Abstract: Wireless ad hoc nodes are freely and dynamically
self-organize in communicating with others. Each node can act as
host or router. However it actually depends on the capability of
nodes in terms of its current power level, signal strength, number
of hops, routing protocol, interference and others. In this research,
a study was conducted to observe the effect of hops count over
different network topologies that contribute to TCP Congestion
Control performance degradation. To achieve this objective, a
simulation using NS-2 with different topologies have been
evaluated. The comparative analysis has been discussed based on
standard observation metrics: throughput, delay and packet loss
ratio. As a result, there is a relationship between types of topology
and hops counts towards the performance of ad hoc network. In
future, the extension study will be carried out to investigate the
effect of different error rate and background traffic over same
topologies.
Abstract: MBMS is a unidirectional point-to-multipoint bearer
service in which data are transmitted from a single source entity to
multiple recipients. For a mobile to support the MBMS, MBMS client
functions as well as MBMS radio protocols should be designed and
implemented. In this paper, we analyze the MBMS client functions
and describe the implementation of them in our mobile test-bed. User
operations and signaling flows between protocol entities to control the
MBMS functions are designed in detail. Service announcement
utilizing the file download MBMS service and four MBMS user
services are demonstrated in the test-bed to verify the MBMS client
functions.
Abstract: Cooperative communication scheme can be substituted
for multiple-input multiple-output (MIMO) technique when it may
not be able to support multiple antennas due to size, cost or
hardware limitations. In other words, cooperative communication
scheme is an efficient method to achieve spatial diversity without
multiple antennas. For satisfaction of rising QoS, we propose a
reliable cooperative communication scheme with M-QAM based Dual
Carrier Modulation (M-DCM), which can increase diversity gain.
Although our proposed scheme is very simple method, it gives us
frequency and spatial diversity. Simulation result shows our proposed
scheme obtains diversity gain more than the conventional cooperative
communication scheme.
Abstract: The development of the signal compression
algorithms is having compressive progress. These algorithms are
continuously improved by new tools and aim to reduce, an average,
the number of bits necessary to the signal representation by means of
minimizing the reconstruction error. The following article proposes
the compression of Arabic speech signal by a hybrid method
combining the wavelet transform and the linear prediction. The
adopted approach rests, on one hand, on the original signal
decomposition by ways of analysis filters, which is followed by the
compression stage, and on the other hand, on the application of the
order 5, as well as, the compression signal coefficients. The aim of
this approach is the estimation of the predicted error, which will be
coded and transmitted. The decoding operation is then used to
reconstitute the original signal. Thus, the adequate choice of the
bench of filters is useful to the transform in necessary to increase the
compression rate and induce an impercevable distortion from an
auditive point of view.
Abstract: In this paper, the signal transmission analysis of the
semicircle-shaped via structure for the differential pairs is presented in
the frequency range up to 10 GHz. In order to improve the signal
transmission properties in the differential pairs, single via is separated
centrally into two semicircle-shaped sections, which are
interconnected with the traces of differential pairs respectively. This
via structure make possible to route differential pairs using only one
via. In addition, it can improve impedance discontinuity around its
region and then enhance the signal transmission properties in the
differential pairs. The electrical analysis such as S-parameter
calculation and eye diagram simulation has been performed to
investigate the improvement of the signal transmission property in the
differential pairs with new via structure.
Abstract: Bluetooth is a personal wireless communication
technology and is being applied in many scenarios. It is an emerging
standard for short range, low cost, low power wireless access
technology. Current existing MAC (Medium Access Control)
scheduling schemes only provide best-effort service for all masterslave
connections. It is very challenging to provide QoS (Quality of
Service) support for different connections due to the feature of
Master Driven TDD (Time Division Duplex). However, there is no
solution available to support both delay and bandwidth guarantees
required by real time applications. This paper addresses the issue of
how to enhance QoS support in a Bluetooth piconet. The Bluetooth
specification proposes a Round Robin scheduler as possible solution
for scheduling the transmissions in a Bluetooth Piconet. We propose
an algorithm which will reduce the bandwidth waste and enhance the
efficiency of network. We define token counters to estimate traffic of
real-time slaves. To increase bandwidth utilization, a back-off
mechanism is then presented for best-effort slaves to decrease the
frequency of polling idle slaves. Simulation results demonstrate that
our scheme achieves better performance over the Round Robin
scheduling.
