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Issue 1, Volume 11,
January 2012
Title
of the Paper:
Cross-layer Packet Dependent OFDM Scheduling
Based on Proportional Fairness
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Authors:
Hua Hou, Gen-Xuan Li
Abstract: This paper assumes each user has more than one queue, derives a new
packet dependent proportional fairness power allocation pattern based on the
sum of weight capacity and the packet’s priority in users’ queues, and
proposes 4 new schemes of cross-layer packet dependent OFDM scheduling for
heterogeneous classes of traffic based on proportional fairness. Scenario 1,
scenario 2 and scenario 3 lead respectively artificial fish swarm algorithm,
self-adaptive particle swarm optimization algorithm and cloud adaptive
particle swarm optimization algorithm into sub-carrier allocation in packet
dependent proportional fairness scheduling, and use respectively new power
allocation pattern, self-adaptive particle swarm optimization algorithm and
population migration algorithm to allocate power. Scenario 4 uses greedy
algorithm concerning fairness to allocate sub-carriers, and uses new power
allocation pattern to allocate power. Simulation indicates scenario 1,
scenario 2 and scenario 3 raise the system’s total rate on the basis of
undertaking the fairness among users’ rates and average packet delay; scenario
4 not only meets the demands of users’ rates and average packet delay, but
also improves the fairness among users’ rates.
Keywords: Multi-user OFDM, Scheduling, Proportional fairness, Swarm intelligence
algorithm, Artificial fish swarm algorithm, Particle swarm algorithm,
Population migration algorithm
Title
of the Paper:
Low-Energy-Transmission of Data on Submicron
Interconnects
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Authors:
A. Mahdoum, L. Hamimed, M. Louzri, M. Saadaoui
Abstract: We present in this paper a CAD tool that aims at designing
low-energy buses. The Graphical User Interface (GUI) we developed manages many
techniques dealing with the addressed problem: simple coding, coding subject
to fixed / dynamic probabilities and an enhanced dynamic probabilities- based
technique. Moreover, this environment allows tuning the parameters of data
encoding / decoding and is able to generate different gains by varying the
size of the bus transferring the encoded data. Finally, this tool can be
easily configured to integrate new coding techniques and use one of them when
favorably compared against the other techniques.
Keywords: Communications Submicron interconnects Energy dissipation Data
transfer
Title
of the Paper:
IPSD: New Coverage Preserving and
Connectivity Maintenance Scheme for Improving Lifetime of Wireless Sensor
Networks
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Authors:
A. Balamurugan, T. Purusothaman
Abstract: In many applications it is necessary to have some guarantees on the
coverage, connectivity and lifetime of the Wireless Sensor Networks(WSN).
Coverage problem is regarding how to ensure that each of the points in the
region to be monitored is covered by the sensors. In maximizing coverage, the
sensors need to be placed not too close to each other so that the sensing
capability of the network is fully utilized and at the same time they must not
be located too far from each other to avoid the formation of coverage holes.
On the other hand from connectivity point of view, the sensors need to be
placed close enough so that they are within each other communication range
thus connectivity is ensured. Once coverage and connectivity are ensured, the
overall lifetime of the network gets increased thereby improving the quality
of service (QoS) of the Wireless Sensor Network (WSN). The concept of Integer
Programmed Sensor Deployment (IPSD) scheme is being proposed, with a set of
relay nodes a triangular lattice is formed by the grid based approach thus
providing maximum coverage and connectivity. Integer Linear Programming (ILP)
is brought into existence for eliminating the unused relay nodes thereby
enhancing the coverage and connectivity with minimum number of relay nodes.
Simulation is performed using NS-2 and the results shows that the proposed
scheme provides better results in large scale WSN with improved coverage and
connectivity.
Keywords: WSN, ILP, relay node, coverage, connectivity
Title
of the Paper:
Video Multicast Over Wireless Ad Hoc
Networks
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Authors:
Osamah S. Badarneh, Michel Kadoch
Abstract: Existing video multicast routing protocols in wireless ad hoc
networks have been developed under the assumption that destination nodes wish
to receive all the information sent by the multicast source, i.e., they do not
support heterogeneous destinations. This paper addresses the problem of video
multicast for heterogeneous destinations in wireless ad hoc networks. Multiple
Description Coding (MDC) is used for video coding. MDC generates multiple
independent bit-streams, where the multiple bit-streams are referred to as
multiple descriptions (MD). Furthermore, MDC enables a useful reproduction of
the video when any description is correctly received. Specifically, we propose
three novel multiple multicast trees routing protocols. The first protocol
constructs multiple disjoint multicast trees and assigns MD video in a
centralized fashion, and is referred to as Centralized MDMTR (Multiple
Disjoint Multicast Trees Routing). The second protocol is a variant of
Centralized MDMTR. We refer to it as Sequential MDMTR. The main difference
between Sequential MDMTR and Centralized MDMTR is that, Sequential MDMTR
sequentially assigns MD video to the destination nodes. In order to reduce
construction delay and routing overhead, we further propose Distributed MDMTR
protocol. Both protocols, Centralized MDMTR and Distributed MDMTR, exploit the
independent-description property of MDC along with multiple disjoint paths to
increase the number of assigned video descriptions to each destination. We
extensively evaluate our proposed protocols by simulations and show that they
outperform the existing work.
