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5G New Radio: The technical background

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Although 5G is being heavily marketed as a new technology, it’s neither particularly new nor a single technology. If mobile technology were a long-running TV series, 5G is a mid-season reboot, with new characters introduced alongside the old, new plot arcs complementing existing storylines, and a publicity drive that rather overstates the case. However, the possibilities for future development are much enhanced.

There have been three major new generations of mobile technology: 2G replaced analogue with digital; 3G began the switch to data-centric networking; and 4G completed that move. 5G has three main focuses — mobile networking, IoT, and very high-performance industrial control — of which mobile networking will be the most important for most people over the next few years, and which is best thought of as a continuation of 4G’s Long Term Evolution (LTE) under a new flag. Indeed, this stage of 5G is known as NSA (Non Stand Alone) as it will run alongside and interoperate with existing LTE networks. SA (Stand Alone) comes later.

Which is not to say that there aren’t significant innovations in 5G. While the 5G standardisation process covers core network and base station topology as well as other aspects of running high-performance networks, most of the factors that will affect our first experiences of 5G are affected by the subset of standards called New Radio, or 5G NR. Although work on NR was only started in the spring of 2016, it quickly rolled up the until-then very disparate research area and has already produced a number of nearly-there pre-standard references (see boxout below).


15, that difficult stage…

5G NR is developed by a group called 3GPP, the 3G Partnership Project, and the first version of the standard is called Release 15. 3GPP is so called because it was first formed to standardise 3G; it has considerable authority as an international group that brings together standards committees, regulators and industry bodies, and the legal issues over renaming it were too onerous when 4G came along. Release 15 is the 18th major standard, which fact is an excellent indicator of how organisations at this level actually work.

Release 15 has been produced at some speed. Starting in early 2016, a preliminary release in March 2018 was declared complete enough for manufacturers to start preliminary production, By the third quarter of 2018, both Ericsson and Huawei said they’d deployed more than 10,000 base stations on that release. A further standard update appeared in September, with a ‘feature freeze’ final pre-standard version of Release 15 promised for December. However, chips developed by Qualcomm to the September release were reported by industry site Light Reading to have proved incompatible with the March-release-based base stations, potentially requiring a hardware swap.

A three-month delay in finalising 3GPP’s Rel 15 standard (phase 1 of 5G) has resulted in a knock-on delay to Rel 16 (phase 2 of 5G).


Image: 3GPP

As a result the December freeze has been postponed to March 2019 with knock-on delays for Release 16, which is expected to bring the low-latency and high-speed aspects of 5G to prominence. The difficulties, according to 3GPP, were caused by a lack of communication between the technical subgroups working on the Radio Access Network side, those defining the overall system configuration, and those in charge of the core network configuration. Citing overwhelming workloads, the 3GPP said that there had been no time for a coordination meeting of all the subgroups prior to the September release.

The industry is sympathetic, with players like Samsung saying that they’re not changing their roll-out plans. Samsung is expected to show a 28GHz-enabled 5G handset at Mobile World Congress in February 2019.


5G NR includes major advances over LTE, each with specific benefits.

Spectrum

Most importantly, there’s masses of new airspace. 5G NR includes millimetre-wave (mmWave) spectrum (>24GHz) for the first time, with the first release of 5G including frequencies from below 1GHz up to 52.6GHz. The high-frequency spectrum (> 6GHz) comes in many different bands that vary by region, as well as many that are not yet fully available due to existing services that must be closed or moved.

5g-spectrum-bands-worldwide.png

Different spectrum bands are being made available for 5G NR around the world, on different timescales.


Image: Ericsson

The high-band allocations can support very high data rates and intensive frequency reuse, providing very dense, high-performance networking. They have very limited range for a given transmission power compared to lower bands and more stringent health and safety limits, and they are more susceptible to environmental issues like heavy rainfall and seasonal leaf growth. Conversely, the very small wavelength makes it much easier to build very high-performance antennas of small physical size.  

The high bands will be used to overlay existing LTE networks, providing much higher bandwidth on demand to reduce LTE (and eventually, 5G) mid- and low-band congestion, as well as fibre-speed home and office fixed wireless access (FWA) broadband. The 28GHz bands have seen the most attention, with the UK breakdown by region and operator being typical of how a territory already well-serviced with LTE will allocate resources:

5g-ofcom-28ghz.png

Image: Ofcom

Ultra-lean design

Ultra-lean design is a key 5G NR design principle, reducing energy consumption and interference. LTE relies on a number of always-on signals transmitted by base stations — beacons that show which cells are available, reference channels that terminals and base stations use to configure data links, command channels for tracking mobility and so on. In LTE, these signals don’t take up a significant percentage of the overall channel usage, but 5G will have a much denser network with more cells, which will on average have quite a low actual usage rate. The always-on signals will thus take a greater percentage of power, and will interfere more with adjacent cells, leading to lower throughput.

