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Introduction to Communication Technology

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     Introduction to Communication Technology




                                An initiative funded by the




                                        Facilitated by




Learning objectives                                                 of        Communication
Technologies

At the end of the program participants will be able to
     Relate to the different communication technologies with regards
       conservation and development.
     Acquire knowledge on the fundamental principles of basic radio
       communications.
     Apply the relevant communication technologies to their everyday use in
       the workplace.
     Be      confident                                and motivated in the use of
       the
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           communication technologies.


Learning Approach

Information will be disseminated through instruction, but with a more interactive
approach through discussions of personal experiences with information
technology. Practical hands on exercises will be used so as to enhance and
further appreciate the workings of information technologies. A basic appreciation
of the theory of these technologies will be explored.




     Table of Contents
  Introduction to Communication Technology ......................................................................i
     Learning objectives of Communication Technologies ................................................. ii
Session 1: Basic Radio Physics ...............................................................................................1
  1.1 Learning Objective: To get knowledge of the fundamental principles of basic radio
  communications....................................................................................................................1
  1.2 Content ............................................................................................................................1
     1.2.1 Voice VS Data Communication ............................................................................1
  1.3Factors affecting choice of transmission media ............................................................2
  1.4 The Electromagnetic (EM) Spectrum ..........................................................................2
  1.5 Propagation of Electromagnetic Waves........................................................................5
     1.5.1 Absorption ...............................................................................................................6
     1.5.2 Reflection ................................................................................................................6
     1.5.3 Diffraction ...............................................................................................................6
     1.5.4 Interference .............................................................................................................7
  1.6 Line-of-Sight Microwave ..............................................................................................7
  1.7 Applications of Radio technologies ..............................................................................8
  1.8 Wireless Fidelity Wi-Fi or 802.11 networking ............................................................9
  1.9Satellite Communication ..............................................................................................10
Session 2: Introduction to Voice and Data Communications ..............................................12
  2.1 Learning Objective: To understand Data and Voice Communications ....................12
  2.2 Voice Transmission......................................................................................................12
     2.2.1 Public Switched Telephone Network (PSTN) – “landline” ...............................12
  2.3 PSTN Services..............................................................................................................13
     2.3.1 Dialup ....................................................................................................................13
     2.3.2 Faxing ....................................................................................................................13
  2.4 Integrated Services Digital Network (ISDN) .............................................................13

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  2.5Asynchronous Transfer Mode (ATM) .........................................................................14
  2.6X25 packet network ......................................................................................................14
  2.7Asymmetric Digital Subscriber Line (ADSL).............................................................14
  2.8 GSM (Global System for Mobile Communications) ................................................16
     2.8.1 The Mobile Station (MS) .....................................................................................17
     2.8.2 The Base Station Subsystem (BSS) .....................................................................17
     2.8.3 The Base Transceiver Station (BTS) ...................................................................17
     2.8.4 The Base Station Controller (BSC) .....................................................................18
  2.9 Case study .....................................................................................................................19
  2.10GPRS ...........................................................................................................................19
  2.11 Data Transmission......................................................................................................20
  2.11Features of OSI............................................................................................................21
  2.13 Transmitting data via the Internet .............................................................................22
     2.14.1 Transmission Control Protocol ..........................................................................22
     2.14.2 Internet Protocol (IP) .........................................................................................23
  2.15 Bushmail .....................................................................................................................24
Session 3: Tools for Communication ....................................................................................25
  3.1 Learning Objective: Summarise the use of the communication tools ......................25
  3.2 Content ..........................................................................................................................25
  3.3 Relevance of Communication Technologies ..............................................................26
Session 4: Practical .................................................................................................................28
  4.1 Learning Objective: Attain the skill of using a data and a voice application ...........28
  4.2 Practical A ....................................................................................................................28


Table of Figures
Figure 1: Diffraction over a mountaintop ...............................................................................7
Figure 2: A sketch of an LOS microwave radio relay system. ..............................................8
Figure 3: Dynamic Pocket Solution. ......................................................................................9
Figure 4: PSTN Network .......................................................................................................12
Figure 5: GSM System Architecture .....................................................................................17
Figure 6: GPRS Data Transfer ...............................................................................................20
Figure 7: Bushmail Connection .............................................................................................24



List of Tables
Table 1: Uses of Rays...............................................................................................................3
Table 2: EM Spectrum .............................................................................................................4
Table 3: Features of OSI ........................................................................................................21
Table 4: Use of Communication Tools .................................................................................25

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Session 1: Basic Radio Physics
1.1    Learning Objective: To get knowledge of the fundamental principles of basic
radio communications.

Framework:

      Introduce the electromagnetic spectrum
      Define Wavelength, wave velocity and frequency and wave
      Discuss the frequency ranges using the electromagnetic spectrum
      The propagation of electromagnetic waves
      The effects of absorption, reflection, diffraction and interference on
       electromagnetic waves
      Concepts in Radio propagation, Free Space Loss, Fresnel Zones, Line of
       sight and (Huygens Principle)
      Radio Waves using WiFi as an example

1.2     Content
Communication is a way of conveying information, by means of a written code or
verbal means. ‗Technology changes, but communication lasts‘, the availability of
communication technologies has made a great impact on human lives, but the
challenges of the modern environment (social, political, economic and
environmental) all mean, it is increasingly important to take advantage of these
tools to share information and collaborate effectively.

