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Título:
Performance bounds for group decoding over asynchronous Gaussian multiple-access channels
Autor/es:
GRACIELA CORRAL BRIONES; MARIO R. HUEDA
Lugar:
Digital Commun. Res. Lab., Univ. Nacional de Cordoba, Argentina
Reunión:
Conferencia; GLOBECOM '03. IEEE Global Telecommunications Conference, 2003.; 2003
Resumen:
Group decoding receivers (GDRs) are an attractive way to improve the
performance of multiuser systems with highly correlated users. These
reduced complexity receivers use jointly the coding information of a
subset of users and multiuser information. Performance of GDR for
synchronous multiple-access channels is upper bounded by E.A. Fain and
M. Varanasi (see IEEE Trans. on Commun., vol.49, no.6, p.1021-32,
2001). However, upper bounds of GDR for asynchronous multiple-access
channels (where the effect of error propagation is critical), have not
been reported so far. We derive an upper bound for the performance of
GDR for asynchronous multiple-access channels considering error
propagation effects. We show that performance analysis based
exclusively on minimum distance error events is poor, even at high
signal-to-noise ratios (SNRs). To improve the accuracy of analytical
estimates, new bounds accounting for the contribution of non-minimum
distance error events and error propagation are derived. Comparisons
with values obtained from computer simulations show the excellent
accuracy of the proposed bounds. Our results also reveal that
performance of GDR in channels with highly correlated users is severely
affected by error propagation. To mitigate this problem, we propose a
new scheme based on the combination of the generalized Viterbi
algorithm and the GDR. We show that the proposed receiver is able
nearly to eliminate error propagation with low additional complexity.