The introduction of millimeter-wave (mmWave) spectrum for 5G networks presents network operators with a unique, and in many cases, first of its kind assortment of challenges and opportunities.

The vast majority of 5G deployments to date ride on mid- or low-band spectrum, but the dramatic gains that mmWave spectrum can deliver in speed, capacity, and lower latency are without compare in the context of mobile architecture.

However, the costs operators will have to endure to deploy robust and reliable 5G mmWave networks are massive. And therein lies the rub. At least until equipment, and specialized use cases can help offset those costs.

Much of the early hype around 5G focused on mmWave because executives could point to gigabit-plus speeds, lower latency, and fantastical use cases, but the economics don’t bear out and are unlikely to until later this decade.

The level of interest and investment in mmWave 5G depends very much on the spectrum availability and demands of each market. Some analysts suggest mmWave is on the upswing and others view it as the final piece of the 5G puzzle that probably won’t manifest itself at global scale until the latter half of this decade.

“Global deployment of 5G networks based on millimeter-wave spectrum has been limited compared with that using sub-6Ghz, but momentum is building,” Kester Mann, director of consumer and connectivity at CCS Insight, wrote in a research note. Commercial mmWave 5G networks are available in the U.S., Japan, Italy, and Singapore, and supporting spectrum has been allocated in at least 10 other countries with others underway this year, he added.

Industry trade group GSMA is doing its part to fuel that momentum. A recent report from GSMA Intelligence concluded that mmWave presents network operators with cost savings in some instances when it’s deployed in addition to or instead of mid-band spectrum.

It can, for example, deliver download speeds in excess of 100 Mb/s at a lower cost than a network running exclusively on 3.5 GHz spectrum in dense urban areas, according to GSMA. The analysts also pointed to potential cost savings for operators in using mmWave for fixed wireless access (FWA) and indoor coverage for enterprises and consumers.

Mann’s evaluation of those conclusions noted those potentially lower costs and GSMA’s estimate that an acceleration of 5G mmWave deployments in the second half of this decade will generate an annual boost to the global economy are predicated on the arrival of higher-performance and lower-cost mmWave equipment.

“Like so much in telecommunications, scale will be critical to the success of millimeter wave and its long-term adoption. This means the creation of a supporting ecosystem, built on widespread availability of millimeter-wave spectrum, and including an abundant supply of network infrastructure and enabled devices at low prices,” Mann wrote.

Analysts at Signals Research Group, also in a recent report, pointed to recent technological gains that extend the scope and viability of mmWave for network operators. “In addition to increases in user data speeds, there are new 5G New Radio (NR) mmWave use cases, thanks to technology advancements” and market maturity, the analysts wrote.

The recent introduction of high-power consumer premise equipment (CPE) and modifications to the configuration of the mmWave radio channel make the prospect of mmWave for FWA more compelling, according to Signals Research Group. Some of this next-generation equipment can effectively extend the range of mmWave signals to several kilometers versus a few blocks, and indoor deployments of mmWave sites “provide surprisingly good coverage for enterprise use cases,” it added.

Meanwhile, industry chatter about mmWave in the U.S. “has quieted down really significantly over the past few months,” Dan Hays, partner at Strategy&, PwC’s consultancy, told SDxCentral in a recent interview. 

“It was a very hot topic going into 2020, but I think that some of the luster seems to have worn off. And while it’s still an important tool in the 5G toolkit, I think there’s a growing realization that deploying 5G on millimeter wave really isn’t going to be feasible at scale beyond very dense urban cores,” he said. 

Verizon stands out as an exception in the U.S. and globally on mmWave, partially because of its spectrum position, having framed much of its 5G strategy around its Ultra Wideband network that reached 64 U.S. cities at the end of 2020. CEO Hans Vestberg last month said the operator intends to double the amount of 5G Ultra Wideband sites by adding 14,000 new mmWave sites to its network in 2021, enabling it to reach an additional 20 cities in the process.

T-Mobile US, the first domestic operator with a nationwide 5G network running on unencumbered low-band spectrum, contends that mmWave is important to the 5G story, but only so far as it provides a capacity layer where needed. Neville Ray, the operator’s president of technology, argues that the notion mmWave can deliver multi-gigabit speeds at scale is mythical. 

T-Mobile deployed mmWave 5G networks in parts of 6 U.S. cities, but has shifted its strategy to low- and mid-band 5G deployments since mid 2019.

AT&T’s 5G+ network is currently available in parts of 38 U.S. cities, but it too appears to be focusing mostly on lower spectrum band deployments for the foreseeable future.