SHANNON'S LAW

A statement defining the theoretical maximum rate at which error -free digits can be transmitted over a bandwidth -limited channel in the presence of noise , usually expressed in the form C = W log 2 (1 + S / N ), where C is the channel capacity in bits per second , W is the bandwidth in hertz , and S / N is the signal-to-noise ratio . ( 188 ) Note: Error-correction codes can improve the communications performance relative to uncoded transmission , but no practical error correction coding system exists that can closely approach the theoretical performance limit given by Shannon 's law.