A deterministic multiuser code-timing estimator for long-code bandlimited CDMA systems

In this paper, we present a deterministic multiuser code-timing estimator for asynchronous direct-sequence (DS) code-division multiple-access (CDMA) systems with aperiodic long spreading codes and bandlimited chip waveforms. A key feature of the proposed estimator is that it captures and capitalizes a deterministic structure of the overall interference, namely multi-access interference (MAT) and inter-symbol interference (ISI), in the frequency domain. This allows complete interference elimination in a deterministic manner, which is in general more effective and data-efficient than stochastic approaches. Numerical results show that the proposed estimator can achieve fast acquisition; it is also near-far resistant, providing accurate code acquisition for even overloaded systems (i.e., systems with more users than the processing gain) in multipath fading environments.