Patent ID: 8645678
Filing Date: 2014-02-04
Classification: H04L

Abstract:
1. A method of encrypting data at a physical layer of an orthogonal frequency division multiplex (OFDM) data transmission system, comprising: mapping a binary data sequence to N QAM symbols, wherein N is an integer; modulating a distinct sub-carrier of the OFDM using each of the N QAM symbols in an inverse fast Fourier transform (IFFT) process; buffering L OFDM blocks of the output of the OFDM modulation in a buffer, wherein L is an integer; providing a key stream sequence K with a length of L×N entries; creating encrypted L OFDM symbol blocks {tilde over (x)}(l) by altering the location of each entry of the buffer according to a corresponding element of a key stream sequence K to establish encrypted samples {tilde over (x)} unbuffering and converting the encrypted samples {tilde over (x)} adding a time-domain guard-band sample by copying and prepending a last N