Kimmo Kettunen

B2.5 Multiuser receivers and channel coding

Receivers Using Iterative Decoding with Interference Cancellation

A novel receiver structure that utilizes the decoding information for multiuser detection was proposed and analysed in the publication [1,4]. This receiver structure was based on the single-user version of the uncoded maximum a priori criterion. The optimal as well as two suboptimal  multiuser likelihood algorithms were presented. The proposed receiver structure used a soft-input-soft-output (SISO) channel decoder that required the estimation of the channel variance.In [2], the impact of different variance estimation algorithms was studied.

Performance of multistage IC receivers in coded DS-CDMA systems

We derived two lower bounds [3] for the capacity of interference cancellation (IC) CDMA receivers, when channel coding or other means are used to improve the reliability of the tentative decisions. We used these bounds to estimate the capacity of such CDMA recivers when operating over a correlated Rayleigh fading channel. This was done to investigate, whether these kind of receivers can operate without the deep interleaving,which is needed to make the channel coefficients uncorrelated and which causes undesireable long delays in the cancellation.

Publications

[1] K. Kettunen, T. Laakso, "Iterative multiuser receiver utilizing soft decoding information", in Proceedings in Proc. IEEE International Communications Conference, Vancouver, BC, Canada, June 1999 pp. 942-946.

[2] K. Kettunen, "Iterative multiuser receiver/decoders with enhanced variance estimation", in Proc IEEE 49th Vehicular Technology Conference, Houston, TX, USA, May 1999, pp. 2318-2322.

[3] K. Kettunen, "Performance bounds for multistage IC receivers in coded DS-CDMA systems", submitted to IEEE Comm. Letters in November 1999. (Not available in electronic form.)

[4] K. Kettunen, "Iterative multiuser receivers in coded CDMA systems", in Proc. IEEE Finnish Signal Processing Symposium, Oulu, Finland, May 1999, pp. 15-19.

[5] R. Insa Hernandez, R. Baghaie, and K. Kettunen, "Implementation of Gram-Schmidt conjugate direction and conjugate gradient algorithms", in Proc. IEEE Finnish Signal Processing Symposium, Oulu, Finland, May 1999, pp. 165-169.

[6] K. Raatikainen, H. Jormakka, K. Kettunen, J. Sevanto, K. Valtari, "Adapting Mobile Networks into TINA Systems," in Proc. ACTS Mobile Communication Summit '98, Rhodes, Greece, June 8 - 11, 1998, s. 776-781. (Related non-RAVE publication. Not available in electronic form.)