Monday 29 November 2021

Huawei MetaAAU Promises Improvement in 5G Network Performance and Energy Efficiency

Huawei's latest Active Antenna Unit, MetaAAU is billed as having loads of improvement and potential. A sponsored article on Light Reading says:

Speaking at the recent Mobile Broadband Forum event in Dubai, Yang Chaobin, president of Huawei Wireless Solution, flagged numerous technology innovations and advances that take the traditional AAU (active antenna unit) found in Massive MIMO onto another level.

MetaAAU, developed by Huawei, incorporates ELAA (extreme large antenna array) technology supporting 384 antenna elements. It’s double the number of a traditional AAU.

“By introducing 384 antennas in the AAU, coverage can be improved by 3dB on both the downlink and the uplink, and the user experience can also be improved by 30%,” said Chaobin, “Energy savings of 30% can also be achieved.”

The Official Huawei press release points out: 

Released in October this year, Huawei's 64T64R MetaAAU is the ideal solution to improve both network performance and energy efficiency using innovative hardware and software. For hardware, MetaAAU introduces the extremely large antenna array (ELAA) which enables 384 antenna elements, double that of a conventional AAU (192). ELAA is combined with ultra-light integrated array and signal direct injection feeding (SDIF) to improve both coverage and integration. For software, MetaAAU utilizes the Adaptive High Resolution (AHR) Turbo algorithm to enable precise, dynamic, and targeted beamforming, significantly improving user experience and cell capacity. This hardware/software combo marks a new breakthrough in Massive MIMO coverage and energy efficiency.

In comparison with conventional 64T64R AAU and 32T32R AAU, MetaAAU improves coverage by 3 dB and 6 dB and user experience metrics by 30% and 60%, respectively. For example, in one of its flagship projects — 5G Capital that brings 5G to every corner of Beijing — China Unicom Beijing is using MetaAAU to add 30% in both uplink and downlink coverage along with 25% better experience among cell edge users.

MetaAAU is also a powerful energy-saving tool. It allows base stations to achieve the same level of coverage for cell edge users but with a lower transmit power, reducing energy consumption by approximately 30% over conventional AAUs. This has also been tested in the 5G Capital project.

With its advantages in energy efficiency and coverage, MetaAAU is slated for success. Going green is now a global objective — for example, 26 CEOs of European ICT companies have committed to combat climate change with the European Green Digital Coalition (EGDC). At the same time, 5G network coverage requirements will only continue to grow, rolling out 5G in rural and urban, outdoor and indoor contexts. Leading next-gen ICTs will be key in delivering on both demands; and Huawei's MetaAAU stands to be part of the innovation portfolio.

Going back to the Light Reading article:

If traditional materials found in antenna dipoles were applied to ELAA, for example, the weight would drastically increase, making it more difficult and expensive to install on cell sites.

Moreover, without miniaturized filters, ELAA dimensions necessarily become much bulkier compared with traditional massive MIMO antenna. Cell-site space is already constrained and operators don’t want to go through the lengthy process of gaining permission to occupy more tower space, which, in turn, increases maintenance costs.

Another challenge is that antenna elements in a traditional RF feeding network architecture are normally connected by cables, which are an inefficient way to transfer signals. If the antenna array doubles to 384 elements, the length of cable – along with the extent of inefficiencies – increases.

Through a series of hardware innovations, however, MetaAAU makes the transition to ELAA feasible and attractive. Using ultra-lite metamaterials, MetaAAU is around the same weight as the original 64T64R massive MIMO AAU. Adoption of Huawei’s compact wave filter also means MetaAAU dimensions do not require more space.

To address hardware energy inefficiencies, Huawei has adopted SDIF (signal direct injection feeding) technology. SDIF replaces cables with a more energy-efficient metal-type structure.

Aside from hardware innovation, MetaAAU introduces an adaptive high-resolution beamforming algorithm, dubbed AHR (Adaptive High Resolution) Turbo. It has various features, which, when combined, not only reduces wasted radiation energy but also cuts down on ‘noise’ that can degrade network performance.

