Infrastructure wireless mesh network has been attracted much of attention due to a wide range of its application such as public wireless access, sensor network, etc. The application of current MAC protocols to mesh network to support transmission of multiple unicast flows reveals inefficiency in resource (time and frequency) usage. In recent years, researchers show that significant network throughput gain can be achieved by employing network coding in a wireless environment. Also, for further improvement of network throughput in one dimensional (1-D) mesh topology, it is proposed to use multiple antenna technique combined with network coding. Being inspired by MIMO network coding in 1-D topology, in this paper, the authors establish a Y-typed MIMO network coding algorithm for a tree topology consisting of two branches. In this algorithm, network coded flows of branches are spatially multiplexed. Owing to the efficient sharing of frequency of network coding and co-channel interference cancellation ability of MIMO, the proposed algorithm shows an 8-fold gain in network capacity compared to conventional methods. Furthermore, by employing freedom of antenna used at each mesh node, the authors also propose a cooperative null beamforming algorithm suppressing interference when inter-route interference is taken into account. Finally, power control is combined with the proposed algorithms for best improvement of network capacity.