Dish Network has stepped up its offense against a Sprint proposal that it says could "severely jeopardize" its wireless plans.

The two companies are fighting over the FCC's proposed rule changes to Dish Network's AWS-4 spectrum, 40 MHz of satellite spectrum it wants to use for a land-based LTE network.

Dish cannot move forward with its LTE service until the FCC changes its regulations on the AWS-4 spectrum, and it is trying to block a Sprint proposal that would shift the band up 5 MHz from 2000-2020 MHz to 2005-2025 MHz.

Sprint wants the FCC to shift the band plan so that adjacent PCS spectrum in the 1915-1920 MHz and 1995-2005 MHz blocks can be put up for auction, a sale that could benefit Sprint's LTE service.

Sprint has said it "values the H-block as LTE expansion spectrum" and will bid on it if the FCC puts it on the auction block. Sprint currently uses a separate portion of the PCS band for LTE, making the H-block particularly advantageous.

But Dish says the shift could have a major impact on its ability to launch LTE in a timely manner. In a Monday FCC filing, Dish accused Sprint of downplaying the impact of the band shift.

Moving the band up 5 MHz would force the 3GPP to restart its standards process for the AWS-4 band, Dish argued, and create "significant new" interference issues with nearby government and broadcast transmissions.

“Restarting this process would significantly delay the expected completion of LTE Advanced specifications for the band and severely jeopardize Dish’s commercial plans," Dish said.

Dish also said Sprint had exaggerated the readiness of the H-block for LTE and was pushing for unnecessarily stringent emission limits on its AWS-4 holdings.

“Not only is it unclear whether the H-block can ever be used for full-power broadband LTE, but making the changes Sprint proposes would sacrifice a substantial amount of AWS-4 spectrum," Dish said.

Sprint has yet to file a rebuttal to Dish Network's remarks but told the FCC earlier this month that the H-block must be protected for future bidders.

“While Sprint continues to support awarding Dish Network the ability to deploy terrestrial broadband services in its Mobile Satellite Services (MSS) spectrum, realization of this goal must not come at the cost of idling the valuable H-block spectrum,” Sprint said, pushing for emission limits on Dish transmissions. “Impairing the H-block would frustrate the principal benefits potential H-block bidders hope to achieve in acquiring the spectrum.”

The FCC has given no indication when it will finalize its AWS-4 rules. FCC Chairman Julius Genachowski and Dish Network Chairman Charlie Ergen will speak at PCIA’s conference next week, sparking rumors of a possible announcement.