Data transmission systems

With the increasing complexity of the system design, it has become very critical to
enhance system design productivity to meet with the time-to-market demands. Real Time
embedded system designers are facing extreme challenges in underlying architectural
design selection. It involves the selection of a programmable, concurrent, heterogeneous
multiprocessor architecture platform. Such a multiprocessor system on chip (MPSoC)
platform has set new innovative trends for the real-time systems and system on Chip
(SoC) designers. The consequences of this trend imply the shift in concern from
computation and sequential algorithms to modeling concurrency, synchronization and
communication in every aspect of hardware and software co-design and development.
Some of the main problems in the current deep sub-micron technologies characterized by
gate lengths in the range of 60-90 nm arise from non scalable wire delays, errors in signal
integrity and un-synchronized communication. These problems have been addressed by
the use of packet switched Network on Chip (NOC) architecture for future SoCs and
thus, real-time systems. Such a NOC based system should be able to support different levels of quality of service (QoS) to meet the real time systems requirements. It will
further help in enhancing the system productivity by providing a reusable communication
backbone. Thus, it becomes extremely critical to properly design a communication
backbone (CommB) for NOC. Along with offering different levels of QoS, CommB is
responsible directing the flow of data from one node to another node through routers,
allocators, switches, queues and links. In this dissertation I present a reusable component
based, design of CommB, suitable for embedded applications, which supports three types
of QoS (real-time, multi-media and control applications).

This thesis addresses issues faced in the practical implementation of a wireless ad hoc network (WAHN) protocol for data transmission. This study focuses on: (1) Evaluating existing hardware and software options available for the WAHN implementation. (2) Appraising the issues faced while implementing a practical wireless ad hoc protocol. (3) Applying a set of MAC protocol specifications developed for a wireless ad hoc data network to a practical test network. Specific to the above topics of interest, the following research tasks are performed: (1) An elaborate survey and relevant discussions on wireless MAC protocols. (2) A comprehensive study comparing various wireless transceivers is performed. Range, data rate, frequency, interfacing method and cost are the factors compared. (3) A simple, low-cost and low baud-rate transceiver is modified with appropriate interface circuits to support wireless communications. A more advanced transceiver is also considered and used for the software foundation of a practical implementation of the ad hoc and MAC protocols. The studies enable assessing the problems faced during the implementation and suggest solutions to resolve these problems. Further areas for study are also discussed.

Broadband-ISDN Network Architecture and Signaling concepts are described with particular emphasis on Asynchronous Transfer Mode (ATM) technology. A consolidated view of various aspects of B-ISDN/ATM Access and Network Signaling functions, architecture and protocols is presented. Additionally, a suggested evolutionary growth path for the B-ISDN signaling protocols is summarized. This is followed by a high-level comparison of two protocols under consideration for network signaling. The result of this evaluation indicates that the requirements of network signaling are best met by a protocol stack based on SS7 concepts. Finally, a set of future B-ISDN and Multimedia services is presented in context of the requirements they would impose on the signaling protocols. Enhancements to the access signaling protocol are proposed for the support of multiconnection and/or multiparty calls. These extensions/enhancements consist of a set of simplified messages, information elements and procedures based on message flows. Evolution and backward compatibility to existing protocols are taken into account while developing the extensions.

This thesis presents simulation results comparing the performance of different realizations and adaptive algorithms for channel equalization. An attempt is made to study and compare the performance of some filter structures used as an equalizer in fast data transmission over the baseband channel. To this end, simulation experiments are performed using minimum and non minimum phase channel models with adaptation algorithms such as the least mean square (LMS) and recursive least square (RLS) algorithms, filter structures such as the lattice and transversal filters and the input signals such as the binary phase shift keyed (BPSK) and quadrature phase shift keyed (QPSK) signals. Based on the simulation studies, conclusions are drawn regarding the performance of various adaptation algorithms.

