| With the development of wireless communication and the significant growth of mobile data traffic,wireless devices are increasingly demanding data transmission rates.The traditional 2.4 GHz and 5 GHz microwave band spectrum resources are already scarce,and it is difficult to meet the current demand.The 60 GHz millimeter wave has huge bandwidth and can meet many high transmission rate applications,making it a research hotspot for academia,industry and standardization organizations.However,in 60 GHz millimeter wave communication,the millimeter wave has a short transmission distance and a large path loss,so directional transmission is often used to make up for these deficiencies,which provides the possibility for spatial reuse.In recent years,due to the increasing demand for users in dense users' scenarios such as airports,conference rooms,stadiums and libraries,the access point(AP)will also be densely arranged,and the coverage of each BSS will overlap.Although the millimeter-wave directional beam itself has the effect of spatial isolation and spatial reuse,in a user-intensive scenario,interference may occur between communication links in different BSSs.In summary,how to reduce inter-network interference and improve the spatial reuse capability of the system in dense users' scenarios has become the focus of research.Therefore,this thesis will study the spatial reuse of millimeter-wave beam links in these cases.Firstly,in the dense BSS network scenario,this thesis proposes a centralized beamforming training scheme coordinated by the centralized controller AP(Controller-AP,C-AP).The scheme combines interference measurement and beamforming training,and collects beam information of each link and interference information of the link in the process of beam training.After the beam training,the respective beam training information and the collected other link interference information are reported to the C-AP,so that the C-AP can perform effective scheduling resources and lay a certain foundation for the spatial reuse technology.Secondly,this thesis studies the spatial reuse scheme between networks based on the protocol interference model in the centralized network architecture.In this scheme,the beam information table is first established according to the beam information of the STA collected by the C-AP in the centralized beamforming training process.Then we propose a decision condition that uses the optimal beam difference value as a coexistence of the two links.Then,in order to realize simultaneous transmission of multiple links between different BSSs,the C-AP performs spatial reuse scheduling according to the beam information table and the optimal beam difference.Finally,the proposed scheme is compared with the MSND scheme through simulation.The simulation results show that the proposed scheme can improve the spatial reuse gain.Finally,this thesis studies the spatial reuse scheme between networks based on physical interference model in centralized network architecture.In the scheme,the C-AP firstly establishes a link interference information table according to the interference information collected in the centralized beamforming training process,which avoids the time overhead caused by the directional measurement in spatial reuse.Then,the conditions for the coexistence of the links are analyzed.Then,the link scheduling algorithm between the BSSs is proposed by using the link interference information table and the decision conditions of the link coexistence.Finally,the performance of the proposed spatial reuse scheme is studied by simulation.The simulation results show that the proposed scheme has higher spatial reuse gain and higher system throughput than those of the random scheduling scheme and the distributed scheduling scheme. |
