8 research outputs found
UNIFIED ANALYSIS OF TWO-HOP COOPERATIVE AMPLIFY-AND-FORWARD MULTI-RELAY NETWORKS
ABSTRACT This article develops an extremely simple and tight closed-form approximation for the moment generating function (MGF) of signal-to-noise ratio (SNR) for two-hop amplify-and-forward relayed paths over generalized fading environments. The resulting expression facilitates efficient analysis of twohop cooperative amplify-and-forward (CAF) multi-relay networks over a myriad of stochastic channel models (including mixed-fading scenarios where fading statistics of distinct links in the relayed path may be from different family of distributions). The efficacy of our proposed MGF expression for computing the average symbol error rate (ASER), outage probability, and the ergodic capacity (with limited channel side-information among cooperating nodes) is also studied. Numerical results indicate that the proposed MGF expression tightly approximates the exact MGF formulas and outperforms the existing MGF of lower and upper bounds of the half-harmonic mean (HM) SNR, while overcoming the difficulties associated in deriving a
Performance of turbo multi-user detectors in space-time coded DS-CDMA systems
Includes bibliographical references (leaves 118-123).In this thesis we address the problem of improving the uplink capacity and the performance of a DS-CDMA system by combining MUD and turbo decoding. These two are combined following the turbo principle. Depending on the concatenation scheme used, we divide these receivers into the Partitioned Approach (PA) and the Iterative Approach (IA) receivers. To enable the iterative exchange of information, these receivers employ a Parallel Interference Cancellation (PIC) detector as the first receiver stage
Intelligent Circuits and Systems
ICICS-2020 is the third conference initiated by the School of Electronics and Electrical Engineering at Lovely Professional University that explored recent innovations of researchers working for the development of smart and green technologies in the fields of Energy, Electronics, Communications, Computers, and Control. ICICS provides innovators to identify new opportunities for the social and economic benefits of society.  This conference bridges the gap between academics and R&D institutions, social visionaries, and experts from all strata of society to present their ongoing research activities and foster research relations between them. It provides opportunities for the exchange of new ideas, applications, and experiences in the field of smart technologies and finding global partners for future collaboration. The ICICS-2020 was conducted in two broad categories, Intelligent Circuits & Intelligent Systems and Emerging Technologies in Electrical Engineering
Recent Advances in Wireless Communications and Networks
This book focuses on the current hottest issues from the lowest layers to the upper layers of wireless communication networks and provides "real-time" research progress on these issues. The authors have made every effort to systematically organize the information on these topics to make it easily accessible to readers of any level. This book also maintains the balance between current research results and their theoretical support. In this book, a variety of novel techniques in wireless communications and networks are investigated. The authors attempt to present these topics in detail. Insightful and reader-friendly descriptions are presented to nourish readers of any level, from practicing and knowledgeable communication engineers to beginning or professional researchers. All interested readers can easily find noteworthy materials in much greater detail than in previous publications and in the references cited in these chapters
Interference mitigation techniques for optical attocell networks
The amount of wireless data traffic has been increasing exponentially. This results in the shortage
of radio frequency (RF) spectrum. In order to alleviate the looming spectrum crisis, visible
light communication (VLC) has emerged as a supplement to RF techniques. VLC uses light
emitting diodes (LEDs) for transmission and employs photodiodes (PDs) for detection. With
the advancement of the LED technology, LEDs can now fulfil two functions at the same time:
illumination and high-speed wireless communication. In a typical indoor scenario, each single
light fixture can act as an access point (AP), and multiple light fixtures in a room can form a
cellular wireless network. We refer to this type of networks as ‘optical attocell network’. This
thesis focuses on interference mitigation in optical attocell networks.
Firstly, the downlink inter-cell interference (ICI) model in optical attocell networks is investigated.
The conventional ray-tracing channel model for non-line-of-sight (NLOS) path is studied.
Although this model is accurate, it leads to time-consuming computer simulations. In order
to reduce the computational complexity, a simplified channel model is proposed to accurately
characterise NLOS ICI in optical attocell networks. Using the simplified model, the received
signal-to-interference-plus-noise ratio (SINR) distribution in optical attocell networks can be
derived in closed-form. This signifies that no Monte Carlo simulation is required to evaluate
the user performance in optical attocell networks.
Then, with the knowledge of simplified channel model, interference mitigation techniques using
angle diversity receivers (ADRs) are investigated in optical attocell networks. An ADR
typically consists of multiple PDs with different orientations. By using proper signal combining
schemes, ICI in optical attocell networks can be significantly mitigated. Also, a novel
double-source cell configuration is proposed. This configuration can further mitigate ICI in
optical attocell networks in conjunction with ADRs. Moreover, an analytical framework is
proposed to evaluate the user performance in optical attocell networks with ADRs.
Finally, optical space division multiple access (SDMA) using angle diversity transmitters is
proposed and investigated in optical attocell networks. Optical SDMA can exploit the available
bandwidth resource in spatial dimension and mitigate ICI in optical attocell networks.
Compared with optical time division multiple access (TDMA), optical SDMA can significantly
improve the throughput of optical attocell networks. This improvement scales with the number
of LED elements on each angle diversity transmitter. In addition, the upper bound and
the lower bound of optical SDMA performance are derived analytically. These bounds can
precisely evaluate the performance of optical SDMA systems. Furthermore, optical SDMA
is shown to be robust against user position errors, and this makes optical SDMA suitable for
practical implementations
Research reports: 1991 NASA/ASEE Summer Faculty Fellowship Program
The basic objectives of the programs, which are in the 28th year of operation nationally, are: (1) to further the professional knowledge of qualified engineering and science faculty members; (2) to stimulate an exchange of ideas between participants and NASA; (3) to enrich and refresh the research and teaching activities of the participants' institutions; and (4) to contribute to the research objectives of the NASA Centers. The faculty fellows spent 10 weeks at MSFC engaged in a research project compatible with their interests and background and worked in collaboration with a NASA/MSFC colleague. This is a compilation of their research reports for summer 1991
Computation offloading for algorithms in absence of the Cloud
Mobile cloud computing is a way of delegating complex algorithms from a mobile
device to the cloud to complete the tasks quickly and save energy on the mobile device.
However, the cloud may not be available or suitable for helping all the time. For
example, in a battlefield scenario, the cloud may not be reachable. This work considers
neighbouring devices as alternatives to the cloud for offloading computation and presents
three key contributions, namely a comprehensive investigation of the trade-off between
computation and communication, Multi-Objective Optimisation based approach to
offloading, and Queuing Theory based algorithms that present the benefits of offloading
to neighbours.
Initially, the states of neighbouring devices are considered to be known and the decision
of computation offloading is proposed as a multi-objective optimisation problem. Novel
Pareto optimal solutions are proposed. The results on a simulated dataset show up to
30% increment in performance even when cloud computing is not available. However,
information about the environment is seldom known completely. In Chapter 5, a realistic
environment is considered such as delayed node state information and partially connected
sensors. The network of sensors is modelled as a network of queues (Open Jackson
network). The offloading problem is posed as minimum cost problem and solved using
Linear solvers. In addition to the simulated dataset, the proposed solution is tested on a
real computer vision dataset. The experiments on the random waypoint dataset showed
up to 33% boost on performance whereas in the real dataset, exploiting the temporal
and spatial distribution of the targets, a significantly higher increment in performance
is achieved