1.2.1 Voice VS Data Communication

Tele-Communications can therefore be basically grouped into two -voice & data
―Tele‖ means distant, hence telecommunication means communication at a
distance. Three basic components that comprise a full communication channel:

1. The Sender – A transmitter encodes the message in a language that can be
understood by the receiver.

2. The Receiver –decodes the message.

3. The Medium – Air, copper wires, optical fibre. These carry the message across
from the sender to the receiver.

In telecommunications a transmission system is a system that transmits a signal
from one place to another. The signal can be an electrical, optical or radio signal.

As signals are being transmitted there is loss of signal power (attenuation),
changes in shape of signal (distortion) and they can pick up undesired signals
(noise). In order to receive the same transmitted signals at the receiver end,
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some transmission systems contain repeaters, which amplify a signal prior to re-
transmission, or regenerators, which attempt to reconstruct and re-shape the
coded message before re-transmission. Repeaters enable the receiver to get the
message intact thereby minimising distortion.

1.3   Factors affecting choice of transmission media

Information bandwidth – Bandwidth is simply a measure of frequency range. It is
easy to see that the bandwidth we define here is closely related to the amount of
data you can transmit within it - the more room in frequency space, the more data
you can fit in at a given moment. The term bandwidth is often used for something
we should rather call a data rate, as in ―my Internet connection has 1 Mbps of
bandwidth‖, meaning it can transmit data at 1megabit per second.

In communications, fibre optics have an infinite bandwidth, whereas radio
systems have very limited information bandwidth. It is for this reason that
frequency bands 2GHz and above is used for the PSTN and private network
applications. In terms of licensing and sharing, metallic and optic media do not
require licensing, whereas radio requires licensing and it is a shared resource.
Radio has a high susceptibility to noise and variability in performance.
Interference is notable in radio systems than other media. It is also charecterised
by delays, which are notable in some radio systems. Satellite systems introduce
a 250ms delay in one hop.


Radio systems have some draw backs but it has advantages over other types of
media
   Less expensive to implement
   Less vulnerable to vandalism
   Not susceptible to accidental cutting of links
   Often more suited to crossing rough terrains
   Often more practical to highly urbanised areas
   Back up to fibre optic cables


It is imperative to note that radio communication uses a finite band of the
electromagnetic spectrum.

1.4   The Electromagnetic (EM) Spectrum

Electromagnetic waves span a wide range of frequencies and similarly a wider
range of Wavelengths. This range of frequencies and wavelengths is called the

Electromagnetic Spectrum.

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The EM Spectrum is defined as
    A full range of frequencies from Radio to Gamma rays.
    The name given to a bunch of the types of radiation?

Radiation is energy that travels and spreads out as it goes.

The part of the spectrum most familiar to humans is probably light, the visible
portion of the electromagnetic spectrum. Ultraviolet is (on the higher frequencies
side of visible light) and Infrared (on the lower frequencies side of visible light)
and there are many others.

 Radio is the term used for the portion of the electromagnetic spectrum in which
waves can be generated by applying alternating current to an antenna. This is
true for the range from 3 Hz to 300 GHz, but in the more narrow sense of the
term, the upper frequency limit would be 1 GHz. When talking about radio, many
people think of FM radio, which uses a frequency around 100 MHz. In between
radio and infrared we find the region of Microwaves, these have frequencies from
about 1 GHz to 300 GHz, and wavelengths from 30 cm to 1 mm. The most
popular use of microwaves might be the microwave oven. Most other parts of the
electromagnetic spectrum are tightly controlled by licensing legislation, with
license values being a huge economic factor. This goes especially for those parts
of the spectrum that are suitable for broadcast (TV, radio) as well as voice and
data communication.

Table 1: Uses of Rays




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EM            Frequency Wavelength Energy                       Application
Gamma         Highest   Shortest   Highest                      Used by Scientist to discover
Rays                                                            what matter is made of
X- Rays                                                         (Nuclear Power)
Ultra Violet                                                    Used by Doctors to see bones
(UV)                                                            Emitted by Sun, causes
Visible light                                                   burning of skin
Infrared                                                        Seen by the human eye
Microwave                                                       Used as Heat .In space, maps
Radio                                                           dust between stars
                                                                Used to cook popcorn, and
                                                                also in        the study of
                                                                astronomy
                 Lowest          Longest           Lowest       Aircraft and Shipping Band,
                                                                AM/FM radios, TV



The Electromagnetic Spectrum Table


The EM spectrum can be expressed in terms of Energy (photons), wavelength or
frequency.