This thesis presents simulation results evaluating the performance of blind equalization techniques in the Digital Cellular environment. A new method of a simple zero memory non-linear detector for complex signals is presented for various forms of Fractionally Spaced Equalizers (FSE). Initial simulations are conducted with Binary Phase Shift Keying (BPSK) to study the characteristics of FSEs. The simulations are then extended to complex case via $\pi/$4-Differential Quaterny Phase Shift Keying ($\pi/$4-DQPSK) modulation. The primary focus in this thesis is the performance of this complex case when operating in Additive White Gaussian Noise (AWGN) and Rayleigh Multipath Fading channels.

An Advanced Intelligent Network (AIN) is described and its performance is evaluated in this thesis. First, the AIN architecture is presented. This is followed by the description of the operation and the creation of the telephone services in the AIN architecture. Finally, the AIN architecture is evaluated on the performance of the user-network interface and the network elements, and the expandability and cost effectiveness of the architecture. The result of the evaluation shows that the operation of the telephone services in the AIN architecture are acceptable according to the standards set by Bellcore. Therefore, the AIN architecture meets the objectives set by the telephone operating companies and provides a basis for faster development and deployment of new telephone services in a cost effective manner.

Analytical and simulation performance evaluation results
are presented on the effects of message segmentation and
the validity of the Independence Assumption when applied
to analytically modeling tandem node computer networks.
Simulation results indicate that increasing message
segmentation threshold will increase the network traffic
intensity and consequently the total packet delay. Simulation
and analytical results for total packet delay compared
well only at low traffic intensities. At higher
traffic intensities the discrepancy is due to the
Independence Assumption since it does not account for the
increasing dependency of interarrival times and service
times as packets are made to wait at the nodes.

A Generic Network Executive (GNE) package is presented in
this thesis. It encompasses the strategy and methodology
to follow when implementing data communication software.
GNE was designed for portability and high utilization of
available resources (efficiency). It does not impose
implementation constraints because it does not include
features specific to any system (hardware or operating
system}. It uses a highly concurrent process model with
a pipelined structure . It is not protocol dependent,
rather it is meant to be used to implement low level
services for higher level communic ation protocols. It is
intended to provide interprocess communication in
distributed systems by coupling application programs with
a general purpose packet delivery system, i.e., a datagram service.

A promising next-generation version of service that could be availed from local exchange carriers (LECs) refers to streaming Internet protocol based television (IPTV) programs into subscriber premises via traditional copper pairs. The present study addresses provisioning economically-budgeted and optimally-engineered bit rates (EBRs) in implementing IPTV technology in the local-loop via copper-pairs using the so-called (ADSL2/ADSL2+) technology (with high-speed/large bandwidth considerations plus copper-bonding for bandwidth sharing capabilities). Also studied is the way to extend the backhaul transport of IPTV on copper-lines (plus any other local-loop transmissions that may co-exist) onto an "all-optical" trunk of the inter-office facilities (IOFs) in the edge/core network cloud of the telcos. A model of a core network topology is analyzed for traffic considerations so as to decide on blocking probability at a specified egress node under different conditions of burstiness. The problems posed are analyzed via computations/simulations on Matlab(TM) (v6.5). Inferential remarks are gathered, conclusions are drawn and open-questions yet to be researched are indicated.

In a beacon-enabled network, nodes send beacons when they are ready to transmit or receive messages from the other sensors in their communication range. If the beacons are not synchronized in time, a sensor might receive more than one beacon and hence will not be able to demodulate the beacon, thereby, being isolated from the network. As a result coverage nulls are introduced in the system. To address the above mentioned issues, Motorola Labs have proposed an algorithm for synchronizing the beacons in a wireless personal area network. In this thesis, extensive study of the proposed beacon time synchronization algorithm is done using OPNET as a simulation tool. Simulation is carried out by designing a detailed model of the algorithm using IEEE 802.15.4 as a reference. In depth analysis of the simulation results has been carried out. The results obtained are compared with those of existing time synchronization methods.