The robustness to jamming signal is an important property for military communication systems. Some previous work has shown that the frequency domain code division multiplexing (CDM) efficiently rejects the interference. In general, however, the jamming signal has higher power than ordinary interference which leads to insufficient jamming rejection performance of these schemes. To mitigate this insufficiency, we propose optimal receiver structures in mean sqaure error (MSE) sense in the presence of narrow-band jamming signal. Also these receivers are extended to iterative regime. By this approach, high power narrowband jamming signal could be efficiently rejected.