Samsung has started research and development on Distributed FD-MIMO, which has the potential to become the next generation of radio technology. With Distributed FD-MIMO, Samsung aims to continue the innovation stream and achieve better performance and come up with another success story similar to FD-MIMO to take the industry forward to the next level.
FD-MIMO (also known as Massive MIMO, hyper MIMO, very large MIMO) is the use of a large number of antennas, tens, hundreds, and thousands, to dramatically increase the throughput and energy efficiency to a multitude of communications devices. It is commonly seen as the solution to many of the challenges associated with upcoming 5G technologies, especially in extremely high traffic urban areas that also require many very high throughput connections.
Samsung has been actively leading the FD-MIMO (also known as Massive-MIMO) standardization process in 3GPP, 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 noticed a performance enhancement idea when they examined the pain point of the current FD-MIMO technology for the premium sub-1 GHz band. In this band, the wavelength of the RF signal becomes too large for a large-scale antenna array system like FD-MIMO to be feasible. An FD-MIMO RF Unit (RFU) at 700 MHz would roughly be the size of a Mini Cooper car. It is impractical to deploy such bulky antenna system at the top of a tower, due to excessive weight and size.
To bring the benefit of FD-MIMO to low frequency bands, one promising idea that came to their attention is the Distributed FD-MIMO (D-FD-MIMO) technology. In an implementation example shown in the figure, Samsung broke down a large 32-antenna FD-MIMO system into four modules (similar to the Lego toy pieces, and hence the nickname Lego MIMO!). The Lego MIMO modules have much smaller size, and they can be deployed far apart.
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.
Samsung have developed a hardware prototype and performed field tests 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.
Charlie Zhang, SVP and Head of SMI Lab, Samsung Research America at Samsung Electronics, stated that Massive MIMO is a prime example of how the industry stakeholders get together, take an initial theoretical concept and transform it to a mainstream 5G technology in less than a decade.
A significant amount of work needs to be done before they can accurately quantify the benefits of the D-FD-MIMO technology, but these initial results are certainly promising and show great potential for this new breakthrough of the MIMO technology.
There is huge potential in Massive MIMO technology and Samsung has been at the forefront of its development. They plan to remain committed to advancing the technology over the years to come.
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