Frequently Asked Questions
The LoRa modem is capable of co-channel GMSK rejection of up to 19.5 dB or stated differently, it can receive signals 19.5dB below an interfering signal or the noise floor. This immunity to interference permits the simple coexistence of LoRa modulated systems either in bands of heavy spectral usage or in hybrid communication networks that use LoRa to extend range when legacy modulation schemes fail.
The term gateway and concentrator are both used, but they are equivalent components in a LoRa system. In other industries, the definition of gateway and concentrator imply different components.
LoRaWAN data rates range for LoRa between 0.3kbps to 11kbps and one GFSK data rate at 50kbps for Europe.
In North America, the minimum data rate is 0.9kbps due to FCC limitations.
To maximize both battery life of the end-devices and overall network capacity, the LoRaWAN network server is managing the data rate and RF output for each end-device individually by means of an adaptive data rate (ADR) algorithm.
The ADR is critical for a high performance network, and it enables scalability.
A network can be deployed with a minimal investment in infrastructure and as capacity is needed, more gateways can be deployed and the ADR will shift the data rates higher, which will scale the network capacity by 6-8x.
On the Tx side, the node or broadcast address must be set manually in the payload.On the Rx side, you can use a register to automatically perform the filtering on the nodes or broadcast address.
The SX1272 is integrated with two power amplifiers. One power amplifier is capable of delivering +20 dBm out of PA_BOOST, and the other power amplifier is capable of delivering +14 dBm out of RFO. If you wish to reach output power beyond +20 dBm, an external power amplifier will have to be added, preferably through RFO.
With all international networks, total uniqueness in the identity of the devices connected is a key requirement. Device EUI should be assigned from the IEEE unique database.
Semtech will provide details to the licensee about how data is protected and anonymised. All legal and local requirements will be taken into account in the detailed procedure defined.
Semtech and the licensee will define this to be compliant with all legal and local requirements
LoRa and NB IoT are both LPWAN technologies whereas 3GPP drives the NB IoT for carrier deployments in licensed band and LoRaWAN is an open standard driven by the LoRa Alliance.As there are material differences between the technologies the addressable markets and use cases are not the same. Overall the vision of the LoRa Alliance is that both technologies are complementary and based on the specific needs of a customer one is better off with either of the options.You can download the public whitepaper: “https://semtech.my.salesforce.com/sfc/p/E0000000JelG/a/E000000056Bf/JeMjZwyUqibxkZMhnf.GLiQmuM1uJnowBfso0MKTfD0” target=“_blank”>here.
Does the Semtech solution have to be integrated or can it be compiled as a stand-alone entity, can it be run as a service on a virtual machine?
The solution is provided as source code with full documentation. The system can be broken up into a number of different types of solution. It is easy to create virtual machine instances as well as fully integrating the core of the solution.
The files are provided in ‘C’ and ‘C++’ and are expected to be highly portable. The Semtech software support team is on-hand to enable smooth integration of the source code by any licensee.
The solution is provided as a complete end to end solution from gateway firmware to network service and controller through to website. The solution is provided to licensees in plain source code including all elements required to provide an end to end solution.
Semtech and the licensee will come to an agreement about how exactly this information is provided. A secure and electronic process will be defined.
The license is free of charge for the 2nd generation"location enabled” gateway, as are the 1st generation gateway reference designs.
In order to get as close to NLOS as possible it is important to observe the rules of propagation and try to get enough height in the gateway antenna to avoid the first Fresnel zone as much as possible. The mathematics defining the Fresnel zone are beyond the scope of this FAQ, however, as guidance, for an ISD of 4km, the antenna height should be 16m above the ground (and trees). With enough antenna height and an open landscape performance in the region of 10-30m have been observed.
With the early trial data, Semtech is recommending a 1.5km ISD in most urban cases as a guideline. There is, however, no substitute for detailed network planning and the coverage target should be four gateways. Targeting a configuration giving a four gateway redundancy means that in most cases, the sensor will be in coverage of all four, and in almost all cases will have the required minimum of three.
In the Class B principle, the latency is not defined by the number of nodes, but by the latency that the node requests to the network. If it negotiates 32 seconds with the network, then on average, it will be listening to the network every 32 seconds. When the load increases for Class B on a specific gateway, the impact is not delay but potentially overhearing of more than 1 device on a defined “meeting point”, in other words if the gateway is out of time slots, it may assign the same time slot to multiple devices. This would cause these devices to lengthen their listening time (and therefore consume more energy), even when the “other” device is interrogated. This impact is mild obviously, on the basis that network actuation is meant to be scarce (a few times per day typically).
If the end-device did not receive the downlink frame during the first receive window “RX1”, it must open a second receive window “RX2”. Note that the end-device does not open the second receive window if a frame intended for this end-device has correctly checked the address and MIC (message integrity code) during the first receive window.