Deep indoor penetration and propagation breakthrough inside confined spaces
Combining Cellular IoT and LoRaWAN for telecom deep indoor penetration and propagation in the nuclear industry
Framatome (the components manufactured by Framatome equip more than 100 nuclear reactors in 11 countries) and Intellinium have just demonstrated that it is possible to bring substantial extra safety to workers operating in very challenging confined spaces (such as nuclear steam generator) by ensuring telecom deep indoor penetration and propagation leveraging small form-factor smart PPE wearable.
Intellinium Safety Pod (about 80 g) features multiple telecom protocols and frequencies which can be used to establish a communication between the Safety Pod and the Rescue Chain : 4G NB-IoT, 4G LTE-M, Bluetooth Low Energy, LoRaWAN.
4G LTE-M and 4G NB-IoT have shown very good indoor penetration (concrete walls) and indoor propagation (entering into a “hole” and propagating along the metallic elements). From this field test, and also based on other tests we have carried out in French industrial sites, we can say that in most of cases NB-IoT and/or LTE-M will work fine to bring deep indoor penetration.
For very thick concrete walls and/or deep undergound areas where NB-IoT might meet telecom deep indoor penetration issues, we have tested a fall-back scenario by using LoRaWAN (with the band 868 MHz in France). With a simple and cost-efficient combo gateway/8 dBi antenna placed in a production site, we have demonstrated that we could penetrate reinforced concrete walls of about 3 m! That’s pretty amazing, especially when we measured about a RSSI signal strength of about -120 dBm which leaves room for extra peneration (about an extra of 15 dB).
We have also shown that the use of Bluetooth beacons is possible in those confined spaces allowing highly valuable relative positionning. Said differently, not only it’s possible to send/receive alert notification from the worker smart PPE but we can also give the Rescue Chain a pretty accurate location about where the worker is. Nevertheless, Bluetooth 2.4 GHz is definetely not the best frequency for confined spaces and the goal here is really to “tag” some dangerous machines and/or tag areas BUT not to use Bluetooth to communicate. One exception could be to use direct Safety Pod <- > Safety Pod communication to notify a worker that one of his colleague nearby requires immediate assistance (from a technical perspective, it’s the Bluetooth advertising feature).
Last but not the least, cellular IoT cell towers might be unavailable (pretty often actually if we look at the real figures), and LoRaWAN might be a good fall-back mechanism, especially if combined with multi-SIM equipment. We offer all those features in our smart PPE.
Highly constrained smart PPE and LoRaWAN gateway allowing telecom deep indoor penetration
What might be even more impressive is the form factor and the power efficiency of all the material used:
- The Safety Pod is a lightweight and higly power effficient smart PPE (Personal Protective Equipment) which can last easily several weeks. We have embedded a solar pannel which can greatly help to achieve even more battery life.
- The LoRaWAN gateway can be optimized to be “fueled” by a solar pannel (it’s now what we have to work on) if located outdoor. In case of massive power outage within an industrial site, it could be very valuable to have a telecom solution which can operate without powerplug. Using a small external battery combined with the solar pannel is almost mandatory as it’s not acceptable not to operate the local telecom network during the night!
Confined spaces are one of the riskiest places to work on
A confined space is an area which is both enclosed, or largely enclosed, and which also has a reasonably foreseeable risk to workers of fire, explosion, loss of consciousness, asphyxiation, fall or drowning.
By definition, those areas are very risky even though also very controlled. Some of those areas might be ATEX zones (explosive environment) but most of them are not. Intellinium complies with Zone 1 and Zone 2 requirements.
Confined spaces can be found in almost any industry with people operating alone or in group. It’s not recommanded to work alone in this type of environement but even group working might bring some short-time lone working.
Connected worker solutions such as our smart PPE can greatly help to protect workers in confined spaces allowing bi-directionnal panic button, man-down, mass emergency notification, incoming notification, etc…
Telecom deep indoor peneration is a game-changer to better protect workers operating in confined spaces
What we have demonstrated with Framatome last week opens new fields of research as well as bring immediate benefits for workers protection in confined spaces. Our equipment is expected to be mass-produced in 2022 featuring all conformity levels and certifications.
Since our inception in 2009, we have been pushing the limits for better protecting and saving workers. Tackling telecom issues whenever wherever is a major keystone. We have still some room for improvements and still some challenges to solve but we can say that since last week, we have opened new concrete opportunities and defintely pushed the boudaries of what is possible.
Some limitations due to 868 MHz regulatory 1% duty cycle
There are some intrinsic limitations when using LoRaWAN, mainly due the 1% duty cycle which :
- Limits severely the number of messages which can be sent from the pod per day (uplink). If you use LoRAWAN as a fall-back telecom protocols, it’s not really an issue as you do not expect all your smart PPEs to trigger man-down alerts !
- Even more limits dramatically the number of messages which can be sent to the pod per day (downlink). Once you have hundreds of smart PPEs communicating in LoRaWAN, it becomes almost impossible to use the donwlink channel, for instance for Mass Emergency Notification. Nevertheless, using a very rare downlink message to notify someone that one of his colleagues nearby is in critical situation can be done and brings a lot of safety value when there is no cellular network coverage.
Other limitations due to the crowded LPWAN 868 MHz (theoritical)
Another limitation is due to the intrinsic nature of ISM (Industrial, Scientific and Medical) bands which allows anyone to open its own local network. By doing that, it increases a lot the likelyhood of interferences and LoRaWAN networks might dramatically suffer from massive network co-existence. This problem should not impact a lot industrial sites as they are private areas. Each organisation can limit the number of gateway/antenna to be sure to limit interferences. In theory, one gateway could handle up to 2000 objects. Therefore, it’s should not be an issue for industrial sites expect maybe for those sites located in densely urban areas.
Open question related to LoRaWAN satellites communication and confined space
One interesting question is related to LoRaWAN available through satellites. Said differently, will satelites communication allow confined spaces bi-directionnal telecom deep indoor penetration ? First answer would be no but we believe that it’s not black or white. In some cases, the radio signal could propagate through metalic infrastructure up to the confined space !