A base station belonging to one of plural cells using a same portion of a system bandwidth, comprising: a part configured to determine which user apparatus among the user apparatuses existing in a service area should be assigned one or more resource block units of a matrix having a time axis and a frequency axis, the resource block unit having a predetermined bandwidth in the matrix and a predetermined time period in the matrix and being identified by a shared resource number shared by the plural cells; a part configured to grade the plural user apparatuses based on a wireless propagation quality status of each of the plural user apparatuses and determine ranking numbers corresponding to the plural user apparatuses; a part (108, 102) configured to generate assignment information indicating which of the plural user apparatus should be assigned to which of the resource block units according to a predetermined corresponding relationship between the shared resource number and the ranking number, wherein the ranking numbers represent the order of the relative quality of the wireless propagation quality status of each of the plural user apparatuses relative to each other, and wherein the ranking numbers are associated to corresponding shared resource numbers, the assignment information allowing user apparatuses from among the plural user apparatuses having relatively poor wireless propagation quality to be prevented from simultaneously using the same frequency; and a part configured to report the assignment information to the corresponding plural user apparatuses; wherein the predetermined corresponding relationship is determined to be different among the plural cells using the same frequency bandwidth. a part configured to determine which user apparatus among the user apparatuses existing in a service area should be assigned one or more resource block units of a matrix having a time axis and a frequency axis, the resource block unit having a predetermined bandwidth in the matrix and a predetermined time period in the matrix and being identified by a shared resource number shared by the plural cells; a part configured to grade the plural user apparatuses based on a wireless propagation quality status of each of the plural user apparatuses and determine ranking numbers corresponding to the plural user apparatuses; a part (108, 102) configured to generate assignment information indicating which of the plural user apparatus should be assigned to which of the resource block units according to a predetermined corresponding relationship between the shared resource number and the ranking number, wherein the ranking numbers represent the order of the relative quality of the wireless propagation quality status of each of the plural user apparatuses relative to each other, and wherein the ranking numbers are associated to corresponding shared resource numbers, the assignment information allowing user apparatuses from among the plural user apparatuses having relatively poor wireless propagation quality to be prevented from simultaneously using the same frequency; and a part configured to report the assignment information to the corresponding plural user apparatuses; wherein the predetermined corresponding relationship is determined to be different among the plural cells using the same frequency bandwidth.