Lora Spread

Lora Spread

LoRa networks ¶

Gateways can handle 100s of devices at the same time.
The gateways can listen to multiple frequencies simultaneously, in every spreading factor at each frequency.
Communications are bidirectional

uplink : end node -> gateways
downlink : gateway -> end node
The LoRaWAN protocol does not support direct communication between end nodes. If you want direct communication between LoRa devices without the use of gateways, use the RadioHead Packet Radio library for embedded microprocessors. It provides a complete object-oriented library for sending and receiving packet sized messages via a variety of radios such as LoRa on a range of embedded microprocessors: https://www.airspayce.com/mikem/arduino/RadioHead

example : 80C02301260021000266EEA76CCE0C1BBC7A36F69F
80 C0230126 00 2100 02 66EEA76CCE0C1BBC 7A36F69F
MTYPE devaddr FCtrl FCnt FPort DATA MIC

from lora.crypto import loramac_decrypt

payload = '80C02301260021000266EEA76CCE0C1BBC7A36F69F'
sequence_counter = int ( payload [ 14 : 16 ] + payload [ 12 : 14 ], 16 )
app_session_key = '91299DA630B26526967B442361820CAD'
dev_addr = payload [ 8 : 10 ] + payload [ 6 : 8 ] + payload [ 4 : 6 ] + payload [ 2 : 4 ]
decrypted_payload = loramac_decrypt (
payload [ 18 : 34 ],
sequence_counter ,
app_session_key ,
dev_addr )
# Result : 0xbe 0xef 0xde 0xad 0xbe 0xef 0xde 0xad

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Documentation overview

©2018, Eric B.

