Patent ID: 8565175

Claim:
A method for use in a multiple-input multiple-output wireless communication system in which: a plurality of base stations are provided each of which can transmit signals to, and receive signals transmitted from, one or more user equipments; the base stations are organized into a plurality of groups; in a given group of base stations serving one or more user equipments, those serving base stations coordinate with each other to simultaneously transmit signals to the one or more served user equipments, and one or more of the served user equipments feed back information to one or more of those serving base stations, wherein said information incorporates inter-group noise information related to interference between different base station groups, the method comprising: processing signals for simultaneous transmission from base stations of a group of the plurality of groups to one or more user equipments served by that group, said processing using the inter-group noise information fed back to the base station(s) of that group to improve transmission capacity, wherein a noise-related parameter is defined which incorporates the inter-group noise information which, includes noise power Ĩ 0 which represents the component of the total power of the noise in the system that is associated with inter-group interference, the processing involves using the noise-related parameter to precode signals for simultaneous transmission from base stations of a group to one or more user equipments served by that group, information fed back by the one or more of the served user equipments further includes noise power Ñ 0 which represents the component of the total power of the noise in the system that is associated with background noise, the noise-related parameter, μ, is calculated using an equation equivalent to the following: μ = I ~ 0 + N ~ 0 p _ k ⁢ β where p k represents the mean transmit power of transmitting antennas of the base stations of the group and β represents a parameter that can be varied to give the value of μ which enables the precoding to yield a high improvement in system performance, N B represents the number of base stations in a group, N U represents the number of user equipments served by the base stations of that group in a given time slot, N R represents the number of antennas on each user equipment, N T represents the number of transmitter antennas on each base station in the group, and a channel between the base stations of the group and the user equipments served by the group is represented by a channel matrix HεC N R N U ×N T N B , and the precoding of signals for simultaneous transmission from the base stations of the group to one or more user equipments served by the group involves calculating a precoding matrix F using an equation equivalent to the following: F=H H ( HH H +μI ) −1 .