Table 2: EM Spectrum




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Source: http://en.wikipedia.org/wiki/Image:Electromagnetic-Spectrum.png


Wavelength (λ) is the distance between adjacent peaks in a series of periodic
wave. Unit of measurement (meter- m)

Frequency (f) is the property of a wave that describes how many wave cycles
pass by in a period of a time. Unit of measurement (Hertz – Hz)

Wave Speed (c) is the speed of light and is approximately 3X108 m/s

Relationship between frequency and wavelength and wave speed
Wave speed (c) = Frequency (f) x Wavelength (λ)

NB. The longer the wavelength, the further it goes
The longer the wavelength, the better it goes through and around things
The shorter the wavelength, the more data it can transport


1.5    Propagation of Electromagnetic Waves

Electromagnetic Waves as they propagate are subject to


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      Absorption
      Reflection
      Interference


1.5.1 Absorption

Radio waves get dampened or weakened as they pass through any matter
whether it is solid, liquid or gas, as energy is transferred to the medium they are
travelling through. The absorption of light during wave propagation is often called
attenuation which in other words is the degradation of signal power.

There is strong Radio wave absorption in conducting materials, metals, and
water in all its forms. Intermediate absorption is found in stones, bricks, concrete
(depending on the exact parameters of materials). The same goes for wood /
trees (depending on the water concentration). With radio implants (tracking
devices) it is essential to note that the terrain, vegetation and power lines have
an effect on the reception. Implants can either be on the horn or the abdominal
cavity of an animal. Abdominal implants (where radio collars are unsuitable) can
be attached on the following animals, porcupine, bush pig, warthog and pythons.
Horn implants are used on black and white rhino.


1.5.2 Reflection
Radio waves are reflected when they come in contact with materials that are
suited for radio waves, the main sources of reflection are metal and water
surfaces. Reflection rule states that the angle at which a wave hits a surface is
the same angle at which it gets deflected.

1.5.3 Diffraction
Diffraction is the apparent bending of waves when hitting an object. It is the
effect of ―waves going around corners‖. Microwaves, with a wave-length of
several centimeters, will show the effects of diffraction when they hit walls,
mountain peaks, and other obstacles. It seems as if the obstruction causes the
wave to change its direction and go around corners.




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Figure 1: Diffraction over a mountaintop
Source: Wireless Book pdf

1.5.4 Interference
In wireless technology the term ―interference‖ is generally used to describe,
disturbance of radio signals from other Radio Frequency sources e.g.
neighbouring radio channels. In communications and especially in
telecommunications, interference is anything, which alters, modifies, or disrupts a
message as it travels along a channel between a source and a receiver.

1.6    Line-of-Sight Microwave
The term line of sight, often abbreviated as LOS, is quite easy to understand
when talking about visible light: if we can see a point B from point A where we
are, we have line of sight. Simply draw a line from A to B, and if nothing is in the
way, we have line of sight. In communications, Line-of-sight (LOS) is a straight
line between the transmitting and receiving antennas. It is important to keep the
zone around the direct line between signal and receiver as clear as possible

Line-of-microwave provides a comparative broadband connectivity of 622Mbps
over a single link or a series of links in tandem compared to 100M on copper.

On conventional LOS microwave links, the length of a link is a function of
antenna height. In this regard, the higher the antenna, the further the reach and
therefore the wider the coverage of connectivity.




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Figure 2: A sketch of an LOS microwave radio relay system.

Source: Wiley IEEE Press Fundamentals of Telecommunications 2 nd Edition Apr
2005

1.7     Applications of Radio technologies

Radio tracking is used to study migration patterns of different animal species.
A tracking device (collar, back-pack or implant) is attached onto the animal and
this sends out radio signals to and from the animal to a transceiver normally at
the park management offices.

Factors affecting the choice of tracking devices
    Self powered
    Low power consumption
    Long system lifetime.
    Light to carry
    Should withstand the different weather conditions, i.e. should be highly
      reliable.
    The zone to be covered in terms of coverage area (sufficient sensing
      coverage)
    The number of frequency channels available and channel spacing

Rangers can obtain the following by studying patterns obtained from the tracking
information
     Migration seasons and patterns.
     Identify possible reasons for decline in a particular species.
     Assessment of human-wildlife conflict therefore looks for ways to reduce
      the human-wildlife conflict.
     Better planning and park management.
     Enhancement of conservation education to locals or community.

Examples
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Wildtrack program collects and analyses location data, speed, the distance of
movement and interaction between animals.




Figure 3: Dynamic Pocket Solution.
Source: t4cd resource data disk

Radio Tracking Equipment developed by Africa Wildlife tracking targets the
following species elephants, leopards, cheetahs, buffalos, lions and a lot more.
www.awt.co.za



1.8     Wireless Fidelity Wi-Fi or 802.11 networking

A wireless network uses radio waves, just like cell phones, televisions and radios
do. Wireless networks are easy to set up and inexpensive. They are also
unobtrusive (do not attract attention). One wireless router can allow multiple
devices to connect to the Internet.

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A computer's wireless adapter translates data into a radio signal and transmits it
using an antenna. A wireless router receives the signal and decodes it. It sends
the information to the Internet using a physical, wired Ethernet connection.
The process also works in reverse, with the router receiving information from the
Internet, translating it into a radio signal and sending it to the computer's wireless
adapter. WiFi radios transmit at frequencies of 2.4 GHz or 5GHz. The higher
frequency allows the signal to carry more data. 802.11b transmits in the 2.4 GHz
frequency band of the radio spectrum. It can handle up to 11 megabits of data
per second. 802.11g also transmits at 2.4 GHz, but it's a lot faster than 802.11b -
it can handle up to 54 megabits of data per second. 802.11a transmits at 5GHz
and can move up to 54 megabits of data per second.

