The Application Of Bridge Function Smart Codes In UWB Cognitive Radio Systems

With the developments in wireless communication technology, lack ofspectrum has become a bottleneck in the realization of high-performance dataservices. To solve the problem of spectrum scarcity and improve spectrumefficiency, cognitive radio rapidly becomes a research hotspot, which canrealize dynamic spectrum sharing through detecting spectrum withoutinterrupting the authorized user.Ultra wide band (UWB) has been one of the most appealing wirelesscommunication technologies.It can be used in high speed and short rangcommunication to aid the developing of wireless personal area network. UWBis an underlay communication technology and it is the first way in the level oftechnical and practical steps to achieve the cognitive radio. UWB is mainlyused in intensive multipath indoor channels. Multipath interference (MPI) isthe main source of interference in systems. Bridge function sequence is awidely used ternary mutual orthogonal sequence with zero auto-correlationzones (ZCZs) which can reduce multipath interference effectivelyThe non-sinusoidal orthogonal three-valued sequences–the bridgefunction sequences are introduced, including the construction with the concepts of sequence shift and sequence copying and some properties. Theconcept of Hybrid Bridge functions and their simple attributes are introducedby defining a Hybrid matrix. It is conluded that the Bridge function sequenceset and Hybrid Bridge function sequence set are complementary sets withdetailed proofs provided.A cognitive UWB radio systems using bridge function smart codesequence is proposed, the system model based on the Gaussian pulsewaveform and the bridge function smart code sequence is presented, and thesingle-user system and multi-user system are simulated, with the resultsdiscussed based on the properties of Bridge function transmission probabilityand zero correlation zone, followed by theoretical analysis.The theory of probability control has been studied. Firstly, thenon-continuous CDMA system using ternary sequences is discussed, and theimpact of transmission probability on channel capacity are discussed.Secondly, the implementation of non-continuous CDMA is introduced byusing random puncturing sequence to abort the transmission of some of theCDMA symbols. The transmission rate and the average SINR are optimizedby probability control only. Finally, the importances of probability control andsequence design with respect to transmission probability are illustrated...