In this paper

based on blind adaptive gradient algorithm (BAG) for multiuser detection

an improved blind adaptive gradient algorithm (IBAG) for code-aided suppression of multiple-access interference (MAI) and narrow-band interference (NBI) in direct-sequence code-division multiple-access system is proposed.The blind adaptive gradient algorithm (BAG) has two types:tracking blind adaptive gradient algorithm (TBAG)

which has the tracking ability

and time-invariant blind adaptive gradient algorithm (TIBAG)

which is applied in time-invariant circumstances.TIBAG has good constringency but no tracking ability

while TBAG has good tracking ability but its SIR rises slowly at beginning.so

IBAG modifies TIBAG to make its SIR riss more quickly and to keep its tracking abilty as time goes on.The simulation results show that the IBAG has the similar computational complexity to BAG

but the tracking ability and convergence performance of the IBAG is much better than the BAG.