A method and system for multiple access in a system utilizing two-dimensional signal modulation. The method includes spreading data symbols arranged in a two-dimensional information domain onto sets of grid points respectively associated with different users in a time-frequency domain. The spreading is performed using two-dimensional basis functions uniquely associated with positions on a lattice in the information domain corresponding to the data symbols. A modulated signal is then generated using the sets of transformed symbols. The sets of grid points associated with the different users may be interleaved within the time-frequency domain or may form non-interleaved windows.