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Wi-Fi & LoRaWAN deployment synergies

Wi-Fi and LoRaWAN® are two of the most-adopted unlicensed technologies and together they address a large percentage of IoT use cases. The approaches for these technologies are disrupting private-public business models and also enabling participation in 5G rollouts.

The Wi-Fi and LoRaWAN technologies are complimentary in nature, and network operators who have deployed either Wi-Fi or LoRaWAN may consider to extend their offerings by deploying the other technology. Wi-Fi is the unprecedented leader in broadband connectivity and LoRaWAN is the leader in long-range, low power connectivity.An existing operator who has deployed both technologies may future leverage their capabilities to support new use cases.

With over 20 years of history and advancements, Wi-Fi has become the world’s most common radio network for consumers and IoT. For example, today most MNOs around the world rely upon Wi-Fi networks to offload data generated by devices (voice, internet) located in buildings or in dense urban environments such as malls or venues. In 2018, Wi-Fi carried 67% of all mobile traffic in the US and 83% in Japan. Likewise, LoRaWAN has enjoyed similar rapid success. In just 3 years LoRaWAN has been adopted by more than 100 network operators, including leading MNOs such as Objenious, Orange, Proximus, KPN, NTT Docomo, SKT, KDDI, Swisscom and Tata Communications.

The combination of these unlicensed technologies allows covering the large majority and diversity of most IoT use cases, rolled out by any type of market actor. Today Wi-Fi is most often deployed to support critical IoT use cases whereas LoRaWAN is utilized for massive IoT use cases. When used in tandem, the two technologies support a vast array of IoT use cases in the following verticals, smart building/smart hospitality, smart cities/smart villages, smart venues, smart automotive and transportation, and In-home consumer.
An existing Wi-Fi infrastructure can be easily leveraged to deploy LoRaWAN as plug-in on Access Points (APs) or in Customer Premise Equipment. The level of integration (colocation or equipment convergence) will depend on coverage needs, sensor density and business requirements like SLAs.

Wi-Fi and LoRaWAN are widely implemented globally in real use cases supported by a strong ecosystem, while also being strongly synergistic. Examples of these use cases include:
Equipment suppliers working on mutualized software and hardware solutions (e.g.: Multi-Tech[38], Gemtek, Ufi, or Ruckus have combined Wi-Fi / LoRaWAN access points).
IoT device makers offering embedded Wi-Fi & LoRaWAN combined solutions, such as multitechnology trackers like Abeeway, OFO, Maxtrack, Chipsafer, and Gemtek.
Cities or public bodies moving to IoT: ER-Telecom in Russia deploying citywide Wi-Fi and LoRaWAN in top 60 cities [4] or city of Calgary who has complemented its Wi-Fi network with a LoRaWAN infrastructure.

MNOs driving a harmonized licensed and unlicensed strategy such as Orange [5] and BT [6].

Unlicensed operators focusing on LoRaWAN IoT strategy like Unitymedia [7] in Germany, and Tata Communications in India, Charter and Comcast in the US.

Roaming/Interconnection leaders driving a harmonized strategy to interconnect multiple IoT Connectivity technologies such as Orange, Syniverse, or BSG.

It is expected that simultaneous deployments of Wi-Fi and LoRaWAN to support IoT will have long term benefits. Both technologies have a strong history of market success, long term roadmaps and have a clear direction to support the future 5G world.

Technology explained
LoRa is a Chirp Spread Spectrum (CSS) physical layer supported by major silicon providers such as Semtech, ST Micro Electronics, Microchip and module makers such as Murata, IMST and many others. LoRa is an abbreviation of Long Range.

LoRaWAN defines the media access (MAC) protocol (open networking protocol) and the system architecture for a wide area network. The LoRaWAN specification is driven by the LoRa Alliance whose members (500+) are responsible for making and maintaining the MAC specifications on top of the LoRa physical layer.

LoRa. The term LoRa (Long Range) refers to the extreme long distance which can be achieved with very little power using a dedicated physical layer (PHY) based on CSS modulation. Transmission takes place in the license-free sub-gig ISM bands. Given the ultra-low power consumption measured in micro amps, LoRa is a preferred choice for battery operated sensors, which only require small data packets to be sent, or received. By using very low and adaptable bit rates (ADR), the sensor batteries will last for many years depending on transmission frequency. Given the range of a LoRa enabled gateway, enabling data transfer over long distances, the derived benefit is very low Capital Expenditure (CaPex) and Operational Expenditure (OpEx) when deploying a LoRaWAN network. Long range is achievable thanks to a correlation mechanism based on band spreading methods. This mechanism allows even extremely small signals disappearing in the noise, to be successfully de-modulated by the receiver. LoRa receivers are still able to decode signals, which are up to 19.5 dB below the noise.

