Large-scale MIMO satellite mobile communication method and system

Abstract: The invention discloses a large-scale MIMO satellite mobile communication downlink transmission method and a large-scale MIMO satellite mobile communication downlink transmission system with maximum reachability and rate. A satellite or a gateway station calculates a precoding vector corresponding to each user terminal through an iterative algorithm by using statistical channel information of eachuser terminal according to traversal reachability and rates of all users or an upper bound maximization criterion of all the users; downlink precoding transmission is carried out by using the obtained vector. According to the iterative algorithm, a precoding vector design problem is converted into a multi-times convex optimization sub-problem, a precoding vector is obtained by iteratively solvingthe convex optimization sub-problem, or the convex optimization sub-problem is converted into a Lagrange multiplier optimization problem, a Lagrange multiplier is iteratively solved, and then the precoding vector is calculated. And the user terminal performs frequency and time compensation on a received signal by utilizing Doppler frequency shift caused by satellite movement and minimum propagation time delay of long-distance propagation. According to the invention, the reachability and rate performance of a satellite mobile communication system can be improved, and the calculation complexityis relatively low.

Abstract: The invention discloses a multi-beam high-throughput satellite communication system based on MIMO and an implementation method thereof. The satellite system comprises a plurality of gateway stations,the gateway stations are bidirectionally connected to satellites through feeder line links, the satellites are bidirectionally connected to user terminals through user links, the information interaction path comprises that the gateway stations are transmitted to the user terminals through the satellites and the user terminals are transmitted to the gateway stations through the satellites, and thegateway stations are connected to a core network; feed multi-beam bands of a plurality of gateway stations are aggregated, the required bandwidth is increased by utilizing frequency multiplexing, high-throughput satellite communication is realized by utilizing a multipoint beam structure, and higher service flexibility is achieved.

Abstract: An embodiment of the invention provides a star-sky-ground cooperative ocean communication network capacity optimization method and device. The method comprises the following steps of constructing an optimization problem model based on a large-scale fading channel between a shore-based base station of each offshore cell, an unmanned aerial vehicle and an offshore terminal, and a large-scale fadingchannel between a shore-based base station of each offshore cell, the unmanned aerial vehicle and the offshore terminal on the premise of ensuring that interference borne by the offshore terminal is smaller than a preset value, wherein the optimization problem model aims to maximize the total rate of all offshore cells; calculating an optimal solution of the optimization problem model, and determining the transmitting power of the base station of each offshore cell according to the optimal solution. According to the star-sky-ground cooperative ocean communication network capacity optimizationmethod and device provided by the embodiment of the invention, under a sea area communication scene, the interference to ocean satellite users is controlled by optimally allocating the power of the offshore cell unmanned aerial vehicle and the shore-based base station, the transmission rate of the offshore cell is maximized, and the performance of a star-sky-ground cooperative network is improved.

Abstract: The invention provides a large-scale multiple-input multiple-output (MIMO) underwater acoustic communication method and a large-scale MIMO underwater acoustic communication system. A transmitting endor a receiving end is provided with a large-scale transducer array, and the transmitting end carries out the low-complexity precoding matrix design through the statistical channel information of a beam domain and the sparse characteristics of an underwater acoustic channel, wherein the low-dimension precoding design based on deterministic equivalence is suitable for the situation that the transmitting end or the receiving end is provided with the large-scale array. Particularly, when the transmitting end is configured with dozens of transmitting transducers, a precoding matrix can be obtainedthrough beam domain power distribution. And when both the transmitting end and the receiving end are provided with dozens of transducers, the optimal beam domain power distribution can be realized through a classical water injection algorithm. According to the method provided by the invention, the spectral efficiency and the power efficiency of underwater acoustic communication can be remarkably improved, so that the transmission rate and the transmission distance are greatly improved, and meanwhile, the problem that the related precoding design is complex is solved.

