A Gaussian code division multiple access (CDMA) channel is shared by K
active users who transmit asynchronously with BPSK modulation by inde
pendent binary data streams. A conventional direct sequence CDMA recei
ver has only limited capability for suppressing cochannel multiple use
r interference (MUI) from the K - 1 other CDMA signals while attemptin
g to receive and demodulate each CDMA signal, A new and efficient feed
back receiver structure is described for coherent demodulation of the
K asynchronous CDMA signals, By incorporating adaptive cancellation of
the cochannel MUI in a feedback structure, the new design offers the
following advantages: protection of the receiver's synchronization loo
ps as well as its data demodulators against MUI; lower bit error rate
(BER) than the conventional receiver for equal-strength as well as nea
r-far MUI; and implementation simplicity close to that of the conventi
onal CDMA receiver, It is shown that all the CDMA signals are canceled
to a common level determined by N-0, the one-sided power spectral den
sity of the input AWGN; the bandwidth spreading ratio N; and K. The BE
R for any signal may be computed as if the N-0 at its matched filter i
nput were multiplied by the factor (6N/pi)(1.5N + 1 - K)) for K less t
han or equal to 1.5 N. Computer simulations corroborate this result, A
straightforward enhancement to the receiver structure is shown to all
ow it to overcome the deleterious affects of multipath propagation.