Mouser Electronics Whitepaper
Wireless Communication: An Overview of Established and Emerging Technologies From Wi-Fi and Bluetooth to WiGig and WirelessHD, we look at the characteristics and key applications of existing and new wireless communication technologies By Mark Patrick, Mouser Electronics
Mouser Electronics Whitepaper
Wireless communication is deeply embedded in the way we live, work and play. Whether it’s browsing the web from your couch, paying for shopping with your contactless card, or turning down the lights from your smartphone, most of us make use of the technologies without even thinking about them. For those buying electronics systems, however, the way devices communicate is extremely important. For example, any new system you procure is likely to need to integrate with others you already have (or may buy in the future). If one uses a completely different communications technology from another, getting the two talking to one another could be challenging or even impossible. Equally, the equipment needs to use a communications technology that’s suitable for the environment you intend to deploy it in. This is why we’ve put together this guide to the major wireless communications technologies in use today, including Wi-Fi, Bluetooth, Zigbee and Z-Wave. We explore the key characteristics of each and outline some practical applications, to help you understand where each could fit into your ecosystem. We also look at some emerging technologies to watch out for.
Contents Wi-Fi...................................................................... 3 Bluetooth.............................................................. 4 Zigbee and Z-Wave.............................................. 5 RFID and NFC...................................................... 6 Emerging Wireless Technologies........................ 7 The Challenges for Designers and Procurers.... 7
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Wi-Fi When someone mentions wireless communication, the first thing that generally comes to mind is Wi-Fi. Now found just about everywhere, Wi-Fi works by creating a wireless local area network (WLAN) to which computers, phones, tablets, smart home appliances and other electronic equipment can connect. All these devices can communicate via a central access point, which generally also connects the WLAN to the internet. Wi-Fi can also create so-called “ad hoc” networks directly between devices, without an access point. Wi-Fi has been around a long time, and has evolved considerably since it was first launched, bringing increased speeds and improved security. IEEE standard 802.11 defines the hardware and communication protocols, and the Wi-Fi Alliance group sets out certification procedures and interoperability testing. Any product or system that wishes to display the famous Wi-Fi logo must follow these procedures. Wi-Fi uses two frequency bands (2.4 GHz and 5 GHz). Its indoor range can be as high as 30 meters, but this will often be hampered by walls and other obstructions. Interference from other devices using the same frequency bands is another inhibitor of range: Bluetooth also operates on the 2.4 GHz band, as do devices such as baby monitors.
Wi-Fi versions are denoted by the revision of the standard in which they were first defined. 802.11b was the first to be widely taken up. New devices will be backward-compatible, so an 802.11n device supports that version of the standard and all those that came before. The current standards are: • 802.11b: The basic 2.4 GHz standard. • 802.11a: The original 5 GHz standard, which provides higher speeds but lower range. • 802.11g: An upgraded version of 802.11b – up to three times faster, as a result of changes to the way data is encoded. • 802.11n: This improves both speed and range (as high as 70 meters indoors), using several antennae at both 2.4 GHz and 5 GHz to “beamform,” which points the signal toward the target device. • 802.11ac: This enables more antennae and new encoding schemes, resulting in significantly higher data rates on the 5 GHz band. • 802.11ax: This variant makes more efficient use of the available spectrum, thereby creating possibilities for up to four-times greater data throughput and higher device densities. Product designers who want their devices to communicate over Wi-Fi can buy off-the-shelf modules that include all the necessary circuitry, antennae and a microcontroller, as well as the software to handle communications. By choosing modules that have been certified by their manufacturers, it becomes relatively straightforward to add Wi-Fi to a product.
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Bluetooth Alongside Wi-Fi, Bluetooth has become extremely common. It was originally designed as a replacement for wired connections in devices located close together. This creates what’s often called a “wireless personal area network” (WPAN). As mentioned above, it also uses the 2.4 GHz frequency band, but was originally aimed at applications requiring shorter ranges and lower data rates than Wi-Fi. More recently, Bluetooth’s low energy consumption has made it an attractive communications technology for low-power Internet of Things (IoT) devices. This is why recent iterations of the standard have focused on improvements that extend its range and further reduce its energy consumption. Popular uses for Bluetooth include: • Linking cell phones with wireless headsets • Linking a phone to an in-car audio system for hands-free calls and music • Connecting devices to portable speakers • Pairing wearable fitness trackers and smart watches to phones or computers • Wireless computer keyboards and mice • File transfers between devices
The boom in wearable technology, electronic healthcare devices and the broader IoT is expected to drive significantly increased demand for Bluetooth technology. Annual Bluetooth integrated circuit shipments totaled around 1.6 billion units in 2016. This nearly doubled in 2017, and is predicted to hit five billion by 2021, according to ABI Research. The standard is overseen by the Bluetooth Special Interest Group (SIG), which manages its development, and the Bluetooth Qualification Process, which all devices must complete. The SIG owns the trademarks, meaning the name and logo can only be displayed on devices that have successfully completed qualification. An interesting fact about Bluetooth is that it’s named after a Danish king, Harald “Bluetooth” Gormsson. He reigned during the 10th century and united a number of tribes into a single kingdom – the analogy being that Bluetooth brings together multiple electronic devices into a single ecosystem. The Bluetooth logo is a combination of the two runes for King Harald’s initials.