Abstract: The invention provides a low-complexity large-scale MIMO downlink precoding method in a low-orbit satellite communication system, a large-scale uniform planar antenna array is configured on a satellite side, a satellite groups users by using space angle information of each user, and the users in the same group are scheduled to use the same time-frequency resource to perform wireless communicationwith the satellite. A downlink precoding vector of each user is calculated by utilizing the statistical channel state information at the satellite side. Based on a truncated Taylor polynomial expansion theory, complex large-dimension matrix inversion operation in a downlink precoding vector is replaced by the sum of finite term matrix polynomials, so that the calculation complexity of the precoding vector is reduced. A matrix polynomial is iteratively calculated by adopting a Horner algorithm in calculation, so that the calculation complexity of the matrix polynomial is reduced. The final sumrate performance of the method provided by the invention can effectively approach the performance of downlink maximum signal-to-leakage-and-noise ratio precoding at a low expansion order.

Abstract: We investigate robust multigroup multicast transmission for frame-based multi-beam satellite communication systems with full frequency reuse. To mitigate the effect of outdated channel state information (CSI), we first investigate robust multigroup multicast precoding that maximizes the minimum average signal to interference plus noise ratio (SINR) under the per-beam power constraints. We show the relationship between the robust max–min fair problem and the robust power minimization problem with partial CSI and propose a low complexity precoder for the robust power minimization problem. We then investigate user clustering which only requires partial CSI. We show that the approximated average SINR can be maximized provided that the estimated channel vectors of the users in the same cluster are linearly dependent while those in different clusters are mutually orthogonal. Motivated by this user clustering condition, we further propose a low-complexity user clustering algorithm. Simulation results demonstrate that the proposed robust approach can provide substantial performance gains over the conventional approach in multi-beam satellite communication systems.

Abstract: The invention discloses a multi-user beam-forming method and device which are applicable to the MIMO wireless communication system based on TDD. In the scheme of the invention, the downlink channel information of each user is obtained according to uplink channel information, the DOA estimation algorithm is adopted to obtain the DOA information of each user according to the downlink channel information; and the users are paired, the users satisfying set constraint conditions constitute a paired user group, the null widening algorithm is adopted to calculate the weight of beam of each user according to the DOA information of each user in the paired user group; and the beam corresponding to the weight of beam of each user has the following properties: main lobe is generated in the corresponding DOA direction of each user, and broad-range nulls are generated in the DOA directions of other users in the paired user group. Only multi-antenna technology and beam null widening technology are used under the condition of not using codes so that at least two users can use the same time, frequency and code resources and the effective reuse of system resources can be realized.

Abstract: A WTRU may include a memory and a processor. The processor may be configured to receive beam grouping information from a gNB or transmission and reception point (TRP). The beam grouping information may indicate a group of beams that the WTRU may report using group-based reporting. The group-based reporting may be a reduced level of reporting compared to a beam-based reporting. The group-based report may include measurement information for a representative beam. The representative beam may be one of the beams in the group or represents an average of the beams in the group. Alternatively, the representative beam may be a beam that has a maximum measurement value compared to other beams in the group. The group-based report may include a reference signal received power (RSRP) for the representative beam and a differential RSRP for each additional beamin the beam group.

Abstract: The invention provides a multiuser channel estimating and tracking method for a large-scale MIMO system. The multiuser channel estimating and tracking method comprises step 1, obtaining downlink user space channel information and space angle information through a downlink preamble frame pilot sequence; step 2, grouping downlink users according to the downlink user space channel information and the space angle information of the downlink users; and step 3, carrying out channel estimation and feedback according to the grouping condition of the downlink channel users. According to the multiuser channel estimating and tracking method for the large-scale MIMO system provided by the invention, no synchronization between the users is needed, and more user terminals can be served. Moreover, the downlink training pilot cost can be reduced, and the application of the FDD in the large-scale MIMO communication system is promoted; and the implementation complexity of the system is reduced, and the channel estimation precision in a time varying condition improved.