Among the benefits of AHR Turbo is that it enables MetaAAU to generate extremely narrow beams that can precisely latch onto user equipment, as well as boost air-interface efficiencies by allowing beams to dynamically adapt to radio channel

Here is an official video of MetaAAU

Mobile World Live also has an infographic, which is the source for the image on the top. It's available here.

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Monday 15 November 2021

Will Distributed FD-MIMO be next big MIMO Enhancement?

We have looked at MIMO quite a few times in this blog. Back in February we looked at some of the advancements that Samsung and Ericsson had been showing here.

Last year, in a blog post, Samsung talked about Distributed Full Dimension MIMO (FD-MIMO). The key points were:

Around that time, the concept of Massive MIMO was proposed in academic papers. These papers proposed the idea of making the signal dimension at the base station much bigger by using a massive number of antennas such that all inter and intra-cell interference asymptotically go to zero. MU-MIMO performance would be improved significantly with a much lower interference level, therefore leading to capacity gain. It looked promising, but no one knew how to bring it to reality, since arranging 10s or 100s of antenna elements in the conventional way (i.e., in the horizontal plane) would lead to a base station that is longer than a bus, so obviously it was not going to work in a real deployment.  

An important breakthrough came when engineers at Samsung noticed that a concept called Active Antenna Systems (AAS), could be exploited to organize 64 or 128 antennas into a 2D active antenna array that is similar in size with a conventional 4-TX system as shown in the middle portion of Figure 1. Such a system is called a Full Dimension MIMO (FD-MIMO) system. Initial evaluation of the FD-MIMO system coupled with high-order MU-MIMO showed a capacity gain by a factor of 3-4 times for a 64 or 128-TX FD-MIMO compared to a 2-TX LTE system, as was summarized in a 2012 Globecom paper , “Fulfilling the promise of massive MIMO with 2D active antenna array”, and later in a 2013 IEEE magazine paper , “Full-dimension MIMO (FD-MIMO) for next generation cellular technology”. 

Samsung has been actively leading the FD-MIMO standardization process in 3GPP from the beginning, including the 3D channel model study in 2012 that paved the way for subsequent system design, the 4G LTE version of elevation beamforming and the FD-MIMO work from 2014, and more recently the 5G NR-MIMO version of FD-MIMO. Samsung has also been a leader in prototyping and testing the feasibility of the technology and was the first to demonstrate an FD-MIMO system supporting 12 simultaneous MU-MIMO users achieving a record aggregate capacity of > 20 bps/Hz in early 2015. These feasibility study result was later published in a 2017 IEEE JSAC paper , “Full Dimension MIMO (FD-MIMO): demonstrating commercial feasibility”.

Initial system level simulations show that the D-FD-MIMO system achieves up to 2 times cell average throughput gain compared to the FD-MIMO system, lifting both cell capacity as well as average user throughput. Such a cellular system can be flexibly deployed to “blanket” a given geographical area and provide better service for both outdoor and indoor users. 

We have developed a hardware prototype and performed field test to verify the feasibility and the performance gain of the D-FD-MIMO system. In the field test, 3 distributed LEGO MIMO RFUs and 7 UE emulators were used. When the number of active RFUs increased from one to three, the overall throughput improved by about 4 times.

A significant amount of work needs to be done before we can accurately quantify the benefits of the D-FD-MIMO technology, but these initial results are certainly promising and show a great potential for this new breakthrough of the MIMO technology.

Back in 2017, Samsung researchers also wrote a paper on this topic, Distributed FD-MIMO: Cellular Evolution for 5G and Beyond, which is available on arXiv here. Quoting from the paper:

Distributed Full Dimension MIMO (D-FD-MIMO) is an evolution of FD-MIMO. A D-FD-MIMO network assumes a cellular structure, where a cell is served by one BS and each BS is connected with a large number of antenna elements, of which individual elements are spatially distributed in the cell. One or more antenna elements are equipped with a digital port, and the signals transmitted and received from all the antenna elements within one cell are jointly processed to perform high order MU-MIMO operation.

Such a cellular system can be deployed outdoors in a city-wide area to provide service to both outdoor and indoor users. It can also be deployed inside the building to serve indoor users only. It is also suitable for providing service in a highly populated area, such as stadiums, shopping centers and airports, where a large number of the users are densely located.

