|
Optimization and Performance Enhancement of Multiuser Detection in DS-CDMA System
-- Manoj Dewangan and Ajay Somkuwar
This paper presents the optimization and performance enhancement of multiuser detection in
Direct Sequence Code Division Multiple Access (DS-CDMA) system by using subspace blind linear Minimum Mean Square
Error (MMSE) detector. The proposed scheme uses efficient Bit Error Rate (BER) by use of Gold sequence, the performance
of subspace linear MMSE multiuser detection
algorithms, and yields better performance and lower
computational complexity in contrast to DMI blind linear MMSE detector
algorithms. A simulation example is given to compare
for various codes such as M-sequence, and Gold-sequence.
© 2010 IUP. All Rights Reserved.
Channel Estimation for Multiuser
Mimo-ofdm System
-- K Jayanthi and P Dananjayan
Multi-Input Multi-Output (MIMO) systems with multiple antennas at both the transmitter and receiver are
anticipated to be widely employed in future wireless networks due to their predicted tremendous system capacity.
Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier modulation technique which takes the benefits of
high spectral efficiency, resiliency to RF interference, and lower multi-path distortion. The combination of
MIMO-OFDM is very natural and beneficial since OFDM enables support of more antennas and larger bandwidths.
To protect the transmitted data against random channel impairments, it is desirable to employ Link Adaptation (LA).
To perform LA, the transmitter should know the prevailing channel state information. Generally, the Signal-to-Noise
Ratio (SNR) is used as a Channel Quality Indicator (CQI) but in complex MIMO-OFDM systems, this is not sufficient.
Therefore, more advanced channel quality indicators such as instantaneous SNR, Shannon capacity and Log Likelihood
Ratio (LLR) values are to be considered for efficient link adaptation. The main objective of this paper is to estimate
the channel information using LS and QR Decomposition (QRD) algorithm. And also to enhance the performance of
the multiuser MIMO-OFDM system in terms of quality and capacity using an efficient link adaptation technique
mechanism. The obtained simulation results also prove that the quality of the system is highly enhanced by using channel
estimation algorithms.
© 2010 IUP. All Rights Reserved.
Receiver Position Error Analysis Using Point Solution Approach Algorithm
-- V Venkata Rao, G Sasibhushana Rao and M Madhavi Latha
The Global Positioning System (GPS) has become the main tool in positioning and Earth measurement
applications, and its accuracy relies in the precise knowledge of the satellite orbits and time. Different approaches have
been developed to estimate the receiver position. In this paper a non-recursive point solution approach algorithm is
proposed for the receiver position estimation. The receiver position is estimated without considering the various error
sources namely satellite clock bias, atmospheric delay, error in the broadcast ephemeris data, multipath error and
receiver tracking error. The results are analyzed by computing the mean position
(), standard deviation (s) and variance
(s2) over a period of the day and the results obtained are very promising. The error analysis is carried out by collecting
the several days of dual frequency (1575.42 MHz and 1227.6 MHz) GPS receiver data from the Andhra University
Engineering College, Visakhapatnam (Latitude/Longitude
17.73o/83.32o). The position error analysis studied in this paper will
be helpful to surveyors and GPS Aided GEO Augmented Navigation (GAGAN) users over the Indian subcontinent
in determining the obtained position accuracy over the 24 hour period particularly for aircraft purposes.
© 2010 IUP. All Rights Reserved.
Simulation, Design and Development of Complementary-Symmetry
Microstrip Antenna for Compactness, Enhanced Gain, Bandwidth
and Low Cross-Polarization
-- N M Sameena, G P Maddani, R B Konda,
S K Satnoor and S N Mulgi
This paper presents a novel design of Complementary-Symmetry rectangular Microstrip Antenna (CSMA) with
modified ground plane for compactness, enhanced gain, bandwidth and low cross-polarization operation. A 58%
size compactness is achieved when compared with the conventional rectangular microstrip antenna. The antenna
operates for 18.78% of bandwidth and gives maximum of 8.21 dB gain. The cross-polar power level of _22.9 dB down
is obtained with respect to co-polar. The effect of complementary-symmetry geometry and modified ground plane
for improving the antenna parameters is studied and reported. The experimental results are in agreement with the
simulated results. The proposed antennas may find applications in wireless communication systems.
© 2010 IUP. All Rights Reserved.
A Study on the Performance of Wideband Bandpass Filter Designed
Using Multimode Resonator
with Etched Rectangular Lattice
-- P K Singhal, Suman Mathur and R N
Baral
A compact wideband bandpass filter is proposed and implemented using a Multiple-Mode Resonator (MMR) with
etched rectangular lattice, aiming to obtain a wide-passband
of 0.9 GHz-2.1 GHz. For the microstrip bandpass filter the return
loss is found to be higher than 10 dB. After optimization, a good wideband bandpass behavior with three transmission
poles is realized theoretically and experimentally. The measured results are found to be in good agreement with the
analytical values.
© 2010 IUP. All Rights Reserved.
Fuzzy Set Optimization Technique
for Virtual Topology Reconfiguration for IP-over-WDM Networks with
QoS Parameters
-- Ramasamy Mariappan, T Ravi and R S D Wahida Banu
The paper studies the application of fuzzy set optimization techniques for the reconfiguration of optical internets
using Internet Protocol (IP) over Wavelength Division Multiplexed (WDM) (IP-over-WDM) technology. The IP-over-WDM
networking technology with terabits per second bandwidth become a natural choice for the future generation internet
networks (optical internets), Wide Area Network (WAN) environments and backbone networks due to its potential ability to
meet the rising demand of high bandwidth and low latency communication. Recently, Virtual Topology Reconfiguration
(VTR) of IP-over-WDM networks has received greater attention among researchers. Fuzzy set finds many applications in the
field of network engineering, which includes linear programing, traffic prediction, network modeling, traffic modeling, etc.
In this paper, we have presented a new approach for reconfiguring virtual topology of IP-over-WDM networks using
fuzzy set optimization technique. The computed results show that this new approach achieves better performance in terms
of computational accuracy, number of changes and Average Weighted Hop Count (AWHT).
© 2010 IUP. All Rights Reserved.
|
