Unlicensed: It's What's Next for US Mobile Operators

Three out of the big four US mobile operators are now gearing up to bolster 4G speed and capacity on their networks using unlicensed spectrum for LTE, as more compatible devices are becoming available.

Verizon Communications Inc. (NYSE: VZ) is the latest, as spotted by wireless engineer Steve Crowley, with the operator looking to test 5GHz LTE-Unlicensed (LTE-U) in California, North Carolina, Oklahoma and Texas.

Earlier in April, Light Reading revealed that both AT&T Inc. (NYSE: T) and T-Mobile US Inc. are planning to test network equipment at 3.5GHZ during this year. (See US Interest Grows in 3.5GHz Wireless Broadband .)

Unlicensed LTE will be incorporated with existing licensed 4G infrastructure -- typically as tiny small cell basestations -- to bolster performance as part of ongoing LTE-Advanced upgrades. The unlicensed radio channels will be combined with licensed spectrum through Carrier Aggregation (CA), a method of bonding separate radio channels for more speed and capacity.

This means that devices will also need to support unlicensed LTE at 3.5GHz and 5GHz. Milan Milanovic at Cellular Insights noted that the Samsung Corp. Galaxy S8 is already primed to support 5GHz LTE-U in a tweet.

Qualcomm Inc. (Nasdaq: QCOM), meanwhile, told Light Reading recently that specific support for the unlicensed 3.5GHz CBRS band will arrive in smartphones in the US next year.

3.5GHz also has interest in Asia and Europe for future 5G usage, although typically as a licensed band. (See Eurobites: Elisa, Nokia Test 5G on 3.5GHz Band.)

— Dan Jones, Mobile Editor, Light Reading