Data networks (2nd ed.)
Elements of information theory
Elements of information theory
Multiuser Detection
Nonlinear and Optimal Control Systems
Nonlinear and Optimal Control Systems
Adaptive Modulation over Nakagami Fading Channels
Wireless Personal Communications: An International Journal
Adaptive multirate CDMA for uplink throughput maximization
IEEE Transactions on Wireless Communications
Capacity of fading channels with channel side information
IEEE Transactions on Information Theory
A scheme for throughput maximization in a dual-class CDMA system
IEEE Journal on Selected Areas in Communications
Analysis of an up/down power control algorithm for the CDMA reverse link under fading
IEEE Journal on Selected Areas in Communications
IEEE Journal on Selected Areas in Communications
New-User Detection in Time Hopping Multi-User Environment for UWB Impulse Radio Systems
Wireless Personal Communications: An International Journal
Wireless Personal Communications: An International Journal
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We propose a technique for enhancing the achievable spectral efficiency of multiuser direct-sequence code-division multiple-access (DS-CDMA) fading channels in the presence of additive white Gaussian noise (AWGN) and multiple access interference (MAI). The proposed scheme involves the joint optimization of outer loop power control (OLPC) and rate control using variable spreading factors (VSFs). The optimality is in the sense of average spectral efficiency maximization. The optimum outer loop target signal-to-noise ratio (SNR-target) and the corresponding spreading factor are derived jointly, in terms of the number of active users. Along with transmit power adaptation in the inner loop, this leads to maximized average spectral efficiency. Total and truncated channel inversion strategies are used in the inner loop. The average spectral efficiency of the joint optimization scheme is derived for the conventional matched-filter and the multiuser decorrelating detectors. Average transmit power and instantaneous bit error rate (BER) constraints are considered and the performance is evaluated over Nakagami-m flat-fading channels. In low SNRs, the proposed scheme can provide a considerable gain in bits/s/Hz for either of the detectors, compared to a VSF-assisted system that does not exploit OLPC and thus the optimum SNR-target.