The demand for millimeter wave products is quickly moving into the consumer market place. Historically, both Wi-Fi and cellular services have been operating in the crowded frequency bands under 6 GHz. Over the next few years, we expect to see new wireless communications standards widely adopted into new products (including smartphones, head-mounted displays, hot spots, etc.) that operate at mmWave frequencies over 24 GHz. 1 For example, the IEEE 802.11 working group has released two new standards, 802.11aj and 802.11ad, operating in the 40 GHz and 60 GHz unlicensed mmWave bands respectively, and is pursuing a new 802.11ay standard in the 70 GHz band. In addition, the 3GPP standards organization has recently introduced a 5G new radio (NR) 2 cellular standard capable of initially operating in the 28 GHz and 39 GHz mmWave bands as well as sub-6 GHz bands.
The GSM Association 3 has set forth five mobile industry goals for the 5G era, two of which are: “to provide boundless connectivity for all” and “to deliver future networks innovatively and with optimal economics.” Likewise, the IEEE 802 organization has set forth five criteria (5C) as conditions for communications standards development work (CSD) 4, three of which are: “broad market potential” “technical feasibility,” and “economic feasibility”. These requirements are appropriate as any new wireless standard needs to fulfill pressing customer needs while also being technically and economically viable to them.
There are, however, several new testing challenges that must be overcome in order to make mmWave products economically viable. For example, unlike sub-6 GHz products that can be tested with contacted probes, mmWave requires over-the-air testing techniques. In addition, mmWave 802.11 and 3GPP NR wireless standards specify much wider component carrier (CC) bandwidths in the range of 400 MHz to 4 GHz, as opposed to only 160 MHz for sub 6 GHz. Moreover, engineers and technicians who are experts in mmWave technology are very scarce in the market place.
In order to fulfill the technical and economic feasibility criteria of mmWave 802.11 and 3GPP NR standards, test equipment vendors must respond quickly in order to meet these new mmWave test requirements: 1) > 24 GHz frequency test coverage; 2) > 400 MHz CC bandwidth support; 3) OTA (over-the-air) test fixtures; and 4) faster, simpler, and smarter test equipment. The first three test equipment requirements relate to both the technical and economic feasibility criteria, whereas the fourth requirement pertains primarily to the economic feasibility criterion as we discuss next.
1 The radio frequency (RF) spectrum above 24 GHz is usually referred to as the mmWave spectrum due to the very short wavelengths as compared to RF spectrum in the sub-6 GHz range.
2 See http://www.3gpp.org/news-events/3gpp-news/1929-nsa_nr_5g
3 E. Obiodu and M. Giles, “The 5G era: Age of boundless connectivity and intelligent automation,” GSMA, Feb. 27, 2017. [Online]. Available: https://www.gsmaintelligence.com/research/2017/02/the-5g-era-age-of-boundless-connectivity-and-intelligent-automation/614/
4 See https://mentor.ieee.org/802.11/dcn/14/11-14-1152-08-ng60-ng60-proposed-csd.docx
Faster, simpler, and smarter mmWave test equipment is needed for high-volume manufacturing so that the product will be economically feasible. Faster test equipment minimizes the required set-up time, calibration time, and unit test time throughput, all of which have a direct impact on the cost of test (COT), which in turn affect the product unit cost. Simpler test equipment makes it easy to use and is “plug-and-play” for the vast majority of users in the manufacturing environment who are not mmWave experts, and also accelerates the time-to-market of mmWave consumer products. Smarter test equipment simplifies dealing with the new mmWave test challenges for a larger group of R&D developers. Smarter test equipment also has embedded software that optimizes the units per hour (UPH) throughput time, speeds up the troubleshooting time of failed units, and makes the test equipment accessible to a wider group of R&D and software developers.
Whereas most bench rack-and-stack mmWave test equipment available in today’s ecosystem fulfills the frequency, bandwidth and OTA test requirements of the new 802.11aj/ad/ay and 5G 3GPP NR standards in the R&D lab, there is still work to be done in the test industry as mmWave products enter the high-volume manufacturing line. Fortunately, leading test equipment companies are starting to introduce mmWave test equipment that is faster, simpler, and smarter for the manufacturing environment, thereby paving the way to fulfilling the economic feasibility criterion of the both the GSM Association and IEEE 802 CSD 5Cs.
Dr. Jeorge S. Hurtarte is currently RF Market Segment Manager at LitePoint Corporation in Sunnyvale, CA, USA. Prior to joining LitePoint, Dr. Hurtarte held various technical and management positions at Teradyne, TranSwitch, and Rockwell Semiconductors. He holds Ph.D. and B.S. degrees in electrical engineering, an M.S. in telecommunications, and an M.B.A. Dr. Hurtarte has served on the Advisory Board of Directors of the Global Semiconductor Alliance, TUV Rheinland of North America, and the NSF’s Wireless Internet Center for Advanced RF Technology. He is the secretary of the IEEE 802.11ay task group. He is also the lead co-author of the book Understanding Fabless IC Technology. (e-mail: jeorge.hurtarte@litepoint.com)