Recent progress in establishing the capability of radios to operate in full duplex mode on a single channel has been attracting growing attention from many researchers. We extend this work by considering the application to small cells, in particular resource-managed cellular systems similar to the TDD variant of LTE. We derive conditions where full duplex operation provides improved throughput compared to half duplex for a single cell scenario. We present a hybrid scheduler that defaults to half duplex operation but can assign full duplex timeslots when it is advantageous to do so. We compare the performance of such a scheduler with a traditional half duplex scheduler in terms of throughput and energy efficiency. Our simulation results show that we achieve as much as 81% of the capacity doubling promised by full duplex, with limitations deriving from interference effects specific to full duplex operation.

The HSDPA mode of the 3GPP UMTS FDD standard extends the peak downlink rate of the W-CDMA waveform to 14 Mbps. To achieve high rates across a multipath channel the demodulator must include an advanced receiver rather than a conventional Rake. This paper presents the performance of an NLMS-based adaptive equalizer that supports mobile velocities as high as 250 km/h. The equalizer works with radio and implementation impairments typical of a non-HSDPA receiver, so redesign of the terminal front end is not required. A key aspect of the design is dynamically adjusting the equalizer step size and leakage parameter. There is often concern about the ability of an adaptive algorithm to operate in a highly mobile environment. The transient behavior is discussed in the context of HSDPA operation and examples are provided of initial convergence and operation after a sudden change in propagation conditions.

Signal-to-noise ratio (SNR) is an important parameter in many receivers. In a previous letter B Li et al., (2002) we derived a maximum-likelihood amplitude estimator and obtained a low bias SNR estimation algorithm for a binary phase-shift keying (BPSK) modulated signal. We now extend the result and obtain a low bias SNR estimator for multiple phase-shift keying (MPSK) modulation. We compare our algorithm with others, such as a decision-directed approach. Simulations show that the new algorithm provides not only much lower bias and but also much smaller mean square error (MSE).

An approximation is presented for the loss in performance when the Viterbi algorithm receiver for CPM (continuous phase modulation) signals is subject to a phase offset. Pairs of symmetric error events are used to derive a closed-form result that approaches the asymptotic expression, based solely on minimum distance, as E/sub s//N/sub 0/ approaches infinity. The improved accuracy of the approximation is demonstrated by comparison with a Monte Carlo simulation.>

In this work a new version of the cross-coupled phaselocked loop (CCPLL) interference canceller is presented. This detector consists of two phase-locked loop (PLL) demodulators interconnected in such a manner as to permit one PLL to lock onto and track the instantaneous frequency of the stronger received signal, while the other loop tracks and demodulates the weaker of two received signals. In addition, the receiver includes control loops to estimate the instantaneous amplitude of both received signals. This demodulator, therefore, has the capability of detecting both the desired and interfering signals, even though the interferer may be stronger than the desired signal and may share the same frequency band. The defining nonlinear differential equations for the CCPLL structure are derived and transient acquisition responses are obtained using computer-aided analysis. The CCPLL has numerous technological applications in suppressing a wide variety of cochannel and adjacent channel interferers.