A multiuser interference cancellation technique utilizing convolutional codes and orthogonal multicarrier modulation for wireless indoor communications

This paper suggests that multicarrier modulation reduces the complexity and the delay caused by the multiuser interference cancellation process utilizing convolutional codes. For spread spectrum multiple access, multiuser interference (interference due to signals from other users) limits the performance of the communication link. To remove this interference, a multiuser interference cancellation technique which utilizes orthogonal convolutional codes has been proposed for the uplink (mobiles to a base station) of the cellular code-division multiple-access (CDMA) systems. However, this technique requires the large interleavers and the huge memory, or the artificial multipath diversity and the RAKE system to achieve sufficient coding gain if it is applied for wireless indoor communications and fading is slow compared to the data rate. To reduce the complexity of the canceller, multicarrier modulation is employed as it provides frequency diversity gain and coding gain without the interleavers or the RAKE system. This paper shows that the multicarrier modulation reduces the complexity of the canceller and still provides sufficient coding gain in order to cancel the multiuser interference. The canceller with decoding in the initial decision and multicarrier modulation improves capacity by a factor of 1.4 as compared with the canceller without decoding.