Concepts relating to D-FD-MIMO includes distributed massive MIMO, CoMP (a.k.a. network MIMO) and distributed antenna systems (DAS). Distributed massive MIMO treats the entire network as one cell, featuring an enormous number of access points distributed over a large area, jointly serving all the users. pCell by Artemis can be seen as an implementation of the distributed massive MIMO albeit with a smaller scale in terms of the number of antennas. CoMP relies on the coordination among a few transmission points from the same or different sites to enhance User Equipment (UE) experience at the cell edge. DAS is initially proposed to improve coverage in an indoor cellular communication system, and is sometimes adopted in outdoor scenarios as well. One configuration for outdoor deployment is to have a few antenna arrays distributed throughout the cell to perform MIMO operations. Another DAS configuration deploys a number of individual antenna elements in a distributed manner in each cell of the network, which is similar to the D-FD-MIMO setting. Different from our system-level simulation approach, the analysis theoretically derives the asymptotic sum capacity when the numbers of UE and antennas in each cell both approach infinity with their ratio fixed, and assuming perfect uplink power control.

You can get the PDF of the paper here.

We have written about the Cell-Free Massive MIMO here and here. One of the realizations of D-FD-MIMO is as shown in Ericsson Radio Stripes. 

Researchers on this topic may also be interested in watching Wireless Future Podcast episode 13 on Distributed and Cell-Free Massive MIMO (embedded below). The description says:

In this episode, Erik G. Larsson and Emil Björnson discuss how one can create cell-free networks consisting of distributed massive MIMO arrays. The vision is that each user will be surrounded by small access points that cooperate to provide uniformly high service quality. The conversation covers the key benefits, how the network architecture can be evolved to support the new technology, and what the main research challenges are.

The description also contains some links and the discussion is also interesting to follow. You can jump on to the video directly here.

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Friday 5 November 2021

Deutsche Telekom Launches Indoor Booster 5G Repeater

On his LinkedIn post, Dr. Alex Jinsung Choi, Deutsche Telekom Senior Vice President, Head of Strategy & Technology Innovation and COO of O-RAN Alliance announced the launch of Telekom Deutschland GmbH's Indoor Booster 5G in Bavaria. The post said:

This small low-power repeater brings 5G into offices and homes that did not have sufficient indoor coverage of mobile networks before. It enables customers to experience best streaming, gaming, education services, home office and video conferences with 5G indoors.

I am proud to announce that this new product is result of the cooperation of Deutsche Telekom with our strategic partner SK Telecom. SKT developed and launched 5G repeaters in 2019. In 2020, DT and SKT colleagues trialed a customized 5G repeater in a customer test in Germany which was starting point for the successful launch this year.

Furthermore, the Indoor Booster 5G is the first product of Techmaker GmbH, the tech joint venture of SK Telecom and Deutsche Telekom. I would like to thank all the many colleagues in Techmaker, SK Telecom and Deutsche Telekom who made the project a success!

We looked at SK Telecom's In-building 5G NR Repeaters couple of years back here.

The website explains the working of the booster as can be seen in the picture on the top. All information is in German and is translated using Google translate below: 

The 5G signal is picked up by an antenna on the outside and routed inwards by cable to a so-called booster. This only requires a 230V connection. This results in faster cell phone reception even in remote rooms with stable walls. You can continue to use the Indoor Booster 5G with your existing mobile phone contract.

The Indoor Booster 5G consists of an outside antenna and a booster inside. You should be authorized to have an antenna installed on your building and to grant access.

Couple of FAQ's have interesting info as well:

Why can you only rent the Indoor Booster 5G and not buy it?

Since the indoor booster reproduces the cellular signal, Telekom is the operator of the device and cannot transfer ownership of it to the customer.

Why do I have to commission the installation service?

Since the Indoor Booster reproduces the cellular signal, Telekom is responsible for the operation of the device and must ensure that the radio signal does not interfere with the cellular network. At the installation appointment, you will also be advised where the external antenna is best placed in order to achieve the best possible improvement in performance.

If you own one of these, we would love to hear from you about your experience.

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