NB-IoT is the future of low power for smart metering and monitoring over cellular networks. It fits into the LPWAN space by offering a technology able to handle large number of low power devices in a controlled and smart way on top of the existing 4G.

Introduction

During the recent years we have seen a technological race to meet the demand of the blooming IoT sector for longer battery life and cheaper network access.

This wireless network technology has a number of advantages compared to other LPWAN approaches like LoRa. It allows centralized network control, abilty of the base station to control when and how devices will transmit, sending relatively large packet sizes over kind of normal IP protocols like TCP and UDP.

Practical applications of NB-IoT

Any devices that require low energy consumption, have low data transfer demands and are geographically dispersed or remote can benefit from NB-IoT. That include:

  • Gas Metering
  • Environmental Monitoring
  • Water Metering
  • Smoke and Fire Alarms<F/li>
  • Liquid and pressurised fuels
  • Parking monitoring
  • Smart Bins
  • Low power level monitoring
  • Alarms and event detectors

NB-IoT bands

NB-IoT can exist either: 1) independently, 2) in unused 200-KHz bands that have previously been used for GSM, or 3) on LTE base stations that can be allocate a resource block to NB-IoT operations or in their guard bands.

Currently NB-IoT is known to work on the following frequency bands

B1/B2/B3/B4/B5/B8/B12/B13/B17/B18/B19/ B20/B25/B26*/B28/B66/B71/B85

You can read more on which band to which freqency corresponds here.

LTE-M – an LTE-based alternative to NB-IoT

LTE-M (also know as LTE Cat-M1 and LTE Cat-M2), however, is an attractive option for those mobile carriers looking to deploy purely current cellular networks. From the weak spots, LTE-M power efficiency may not be fully comparable to NB-IoT and chips may come with a bit higher cost. Also, NB-IoT can handle wider deployment coverages than LTE-M. Therefore, the adoption of either NB-IoT or LTE-M depends partly on mobile carrier’s preference. NB-IoT vs LTE-M difference in bandwidth

1) independently, 2) in unused 200-KHz bands that have previously been used for GSM, or 3) on LTE base stations that can be allocate a resource block to NB-IoT operations or in their guard bands. LTE-M (also know as LTE Cat-M1 and LTE Cat-M2) is an attractive option for those mobile carriers looking to deploy purely current cellular networks. From the weak spots, LTE-M power efficiency may not be fully comparable to NB-IoT and chips may come with a bit higher cost. NB-IoT can handle wider deployment coverages than LTE-M. Therefore, the adoption of either NB-IoT or LTE-M depends partly on mobile carrier’s preference. NB-IoT vs LTE-M difference in bandwidth

NB-IoT0.2 MHz
LTE-M1.4 MHz

Based on that obviously LTE-M has an advantage in the amount of data that could be transfered from/to a single device. Thus our expectation is that it will be more suitable for FOTA (Firmware over the air upgrades) and will be a prefered choice for application where that might be needed. In smart metering/monitoring the world has lived without that for many years so we don’t expect this to be a critical factor. Most of the world will stay on NB-IoT and only few network operators Verizon in the US will go to LTE-M.

What have we done to fit NB-IoT in ThingsLog product portfolio

Hardware modifications

Our early prediction that NB-IoT is the future of low power have resulted in the development  LPMDL-1102. The data logger has been based on the existing 2G data logger – LPMDL-1101 with few minor modifications. The batteries have changed, the number of transmissions have been increased from 5 to 10k+, ability data logger to work continiously for long period of time in low temperatures (continious work on -20 °C) has been achieved. 

Software changes

From software/firmware point of view the NB-IoT added a couple of extra and exciting new opportunities – easier implementation of protocol stacks like MQTT and LwM2M ability and additon of PSM and eDRX.

As a final result we have an extremely low power device able to work in very low temperature conditions useful for any kind of flow measurements (water, gas, power, oil). The technology is also suitable for pressure, level, temperature, humidity and other environment measurements. 

Power Saving Mode (PSM)

PSM is a device mode in which the unit can signal to the network that it will “sleep” for a while. Having that mode the device saves battery cycles from attaching/detaching from the network. The network itself also knows when and where (in which base station) to keep the device contex active.

Extended Discontinuous Reception (eDRX)

eDRX is a mode in which the device could still be alive and reachable but won’t send data. This is achieved by switch off its radio receive part of the data transmitter. Thus it saves some power, while remains still attached to the network. If the network want to send data ot the device it will receive it with small delay equal to a preconfigured eDRX timer.

Comparioson with other wireless technologies

Cellular networks are not that well optimised for applications that only transmit small amounts of infrequent data. The existing cellular standards don’t favor IoT hardware designers to invent low power devices. For example during paging a GSM M66 data module might reach up to 2 A of peak current. Even if GSM data modules support kind of a sleep mode they still require a good 100-200 mA in it. The only way to be low-power is by switched off the module during the periods of no transmission.

Free alternatives

The market have been working on new emerging wireless networks for years. People call those network technologies Low-Power WAN (LPWAN) or Low-Power LAN (LPLAN). We need LP-WAN in case of data transmissions over several hundred meters. Examples of LPWAN technologies include SigfoxLoRaWAN and Weightless-P. All of these infrastructures require independent radio network from the existing cellular network.

We need LPLAN technologies when short range transmissions are required. Smart home within the house is a great example. Examples for LPLAN technologies are Zigbee and Z-wave.

3GPP reaction

However, mobile carriers and 3GPP in particular also wanted to play part in the show. As a result of that NarrowBand IoT (NB-IoT) has been born.

NB-Iot fills the gap of cheaper network access combined with small amounts of data. It handles small but sufficient amounts of fairly infrequent 2‑way data, securely and reliably.

An NB-IoT module needs just 200 mA peak current during the network attachment phase. The module will consume couple of μA power in power sleep mode. The modules will work also need voltage between 2.1 and 3.8 V. That simply means devices suitable for a large number of Lithium batteries (2G will need typically 4.5V). Saying all that NB-IoT is the future of low power and is here to put its mark on the sector.

NB-IoT advantages

The technology’s main pros include:

  • very low power consumption (comparable with LoRa and Sigfox)
  • excellent penetration coverage
  • lower hardware costs

The big advantage of NB-IoT is that it will be a global standard. Carriers will not require the installation of new antennas. To deploy it they will have to perform software upgrade to existing cellular base stations.

NB-IoT is the future of low power for smart metering and monitoring over cellular networks.

For more information, please Contact us.

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