Patent ID: 7672392

Claim:
A method in a digital communication system for transmitting a modulated bit stream comprising modulated user data and modulated dummy data, wherein the modulated user data is represented by symbols from a symbol alphabet M, the modulated dummy data is represented by a symbol m 0 , comprising: (a)—generating ( 601 a ) symbols q 0 , . . ,q j randomly from a predefined symbol alphabet Q being a subset of the symbol alphabet M, (b)—scrambling ( 602 a ) the modulated bit stream by performing bitwise modulo-2 addition between the modulated bit stream and the randomly generated symbols q 0 , . . ,q j from Q, and (c)—transmitting ( 603 a ) said scrambled modulated bit stream, wherein the predefined symbol alphabet Q is defined so that the transmit power level of the dummy data is substantially lower than the transmit power level of the user data.