Research On Joint Transmission Of Distributed Antenna Cells

Future mobile communication system is considered to be a interference-limited system. Joint transmission (JT) has been discussed in this thesis to mitigate the inter-cell interference (ICI). Precoding can achieve JT by pre-process the multi-user signals before transmitting with its focus on the precoder design according to the channel state information at transmitter (CSIT).This thesis start from the MIMO theory such as diversity gain,multiplexing gain,channel model and channel capacity. The simulation of MIMO ergodic capacity and influence of channel correlation on capacity under different antenna configuration has been led.In the next section, single-user and multi-user precoding has been researched. In single user scenario, ZF,MMSE and SVD precoding technology is reviewed with simulation of ZF and MMSE precodings on bit error rate (BER). Grassmannian pecoding based on the codebook is studied with an introduction to application in the LTE system. In multi-user scenario, ZF,MMSE and BD precoding technologies are discussed in the linear section with simulation of the BD channel capacity under correlated condition and non-correlated channel condition. ZF THP and MMSE THP precodings are simulatedin the non-linear section. The result of simulation indicates that both of the single-user and multi-user precoding can improve the capacity or decrease the BER.Following the previous discussion, three JT schemes based on the relay node are studied. In the 1-1-N (one base station, one relay node, N users) system, two different transmission schemes have been researched with simulation of BER of the two schemes under different precodings. In the N-1-N system, precoding is led at relay node to detect the signals transmitted from different base stations and mitigate the multi-user interference. Simulation of the capacity of this scheme,ZF-relay capacity,non-relay capacity has been conducted. In the N-N-N system, simulation of system ergodic capacity has been led under different number of relay nodes.