Massive MIMO Rocks      Back to Wirelessone.news

Massive MIMO Feb 2018

Dark blue: Building actively: China Mobile, Softbank Japan, Bharti India, 
Jio India, Vodafone India, Singtel, Globe Phillippines

Dark green: Announced: DT, FT/Orange, BT, Sprint USA, Qatar, Verizon USA, T-Mobile Netherlands, 

Light green: Talking: Vodafone England, Vodafone Turkey,
Safaricom Kenya, Telekom South Africa   

 

Professor Larsson: New Data Suggest Trouble Ahead for FDD

FDD MIMO test data"TDD (Time Division) Massive MIMO represents the only effective implementation of Massive MIMO at the frequency bands under consideration."!? So says Professor Erik Larssen, a leading researcher at Linkoping University in Sweden. Larsson blogged the controversial paper on April 4, the day after it was published at https://arxiv.org/pdf/1704.00623.pdf. The blog and the abstract of the paper is below. 

On the other hand, China Telecom, China Unicom, Huawei, and ZTE have announced successful trials of FDD (Frequency Division) Massive MIMO. A joint press release by China Telecom and ZTE asserts the opposite: "The FDD Massive MIMO solution is predictable to be deployed in China Telecom in 2017." Obviously, I'm not qualified to judge engineers of that quality when they disagree. I'll do my best to explain the issues and direct you back to the principals. 

The primary issue, as I understand it, is whether FDD overhead is inevitably too high for FDD to be practical. With line of sight (LOS), the two techniques appear to have similar results. Without decent Line of Sight. the new paper reports a significant difference.  

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China Telecom, China Unicom, ZTE, Huawei Plan FDD Massive MIMO

China Unicom MIMO Test"The commercial deployment of FDD - Frequency Domain - Massive MIMO is expected in 2017, including at China Telecom." (All the MM deployed today is TDD - Time Division.) That comment by ZTE is based on tests with China Telecom and China Unicom, both world class telcos. Huawei and ZTE are both shipping TDD gear. ZTE is a top-5 telecom manufacturer. Huawei has grown so much their sales totals and research budget are now more than Ericsson and Nokia combined.

Backing like this is highly credible. The joint press releases are below. I'm always skeptical until I have results from substantial field deployments, but wouldn't have doubted this except for work by Emil Bjornson, Erik Larsson, and Tom Marzetta. Marzetta invented Massive MIMO; Larsson & Bjornson are respected Swedish Professors. 

More than half the spectrum in use is FDD - Frequency Division. Massive MIMO systems in the field today use TDD - Time Division.

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45x Improvement in University Labs for Massive MIMO

Bristol Lund teamBristol and Lund showed what's possible in spectrum below 6 GHz, rather than millimeter wave (below.) That was in May, 2016. In 2017 as I write, production Massive MIMO systems are getting 3x-10 more capacity, a remarkable return for a relatively modest investment. Lund Professor Emil Björnson believes, "20x-40x improvements in spectral efficiency over IMT Advanced are what to expect from Massive MIMO."

Peak speeds in MM shipping systems for 20 MHz typically are > 400 megabits. The universities, working with National Instruments, achieved 145.6 bits/s/Hz on a single 20 MHz radio channel.  Today's single channel LTE systems get 2-4 bits/s/Hz, a small fraction of what Massive can do.

Most systems building today use 60-80 MHz (4 bands.) That would allow speeds of well over a gigabit with multi-band Massive. As far as I know, no one has reported field results for more than 20 MHz on Massive. That should come shortly.

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FDD Massive MIMO: Soon Coming or Serious Issues?

Ten myths one critical question 200Only Massive MIMO in TDD spectrum has gone beyond testing but China Telecom, Sprint, Huawei, and ZTE are confident commercial FDD products are close.  Their press releases about FDD tests are enthusiastic. However, systems based on TDD (Time-division duplexing,) are deploying by the hundreds and soon by the thousands, but FDD (Frequency-Division duplexing) systems are just in early testing. The choice between FDD and TDD is driven by spectrum availability. The majority of spectrum in use is FDD.

Massive MIMO requires constantly updated Customer State Information (CSI.) The cell needs constantly updated receiver location and capability to steer the many antennas. The overhead is considerable, possibly too high to use FDD in many places. FDD systems appear to have lower capacity but there is almost no data from the field. 

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8 Antennas Double Capacity at VIVA in Kuwait

huawei viva4x4 MIMO is sweeping the world and 64 antennas Massive MIMO is starting to deploy by the thousand. Huawei also offers a middle ground: Eight antennas.  They work with ordinary phones that only have two antennas. That's a big advantage since phones with four antennas are just hitting the market and won't be common for several years.

The eight antenna improvement over 2x2 is "almost double" according to Zarrar Khan, CTO of Kuwait VIVA, a rapidly growing telco controlled by Saudi Telecom. It offers significantly more capacity than 4x4 rigs. In comparison, Huawei reports 4x4 testing by MTN, the South African giant, improves downlink improvement of 74% and uplink 39%.

Important caveat: MIMO results are drastically different depending on the terrain. 

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Massive MIMO - The Unanswered Questions

Massive MIMO is the next great step in mobile networks. Huang Yuhong of China Mobile and Hidebumi Kitahara of SoftBank are deploying hundreds of nodes and reporting performance improvements of 2X to 10X. Sprint in the U.S. and 3 in Austria are firmly committed. Gig LTE - 4x4 MIMO, 3/4 band aggregation, and 256 QAM is spreading rapidly in 2017; the next step will be the 64+ antennas and beamforming of Massive MIMO, some at millimeter wave. I had a chance to ask some experts a few questions so put together these. Others welcome.

in 2018-2019, what's a smart Massive MIMO deployment strategy for a network with growing traffic? 