LoRa signals have unique strengths, highly Robust, multipath/fading resistant, long Range Capability, Doppler Resistant, Enhanced Network Capacity, and Ranging/Localization.

A typical high-level system overview is built up of end nodes (sensors), gateways, a network server and an application server.

The LoRaWAN specification is a Low Power, Wide Area networking protocol designed to wirelessly connect battery operated things to the Internet in campus, regional, national or global networks, and targets key IoT requirements such as bidirectional communication, end-to-end security, mobility and localization services.

The LoRaWAN network architecture is deployed in a star-of-stars topology in which gateways relay messages between end-devices and a central network server. Gateways are connected to the network server via standard IP connections and act as a transparent bridge, simply converting RF (radio frequency) packets to IP packets and vice versa. The wireless communication takes advantage of the long-range characteristics of the LoRa physical layer, allowing a single-hop link between the end device and one or many gateways. All modes are capable of bidirectional communication, and there is support for multicast addressing groups to make efficient use of spectrum during tasks such as Firmware Over-The-Air (FOTA) upgrades or other mass distribution messages. The capability to receive the same message by multiple gateways increases the network SLA and prevents to manage hand-over between networks cells.

The specification defines the device-to-infrastructure (LoRa) physical layer parameters & LoRaWAN protocol and thus provides seamless interoperability between manufacturers, as demonstrated via the device certification program. While the specification defines the technical implementation, it does not define any commercial model or type of deployment (public, shared, private, enterprise) and thus offers the industry the freedom to innovate and differentiate to create competitive advantages.

LoRaWAN has three different classes of end-point devices to address the different needs reflected in the wide range of applications:

Class A – Low power, bidirectional end-devices
The default class, which must be supported by all LoRaWAN® end-devices, class A communication is always initiated by the end-device and is fully asynchronous. Each uplink transmission can be sent at any time and is followed by two short downlink windows, giving the opportunity for bidirectional communication, or network control commands if needed, a so-called ALOHA type of protocol. The end-device is able to enter low-power sleep mode for as long as defined by its own application: there is no network requirement for periodic wake-ups which makes class A the lowest power operating mode. Downlink communication must always follow an uplink transmission with a schedule defined by the end device application; downlink communication must be buffered at the network server until the next uplink event.

Class B – Bidirectional end-devices with deterministic downlink latency
In addition to the class A initiated receive windows, class B devices are synchronized to the network using periodic beacons, and open downlink ping slots at scheduled times. This provides the network the ability to send downlink communications with a deterministic latency, but at the expense of some additional power consumption in the end-device. The latency is programmable up to 128 seconds to suit different applications, and the additional power consumption is low enough to still be valid for battery-powered applications.

Class C – Lowest latency, bi-directional end-devices
In addition to the class A structure of uplink followed by two downlink windows, class C further reduces latency on the downlink by keeping the receiver of the end-device open at all times if the device is not transmitting (half duplex). Based on this, the network server can initiate a downlink transmission at any time on the assumption that the end-device receiver is open, resulting in no latency. The compromise is the power drain of the receiver (up to ~50mW) and as such class C is suitable for applications where continuous power is available. For battery-powered devices, temporary mode switching between classes A & C is possible and is useful for intermittent tasks such as firmware over-the-air updates.

In addition to frequency hopping, all communication packets between end-devices and gateways also include a variable Data rate (ADR) setting. The selection of the DR allows a dynamic trade-off between communication range and message duration. In addition, due to the spread spectrum technology, communications with different DRs do not interfere with each other and create a set of virtual ‘code’ channels increasing the capacity of the gateway. To maximize both battery life of the end-devices and overall network capacity, the LoRaWAN network server manages the DR setting and RF output power for each end-device individually by means of an Adaptive Data Rate (ADR) scheme. LoRaWAN baud rates range from 0.3 kbps to 50 kbps. In a highly dense network with end devices close to gateways, the battery lifetime is dramatically increased.

Security is a primary concern for any massive IoT deployment and the LoRaWAN specification defines two layers of cryptography. LoRaWAN embeds security by design:
Unique 128-bit Network Session Key (NwkSKey) shared between the end-device and network server.

Unique 128-bit Application Session Key (AppSKey) between the end-device and the application.

Market overview
In 2018 and beginning of 2019, LoRaWAN development has confirmed LoRaWAN as the leading LPWA unlicensed technology. More than 100M LoRa devices have been deployed across the world, showing a growth of 60 percent in 2018.

