Design Of Wideband Millimeter-wave Transmission Scheme Based On Squint Multi-beam

Wideband millimeter-wave(mm Wave)is one of the important problems and bottlenecks encountered in mm Wave communication technology in the recent years.The beam squinting problem of wideband mm Wave antenna array has gradually started to attract academic attention in the last few years.In this thesis,we mainly study the design of ultra-wideband mm Wave frequency squint multi-beam planar array transmission scheme,the design of wideband mm Wave frequency squint multi-beam subarray collaborative transmission scheme,the design of wideband mm Wave frequency squint multi-beam linear array transmission scheme,and the design of power-domain NOMA algorithm for wideband mm Wave linear array.The detailed contents and main contributions of this thesis are listed as follows.1.By exploiting the beam squint property brought by the ideal phase shifter group to the antenna array,a scheme using broadband frequency squint multi-beam to serve multi-user for mm Wave cellular communication system is designed as one of the possible solutions to the beam squint problem in the ultra-wideband mm Wave scenario for digital-analog hybrid structures.First,a compact ultra-wideband multi-tier array structure supporting squint multi-beam is designed using the Sierpinski carpet topology.Second,the number of phase shifters and the number of cells in the phase shifter are reduced by using a tandem group of phase shifters to simulate all phase shifters in each planar array tier;when the subarrays are used,we avoid adding more phase-shifting units to the subarrays by compensating the phase deviation between the subarrays in the digital domain,so that the larger array can reuse the existing subarrays,and we reveal that regardless of the type of phase-shifting cells used,this planar array cannot cover all internal angles of space by squint beams alone.Then,the algorithm demonstrates the selection of the phase shifting units of the virtual phase shifter and the selection of the operating frequency of squint beams for each user for practical situation.Finally,a wideband channel representation supporting frequency squint beams is given,and the feasibility of the proposed scheme is verified by simulation experiments.2.To address the problem that the constraint of the horizontal azimuth ? of the squint beams in the planar array with the ideal phase shifter restricts the system to serve more users,a beam-domain precoding-based subarray collaborative squint multi-beam transmission scheme is designed in a line-of-sight multi-user downlink scenario with multiple subarrays at the base station end.First,the beam domain partitioning at the center frequency isgiven,and it is shown that the uniform quantization of phase shifters and the beam domain precoding scheme are compatible.Second,the squint grouping method in the subarray elevation direction is given,and the problem of maximizing the number of users served in the system is presented.Then,a suboptimal algorithm is given which gradually shrinks the set of serviceable beams of subarrays in the beam domain space in iterations.Finally,the feasibility of the proposed scheme and the performance of the proposed suboptimal algorithm are verified by simulation experiments.3.To address the problem that the constraint of the horizontal azimuth ? of the squint beams in the planar array with the ideal phase shifter restricts the system to serve more users,a squint multi-beam scheme is designed to circumvent this constraint with the linear array.First,to address the problem of mismatch between the array response of linear array and express of the actual channel path when using linear arrays in 3D scenarios,we propose a scheme using multi-beam of a virtual planar array to simulate the actual ring beam of the linear array.Next,the conditions of no gate lobes and only one gate lobe are given for the wideband linear array.Then,the squint multi-beam algorithm is designed to serve multi-user in the scenario of using a linear wideband phased array at the base station end.Finally,the feasibility of the proposed scheme is verified by simulation experiments.4.For the scenario of a linear array with scatterers of multi-user on a single ring beam,the power-domain NOMA algorithm with squint beams is designed to serve more users simultaneously.First,the two-user NOMA sum rate maximization problems for the scenario in question are studied,and the feasible interval of power-domain NOMA in the two-user channel is given.Second,in order to support as many users as possible in the ring beam without adding additional beams,a NOMA algorithm for users in the main beam ring is designed.Then,a NOMA algorithm is designed to pair users in the main beam direction with users in the first side lobe direction,where the first sidelobe direction of the squint beam points to the poor channel quality user in the NOMA pair,and the best channel quality user in the NOMA pair is in the HPBW corresponding to the main direction of the squint beam.Finally,the performance of the proposed algorithm is verified by simulation experiments.