Comcast announced today it has invested an undisclosed sum in seed-round funding to mobile WiMax company Cartiza.

Founded in late 2006, the Boston, Mass. company has previously raised $12.6 million in funding, according to the Boston Business Journal. Cartiza is reportedly in stealth mode, working on infrastructure software for the next generation of mobile broadband. While the company website doesn’t say so, it is working with WiMax: Cartiza is listed in the WiMax Forum membership roster.

In April, Comcast was part of a group of industry giants, including Google, Time Warner, Intel, and Bright House Networks, that invested $3.2 billion in WiMax company Clearwire. Other WiMax start-ups are also getting money in anticipation of spending on WiMax infrastructure. One such start-up is BridgeWave Communications, which last week announced it had raised $10.3 million to create wireless transport infrastructure for WiMax and LTE (long-term evolution) cell phone networks.

Louis Toth, Managing Director at Comcast Interactive Capital, already had ties with Cartiza. According to his CIC profile page, he is “involved as a Director, Board Observer or adviser” for Cartiza and six other companies. However, it’s unclear if he took this role before funding Cartiza.