Zigbee, BLE and Bluetooth Mesh, how to choose the best solution?

In the world of IoT, wireless communication technology enables more and more IoT devices to interact with each other and form a large network. Today, there are many protocols competing for market dominance. Among them, Zigbee and Bluetooth Low Energy (BLE) are two standards built for low-power IoT applications because of their low cost and simple development.

However, there are some differences between them. In certain situations, one protocol may be more suitable than the other. And in some cases, combining the two may be the best course of action to take advantage of their complementary advantages. Next, we will compare and discuss BLE and ZigBee, which are common in the Internet of Things, as well as their advantages, use cases, and limitations.

Differences between Zigbee and Bluetooth Low Energy (BLE)

BLE is a Bluetooth-based protocol that enables short-range communication between devices and can provide faster data rates than Zigbee. Therefore, BLE may be a better choice for IoT applications that need to transmit relatively large amounts of data.

Zigbee is a protocol based on the IEEE 802.15.4 standard, which focuses more on the stability and reliability of the network. Zigbee supports more nodes and can build larger networks, which is crucial for IoT applications that need to connect a large number of devices, especially projects with higher requirements for stability.

The ecosystems of BLE and Zigbee are also different. Due to the widespread use of Bluetooth in consumer electronics such as smartphones and tablets, consumer electronics devices are more mature in supporting BLE. On the other hand, Zigbee is more widely used in home automation and can be used with more sensors and actuators.

Zigbee in the Internet of Things

Zigbee is a low-power wireless mesh networking standard based on the IEEE 802.15.4 specification. In most countries around the world, Zigbee uses industrial, scientific, and medical (ISM) radio channels, including 2.4 GHz. Zigbee is suitable for battery-powered devices in medium-range wireless control and monitoring applications.

• Mesh Network: Zigbee operates on a mesh topology network. Messages reach distant nodes through intermediate nodes, which means that data from a single sensor node is transmitted across a set of patterns until the transmission reaches a universal Zigbee gateway. This has the advantage of greater network coverage (theoretically a single network can accommodate up to 65,000 nodes) and long distances, but also has the disadvantage of higher latency due to bottlenecks when multiple nodes try to reach the gateway through a single node.
• LAN Local Area Network: Zigbee is designed to transmit data over short to medium distances. It is able to share information between multiple devices simultaneously using a mesh architecture network.
• Low bandwidth: Zigbee radios have very strict limits on power and bandwidth, and are suited to transmitting data in small packets.
• Cost-effectiveness: Zigbee is a license-free, open global standard developed by the Zigbee Alliance and can be implemented without any license. Therefore, the cost of Zigbee is not high.
• Suitable applications: Zigbee is a good choice for small projects with high node density. It is well suited for IoT smart lighting systems and home automation. However, Zigbee is not widely adopted in large projects because a large number of nodes may take the same path at the same time and create bottlenecks. Therefore, Zigbee is still quite limited in industrial IoT applications such as highly instrumented installations.

Advantages of Zigbee

• Reliability: One of the great advantages of Zigbee mesh networks is their “self-forming” and “self-healing” nature. Zigbee mesh networks can automatically form and configure if any nodes are added, and repair or replace any damaged or disabled nodes in the network.
• Interoperability: Zigbee devices from different manufacturers can communicate seamlessly, contributing to Zigbee's widespread acceptance and lower costs in the IoT space.
• Easy to develop: The Zigbee Alliance released the official IEEE 802.15.4-2003 Zigbee specification in late 2004, and the specification has gone through several revisions. As a result, documentation for developing Zigbee is widely available and covers many different use cases. Routing tables, address resolution, security, retries, and acknowledgments are all built into the protocol, saving a lot of engineering time.

Limitations of Zigbee

• Non-IP: Zigbee does not use IP addressing. Therefore, a Zigbee gateway must be installed to help communicate with the Internet and cloud services.
• Always powered: Most mesh networks have the limitation that all connected nodes routing or hopping messages must remain powered at all times, which can be a bit of a power drain.
• Latency: Due to the mesh topology of the network, Zigbee networks can have higher latency than simple point-to-point communication.

Zigbee in IoT Use Cases

For low-cost, low-power IoT-based home automation networks, Zigbee is undoubtedly the best choice due to its interoperability. After all, Zigbee's origins are in home automation. In addition, it is also suitable for commercial and industrial applications, including home energy monitoring, IoT lighting, elderly home monitoring systems, etc.

