LoRa bike race tracker

mountain bike tracking system for off-grid out-of-gsm coverage races

Bike Hardware:

Semtech LoRa SX1276?
uBlox GPS
LiPo charger or DC-DC converter for 8.4v bike light battery pack passthrough.
Arduino Pro Mini or Teensy controller for logic - possible soft-mesh LoRa mesh for greater range?
(or module like Dorji HopeRf Motronics etc)

Base Station Hardware

RaspberryPi as AccessPoint, serving locally stored OSM map tiles for relevant area. Wifi Captive Portal serving OSM with markers via HTML5 allows any device to view map and locations.
If base station has 3g/gsm/wifi capability, option to upload positions to internet KML or similar for public viewing.
Possibly remote relay station solar powered with Yagi backhaul
if LoRaWan, then SX1301 receiver board

Protocol

Support for 100's devices - SODTMA-like self organising or smart-beaconing of position, or base-polled?
AIS-like sentences for identifying devices and position/speed information, possibly battery level too. AIS data format would allow integration with OpenCPN quite easily for mapping and standard libraries.
So would NMEA0183 spat transparently from GPS, with custom NMEA sentence for battery information, panic buttons etc

NMEA max chars in sentence is 82 (inc CRLF)
the maximum packet length is 256 bytes in LoRa mode.
125KHz BW, coding rate=1. 82byte payload, 6 byte preamble +CRC

		spreading factor
		9	10	11	12
time on air (ms)		545	968	1773	3219
rx sens (dBm)		-127	-130	-132.5	-135

SF 10 for 125Khz BW would give ~ 1s transmission which should be fade resistant.
1 minute updates would give 60 clients per channel. 8 channels = 420 clients with no overlapping. 49 channels (SX1301)=2940 clients@1 minute updates. ~300 clients @ 10s resolution. Improved with adaptive packet rate controlled via LoRaWAN
GPS synchronised packet transmission. assuming no mesh.
Alternatively set up LoraWAN and use adaptive data rate determined by basestation.

links

http://air.imag.fr/index.php/LoRa
https://www.loriot.io/gateways.html
http://www.calao-systems.com/products/archipel-lora-network/archipel-toti/archipel-toti-lora-pico
http://www.daveakerman.com/
https://github.com/dbrooke/lora-gateway
http://openlora.com/forum/viewtopic.php?f=4&t=36