by Monica Alleven
Ever since the days of 2G, the wireless industry has not been shy about adding more "Gs" to the lexicon.
When the industry moved from GSM to GPRS, it was common to hear references to "2.5G," and when EDGE came around, some people referred to it as "2.75G." A similar pattern emerged during the 3G transition, with UMTS followed by HSPA and HSPA+. Sticklers for standards can argue that LTE is not exactly 4G, but that marketing train left the building a long time ago, and pretty much everyone now equates LTE and/or LTE-Advanced with the 4G term.
Now that the industry is talking about 5G and is in the relatively early stages of defining it, that leads one to wonder: Will there be a "4.5G?"
Hardware/software supplier Huawei has tooted the 4.5G horn pretty heavily, but rival vendors may not be crazy about jumping on that bandwagon. Yet having a shorthand way of referring to a certain technology or set of technologies in a half-G kind of way can come in handy.
Ovum analyst and Fierce contributor Daryl Schoolar says 4.5G really equates to LTE-Advanced, but people are talking about it differently because LTE-A is more or less defined by two-carrier aggregation--that's what people immediately think of when the subject of LTE-Advanced comes up. In part, 4.5G may be viewed as a marketing spin but it's also to educate carriers that there's a lot more to LTE-A than carrier aggregation, such as 4x4 MIMO, three-carrier aggregation, coordinated multipoint (CoMP), LTE-Machine (LTE-M), LTE-Unlicensed and things like that.
Other terms have been used, like LTE Evolved, but "I think 4.5G is probably the best one," he said, adding that 4.5G is really a stepping stone to 5G. "It is a smorgasbord of things" and using a term like 4.5G says "there's a lot more stuff you can do with LTE before 5G gets here." Places like South Korea in many ways need it more and are deploying it more because they're further along in LTE, he added.
Peter Jarich, vice president of consumer services and service provider infrastructure at Current Analysis and a Fierce contributor, recently presented the "What is 4.5G" question in the form of a multiple choice quiz, with the following options for answers: (a) the wireless technologies between 4G and 5G; (b) 3GPP R12/13 enhancements to LTE Advanced (LTE-A); (c) a collection of LTE-A technologies including tighter cellular/Wi-Fi integration, device-to-device communications, massive carrier aggregation, new modulation schemes, and virtualization; (d) all of the above. Of course, in this case, (d) gets you the answer.
Speed, latency addressed
For Huawei, 4.5G sits in between LTE-A deployments, which are ongoing in dozens of carrier networks now, and 5G, which many industry analysts and experts do not think will be commercially deployed until 2020. Huawei, which has announced plans to launch 4.5G commercially in 2016, says 4.5G networks will support latency rates of around 10 milliseconds, peak downlink speeds of around 6 Gbps, and the ability to support 100,000 connections within a single square kilometer.
While Huawei talks about 4.5G, Chinese rival ZTE has been talking about "pre5G," which uses some key 5G technologies while being provisioned over existing 4G user equipment. Of course, pre5G will become available much earlier than 5G and deliver a user experience comparable to 5G, offering high throughput and low latency.
Ericsson has equated Licensed Assisted Access (LAA) with 4.5G. "LAA's incremental use of higher frequency 5 GHz spectrum on small cells, and its harmonization of licensed and unlicensed bands echo key 5G radio access focus areas, perhaps marking the beginning of the 4.5G era," wrote Ericsson's Thomas Cheng in a blog post earlier this year.
"Expect 4.5G features and functionalities" to be in Release 13 and 14, said Hossam Hmimy, senior director, Mobile Networks and Technology Strategy at Ericsson, via email with FierceWirelessTech. LTE-A started with Release 10 and continues on. There are evolutions beyond Release 12, which includes machine-type communication (MTC) and enhancements to reduce power consumption.
A lot of the drive for 4.5G seems to come from the machine-to-machine and Internet of Things (IoT) push. It's important to address and deploy machine-type communications features in LTE networks, Hmimy said. Mobile operators can enhance the data rates in their LTE networks, especially indoors, when carrier aggregating the LTE-U with a licensed LTE band when needed with almost no impact on other systems in the unlicensed 5 GHz band, he said.
Not everyone is on board
Some vendors are not keen on using the term "4.5G." Alcatel-Lucent, which is in the process of being acquired by Nokia Networks for $16.6 billion, doesn't use the term 4.5G because it is not an official part of the standards used by the industry. "Alcatel-Lucent develops products today that are within the 4G area of standards and is actively working to set the specifications of what 5G network architectures will be in the future," a spokesman said.
LTE-Advanced comes post-Release 10, so carrier aggregation, LTE-Unlicensed (LTE-U), LAA, et cetera are all considered part of LTE-A, he said.
Asked if LTE-U/LAA falls into the area of 4.5G, Nokia Networks' CTO for North America, Mike Murphy, said Nokia doesn't use the 4.5G term either and "can only speculate" what it refers to beyond the original LTE baseline definition.
LTE-U extends both LTE and LTE-A to include the use of unlicensed spectrum. "Colloquially, we generally think of LTE-A today largely equating to carrier aggregation, where two or more carriers are combined to provide higher peak rates and capacity for users," Murphy said. However, there are other features of LTE-A as well, so then it becomes easy to understand that LTE-U can apply to both LTE and LTE-A.
'Trailblazing' to 5G
Qualcomm also said it doesn't use the term "4.5G," but its engineers believe Phase 3--referring to Release 13 and beyond--will deliver many new, transformative technologies that will drive an important next chapter of LTE Advanced, trailblazing the path to 5G.
"We envision 5G as much more than faster peak rates and new spectrum, building upon this vision of connecting new industries, enabling new services, and empowering new user experiences," said Rasmus Hellberg, senior director of technical marketing, and Matt Branda, staff manager of technical marketing at Qualcomm Technologies.
Release 12 is just being finalized and expected to be commercialized next year. Release 13 is expected to be commercialized in 2017 and beyond. Qualcomm isn't talking publicly about any Release 13 products, but says it is leading in many of the new expansion areas for 4G that are being introduced ahead of Release 13, such as LTE Broadcast, LTE-U and LTE Direct.
As for the nonbelievers, if there were such a thing as 4.5G--playing along here--how would that differ from 4G or 5G? Nokia's Murphy said 5G is quite distinct. Its formal definition comes in 3GPP standards R14 and R15, which are expected to be complete around the 2017 and 2019 time frame, respectively.
That being said, there are several items that are not "generation dependent" that are being developed today by vendors, he noted. For example, cloud computing for the core network is being worked on today and does not depend on 3GPP.
Regardless of what you call it--"4.5G" or merely a step closer to 5G--it's clear that no one's stopping with 4G.