LoraWAN gateways require the use of a costly powerful data-crunching hardware composed of a chipset with dedicated DSP, analog and digital frontends. By contrast, PicoPlugs have a much simpler hardware based on the same LoRa transceivers as used in end-devices. A PicoPlug is intended to serve hundreds of end devices in the framework of a mostly synchronous star network.
At a given time, a PicoPlug can only monitor one communications channel with a given frequency, bandwidth and modulation (SF defining data rate). At first sight, this may appear as a handicap in terms of network capacity but in actual fact this handicap is amply counterbalanced as explained in the following.
PicoWAN and LoRaWAN exhibit similar maximum link budget which determines the maximum range between gateway and end device. Actually PicoWAN’s link budget is greater than LoRaWAN’s by a few dB. This is because PicoWAN resorts to using lower frequency bandwidths when needed whereas LoRaWAN is limited to a single bandwidth, i.e. 125 kHz. The narrower the bandwidth, the longer the range. Reducing the bandwidth may drastically improve the range.
Therefore if you set up a PicoWAN gateway side by side to a roof-top LoRaWAN gateway, the area covered is likely to be quite similar is spite of the LoRaWAN’s antenna being taller, the antenna length improving only marginally reception (not emission limited by regulations).
Because PicoPlugs are located indoor, more gateways will be needed to cover the same outdoor areas as telcos’ rooftop gateways. A few times more PicoPlugs are needed for the same coverage at street level, provided they are reasonably located high enough inside buildings and nearby windows. But because PicoPlugs are very cheap and easy to install, you will get a very good deep-indoor coverage that rooftop gateways will never achieve because PicoPlugs irradiate buildings from within.
Thanks to the clever PicoWAN protocol, transmission is always tuned to the best matching speed and power taking into account the instant conditions of the radio channel.
With PicoWAN all messages are automatically acknowledged (ACKed) by the network and can be repeated until they are dully received. In contrast to other LPWANs, PicoWAN is designed to ACK every message at no extra fee: Sigfox has no ACK capability and the issue with LoRaWAN is that, by construction, downlink is subject to restrictions mostly due to the impossibility of receiving uplink messages while downloading (uplink messages are lost).
At a given time, a PicoWAN gateway can only monitor one communication channel with a given frequency, bandwidth and spreading factor (data rate). At first sight, this may appear as a handicap in terms of network capacity but in actual fact this handicap is amply counterbalanced by the following factors:
PicoWAN MAC makes an optimum use of air time on the unique channel open at a given time so as to ensure a good synchronization of packets uploaded from end-devices. The maximum capacity on this unique channel is therefore far better than the ratio of 1 to 8, 8 being the number of channels that can be processed in parallel by LoRaWAN gateways.
PicoWAN MAC is organized in a fashion that allows for the co-existence of tens of gateways active in the same area without interfering, so that the number of gateways can be increased as needed to meet any network capacity requirements locally. Uplink and downlink messages are all synchronized and distributed amongst the 32 channels used by PicoWAN so that they do not interfere and make an optimum usage of air time.
PicoWAN gateways can be made very cheap, actually as cheap as end-devices with no infrastructure cost, and distributed virtually anywhere over a territory so as to meet any capacity requirements and reach the deepest indoor areas.
By contrast, LoRaWAN MAC relies on an Aloha transmission scheme in which each end-device can send a message at any time without any form of synchronization picking up at random one of the eight channels available. This simple scheme is naturally prone to collisions. If the message fails to be received at the destination, most of the time it will be lost because LoRaWAN message acknowledgement is hardly implemented in practice due to severe limitations in downlink capacity as explained in the foregoing.
Although LoRaWAN allows for bi-directional communication, downlink from the gateway to end-devices is severely limited by the fact that a downlink communication taking place with some end-device precludes any uplink communications from all other end-devices at the same time (even with 2 antennas). The receivers are blinded by antenna emission which means that all uplink messages sent concomitantly will be lost. Another limitation results from regulatory restrictions on network occupancy with duty cycle typically limited to 1% of air time, which is very little to serve thousands end-devices. Therefore in practice, LoRaWAN operators have to limit the number of downlink messages to the strict minimum and impose high fees on downlink messages compared to uplink.
Before uploading a message, a PicoWAN end device first scans a dedicated beacon channel to detect the gateway with the best signal strength (RSSI) around. Every second, each PicoWAN gateway every second emits a signal burst in the form of a “ping” which is about the shortest LoRa signal possible as well as the most powerful compliant with regulations. On average an end device will scan the beacon channel for half a second before it will upload a message using one of 32 channels.
