Performance Research On Cross-layer Design Of Heterogeneous Multiuser MIMO Systems Under Spatial Correlated Channel

Multiple input multiple output(MIMO) technique can greatly improve the link robustness, system capacity and spectrum efficiency, thus received widely attention. Compared with single user MIMO, the multiuser MIMO can take full advantage of multiuser diversity gain and multiplexing gain, further improve the spectrum utilization efficiency and reliability of the whole system. Cross-layer design(CLD) coordinated information interaction between the layers through the network, so as to realize the reasonable and effective allocation of network resources. Therefore, by combining adaptive modulation(AM) at the physical layer and automatic repeat request(ARQ) at the data link layer, the CLD scheme for multiuser MIMO system is presented. In this thesis, considering the statistics of users are non-identically distributed, as well as the spatial correlation exists at the transmit end, the performance on CLD of heterogeneous multiuser MIMO system based on imperfect channel estimation is studied in order to provide necessary theoretical basis for the practicability of CLD. The main contents of the thesis are summarized as follows:1. The CLD based on the fair scheduling in heterogeneous multiuser MIMO system is investigated. In actual communication, due to the statistical features of the signal-to-noise ratio of users are not identically distributed, the traditional scheduling cannot guarantee the equality between users. Therefore, a CLD scheme for multiuser MIMO system which combined with transmit antenna selection, adaptive modulation, automatic repeat request and proportional fair scheduler(PFS) is proposed. This scheme can take full advantage of multiuser diversity to improve the system performance while ensure all users in a cell can be fair scheduled.2. The CLD in heterogeneous multiuser MIMO system under spatial correlation channel is studied. In the actual wireless communication environment, due to restriction on the size of transmit antenna or poorly scattering environment, the MIMO channel are no longer independent of each other, but there exist spatial correlation at the transmit side. Based on this, we put forward to study the performance of CLD in heterogeneous multiuser MIMO system under spatial correlation channel. Furthermore, the simulation results verify the effectiveness of the theoretical analysis.3. The CLD based on imperfect channel estimation information in heterogeneous multiuser MIMO system is investigated. In view of the instability of information feedback link or channel estimation error, the information at the receiving end is imperfect. Thus, the CLD scheme in heterogeneous multiuser MIMO system with spatial correlation is proposed based on imperfect channel state information(CSI), the average spectral efficiency(ASE) and packet error rate(PER) of the system are respectively calculated in order to evaluate the performance in theory.