The area covered by one or several access points (AP) is called a hotspot. An
AP broadcasts its SSID (Service Set Identifier, "Network name") via packets that
are called beacons, which are usually broadcast every 100 ms. If two APs of the
same SSID are in range of the client, the client firmware might use signal
strength to decide which of the two APs to make a connection to. Wi-Fi cannot do
collision detection, and instead uses a packet exchange (RTS/CTS used for
Collision Avoidance or CA) to try to avoid collisions.

1.9       Satellite Communication

Satellites are highly specialized wireless transmitters and receiver placed in orbit
around the earth. They can relay as many signals at the same time, to and from
the earth with messages as simple as data messages to as complex as TV
signals. Satellite communications are used to:

         Radio and TV broadcast
         Internet Services
         Data and Broadband and multi-media services
         Fixed position telephony
         Mobile Communications

Satellite phones send radio signals direct to the satellite then down to an earth
station from where the call can be connected to the public switched telephone
network. They are used where the fixed, or wired lines and or cellular coverage is
not available. A satellite phone requires line of sight with the satellite. This means
the satellite antennae should be positioned in such a way that it is facing the
satellite. Maximum signal strength can be obtained by rotating the antennae lid to
a position that receives the signal.

Example 1


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Satellite Collars (tracking devices attached to an animal) are based on mobile
global two way communication using two way data satellite communications. By
connecting to Internet, Park Rangers have access to customised maps, historical
data and near to real time positions of animals.

Satellite tracking uses a platform transmitter terminal (PTT) attached to the
animal which sends radio signals to the ARGOS Satellite system. The satellite
calculates the animal‘s location and then relays the information to the ground
service stations which sends location data to researchers in a remote location.
ARGOS satellite system is the most widely used tracking systems. Inmarsat is
also used for tracking.


Example 2
Broadband Global Area Network: With a BGAN satellite terminal and a telephone
handset or headset and a Laptop or PC, a satellite up link is established.

BGAN features:
   An easy to use interface
   Clear step-by-step instructions on pointing the terminal and setting up a
     satellite connection
   Ability to customize the data connection options to match ones application
     requirements
   Ability to pre-configure user access settings, enabling one to restrict
     access to Streaming IP services, for example
   Convenient online access to account and billing information
   Personal and corporate versions
   Access to text messaging and telephony features


Session 2: Introduction to Voice and Data Communications
2.1   Learning Objective: To understand Data and Voice Communications

Framework:
    Basic Voice Transmission, Fixed (PSTN) and Mobile
    Basic Data Transmission, OSI layer, TCP/IP protocol

2.2   Voice Transmission

2.2.1 Public Switched Telephone Network (PSTN) – “landline”
PSTN is a circuit-switched network that is used primarily for voice
communications worldwide in much the same way that the Internet is the network
of the world‘s public IP-based data (packet-switched) networks. Originally it was
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a network of fixed-line analogue telephone systems, but it is now almost entirely
digital although the signal coming out of the phone where the user is connected
is analogue.

Verbal communication is usually transmitted over a twisted pair cable as an
analogue signal. At the central office this analogue signal is usually digitised, ,
yielding a 64 kb/s data stream (DS0). This explains why a dial up cannot exceed
56K.




Figure 4: PSTN Network

Source: http://www.althosbooks.com/intopuswtene.html

Features of PSTN

      The majority of work and expense of the phone system is the wiring
       outside the central office, or the Outside plant. In the middle 20 th century,
       each subscriber telephone number required an individual pair of wires
       from the switch to the subscriber‘s phone.
      The outside plant is expensive to maintain and replace
      To reduce the expense of outside plant, some companies use ―pair gain‖
       devices to provide telephone service to subscribers. Pair gain means that
       from one pair of wires we can have about 8 other devices using that single
       pair.
      A large database tracks information about each subscriber pair and the
       status of each jumper.
      Each subscriber pair is addressed uniquely by a telephone number
       defined by ITU-T, E.163/E.164 numbering plan.
      Dial up speeds can be achieved at 56K for data transmission

PSTN is a fixed network and is slowly being the less favored, as other forms of
communication such as SMS, email, VOIP are taking a centre stage. There are
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also private networks run by large companies, which are linked, to the PSTN only
through limited gateways, like a large private branch exchange (PBX) system.

2.3      PSTN Services

2.3.1 Dialup
Dialup enables web browsing and other features related to the Internet such as
chatting, Skype, and email. A modem changes the digital form of data to
analogue signals (Modulation) that is compatible on PSTN lines and converts it
back to digital at the receiving end (DEModulation).

2.3.2 Faxing
Documents can be sent over PSTN by dialling the receiver fax number.

2.4    Integrated Services Digital Network (ISDN)
This is a circuit-switched telephone network system, designed to allow digital
transmission of voice and data over ordinary telephone copper wires, resulting in
better quality and higher speeds than that available with the PSTN system.

