Awgn

We develop a canonical, adaptive cascade-structure IIR notch filter to detect and track multiple time-varying frequencies in additive white Gaussian noise. The algorithm uses allpass frequency transformation filters and a truncated gradient. Simulations indicate that our algorithm is computationally simple, converges rapidly, and has good frequency resolution

Very recently the same authors of this paper proposed an encoded pilot system where pilot bits are encoded with the message bits using a systematic code, e.g., a systematic low density parity check (LDPC) code. The authors claimed that the encoded pilot system can have significantly lower complexity and better energy efficiency at the same bandwidth efficiency or even higher bandwidth efficiency over the no pilot systems or the conventional time multiplexed pilot systems. The pilot bits have not been encoded with message bits but multiplexed after the encoder and de-multiplexed before decoding at the conventional receiver. The last case is called a deleted case because its corresponding parity check matrix is obtained by deleting the corresponding columns of the original parity check matrix. This paper finds a difficulty to use the well known sum-product LDPC decoding algorithm for the deleted case because hyperbolic tangent function causes overflow and underflow. In this paper the sum-product algorithm is modified. And this paper takes a well known Hamming code of (3,7) parity check matrix H under additive white Gaussian noise environment (AWGN) and demonstrates that the encoded pilot system is superior to the other systems, using the modified algorithm

In OFDM (Orthogonal frequency division multiplexing) systems, channel estimation and channel
equalization play a key role in overcoming distortions caused by phenomena like fading, delay spread and
multipath effect. In this paper, channel estimation and equalization techniques are analyzed to improve the
performance of OFDM system. The channel estimation techniques considered here are estimation using
wiener filter and frequency domain approach. Prior Channel estimation leads to simple equalization. The
channel equalization techniques employed here are based on LMS algorithm and one tap frequency domain
equalization, under different channels; AWGN, Rayleigh and Rician channels. Eye patterns for different
channels are compared in simulation. It is observed from simulation that wiener filter provides better
estimation and OFDM performance is better under AWGN channel than fading channels. SER curves
shows 6dB improvement in AWGN performance than fading channels to achieve 0.1 SER. In addition, MSE
performance shows fast convergence for AWGN channel.

Stabilisability of an open loop unstable plant is studied under the presence of a bandwidth limited additive coloured noise communication channel with constrained signal to noise ratio. The problem is addressed through the use of an LTI filter explicitly modelling the bandwidth limitation, and another LTI filter to model the additive coloured noise. Results in this paper show that a bandwidth limitation increases the minimum value of signal to noise ratio required for stabilisability, in comparison to the infinite bandwidth, white noise case. Examples are used to illustrate the results in the continuous and discrete framework

This paper presents the first field trials carried out in Spain to test HDTV reception using DVB-T and DVB-T2 systems. High definition and standard definition digital television contents and services were multiplexed and broadcasted from a terrestrial transmitter. The aim of these trials was to analyze DVB-T2 technology when this system is configured according to the needs of terrestrial HDTV broadcasting and to compare the results with DVB-T technology in terms of CNR requirements and achieved data rate. Field measurements were carried out in different scenarios and reception conditions. The study presented in this paper is focused on fixed reception, Gaussian channel, because it is the expected reception condition for HDTV.

ABSTRACT The paper presents the design and performance of a baseband modem for wireless LAN systems. The modem fully complies with the IEEE 802.11g standard draft 4.0. It is capable of operating in any of available modes such as ERP-DSSS/CCK, ERP-OFDM, Extended Rate PBCC, and CCK-OFDM. It offers different data rates from 1 Mbps to 54 Mbps and handles DBPSK, DQPSK, QPSK, 8-PSK, BPSK, 16-QAM, and 64-QAM modulation schemes. We show the BER performance of the presented modem as the result of simulation under AWGN and multipath channels.

The aim of the present work is to illustrate how the empirical mode decomposition (EMD) can be associated with demodulation methods to estimate the instantaneous frequency (IF) of multicomponent non stationary signals. The IF estimation of three methods, namely, Hilbert-Huang transform (HHT) [10], EMD-DESA (Discrete Energy Separation Algorithm)also known as Teager-Huang transform (THT) [2] [5], and B-spline version of the

Mobile operators commonly use macro cells with traditional wide beam antennas for wider coverage in the cell, but future capacity demands cannot be achieved by using them only. It is required to achieve maximum practical capacity from macro cells by employing higher order sectorization and by utilizing all possible antenna solutions including smart antennas. This paper presents enhanced tessellation for 6-sector sites and proposes novel layout for 12-sector sites. The main target of this paper is to compare the performance of conventional wide beam antenna, switched beam smart antenna, adaptive beam antenna and different network layouts in terms of offering better received signal quality and user throughput. Splitting macro cell into smaller micro or pico cells can improve the capacity of network, but this paper highlights the importance of higher order sectorization and advance antenna techniques to attain high Signal to Interference plus Noise Ratio (SINR), along with improved network capacity.  Monte Carlo simulations at system level were done for Dual Cell High Speed Downlink Packet Access (DC-HSDPA) technology with multiple (five) users per Transmission Time Interval (TTI) at different Intersite Distance (ISD). The obtained results validate and estimate the gain of using smart antennas and higher order sectorization with proposed network layout.

In radar applications, the received echo signals reach the array elements via a multiplicity of paths despite the fact that there exists only one target. We address the problem of joint direction of arrival and Doppler frequency estimation using a sensor array in partially known additive noise. We consider a specular reflection model with a radar cross section fluctuating from one pulse repetition interval to another. The proposed model allows the estimation of more paths than sensors. Two approximate maximum likelihood algorithms are proposed. The first approach uses a linear expansion of the noise covariance matrix, whereas the second employs a combination of oblique projections and a zero-forcing solution to alleviate the effect of noise. In contrast to other classical methods, the two approaches are more robust to spatially correlated noise, and they employ more compact cost functions that reduce the dimension of the optimization search. Numerical simulations are provided to assess the basic performance of the two approaches, which are compared to the Crame´r-Rao bound.