Submitted on: 14 October 2009.
Revised on: 27 December 2009.
Accepted on: 13 January 2010.
___________________IEEE Wireless Communications Letters
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Submitted on: 30 January 2008.
Revised on: 06 March 2008.
Accepted on: 01 April 2008.
___________________IEEE Wireless Communications Letters
Submitted on: 08 August 2009.
Revised on: 01 December 2009.
Accepted on: 16 January 2010.
___________________IEEE Wireless Communications Letters
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Submitted on: 02 March 2009.
Revised on: 21 June 2009.
Accepted on: 10 August 2009.
___________________IEEE Wireless Communications Letters