Time Warner Cable's TV channel shift draws interference from Verizon LTE smartphones

Reports of spectrum interference causing problems for LTE networks are growing more commonplace, with everything from fluorescent lights to electronic cash registers being implicated.  In the latest twist, Verizon Wireless (NYSE:VZ) LTE data service is getting the blame for interfering with some channels delivered over the Time Warner Cable system in Raleigh, N.C.

A report from TV station WRAL said TV channels that Time Warner Cable recently relocated to the 700 MHz band of its cable system--including WRAL's own channel--are being negatively impacted by Verizon's LTE transmissions. According to the report, "When a 4G device and a cable box are in the same room, they can come into conflict."

"We apologize for the inconvenience and are working on a solution that will resolve this problem definitively in the coming weeks," Time Warner Cable said in a statement to WRAL. The resolution will involve shifting WRAL and Fox 50 off of the 700 MHz band.

Capital Broadcasting execs demonstrate jitter problems experienced when using 700 MHz spectrum near a TWC cable box. (Source: Capital Broadcasting)

In early November, Sam Matheny, vice president of policy & innovation at Capital Broadcasting, which owns WRAL, wrote a column decrying the interference issue. Matheny said he began having problems with his cable TV video "becoming very pixelated and jerky" after he brought home his new Apple (NASDAQ:AAPL) iPhone 5S and left it on his nightstand.

Matheny wrote that the immediate solution "is to use the 700 MHz band on cable systems for services that don't require reliable delivery of linear programming," and emphasized that cable operators should avoid putting their most viewed channels in this space.

Noting that at least some of TWC's cable boxes apparently do not have the necessary shielding to block interference from other devices, Matheny called for boxes with better shielding to be built starting immediately to "accommodate the new reality of the 700 MHz band."

However, wireless consultant and engineer Steven Crowley told Ars Technica that the more likely source of interference is RF energy being conducted into the cable box via power cable or coaxial cable connections.

On Dec. 6, Verizon Wireless reached out to FierceWirelessTech to add its side of the story. "Verizon Wireless operates within the 700 MHz spectrum which is our FCC-approved and licensed frequency band.  We have transmitted on this frequency for years and adhere to FCC rules and regulations for transmitting in the 700 C band," said spokesman Paul Macchia.

For more:
- see this WRAL article and this column
- see this DSL Reports article
- see this Ars Technica article

Related articles:
Industry wrestles with the growing problem of spectrum pollution
AT&T's LTE network impaired by salon's fluorescent light
FCC adopts order banning wireless microphones in 700 MHz band

Article updated Dec. 6, 2013, to include a comment from Verizon Wireless.