LoRa or Cellular for IoT: Which is the Right Choice for You?

Paul Marshall

Founder & CCO

LinkedIn

The enormous potential of IoT is matched by the enormous complexity of achieving ROI with IoT deployments. From designing secure, resilient devices to creating applications that derive real value from the device data, there are many choices and compromises along the journey to a successful deployment.

One of the major choices is connectivity. There’s a wide variety of options, with differing levels of adoption and availability, energy efficiency, cost, quality of service and security. It’s not surprising companies find it hard to find the right connectivity technology – but the wrong choice can wreck a business case. For example, ROI can be wiped out if batteries in remote devices don’t last as long as expected, or the chosen network doesn’t support the real-time communication required for mission-critical applications.

Two prime connectivity contenders for IoT are cellular networks and LoRaWAN®. This article compares and contrasts these technologies and provides some pointers for deciding which one best suits your IoT requirements.

Jump ahead:

• Challenges of Low-Power Wide-Area (LPWA) IoT applications
• What is LoRaWAN?
• What are the Cellular connectivity options?
• LoRaWAN vs Cellular connectivity comparison
• Cost comparison
• Futureproofing your IoT project
• Conclusion

Challenges of Low-Power Wide-Area (LPWA) IoT applications

Of all the billions of IoT devices in the world (estimated to reach nearly 31 billion in 20251), many billions will be simple devices sending small amounts of data at infrequent intervals. Examples include sensors recording temperature, humidity, and soil conditions, or reporting a status, such as whether a switch is on or off, or if a parking space is occupied or vacant.

Many of these devices are located in remote or inhospitable locations, such as oil rigs, farmland, underground, or basements. They usually have one or both of these characteristics:

• Battery-powered: batteries are used to keep the device size and cost to a minimum. Often there’s no reliable, accessible power source in the locations where devices operate and even if there is, it would be impractical to install cabling for all the devices in a deployment.
• Long range, high penetration connectivity: devices may need to communicate across long distances or through a difficult environment (such as underground), often in areas where there may be little or no telecommunications infrastructure.

For Low-Power Wide-Area (LPWA) devices, mobility and location have particular challenges:

• Moving IoT devices, such as those used for asset tracking, switch from one network cell to another as they move. This has an impact on the connectivity requirements and power consumption during handovers. If the device moves internationally, network availability and roaming in all regions must be considered.
• Devices are often installed across large areas in challenging conditions for a strong radio signal. Devices may be underground, deep within buildings, or in rural areas far from the nearest mast. Connectivity technology needs to deliver coverage for all devices and enable them to communicate efficiently.

Connectivity technologies that can meet the needs of these LPWA IoT devices and applications are of particular interest to many companies.

What is LoRaWAN?

The LoRaWAN specification is a LPWA networking protocol. As it’s an open specification, anyone can implement the protocol themselves on their own equipment. The protocol uses the proprietary LoRa radio modulation technology, which is owned by Semtech.

LoRaWAN operates in the unlicensed ISM (industrial, scientific, and medical) band, over a range of approximately 5-10km, and needs line of sight between devices and gateways. Its main purpose is for battery-operated devices to send small amounts of data at infrequent intervals to the internet.

LoRaWAN is supported by the LoRa Alliance, an open, non-profit association with more than 500 members. It has a large ecosystem of developers producing LoRaWAN-based hardware and software. However, semiconductors are only available from Semtech or its licensees.

How does LoRaWAN work?

Devices broadcast data via radio waves to a nearby LoRaWAN gateway. The gateway forwards the data to an internet server, which relays the data to an application in the cloud or a data centre.

LoRaWAN networks can simplify IoT setups, as it’s easier to install a few gateways in a contained area rather than installing many Wi-Fi routers or fitting SIM cards in all devices.

LoRaWAN Operating Modes

LoRaWAN networks are available in three forms: public, private and community.

According to the LoRa Alliance, there are LoRaWAN networks in over 160 countries, mostly local installations.

What are the Cellular IoT connectivity options?