In ISDN, there are two types of channels, B (for ―Bearer‖) and D (for ―Delta‖). B
channels are used for data (which may include voice), and D channels are
intended for signalling and control (but can also be used for data).

There are three ISDN implementations.
   1. Basic Rate Interface (BRI) , also known as Basic Rate Access (BRA) —
      consists of two B channels, each with bandwidth of 64 kbit/s, and one D
      channel with a bandwidth of 16 kbit/s. Together these three channels can
      be designated as 2B+D.

      2. Primary Rate Interface (PRI), also known as Primary Rate Access (PRA)
         — contains of a greater number of B channels and a D channel with a
         bandwidth of 64 Kbit/s. The number of B channels for PRI varies
         according to the nation: in North America and Japan it is 23B+1D, with an
         aggregate bit rate of 1.544 Mbit/s (T1); in Europe and Australia it is
         30B+1D, with an aggregate bit rate of 2.048 Mbit/s (E1).


      3. Broadband Integrated Services Digital Network (BISDN) is another ISDN
         implementation and it is able to manage different types of services at the
         same time. It is primarily used within network backbones and employs
         asynchronous transfer mode.

2.5      Asynchronous Transfer Mode (ATM)

Another alternative ISDN configuration can be used in which the B channels of
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an ISDN basic rate interface are bonded to provide a total duplex bandwidth of
128 Kbit/s. This precludes use of the line for voice calls while the internet
connection is in use. The D channel can also be used for sending and receiving
X.25 data packets, and connection to X.25 packet network.

2.6   X25 packet network

X25 is a packet switched data protocol. The packet switching nodes has multiple
choices for routing data packets. If a particular route becomes congested or has
degraded operation, a packet is sent on another route. Packets are reassembled
at the receiving end to give the transmitted data.

2.7   Asymmetric Digital Subscriber Line (ADSL)

This is a form of DSL, a data communications technology that enables faster
data transmission over copper telephone lines than a conventional modem can
provide. ADSL can only be used over short distances, typically less than 5 km.

Once the signal reaches the telephone company‘s local office, the ADSL signal is
stripped off and immediately routed onto an internet network, while any voice-
frequency signal is switched into the phone network. This allows a single
telephone connection to be used for both ADSL and voice calls at the same time
without any interference.

The distinguishing characteristic of ADSL over other forms of DSL is that
the volume of data flow is greater in one direction than the other, i.e. it is
asymmetric. Higher speed direction for the “download” (8M) from the
Internet but a lower speed (1M) in the other direction. With standard ADSL,
the band from 25.875 kHz to 138 kHz is used for upstream communication,
while 138 kHz – 1104 kHz is used for downstream communication2.8 GSM
(Global System for Mobile Communications)

The Global System for Mobile Communications (GSM) system is a global digital
radio system that uses Time Division Multiple Access (TDMA) technology .We
have the GSM900 system where the frequency used is 900 MHz, GSM1800
frequency band used 1800MHz and GSM1900 frequency band used 1900MHz.
These three systems differ primarily in the air interface. Besides using different
frequency bands, they use a microcellular structure (i.e. a smaller coverage
region for each radio cell). This makes it possible to reuse frequencies at closer
distances, enabling an increase in subscriber density. The disadvantage is the
higher attenuation of the air interface due to the higher frequency.

The benefits of GSM include:
    Support for international roaming
    Distinction between user and device identification
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      Excellent speech quality
      Internetworking (e.g. with ISDN, DECT)
      Extensive security features such as blacklisting all stolen handsets such
       that they become unusable in the network.


GSM stands out from other technologies with its wide range of services:
   Telephony
   Asynchronous and synchronous data services (2.4/4.8/9.6 kbit/s)
   Access to packet data network (X.25)
   Telematic services (SMS, fax, videotext, etc.)
   Many value-added features (call forwarding, caller ID, voice mailbox)
   E-mail and Internet connections

Asynchronous data services use the start stop transmission, whereby the
beginning of a character and end of a character, is signified by a start and stop
bit respectively. Synchronous data service has a reduced overhead, but employs
signals that will indicate the start of a data frame and when it will end.
Asynchronous and synchronous data transmission does not realise higher
transmission speeds because of the control overhead.




Figure 5: GSM System Architecture

Source: Pocket Guide for Fundamentals and GSM testing by Marc Kahabka

They are characterized as follows:

2.8.1 The Mobile Station (MS)

A mobile station may be referred to as a handset, a mobile, a portable terminal or
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mobile equipment (ME). It also includes a subscriber identity module (SIM) that is
normally removable and comes in two sizes. Each SIM card has a unique
identification number called IMSI (international mobile subscriber identity). In
addition, each MS is assigned a unique hardware identification called IMEI
(international mobile equipment identity).

In some of the newer applications (data communications in particular), an MS
can also be a terminal that acts as a GSM interface, e.g. for a laptop computer.
Besides providing a transceiver (TRX) for transmission and reception of voice
and data, the mobile also performs a number of very demanding tasks such as
authentication, handover, encoding and channel encoding.

