Sprint and Clearwire are splitting on plans to develop a high speed network based on WiMax technology, according to a report this morning. According to sources cited by the Wall Street Journal, the two firms parted ways due to the departure of Sprint's CEO, Gary Forsee, last month. Kirkland, Wash.-based Clearwire--which is backed by more than $1 billion in investments--has been focused on creating a nationwide wireless Internet network using the WiMax technology standard. Clearwire is headed by telecom mogul Craig McCaw, and backed by Intel and Motorola.