Cellular networks are based on open, global industry standards, use licensed spectrum, and are always operated by wireless network providers. As well as the well-known 2G, 3G, 4G and 5G cellular standards, the GSMA has introduced two additional LTE standards, NB-IoT and LTE-M. These are primarily designed for LPWA use cases but are still in the initial stages of rollout.

GSM (2G, 3G)

GSM is the second-generation mobile telephone system and includes 2G and 3G. Primarily designed for voice, the standards also support SMS and GPRS data. They are proven, widely adopted standards, with hardware available at low cost.

Many mobile operators are in the process of shutting down 2G and 3G networks in favour of newer technologies. Before choosing a 2G or 3G service, it’s essential to make sure the service is available for the timespan and locations required.

LTE (4G, 5G)

LTE is the 4th generation mobile network system. Introduced in 2012, 4G is primarily designed for better scalability and wireless broadband. Although it’s not as wide range as GSM, it provides much higher data rates – comparable with Wi-Fi.

The latest standard is 5G. With bandwidths of up to 1 Gbps, 5G enables high speed communication with high capacities and very low latency. It can be used in mission critical applications, such as autonomous vehicles, as well as applications such as VR, AR, gaming, and any use cases requiring a real-time response.

The parallel operation of 4G and 5G promises greater capacity and faster network speeds in the future.

NB-IoT

Designed specifically for IoT devices, NB-IoT has the following characteristics:

• Uses a variety of frequency bands in unused GSM channels or the free space between LTE channels
• Is a self-contained carrier and only requires a bandwidth of 200 kHz
• Improves coverage over GSM by 20dB
• Supports battery life of 12–15 years
• Has a range of 10-15km
• Is compatible with existing cellular network infrastructure and has the same level of security as LTE, giving it significant advantages for IoT deployments

NB-IoT doesn’t support seamless handover when switching to another cell network tower. It can switch cells but must re-establish the connection, which takes more power. It’s possible to connect around 100k devices to one network cell tower, making it ideal for use in areas with high device densities and network usage.

Two power-saving capabilities, Extended Discontinuous Reception (eDRX) and Power Saving Mode (PSM), can maximise the performance and efficiency of devices connecting to NB-IoT networks. These features enable devices to sleep for long periods and minimise receiver activations, reducing the power usage associated with normal cellular connectivity.

LTE-M

LTE-M, also known as LTE Cat-M, is an extension to the LTE networks. Like NB-IoT, it offers a low speed, low power, long-range protocol for small bandwidth applications. Although it doesn’t provide the same length of battery life as NB-IoT, it offers a higher bandwidth, so is a good candidate for the use cases with higher volumes of data.

LTE-M is run on top of LTE base stations, making implementation more attractive for network operators as no dedicated hardware is needed. LTE-M can operate over a range of approximately 10-15km.

The power-saving capabilities, eDRX and PSM, can also be used with devices that connect to LTE-M networks.

LoRaWAN vs Cellular connectivity comparison

In this section:

• Limitations of LoRaWAN and Cellular networks
• Advantages of Cellular connectivity over LoRaWAN
• IoT Security

Limitations of LoRaWAN and Cellular networks

Different frequency bands

Different regions use different frequency bands:

• Europe: 865-868 MHz
• USA: 902-928 MHz
• Asia: 923 MHz

Ensuring that devices will operate wherever they’re located adds considerable complexity to designing and manufacturing LoRa devices.

Duty Cycles

Throughput is limited by national regulations to prevent network overload.

Regions impose power limits and duty cycles on the unlicensed spectrum. These differ between regions, again creating constraints on product design.

What is the duty cycle? The percentage of time that a channel may be actively occupied on the network. Unlicensed spectrum bands have severe legal restrictions on duty cycle. In Europe, the duty cycle restriction is 1%, which translates to a device having a maximum of 36 seconds every hour for transmission.

In the US, devices can’t be on air for longer than 400 milliseconds if the signal bandwidth is lower than 500 kHz. Devices might need to use frequency hopping to transmit their data successfully.

