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Several attractive features of ultra wideband (UWB) communications make it a good candidate for physical-layer of wireless sensor networks (WSN). These features include low power consumption, low complexity and low cost of implementation. In this paper, we present an opportunistic power assignment strategy for distributed detection in parallel fusion WSNs, considering a Nakagami-m fading model for...
A novel low-power switched-capacitor integrator based on dynamic-source-follower amplifiers is proposed and applied to a 2nd-order ΔΣ modulator. Circuit simulation assuming 0.18-μm CMOS technology shows that the present integrator can drastically reduce the power dissipation compared with conventional op-amp-based integrators. A figure-of-merit (FOM) of 0.172 pJ/conv·step has been predicted with a...
In our previous study, we proposed a single-carrier frequency domain adaptive antenna array (SC-FDAAA) for the conventional cellular network. It has been proved that the SC-FDAAA can effectively suppress the interfering signals from other users in a severely frequency selective fading channel. In this paper, we study the SC-FDAAA for distributed antenna network (DAN) and two DAN SC-FDAAA schemes are...
Recently, a frequency-domain block signal detection (FDBD) using maximum likelihood detection (MLD) employing QR decomposition and M-algorithm (QRM-MLD) was proposed for the reception of the single-carrier (SC) signals transmitted over a frequency-selective fading channel. SC-FDBD with QRM-MLD can significantly improve the bit error rate (BER) performance of SC transmission while reducing significantly...
Broadcast nature of the wireless channel enables wireless communications to make use of network coding at the physical layer (PNC) to improve the network capacity. Recently, narrowband and later broadband wireless analog network coding (ANC) were introduced as a simpler implementation of PNC. The coherent detection and self-information removal in ANC require accurate channel state information (CSI)...
Distributed antenna system (DAS) or distributed multiple-input multiple-output (MIMO) can enhance the cellular throughput performance, thanks to the largely separated multiple remote antenna units (RAU) which can experience the different large scale fading and the small scale fading. So far, much research work has been published in the DAS. However, to the authors' best knowledge, there is no research...
Frequency-domain filtered single carrier (SC)-FDMA signal has properties of reduced peak-to-average power ratio (PAPR) and increased frequency diversity gain. However, if the carrier-frequency separation is kept the same as in the case of the transmit filter roll-off factor α=0, the adjacent users' signal spectra overlap and the multi-user interference (MUI) is produced. In our previous work, we proposed...
Power efficiency is a key issue in wireless sensor networks due to limited power supply. Buffer management is also crucially important in the scenario where the incoming traffic is higher than the output link capacity of the network since a buffer overflow causes power waste and information loss if a packet is dropped. There are many available buffer management schemes for traditional wireless networks...
In the single-carrier (SC) transmission, minimum mean square error frequency-domain equalization (MMSE-FDE) can achieve a good bit error rate (BER) performance in a frequency-selective fading channel. The conventional FDE requires the insertion of cyclic prefix (CP) to make the received signal block to be a circular convolution of the transmit signal and the channel. Overlap FDE requires no CP insertion...
Orthogonal frequency division multiplexing (OFDM) system with frequency domain equalization (FDE) requires reliable channel estimation (CE). OFDM has a problem of high peak-to-average power ratio (PAPR), which makes it very sensitive to nonlinear distortions, affecting the channel estimation accuracy. In this paper, we investigate the effect of the nonlinearity to the the OFDM system with pilot-assisted...
Distributed antenna network (DAN) is a promising wireless network to solve the problems arising from shadowing and path lesses as well as frequency-selective fading. Many antennas are spatially distributed around each base station (BS) so that with a high probability, some antennas can always be visible from a mobile station (MS). Recently, we proposed a 2-dimensional water-filling (2D-WF) transmit...
Single-carrier distributed antenna network (SC-DAN), in which a group of multiple antennas are distributed in a cell serve a user, can mitigate adverse impacts of path loss, shadowing loss and multipath fading. Frequency-domain space-time block coded-joint transmit/ receive diversity (FD-STBC-JTRD) is attractive for downlink transmission since an arbitrary number of distributed transmit antennas can...
Recently, we proposed a joint iterative transmit/receive (Tx/Rx) minimum mean square error (MMSE) frequency-domain equalization (FDE) & inter-symbol interference (ISI) cancellation (ISIC) for single-carrier (SC) block transmissions. In this paper, we extend the previously proposed joint iterative Tx/Rx MMSE-FDE & ISIC to the SC hybrid automatic repeat request (HARQ) packet access to exploit...
In this paper, we propose a spectrum division & adaptive subcarrier allocation for cooperative amplify-and-forward (AF) relay using single carrier-frequency division multiple access (SC-FDMA). To obtain increased frequency diversity gain, the transmit SC signal spectrum is divided into sub-blocks, to each of which a different set of subcarriers (resource block) is adaptively allocated based on...
The peak-to-average power ratio (PAPR) of Nyquist filtered broadband single carrier (SC)-FDMA signals can be reduced by increasing the filter roll-off factor α. Furthermore, an additional frequency diversity gain can be obtained by making use of the excess bandwidth introduced by the transmit filtering. However, if the carrier-frequency separation is kept the same as in the case of α=0, the adjacent...
In this paper, we demonstrate through graphical means the coherent demodulation of Gaussian Minimum-Shift-Keying (GMSK) that is made possible because the pulses after the Gaussian lowpass filter retain the unit area such that the phase deviation has the π/2 value. Although it is straightforward to show analytically that the MSK waveform can be split into two antipodal pulse streams modulating an in-phase...
In the future wireless communication systems, the broadband wireless technology which enables Giga-bps class data services is demanded. Broadband wireless channels become extremely frequency-selective and cause severe inter-symbol interference (ISI). Furthermore, the average received signal power changes in a random manner because of the shadowing and path losses according to the movement of a mobile...
The uplink capacity evaluation of cellular multiple input multiple output (MIMO) system is of great interest but not straight forward. This paper presents a framework to evaluate the uplink cellular capacity. In this framework, the effects of co-channel interference (CCI) as well as the effects of transmit power control (TPC) have been taken into consideration. The uplink capacities assuming various...
Broadband wireless channel comprises many propagation paths having different delay times. This results in a severe frequency-selective fading channel. Frequency-domain equalization reception based on the minimum mean square error criterion (called receive MMSE-FDE in this paper) can exploit the channel frequency-selectivity to improve the bit error rate (BER) performance of broadband single-carrier...
Broadband wireless technology which allows higher-than-1Gbps data transmission with extremely low transmit power may be necessary in future wireless communication systems. The wireless channel for such broadband transmissions is severely frequency-selective. Frequency-domain wireless signal processing may play an important role in achieving a good signal transmission performance. The multi-carrier...
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