One of the problems with getting higher speeds to work in such a setup has been the low cut-off frequency of the modulation (RTD oscillator) at 1.5GHz, which limits the speed to a maximum of 3Gbps. But the team were able to go much faster by cutting out the “parasitic components” of the RTD and improving the cut-off frequency to 15GHz.
Crucially the new setup would work at room temperature and the device size could be made much smaller, which might make using THz frequencies in Smartphones’ a realistic option. Speeds of 1 Terabits per second or faster, over a range of up to 10 metres, are now being targeted.
By comparison the previous XG-PON standard only ensured an asymmetric speed of 10Gbps download and 2.5Gbps upload. Now all we need is computers, Internet services and WiFi networks that can actually harness such performance in the first places.
Mark.JUK writes: A team of researchers working in the Optical Networks Group at the University College London in England claim to have achieved the "greatest information rate ever recorded using a single [coherent optical] receiver", which was able to handle a record data speed of 1.125 Terabits per second (Tbps). The result, which required a 15 sub-carrier 8GBd DP-256QAM super-channel (15 channels of data) and total bandwidth of 121.5GHz, represents an increase of 12.5% relative to the previous record (1Tbps). Now they just need to test it using some long fibre optic cable because optical signals tend to become distorted when they travel over thousands of kilometres.
Mark.JUK writes: A group of Japanese scientists working on a project managed by Hiroshima University claim to have successfully built a TeraHertz (THz) transmitter, which is implemented as a silicon CMOS integrated circuit and can transmit a signal running at 10Gbps per data channel over multiple channels in the 275-305GHz band for a top speed of 100Gbps (Gigabits per second). But crucially nobody has mentioned the distance at which this speed could be achieved, particularly since the THz band isn't likely to have much of a reach. It also sits very close to the region used by lasers.
Mark.JUK writes: Networking equipment manufacturer TP-Link are today claiming a "world's first" after they unveiled their new Talon AD7200 router, which uses the cutting edge 802.11ad Wi-Fi standard (Qualcomm Atheros chipset) in order to deliver Wireless LAN (WLAN) data speeds of up to 4,600 Megabits per second via the unlicensed 60GHz spectrum band. Mind you the limited range and problematic penetration of solid walls at 60GHz might make it less useful in some homes.
Previous trials have used significantly higher frequency bands (e.g. 20-80GHz), which struggle with coverage and penetration through physical objects. By comparison Huawei's network operates in the sub-6GHz frequency band and made use of several new technologies, such as Multi-User MIMO (concurrent connectivity of 24 user devices in the macro-cell environment), Sparse Code Multiple Access (SCMA) and Filtered OFDM (F-OFDM).
Assuming all goes well then Huawei hopes to begin a proper pilot in 2018, with interoperability testing being completed during 2019 and then a commercial launch to follow in 2020. But of course they're not the only team trying to develop a 5G solution.
Mark.JUK writes: Researchers at the University of California in San Diego have demonstrated a way of boosting transmissions over long distance fibre optic cables and removing crosstalk interference, which would mean no more need for expensive electronic regenerators (repeaters) to keep the signal stable. The result could be faster and cheaper networks, especially on long-distance international subsea cables.
The feat was achieved by employing a frequency comb, which acts a bit like a concert conductor; the person responsible for tuning multiple instruments in an orchestra to the same pitch at the beginning of a concert. The comb was used to synchronize the frequency variations of the different streams of optical information (optical carriers) and thus compensate in advance for the crosstalk interference, which could also then be removed.
As a result the team were able to boost the power of their transmission some 20 fold and push data over a “record-breaking” 12,000km (7,400 miles) long fibre optic cable. The data was still intact at the other end and all of this was achieved without using repeaters and by only needing standard amplifiers.
The PoWiFi system could in the future also be adapted to suck energy from different bands (e.g. 900MHz, 5GHz etc.) to further improve its capabilities, although doing so could create some interesting new legal questions and or pose some new security risks (e.g. a Power Denial-of-Service Attack).
The demo also made use of 2×2 Multiple-Input and Multiple-Output (MIMO) links via single carrier Null Cyclic Prefix modulation and frame size of 100 micro seconds, although crucially no information about the distance of this demo transmission has been released and at 73GHz you'd need quite a dense network in order to overcome the problems of high frequency signal coverage and penetration.
The team, which forms part of the UK Government's 5G Innovation Centre, is supported by most of the country's major mobile operators as well as BT, Samsung, Fujitsu, Huawei, the BBC and various other big names in telecoms, media and mobile infrastructure. Apparently the plan is to take the technology outside of the lab for testing between 2016 and 2017, which would be followed by a public demo in early 2018.
In the meantime 5G solutions are still being developed, with most in the early experimental stages, by various different teams around the world. Few anticipate a commercial deployment happening before 2020 and we’re still a long way from even defining the necessary standard.
At present BT already covers most of the UK with hybrid Fibre-to-the-Cabinet (FTTC) technology, which delivers download speeds of up to 80Mbps by running a fibre optic cable to a local street cabinet and then using VDSL2 over the remaining copper line from the cabinet to homes. G.fast follows a similar principal, but it brings the fibre optic cable even closer to homes (often by installing smaller remote nodes on telegraph poles) and uses more radio spectrum (17-106MHz) over a shorter remaining run of copper cable (ideally less than 250 metres).
The reliance upon copper cable means that the real-world speeds for some, such as those living furthest away from the remote nodes, will probably struggle to match up to BT’s claims. Never the less many telecoms operators see this as being a more cost effective approach to broadband than deploying a pure fibre optic / Fibre-to-the-Home (FTTH) network.
Mark.JUK writes: A new project called TWEETHER, which is funded by Europe's Horizon 2020 programme, has been setup at Lancaster University (England) with the goal of harnessing the millimetre wave (mmW) radio spectrum (specifically 92-95GHz) in order to deploy a new Point to Multipoint wireless broadband technology that could deliver peak capacity of up to 10Gbps (Gigabits per second). The technology will take 3 years to develop and is expected to help support future 5G based Mobile Broadband networks.
Mark.JUK writes: Samsung has successfully become the first to demonstrate a future 5G mobile network running at speeds of 7.5Gbps (Gigabits per second) in a stationary outdoor environment, but to cap that achievement off they also delivered 1.2Gbps while using the same technology and driving around a 4.3km long race track at speeds of up to 110Kph.
Crucially the test was run using the 28GHz radio spectrum band, which ordinarily wouldn't be much good for mobile networks where wide coverage and wall penetration is an important requirement. But Samsung claims it can mitigate at least some of that by harnessing the latest Hybrid Adaptive Array Technology (HAAT), which uses millimeter wave frequency bands to enable the use of higher frequencies over greater distances.
Several companies are competing to develop the first 5G technologies, although consumers aren't expected to see related services until 2020 at the earliest.