Sprint Nextel Corp plans to upgrade its network in time to launch high-speed wireless services by the middle of 2012 and expects to complete its upgrade by the end of 2013, a top executive for the company said on Friday.

Sprint also said at an investor event in New York that its partnership with LightSquared should help it meet its spectrum needs through 2015.

The company, which started taking pre-orders for the Apple Inc iPhone on Friday, said that while the device is more expensive than others, the iPhone will be quite accretive to profitability and cash flow over time.

Chief Executive Dan Hesse said he expects the popular device to be one of Sprint's most profitable, but he did not give specifics.

Sprint plans to upgrade its network using Long Term Evolution (LTE), the same high-speed wireless technology being used by its two bigger rivals AT&T Inc and Verizon Wireless, a venture of Verizon Communications Inc and Vodafone Group Plc.

(Reporting by Sinead Carew and Supantha Mukherjee; editing by Gerald E. McCormick)

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