Weightless vs. LoRaWAN

LoRaWAN cannot support Firmware-Over-The-Air for real deployments because of downlink limitations. Learn Why.

How many devices does a single base station support in a large urban environment?

What is the coverage of a single base station?

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A key IoT network deployment requirement: bi-directional communication to upgrade firmware-over-the-air and update security patches to end-devices that have already been deployed in the field. 

 Bi-directional / FOTA 

The three reasons why LoRaWAN is unable to support Firmware-Over-The-Air (FOTA) for a real IoT deployment.

1. With very stringent downlink limitations, LoRaWAN would take an unreasonably long time to update the firmware for a single end device. There are a few elements to take into consideration including the distance of gateway to end device and spreading factor utilised but It could potentially take weeks to send a 200K update to ONE end-device given 20 bytes on a 5-minute polling. 

2. LoRaWAN gateway transmissions are uncoordinated. This means if a gateway attempts firmware downlink transmission, it will not be able to listen and receive messages from the rest of the end devices in the network. When you have thousands of end devices deployed, the end-devices won't know the gateway is conducting a firmware upgrade and all messages being sent will be lost. Class B a synchronous mode has a 128 second beacon period. 

3. LoRaWAN gateways are duty cycle limited. LoRaWAN gateways can only transmit 1% of the time (ETSI), and will need all of the downlink resource for acknowledgements and MAC control messages. Very, very little would be left over for FOTA multicast. In the US, the 1% duty cycle limit does not apply so the network basically stops functioning to facilitate uplink. 

 Weightless is a narrowband LPWAN technology which supports FOTA and true bi-directional communication. Duty cycle limitations do not apply as Weightless-P utilises spectrally efficient narrowband operation and frequency hopping. 

Capacity Comparison

How does a Weightless, LoRaWAN, and Sigfox base station perform when placed in a large, urban environment?

Our large urban area capacity simulation uses Hata to derive the path loss for a given base station to end device distance. Hata Model is the most widely used radio frequency propagation model for predicting the behaviour of cellular transmissions in built up areas.

Settings: Base Station Height = 30m

                End-Device Height = 0.5m

LoRaWAN settings:  adaptive data rate assumption given end nodes are spread uniformly throughout a large urban city (2km for EU and 4.5km for US). Thus, the closer nodes are using SF7 and farther nodes are using SF 12. The average data rate is 3200bps so about SF9 average. For optimal performance, LoRaWAN will be using 8 channels (1MHz bandwidth in EU) and 64 channels (8MHz in US).

Europe: 863-870 MHz

USA: 902-928MHz

Devices / Base Station Calculator (EU)

Inputs (left):

1. Use slider/manually input end-device message size

2. Use slider/manually input messages sent per day

examples:

every 15 mins = 96 messages / day

every minute = 1440 messages / day

Outputs (right): devices supported per base station

Devices / Base Station Calculator (USA)

Range Comparison

To most accurately/objectively compare range, we reference the technology's link budget. Link budget accounts for all of the gains and losses from the transmitter, through the medium (free space, cable, waveguide, fiber, etc.) to the receiver in a telecommunication system. It accounts for the attenuation of the transmitted signal due to propagation, as well as the antenna gains, feedline and miscellaneous losses.  We will consider 0dBi antennas (antennas with no gain) for direct comparison.
Tx Power: 14dBm in EU 868MHz, 27dBm in EU 169/876MHz,
30dBm in US 915MHz, 23dBm in Korea
Weightless Sensitivity: -134dBm @ 625bps
LoRaWAN Sensitivity USA: -130dBm; SF12 500kHz (980bps)
LoRaWAN Sensitivity EU: -132dBm; 250bps 
Tx Power - Sensitivity = Link Budget 
Weightless 
160dB
LoRaWAN
150dB
150dB =
~5km range in medium city
~25km range in rural area
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