In a few years, some U.S. broadband markets could be much more competitive than they are today.

A slew of tech and telecom giants are keen on using high-frequency spectrum bands to drive the rollout of fixed wireless broadband services, via 5G and other radio technologies. The group includes Facebook (FB) - Get Report , which just announced it's working with Qualcomm (QCOM) - Get Report  to commercialize its Terragraph fixed-wireless system for urban areas. It also includes Verizon (VZ) - Get Report , T-Mobile US (TMUS) - Get Report and Alphabet's (GOOGL) - Get Report Google Fiber unit.

Fixed wireless still faces major questions related to technical issues such as range, in-building signal strength and potential congestion in high-density urban zones. And even if these issues are addressed, major network rollouts will still likely take a few years and often require using the fiber infrastructures of existing ISPs.

But advances in silicon and radio technologies make fixed wireless far more intriguing as a broadband alternative than it was a decade ago. Factor in the size and resources of its backers, and there are good reasons for investors in cable ISPs such as Comcast (CMCSA) - Get Report and Charter (CHTR) - Get Report  to closely monitor its rise. Even if there's no need to panic at this point.

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