Keywords: Video multicast, wireless ad hoc networks, multiple description
coding, heterogeneous destinations
Issue 2, Volume 11,
February 2012
Title
of the Paper:
An Integrated Cross Layer Approach for
Multimedia Streaming using Multipath and Multiple Description Coding in Mobile
Ad-Hoc Networks
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Authors:
N. Gomathi, P. Seethalakshmi, A. Govardhan
Abstract: The objective of this paper is to propose a novel method for
enhancing the QoS of multimedia applications in mobile adhoc networks by using
Multipath and Multi Description Coding. The enhancement is achieved by
implementing the Multi Description Coding (MDC) at application layer along
with Connectionless Light Weight Protocol (UDPLite) in transport layer and
multipath at network layer. This approach achieves an increase of 12.75% in
Peak Signal to Noise Ratio (PSNR) which is an improvement in PSNR as compared
to the conventional methods.
Keywords: MANETS, QoS, Multiple Description Coding (MDC), UDPLite, Multipath
Transport, Video Streaming, PSNR
Title
of the Paper:
Synchronization and Cell Search Algorithms
in 3GPP Long Term Evolution Systems (FDD mode)
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Authors:
Abdo N. Gaber, Loay D. Khalaf, Ahmad M. Mustafa
Abstract: In this paper initial downlink synchronization (sync) and cell
identification algorithms for the 3rd generation partnership project (3GPP)
long term evolution (LTE) systems are presented. The frequency division duplex
(FDD) mode is used in the downlink radio frame structure. A user equipment
digital receiver architecture is proposed. The orthogonality of signals in
orthogonal frequency division multiplexing (OFDM) may be lost due to some
impairments such as frequency, time, and phase offsets. Therefore, major parts
of this research are involved in restoring the orthogonality at the user
equipment (UE) by using some techniques to estimate the sync parameters, and
to detect cell identity among candidate cells based on sync signals. A Farrow
structure interpolator is used to compensate the fractional timing offset.
Both inter site synchronous and inter site asynchronous networks are
presented. Computer simulations are used to demonstrate the performance of the
proposed schemes with multipath Rayleigh fading channel, frequency offsets,
timing offsets, and additive white Gaussian noise (AWGN). Results show high
probability of cell identification in a very short time 20 ms in both multi
cell model scenarios, especially when multiple input multiple output (MIMO)
technique, oversampling at the UE, and high order Farrow structure
interpolator are used.
Keywords: 3GPP LTE, OFDM, MIMO, Frequency and Time Synchronization, Cell Search
Title
of the Paper:
A New Adaptive Model for Throughput
Enhancement and Optimal Relay Selection in IEEE 802.16j Networks
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Authors:
D. Satish Kumar, N. Nagarajan
Abstract: IEEE 802.16 standard is created to compete with cable access
networks. In the beginning end users are immobile and have a line of sight
with base station, now it moved to mobile non line of sight (NLOS) with the
new standard IEEE 802.16e and IEEE 802.16j. The new IEEE 802.16j standard
which is an amendment to IEEE 802.16e is mobile multi hop relay (MMR)
specification for wireless networks. In this paper we have proposed a new
adaptive model for transparent mode IEEE 802.16j MMR networks and studied
about the throughput enhancement, optimal relay placement and spatial reuse
techniques. We have used four mobile stations (T-MS) connected to transparent
mode base station (TMR-BS), which are moving at a speed of 20 m/sec. The T-MS
are initially placed near to TMR-BS and are moving away from TMR-BS. The
average throughput achieved without relay T-RS is 792.045913 Kbps and the
average throughput achieved with relay TRS is 1261.856667 Kbps. There is
37.2318% increase in the throughput by placing transparent mode relays TRS at
suitable position.
