What makes a Smart Home smart? A guide to protocols and applications

Article #2 of the IoT Foundation Series. Smart homes are created by well-matched devices and communication protocols.

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11 Jan, 2022

Together with Digi-Key, a distributor of electronic components, we are creating a series of articles about the technologies that make IoT possible.  This second article examines the protocols of smart homes. Future articles dive into IoT security and connected transportation. 

Introduction

Thanks to advancements in technology, the definition of what a “Smart Home” is has continued to evolve with increasing applications and capacities. However, what has remained constant is the fact that a smart home is made of multiple systems working together to make the home automated, comfortable, and stress-free. 

In recent times, a key driver of the transformation of Smart Home systems has been the internet of things (IoT). The IoT came with the promise of us being able to connect elements and objects in our environment to the internet, and that has led to a huge and dynamic transformation across many sectors/verticals including the Smart Home. Thanks to the IoT, smart home devices which previously just shared data just with one another and within the confines of the home, can now share data on the internet, allowing smart home users the ability to interact with their homes and infrastructure in real-time, from wherever they are. 

This has made smart home solutions “smarter” and created an avenue for several new applications, leveraging cloud computing and machine learning/AI (Artificial Intelligence)to process data, evaluate scenarios in real-time, and make smart decisions beyond the typical pre-programmed logic. These potentials are being harnessed and have led to the emergence of several new smart home devices/solutions. 

The major enabler of smart home systems and the journey to being IoT-enabled are the communication protocols. They provide the infrastructure and dictate the terms by which devices communicate to automate things around the home. This article will provide a guide to the communication protocols and standards enabling the current trends in smart homes. 

Smart Home Communication Protocols 

Smart Home Applications are built around the ability of multiple devices, sensors, and actuators, etc., to talk to one another. From the thermostat talking to the air conditioner to regulate the temperature in the home to motion sensors turning off the lights in an empty room. This makes communication protocols an integral part of smart home applications. However, due to variations in features, capabilities, mode of operation, and requirements, several communication protocols are adopted by manufacturers for various applications. Some of the popular Smart Home communication protocols include:

  1. WiFi
  2. Zigbee
  3. Z-Wave
  4. BLE
  5. Matter

1. WiFi

Arguably the most well-known of the bunch, WiFi offers the easiest and probably the most robust communication path for smart home solutions because of its ubiquitous use in other everyday applications. Most homes would already have WiFi routers which makes deployment of WiFi-based smart home devices easier and cheaper. Its high bandwidth makes it suitable for applications that require high data throughput and its IP-based architecture makes deployment for IoT-based applications relatively easier and straightforward compared to other protocols. 

However, all of the goodies come at a cost that includes high power consumption, short-range, and high susceptibility to interference which makes it unsuitable for most battery-powered smart home applications. There have, however, been several improvements over the years, with the most recent version, WiFi 6, offering better power and range performance. 

2. Zigbee

A very popular communication protocol within the Smart Home community. Zigbee is an Open, flexible (mesh network topology), and low power communication protocol developed on the 2.4 GHz band. It is perfect for battery-based smart home applications but it is not IP-based. As such, Zigbee-based devices require a gateway to connect to the internet for IoT-based applications which increases the cost of deployment. Zigbee offers low bandwidth and sometimes experiences a great deal of interference when deployed alongside WiFi due to competition on the 2.4 GHz band.

3. Z-Wave

Z-Wave is a widely used, low-power focused, proprietary protocol developed by the Z-wave alliance. It operates in a mesh network architecture similar to Zigbee, but operates in the 908 MHz band. It offers low latency, and low interference but comes with significantly lesser throughput compared to the other protocols.  

4. BLE 

Developed by the Bluetooth special interest group, BLE (Bluetooth Low Energy), also referred to as Bluetooth Smart, is a modification to the Classic Bluetooth protocol with low power consumption as one of its major focuses. It's a product of the desire to reduce the amount of power consumed by devices, both when transmitting data and when idle, to ensure longer battery life. However, although it offers simplicity in deployment and low latency, it is severely hampered by its short range.

5. Matter

Developed by the Connectivity Standard Alliance (Previously the Zigbee alliance) and supported by major smart home solution manufacturers including; Apple, Amazon, and Google to mention a few. It is an IP-based protocol that is designed to tackle the interoperability challenges of smart home solutions, providing a framework that enables communication across devices, apps, and cloud services. Matter’s architecture combines the bits and pieces of existing protocols to deliver a potentially one-size-fits-all protocol. The first specification release of the standard features WiFi and thread-based network layers with BLE being leveraged for commissioning.

Architecting Smart Home Solutions: Understanding the relationship between communication protocols and IoT Smart Home Application

While trivial factors like the manufacturer’s preference (the desire to create a line of products with the same protocol etc.) sometimes contribute to the decision-making process, the choice of a communication protocol for smart home systems is ultimately, always dictated by the requirements of the application. Some of the features of the application that determine the protocols used include;

  1. Data Volume 
  2. Power 
  3. Operation Cycle 
  4. Platform Compatibility 
  5. Cost

1. Data Volume

A major feature of Smart Home applications that determines which protocols are used is the amount of data to be transmitted or received. Applications that involve basic sensors and actuators communicating with one another are usually okay with low bandwidth protocols like Z-wave or Zigbee because of the low volume of data being exchanged, but applications involving say video or pictures, etc., high data volume, would require protocols like WiFI because of its high bandwidth and data throughput. 

