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This paper presents a power-saving communication system for the link from an in-body sensor to an on-body sensor over the abdominal channel in medical wireless body area networks. The idea of the work is to exploit the time diversity of the channel coding and the high dimensional signal constellation of M-ary pulse position modulation (M-PPM) to improve the system performance. In addition to the illustration...
In this paper, an energy efficient adaptive modulation scheme is proposed for a wireless cognitive radio ad hoc network, where each node is equipped with cognitive radio and the network is an OFDMA system operating on time slots. In each slot, the users with new traffic demand will sense the spectrum and locate the available subcarrier set. Then they choose subcarriers with favorable channel condition...
Spectrum sensing in the context of wireless microphone (WM) signals is considered in this paper. The spectrum sensing algorithm developed in this study makes use of the property that the bandwidth of the WM signal is narrow compared with the bandwidth of a digital television (DTV) channel. As a result, the power of the WM signal is highly concentrated in the frequency domain and there are apparent...
By exploiting properties of the wireless medium, network coding may provide even larger throughput increases for wireless networks than possible for wired networks. In particular, simultaneously transmitted signals are seen as noisy linear combinations at the antennas of receivers. It is thus quite tempting to use the physical layer to directly perform network coding "on the air". However,...
In this paper, we develop an approach toward joint source-channel coding (JSCC) for JPEG compressed image transmission. First, a data partition (DP) technique is employed to divide the JPEG bitstream into three groups, namely, Huffman codes, DC coefficients and AC coefficients. Second, we combine the rate-compatible punctured convolutional (RCPC) codes to protect the coded data according to channel...
Three applications in wireless networks where model-free stochastic learning is applicable, are discussed. The learning based optimization problems are formulated and simulation results are presented. Some open issues are also discussed.
In this paper, we propose a cross-layer optimization approach that exploits retransmission diversity in wireless CDMA communications. Conventionally, data packets that are not correctly detected are usually dropped. These dropped packets can be used to help data packet detection. By exploiting all the retransmitted packets, data packets can be correctly detected with higher probability. The proposed...
This paper addresses adaptive channel estimation for time-varying mobile wireless channels with nonstationary statistics. We presents a reduced complexity adaptive channel estimator based on a set membership filtering approach known as the Optimal Bounding Ellipsoid (OBE) algorithm. To exploit time and frequency domain correlation properties of the channel in an efficient low-complexity way, we allow...
Ultra-wideband (UWB) systems possess several distinct features such as very high data rate, large multipath or frequency diversity and improved ranging precision while requiring low-power low-complexity transceivers. Among the different modulation schemes, differential PSK is an attractive option because it does not require channel estimation, and hence reduces implementation complexity. This paper...
This paper discusses the performance of the wavelet based filtered multi-tone (WFMT) modulation. The novel WFMT modulation was proposed in 2003 for improving characteristics of wireless and DSL multicarrier systems. In this paper we describe a main idea of WFMT and discuss the advantages of this novel modulation. The WFMT modulation in comparison with OFDM and DMT has low level of out-of-band side...
In this paper we investigate bounds on performance of joint parameter estimation and modulation classification. The Cramer-Rao Lower Bounds (CRLBs) of non-data aided joint estimates of signal amplitude and phase, and noise power are derived for binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK) signals. In addition, an upper bound on performance of Quasi Hybrid Likelihood Ratio...
In this paper, we propose a cognitive radio-based multi-user resource allocation framework for mobile ad hoc networks using multi-carrier DS CDMA modulation over a frequency-selective fading channel. In particular, given pre-existing communications in the spectrum where the system is operating, in addition to potential narrow-band interference, a channel sensing and estimation mechanism is provided...
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