Transcript Computer Networks

Lecture 2: Facts of network technologies
developments
Networking Trends
Introduction
Computer networks:
•A computer network is a system of interconnected computers and peripheral
devices.
Communication:
•Communications is about the transfer of information from a sender, across a
distance, to a receiver
•The older forms of communications technology, such as telephones and
radios, use analog signals.
•Computers communicate with digital signals.
Top Networking Research Topics
1. Security
2. Mobile Computing
3. Network-based computing
1. Cloud Computing
2. Grid Computing
3. Internet-of-things (IoT)
4. Voice-over-IP (VoIP)
5. Large-scale wireless networks (Sensors, RFID)
6. High-speed wireless
Mobile Computing
Mobile computing is a generic term describing one's ability to
use technology while moving.
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Mobile computing involves: mobile communication, mobile
hardware, and mobile software.
Mobile Hardware includes mobile devices or device
components.
Mobile software deals with the characteristics and
requirements of mobile applications.
Communication issues in mobile computing include ad hoc
and infrastructure networks as well as communication
properties, protocols, data formats and the existing technologies.
Mobile Computing: Items
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There are at least three different classes of mobile computing items:
portable computers, compacted lightweight units including a full character
set keyboard and primarily intended as hosts for software that may be
parameterized, as laptops, notebooks, notepads, etc.
mobile phones including a restricted key set primarily intended but not
restricted to for vocal communications, as cell phones, smart phones,
phonepads, etc.
wearable computers, mostly limited to functional keys and primarily
intended as incorporation of software agents, as watches, wristbands,
necklaces, keyless implants, etc.
The existence of these classes is expected to be long lasting, and
complementary in personal usage, none replacing one the other in all
features of convenience..
Mobile Computing: Devices and
Limitations
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Devices
Many types of mobile computers have been introduced since the 1990s
including the:
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Personal digital assistant/enterprise digital assistant
Smartphone
Tablet computer
Ultra-Mobile PC
Wearable computer
Limitations
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Range & Bandwidth
Security standards
Power consumption
Transmission interferences
Potential health hazards
Human interface with device
Internet-based technologies and
services: VoIP
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VoIP
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Voice over Internet Protocol (VoIP) is a general term for a
family of transmission technologies for delivery of voice
communications over IP networks such as the Internet
or other packet-switched networks.
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Other terms frequently encountered and synonymous with VoIP
are IP telephony, Internet telephony, voice over broadband
(VoBB), broadband telephony, and broadband phone.
VoIP
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Internet telephony refers to communications services including:
voice, fax, and voice-messaging applications-that are
transported via the Internet, rather than the public switched
telephone network (PSTN).
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The basic steps involved in originating an Internet telephone
call are:
 conversion of the analog voice signal to digital format ,
and
 compression/translation of the signal into Internet
protocol(IP) packets for transmission over the Internet;
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the process is reversed at the receiving end.
VoIP
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VoIP systems employ session control protocols to control the
set-up and tear-down of calls as well as audio codes which
encode speech allowing transmission over an IP network as
digital audio via an audio stream.
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Codec use is varied between different implementations of VoIP
some implementations rely on narrowband and compressed
speech, while others support high fidelity stereocodes
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Cloud Computing
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Cloud computing is the
delivery of computing as
a service rather than a
product, whereby shared
resources, software, and
information are provided
to computers and other
devices as a utility (like
the electricity grid) over a
network (typically the
Internet). Clouds can be
classified as public,
private or hybrid.
Cloud Computing
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Cloud computing relies on sharing of resources to achieve
coherence and economies of scale, similar to a utility (like
the electricity grid) over a network.
At the foundation of cloud computing is the broader
concept of converged infrastructure and shared services.
Cloud computing, or in simpler shorthand just "the cloud",
also focuses on maximizing the effectiveness of the
shared resources.
Cloud resources are usually not only shared by multiple
users but are also dynamically reallocated per demand.
This can work for allocating resources to users.
The Internet of Things
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The Internet of Things (IoT)
refers to the interconnection
of uniquely identifiable
embedded computing-like
devices within the existing
Internet infrastructure.
The Internet of things
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We have passed the threshold where more things are connected
to the Internet than people.
The transition to IPv6 also supports seemingly limitless
connectivity.
Cisco IBSG predicts the number of Internet-connected things
will reach 50 billion by 2020, which equates to more than six
devices for every person on Earth.
Many of us in the developed world already have three or more
full-time devices connected to the Internet when factoring in
PCs, smartphones, tablets, television devices and the like.
The Internet of Things
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Things, in the IoT, can refer to a wide
variety of devices such as heart
monitoring implants, biochip
transponders on farm animals,
automobiles with built-in sensors, or
field operation devices that assist
fire-fighters in search and rescue.
Future IoT? IoT of sensor networks,
using low-power sensors that
"collect, transmit, analyze and
distribute data on a massive scale,"
says Evans.
The Internet of Things
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Typically, IoT is expected to offer advanced connectivity
of devices, systems, and services that goes beyond
machine-to-machine communications (M2M) and covers a
variety of protocols, domains, and applications.
IoT Applications :
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Environmental Monitoring, Infrastructure Management,
Industrial Applications, Energy Management, Medical and
Healthcare Systems, Building and Home Automation, Transport
Systems, Large Scale Deployments
IoT Trends:
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Intelligence, Architecture, Complex system
Wireless Sensor Networks (WSNs)
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A sensor network is a wireless network that consists of
thousands of very small nodes called sensors.
Base station
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Figure 1: Architecture of wireless sensor networks
Wireless Sensor Networks (cont.)
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WSN Sensors are equipped with sensing, limited
computation, and wireless communication capabilities.
Typical hardware components of a sensor node in wireless sensor networks
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WSNs Applications
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WSNs Applications
WSNs Challenges
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Limited Sensor Resources
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Networking Challenges
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Limited bandwidth, routing, multi-hop communication, mobility, topology
control, large no. of sensors, frequent node on/off, etc.
Environment/Application-Driven Challenges
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Battery power, computation capability, memory, etc.
Requirements, extreme conditions, interference, etc.
Other Challenges
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Security, synchronization, localization, deployment..
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