No sales person in wireless products would have to struggle to find the first line of their pitch – it would simply be "no cables". That, of course, is the core selling point of wireless technologies; they free us from tethering our devices to cables to communicate, transfer data or listen to music. In many products, wireless technology has struggled to reach its true market potential due in part to poorer performance than its wired counter parts. That has changed lately as WiFi speeds compete with wired Ethernet and products such as Wireless headphones are shipped with similar sound reproduction to wired headphones.
A technique which has led to some of the greatest improvements in wireless communications of late is called Multiple-Input Multiple-Output (MIMO). MIMO uses multiple transmitters and receivers to transfer more data at the same time. To use MIMO, either the mobile device or the access point needs to support MIMO but for optimal performance and range, both the station and the AP must support MIMO. It takes advantage of a natural radio-wave phenomenon called multipath where signals bounce off walls and other objects and reach the receiving antenna multiple times via different angles and at slightly different times. This traditionally interfered with a signal but MIMO actually takes advantage of this by using multiple, smart transmitters and receivers with an added spatial dimension, to increase the overall performance and range. It really is a fascinating technology and it is expected that our future 5G rollouts will build on MIMO technology in the small deployed cells.
The wireless communications world can be difficult to navigate with so many seemingly competing standards but in actuality, what you have are products aimed specifically at being a best fit solution in an application niche. WiFi (IEEE 802.11) is good at connecting to the Internet in a relatively confined space using wireless broadband routers. Bluetooth (IEEE 802.15.1) creates personal area networks for devices such as hands-free headsets, keyboards, mice and headphones so that we do not have to reach for cables. It is not as fast as WiFi but it is sufficient to allow those devices to communicate effectively with a paired device. Zigbee (IEEE 802.15.4) creates personal area networks with small, low-power digital radios. It is ideal for wireless light switches, electrical meters with in-home-displays, field sensors, traffic management systems, and other systems that require short-range low-rate wireless data transfer. There are many more proprietary based and open standards all aiming to balance a spectrum of requirements.
The newest kid on the block is Li-Fi. Light Fidelity (Li-Fi ) is a bidirectional, high speed and fully networked wireless communication technology which uses a form of visible light communication. It has been measured to be about 100 times faster than some WiFi implementations, reaching speeds of 224 gigabits per second. One manufacturer seeing these speeds is Oledcomm. The fact that it uses visible light communication (instead of radio frequency waves) allows it to carry more information than a competing RF technology like WiFi.
It is a recent invention coming from Harald Haas at the University of Edinburgh, UK. It uses light from light-emitting diodes (LEDs) to communicate. It works by switching the current to the LEDs off and on at a very high rate (too quick to be noticed by the human eye). A downside is that these light waves cannot penetrate walls which also leads to shorter range but it can be considered more secure from hacking as result of limited spread. It is not limited to line of sight as the light reflected off the walls can still be received. Another advantage is its immunity to electromagnetic interference so it can be safely deployed in aircraft cabins, hospitals and nuclear power plants without causing electromagnetic interference. As the visible light spectrum is 10,000 times larger than the entire radio frequency spectrum, Li-Fi has almost no limitations on capacity. It is also expected to be cheaper than WiFi within a short space of time.
A neat visible light communication system has already been deployed by the Philips lighting company where shoppers using a downloaded app can be located by LEDs thus pinpointing where they are standing and then sending them coupons and information based on their location.
Li-Fi, of course, does not aim to replace all wireless technologies. Bluetooth continues to progress. The latest Bluetooth Smart Ready and Bluetooth Smart standards for instance use improved technology that helps myriad gadgets stay paired longer while using less power. With the rise of gadgets such as fitness trackers, heart rate monitors, medical devices, key fobs and even home lighting controls, the market still exists for Bluetooth.
WiGig (IEEE 802.11ad) is another wireless technology that allows speeds up to 10 times faster than current WiFi. It works at 60 gigahertz and can reach speeds up to 7Gb. It has come about as a collaboration from technology giants such as Apple, Qualcomm, Microsoft and Sony. It is a technology that will also be used to hook computers up to displays and projectors as well as connect to the Internet. Currently there are only a few WiGig products available, but that should change in the months ahead. Intel and others are bringing laptops to the market which support it later this year. Qualcomm's Snapdragon mobile processor can already support WiGig. Not only can it support more data bits in transit but it should be more reliable than WiFi and reduce network congestion as it is in a different part of the frequency spectrum than existing WiFi products. Part of this improvement comes from the fact that it uses an array of tens of tiny antennas to point a beam toward a communicating device as opposed to WiFi's omni-directional output in all directions. One immediate use for it will be transmitting high definition video from smartphones to high-definition TVs or the Internet. WiGig technology can make it possible to transfer a full-length HD movie in under three minutes. It also has the potential to extend the capacity of cellular networks and has already been shown to provide high-speed links at distances of 100 meters or more outdoors. Google have also tested it as a cable replacement technology inside large data centres. We can also expect it to become faster in time. WiGig is not perfect however. It turns out that the 60-gigahertz signals are blocked by walls, ceilings, and floors so for now it is aimed at devices communicating within the same room. In 2016, TP-Link unveiled the world's first WiGig router which also supports the usual 2.4GHz and 5GHz WiFi protocols. The idea is that when you are in range for WiGig, it will use WiGig and failing that it will fall back to the slower links WiFi. The Talon is capable of up to 800Mbps on 2.4GHz, 1733Mbps on 5GHz, and 4600Mbps on WiGig.
There are other exciting technologies too, such as Facebook's extremely high-frequency millimetre-wave band technology. This operates in the 30 to 300GHz spectrum and is typically set up as a "mesh" network, where signals can be bounced between strategically placed antennas. It requires a direct line of sight. So for now, it is safe to say that much work is going on in the wireless space – and we can rest assured that the technology will only get better.
Dr Kevin Curran, senior member, IEEE
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