Tomorrow's wireless

Every year, the National Instruments (NI) Technical Symposium offers an insight into the latest innovations in the areas of test, measurement and control.

At the 2016 symposium, held in Sydney on 17 November, attendees were presented with an overview of how 5G and the Internet of Things (IoT) are changing the future of wireless.

Jeremy Taylor, area sales manager for NI, explained that standards bodies are currently putting together some of the standards that will form what everybody knows as 5G. These standards will differ across the three main use cases of 5G — that is, the three main ways in which it will be utilised:

• Enhanced mobile broadband — requiring high data throughput, in the order of 10 Gbps or higher, to allow for fast video download and for virtual reality technologies.
• Massive machine-type communication (mMTC) — requiring the ability to handle dense networks of devices, in order to increase the number of devices available to a network.
• Ultrareliable machine-type communication (uMTC) — requiring low latency and high reliability, for applications where vehicles are talking to each other and to infrastructure.

Different 5G applications will have different requirements, said Taylor, “whether you’re dealing with vehicles or transportation systems, in manufacturing, industrial automation, energy or health care”. 5G researchers therefore need to develop the right capabilities for each application, and the technologies to support these capabilities.

But what exactly is 5G? Professor Jinhong Yuan, from UNSW’s School of Electrical Engineering and Telecommunications, set out to explain the differences between 5G and 4G, noting that some people may think their 4G mobile phone has all the power they need.

“People may say that 4G is faster than 3G, 3G is faster than 2G, so 5G will be better than 4G for sure,” said Professor Yuan. But not only is 5G faster than 4G, he said — it is also more reliable, with low latency (1 ms) and high capacity, making it suitable for mMTC and crucial for mission-critical applications.

“Here’s an example,” he said. “If a doctor wants to use the internet to do a remote operation, you really need to have a critical 1 millisecond delay.”

Professor Yuan also stressed the efficiency of 5G technology, which he claimed is more important than speed. He noted that telco companies only ever advertise their peak data rates, failing to mention that these rates are substantially reduced if a network is being accessed by multiple users.

“20 gigabits [per second] doesn’t mean everyone will get it,” he said. “As a peak point, if you are the only user there, you will get it. If lots of people are there, everybody will have to share that peak data rate.”

The advantage of 5G, said Professor Yuan, is that efficiency will be tripled, so while this peak data rate is still unlikely to be reached in a high-capacity environment, user experience will certainly be improved compared to today’s standards.

Connecting all the devices in a single building is one thing, but as Professor Yuan explained, massive machine-type communication is quite another. mMTC refers to the connection of one million devices over 1 km², which means a new approach to connection will be required. And according to Professor Yuan, the future lies in random access.

“[With] a traditional, one-way standard packet, you have a big packet,” said Professor Yuan. In the future, he said, your device may send only a little bit of data at a time — 1 to 2 bytes — so it will require the ability to carry out short-packet transmissions. This is currently achieved using a protocol called ALOHA, which is typically implemented in environments with large numbers of users.

“Everyone, if they want to transmit, can only transmit a very short packet,” said Professor Yuan. “So what you do is that you transmit randomly. If the receiver can receive it, you are successful. Otherwise, after a while you retransmit.

“You can see this kind of protocol is easy to implement, but the problem is that if two users of the system simultaneously attempt transmission, you will have collision. Due to this collision, you need to retransmit. So the efficiency for this protocol is only 18%. You can think about it in such a way that there are 100 people in this room and everybody wants to transmit something, but only 18 people can get their data through the network.”

Seeking a solution, Professor Yuan and his colleagues developed a more coordinated approach that involves a series of timeslots.

“If you want to transmit, you only transmit during a particular timeslot,” he said. “You have no collisions… so eventually you can double the throughput compared to ALOHA. That means of 100 people trying to transmit, you can have 37 people successful.”

He and his fellow researchers then went one step further, working to improve ALOHA with a methodology called coded slotted ALOHA — a system that works very similar to ALOHA, except instead of having one timeslot in which to transmit your data, you get two.

“If everybody transmits twice, chances are that you may have one of your packets without a collision,” said Professor Yuan. “If your packet doesn’t have a collision, you can get it through… At the end of the day, you can improve the throughput from 37% to 91%.”

This is just one example of a technology that has been developed to cope with the demands of 5G, but there will be many more. According to Taylor, these technologies may include massive MIMO and millimetre-wave communications to deliver high-throughput and high network efficiencies; multiradio access technologies to improve bandwidth utilisation; and new networking technologies, like cloud radio access networks, to reduce the operating costs of networks by centralising baseband processing.

So when can we expect to see 5G networks in the general market? According to the various standards bodies, it won’t be until 2020, though Taylor says this is “closer than you might have expected”. In the meantime, standards bodies and researchers are working relentlessly so that when tomorrow’s wireless technology arrives, we will be ready for it.

Image credit: ©thampapon1/Dollar Photo Club