Exit Chart Aided Irregular Convolutional Code Design for Iterative Downlink SDMA Systems Using Imperfect Channel State Information

We analyze a precoded and iteratively detected downhink multiuser system employing imperfect Spatio-Temporal Channel Impulse Response at the Transmitters (ST-GIRT) with the aid of Extrinsic Information Transfer (EXIT) charts. A Precoded Iterative DownLink Space Division Multiple Access (PI-DL-SDMA) system proposed in our previous research is further improved and shown to be capable of maintaining an infinites-imally low BER, despite using imperfect ST-CIRT. A further novel feature of the VPI-DL-SDMA system is that we designl an IrRegular Convolutional Code (IRCC) with the aid of EXIT chart analysis for creating an open EXIT tunnel between the inner decoder´s and outer decoder´s EXIT curve at a reduced Eb/N0 value and hence maintain an infinitesimally low BER.