The Performance Analysis Of Cognitive Multipoint Communication Systems

Cognitive radio(CR)is considered to be a promising method which effectively employs spare spectrum and solves the insufficiency of the wireless spectrum.The capacity research hot of spectrum sharing CR includes the following two types,such as the capacity of basic model and the capacity of spectrum sharing multipoint model.At present,the spectrum sharing CR capacity research of the basic model is very mature,however,the capacity performance of the spectrum sharing CR multipoint communication model has not been fully studied.The main contents of the dissertation include the following aspects:Firstly,the average capacity of the multicast scheme in spectrum sharing CR is the interference temperature,which is nothing to do with peak transmission power of secondary base station.Then we derive the multicast capacity of secondary base station with multiple antennas,and analyze the relationship between the capacity with the number of antennas and the number of secondary users and interference temperature.Secondly,for a spectrum sharing CR multiuser access channel,we analyze the asymptotic capacity by considering an arbitrary peak power at the secondary transmitter and the interference from the primary transmitter based on extreme value theory.The scaling law of our capacity is found to be double logarithm of the number of secondary users.Thirdly,we address the transmission capacity of a two spectrum sharing CR Ad hoc networks with multiple antennas.Based on stochastic geometry tool and Markov's inequality,we first derive bound on the transmission capacity for the primary networks,then the transmission capacity of the secondary networks is derived when the transmission density of primary network maintains unchanged.Using the obtained bounds,we derive their optimal number of data streams to transmit and the optimal spatial receive degrees of freedom to use for interference cancelation.Fourthly,this dissertation analyze the throughput of random beamforming(RBF)for a multi-antenna CR broadcast network.Using extreme value theory,the asymptotic average throughput of a single-beam RBF and a multiple-beam RBF are derived from the limiting distribution of the sample maximum of received signal-to-noise ratio(signal-to-interference-plus-noise ratio)with maximal ratio combiner at the secondary user.In addition,this dissertation also studies the other performance of CR broadcast channel(outage probability,moment generating function and symbol error rate),where both peak transmit power constraint and peak interference power constraint at the SBS are considered.Next,cooperative communication has been considered as an effective way to utilize the spatial diversity and expand the communication range.In CR cooperative communication,cognitive relay nodes can amplify and forward the received signal to the destination or retransmit for decoding of the received signal by decoding forwarding protocol.Then,the performance of CR cooperative communication system is analyzed in this dissertation.Finally,a conclusion is drawn for the dissertation,and valuable research directions in the future are discussed.