Wherever possible 5G reduces or switches off such signals until they’re actually needed. The reference signal, for example, is only transmitted once data transfer is under way. This means the handset and base station have to optimise the signal on the fly, but the overall benefit to throughput for the network is notable.

Ultra-lean design is also a key component of forward compatibility, a specific requirement in 5G NR for curiously unspecific ends. The basic rule is to leave as much room as possible in implementations to allow future developments. In practice, this means minimising non-data carrying transmissions (reducing overall interference and spectrum use), having a high degree of frequency and time-domain flexibility in 5G designs, and providing paths for reconfiguration in the future both in the hardware and in the specification itself.

This latter decision came about through experience with LTE, which encodes a number of design decisions in the specification such as when and where error-correction happens: if a new service finds these decisions inefficient or even disabling, then there’s nothing that can be done. A reconfigurable standard can improve on old decisions. Also, new basic technologies such as software-defined radio (SDR) have moved much radio engineering from hardware into software, meaning that changing operating characteristics in ways that once took a complete hardware revision can now be pushed out as a software update. 5G is the first generation to fully embrace this.

Modulation and framing

5G modulation and framing is also an increment from existing ideas, but a significant one. Like LTE (and recent wi-fi standards, and just about every modern digital wireless system), 5G NR uses ODFM as its underlying modulation scheme. ODFM (orthogonal frequency division multiplexing) combines multiple subchannels within a channel, and is known to be both robust against interference and efficient in its use of frequencies. It’s also highly flexible, as different numbers of subcarriers can be added to increase a channel capacity, or numbers reduced to provide much lower-power, lower-bandwidth options.

5G NR can choose subcarrier spacing from 15kHz to 240kHz, with a maximum 3300 subcarriers in simultaneous use on one channel. However, channels can be no more than 400MHz wide. The standard is frequency agnostic, meaning any subcarrier configuration can be used on any band. In practice, the mid- and low-band frequencies below 6GHz have markedly different channel and noise characteristics, as well as different maximum bandwidths, to the high-band allocations, so will use 15 to 60kHz channel spacing, while high-band will use 60 to 120kHz. There are currently no 5G band allocations between 6GHz and 24.25GHz, but the standard allows for optimal ODFM configuration to match any future expansion into this spectrum.

5g-odfm-schemes.png

5G ODFM usage models, channel bandwidths and subcarrier spacing.


Image: Qualcomm

Not all devices on 5G NR have to support all bandwidths, which is a change from LTE. Furthermore, 5G NR supports adaptive bandwidth, letting devices move to a low-bandwidth, low-power configuration when appropriate, and gearing up to higher bandwidths only when necessary. This creates the opportunity for very low average power devices that can still deliver high performance — IoT networks, for example, which normally only need small amounts of data for telemetry, but nevertheless need to be able to update their firmware for security and feature patches. The 5G NR specification refers to these different configurations as ‘bandwidth parts’, and in theory a device can support multiple bandwidth parts simultaneously on the same channel, although the first 5G NR release limits devices to one bandwidth part at a time.

Within a subchannel, data is divided up into frames of ten milliseconds each, further subdivided into ten 1ms subframes. Those subframes are themselves divided into slots of 14 OFDM symbols apiece. Thus, wider bandwidth subchannels have more OFDM symbols per second and each slot thus gets shorter, but the basic frame structure stays the same. At the lowest subcarrier spacing, 15kHz, the frames are identical to LTE, simplifying compatibility.

LTE and similar systems allocate bandwidth to different devices by slot, but 5G NR has a mechanism for a transmission to start within a slot, effectively creating what are called ‘mini-slots’. This is especially useful for the high bands, which can have very large OFDM symbols and thus the ability to use just a few to carry a relatively short message improves both channel reuse and latency. Another potential advantage is if, or when, 5G expands to unlicensed spectrum, which normally comes with a ‘listen before use’ rule to prevent interference. If a channel appears quiet, the ability to start a transmission without having to wait for a slot boundary reduces the chance of another device grabbing the channel.

Other low-latency adaptations in 5G NR are tight requirements for data transmissions to start after a channel is granted, and restrictions on processing delay for data streams. This is achieved in the higher network layers by changing header structures so that processing can begin without the full packet information being known, and at the physical layer by having the radio receive essential information from reference and downlink control signals instead of deriving it from the symbol stream.

