Mixer mode IC design techniques for spectrum sharing

Abstract

With the development in wireless communication technique, new wireless services with high demand of frequency band resources are emerging every day. The emergence of these new services further aggregates the problem of spectral congestion in radio frequency spectrum. Spectrum sharing or dynamic spectrum access with cognitive radio, as one of the most promising solution has drawn great interest from global research resources. Spectrum sharing, as the most essential technique in cognitive radio, will fundamentally improve the spectral efficiency. Compared with conventional wireless communication services, spectrum sharing based system requires the capability of co-existence with in-band interferences before baseband ADC. Although spectrum sharing has been proved possible in code domain with direct sequence spread spectrum (DSSS) technique, this technique has two main issues to alleviate before coming into industry: spectral leakage to adjacent channel due to binary pseudo random sequence and need for accurate synchronization. This dissertation introduces the solutions to the two main problems in analog DSSS system. In the first phase of this project, a sinusoid-like pseudo random sequence based modulator/demodulator system is designed to alleviate the adjacent channel leakage issue of conventional DSSS system. In the second phase of this project, a mixed signal synchronization scheme for DSSS system is designed to accurate synchronize the received signal with the reference signal in receiver.