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Source : https://youtu.be/cUhAyyzlv2o (whole playlist)
LPWAN stands for Low Power Wide Area Network and this type of wireless communication is designed for sending small data packages over long distances, operating on a battery
LoRa modulation / radio part -> closed sources
LoRa operates in the unlicensed ISM (Industrial, Scientific and Medical) radio band that are available worldwide.
A more detailed list of LoRa frequencies used per country can be found at:
In Europe the European Telecommunications Standards Institute (ETSI) creates standards which are used by local (= country) regulatory authorities.
In the US the Federal Communications Commission (FCC) creates these standards.
For example in Europe when using the ISM band frequencies (863 MHz - 870 MHz) users must comply to the following rules:
Besides these ISM band rules, the network operator (for example The Things Network) can also add additional restrictions.
If you use The Things Network (free public community LoRaWAN network), the following fair use policy applies:
When a signal is send from a sender it takes a certain amount of time before a receiver receives this signal. This time is called Time on Air (ToA) .
Duty cycle is the proportion of time during which a component, device, or system is operated. The duty cycle can be expressed as a ratio or as a percentage. As mentioned previously in Europe there is a 0.1% and 1.0% duty cycle per day depending on the channel.
For example : ToA = 530ms => affer sending a message, we have to wait 99x530ms = 52.47s before sending a new message.
The LoRaWAN specification defines three device classes:
At any time an end node can broadcast a signal. After this uplink transmission (tx) the end node will listen for a response from the gateway.
The end node opens two receive slots at t1 and t2 seconds after an uplink transmission. The gateway can respond within the first receive slot or the second receive slot, but not both. Class B and C devices must also support class A functionality.
Note : “All” means the class A mode is supported by all classes.
In addition to Class A receive slots, class B devices opens extra receive slots at scheduled times.
The end node receives a time synchronised beacon from the gateway, allowing the gateway to know when the node is listening. A class B device does not support device C functionality.
In addition to Class A receive slots a class C device will listen continuously for responses from the gateway. A class C device does not support device B functionality.
L(fs) = 32.45 + 20log(D) + 20log(f)
The Fresnel zone is an elliptical shaped body around the direct line of sight path between the end node and the gateway.
Any obstacle within this volume, for example buildings, trees, hilltops or ground can weaken the transmitted signal even if there is a direct line of sight between the end node and the gateway.
=> avoid objects within the Fresnel zone
As a rule of thumb Fresnel zone should always be clear of obstruction but this can be impractical so it is said that beyond 40% blockage, signal loss will become significant.
A link budget is the sum of all of the gains and losses from the transmitter, through the medium (aka free space), to the receiver in a telecommunication system. It is a way of quantifying the link performance.
The receiver sensitivity is the lowest power level at which receiver can receive or demodulate the signal.
The Effective Isotropic Radiated Power (EIRP) is the total power radiated by a hypothetical isotropic antenna in a single direction.
The Effective Radiated Power (ERP) is the total power radiated by an actual antenna relative to a half-wave dipole rather than a theoretical isotropic antenna.
EIRP = Tx power (dBm) + antenna gain (dBi) - cable loss (dBm)
For example: EIRP = 20 + 10 - 5 = 25 dBm
ERP = Tx power (dBm) + antenna gain (dBd) - cable loss (dBm)
For example: ERP = 20 + 7.85 - 5 = 22.85 dBm
Relationship EIRP and ERP: EIRP (dBm) = ERP (dBm) + 2.15
What is the purpose of ERP and EIRP?
RF transmitting systems must adhere to certain rules set by the regulatory bodies such as FCC or ETSI.
One of these rules: radio devices must not exceed certain ERP or EIRP values set by these regulatory bodies.
The Received Signal Strength Indication (RSSI) is the received signal power in milliwatts and is measured in dBm.
This value can be used as a measurement of how well a receiver can “hear” a signal from a sender.
The RSSI is measured in dBm and is a negative value.
The closer to 0 the better the signal is.
Signal-to-Noise Ratio (SNR) is the ratio between the received power signal and the noise floor power level.
The noise floor is an area of all unwanted interfering signal sources which can corrupt the transmitted signal and therefore re-transmissions will occur.
Normally the noise floor is the physical limit of sensitivity, however LoRa works below the noise level.
Typical LoRa SNR values are between: -20dB and +10dB
A value closer to +10dB means the received signal is less corrupted.
LoRa can demodulate signals which are -7.5 dB to -20 dB below the noise floor.
Regional LoRa Alliance parameters :
Downlink : same as uplink with an additional one :
If your country uses the EU863-870 ISM band, than according to the LoRaWAN Regional Parameters document every EU868MHz end device must implement the following default channels:
The other 5 frequencies can be freely attributed by the network operator. For example, The Things Network implemented the following frequencies: 867.1, 867.3, 867.5, 867.7 and 867.9.
LoRaWAN only uses the following bandwidth ranges: 125 kHz, 250 kHz and 500 kHz.
Which of these 3 ranges are actual used depends on the region or frequency plan.
For example in Europe only the bandwidths 125kHz and 250 kHz are used.
An end device changes channel in a pseudo-random fashion for every transmission.
Changing frequencies makes the system more robust to interferences.
For example in Europe for uplink transmissions 8 different frequencies are used.
Dwell time (or transmit time) is the amount of time needed to transmit on a frequency.
Hop time is the amount of time needed to change from one frequency to another in which the radio is not transmitting
To generate symbols/chirps, the modem modulates the phase of an oscillator. The number of times per second that the modem adjusts the phase is called the chip rate and defines the modulation bandwidth. Chip rate is a direct subdivision of the quartz frequency (32 MHz).
Basic chirps are simply a ramp from fmin to fmax (up-chirp) or fmax to fmin (down-chirp). Data-carrying chirps are chirps that are cyclically-shifted, and this cyclical shift carries the information.
Spreading Factor (SF) : defines the number of bits that can be encoded by a symbol.

2-5 km (urban)
5-15 km (rural)
> 15 km (LOS)