Keywords: IEEE 802.16j, relay modes, Optimal relay placement, WIMAX, NCTUns
Title
of the Paper:
Code Scattering and Reduction in OVSF Code
Blocking for 3G and beyond Mobile Communication Systems
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Authors:
Neeru Sharma, Davinder S. Saini
Abstract: Scattered vacant codes in Orthogonal Variable Spreading Factor
(OVSF) code based 3G and beyond WCDMA wireless networks leads to code blocking
which further gives call blocking. The paper proposes four single code
assignment schemes to reduce code scattering. The use of assignment scheme
depends upon the type of input calls. The code reservation assignment (CRA) is
used to efficiently handle one or higher rate class calls. It assigns priority
number to the children of priority class codes such that the future
availability of vacant codes in the priority layer is the highest. The
remaining three code assignment schemes favors low to medium calls. The code
assignment using group leaders uses busy codes (capacity) under predefined
leaders to handle future calls. The code blocking in group leader approach can
be reduced further if the used capacity of all the parents of the eligible
vacant codes is examined and the code whose parent has maximum used capacity
is used for new call. In adjacent vacant codes grouping scheme, the eligible
vacant codes are listed to find code with least adjacent vacant codes. If
unique result does not exists, the code (among the codes producing same
adjacent vacant codes) with the least elapsed time of the busy neighbors is
used for incoming call.
Keywords: OVSF codes, code/call blocking, OVSF assignment, OVSF reassignment,
OVSF code scattering
Issue 3, Volume 11,
March 2012
Title
of the Paper:
A Cost Effective Approach for WDM Network
Protection under Critical Duct Constraints
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Authors:
D. Sheela, C. Chellamuthu
Abstract: In this paper, protection strategies of WDM networks are viewed from
a cost perspective. The goal is to minimize the network cost while ensuring
the network survivability. In WDM networks, multi fibers are kept in a duct
and that duct can be treated as a link SRLG (shared risk link group). With the
increase in size and number of shared risk link groups, capacity efficiency of
shared-path protection decreases due to SRLG-disjoint constraints. As a
result, a full SRLG failure protection is no longer a practical protection
scheme. In a network, there are always some links with higher degree of usage
compared to other links in the network. In the event of failure of such links,
the survivability of the network is severely affected and these links are
called as critical links. The ducts that carry these critical links are
designated as critical ducts. This paper proposes an approach in which partial
critical duct -disjoint backup path is provided by choosing the backup path
with least number of critical ducts to make the impact of duct failures as low
as possible. A dual-duct infrastructure is presented for these critical ducts
as a solution to reduce the resource requirement and to provide flexibility in
selecting the backup paths. Simulation results show that this scheme offers
better survivability against both single duct and double duct failures with
overall reduction in network cost.
Keywords: Wavelength division multiplexing, Dimensioning, Network protection,
Shared risk link group, Topology, Critical ducts
Title
of the Paper:
Analysis of Subcarrier and Antenna Power
Allocation for MIMO WPMCM System with Sphere Decoder
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Authors:
R. Deepa, K. Baskaran
Abstract: In order to achieve the efficient usage of the available bandwidth
in wireless environments, the best method for real time application would be
combining Multi- Input Multi-Output (MIMO) and Orthogonal Frequency Division
Multiplexing (OFDM) with Cyclic Prefix (CP) together. The OFDM implemented by
using IFFT’s and FFT’s have major drawbacks like ISI (intersymbol
interference), Time and Frequency Synchronization and Carrier Frequency
Offset. To alleviate the above problems wavelet transform is used to generate
the orthogonal carrier. This paper investigates joint subcarrier and antenna
power allocation in WPMCM system. The transmit (antenna) power is allocated
for the proposed combination using the Lagrangian method and compared with the
conventional power allocation scheme. Existing sub-optimal techniques either
use equal power allocation and perform only subcarrier allocation or handle
subcarrier and power allocation separately. In this paper, we propose an
algorithm that performs joint subcarrier and power allocation to reduce the
BER under a total power constraint.
Keywords: MIMO-WPMCM, antenna, sub-carrier power allocation, sphere decoder
Title
of the Paper:
Iterative Multicarrier Detector and LDPC
Decoder for OFDM Systems
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Authors:
Shu-Ming Tseng, Yueh-Teng Hsu, Yi-Rung Peng
Abstract: In this paper, we propose iterative soft-input soft-output (SISO)
multi-carrier detection (inter-carrier interference cancellation) and LDPC
decoding of the OFDM system in the mobile channel. The proposed SISO
multi-carrier detection and sum-product decoding of the LDPC-coded OFDM system
can achieve better error rate performance than previous SISO multi-carrier
detection and BCJR decoding of convolutional coded (CC)-OFDM systems in mobile
channels. The simulation results show that the second iteration improves the
performance significantly and the gain of the third iteration is less. The
advantage of LDPC over CC is more significant when the codeword is longer.
With channel estimation errors, the proposed scheme degrades by 0.5 dB for the
3rd iteration. In addition, the proposed LDPC-OFDM scheme has lower
computational complexity than the CC-OFDM one.
Keywords: inter-carrier interference, turbo principle, OFDM, LDPC, computational
complexity
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