Research On User Pairing Algorithms Of The Virtual MIMO System In LTE Uplink

People’s demand for high transmission rate of wireless communication system is rising day by day. It is very important to make full use of the limited time-frequency resource to achieve higher transmission rate. MIMO technique can improve communication system capacity and spectral efficiency significantly, which has been adopted by multiple wireless communication standards.However, user equipments usually have only a transmitting antenna because of the restrictions on volume and power. It is inconvenient to adopt MIMO technology to increase data transmission rate in LTE uplink. To solve this problem, virtual MIMO technique pairs multiple user equipments to construct a virtual MIMO system. And these can be served simultaneously on the same radio resource unit to improve spectral efficiency and system throughput without upgraded hardware specifications.In virtual MIMO system, user pairing algorithm directly affects system performance. This thesis focuses on user pairing algorithm of virtual MIMO system in LTE uplink, and does several exploratory researches. It consists of the following three aspects:First, the LTE uplink system level simulation platform is established. Combined with LTE uplink system model and related 3GPP protocols, this thesis gives the simulation modeling of LTE uplink system, and provides basic for user pairing algorithm’s performance verification.Second, three user pairing algorithms of virtual MIMO system under symmetric resources are proposed. Greedy multiuser pairing algorithm selects individual pairing user at once, and aims to approach as much system throughput as possible with realizable computational complexity. Then, its simplified algorithm just needs to calculate the 2-order determinant, and further reduces the computational complexity. Futhermore, the simplified greedy proportional fair algorithm combines proportional fair criteria and the simplified algorithm. Simulation results show that, in LTE uplink under the conditions of four users pairing, each cell containing 40 users, compared with the D-PF algorithm, the simplified greedy proportional fair algorithm increases the cell edge throughput and cell average throughput by 116.67% and 13.41%, respectively.Third, two user pairing algorithms in virtual MIMO system under asymmetric resources are proposed. Partial asymmetric algorithm divides frequency resources to several part based on scheduled users’ RB occupancy. Then, it selects users to occupy the the beginning of each part RBs. Completely asymmetric algorithm does take no account of the scheduled users’ RB occupancy, and selects pairing users based on proportional fair criterion. Simulation results show that, in LTE uplink under the conditions of two users pairing, each cell containing 40 users, compared with the D-PF algorithm, two proposed algorithms increases the cell edge throughput by 236.73% and 256.79% respectively, and improves the cell average throughput by 40.70% and 47.38% respectively.This thesis focuses on user pairing algorithm in virtual MIMO system of LTE uplink and proposes greedy algorithm, simplified algorithm, simplified greedy proportional fair algorithm under symmetric resources and partial asymmetric algorithm, completely asymmetric algorithm under asymmetric resources. These proposed algorithms can be applied to LTE, LTE-A and other communication system using the virtual MIMO technique, which increase spectrum efficiency, system capacity and improve communication quality.