System for radio transmission of digital signals between a plurality of subscriber stations and base station

DETAILED DESCRIPTION What is claimed is: 1.
A system for transmitting digital signals by radio between a plurality of subscriber stations and a base station using the so-called MC-CDMA (Multicarrier--Code Division Multiple Access) method in which a plurality of useful links are processed simultaneously in a common RF frequency band, comprising: data blocks of finite length, which can be represented by data vectors d.
sup.
(k) =(d.
sub.
1.
sup.
(k),d.
sub.
2.
sup.
(k) .
.
.
d.
sub.
N.
sup.
(k)).
sup.
T, d.
sub.
n.
sup.
(k).
epsilon.
C, k=1 .
.
.
K, n=1 .
.
.
N, K,N .
epsilon.
IN, each of the data vectors being composed of N complex data symbols d.
sub.
n.
sup.
(k) to the base m with a data symbol period length T.
sub.
s ; K subscriber stations for transmitting the data blocks with application of a spread code, assigned to a respective subscriber station k, k=1 .
.
.
K, with Q subcarriers distributed uniformly within an RF radio frequency band; a reception site using said spread code and a CDMA detector device for decoding the data blocks; a number of data symbols d.
sub.
n.
sup.
(k) transmitted simultaneously by a specific subscriber station k being one and all the data symbols d.
sub.
n.
sup.
(k) of a subscriber station being transmitted successively; said transmission using the Q subcarriers of bandwidth B.
sub.
s =B.
sub.
U /Q=1/T.
sub.
s, the subcarriers numbered with g=1 .
.
.
Q each having a single center of frequency f.
sub.
q, q=1 .
.
.
Q, in accordance with ##EQU39## each data symbol d.
sub.
n.
sup.
(k) of a subscriber station being spread over all the Q subcarriers of the bandwidth B.
sub.
s by a subscriber-specific signature code sequence c.
sup.
(k) =(c.
sub.
1.
sup.
(k), c.
sub.
2.
sup.
(k) .
.
.
c.
sub.
Q.
sup.
(k)).
sup.
T, c.
sub.
q.
sup.
(k).
epsilon.
C, k=1 .
.
.
K, q=1 .
.
.
Q, K, Q.
epsilon.
IN composed of chips c.
sub.
q.
sup.
(k), each chip being assigned to a particular subcarrier; a linearly modulated signal, which is transmitted by a subscriber station, k, k=1 .
.
.
K which is given in the equivalent low-pass filter region by ##EQU40## linear MC-CDMA spread modulation being formed by samplings of a c