Clearwire will begin offering pay-as-you-go services, according to documents filed with the SEC ahead of its previously-announced webcast today.

The WiMAX operator said last week it would unveil plans to serve a new customer segment in a webcast held today but had not given further details.

Clearwire’s entry into the pay-as-you-go space, which is typically equated with prepaid services, will face significant competition from carriers like Virgin Mobile, which recently dropped the price of its unlimited, prepaid, 30-day mobile broadband plan to $40.

Virgin Mobile’s mobile broadband service runs on Sprint’s 3G network while Clearwire can leverage its 4G network to differentiate its mobile broadband services.

Dan Hays, head of the telecom practice at the PRTM consulting firm, says Clearwire’s foray into the pay-as-you-go space stands to “significantly expand Clearwire’s market and attract new customers,” according to a research note.

Hays also expects Clearwire to partner with rural WiMAX operators to expand coverage as Verizon and AT&T prepare to deploy their competing LTE networks.

Clearwire’s announcement begins at 10:30 a.m. Central. Wireless Week will have additional details after the announcement.