When building Internet of Things (IoT) solutions, two of the most commonly used wireless technologies are Zigbee and Wi-Fi. Both offer distinct advantages and disadvantages for connecting IoT devices.
So which one is right for your needs - Zigbee or Wi-Fi?
This article provides a comprehensive overview comparing Zigbee and Wi-Fi.
We'll examine how they work at a technical level, key differences in capabilities, ideal use cases for each, and how the two technologies can coexist. By the end, you'll know to decide which technology fits best for a given IoT project.
What is Zigbee?
Zigbee is a low-power, low-data-rate wireless networking standard designed for IoT and machine-to-machine (M2M) applications. Here's an overview:
Zigbee definition: It is a specification based on the IEEE 802.15.4 standard for local area networks. The Zigbee Alliance, an organization of companies that maintain and publish the standard, ratifies recommendations for interoperable products.
Zigbee technology overview: It operates in various unlicensed frequency bands including 2.4GHz (global), 900MHz (Americas, Australia), and 868MHz (Europe). The specifications define network, security, and application software layers built on top of the IEEE 802.15.4 standard.
Zigbee devices and applications: Its low power consumption allows battery-operated devices to run for months or years before needing replacement. Typical applications include smart home devices (lighting, thermostats, locks), industrial IoT sensor networks, healthcare monitoring, and automation systems.
So in summary, Zigbee provides specifications for low data rate monitoring and control networks optimized for embedded systems with longer battery life.
What is Wi-Fi?
In contrast to Zigbee, Wi-Fi is a higher bandwidth wireless data networking standard commonly used for Internet access:
Wi-Fi definition: The Wi-Fi Alliance defines and certifies Wi-Fi standards based on the IEEE 802.11 specification for wireless local area networking (WLAN). 802.11 is the set of original WLAN standards first released in 1997.
Wi-Fi technology overview: Wi-Fi devices primarily operate on the 2.4GHz and 5GHz frequency bands. Key enabling technologies include OFDM modulation for high throughput and advanced antenna technology such as MIMO. The latest standard is 802.11ax, which introduces higher data rates and better efficiency for dense device environments.
Wi-Fi devices and applications: Wi-Fi is nearly ubiquitous - used in smartphones, laptops, tablets, smart home hubs, industrial data capture devices, and more. High-speed data rates above 1 Gbps enable applications like 4K video streaming. But more power is needed compared to Zigbee.
In summary, Wi-Fi provides high-bandwidth wireless data networks for devices to connect to the Internet and each other. Next, we'll compare technical capabilities.
Zigbee vs Wi-Fi: Key Differences
While both are wireless standards useful for IoT, Zigbee, and Wi-Fi take vastly different approaches optimized for their target applications. Below we highlight some of the major differences:
Communication protocols - Zigbee uses a mesh network topology so each device can relay data, extending coverage. Wi-Fi is based on star topology where devices communicate via a central access point.
Frequency bands - As discussed earlier, Zigbee uses IEEE 802.15.4 radios on unlicensed bands below 1GHz. Wi-Fi typically uses 2.4GHz and 5GHz ISM bands.
Data transfer rates - The latest Zigbee 3.0 specification has maximum data rates up to 250 Kbps. 802.11ax Wi-Fi achieves over 1Gbps! So Wi-Fi has over 1000 times higher throughput.
Power consumption - Zigbee protocol and radios are designed for low power. Wi-Fi devices use more computing horsepower and high bandwidth radios that draw substantially higher current.
Range/coverage area - A Zigbee mesh network in optimal conditions can extend up to 1km (.6 miles). An 802.11ac Wi-Fi network provides coverage to over 35 meters indoors.
Number of devices supported - Each Zigbee coordinator or gateway can support thousands of low-traffic end nodes. A Wi-Fi access point typically supports less than 100 concurrent client connections.
Security - Both employ advanced encryption: Zigbee uses 128-bit AES encryption while WPA3 Wi-Fi mandates 128+ bit protection.
| Feature | Zigbee | Wi-Fi |
|---|---|---|
| Network Type | Mesh network | Star network |
| Data Transfer Rate | Up to 250 kbps | Up to 9.6 Gbps (Wi-Fi 6) |
| Power Consumption | Very low | Moderate to high |
| Range | Up to 100 meters | Up to 30 meters (2.4 GHz), up to 100 meters (5 GHz) |
| Security | AES-128 encryption | WPA2/WPA3 encryption |
| Cost | Generally lower cost per device | Wide range of costs depending on device and features |
| Applications | Smart home sensors, light switches, thermostats, wearables | Computers, smartphones, tablets, streaming devices, smart TVs |
Bottom Line
Zigbee sacrifices data bandwidth to gain ultra-low power operation while Wi-Fi is designed for high-speed data throughput.
Choose Zigbee: If you need a low-power, long-range, and reliable network for simple devices like sensors and light switches.
Choose Wi-Fi: If you need high data transfer rates for streaming, downloading, and connecting multiple devices.