Beamforming

5G NR has a much more advanced concept of beamforming than LTE. Beamforming is the manipulation of the signals fed to and received from complex antennas to create beams in space that focus power in a particular direction. LTE could do this for data; 5G NR extends this to control channels too, while increasing the precision and adaptability overall for operation under different conditions. At the high bands, beamforming will mostly be used to increase range by energy focus, while at the mid and low bands below 6GHz, where attenuation is less of a problem, beamforming will be a key part of MIMO, the multiple-in multiple-out spatial channel technique that increases bandwidth for multiple devices in the same area. Although not part of the first release, 5G NR will support distributed-MIMO, where a user can receive different parts of the same data stream from multiple sites.

5g-beamforming.png

With FD-MIMO, the antenna system can form beams in both horizontal and vertical directions, giving coverage in 3D spaces.


Image: Sharetechnote.com

This touches on the other major areas of 5G beyond the radio: how base stations communicate with each other and with the core network, how the operators manage the whole system for reliability and profit, and what shapes the new network uses built on the back of these technologies will take. Don’t expect the full picture to become clear for three to five years: 5G in 2019 will be as much about groundwork as immediate results.

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Toyota GR010 Hybrid racer rumored to spawn a street version

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Toyota has a new racing car for the 2021 FIA World Endurance Championship. The vehicle is called the GR010 Hybrid and what’s more exciting than a new racing car is that reports claim a street-legal version will launch in the near future. The vehicle seen below is the 2021 GR010 Hybrid racing car, but it’s unclear what exactly the street-legal version might look like.

The racing car was built to meet the WEC series regulations, which only allow a single configuration. To perform at its peak on both low and high downforce tracks, the vehicle has an adjustable rear wing. Toyota does warn that the GR010 Hybrid will be slower than the TS050 racing car that it replaces.

The reason it will be slower has to do with regulations for the racing series. Toyota was forced to make the GR010 357 pounds heavier and 32 percent less powerful than the TS050 it’s replacing. The GR010 Hybrid is also nearly 10-inches longer, 4-inches higher, and 4-inches wider than its predecessor.

Toyota expects it will be about ten seconds slower at Le Mans than the TS050. Ten seconds is an eternity on a race track. Development took 18 months, and the car uses a gas-electric powertrain. The gas engine is a 3.5-liter V6 that makes 670 horsepower sent to the rear wheels. The front wheels get 268 horsepower from an electric motor-generator.

The total output is 938 horsepower. However, for WEC racing, total power is limited to 670 horsepower. We hope to learn more details about the street version of the car soon. The first race for the racing version will happen on March 19 at Sebring. Le Mas will occur on June 12, and the car will participate in other events during the season.

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Some Ford Mustang Mach-E deliveries have been delayed

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Ford has officially confirmed that it is delaying the delivery of hundreds of Mach-E electric vehicles to perform additional quality checks. A very limited number of Mach-E electric vehicles were delivered late last year. With Ford saying it was delaying deliveries to perform additional quality checks after delivering those vehicles last year, it’s easy to wonder if the owners of those vehicles discovered some issues.

Ford says that it is performing additional quality checks on several hundred Mach-E models built before dealer shipments started last month. The automaker says it wants to ensure the EV’s meet the quality customers expect and deserve. Ford took a beating on the new Ford Explorer’s launch when the vehicle launched with some significant issues that delayed deliveries.

Ford doesn’t want vehicles with issues to get into the hands of buyers again. Ford hasn’t confirmed an issue with the Mach-E, but it would seem odd to stop deliveries and conduct additional quality checks if there wasn’t some sort of suspicion of a problem with the quality of the vehicles.

It may simply be that Ford wants its new electric vehicle to be perfect. The delay could be something as small as checking body panels to be sure they’re appropriately aligned. There were some rumors that the EV didn’t charge as fast as expected, but it’s unclear if the checks have anything to do with the charging system.

We were able to spend some quality time hands-on driving the 2021 Mach-E last month. Anyone wanting more details on Ford’s new electric vehicle should check out our hands-on. Ford has a lot riding on this vehicle, and if it wants to compete with Tesla and other big names in the automotive market, it needs to get things right. Delays are certainly better than delivering vehicles that don’t meet expectations.

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2021 Chevrolet Trailblazer Review – A very rational compact crossover

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Times are tough if you’re in the market for a brand new all-wheel drive crossover on a severe budget, but the 2021 Chevrolet Trailblazer thinks it has the answer. Cheapest model in Chevy’s SUV line-up, its sticker price isn’t quite that attention-grabbing $19k by the time you add AWD, but even then it still won’t break the bank – just as long as you’re willing to put up with the Trailblazer’s compromises to get there.

