Where the bands are widely separated in frequency, parallel transmit and receive signal path circuits must be provided, which increases the cost, complexity and power demand of multi-band devices.
The Advanced Wireless Services (AWS) 1700 MHz band is also seeing increased usage.
[citation needed] In the United States only, the two largest carriers are instead implementing 4G LTE in the 700 MHz band, which was reallocated from TV broadcasting during the DTV transition.
TV stations were forced to move to lower UHF and even far worse VHF frequencies with poorer mobile TV and even regular terrestrial TV performance[citation needed], because the 700 MHz band has better radio propagation characteristics that allow mobile phone signal to penetrate deeper into buildings with less attenuation than the 1700 MHz or 2100 MHz bands.
Verizon Wireless formerly held frequencies just above TV channel 51, which is still in use, causing adjacent-channel interference that is preventing the carrier from using them until the planned top-down spectrum repacking occurs.