Increasing Spectrum Sharing Opportunities by Radio Link Design in an Urban Environment Modern mobile communication systems like 5G require more frequency bands to achieve such user needs as higher data rate, low latency, and massive device connectivity. This paper describes our dynamic spectrumsharing scheme to obtain more bandwidth. Our scheme collects the frequency band usage information at each location and time, and determines such appropriate spectrumsharing conditions, as available spectrum band and transmission power based on the spectrum usage. If interference between the primary and secondary users occurs during spectrum sharing, the sharing condition is changed. This paper also proposes a detection method for primary user communication areas to increase the opportunity for spectrumsharing and improve the ordinally Interference Temperature Model. We conclude that spectrumsharing can be achieved in an urban radio propagation environment through a computer simulation.

A Joint Design of User Modeling and Resource Management in Cognitive Radio Networks The limited available spectrum and inefficient spectrum utilization make it necessary to employ dynamic spectrum access techniques. The key enabling technology for dynamic spectrum access is cognitive radio (CR), which exploits the existing wireless spectrum opportunistically and utilizes the licensed spectrum when primary users are passive. Thus, the activities of primary radio (PR) and cognitive radio (CR) users play a major role in the performance of cognitive radio networks. In this paper, a joint solution for user modeling and spectrum management is offered. The activities of PR and CR users are modeled through threestate Markov chain as the spectrum resource blocks are utilized with help of servicelevel overbooking strategy. Simulation results show the performance of the booking limit with respect to the channel release ratio of CR users and consequently the improved revenue of the network.