Overview
- 600 bps data rate, DBPSK
- allows greatly increased link budget (150-160 dBm, 10-15 km range in urban)
- Very long range, 10+km communication
- Star-topology networks with always-listening gateways (any number of low-power end devices)
- Uplink focused communication
- Very low-rate metering
- Unlicensed-band communication (902-928 MHz in US)
- Ultra-narrowband 600 Hz channel bandwidth
- Improves signal-to-noise ratio
- Detection only needs to occur at very specific frequency
- Downlink: 1.5 kHz bandwidth, 600 bps, GFSK
MAC
- ALOHA style access control (send whenever, no Acks)
- messages can be sent three times for increased reliability
+---------+---------+--------+---------+-------------+-----+
|Preamble |Frame | Dev ID | Payload |Msg Auth Code| FCS |
| (19) |Sync (29)| (32) | (0-96) | (16-40) | (16)|
+---------+---------+--------+---------+-------------+-----+
Uplink Frame Format
- Up to 29 bytes per packet, payload up to 12 bytes
- Preamble + Frame Sync are really a 6 byte field for radio sync
- Auth: 2-5 bytes
- Frame Check Sequence (FCS): 16-bit CRC We get faster bitrate in the US, since 600 bps 0.387 seconds in the air. The maximum dwell time for 915 MHz is 400 ms.
+---------+---------+-------+---------+-------------+-----+
|Preamble |Frame | ECC | Payload |Msg Auth Code| FCS |
| (91) |Sync (13)| (32) | (0-64) | (16) | (8) |
+---------+---------+-------+---------+-------------+-----+
Downlink Frame Format
- Similar structure, 28 bytes total, payload up to 8 bytes
- Larger preamble + frame sync of 13 bytes
- Error Correcting Code (ECC) for increased reliability
Sigfox Status
Mostly abandoned the US. Filed for bankruptcy and purchased by another company.