Principle of Lora frequency hopping spread spectrum communication Home All articles Product News|NiceRF
Copyright © 2020 NiceRF Wireless Technology Co., Ltd. NiceRF is focused on developing wireless module , RF transmitter and receiver module , LoRa module .
FHSS, frequency hopping spread spectrum(FHSS) technology, under the condition of synchronization and simultaneous,receives signals transmitted by specific types of narrow-band carriers at bothends. For a non-specific receiver, the hopping signal generated by FHSS is onlypulse noise.
When a single packet time may exceed themaximum channel dwell time allowed by relevant regulations, FHSS technologywill be used. To turn on the frequency hopping mode in Lora, you need to setthe reghopperiod and freqhoppingperiod registers to non-zero values.
The principle of FHSS frequency hoppingspread spectrum scheme is as follows: part of the contents of each Lora packetare transmitted through the frequency hopping channel set by MCU management,i.e. the required "hopping" frequency (according to the frequencyquery table). After the scheduled frequency hopping cycle is completed, thetransmitter and receiver switch to the next channel of the predefined list offrequency hopping so as to continue transmission And accept the next part ofthe package. The dwell time in any channel is determined by freqhoppingperiod,which is an integral multiple of the symbol length.
The process of transmitting and receivingby frequency hopping starts from channel 0.. So the preamble and header will besent in channel 0 first.. Each time a packet is sent, the reading of thechannel counter fhsspresentchannel (located in reghopchannel) will increase,and an interrupt signal fhsschangechannel will be generated to realizefrequency hopping. The new frequency must be set in the frequency hopping cycleto ensure that the new frequency will be covered in the next frequency hopping.
FHSS usually starts from channel 0. Afterchecking the preamble, the receiver will start the above frequency hoppingprocess. At this time, if the CRC of the header is not correct, the receiverwill automatically request channel 0 (packet retransmission mechanism) andrestart the check preamble.
After switching to the new frequency, fhsschangechannelinterrupt will be generated, that is, the interrupt of changing channel. Asshown in the figure below, the interrupt signal generated when the frequencyhopping is successful:
The ultra-low power sensor monitoring system is mainly used for sensor data acquisition and control of the Internet of Things.
In August 2022, NiceRF launched a new LLCC68 LoRa module: CC68-C1.
NiceRF: Demonstration of communication between LoRaWAN gateway and server.
RF4463Pro and RF4463F30 are both Si4463 RF modules launched by NiceRF. The following are the commonalities and differences between these two RF modules.
At present, low-power Bluetooth technology has been widely used. It can run for a long time with only one button battery. So how to choose a BLE module?

