A Theory for Multiresolution Signal Decomposition: The Wavelet Representation
IEEE Transactions on Pattern Analysis and Machine Intelligence
Discrete-time signal processing
Discrete-time signal processing
Ten lectures on wavelets
Multirate systems and filter banks
Multirate systems and filter banks
Wavelets and subband coding
Wavelet packet modulation for wireless communications: Research Articles
Wireless Communications & Mobile Computing
A Review of Wavelets for Digital Wireless Communication
Wireless Personal Communications: An International Journal
Wavelet packet modulation for orthogonally multiplexedcommunication
IEEE Transactions on Signal Processing
Spectrum pooling: an innovative strategy for the enhancement of spectrum efficiency
IEEE Communications Magazine
Cognitive radio: brain-empowered wireless communications
IEEE Journal on Selected Areas in Communications
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The growing popularity of wireless applications has placed enormous burden on valuable resources such as spectral bandwidth. This has brought about a major revamp of traditional resource allocation policies culminating in an explosion of research activity in the field of cognitive radio (CR) (Mitola, Cognitive radio: an integrated agent architecture for software defined radio, Doctoral dissertation, 2000; Haykin, J Sel Areas Commun 23:201---220, 2005). In this paper we demonstrate the operation of a Wavelet Packet based multi-carrier modulation (WP-MCM) scheme in the context of cognitive radio. The wavelet packet (WP) bases are derived from multistage tree-structured paraunitary filter banks. To enable the WP-MCM cognitive radio system to co-exist with other licensed users a common spectrum pool is maintained and the WP-MCM transmission waveform characteristics are shaped to communicate in the idle time-frequency gaps of the licensed user. This is achieved by dynamically deactivating wavelet packet carriers in and near the region of the licensed user spectrum. Various wavelets including the well-known families Daubechies, Coiflet, Symlet are applied and studied. The emphasis is on the design and development of optimal WP carriers that have narrow and well confined spectral footprints. To this end filter banks that are maximally frequency selective are derived through a modified Remez exchange algorithm. Through simulation results the ability of the proposed wavelet packet based mechanism in seamlessly cohabiting with licensed users is demonstrated. The Bit Error rate (BER) performance is shown to be comparable, and even at times better, to the conventional Fourier based OFDM system.