METHOD AND SYSTEM FOR PERFORMING MULTIPLE ACCESS IN WIRELESS OFDM CELLULAR SYSTEMS CONSIDERING BOTH SPACE AND FREQUENCY DOMAINS

摘要

The method comprising a base station equipped with a large number of antennas according to a two-dimensional rectangular array and a number M of cell users, said rectangular array comprising N1 antenna elements along one axis with a regular spacing dx and N2 antenna elements along a perpendicular axis with a regular spacing dy, said users being characterized by angles (θ,φ) in a spherical coordinate system, where in order to achieve orthogonal multiple access the method comprises: selecting a grid spacing (Δu,Δv) in the (u, v) domain; discretizing the (u, v) domain; constructing a set of signals ST[k,l,f]; calculating time-domain excitations AT[n,m,t] for the antenna elements in the array given by coordinates (ndx,mdy) for generation of the downlink transmit signals; and obtaining the frequency contents SR[k,l,f] of the complex baseband signals received from the M users in the uplink.;The system implements the method of the invention.

主权项

1. A method for performing multiple access in wireless OFDM cellular systems considering both space and frequency domains, comprising at least one base station equipped with a large number of antennas according to a two-dimensional rectangular array and a number M of cell users, said rectangular array comprising N1 antenna elements along one axis with a regular spacing dx and N2 antenna elements along a perpendicular axis with a regular spacing dy, said cell users being characterized by angles (θ,φ) in a spherical coordinate system, characterized in that in order to achieve orthogonal multiple access the method comprises using an orthogonal space-frequency processing unit for:
selecting a grid spacing (Δu,Δv) in the (u, v) domain through the equations:Δu=λN1dxΔv=λN2dy, where λ denotes the wavelength of the system operating frequency, and the (u, v) domain is obtained from the following transformation of the spherical angles (θ,φ):
u=sin(θ)cos(φ)v=sin(θ)sin(φ); discretizing the (u, v) domain according to the following expressions:
uk=k·Δu,k=0,1, . . . ,N1−1vl=l·Δv,l=0,1, . . . ,N2−1,where the visible region of the grid corresponds to those values enclosed within a unit circle according to the equation:
u2+v2≦1; constructing a set of signals ST[k,l,f] according to the following expression:ST[k,l,f]={Si[f];∀(k,l)={(ki,li),i=0,1,…,M-1}0;otherwise,where Si[f] denote the frequency contents of the complex baseband signal aimed at user i, and (ki,li) represent the estimated user locations in the discretized (u, v) grid;
calculating the time-domain excitations AT[n,m,t] for the antenna elements in the array given by coordinates (ndx,mdy), for generation of the downlink transmit signals according to the following expression:AT[n,m,t]=1NcN1N2∑f=0Nc-1∑k=0N1-1∑l=0N2-1ST[k,l,f]exp(j2πNcft)exp(-j2πN1nk)exp(-j2πN2ml),where Nc denotes the number of subcarriers in the system bandwidth; and
obtaining the frequency contents SR[k,l,f] of the complex baseband signals received from the M users in the uplink, by applying the following transformation over a set of received signals AR[n,m,t] corresponding to each of the antenna elements:SR[k,l,f]=∑t=0Nc-1∑n=0N1-1∑m=0N2-1AR[n,m,t]exp(-j2πNcft)exp(-j2πN1nk)exp(-j2πN2ml).