Improved algorithms based on polynomial cancellation coding to deepen spectrum notch

In orthogonal frequency division multiplexing (OFDM) systems, spectrum notch can be generated to mitigate interference towards other narrow-band services by directly turning off corresponding subcarriers. However, the inter-carrier interference may limit considerably the produced notch depth. In this letter, two improved algorithms to deepen spectrum notch in OFDM system are proposed. Different from the Polynomial cancellation coding (PCC) method, the data symbols transmitted on a pair of adjacent subcarriers do not have relative weightings +1 and -1, but satisfy a specific relationship for minimizing the interference to other narrow-band services. Simulation results show that the improved algorithms yield superior performance in terms of spectrum notch and it is found that there is no difference between our proposed algorithms and PCC method in the performance of bit error rate (BER).