5G base station architecture, Part 1: Evolution

-May 16, 2015


I interviewed Roger Nichols, Keysight 5G Program manager to get his perspective of test challenges that 5G designers will need and how Keysight will support them.

Nichols is the 5G Program Manager for Keysight Technologies.  His 30 years of engineering and management experience in wireless test and measurement at Hewlett-Packard, Agilent Technologies, and Keysight spans roles in manufacturing, R&D, and marketing,  and crosses the evolution from analog cellular radio through LTE and beyond.  He spent seven years as the Marketing Director for Keysight’s (Agilent’s) Mobile Broadband Operation responsible for the wireless test-sets and systems that are used in all major design and certification labs as well as manufacturing facilities worldwide. Nichols holds a BSEE from the University of Colorado, Boulder.


Nichols told me that he will be giving an IMS Keynote address on 5G this May 19 in Phoenix entitled “5G Wireless: A Measurement and Metrology Perspective” in the MicroApps Pavilion.

Nichols said that for the first time Next-generation wireless is being much more viewed from a user perspective and more user technologies will come from that.

5G will involve significant changes to radio systems under 6GHz but will also add access technologies above 6 GHz both of which will drive significant infrastructure challenges.  Fiber-optic and other backhaul need to be faster with lower latency as well.

From a Test & Measurement point of view a broad range of technologies will be covered. Most of Keysight’s product lines and software will have opportunities across the board in photonics, millimeter wave, and MIMO test; plus digital busses will need to be significantly faster.

Challenges for 5G will be:

  1. Millimeter wave: This used to be primarily in the aerospace and military/defense arenas. Now this technology will go commercial in 5G so Keysight solutions will be there for these customers to test their system designs.
  2. MIMO: As we approach higher order MIMO traditional approaches could increase costs in Test & Measurement equipment for commercial customers. Keysight is working on ways to streamline testing of these “massive MIMO” techniques for the commercial wireless industry.
  3. Radio measurements: Test equipment connection to the Device Under Test (DUT) can be done with cables of transmission lines, but in millimeter wave, antennas are likely to be connected directly to the IC and measurements will be challenging. Even under 6 GHz the antenna connections could be eliminated a base station. How can we make calibrated measurements? Today’s methods are complex and expensive and Keysight is working on the challenge to simplify but retain confidence in the metrology.

Keysight works very closely with developers in the commercial and academic research space to evolve their Test & Measurement capabilities.

I asked Nichols if Keysight could somehow modify their existing solutions to bridge the gap to 5G test technology as designs develop. Nichols stated that almost all 5G work to date is research and  tools like MATLAB are widely used by their customers (Keysight uses these as well). Given this, simulations will be the first line of verification of new design architectures and that will have to develop along with 5G progress first. But Keysight has gone a step further with the 5G Baseband Exploration Library in SystemVue. See Figure 11.



Figure 11: The W1906BEL 5G Baseband Exploration Library gives designers ready-to-use reference signal processing IPs for 5G technology research in C++ format (Image courtesy of Keysight)

This Library, W1906BEL, is used to explore baseband technologies for 5G. Couple this with Keysight hardware and this is a start to the road to 5G development that will surely evolve as we proceed forward.

There will be ambitious claims in components that Test & Measurement will have to prove.

One challenging area will be at 60 GHz using Wideband Modulation. Keysight has created a flexible solution for WiGig Testing. Wireless Gigabit (WiGig) is expected to enable wireless connectivity of up to 7 Gb/s in data, display and audio applications. IEEE 802.11ad is the industry standard for this development.

Nichols’ favorite quote is from a China Mobile paper which stated that with current architectures 1.1 Million base stations consumed 67% of the network’s 14 Billion KWH power consumption in 2012. Power consumption is dominated by RF power-amplifiers and the air conditioning that is needed to keep the temperatures reasonable for operating purposes and reliability. By late 2014 they had built an additional 720,000 4G base stations which no doubt puts a further strain on the power budget.

There is continuous work to make RF PAs more energy-efficient with signal processing techniques. Would a more digital-oriented process make for better efficiency? That remains to be seen but research and design groups around the world are hot on this trail.

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