Zigbee vs Wi-Fi: Pros and Cons
Given the significant differences in technical design, Zigbee and Wi-Fi each shine for particular applications. Below we summarize the pros and cons of each standard:
| Zigbee Pros | Zigbee Cons |
|---|---|
| Ultra low power - battery operation for years | Very low data rates |
| Inexpensive, simple devices | Small coverage area per device |
| Reliable mesh networking | |
| Thousands of nodes per network |
| Wi-Fi Pros | Wi-Fi Cons |
|---|---|
| High speed data enables advanced applications | Higher power consumption decreases battery life |
| Ubiquitous coverage leveraging existing routers | Comparatively higher cost per device |
| Advanced security protocols | Interference and congestion on popular bands |
Use Cases and Applications
Now let's examine which technologies are best suited for specific IoT applications. We'll compare use across smart homes, industrial IoT, healthcare facilities, commercial buildings, and more.
Smart Home: Home automation including lighting, thermostats, appliances, and security systems need battery-powered sensors and controls with moderate bandwidth. Here Zigbee shines when compared to Wi-Fi. Zigbee gateways then connect devices to home routers via Wi-Fi or Ethernet.
Industrial IoT: In manufacturing plants, warehouses, and other industrial environments, Zigbee often displaces wired sensor systems. Thousands of low-cost battery-operated devices can be deployed to monitor equipment across wide areas without wiring. Small amounts of sensor data are relayed to centralized computing systems over the mesh network.
Healthcare: Wi-Fi supports patient and asset tracking in hospitals along with high bandwidth needs like wireless medical imaging transfer. Zigbee monitors low-bandwidth medical sensors and equipment, notifying caregivers if someone leaves a room or needs assistance.
Commercial Buildings: For HVAC, security systems, and lighting, Zigbee's mesh topology provides extensive coverage across large buildings utilizing gateways to existing wired Ethernet backhaul and Wi-Fi networks. Wi-Fi directly connects computers, phones and tablets used by workers.
So which technology do you choose? In many cases, Zigbee handles low-power sensor networks while Wi-Fi transports data to computers and the cloud. Next, we'll examine how they work together.
Coexistence of Zigbee and Wi-Fi
In the previous section, we saw Zigbee and Wi-Fi can play complementary roles - low-power mesh networks paired with high bandwidth backhaul pipes to the Internet. However, since the popular 2.4GHz band is shared between the two protocols, interference must be mitigated. Below we introduce coexistence strategies.
Strategies for Reducing Interference
The first technique places Zigbee and Wi-Fi on separate bands - Zigbee stations on 868MHz or 915MHz while Wi-Fi remains on 2.4GHz. Otherwise, a few approaches help reduce collisions:
Zigbee adapts frequencies to avoid Wi-Fi traffic through channel scanning and blacklists
Wi-Fi controllers can detect Zigbee transmissions and avoid those frequency blocks
Packet retransmissions handle a limited amount of interference
Using Both Technologies Together
Once coexistence issues are addressed, Zigbee and Wi-Fi work together extremely well. Common combinations include:
Zigbee sensor networks connected via gateways to Wi-Fi infrastructure
Devices with dual Zigbee and Wi-Fi radios (e.g. smart lighting)
Zigbee backhaul networks enhancing Wi-Fi coverage
So proper planning facilitates deploying these technologies in concert to build robust, full-featured wireless networks.
The Future of Zigbee and Wi-Fi
Both Zigbee and Wi-Fi continue to evolve with new standards and capabilities on the horizon. Let's take a look at what the future holds for these essential wireless protocols.
Emerging Trends and Innovations
The Wi-Fi Alliance members are developing Wi-Fi 6E which adds 6GHz support for up to 14 additional 80MHz wide channels as an extension of Wi-Fi 6. This boosts capacity, reduces latency, and will be supported on new smartphones/tablets.
For Zigbee, the Connected Home over IP project led by Amazon, Google, Apple, and others aims to increase compatibility between disparate IoT wireless standards including Zigbee. Chip vendors like NXP Semiconductor are also releasing Zigbee platforms that integrate with Amazon's Alexa voice assistant.
New Standards and Specifications
On the standards front, the IEEE Ratified 802.11ax in 2019 which delivers faster speed, increased range, and lower latency. The Wi-Fi Alliance subsequently introduced its interoperability certification under the brand name Wi-Fi 6.
Like Wi-Fi, Zigbee continues to update its specifications. Zigbee 3.0 released in 2015 added high packet rates up to 250 kbps and faster mesh network formation to boost responsiveness.
Projected Growth and Adoption Rates
Research firm IoT Analytics predicts the number of Wi-Fi-connected devices will quadruple to over 5 billion by 2025. Commercial usage accounts for most of this growth as enterprises adopt Wi-Fi 6.
Meanwhile, Zigbee's low-power operation helps industry experts forecast a substantial expansion of battery-powered Zigbee sensor nodes over the next decade across smart homes, cities, and energy infrastructure.
So in summary, both wireless standards continue their momentum with new versions enabling cutting edge applications.
Conclusion
The choice between Zigbee vs Wi-Fi need not be an either/or decision for many IoT use cases. The two technologies complement one another extraordinarily well.
Zigbee provides the ultra-low power mesh networks perfect for intermittent data and control signals from inexpensive sensors and actuators across wide areas. Wi-Fi acts as the high-speed on-ramp to handle data aggregation and cloud integration over existing infrastructure.
Want to learn more about Zigbee? Check out my article comparing Zigbee to Z-Wave.