Clearwire branched out in its WiMax mobile data service on Monday, launching a prepaid brand called Rover. Rover uses the same network as Clearwire's existing Clear service but offers simpler pricing plans and unique client devices.

Consumers can pay $50 for a month of data service, $20 for a week or $5 for a day, with no contracts or data caps. Rover starts out by offering two devices: the Rover Puck portable WiFi router, priced at $149.99, and the Rover Stick USB modem, for $99.99.

Subscribers can buy Clear service without a long-term contract already, but about 80 percent of Clear users are on contracts, Clearwire Chief Commercial Officer Michael Sievert said on a webcast held to announce Rover. With the new brand, Clearwire is taking aim at consumers who want simpler pricing, especially young adults aged 18-24 who are buying their own Internet access for the first time, he said.

The prepaid model Rover is using, also known as "pay as you go," differs from prepaid voice plans in that customers buy a period of coverage rather than a quantity of use, such as minutes or megabytes. Sprint Nextel subsidiary Virgin Mobile offers an unlimited "pay as you go" 3G data plan for $40 per month.

Rover will work only on Clearwire's WiMax 4G network and not on Sprint's 3G network, as some other Clearwire plans do. That means coverage is limited to the 49 markets where the 4G network is already built out. In addition, users can't sign up for Rover plans using Clear-branded client devices, Sievert said.

The new service is available now online and through Best Buy, Clear stores and independent wireless dealers in Houston and St. Louis. Retail availability will expand to other markets later. After buying a device and service, customers will be able to pay for more service online, with gift cards, in cash at a retail store or automatically through a credit or debit card. Though young adults are the target market for Rover, the service is available to all classes of customers, including businesses, Clearwire executives said. Rover is not available through Clearwire's wholesale partners, such as Sprint Nextel and Comcast.

As with Clear, there is no cap on the amount of data users can download on Rover. The service and client devices can be used with popular VoIP (voice over Internet Protocol) services, Clearwire said. Clearwire is offering a 14-day "no-hassle" return policy for Rover devices, and new customers will receive two free days of service.

Analyst believe the market for prepaid mobile data is poised for growth. Apart from the data plans consumers buy for smartphones, mobile data services mostly have been associated with business users, said IDC analyst Carrie McGillivray. Prepaid plans such as Rover's make this type of service more accessible. "It's giving consumers a chance to experiment with mobile broadband," McGillivray said.

Prepaid voice service boomed last year as consumers grew more cautious about their budgets, and this year may be a big year for prepaid data, McGillivray said. IDC estimates about 20 percent of mobile data customers will be prepaid this year. Though McGillivray only expects that proportion to grow to 22 or 23 percent by 2014, she believes there's strong growth potential in the market Clearwire is targeting.

Enterprises, and employees who buy their data plans for business use, are likely to stick with postpaid plans because they are more predictable and easier to account for, said Yankee Group analyst Chris Nicoll.

The Rover Puck may be ideal for consumers who own an array of WiFi devices. It can connect as many as eight devices to the Internet via the Clearwire network, which the carrier said offers downstream speeds between 3Mbps (bits per second) and 6Mbps. The Puck's battery will last about four hours on a charge, according to Clearwire. The Rover Stick USB device, which works on a single device, is compatible with both PCs and Macs and connects directly to the WiMax network.

Users need to live in a WiMax coverage area to order a Rover Puck or Rover Stick online and have it sent to them. Clearwire already offers service in cities including Chicago, Las Vegas and Dallas-Fort Worth, but not yet in New York City, the San Francisco Bay Area and Los Angeles.

With Verizon Wireless planning 4G LTE (Long-Term Evolution) service by year's end and T-Mobile USA deploying HSPA (high-speed packet access) Plus, which can carry as much as 21Mbps, Clearwire should have immediately launched Rover at retail stores in all its markets, Yankee's Nicoll said.

"Clearwire's not going to be the only game in town, and they're going to be playing catch-up in the Tier One cities," Nicoll said. "One of the ways they can get ahead of the curve is to make a big splash with these types of devices... And I just don't think they are."