2.8.2 The Base Station Subsystem (BSS)
The base station subsystem (BSS) is made up of the base station controller
(BSC) and the base transceiver station (BTS).

2.8.3 The Base Transceiver Station (BTS)
GSM uses a series of radio transmitters called BTSs to connect
                                                                                        Media Report on Killings of
the mobiles to a cellular network. Their tasks include channel
                                                                                        Rare Mountain Gorillas
coding/decoding and encryption/decryption. A BTS is comprised
of radio transmitters and receivers, antennas, the interface to the                     Killings of rare mountain gorillas
PCM facility, etc. The BTS may contain one or more 8                                    in Virunga National Park,
transceivers to provide the required call handling capacity. A cell                     Democratic Republic of Congo
                                                                                        dated 18 January 2007. Two
site may be omni-directional or split into typically three directional
                                                                                        mountain gorillas were killed in
cells.                                                                                  the Democratic Republic of
                                                                                        Congo (DRC)’s Virunga National
2.8.4 The Base Station Controller (BSC)                                                 Park. The gorillas were both
                                                                                        solitary silverback males, from
A group of BTSs are connected to a particular BSC which                                 groups conditioned not to fear
                                                                                        humans. Both were killed within
manages the radio resources for them. Today‘s new and                                   two weeks, and one is believed
intelligent BTSs have taken over many tasks that were previously                        to have been eaten. It is feared
handled by the BSCs. The primary function of the BSC is call                            that others may already have
maintenance. The mobile stations normally send a report of their                        Been killed or are in imminent
                                                                                        danger. Before the attacks, it
received signal strength to the BSC every 480 ms. With this
                                                                                        was thought that just 700
information the BSC decides to initiate handovers to other cells,                       mountain gorillas were left in this
change the BTS transmitter power, etc.                                                  region of Africa, approximately
                                                                                        half of which were to be found in
Example 1                                                                               the Virunga forest block
Cellular Collars (tracking devices), Hawk105 was developed by
                                                                                        It has not been confirmed who is
Africa Wildlife Tracking. The device is fitted to the animal and                        responsible for the killings of the
determines positions accurately within 10m at specified times                           gorillas, but it is unlikely to have
(scheduled daily or weekly), while the animal is in the field.                          been local people, who do not
                                                                                        eat gorillas and have been
The gathered position data is logged and sent to the user                               supportive of conservation work.
                                                                                        Hippos and buffalos have also
immediately. The data is downloaded with Hawk105 software                               suffered from heavy poaching.
                                                                                                       1
                                                                                        Cattle ranching and charcoal
                                                                                        burning activities are posing
                                                                                                       6
                                                                                        further threats to the park itself.
                                     A t4cd Training Manual                             Thousands of local people have
                                                                                        fled their homes and are living in
                                                                                        poor conditions.”
                                                                                        Adapted from flora and fauna
                                                                                        international webpage
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package. When there is no GSM coverage, a VHF beacon transmitter is
activated automatically providing backup for the logged data up to 240 readings.

The battery life depends on the number of readings taken per day. Typic ally with
D type battery, in a good area, battery life is two years with 5 readings per day. It
has remarkable low power consumption. Its basic requirements are cellular
coverage, computer and the Internet.

Example 2
Mobile gamming is one application that can educate the community of
conservation issues. Masabi developed a secure mobile gamming application
that educates on conservation e.g. Silverback. It incorporates platform game
play, as well as accurate facts about gorilla habits. One preconception people
have about gorillas is that they sit around eating bananas, in the game one gorilla
comes up and starts eating a banana, and a pop up bubble comes up to say that
they actually don't eat them, they eat mostly leaves instead.

Players take on the role of a baby gorilla, which develops over eight levels. The
gorilla is separated from its family and has to fend for itself, escape poachers, as
well as forest fires, and raise a family of its own. This application is both fun and
informative.


2.9       Case study

Mobile GSM phones have a great impact on human lives. In developing countries
like Zimbabwe it is no longer a luxury but a necessity even for the folks and
farmers in the rural areas. Small scale entrepreneurs can now contact potential
clients, saving on transport costs and loss of perishable goods when a sale does
not go through. Farmers use mobile handsets for best prices for their crops

Information is disseminated more readily. When an outbreak of foot and mouth
occurs in an area, the agricultural extension officer makes a call to the headman
of the village informing him of the need to vaccinate all animals. The headman
then informs all villagers hence curbing the spread of the disease.

Neighbouring villages are informed when army worms threatens their crops, and
take precautionary measures. Mobile Communications is much cheaper than the
fixed pair gains lines, which was in the reach of a few elite members. With
recycled handsets and prepaid mobile lines, communication has been brought
closer to home.

         An improved communication network increases the effectiveness of
          patrols in protected areas.
         Voice and SMS raises awareness on conservation issues in the
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       community.


2.10   GPRS

General Packet Radio Service (GPRS) provides packed data services to the
Global System for Mobile communications (GSM). It provides a basic solution for
Internet Protocol (IP) communication between Mobile Stations (MS) and the
Internet or corporate Local Area Networks (LAN).