The number of operators increased by 61 percent in 2018, reaching more than 100 LoRaWAN operators. 30+ MNO’s are deploying LoRaWAN in parallel to cellular IoT connectivity technologies.

Envisioning the future
When envisioning the future, people may think of disruptive innovations where 80 percent of compelling inventions are incremental and, in a way, very simple to implement. There is a low hanging fruit that is leverage existing Wi-Fi Networks across the world by rolling-out Wi-Fi 6 and LoRaWAN to address new IoT use cases. Nevertheless, let us raise some key areas of collaboration.

Reinforce the strength of unlicensed technologies in 5G
Is anybody challenging the combination of 4G and Wi-Fi today? When our internet web surfing or voice conversation seamless shifts to the mall Wi-Fi hot spot where we are hanging out or going shopping, nobody is surprised. More than 10B devices connected to 200M Wi-Fi Access Points have been invading our private and professional spaces…MNO’s are more than happy to offload 60+ percent of global broadband traffic on Wi-Fi unlicensed networks around the globe. Wi- Fi is clearly referred to as one of the 5G sliced technologies today.

5G needs unlicensed technologies to address all use cases
There is a little doubt that 5G will play a major role in our society’s future. Not many people know that 5G is not just an evolution of 4G. 5G is the first version of 3GPP specifications which opens the standard to any type of communication technology: mobile, wired, fixed wireless, satellite, licensed and unlicensed technologies like Wi-Fi and LoRaWAN. 5G, in its incredible versatility targets to provide value into many verticals.

Conversely, the complexity and breadth of supported use cases means that some will be suboptimal due to 5G simply being too much. This opens the door for right-size technologies instead of reinventing the wheel, to support these applications and one can already see this happening in the market today. 5G main challenge is clearly leveraging millimetre wave’s spectrum (> 6 Ghz) to develop broadband very high throughput services (up to 20 Gpbs!).

LoRaWAN and Wi-Fi cover hundreds of complementary uses cases on each of the 5G market segments: enhanced Mobile Broadband, mission critical communication, and massive Internet of things. Wi-Fi has been engaging for years into 3GPP 5G specification process. Why LoRaWAN would not follow the same route as Wi-Fi? Just looking back as how Operators have been using Wi-Fi in combination with 4G, we have the perfect example of how 5G could leverage unlicensed technologies strong capabilities. Let us not oppose licensed and unlicensed technologies and focus on complementarity to serve any customer use case.

LoRa Alliance and Wireless Broadband have here the opportunity to present a synchronized approach to 3GPP, and at least share valuable information.

Improve interconnection and colocation
Being massively rolled out in the same types of locations like smart home, smart building and smart city Wi-Fi and LoRaWAN need to set-out best practices to interconnect at different levels.
The gateway route of interconnection is already partially addressed via the several implementations of Wi-Fi backhauling of LoRa gateways. We see also use cases of LoRaWAN backing up Wi-Fi in the smart home. In case of Wi-Fi failure, local devices frames are sent to the cloud servers via LoRaWAN network. The biggest challenge to support device scale-up will be to develop Access Points or homehubs fully integrating LoRaWAN gateway.

The cloud route of interconnection is already under implementation, although device authentication process, data models, and security end to end processes could become an area of alignment.
Interconnection discussion might probably start to consider the impact on 5G interconnection.

Increasing massive cohabitation of devices may lead to discussion to best colocation and device setup practices (in smart home for example) to avoid spectrum or interferences issues.

Develop device intelligence
In parallel to the hype of cloud computing-based applications, there is a real development of edge computing or device computing, leading to better handle network issues, as well as optimizing battery consumption by reducing needs of device communication with cloud servers. The goal is to make device more clever or self-sufficient in the decision-making process.

So, the chip interconnect route aims to combine Wi-Fi & LoRaWAN application driven by the device application software and implemented on a chip module (dual source modules). This interconnection route is the most developed today on the ground via dual chip modules in most of geolocation services. Wi-Fi & LoRaWAN location technics are a good example of leveraging strengths of the two technologies.

The emergence of Wi-Fi 6 improving throughput and latency could bring new ideas to develop high throughput functions like Firmware Upgrade Over The Air supporting LoRaWAN devices, transmitted through the Wi-Fi connection of the device, assuming a trade-off on battery consumption. This can be an area of research, like any other applications benefiting from the strengths of the two technologies.

We may imagine a lot of other areas of development. We all know that as usual, the market is going to decide. We probably have here enough on our plate to boost the LoRaWAN and Wi-Fi collaboration based on strengthening the two ecosystem experiences on similar market organizations. LoRa Alliance & Wireless Broadband Alliance.

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