Smart city street lighting is a good example of the Zigbee mesh networking trend as it allows a fairly large network of devices to be remotely controlled with the help of outdoor industrial Zigbee sensor-to-cloud gateways.

Bluetooth Low Energy in the Internet of Things

Bluetooth Low Energy (BLE) is one of the most widely used communication technologies in various fields of the Internet of Things today. BLE was created and promoted by the Bluetooth Special Interest Group (Bluetooth SIG).

• Short-range communication: BLE is primarily used to establish a point-to-point connection between two different devices on a personal area network (PAN).
• High-speed transmission: Bluetooth’s overall range is smaller than Zigbee, but BLE’s data rate is much higher. Bluetooth 5 can send and receive data at up to 2 Mbps, which is three times the transmission rate of the previous generation standard.
• Interoperability: The Bluetooth SIG coordinates interoperability between device manufacturers by setting aside a significant portion of the UUID value space for member companies to create unique Bluetooth application services and making the assigned UUID numbers public to avoid communication conflicts.
• Low power consumption: BLE stands for Bluetooth Low Energy and has excellent power management capabilities. BLE devices support low-bandwidth connections and handle small data streams, allowing the battery to last for months or even years. Typical BLE devices include battery-powered Bluetooth beacons, digital scales, IoT temperature and humidity sensors, lighting controllers, smart watches, etc.
• Suitable applications: BLE is well suited for implementation in IoT solutions that require continuous data transmission at a high rate over a short distance. However, BLE networks are limited by bandwidth and physical coverage, so BLE is not the best choice for high-density node applications.

Advantages of using BLE

• Less complex hardware: Bluetooth low energy implements a client-server architecture, and the hardware can usually be customized to implement only the communication features required.
• Low development cost: BLE is a simple protocol that is widely accepted and implemented in billions of devices worldwide. Its larger ecosystem has led to the mass production of BLE SoCs and further reduced IC costs compared to Zigbee. At the same time, it supports many popular IoT operating systems, including Android, Windows, iOS, etc., making it easier to develop BLE embedded applications and verify their functions, which will greatly reduce engineering costs and development time.
• Excellent power management: As the name implies, Bluetooth Low Energy is a well-optimized protocol that does not consume a lot of power. It can be implemented in data-hungry IoT devices that can run for long periods of time on coin cells and go unattended for months at a time.

Limitations of using BLE

• Point-to-point communication: BLE is a point-to-point protocol. One BLE device acts as a master and the other as a slave, which can lead to limited scalability and high deployment costs. In a typical BLE connection, there is usually communication between a central device (such as a BLE gateway) and one or more peripheral devices (such as sensors or actuators).
• Lack of IP addressing: Bluetooth Low Energy (BLE) is a different protocol than the Internet Protocol (IP), and BLE devices do not have IP addresses. To transmit data from a BLE-only device to the Internet, another BLE device with IP connectivity is required to receive this data and then forward it to another IP device (or the Internet) and cloud solutions.
• Limited range: The network coverage is quite limited, which is one of the core disadvantages of BLE. Usually, BLE radios cannot communicate outside the maximum range. It is OK for home and office use cases, but not so good for industrial and agricultural monitoring applications. Therefore, Bluetooth Long Range (BLR) was invented to significantly increase the signal transmission distance at the cost of signal transmission rate.

BLE in IoT Use Cases

Home automation has proven to be one of the best use cases for Bluetooth Low Energy to link a collection of objects in a specific area. Popular smart products using BLE capabilities include wearable home health monitoring devices, elderly home monitoring devices, and home entertainment devices.

BLE is also perfect for indoor positioning and navigation, as BLE beacons can be used to determine the location of a person within a factory or parking lot.

Another important market is BLE-based lighting control in building automation or small commercial environments. BLE is well suited for automating small IoT-based greenhouse monitoring systems, but may not be the best choice for larger IoT systems. Changing the ambient temperature or lighting intensity in a greenhouse can help promote plant growth.

Bluetooth Mesh in IoT

Zigbee is the most popular mesh networking protocol today, and the Bluetooth SIG released a similar Bluetooth mesh networking standard in 2017 in an effort to solidify its dominance in wireless technology.

BLE Mesh goes beyond the limitations of the conventional BLE protocol and can establish a stable and flexible network between a large number of devices. It allows many-to-many devices to communicate through multi-hop connections to achieve wider coverage. Although BT Mesh can accommodate more than 32,000 nodes, a single network is usually limited to a few hundred devices due to actual bandwidth and physical space limitations.