Abstract: A fully on-chip low drop-out (LDO) voltage regulator with 100pF output load capacitor is presented. A novel frequency compensation scheme using current buffer is adopted to realize single dominant pole within the unit gain frequency of the regulation loop, the phase margin (PM) is at least 50 degree under the full range of the load current, and the power supply rejection (PSR) character is improved compared with conventional Miller compensation. Besides, the differentiator provides a high speed path during the load current transient. Implemented in 0.18μm CMOS technology, the LDO voltage regulator provides 100mA load current with a stable 1.8V output voltage consuming 80μA quiescent current.
Abstract: This paper deals with the localization of the wideband sources. We develop a new approach for estimating the wide band sources parameters. This method is based on the high order statistics of the recorded data in order to eliminate the Gaussian components from the signals received on the various hydrophones.In fact the noise of sea bottom is regarded as being Gaussian. Thanks to the coherent signal subspace algorithm based on the cumulant matrix of the received data instead of the cross-spectral matrix the wideband correlated sources are perfectly located in the very noisy environment. We demonstrate the performance of the proposed algorithm on the real data recorded during an underwater acoustics experiments.
Abstract: Several models have been introduced so far for single
electron box, SEB, which all of them were restricted to DC response
and or low temperature limit. In this paper we introduce a new time
dependent, high temperature analytical model for SEB for the first
time. DC behavior of the introduced model will be verified against
SIMON software and its time behavior will be verified against a
newly published paper regarding step response of SEB.
Abstract: The paper discusses a computationally efficient
method for the design of prototype filters required for the
implementation of an M-band cosine modulated filter bank. The
prototype filter is formulated as an optimum interpolated FIR filter.
The optimum interpolation factor requiring minimum number of
multipliers is used. The model filter as well as the image suppressor
will be designed using the Kaiser window. The method will seek to
optimize a single parameter namely cutoff frequency to minimize the
distortion in the overlapping passband.
Abstract: A filter is used to remove undesirable frequency information from a dynamic signal. This paper shows that the Znotch filter filtering technique can be applied to remove the noise nuisance from a machining signal. In machining, the noise components were identified from the sound produced by the operation of machine components itself such as hydraulic system, motor, machine environment and etc. By correlating the noise components with the measured machining signal, the interested components of the measured machining signal which was less interfered by the noise, can be extracted. Thus, the filtered signal is more reliable to be analysed in terms of noise content compared to the unfiltered signal. Significantly, the I-kaz method i.e. comprises of three dimensional graphical representation and I-kaz coefficient, Z∞ could differentiate between the filtered and the unfiltered signal. The bigger space of scattering and the higher value of Z∞ demonstrated that the signal was highly interrupted by noise. This method can be utilised as a proactive tool in evaluating the noise content in a signal. The evaluation of noise content is very important as well as the elimination especially for machining operation fault diagnosis purpose. The Z-notch filtering technique was reliable in extracting noise component from the measured machining signal with high efficiency. Even though the measured signal was exposed to high noise disruption, the signal generated from the interaction between cutting tool and work piece still can be acquired. Therefore, the interruption of noise that could change the original signal feature and consequently can deteriorate the useful sensory information can be eliminated.
Abstract: IP multicasting is a key technology for many existing and emerging applications on the Internet. Furthermore, with increasing popularity of wireless devices and mobile equipment, it is necessary to determine the best way to provide this service in a wireless environment. IETF Mobile IP, that provides mobility for hosts in IP networks, proposes two approaches for mobile multicasting, namely, remote subscription (MIP-RS) and bi-directional tunneling (MIP-BT). In MIP-RS, a mobile host re-subscribes to the multicast groups each time it moves to a new foreign network. MIP-RS suffers from serious packet losses while mobile host handoff occurs. In MIP-BT, mobile hosts send and receive multicast packets by way of their home agents (HAs), using Mobile IP tunnels. Therefore, it suffers from inefficient routing and wastage of system resources. In this paper, we propose a protocol called Mobile Multicast support using Old Foreign Agent (MMOFA) for Mobile Hosts. MMOFA is derived from MIP-RS and with the assistance of Mobile host's Old foreign agent, routes the missing datagrams due to handoff in adjacent network via tunneling. Also, we studied the performance of the proposed protocol by simulation under ns-2.27. The results demonstrate that MMOFA has optimal routing efficiency and low delivery cost, as compared to other approaches.
