NB-Fi – the IoT Standard
NB-Fi is an LPWAN protocol that supports secure bidirectional communication for Internet of Things (IoT), machine-to-machine (M2M) and Industrial Internet of Things (IIoT) applications. NB-Fi makes it possible to realize the enormous potential of the Internet of Things by collecting and analyzing data from end devices for analytical, accounting, billing and ERP systems.
NB-Fi technology ensures wireless communication between devices in hard-to-reach places over long distances in dense urban areas, being perfectly fit for the building of IoT networks, deployment of automated metering systems for utilities, Smart Grid and Smart City projects, wireless solutions for industrial, agriculture, monitoring and alarm systems. NB-Fi is an open standard with disclosed format of NB-Fi messages and relevant technical data required for manufacturers to produce compatible IoT end devices.
NB-Fi technology overview
LPWAN technologies may be divided into two groups: Wideband and Narrowband systems. In Wideband systems, one channel typically occupies a frequency band with a width from 100 kHz to several MHz, while in Narrowband systems one channel has a bandwidth from 50-100 Hz.
Technologies of low-power narrowband radio communication began rapidly developing in the world on the back of the improvement of oscillators' accuracy, which allowed increasing the duration of signal stability: it became possible to narrow the transmission band preserving the signal power limits. Long duration of signal stability in Narrowband systems allows transmitting data at a low data rate at distances of 10 kilometers and more without exceeding the power limits in unlicensed bands (typically, from 25 to 100 mW). One of the advantages of Narrowband systems, such as NB-Fi (“Narrow Band Fidelity”), is the effective use of radio frequency spectrum. The width of one NB-Fi frequency channel starts from 50 Hz. NB-Fi devices use the 50 kHz bandwidth for Uplink messages and the 100 kHz bandwidth for Downlink messages, which are only small channels inside the allowed license-free ISM bandwidth. Thousands of NB-Fi channels can be accommodated simultaneously within these bandwidths. The narrowband signal and high energy per bit of transmitted information provide for an excellent energy potential for the link budget and a high noise immunity.
Key advantage of the highly sensitive NB-Fi base station is its ability to receive a signal with a low SNR – down to zero, i.e. when the signal level does not exceed the noise level. Base stations use advanced filters to provide an unrivaled level of dynamic range of a signal. NB-Fi base stations can process thousands of channels simultaneously, digitizing the entire bandwidth in real time and receiving the messages which were sent at different data rates.
Spectrum of the NB-Fi base station: receiving signals with different data rates (narrow bands – low data rates, wide bands – high data rates)
Specification of the NB-Fi protocol
NB-Fi standard supports bidirectional (Uplink and Downlink) communication. This is primarily required for end devices like electricity meters, where a Downlink channel allows controlling the meter: time synchronization, tariff schedule update, load relay switch off etc. NB-Fi transceivers built into end devices, together with sophisticated signal reception algorithms, ensure almost symmetrical communication channel in both directions.
NB-Fi standard for bidirectional communication supports the adaptive data rate. If the signal strength is good, devices will automatically switch to a higher data rate. This allows using the spectrum efficiently and reduces the consumption of power necessary for transmitting data. NB-Fi standard supports up to 4.3 billion devices in a single network with a 32-bit ID for each device. NB-Fi does not use IP addressing (IPv4, IPv6) in order to optimize the payload. IoT devices (such as sensors and gauges) can transmit tiny few-bytes data packages. The minimum size of an IP header is 20 bytes, thus the Non-IP Data Delivery (NIDD) approach allows developing simpler and cheaper devices. Data exchange between devices and third-party applications is possible via the NB-Fi server's API.
NB-Fi UPLINK overview
|Minimum reception bandwidth of the NB-Fi base station||51.2 KHz|
|Data rate||50, 400, 3200, 25600 bps|
|Packet length||288 bits|
|Multiple access method||Time & Frequency|
|Number of simultaneously received channels in 51.2 kHz bandwidth||1024 (at the data rate of 50 bps)
128 (at the data rate of 400 bps)
16 (at the data rate of 3200 bps)
1 (at the data rate of 25600 bps)
|Ultimate reception sensitivity||-150 dBm (for the data rate of 50 bps)
-141 dBm (for the data rate of 400 bps)
-132 dBm (for the data rate of 3200 bps)
-123 dBm (for the data rate of 25600 bps)
|UPLINK packet reception throughput of one NB-Fi base station||20 Mbit/day|
NB-Fi MAC and Transport Layers overview
|Network numbering capacity||4.3 billion devices (232)|
|Effective data rates
||12.5, 100, 800, 6400 bps|
|Encryption algorithm||AES-256 or other symmetric block cipher algorithm with 256-bit encryption key|
|Payload for one NB-Fi packet||8 bytes|
|Maximum payload length for a group packet at Transport layer||240 bytes|
NB-Fi vs. other LPWAN technologies
LPWAN systems are used to transmit data over long distances successfully, using both narrowband and broadband signals. Each of these systems has its pros and cons –the right technology should be chosen depending on technical requirements and other considerations.
NB-Fi technology is focused on energy efficiency and extra long battery life of devices, and is designed for solutions that require fast and inexpensive rollout of IoT networks with a 100% data collection rate from the devices. The comparison among NB-Fi and other LPWAN technologies is below.