Advantages of BLE Mesh

Bluetooth Mesh is used to control lighting, curtains, and other smart devices in smart homes. It can also be used for IoT remote monitoring and sensor networks, and even for large-scale industrial automation systems and IoT lighting for smart building automation.

• Large physical network: Because Bluetooth mesh devices can connect to each other through multiple hops, information can be passed through intermediate nodes, making the network stronger, wider, and not limited by the range of any one radio node.
• Beacon broadcast communication: Bluetooth Mesh is based on BLE and carries the capabilities of the protocol, such as supporting beacons and broadcasting beacon information, but only the target device processes the information, enhancing privacy and security.
• Low energy consumption: Bluetooth Mesh devices based on the BLE protocol generally have low energy consumption and are suitable for battery-powered devices. In addition, the transmission range of mesh network nodes is shorter, thereby reducing power consumption.
• Reliability: Devices can automatically join the network, establish connections, and transfer data without the need for a central controller because the Bluetooth LE Mesh network is self-forming and self-healing.

Limitations of using BLE Mesh

• Latency: MTU size (Link layer Maximum Transmission Unit) is an important criterion for evaluating performance. BLE has a smaller MTU size, which will add more latency and cause performance degradation if higher layer protocols or applications intend to use larger packets.
• Mesh routing limitations for highly congested and large networks: BLE uses a managed flooding approach to route mesh packets, where only nodes on primary power will relay packets. This router mechanism works very well when the network is small and the nodes are mobile. But it can face some challenges with higher latency due to the MTU size limitations we mentioned earlier. In this case, Zigbee tends to perform better due to its mature routing approach.
• Missing IP addressing: To achieve full-fledged IoT connectivity and control over the Internet (or the cloud), a BLE mesh gateway is required to convert BLE packets into IP network packets and vice versa.

BLE Mesh in IoT Use Cases

It is worth mentioning that Bluetooth mesh technology is currently in the early stages of development and may be enhanced and revised. Since most lighting devices can easily obtain continuous mains power, and the router node requires power, Bluetooth mesh is very suitable for controlling lighting in buildings. When a Bluetooth mesh lighting control network powered by mains power is already available, it is simple to establish a sensor network based on BLE mesh network.

Combining BLE and Zigbee in IoT

Both Zigbee and BLE are excellent choices for creating IoT devices and applications, although they have more similarities than differences. It is important to understand the pros and cons of each, but if Zigbee and BLE can be merged to create a more advanced and powerful wireless IoT network, that is what we are looking for.

Therefore, choosing Bluetooth or Zigbee depends on the specific IoT application requirements. If high data rates and improved user experience are required, BLE may be a better choice. If a larger network and higher reliability are required, Zigbee is obviously a better choice. In some cases, the two protocols can also be used in combination to obtain better performance and functionality.

Frequently Asked Questions about Zigbee and BLE

1. Can I use a smartphone as a Bluetooth gateway?

Yes, many BLE applications are built to use a mobile phone as a gateway. However, this only works when the smartphone is nearby and only works with wearable devices such as smartwatches or fitness bands. Since sensors used in commercial and industrial applications are often unattended, implementing a smartphone as a gateway is difficult and expensive.

2. Why use mesh topology network in IoT deployment?

IoT devices and use cases are rapidly expanding across all sectors and businesses. As this is happening, there is a need to create decentralized networks of nodes to solve some of the problems posed by traditional point-to-point, star, or hub network topologies, where IoT devices must interact through Wi-Fi routers despite being in close physical proximity.

In a mesh topology, each node or several of them are transformed into routers, which, in addition to consuming data, are also responsible for sharing data with neighbors. This creates a network of routers and end nodes, which improves the decentralization, scalability, and reliability of the network.

As long as no node is too far from another node, each node will receive the data packet directed to it, and it is simple to add or remove nodes from the network. At the same time, there is no single point of failure in the network. A single Mesh gateway can aggregate the data of multiple nodes to the Internet, improve the efficiency of data transmission between nodes, and reduce costs.

3. What is the difference between Bluetooth mesh and Zigbee mesh hardware?

Since Bluetooth mesh is very new, there may be issues that take some time to resolve. On the other hand, it will take some time for the technical documentation to become more comprehensive and for compatible devices to enter the market. As the technology matures, Zigbee's hardware compatibility has also improved. Zigbee-specific microcontrollers and SoCs are already widely used.