rocessing is implemented independently within individual coordinated base stations, based on the channel state information between the BS and the mobile stations that are served by the BS. Therefore, the Co-MIMO limits the amount of information exchange between base stations, which is different from other BS coordination approaches requiring considerable information exchange. A central scheduler, a logical functional module in the network, is responsible for coordinating a group of base stations, collecting information from the participating base stations, and determining the serving relationship between base stations and mobile stations. The overall complexity of the network operation increases with increasing numbers of coordinated base stations in Co-MIMO schemes. The Co-MIMO has the advantages of inter-cell interference reduction and spectral efficiency improvement. The inter-cell interference mitigation is realized by turning interference from neighboring cells into useful signals and separating signals for different users via multi-user MIMO or SDMA techniques. The spectral efficiency improvement is achieved via interference mitigation and the number of users supported over the same time-frequency resource region. Moreover, the Co-MIMO provides a simple approach to implementation of BS coordination and a reasonable trade-off between the performance gain, and the stringent requirement on the core network traffic and implementation complexity. In practice, the user data delivery to multiple coordinated base stations in a Co-MIMO scheme can be realized in the same manner as the multicast over backhaul is done in multicast and broadcast services. There is no additional computational complexity in base stations supporting Co-MIMO compared to the base stations which support multi-user MIMO techniques. In order to demonstrate the advantages of Co-MIMO, an example system-level simulation is conducted where the collaborative zone is defined over three neighboring sectors belonging to different BSs, as shown in Figur