GPRS provides the following services:
   Efficient transport of packets in the cellular network
   Efficient use of scarce radio resources
   Flexible service, with prepaid or postpaid charging based on content,
     volume, or session duration.
   Fast setup and access time
   Simultaneous circuit-switched and packet-switched services, which means
     coexistence without disturbance
   Connectivity to other external Packet Data Networks (PDNs), using IP
     packet data
   WWW server, that is, a local Web server supplying Web pages
   Domain Name System (DNS) server providing translation between host
     names and IP addresses
   E-mail server, that is, a Post Office Protocol version 3 (POP3) / Simple
     Mail Transfer Protocol (SMTP) server providing an Internet e-mail address
     for the end-user
   Wireless Application Protocol (WAP) server


GPRS data transfer is IP based. A message consisting of large quantities of data
is divided into several packets. When these packets reach the destination, they
are stored in data buffers and reassembled to form the original message. The
packet data transmission is thus carried out on an end-to-end basis, including the
radio interface.




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Figure 6: GPRS Data Transfer

Source: GPRS Tutorial Pdf Morgan Doyle Limited


2.11    Data Transmission

Data networks use the Open System Interconnection (OSI) referencing model to
transfer packets between devices. All the processes required for effective
communication are divided into logical groupings called layers.

2.11    Features of OSI

       Allows interoperability of network devices from different vendors ie. it
        provides the basis for connecting open systems for connecting open
        systems for distributed applications processing.
       It‘s a seven layered protocol, which eliminates the ―ripple effect‖ when
        there is a modification in any of the layers.

Table 3: Features of OSI

Application               Provides a user interface between the computer and the
                           user.
                          Runs file, print, message, databases and application
                           services
                          Examples of application services are www, email, financial
                           transactions, internet navigation utilities – Gopher, Google



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Presentation           Presents data to the application layer (translator)
                       Handles processing such as data encryption, compression
                        and data translation and code formatting
                       Ensures that the application layer of another one can read
                        data transferred from the Application layer on one system.
                       Examples of standards – MPEG (Moving Picture Experts
                        Group) for the compression and coding of motion video for
                        CDs. Provides digital storage and bit rates up to 1.5Mbps
                       JPEG (Joint Photographic Experts Group) RTF (Rich Text
                        Format)
Session                Keeps different applications data separate, i.e. dialogue
                        control between devices
                       Responsible for setting up, managing, and tearing down
                        sessions between presentation layer entities
                       Supports different communication modes – simplex, half
                        duplex and full duplex
                       Examples of protocols Network File System
                       Structured Query Language
Transport              Provides reliable or unreliable delivery
                       Performs error correction before retransmission
                       Responsible for end to end connection
                       Examples of Protocols –TCP (Transmission Control
                        Protocol)
                       UDP (User Datagram Protocol)
Network                Provides logical addressing, hence routing of packets
                       Enables devices that are not physically attached to
                        communicate
                       Examples of protocols IP and IPX,

Data Link              Combines packets into bytes and bytes into frames(
                        framing)
                       Provides access to media using MAC addresses, ensuring
                        messages are delivered to the proper device
                       Performs error detection not correction
                       Examples of standards Logical Link Control(LLC) 802.2
                       Media Access Control (MAC) 802.3




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Physical                 Moves bits between devices (physical topology)
                         Mechanical aspects include cabling, connectors necessary
                          to connect equipment to media
                         Electrical specifications such as voltages, impedance, wire
                          speed, pin out of cables and functional requirements for
                          ]activating, maintaining and deactivating a physical link
                          between end systems.
                         Specifies the media, copper wires, optical fibre, radio waves
                          and copper.
                         Standards used , Ethernet, Carrier Sense Multiple Access
                          with Collision Detection (CSMA/CD)
                         WiFi, Orthogonal Frequency-Division Multiplexing (OFDM),

Data transmission has evolved from very low speeds such as Telegraphy
through to ATM


2.13   Transmitting data via the Internet

2.14.1 Transmission Control Protocol

TCP is typically used by applications that require guaranteed delivery. It is a
connection –orientated protocol, which is responsible for verifying the correct
delivery of data from client to server. Data can be lost in the intermediate
network. TCP adds support to detect errors or lost data and to trigger
retransmission until the data is correctly and completely received.

TCP provides connections that need to be established before sending data. TCP
connections have three phases:
   1. connection establishment
   2. data transfer
   3. connection termination

TCP establishes a full duplex virtual connection between two endpoints. Each
endpoint is defined by an IP(internet protocol) address and a TCP port number
and is implemented as a finite state machine.

The data being sent (the ―byte stream‖) is transferred in segments. The window
size determines the amount of data (number of bytes) that can be sent before an
acknowledgement from the receiver is necessary.

On the contrary User Datagram Protocol UDP can immediately start sending
―packets‖ of data via the internet without guaranteeing the delivery of the packets
.It is a connectionless protocol. The two most typical network applications that

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use TCP are File Transfer Protocol (FTP) and the TELNET.

FTP is an application that allows data files to be transferred between devices.
Telnet is an application that allows remote access into device.

