Positioning Receiver In Frequency Division Duplex System

With the emergence of the fifth generation communications,the spectrum resource is becoming shorter and shorter.To deal with the issue,mobile operators have to improve the spectrum efficiency.Cognitive radio is a promising technique to enhance the spectrum efficiency through spectrum sharing.In a cognitive radio network,cognitive users are allowed to use the primary frequency bands for cognitive communications.Nevertheless,each cognitive transmitter has to control the interference to the corresponding primary receiver.When primary transceivers work in the Time Division Duplex(TDD)mode,the cognitive transmitter can obtain the interference channel through the channel reciprocity so as to control the interference.When primary transceivers work in the Frequency Division Duplex(FDD)mode,the cognitive transmitter has to position the primary receiver for the interference management.We assume that primary transceivers work in FDD mode,and study the positioning problem of the primary receiver.In particular,we consider both line-of-sight and non-line-of-sight scenarios and develop passive receiver positioning methods,respectively.We consider that primary transceivers adopt the closed-loop power control,which means that the primary transmitter automatically adjusts the transmit power to meet the target signal to noise ratio at the primary receiver.Then,the transmit power of the primary transmitter contains some information of primary receiver's position.Thus,the cognitive transmitter can learn the position information from the primary signal.The contributions and novelties of this thesis are listed as follows:Firstly,we consider the line-of-sight scenario,and propose a Maximum Likelihood(ML)criterion positioning algorithm as well as a Median-based(MB)positioning algorithm.In particular,we elaborate the basic principle and derivations of both algorithms,and obtain the distance between the primary transceivers with a closed-form expression.Then,we use the simulation results to show the feasibility of the two positioning approaches.Secondly,we consider the non-line-of-sight scenario,propose a MB positioning algorithm as well as a Mean-value-based(MVB)positioning algorithm.Meanwhile,we utilize the estimated position information of the primary receiver to design the access probability of cognitive transmitter for spectrum sharing.Furthermore,the simulation results demonstrate the positioning performance and the access performance.