Research On Resource Allocation Scheme Based On LAA To NR-U Evolution

Due to the scarcity of spectrum resources,telecom operators hope to offload 4G and 5G services to unlicensed spectrum to reduce the load on the licensed spectrum network.LAA(Licensed Assisted Access)and NR-U(New Radio-Unlicensed)are main technologies used by 4G and 5G in unlicensed spectrum,respectively.Because the LAA system adopts a contention-based channel access mechanism and dynamic discontinuous transmission in the unlicensed spectrum,its resource utilization in the unlicensed spectrum is insufficient.The NR-U uses the same channel access mechanism,so the same drawbacks may exist.How to realize the effective use of unlicensed spectrum resources in the LAA to NR-U evolution process has become an urgent problem to be solved.In order to solve the above problem,this thesis proposes three resource allocation schemes for unlicensed spectrum.From the perspective of time domain resource allocation,solutions for NR-U system and LAA system are designed respectively.For the NR-U system,this paper proposes a resource allocation scheme based on the NR frame structure.By adopting configurable subcarrier spacing or mini-slot,the useless padding of the unlicensed spectrum is reduced,and the NR-U system realized full utilization of time domain resources in the unlicensed spectrum.For the LAA system,this thesis proposes a resource allocation scheme based on TTI(Transmission Time Interval),which studies the cell reference signal and shortened transmission time interval,and solves the problem of low resource utilization in the LAA system.In terms of frequency domain resource allocation,a sub-band based resource allocation scheme is designed.By dividing the resource mapping of large bandwidth into multiple sub-bands,a more efficient transmission of large bandwidth in the unlicensed frequency band is realized.Finally,this thesis evaluates the system performance of the above resource allocation scheme through system level simulation.The simulation results show that the resource allocation scheme based on NR frame structure can effectively improve the performance of NR-U system and realize the friendly coexistence of NR-U system and Wi-Fi system.The TTI-based resource allocation scheme can improve the throughput of small data packet transmission in the LAA system,reduce the delay and improve the resource utilization of the unlicensed spectum.The sub-band based resource allocation scheme can increase the access opportunity of large bandwidth in the unlicensed spectrum,thereby improving the user experience.