1 research outputs found
Spectral Precoding for Out-of-band Power Reduction under Condition Number Constraint in OFDM-Based System
Due to the flexibility in spectrum shaping, orthogonal frequency division
multiplexing (OFDM) is a promising technique for dynamic spectrum access.
However, the out-of-band (OOB) power radiation of OFDM introduces significant
interference to the adjacent users. This problem is serious in cognitive radio
(CR) networks, which enables the secondary system to access the instantaneous
spectrum hole. Existing methods either do not effectively reduce the OOB power
leakage or introduce significant bit-error-rate (BER) performance deterioration
in the receiver. In this paper, a joint spectral precoding (JSP) scheme is
developed for OOB power reduction by the matrix operations of orthogonal
projection and singular value decomposition (SVD). We also propose an algorithm
to design the precoding matrix under receive performance constraint, which is
converted to matrix condition number constraint in practice. This method well
achieves the desirable spectrum envelope and receive performance by selecting
zero-forcing frequencies. Simulation results show that the OOB power decreases
significantly by the proposed scheme under condition number constraint