Patent ID: 7804917
Filing Date: 2010-09-28
Classification: H04B,H04L,H04W

Abstract:
1. A clear channel assessment system, comprising: a double-energy window module capable of receiving a digital signal at a first frequency, the digital signal having a plurality of symbols, and detecting a difference in energy that occurs at the start of each symbol and using the difference to determine if a channel is clear; the module comprising: a first shift register capable of receiving the digital signal; a second shift register, coupled to the first shift register, capable of receiving output of the first shift register; a first energy calculator, coupled to the first shift register, capable of calculating an energy of the first register; a second energy calculator, coupled to the second shift register, capable of calculating an energy of the second shift register; an adder, coupled to the first energy calculator and the second energy calculator, capable of determining a difference in energy of the first and second registers; a latch, coupled to the adder, capable of latching the difference in energy; and an energy difference processor, coupled to the latch, capable of determining if a channel is busy based on the latched energy difference by