This scheme ensures that the end device is able to assess the quality of the transmission channel measured right before it uploads its message. The end device can thereby adjust precisely the transmission speed (or SF in LoRa jargon) in order to make best use of the transmission channel capacity and save on battery power consumption.
By contrast, LoRaWAN end devices have to rely on past downlink messages to adjust SF. Anyone versed into RF communications knows that the transmission channel quality is highly unstable especially when the signal is weak. Therefore, LoRaWAN end devices have to resort to sending messages with a good margin in signal strength, like 6 or 9 dB, to stand a good chance for the message to go through. This corresponds to a margin of 3 SF grades which results in multiplying the transmission time by 8 and power consumption accordingly.
The situation is far worse for a mobile device that has potentially no idea about the quality of the transmission channel because it may have moved since it received its last downlink message from the gateway. Such a device has to resort to setting SF12, that is the longest transmission time lasting typically over 2 seconds whereas it may have been able to set SF8 for instance with a transmission time 32 times shorter. This is a major advantage of PicoWAN over LoRaWAN: reduced transmission time and power consumption.
PicoWAN MAC makes an optimum use of air time on the unique channel out of a pool of 32 channels open at a given time so as to avoid collisions through a good synchronization of packets uploaded from end-devices. As the uplink transmission is synchronized, potential collisions will most likely affect only current and not already ongoing transmissions. In other unsynchronized schemes like e.g. LoRaWAN collisions will occur also by overlapping transmissions severely limiting the achievable throughput (“ALOHA”). Monitoring the noise level, disturbed channels are detected and can be avoided. As a result, the maximum capacity of a PicoPlug exceeds 50k connections/day.
With PicoWAN, ACKs are automatic and free of charge: no restrictions in the number of ACKs sent, no double or triple charge for ACKs, no further restrictions on duty cycle in the ISM band.
Every uplink message is automatically acknowledged (ACK) immediately after sending. This allows for immediate detection of any message not reaching the gateway. The device can then repeat the message (automatic repeat request ARQ). So no messages are lost and there is no need to send blindly messages several times because no ACK is available.
LoRaWAN is very limited in providing for ACKs on uplink traffic, as the gateway cannot receive while transmitting in the same ISM band. To send an ACK, a gateway has to abandon incoming traffic on its many uplink channels and will miss all concomitant incoming messages to serve the one message received that requires acknowledging. It is understandable that this scheme does not scale and thus ACKs are usually severely restricted in LoRaWAN.
In general, downlink is a problem for systems like LoRaWAN due to restrictions on air time in ISM regulations (duty cycle limited to 1% or less). So sending ACKs eats up gateway’s precious air time. In addition ACKs are sent on normal data channels increasing the likelihood of collisions. By contrast, PicoWAN is organized in a fashion that does not require any additional air time for acknowledging.
The result is that although LoRaWAN supports message acknowledging, it is of limited use in practice as soon as traffic densifies. As for Sigfox, there is no reliable downlink with enough bandwidth to send ACKs to devices, so the protocol resorts to sending packets three times in a row wasting precious bandwidth and battery power.
PicoWAN MAC is organized in a fashion that allows for the co-existence of tens of PicoPlugs active in the same area without interfering, so that the number of gateways can be multiplied as needed to meet any network capacity requirements.
A PicoPlug is a full-fledged LoRa© gateway combined with a WiFi smart plug. PicoPlugs can be made at a very low-cost, actually as cheap as end-devices, with no infrastructure cost, and distributed virtually anywhere over a territory so as to meet any capacity requirements and reach any connected object even located very deep indoor:
PicoWAN is a very low-cost flat-fee network:
Although e.g. LoRaWAN or Sigfox allow for bi-directional communication, downlink from the network server to end-devices is severely limited by ISM regulations, typically to 1% of air time, which is extremely small to serve thousands end-devices from one gateway. Another even more severe limitation lies in the fact that depending on the implementation a downlink communication taking place from the gateway precludes any concomitant uplink. PicoWAN does not suffer from the same limitations considering that each PicoPlug serves fewer end-devices and the number of PicoPlugs can always be increased, almost at will, to reach the desired network capacity and deepest indoor coverage.
It is extremely important for any LPWAN to incorporate security. PicoWAN utilizes two standard layers of security, one for the network and one for the application, based on AES encryption and MIC (message integrity check).
Two keys are used: one is known to the network and is used for network management. The other key is owned by the customer (or a third party the customer is working with) and ensures the confidentiality of the data.