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"10 times!" Sprint's Ottendorfer on Massive MIMO

OttendorferSome places will only be 2-5X. With hundreds and soon thousands of systems in Japan and China, there's no doubt the technology works. SoftBank and China Mobile were first in the world to deploy, Now, Sprint, AT&T, and Verizon are discussing when, not whether. Since Sprint is owned by SoftBank, it was easy to predict they would join in. Mike Dano at Fierce had this story a month ago; now Ottendorfer has filled in the details.

"Massive MIMO – massive volumes of input and output streams – might sound like geek talk – it’s really just the ability with massive computing power to add massive numbers of antennas elements in the antennas on our cell sites. And 3D beamforming supported by Massive MIMO is simply more cell signals moving in both horizontal and vertical directions."

Gig LTE & Massive MIMO will raise capacity on U.S. networks at least 4X and more likely 7-15X in the next few years.

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AT&T Joins the Race to Massive MIMO with 96 Antenna Blue Danube System

Blue Danube antenna 200Field trials underway. mmWave is exciting, drawing headlines, and certainly will be crucial one day. Massive MIMO is here today, deploying by the thousands at China Mobile and Softbank Japan. Verizon's Shamsundar told me last year, "We must have Massive MIMO." The early generation of M-MIMO and mmWave are showing 3X to 5X performance improvements. 50X improvements will be possible, although no one believes that other than a few engineers.

Now, AT&T has confirmed they are in field trials. AT&T has invested in Blue Danube, whose 96 antenna BeamCraft 500, right, is about 5 feet tall. It produced a 2X to 5X improvement in a selected high traffic area. These results are yet more proof of the potency of Massive MIMO. ZTE and Huawei are seeing 3X to 10X improvements from full Massive MIMO systems at Softbank and China Mobile. With eight antennas, Huawei is delivering 1.5X in Kuwait. 

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Austria confirms Massive MIMO for 2017. First in Europe

Austria's Mozart 200"We are planning commercial deployment of Massive MIMO sometime in 2017 (we cannot communicate definite dates yet)." Tom Tesch, Hutchison Drei Austria. Three years ago, Stanford Professor Paulraj told me Massive MIMO was going to produce an enormous capacity boost. It's now coming out of the labs. Every network architect in the world is watching the Massive MIMO at Softbank in Japan and China Mobile. They are getting between 3X and 10X more capacity in the same amount of spectrum and are ordering thousands of systems. I've received so many reports of "tests" I ignore them. I'm now getting committed builds, including Sprint in the U.S.

The press release said "tests" but company spokesman Tesch confirmed to me the decision is made to deploy.

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Marzetta's Fundamentals of Massive MIMO is available

Marzetta book 180This newly published book belongs close at hand for every engineer in advanced wireless. Marzetta invented it at Bell Labs, so I expected a fine book. Marzetta and co-authors Larsson, Yang, and Ngo did an extraordinary job. The book is admirably clear, short, and definitive. They answer the key questions: what it is, why it works, and how to design the systems. The last chapter reviews the problems still to be solved. It's only 160 pages (and 50 more in appendices) but all the main topics are addressed. For depth on a particular topic, the authors point you to the original research. The book is written for engineers; some parts are hard going for a layman. 

The Resources list at the end references the seminal works by Paulraj, Foschini, Alamouti, Goldsmith, and the authors, as well as the 150 other works that have defined the field.

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Doubling speed with 4x4 MIMO & 256 QAM at T-Mobile

4x4 256 Qam 180Just a few consumer tests but they look good. Gig wireless (shared) is behind schedule; Telstra in Australia and SKT in Korea thought they would have it for customers before the end of 2016 but they haven't made it by Xmas. Pieces of the necessary technology are deploying widely. T-Mobile in many places is using four antenna MIMO and 256 QAM advanced coding. They are not bonding 4 channels, which would take peaks to around a gigabit. Sprint is widely bonding three channels and will go to four channels (80 MHz.)

40-50 megabits download (right), two or there times more that without those two improvements (left.) Larger picture below. That's much less than the 200-300 megabits peak, shared, from 20 MHz at the cell tower. Few users get the full 200+ most of the time. However, many will get much higher speeds than they are today. 

Most users will not get close to the peak speed.

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"I am crazy about Massive MIMO," Kitihara of Softbank ordering 1,000's of Massive MIMO bases

Massive MIMO Softbank by Jennie Bourne5G is here. China Mobile and Softbank plan thousands of sites. At Huawei's remarkable Tokyo Mobile BBF, both Softbank Japan and China Mobile showed enthusiasm. These are the first large moves in 5G, pulling Massive MIMO at least one year ahead of high-frequency millimeter wave. I believe my report  was the first in the West. I have since learned that Huawei, as well as ZTE, provided equipment.

Gear that triples capacity (or better) at modest cost is now in production from both Huawei and ZTE. Softbank has 100 base stations up and running. They are mostly in Tokyo but also in several other cities. China Mobile has working systems in two cities.  

Their early reports are that 128 antenna Massive MIMO today increases capacity 3X to 10X. Expect considerably better results over time. MIMO inventor Paulraj of Stanford two decades ago realized that MIMO could enormously increase capacity in a given amount of spectrum. Remarkably, the additional throughput requires minimal additional power.

Respected engineers - Henry Samueli, Andrea Goldsmith, Vint Cerf - two years ago were comfortable with predictions that wireless capacity would soon increase 50X. MIMO is crucial to that goal.

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