Short Range Wireless Protocol Comparisons

Making the decision on which wireless protocol to implement in a product can be difficult.  Often, the best choice depends on the application, with factors such as range, data requirements, security, network topology support, and battery life.

For the past few years, we have seen most the vast majority of short range wireless implementations boil down to three main options:

Wifi: Primarily used for media streaming, browsing the web, and other data-heavy activities, it’s an efficient high-bandwidth network that draws a relatively large amount of power.

Bluetooth LE: Originally formed to provide a “personal area network”, Bluetooth makes secure communications with nearby devices.  Most Bluetooth devices communicate with each other using a simple one-to-one network topology enabling higher-than-Zigbee bandwidth communications at a fraction of the power of wifi.  Bluetooth has been widely adopted in most industries.

Zigbee:  Characterized by low bandwidth, power, and with the ability to mesh network, Zigbee has been able to extend to long range and can run for years on a small battery.  Communication often needs to occur through a hub as signals aren’t directly compatible with most mainstream computing devices.

For many new IoT applications, these protocols are being weighed, measured, and even combined to achieve desired results.  However, with the recent introductions of Bluetooth LE, Bluetooth 5.0 and BLE Mesh, we may start to see a tipping of the scales.

Bluetooth, A Quick Introduction

Bluetooth was originally released in 2000. It quickly became the dominant technology for wireless audio products as well as many products that require a person to have a close physical proximity to the device.  Bluetooth allows one device to communicate with another, using a simple point-to-point connection that in effect, could be equated to an invisible serial cable.

In 2010, Bluetooth Low Energy (LE) provided the next major step forward. Its impact has been substantial and widely felt, most notably in smartphones and tablets, as well as in health and fitness, the smart home and wearables categories.  In addition to the continued support of point-to-point topologies, Bluetooth LE also allowed devices to broadcast data so that one broadcasting device can communicate with many listening devices, supporting one-to-many device communications. Bluetooth beacons operate in this manner, spurring a huge increase in industrial use-cases including RTLS (Real Time Location Systems).

In late 2017, SIG released mesh networking support to Bluetooth. Bluetooth mesh supports complex, many-to-many communication between devices so that any device in the mesh network can communicate with any other device in the network, a capability that puts it in further competition with Zigbee. Messages are relayed across the network in a series of “hops”, allowing networks to span very large physical areas without the need to be in direct radio range of each other. The mesh protocol stack uses Bluetooth LE for radio communications and inherits its power efficiency, low latency and other traits that have made Bluetooth LE so popular.

Implications of Bluetooth Mesh

The addition of Bluetooth Mesh is a major step forwards for Bluetooth, positioning it for use across a range of new applications and industry sectors.  Bluetooth mesh uses a message-oriented communication pattern known as publish-subscribe. This poses as a huge benefit for many product applications in the industrial and smart home space including smart devices such as locks, appliances, equipment, and lights.

Devices can be added or “provisioned” to the network without other nodes being adversely affected by the change. For example, a home owner can buy one Bluetooth mesh enabled smart lock for the front door, and then decide a week later to buy 6 more for the rest of the home, along with 10 BLE Mesh lights, a garage door opener, and 4 sprinkler heads. All of the devices can be seamlessly organized, provisioned and controlled within a single application on the home owner’s mobile.  Furthermore, the owner will be able to control all of the devices simultaneously from anywhere in the home as publish messages will “hop” to the corresponding device, regardless of whether the mobile phone can connect directly to the subscriber.

Figure 1: Bluetooth mesh features Proxy (P) nodes that allow today’s smartphones to control applications such as smart lighting. (Image source: Bluetooth SIG)

As more eloquently described by the Bluetooth Alliance,

” Commercial lighting provides a natural grid for connectivity. Add Bluetooth® mesh networking into the mix and retailers will have the potential to offer in-store navigation and customized promotions. Hospitals will be able to track patients and expensive equipment. Factory floors will be able to connect machines and perform automated monitoring and maintenance. And businesses will have the power to intelligently control lighting, temperature and air conditioning and to monitor occupancy and security. Sensors can be installed in all corners of the building and, thanks to the power efficiency of Bluetooth mesh networking, run off small batteries for many years, allowing the capture of valuable data.”

It’s hard to find a smartphone or tablet which does not already support Bluetooth LE. Bluetooth mesh, which uses Bluetooth LE as its underlying radio communications component, makes it possible for current in-market smartphones and tablets to securely interact with mesh nodes.

Bluetooth mesh networking brings the multi-vendor interoperability, low power and low latency pedigree that is ideal for many IoT projects. It’s designed to allow the creation of reliable, responsive, secure and scalable wireless systems.

Making the Decision

Given the nuances of different wireless technology, the choice of which to use comes down to the requirements of the application, making it useful to utilize a comparative table (Table 1).

Table 1: Comparison of key protocols for IoT applications. (Data source: Digi-Key, Texas Instruments)

Although we have spent some time going over some of the new features of Bluetooth, every wireless technology is evolving, both to compete with rivals and to meet the demands of new, and often unanticipated applications.

Any technologies will do a satisfactory job, but as shown, some use less power, others offer better throughput. Some offer long range, others offer smartphone or wireless access point interoperability.

All of these are proven low power wireless technology options backed by good design tools and vendor support. The choice always comes down finding the best specification for the application.