2. Power

Devices used in Smart Home applications are usually either plugged-in or battery-powered. With power consumption being a major constraint for most of the protocols, how the device is powered is always a major contributor to the choice of protocol. For plugged-in devices, there tends to be more liberality in terms of protocols used, but for battery-powered devices, protocols like WiFi with high power consumption are typically deemed not suitable, forcing manufacturers to adopt more power-friendly protocols like BLE.   

3. Operation Cycle

Smart Home applications require devices to be either “always-on” or come on intermittently between sleep cycles or when triggered by internal/external events. While most applications run devices in the “always-on” mode, intermittent modes featuring some level of sleep periods allow applications (especially those with battery-powered devices) to adopt communication protocols that would ordinarily not be a good fit. For example, a battery-powered device with high bandwidth requirements can adopt a communication protocol with high power consumption like WiFi (all other factors duly considered), leveraging on sleep modes to increase the device’s run time. 

4. Compatibility / Interoperability

Certain applications require integration with devices, apps, etc from different manufacturers. As such, the choice of protocol for such an application is usually one that ensures compatibility across the board. This is one of the major reasons why the different alliances were formed, so devices in the same application ecosystem can easily interact. 

5. Cost

A big part of every engineering decision is cost. For smart home systems, the use of certain protocols for some applications tends to drive the cost of the system higher than the intrinsic value of the application. For example, the cost of a Z-wave gateway might make sense for a lighting management application that involves the connection of a lot of Z-wave-based bulbs to the internet. However, it will make no sense to deploy the same cost in a Z-Wave gateway for a Garage Door control application, hence a different protocol may be required. 

Bringing it together: Smart Home Hubs and Multi-Protocol Hubs/Gateways

Having multiple smart home devices spread across different applications in the home quickly becomes a lot to manage. Different control/interface for each application wears out the user and prevents the attainment of the level of sync that should exist among smart home applications to make the home truly smart and autonomous. 

To solve this, Smart Home Hubs were developed. Smart Home Hubs (bridge or gateways) are hardware devices that allow users to unify their smart home devices so they can be controlled from a single interface.

Beyond the ability to access multiple devices/applications from one interface, hubs allow users to create relationships and interactions between those devices/applications. For devices based on protocols that are not IP-based, hubs are sometimes used to get data from the devices to the internet (and vice-versa).

A typical Smart Home architecture using a Zigbee-based Hub is illustrated in Figure 1.

Figure 1: Smart Home Architecture using a hub.

However, the existence of hubs further revealed the interoperability challenges that have plagued smart home systems due to the multiple protocols. For example, if you get a few Zigbee based smart home devices with a Zigbee based hub, you are “not allowed” to fall in love with a set of other devices/applications based on another protocol other than Zigbee unless you plan to get another hub based on that protocol (Figure 2) or run those devices/applications as standalone. 

Figure 2: Smart home architecture featuring hubs for different protocols.

Multi-Protocol hubs/gateways like the Samsung Smartthings hub and the Wink hub 2 which allow users to interconnect devices based on multiple protocols including Zigbee, Z-wave, WiFi, etc., provide a way around this problem, but they come at an extra price that puts an additional burden on the users and hinders the adoption of smart home solutions.

The interoperability challenges, among other factors, and their effects on Smart Home adoption make the need for protocol/standards unification necessary and this is where a protocol/standard like Matter comes in. 

Matter: Why it Matters

According to research conducted by Google and Accenture in 2020, one of the major barriers to smart home adoptions is the lack of interoperability amongst smart home solutions. According to the report which focussed on the Asia Pacific region; “consumers are either not purchasing devices due to a lack of understanding or not using them to their full extent. In many homes, devices are largely disconnected from one another, meaning the experience is not as seamless, and their smart capabilities are not being fully used”. This is a problem that is clear to all, and smart home solution providers/manufacturers have, over time, made attempts to create a unifying standard/protocol, by coming together to form alliances, a good example of which is the Zigbee alliance.

While a good amount of progress was made, the fundamental challenges with some of the protocols on which the alliances were built, reduced their viability and prevented the alliances from reaching their true potentials. 

This is where Matter comes in, a communication standard architected with simplicity, security, and the kind of elegance required to make homes truly smart and interconnected.
Matter ticks all the boxes the previous alliances and standards failed to. 

Aside from being a protocol that is supported and co-developed by the major players in the smart home industry (a rare feat), Matter extremely matters for the future of IoT-based Smart Home systems because of its Open nature and  IP-Based architecture which gives each device a unique address. These two factors would reduce the complexities in solution deployment and address issues of security and privacy, leveraging on the robust work already done for other IP-based protocols.

Conclusion

Smart home systems are defined by the applications, and as technology continues to advance, especially with the Metaverse now upon us, the applications and capabilities will evolve and become more complex. Communication protocols will keep playing an integral role in these transformations, as such, they must evolve too. The need for a truly integrated smart home experience will increase and with more home devices connected to the internet, the concerns about security, privacy, energy efficiency, etc., will deepen. As such, for a true, integrated smart home experience,  protocols that benefit from all-around knowledge available for security, enable high-level privacy, easier deployment, and improved interoperability needs to come into play. 

Read the first article in the series here. 

 About the sponsor: Digi-Key

Digi-Key is one of the fastest-growing distributors of electronic components in the world. Since its founding in 1972, Digi-Key has been committed to offering the broadest selection of in-stock electronic components, as well as providing the best service possible to its customers, aiding engineers through the entire design process, from Prototype to Production®. 

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