Beam Management Scheme In Millimeter Wave Communications

With the popularity of Internet and smart devices,mobile data traffic is experiencing an explosive growth,and the expectation of data rate rises to multi-gigabits.However,the conventional microwave spectrum resources have been crowded and they cannot meet the growth of mobile data traffic and the requirement of high transmission rate.To address this issue,millimeter wave(mmWave)spectrum operating in about 30 GHz~300 GHz bands have attracted increasing attention.Moreover,due to the huge unlicensed bandwidth(up to10 GHz),60 GHz band has greatly attracted the interest of academia,industries and standardized organizations.With the advantage of large bandwidth,mmWave communication in 60 GHz band can satisfy numerous high-data-rate demand applications,such as high definition uncompressed video stream,3D game and high definition video call.On the one hand,60 GHz mm Wave communication suffers from severe transmission path loss,and it generally uses directional beamforming technology to compensate the path loss.However,comparing with microwave communication,mmWave communication introduces extra overhead of beamforming and beam link maintenance.On the other hand,large path loss and directionality can be used to enhance spatial reuse and increase system throughput.However,transmission links may interfere mutually in dense mmWave networks and affect spatial reuse.Therefore,efficient beam management and beam link scheduling are very important in improving 60 GHz mmWave system performance.In this context,we will focus our study on mmWave beam management and beam link scheduling in dense mmWave networks.Firstly,we investigate beam management scheme in mmWave communication.Considering the drawback of beam management strategy in IEEE 802.11 ad,we propose the concept of beam group management and give two beam group management solutions:Tx-beam based uniform grouping and Tx-beam based non-uniform grouping.In uniform grouping,groups are divided with uniform SNR(Signal-to-Noise Ratio)space.Tx beams will be allocated to groups according to its SNR value.In non-uniform grouping,groups are divided with non-uniform SNR space and,meanwhile,Tx-beams with smaller SNR values have larger grouping space and Tx-beams with larger SNR values have smaller grouping space.The simulation results show that grouping based beam management scheme can reduce signaling and feedback overhead,and can reduce the complexity of beam management at the same time.Secondly,we investigate transmission link scheduling and spatial reuse scheme in dense mmWave networks.To coordinate the transmission of links belonging to different BSSs(Basic Service Set),we adopt an mmWave network architecture based on centralized control.The link scheduling and transmission in the network utilize frame based method,in which the centralized controller collects users' transmission demand and makes a schedule,and then links start data transmission.To mitigate transmission interference and collision and to fully utilize spatial reuse,we propose an optimal scheduling model with the goal of minimizing scheduling time.To reduce the complexity of optimal scheduling and make a practical scheduling,we propose a Multiple-BSS Coordinated scheduling Medium Access Control(MBCSMAC)scheme.In this scheme,we design a multiple link concurrentscheduling algorithm to fully exploit spatial reuse.Moreover,we compare the performance of MBCSMAC with time division scheduling scheme and random scheduling scheme.The results show that MBCSMAC can reduce scheduling time effectively and can increase system throughput largely.