This paper analyzes first-order full-digital coherent and noncoherent PN code tracking loops for bandlimited baseband direct-sequence spread-spectrum signals under AWGN. The considered loop structures which employ a decimator to control the PN code phase have implementation advantages over loops employing higher-order interpolators. Analytic expressions are derived for the steady-state timing mean squared error, mean pull-in time, mean time to lose lock and the steady-state uncoded and coded bit error rates by employing appropriate Markov chain models. The analytical results are verified to be very accurate via computer simulations. Results are presented for BPSK spreading but extension to QPSK spreading is straightforward.

In this paper, efficient symbol timing synchronization algorithms for IEEE 802.11a/g wireless LAN systems in multipath channels are proposed. For improved accuracy, the algorithms utilize an effectively elongated training symbol together with nonlinear soft-limiting of the correlator output. The algorithms allow efficient utilization of the guard interval in multipath channels. Simulation results show that the proposed algorithms significantly outperform conventional algorithms.

In digital communication systems employing binary phase-shift keying and non-data-aided carrier phase recovery, a 180 carrier phase ambiguity is inevitable. Here, we propose a simple modification to the standard regular repeat-accumulate (RA) code structure by exploiting the differential encoding inherent to the inner encoder of RA codes resulting in codes that are 180 rotationally invariant. The proposed code structure exhibit performance virtually identical to that of standard regular RA codes with zero carrier phase offset under both zero and 180 carrier phase offsets with negligible additional hardware complexity.

A novel modified midtread quantizer is proposed for number-controlled oscillator frequency quantization in digital phase-locked loops (DPLLs). We show that DPLLs employing the proposed quantizer provide significantly improved cycle slip performance compared to those employing conventional midtread or midrise quantizers, especially when the number of quantization bits is small and the magnitude of input signal frequency normalized by the quantization interval is less than 0.5.