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Spacing Out…Getting the Most out of MIMO with Proper Antenna Spacing

While “MIMO” has been a buzz word in the mobile communications industry for some time, it is only now gaining real traction and will be a key enabler as networks migrate from 4G to 5G.  Base Station Antennas are a critical component in MIMO architectures, and there is a science to proper spacing in order to achieve the highest Quality of Service (QoS) and Quality of Experience (QoE) while minimizing interference and PIM. 

Let’s take a quick look at what how MIMO works, what it brings to mobile networks, and how proper antenna spacing is a key to maximizing throughput.4x4 MIMO image

A Quick Tour of MIMO

MIMO, or Multiple Input Multiple Output, utilizes multiple antennas at both the transmitter and the receiver (smartphone) to increase link reliability and spectral efficiency. Spatial Multiplexing makes it possible to transmit separate data streams from multiple antennas on the same frequencies. Signal processing hardware splits the data into multiple streams and transmits these streams using multiple antennas. The receiver then reverses this process, recreating the original data stream inside the phone. Obviously, propagation conditions between the transmitter and the receiver must be good for MIMO to work effectively.

What’s the result of all this?  MIMO increases the capacity of a cell without using more bandwidth. With 2×2 MIMO (two transmit and two receive) it is theoretically possible to double the throughput, while 4×4 MIMO can quadruple throughput. In an LTE network, the peak throughput using SISO (single input, single output) is about 100 Mbps. Utilizing 2×2 MIMO and 4×4 MIMO, throughput can ideally reach 173 Mbps and 326 Mbps, respectively. 

Mobile operators have implemented 2×2 MIMO in their LTE 4G networks for a number of years and are now beginning to deploy 4×4 MIMO to meet increased data demands.  Just last fall, Samsung’s Galaxy S7 became the world’s first 4×4 MIMO capable smartphone. The challenge with placing four antennas so close together in a phone (along with Wi-Fi, GPS and Bluetooth antennas) is that it can cause the transmission paths to couple, limiting MIMO performance and increasing signal interference.

While handset manufacturers were busy developing smartphones with 4×4 MIMO capable antennas, antenna manufacturers, like Kathrein, were developing 4×4 MIMO ready antennas for the cell sites.  

Optimum Macro Antenna Spacing for 4×4 MIMO

A lot of research that has been done on the proper placement of 4×4 ready MIMO antennas on cell towers. When determining optimum spacing between horizontal antenna columns for 4×4 MIMO, a balance must be found between improving gain while reducing inter-sector interference (I-SI).

Mounting antennas with proper spacing helps operators achieve maximum MIMO performance by keeping the antenna pattern in the “desired” area of the sector, with minimum energy in the “undesired” area where there is higher inter-sector interference.

Sector Power Ratio Image

Measurement studies performed by Kathrein engineers at the low band shows the optimal spacing between columns to be 0.8λ (wavelengths). For perspective, at 780 MHz, one wavelength is about 15 inches. It was determined that at mid band (1.7-2.7 GHz) gain became more important than I-SI to improve 4×4 MIMO performance. Therefore, the preferred spacing between columns for the low band has been set near 0.8λ to ensure I-SI is minimized; however, the spacing at high-band in a shared aperture is chosen for improved gain, near the 1.3λ or 1.8λ spacing, (based on bands under the radome) in an attempt to minimize I-SI as well.

Kathrein Makes Antenna Spacing Easy

Antenna Bracket for side by side

2 X Panel Mounting Kit

Kathrein recently released new 4, 8 and 12 port macro antennas that are 508 mm in width.  These wider antennas support 4×4 MIMO under one radome (click to view the datasheets: 80010901, 80010964, 80010991).  Operators can mount these antennas and be 4×4 MIMO ready without worrying about spacing two separate antennas.  For 378 mm antennas, Kathrein offers 2x Panel Mounting Kits (85010103/850108) that provide pre-configured optimum spacing for 4×4 MIMO applications.

Moving Forward with MIMO

MIMO is already offering huge dividends by increasing network throughput and capacity.  Moving forward, we will see more 4×4 MIMO implementations, as well as 8×8 MIMO, and eventually 64×64 Massive MIMO as operators move into 5G and beyond.

Learn More by visiting us at MWC Americas in San Francisco, CA, September 12-14: Booth S.1042.

Kathrein and CommScope Sign Extensive Cross-License Agreement

Kathrein’s Juergen Walter and Commscope’s Ben Cardwell

Press Release:

Rosenheim/Hickory, 5 April 2017 – Kathrein and CommScope, industry leaders in network infrastructure solutions, have entered into a long-term global agreement to cross-license portions of their patent portfolios, increasing each company’s ability to develop new solutions, serve customers and compete in the global market. Under the agreement, both companies can access and implement the other company’s patents and technologies globally. The cross-licence agreement relates to passive base station antennas, distributed antenna systems (DAS) and filters.

“This is a win-win for both parties, demonstrating our mutual commitment to innovation and wireless industry development,” said Ben Cardwell, Senior Vice President, CommScope Mobility Solutions. “CommScope engineers will enjoy greater freedom of design, accelerating our research and development in antennas and filters, while Kathrein gains access to our valuable digital DAS patents.”

Kathrein is the first and only company that CommScope has licensed to its digital DAS patent portfolio. As part of the agreement, Kathrein agreed to an undisclosed upfront payment and ongoing royalties specific to the digital DAS portfolio. CommScope gains access to Kathrein’s robust passive base station antenna and filter portfolios. Further details of the agreement are not being disclosed.

“We are pleased with the global cross-licence agreement with CommScope,” said Jürgen Walter, Executive Vice President, Solutions Division, Kathrein. “This agreement reflects the two leading companies’ joint view that innovation sharing and standardisation of technology is critical to driving and accelerating industry evolution as we head into 5G customer requirements and future deployments.”

CommScope and Kathrein have invested substantial resources in bringing their wireless solutions to market and have built substantial patent portfolios to protect their respective investments. Both companies are committed to protecting their intellectual property rights. 

About Kathrein

Kathrein is a leading international specialist for reliable high-quality communication technologies. The company is an innovation and technology leader in today’s connected world. Its ability to provide solutions and services enable people all over the world to communicate, access information and use media, whether at home, at the office or on the road. The business covers a broad spectrum: from mobile communication and RFID solutions, to satellite reception, broadband and broadcast technology, to transmission and reception systems in vehicles. As a hidden champion and family-owned enterprise, Kathrein has been working on the technologies of tomorrow since 1919. The company takes pride in its dedicated employees and passion for customers and quality. Find out more about Kathrein at www.kathrein.com.


About CommScope

CommScope (NASDAQ: COMM) helps companies around the world design, build and manage their wired and wireless networks. Our vast portfolio of network infrastructure includes some of the world’s most robust and innovative wireless and fiber optic solutions. Our talented and experienced global team is driven to help customers increase bandwidth; maximize existing capacity; improve network performance and availability; increase energy efficiency; and simplify technology migration. You will find our solutions in the largest buildings, venues and outdoor spaces; in data centers and buildings of all shapes, sizes and complexity; at wireless cell sites; in telecom central offices and cable headends; in FTTx deployments; and in airports, trains, and tunnels. Vital networks around the world run on CommScope solutions.

Kathrein Europe Press Contact

Anton Maier

Email: presse@kathrein.de

Phone: +49 8031 184 299

Kathrein U.S. Media Contact

Capriccio Martin

Email: pr@kathrein.com

Phone: +1 214-238-8822