semtech Demo IOT servers.
• North America Instance: https://na.iot.semtech.cloud
• Europe Instance: https://eu.iot.semtech.cloud
• China Instance: https://cn.iot.semtech.cloud
• Asia Pacific (excludes China): https://apac.iot.semtech.cloud


"server_address": "52.3.215.147",
"serv_port_up": 20000,
"serv_port_down": 20000



Packet Forwarder Configuration Options

Two sections are available in the configuration: radio settings (SX1301_conf) and server settings (gateway_conf).

SX1301_conf

  • lorawan_public – set sync word to false: 0×12 or true: 0×34
  • clksrc – must be 0 for Multitech gateway hardware
  • antenna_gain – configure the installed antenna gain if the network server sends EIRP value with downlinks. The Multitech network server will account for antenna gain before sending tx power to the forwarder.

Radios

The radio_0 and radio_1 settings configure the two front-end radios on the MTAC cards.
enable – true if radio is enabled for use

  • type – type of radio chip installed SX1257 or SX1255, frequency range differs
  • freq – center frequency the radio is configured to listen for packets
  • tx_enable – true if radio can be used for transmissions
  • tx_freq_min – minimum frequency to be allowed for transmissions
  • tx_freq_max – maximum frequency to be allowed for transmissions
  • rssi_offset – offset in dBm to adjust the radio RSSI reading

Channels

Eight channels can be configured to receive LoRa packets using 125 kHz bandwith. These channels are configured in the chan_multiSF_x settings. Each channel has an enable boolean, a selected radio and an intermediate frequency. The channel frequency will freq setting of the radio plus the if setting of the channel.

  • enable – true if this channel is enabled for use
  • radio – selected radio to listen for packets
  • if – intermediate frequency offset applied to the selected radio “freq” setting



Two additional channels can be configured with the chan_Lora_std and chan_FSK settings.

  • enable – true if this channel is enabled for use
  • radio – selected radio to listen for packets
  • if – intermediate frequency offset applied to the selected radio “freq” setting
  • bandwidth – channel bandwidth
  • spread_factor (LoRa) – channel spreading factor (7-12)
  • datarate (FSK) – channel datarate in bps

Look-up-table (LUT)

There are sixteen power settings that can be configured, these settings have been selected during calibration for each hardware. The power sent from the network server is looked up in this table by the rf_power setting. The corresponding pa_gain, mix_gain and dig_gain settings are then input into the radio for the transmission. These settings should not be adjusted.

gateway_conf

  • gateway_ID – gateway identifier sent in each message to the network server
  • server_address – address of the network server
  • serv_port_up – port for sending uplink packets to the network server
  • serv_port_down – port to communicate to receive downlink packet from the network server
  • keepalive_interval – interval to ping the network server
  • stat_interval – interval to send stat messages to the network server
  • push_timeout_ms – socket timeout when publishing messages to the network server
  • autoquit_threshold – number of keepalive messages without response to wait before quitting
  • forward_crc_valid – enable to forward valid packets to the network server, default: true
  • forward_crc_error – enable to forward CRC failed packets to the network server, default: true. The network server will reject packets with failed CRC, it may not be necessary to forward the packets except for a statistic of local RF quality or to monitor the gateway performance over time. Some random CRC failed packets are expected to be received from random noise.
  • forward_crc_disabled – enable to forward packets without CRC enabled to the network server, default: false. LoRaWAN protocol expects uplink packets to have CRC enabled.

Listen Before Talk configuration