© Copyright Link Labs, 2022. All Rights Reserved. Privacy Policy

“What is LoRa?” Whenever someone asks me this question, it’s hard to know exactly how to answer without knowing why they’re asking. That’s because LoRa can refer to more than one thing:
LoRa, essentially, is a clever way to get very good receiver sensitivity and low bit error rate (BER) from inexpensive chips. That means low-data rate applications can get much longer range using LoRa rather than using other comparably priced radio technologies.
But LoRaWAN is different. It is a media access control (MAC)-layer protocol built on top of LoRa, built using Semtech’s LoRa modulation scheme. LoRaWAN, however, is rarely used for industrial (private network) applications. It is a better fit for public wide-area networks because all the channels are tuned to the same frequencies; for single-area use, it’s better to have only one network operating in order to avoid collision problems.
Because all the gateways in a network are tied back to the same server, it’s the server’s job to decide which gateway should respond to a transmission. In a large network, any given transmission is typically heard by multiple receivers; the server then tells one gateway to respond and the others to ignore the transmission. This process helps avoid downlink and uplink collisions , because a single gateway is transmitting, and the gateways that are overlapping can simply listen for other transmissions. (You can read more about LoRaWAN here.)
What many people don’t realize is that there is a way to use the underlying technology of LoRaWAN—which is LoRa— without using LoRaWAN. Link Labs’ Symphony Link , for example, uses a proprietary MAC layer on top of Semtech’s chips, and has additional features that make it a better fit for enterprises and industrial customers who need a way to securely connect their IoT devices to the cloud. There are plenty of companies out there using LoRa chips for other protocols; all you have to do is seek them out.
From a technical standpoint, LoRa is a unique (and awesome) modulation format. This video is the best LoRa intro I have found. ( Caveat: It is very technical.)
Generated by Semtech LoRa IOT parts , including the SX1272 and SX1276 transceiver chips, LoRa’s modulation format is best described as a “frequency modulated (FM) chirp.” The core IP that enables LoRa is the ability to generate a stable chirp using a frac-N phase lock loop (PLL). Here can read the core LoRa patent. Other modulation formats include frequency shift keying (FSK), phase shift keying (PSK), etc. It is important to remember when asking “What is LoRa?” that LoRa itself does not describe system functionality above the physical (RF medium) layer.
Semtech acquired the LoRa wireless technology through its acquisition of Cycleo SAS of Grenoble, France for $5M in 2012. A bargain!
When processing a LoRa message, additional processing gain is achieved due to the modem’s ability to filter on the constant ramp chirp signal. This is how high sensitivity is achieved. In order to achieve “lock” to the LoRa signal, a long “constant chirp” preamble is transmitted. (See Figure 1.) This is really the power of LoRa—that an inexpensive chip with a cheap crystal can achieve very high sensitivity.
This preamble can be set as a variable number of “symbols,” which are just the number of chirps. As you might imagine, there is no selectivity between a preamble from one LoRa transmitter vs. another. If there is a constant chirp at the right frequency and at the right chirp rate, a LoRa demodulator will listen to it, whether its from the intended system or not. Managing a LoRa receiver system to be agile in the face of regular power interference and LoRa interference is very important, and is a key part of Symphony Link.
Once a LoRa modem has “locked” on to the preamble signal, the end of the preamble is signaled by the “reverse chirp” seen in Figure 1.
Then the data transmission begins, which has a series of “symbols” that function much like M-ARY FSK symbols, but instead happen on a chirp. See Figure 2.
Another powerful feature of LoRa is the ability to demodulate several “orthogonal” or simultaneous signals at the same frequency, assuming they have different chirp rates. In the datasheet, LoRa chirp rates are called “spreading factors,” with higher spreading factors denoting slower chirps. This function is supported by the SX1301 chip from Semtech. All Link Labs gateway systems have the ability to decode many simultaneous LoRa chirps simultaneously, which allows very large networks to be built.
Building such a LoRa network or system requires a tremendous amount of development. Going from LoRa to a functioning wireless system is analogous to going from having a BPSK radio chip to having a WiFi network. The OSI layer 2 and above functions of large networks that include gateways, repeaters, addressing, adaptive data rates, message retries, message acknowledgments, and high capacity OFDM downlink signals are the function of systems like LoRaWAN and Symphony Link.
There has been a movement to standardize the MAC features for LoRa called the LoRa Alliance , of which Link Labs was an early member. The LoRa Alliance developed the LoRaWAN protocol for use by mobile network operators who want to use unlicensed spectrum to communicate with IoT devices in their network.
In contrast, Symphony Link is a standardized protocol developed by Link Labs and our customers who love the range of LoRa, but need a level of performance that is not available with LoRaWAN. It is specifically focused on ITU region 2 (915 MHz ISM Band). LoRaWAN is ideally suited for ITU region 1, where ETSI transmitter duty cycles restrictions greatly limit the role the base station can play in the network.
Some details on LoRaWAN, the LoRa Alliance protocol for LoRa:
Some companies are using the full LoRa/LoRaWAN technology stack in interesting ways such as outdoor asset tracking . For example, Ofo a Chinese bike-sharing company is equipping its bicycles with LoRa devices and wireless radio frequency technology to pinpoint the bikes’ locations. The company currently operates in more than 180 cities in China.
Another example of LoRa network utilization comes from the Santa Rosa, California, based company PNI Sensor. PNI uses LoRaWAN-based wireless connectivity to deliver real-time city parking data , making it easier for drivers to find available parking spaces for on-street and off-street public and private parking management. The end goal is to reduce traffic congestion and carbon emissions caused by drivers retracing their steps repeatedly in an effort to find available parking.
A number of industries are leveraging the open LoRaWAN standard for IoT devices, including agriculture (for irrigation/water level monitoring and pest control), utilities (for smart electric meters, lighting, and energy management scenarios), and building construction (for building door and window sensors and building structural health applications).
There are also plenty of companies doing LoRa-based networks that aren’t LoRaWAN.
LoRaWAN is a great choice for protocol if you want to build on carrier-owned-and-operated public networks. There are many hardware and network server providers competing in this space, so there is a lot of choice—which is a great benefit. But the process of developing and deploying a system around LoRaWAN is quite complex, and it will be challenging if you don’t have much expertise or experience with radio frequency protocols or wireless systems and planning. You’ll also need to think through if deploying a LoRaWAN™ network will meet your needs. In some cases, it could be better to use a custom protocol, where all you have to do is send data to a node that’s already written to connect to the cloud. If you use Symphony Link , for example, we have already done this work for you.
Whatever network is right for your application , development kits make testing and prototyping easier. Here are some dev kits I recommend for getting started with whatever technology you choose:
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