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Adopting frequency-domain equalization (FDE) in DS-CDMA can partially restore the orthogonality of users and suppress multiple-access interference (MAI). The existing FDEs are designed with the assumption of additive white Gaussian noise. Although the assumption is quite proper for a variety of applications, it has been revealed that many background noises arising in the reality are with non-Gaussian...
Phase noise can severely impair transmission, especially in uplink space division multiple access (SDMA) scenarios. We derive a soft-decision-directed phase noise estimation and compensation algorithm in combination with iterative block decision feedback equalization (IBDFE) for uplink SDMA single carrier systems, such as those proposed in the 3GPP-LTE standard. The algorithm generalizes earlier algorithms...
In addition to some design flexibilities, the low interference property of code division multiple access (CDMA) makes multi-carrier direct sequence CDMA (MC-DS-CDMA) suitable for possible unlicensed transmissions in the licensed bands. Introducing the concept of time division multiple access (TDMA) into MC- DS-CDMA may further create a new dimension dealing with the interference problem. In this paper,...
Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion and frequency-domain inter-chip interference (ICI) cancellation can be incorporated into turbo decoding (this is called the MMSE turbo equalization in this paper) to improve the bit error rate (BER) performance for direct sequence code division multiple access (DS-CDMA). DS-CDMA MMSE turbo equalization requires...
The bit error (BER) performance of CDMA in a frequency-selective fading channel can be significantly improved by the use of frequency-domain equalization (FDE). There are three methods can be used to implement FDE in CDMA uplink [I. Martoyo et al., 2003]: the cyclic prefix [K.L. Baum et al., 2002], the zero padding and the overlap-cut (OC). However, the first two methods not only yield lower bandwidth...
A CDMA scheme employing block processing (BS-CDMA) had been proposed earlier as an effective multiple access scheme that is robust against multiuser interference (MUI) during uplink transmission where conventional CDMA schemes fail due to orthogonality destruction. However, residual MUI arises in BS-CDMA and its degradation impact becomes severe when high mobility users are present. Two interference...
In this paper, we propose a robust STBC transmission scheme to combat the timing synchronization errors over frequency-selective multiple-access channels. First, the equivalent channel model in the presence of timing synchronization errors is derived and we find that the synchronization errors result in an equivalent channel model with larger number of correlated channel taps. Based on this correlated...
Orthogonality restoring combining (ORC) is appealing for the downlink of multicarrier code-division multiple- access (MC-CDMA) since it can eliminate multiple access interference (MAI) which would otherwise fundamentally limit the CDMA system performance. The ORC output instantaneous signal-to-noise ratio (SNR), however, takes the form of a harmonic mean of SNRs on different subcarriers, making its...
In this paper we present a new method of compensating for complex multipath channel fading in blind multiuser detection for DS-CDMA communication. This compensation allows for the use of different chip pulse shapes. The compensation is based on the incorporation of priors derived from the FFT of the pulse shape. The system employs detectors that incorporate methods of independent component analysis...
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