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Zigbee and Z-Wave While Bluetooth (specifically Bluetooth Low Energy) is an increasingly popular choice for applications such as home automation, it’s not the only wireless technology being used in this space. Zigbee and Z-Wave are two other options, both designed to be low-cost and use very small amounts of energy. The latter is an important factor, given that some of the sensors or controllers in these environments need to operate for months or even years on a very small battery. Consequently, the range and bandwidth you get with Zigbee and Z-Wave is limited to tens of meters on a line-of-sight basis. However, both technologies are perfectly suitable for applications where only small amounts of data are transmitted intermittently. Home alarm systems, light switches, thermostats and even industrial control systems are example uses.
Zigbee is an open standard that’s defined by the Zigbee Alliance industry group. Any product design needs to pass the group’s validation tests. Conversely, Z-Wave is proprietary, owned by Silicon Labs (with Mitsumi sometimes serving as a second-source supplier). Its bandwidth is lower, but its range longer than Zigbee’s. Overall, Z-Wave is regarded as generally simpler to implement, but not as flexible as Zigbee.
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RFID and NFC Elsewhere in the wireless communication world, radio frequency identification (RFID) and its subset, near-field communication (NFC), are popular technologies when it comes to access control systems, product tracking and other contactless use cases. In logistics and stock control, RFID tags are a common means of tracking the location of items along a production line or a warehouse. These tags are similar to the security ones you find attached to goods in shops, which have to be taken off or neutralized when you pay for the items. The technology is also used in building access control passes, electronic passports and payment systems. An RFID system consists of tags (which store data) and readers. The reader accesses data on the tags using electromagnetic induction between loop antennae in the tag and the reader. Tags come in two varieties. Active tags include a battery, enabling them to generate their own radio signal, meaning they offer greater range, but higher costs and shorter lifetimes. Passive tags, on the other hand, harvest energy from the signal picked up by their antennae. This limits their range, but makes the tags cheaper.
Unlike the technologies we outlined above, there’s no single standard for RFID. A variety of industry bodies and national organizations have created their own, alongside various proprietary systems. To further complicate matters, different countries may use different radio frequencies, meaning a tag from Europe may not work in the USA, for example. Moreover, RFID tags generally offer limited security, and there are privacy concerns when it comes to potentially tracking people who are wearing or carrying products with tags attached. NFC, on the other hand, is a standard defined and promoted by the International Organization for Standardization (ISO) and other groups, such as the NFC Forum. NFC enhances the technology underpinning RFID to enable more flexible inter-device communication. Under NFC, a device can be both a reader and a tag, meaning communication can be two-way, peer-to-peer. There’s also better security built into NFC, which means it can be used for contactless payments, access control and other applications where security is paramount.
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Emerging Wireless Technologies Where the likes of Wi-Fi and Bluetooth have already drastically reduced the number of physical cables we have in our lives, a quick look around your home will doubtless show there are still many remaining. New and emerging technologies, including WiGig and WirelessHD, are seeking to remove some of these, such as the links between televisions and games consoles, where low latency is essential. These technologies typically achieve higher data rates than Wi-Fi by using much higher frequencies (60 GHz). Because the signals can’t pass through walls or people, these technologies operate on a line-of-sight basis between devices, with ranges up to around 10 meters. Using WiGig, copying a thousand photos between computers takes just five seconds. And copying a two-minute HD video from a camera to another device takes just three seconds (compared to 60 seconds using Wi-Fi). The WiGig standard is managed by the Wi-Fi Alliance, but isn’t backward-compatible; its aim is to complement Wi-Fi, not supersede it. WirelessHD, meanwhile, is proprietary, offers similar range and performance and targets the same kinds of applications.
The Challenge for Designers and Procurers These are just two examples of new or emerging wireless communication technologies. It’s unclear which, if any, will grow to be as popular as Wi-Fi and Bluetooth for their specific use cases. This makes it a challenging area for product designers and buyers – a feature of a particular technology may enable you to differentiate your product or service, but this will be of little value if the technology you’ve chosen doesn’t achieve mass-market penetration. Equally, when you’re buying new systems, they’re unlikely to function in isolation, so it’s critical you think about interoperability with any existing or future systems you may use.