Pilot-aided adaptive chip equalizer receiver for interference suppression in DS-CDMA forward link

Blind chip-rate multiuser equalisation

“…Specifically, we consider a DS-CDMA downlink system in will lead to multiple access interference. Hence, much research concentrated on symbol-rate equalisers, such as in [1,2,3]. The ability to apply computationally complex signal processing tasks at higher sampling rates has recently lead to attractive solutions, whereby the equaliser is operated at the chip-rate [4].…”

Receivers with chip-level decision feedback equalizer for CDMA downlink channels

“…Note that the chip-level MMSE LE in [14] is different from that in [11], although the LE in both cases operates at the chip-level. In [11], a chip-level MSE cost function has been used, while a symbol-level MSE cost function was used in [14]. Although the chip-level MSE cost function is conceptually convenient to derive a closed-form solution of the chip-level MMSE LE, it would not be directly used for adaptive implementation due to the updating at the chip rate.…”

“…A despreader can mitigate the MAI after chip-level equalization to restore the orthogonality. As shown in [14], this receiver (with a chip-level equalizer) can be easily implemented with adaptive algorithms.…”

“…Hence, the MAI cannot be completely suppressed by the correlator (or despreader). To avoid this, multiple receiving antennas or a higher sampling rate can be used [11], [14] for the chip-level minimum mean-square error (MMSE) LE. Note that the chip-level MMSE LE in [14] is different from that in [11], although the LE in both cases operates at the chip-level.…”

“…To avoid this, multiple receiving antennas or a higher sampling rate can be used [11], [14] for the chip-level minimum mean-square error (MMSE) LE. Note that the chip-level MMSE LE in [14] is different from that in [11], although the LE in both cases operates at the chip-level. In [11], a chip-level MSE cost function has been used, while a symbol-level MSE cost function was used in [14].…”