As you’d expect, the Trailblazer owes many of its styling cues to the larger Blazer SUV. The proportions look more muscular and intentional than the overall dimensions would suggest, particularly the squinting headlamps atop a gaping lower front grille. The Midnight Blue Metallic of my test car wasn’t the most flattering shade, mind: brighter colors help emphasize the contrast sections, like the chrome and the chunky cladding.

In displacement-obsessed America, the Trailblazer’s 1.3-liter turbocharged three-cylinder engine is a kooky outlier: it’s easy to forget that, over in Europe and Asia, squeezing more out of thriftier sippings of gas has been the status-quo for many years now. Chevy’s three-pot gets you 155 horsepower and 174 lb-ft of torque, but the biggest surprise is that it’s actually the larger of the two engines the Trailblazer can be had with.

Standard is an even smaller 1.2-liter turbo, coaxing 137 horsepower and 162 lb-ft of torque from its three cylinders. It uses a continuously variable transmission (CVT), unlike the 1.3-liter with its 9-speed automatic. If you want all-wheel drive rather than power to the front wheels alone, you’ll need to cough up the extra for the bigger engine.

The 2021 Trailblazer FWD L starts at just $19,000 (plus $995 destination), making it less than half the average selling price of a new car in America right now. You’ll pay $3,100 more for the Trailblazer AWD LS 1.3L, the first trim offering the punchier engine and all-wheel drive. My review car was the positively-plush (in comparison) Trailblazer AWD LT, at $28,180 with options and destination.

Your money gets you 17-inch high-gloss black alloy wheels, front fog lamps and LED daytime running lights, power-adjusted side mirrors, electric windows, heated front seats, keyless entry and start, OnStar 4G LTE WiFi, a 7-inch infotainment system with wireless Android Auto and Apple CarPlay, and both USB Type-A and Type-C ports plus an aux-in. Safety tech includes lane-keep assistance, forward collision alerts, tire pressure monitoring, and automatic emergency and front pedestrian braking.

The $620 Adaptive Cruise Control package added the smarter cruise, leather wrapping for the shifter and steering wheel, a 4.2-inch color display sandwiched between the analog gauges for the driver, and a rear center armrest. Another $620 added the Convenience package, with single-zone automatic air conditioning, auto dimming for the rearview mirror, a 120V power outlet, SiriusXM, an 8-inch upgrade for the infotainment touchscreen, and rear USB Type-A and -C charging ports.

Finally, $345 throws in rear parking assistance, rear cross traffic alert, and blind spot warnings. There’s no leather option, only a leatherette upgrade from the perfectly satisfactory cloth, and weirdly no wireless charging pad available, strange since Chevy has been ahead of many by embracing wireless smartphone projection. You can even connect two Bluetooth devices simultaneously, which is more than many far more expensive SUVs can manage.

Out on the road, the 1.3-liter engine underwhelms. Acceleration is on the sluggish side, and though urban nippiness is reasonable the Trailblazer starts to feel a little more out of its depth on the highway. Put your foot down to take advantage of a gap in the next lane and there’s a disconcerting absence of grunt as the gearbox hurries to get you back into the power band. On Michigan highways, where a 70 mph limit typically means 80 mph in the slow lane, I held back from openings in faster traffic more often than I would in other small crossovers.

The same reticence appears on more interesting roads, where the Trailblazer fails to bring the fire. Squishy suspension makes some sense when you’re trying to smooth out unruly asphalt – though the short wheelbase and no lack of body roll means rougher sections still make themselves known – but does no favors for enthusiast drivers.

Perhaps, though, that’s asking too much. Economy works in the Trailblazer’s favor, with the 1.3L FWD rated for up to 31 mpg combined by the EPA, and my AWD version for 26 mpg in the city, 30 mpg on the highway, and 29 mpg combined. My mixed driving hit those numbers with no problems. The cabin design is unmemorable, with swathes of different tone plastic failing to lift what’s a generally dark interior, but it at least feels decently screwed-together and spacious.

25.3 cu-ft of cargo space with the rear seats up expands to 54.4 cu-ft with them down. Honda’s HR-V has more; Nissan’s Kicks has less. What the Chevy gets that neither rival offers is a folding front passenger seat, opening almost the full length of the cabin for hauling longer items. The HR-V and Trailblazer have more legroom in the rear than the Kicks does, too.

I don’t dislike the 2021 Trailblazer, I just struggle to remember it. The idea of a smaller, peppier version of the Blazer isn’t a bad one, and Chevrolet’s styling has some good angles, it’s just that this compact crossover doesn’t really go far enough in any direction to stand out of the crowd. Mazda’s CX-30 is in the same ballpark for price as this LT trim, but looks and drives so much better. The Trailblazer brings more practicality and cargo space to the party, but I know which I’d rather look outside and see parked on my driveway.

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