Complete guide to smart home connectivity protocols

Without a common language, we will not be able to communicate with one another.

Similarly, smart home devices rely on a standard communication protocol to exchange information and trigger actions. For instance, a thermostat can sense the room temperature and transmit that data to the air conditioner to regulate the cooling function.

Network reliability, deployment cost, and security are among the primary factors that should be considered when choosing a communication protocol. In which case, both wired and wireless protocols have their fair share of advantages and tradeoffs.

For any smart application, you’ll also need to make sure of network compatibility. Not only do standardized protocols help simplify development for manufacturers, but they also allow customers to enjoy seamless connectivity across smart home products.

In this article, you’ll learn more about the most popular home automation protocols to strategically design future products.

Addressing the Fragmented Home Automation Ecosystem

Despite advances in communication technology, many smart homes are hindered by a lack of network interconnectivity due to competing standards. This increases the confusion of consumers when choosing products for their homes. In fact, one of the major barriers to smart home adoption is fragmented device connectivity (source).

Typical home networks use a combination of Ethernet and WiFi protocols. However, many common networking technologies available in smart devices today, such as ZigBee (open protocol) and Z-wave (proprietary protocol), are not IP-compatible. Consumers still need some form of hub or gateway to connect them to the existing network.

To solve the connectivity challenge, many leading industry players are adopting open protocols over IP to extend connected devices. Furthermore, IP-enabled solutions also address issues of privacy and security.

With that understood, let’s evaluate some basic home automation protocols.

Overview of Common Smart Home Protocols

WiFi

At first glance, WiFi offers the most cost-effective and accessible solution, with high bandwidth. However, in exchange for gigabit data rates, WiFi consumes a lot of power.

Additionally, WiFi suffers from range and reliability issues. The typical communication range measures in the tens of meters, and is quickly reduced by obstructions like walls and ceilings. To overcome range issues, consumers must purchase additional repeaters or range extenders, adding to the cost and complexity of the deployment.

WiFi is vulnerable to a wide variety of interference, which can negatively impact network performance. Users should be wary of counting on WiFi for networks with a large number of devices, since throughput can be reduced while latency begins to add up. This prevents WiFi from being a scalable solution for larger homes.

ZigBee

Zigbee is an open protocol, providing low-bandwidth wireless mesh networking. Through the mesh network, signals can be relayed from device to device without “dialing out” to a WiFi network. It is designed to coexist with WiFi channels without interference (theoretically). However, Zigbee’s frequency sometimes competes with WiFi, since they share the crowded 2.4 GHz channel.

A downside of Zigbee is that it’s a fragmented ecosystem. While ZigBee devices are interoperable, they don’t use IP addressing. Therefore, you need to establish gateways to connect devices to the Internet and cloud services and to other mobile devices. This is not ideal, as gateways are an additional expense and can be complex to set up.

Zigbee is commonly used for dimmers, door locks, and thermostats, etc.

Z-Wave

Similar to Zigbee, Z-Wave is an open source mesh network protocol. But its data throughput is significantly lower. An advantage of Z-Wave is green power usage, suitable for battery-operated devices.

As a proprietary protocol, Z-Wave-enabled devices must be certified by the Z-Wave Alliance to ensure plug-and-play compatibility (but this may change in the future).

Operating in the much lower, uncluttered 908 MHz band, Z-Wave offers low latency and no interference with WiFi, Bluetooth, and other wireless devices that use the 2.4 GHz band.

Z-Wave is commonly used in RFID tags, motion detectors, smoke and gas sensors, among many other sensor devices.

Thread

Developed by a group of companies including Nest, Samsung, QUALCOMM, and OSRAM, Thread is a low-power wireless mesh networking protocol. It shares a lot of similarities with ZigBee. Both are built using open standards, operate on the same hardware layer protocol (IEEE 802.15.4) and utilize the 2.4 GHz band.

The Thread protocol has a huge advantage: it’s IP-addressable (IPv6-based). The defining feature is that it allows devices to continue working even when the WiFi network goes down.

However, Thread-certified products must be built from the ground up to comply with mandatory security features. System integrators need to be strategic with the network design to enable reliable interoperability with existing devices.

Bluetooth

A wireless protocol, Bluetooth networking offers great device compatibility as well as low energy consumption. It facilitates deployment simplicity and flexibility of smart device networks, thanks to the elastic extension and lower latency. The downside is its limited range.

It’s common for wearable devices and sensors.

HD-PLC

HD-PLC is an open standard supported by multiple vendors. It gives you the flexibility to select from multiple vendors with products ranging from discrete transceiver chips to fully integrated system on chips (SoC) solutions.

This powerful communication technology is capable of delivering fast, bidirectional, IP-based communication over any wire. It enables consumers to use existing electrical wiring to communicate over existing wires (twisted pair, powerline, phone lines, coax, etc.). Additionally, it includes a convenient bridging functioning that enables it to connect to Ethernet and wireless networks (WiFi, BLE, etc.) with easy.

Now you can extend IP all the way to endpoints for seamless integration into other IP-based systems. This makes network design and integration easy—and eliminates costly gateway devices, complicated wiring, and complex software development.

In comparison with other wireline technologies, HD-PLC stands out with up to 240Mbps maximum throughput. Utilizing multi-hop technology, it can support up to 1,024 nodes and ranges up to several kilometers.

HD-PLC is designed for IoT applications, download the application guides below to learn more.

Comparison table

Variable	WiFi	Z-Wave	ZigBee	Thread	BLE	HD-PLC
PHY/MAC Standard	Legacy IEEE 802.11.1	ITU-T G.9959	IEEE 802.15.4	IEEE 802.15.4	IEEE 802.15.1	IEEE 1901, ITU G.9960
Frequency Band	2.4 GHz	908.42 MHz	2.4 GHz	2.4 GHz	2.4 GHz	2MHz to 28MHz
PHY Rate	54 Mbps	100 kbps	250 kbps	250 kbps	1 Mbps	240 Mbps
Nominal Range	100 m	30 -100 m	10 – 100 m	10 -100 m	30 m	>2 km
Topology	Star	Mesh	Mesh	Mesh	Scatternet	Free-Topology
Power Usage	High	Low	Low	Low	Low	Low

Conclusion

Among these protocols, WiFi has the advantage of being nearly ubiquitous in homes. However, it comes with challenges like range limitations, reliability issues, and high power consumption.

Low-bandwidth protocols like ZigBee or Z-Wave have several advantages, especially in power-constrained applications. While offering device interoperability, connection to the internet among these devices requires an additional hub.

An IP-based protocol (IEEE 1901-compliant), HD-PLC offers the best integrated network bridge functionality. You can use any HD-PLC-enabled device to bridge PLC networks, Ethernet and serial networks. This integrated Ethernet/WiFi/Serial bridging enables system convergence, so you can connect all devices with other IP-based smart home systems.

Learn more about HD-PLC SoCs and order your evaluation kit here: HD-PLC for Smart Homes