Duty cycle restriction may not be a problem during normal usage, where a device is only expected to transmit a daily status update payload of a few bytes but may be a real limiting factor during periods of high activity, when interference demands that a high percentage of packets are retransmitted, or in exceptional circumstances, such as pushing a new firmware version to a device over the air to secure a vulnerability.

Data loss

LoRaWAN networks can suffer performance degradation from packet collisions and interference if there are networks operating in the same area or in high density device deployments. If the number of devices connected to a network is larger than the shared number of channels, increased collisions and packet loss is likely. In addition, other services, such as wireless alarm systems and remote controls, can operate in these bands, adding to the congestion.

Data loss means devices must re-transmit or reduce their payloads. Re-transmitting data uses more power, impacting battery life, while reducing payloads may be a problem for some use cases. This type of network issue can produce disappointing results, particularly if it wasn’t anticipated at the time of deployment, for example, if device density wasn’t an issue at that time.

With no restrictions on setting up LoRaWAN networks or adding devices, packet collisions and interference are likely to increase. Data loss can start to become an issue when more than just a few hundred devices are communicating, which can be a significant problem if deployments need to scale to potentially millions of devices, or if other devices are deployed nearby.

Coverage and Roaming

Setting up new network infrastructure, such as gateways, masts, and repeaters, can be costly and slow, with challenges around planning permission, backhaul provisioning and other complicated issues, particularly in dense urban areas.

The challenges in creating reliable contractual frameworks between different network operators means there’s very limited roaming between networks. Roaming between different types of network can create reliability and security risks. It may be technically different because of the different frequency bands and regulations in different regions.

Advantages of Cellular connectivity over LoRaWAN

Cellular networks provide high quality services.

However, there are choices and compromises that have to be made. All cellular networks offer higher bandwidths, lower latency, higher reliability, and better coverage compared to LoRaWAN. However, not all cellular networks are suitable for LPWA applications.

When to choose Cellular connectivity

Making the right choice depends primarily on the use case requirements:

• LTE 4G and 5G are best for use cases requiring high bandwidth, low latency, and high levels of security. 5G in particular is suitable for mission critical applications.
• GSM 2G and 3G provide lower cost and lower energy consumption options than LTE, so are an option for simple devices requiring a battery life of a few years. They are subject to network shutdowns in some regions, so may not be suitable for long-term requirements.
• NB-IoT supports low energy, high penetration use cases, such as underground sensors.
• LTE-M doesn’t provide as good energy efficiency as NB-IoT but supports higher bandwidth and lower latency requirements.

Advantages of Cellular connectivity

Cellular connectivity has some significant advantages over LoRaWAN:

• Extensive network infrastructure worldwide is available to subscribers without requiring any investment or technical expertise to use.
• Coverage is comprehensive in many regions, with extensive roaming agreements between operators to support mobility. Note: NB-IoT and LTE-M are still in the early stages of rollout, so don’t have the same level of roaming arrangements as the other standards. NB-IoT does not support seamless handover when switching to another cell network tower.
• Device modules can support different RAT (Radio Access Technology) options, enabling them to switch between different networks if required to maintain optimum connectivity. For example, during NB-IoT and LTE-M rollouts, devices could operate on 2G or 3G. Or a device could switch from NB-IoT to a faster network to receive large firmware updates, saving battery life. Learn how to make eUICC-enabled battery-powered IoT devices.
• As fully open, global standards, cellular standards are subject to more intense scrutiny and continual improvement.
• There are no limits on the volume of data devices can send, other than contractually agreed maximums.
• Reliability is high with very low data loss even over long distances.

IoT Security

For most enterprises adopting IoT, security is a top concern. Vulnerabilities in poorly secured devices or networks can lead to hackers stealing data, disrupting services, or even taking control of remote assets.

It might seem that simple IoT devices, such as sensors, don’t need much protection. However, these devices can be recruited into vast botnets to use in DDoS (Distributed Denial of Service) attacks. Or malicious attackers could tamper with sensors to contaminate facilities such as water treatment plants or farmland, potentially causing a danger to life.