Abstract: Independent component analysis (ICA) in the
frequency domain is used for solving the problem of blind source
separation (BSS). However, this method has some problems. For
example, a general ICA algorithm cannot determine the permutation
of signals which is important in the frequency domain ICA. In this
paper, we propose an approach to the solution for a permutation
problem. The idea is to effectively combine two conventional
approaches. This approach improves the signal separation
performance by exploiting features of the conventional approaches.
We show the simulation results using artificial data.
Abstract: This paper reports a distributed mutual exclusion
algorithm for mobile Ad-hoc networks. The network is clustered
hierarchically. The proposed algorithm considers the clustered
network as a logical tree and develops a token passing scheme
to get the mutual exclusion. The performance analysis and
simulation results show that its message requirement is optimal,
and thus the algorithm is energy efficient.
Abstract: This paper presents the theoretical investigation of a
slotted patch antenna. The main objective of proposed work is to
obtain a large bandwidth antenna with reduced size. The antenna has
a compact size of 21.1mm x 20.25mm x 8.5mm. Two designs with
minor variation are studied which provide wide impedance
bandwidths of 24.056% and 25.63% respectively with the use of
parasitic elements when excited by a probe feed. The advantages of
this configuration are its compact size and the wide range of
frequencies covered. A parametric study is also conducted to
investigate the characteristics of the antenna under different
conditions. The measured return loss and radiation pattern indicate
the suitability of this design for WLAN applications, namely, Wi-
Max, 802.11a/b/g and ISM bands.
Abstract: In this paper we present a novel method, which
reduces the computational complexity of abrupt cut detection. We
have proposed fast algorithm, where the similarity of frames within
defined step is evaluated instead of comparing successive frames.
Based on the results of simulation on large video collection, the
proposed fast algorithm is able to achieve 80% reduction of needed
frames comparisons compared to actually used methods without the
shot cut detection accuracy degradation.
Abstract: Optical burst switching(OBS) is considered as one of
preferable network technologies for the next generation Internet. The
Internet has two traffic classes, i.e. real-time bursts and reliable bursts.
It is an important subject for OBS to achieve cooperated operation of
real-time bursts and reliable bursts. In this paper, we proposes a new
effective traffic control method named Separate TB+LB (Token
Bucket + Leaky Bucket : TB+LB) method. The proposed method
presents a new Token Bucket scheme for real-time bursts called as
RBO-TB (Real-time Bursts Oriented Token Bucket). The method also
applies the LB method to reliable bursts for obtaining better
performance. This paper verifies the effectiveness of the Separate
TB+LB method through the performance evaluation.
Abstract: This paper proposes the authentication method using
ESA algorithm instead of using CAVE algorithm in the CDMA
mobile communication systems including IS-95 and CDMA2000 1x.
And, we analyze to apply ESA mechanism on behalf of CAVE
mechanism without the change of message format and air interface in
the existing CDMA systems. If ESA algorithm can be used as the
substitution of CAVE algorithm, security strength of authentication
algorithm is intensified without protocol change. An algorithm
replacement proposed in this paper is not to change an authentication
mechanism, but to configure input of ESA algorithm and to produce
output. Therefore, our proposal can be the compatible to the existing
systems.
Abstract: In order to protect original data, watermarking is first consideration direction for digital information copyright. In addition, to achieve high quality image, the algorithm maybe can not run on embedded system because the computation is very complexity. However, almost nowadays algorithms need to build on consumer production because integrator circuit has a huge progress and cheap price. In this paper, we propose a novel algorithm which efficient inserts watermarking on digital image and very easy to implement on digital signal processor. In further, we select a general and cheap digital signal processor which is made by analog device company to fit consumer application. The experimental results show that the image quality by watermarking insertion can achieve 46 dB can be accepted in human vision and can real-time execute on digital signal processor.
Abstract: Orthogonal frequency division multiplexing (OFDM)
has developed into a popular scheme for wideband digital
communications used in consumer applications such as digital broadcasting, wireless networking and broadband internet access. In
the OFDM system, carrier frequency offset (CFO) causes intercarrier
interference (ICI) which significantly degrades the system error performance. In this paper we provide an exact evaluation method for error performance analysis of arbitrary 2-D modulation OFDM systems with CFO, and analyze the effect of CFO on error performance.