Security is a particularly difficult problem for LPWA devices, as constraints on bandwidth, physical size, and cost can make it challenging to implement robust security mechanisms such as authentication, encryption, and patching.

Key points for cellular connectivity:

• Cellular networks have well-proven security features, including strong authentication, industrial-grade cryptographic algorithms, data encryption over the air and secure key management. · SIM cards are highly secure, and devices with embedded or integrated SIMs are tamper-proof.
• Additional security provisions need to be implemented at gateways and for transmission over the internet, for example, by using private APNs and VPNs.

Key points for LoRaWAN:

• LoRaWAN uses two layers of 128-bit encryption to secure data sent from devices. One encryption key authenticates the device against the network server and the other against the backend application.
• LoRaWAN is considered secure by default, but it has been proved that version 1.0 of the protocol is susceptible to hacking and cyber-attacks if the devices and network are not designed and configured correctly.
• Version 1.1 has eliminated a number of vulnerabilities and security gaps, but this version is not yet in common use.
• The cybersecurity vulnerabilities aren’t well known, and there’s a lack of tools for testing the networks and detecting attacks.
• Anyone can transmit on ISM bands, making it easier for hackers to jam legitimate data transmissions.

Cost comparison

Cost is a critical factor in determining the viability of IoT use cases. LPWA module costs are likely to decrease as production volumes increase while network and connectivity costs depend on the type of network that is used.

LoRaWAN network costs

• Public network – the cost of subscription but no capital or operational expenses.
• Private network – capital and operational expenses for investment in infrastructure, such as gateways and network servers, as well as running, maintenance, and support costs. Companies can take on these responsibilities or subscribe to companies that provide them as services.
• Community network – none or small subscription cost but subscribers may have to provide gateways if there’s no coverage in their area.

Cellular network costs

• Subscription costs depend on factors such as the network type, bandwidth, and roaming requirements.
• Subscribers don’t have any capital or operational expenses for the infrastructure or operation of the networks.
• In general, the costs of connectivity and data are falling, changing the cost model compared to subscription-free networks.

_{All costs shown are approximate and correct as of July 2021}

Futureproofing your IoT project

IoT deployments often have a planned lifetime of ten years or more. It’s critical to consider whether all the factors in a deployment can withstand the test of time of the required lifetime.

Key questions to ask when deciding on IoT connectivity:

1. Will the networks have sufficient national and international coverage to scale up the deployment when required?
2. Will the network operate over the lifetime of the deployment? Are there likely to be any future regulatory restrictions that require devices to be modified or replaced?
3. Will there be enough market competition to ensure high quality while driving down the costs of hardware and connectivity? Is there a risk of becoming dependent on a single vendor?
4. Will suppliers continually enhance their technology, regularly improving performance and fixing security threats?
5. Will the available bandwidth support potential developments and evolutions that might require more data to be transmitted between devices and applications?
6. Is there an active community to support application development and troubleshooting?

Conclusion

With IoT, there’s no one size that fits all.

For many enterprises, the most important requirements for IoT network connectivity are coverage and quality. Given the issues with public and open LoRaWAN networks, the only currently viable option for LoRaWAN is to use a private network.

The different cellular standards serve a whole range of use cases. If the focus is on LPWA, the most viable, futureproof options are NB-IoT and LTE-M. However, the rollout of these networks is still in its early stages, with patchy coverage in many regions.

The table below summarises the main factors to consider when making an LPWA network connectivity choice.

Paul Marshall

Founder & CCO

LinkedIn

Paul is one of Eseye’s co-founders. With a background in senior design engineering, Paul’s focus is on ensuring his development, operations and support teams deliver solutions that work faultlessly in the field.

Paul was co-founder of CompXs, with Ian Marsden, and developed the world’s first IEEE 802.15.4 radio. Before CompXs, Paul was in senior radio design at Philips.