Example
FTP is used with Wildtrack, Footprint Identification Technique. A digital camera is
used to capture images of footprints, and these are downloaded onto a laptop,
and optimised with photo software. With Internet access one transfers the image
(using FTP) to a remote database or management system that compares the
image with what is in the archives. A confirmation of the species is then
generated. This technique is used to monitor and analyse information on
endangered species. For efficiency over fast networks with short latency, UDP
might be best for example the need for credit card verification processes when
paying subscriptions for a service like Bushmail.

TCP is best suited where efficiency over long-haul circuits is needed e.g. WAN,
the internet cloud. The internet gives voice to people and communities whose
natural resources are being threatened. It is a powerful tool that brings together
multicultural organisations and communities to share experiences on
conservation and development projects regardless of geographical differences.

2.14.2 Internet Protocol (IP)
Whilst TCP manages the packets that data is divided up into when it is sent, IP is
responsible for forwarding packets of data to the right location and for their
delivery. IP forwards each packet based on a four-byte destination address (the
IP number). The Internet authorities (AFRINIC, RIPE) assign ranges of numbers
to different organizations. The organizations assign groups of their numbers to
departments. IP operates on gateway machines that move data from department
to organization to region and then around the world.




2.15   Bushmail

Bushmail is an email facility that uses HF radio powered by a 12 volt battery with
an antenna suspended from a tree.




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Figure 7: Bushmail Connection
Source: http://www.bushmail.net

Features

      Allows 100K Excel and Word documents to be sent.
      Voice communications is supported but it is not secure.
      Cheap, flat annual rate is charged regardless of usage.
      Sending of free email SMS messages but no internet browsing.
      Does not allow spam and through its filters.
      Slow, email message delivery is slow due to low baud speeds supported
       of 2000 to 6000.
      It is robust and runs in remote areas.
      Has unlimited text email from very remote areas. Used in many reserves
       including Kruger National Park, some areas in Zimbabwe like Zambezi
       Valley, Botswana, Zambia, Tanzania, and Mozambique.
      Coverage is in Africa only.
      Easy to install, (DIY)




Session 3: Tools for Communication
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3.1       Learning Objective: Summarise the use of the communication tools

Framework:

         List the communication tools
         List their applications
         How can these tools be used in relevance to the conservation and
          development?

3.2       Content
Table 4: Use of Communication Tools

                                    Fixed or                                          Carrier
  Tool              Service/s                     Uses of the service
                                    portable?                                         technology
                                                  Direct communication, i.e. to
                                                                                       GSM     network
                    Voice                         local   communities    within
                                                                                      (voice channel)
                                                  range, with HQ.
                    data        –                 as above                             GSM network
                    SMS
                                                  instant transfer of images
  Mobile            data     -
                                    portable      captured in the field (i.e., to     MMS via          GSM
  phone             Digital
                                                  report    illegal poaching    /     network
                    pictures
                                                  activate response)

                    data        –                 relatively inexpensive field
                                                                                      GPRS or 3G (via
                    email                         based     communication   for
                                                                                      GSM    or   3G
                                                  long-distance / international
                                                                                      network)
                                                  correspondence
                    Voice                         (Voice)    communication in
                    data        –                 extremely remote places or
                    SMS                                                               Satellite
                                                  others not served by GSM or
  Satellite                                       landline infrastructure
                                    portable
  phones
                    data        –                 (Data) (ditto)                      Satellite
                    email                                                             BGAN         unit/
                                                  (Data) (ditto)
                                                                                      satellite
                    Voice                         Low-cost                voice
                                                                                      Air!
  UHF / VHF                                       communication over distance
                                    portable
  radio             Bushmail                      Entry-level email functionality
                                                                                      Air!
                                                  over distance
                                    portable      Voice communication between
  Shortwave
                    Voice           (within ~     individuals or small teams in       Air!
  radio
                                    5 km)         shorter range
                                                                                      PSTN     (public
                    Voice           fixed         Voice communication
                                                                                      network)
  Landline                                        Web browsing, sending SMS
  phone             Internet/
                                    fixed         via web, email, chat, Skype         PSTN
                    email
                                                  etc.
                     Fax            fixed         Sending documents                   PSTN

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3.3   Relevance of Communication Technologies

The presence of communication technologies has greatly improved information
flow especially in areas that are remote and infrastructure for more traditional
modes of communication is not in place. The following examples illustrate some
of the potential applications of telecommunications for conservation and
sustainable development purposes – and the impacts they can generate:
      To improve access to markets farmers are now using mobile handsets to
       locate the best prices for their produce, by contacting the buyers before
       travelling with the orders. This dramatically increases cost-efficiency as
       deliveries can be made to the most lucrative buyer.
      Assisting the process of accessing markets can also promote community-
       based natural resource management (CBNRM) by helping small business
       enterprises in the marketing and selling of sustainable produced products.
      To improve sharing of, and access to, information that informs better
       management of conservation areas and better use of natural resources.
       Sharing lessons learnt or the latest best practice, or communicating
       emergency issues that require rapid response.
      To raise community awareness of local conservation issues, for example,
       community-based websites can increase knowledge and information on
       conservation issues (local and national), and help promote protection of
       the local environment.
      Mobile news services, broadcast on SMS keeps can keep community
       stakeholders informed on the latest events, topical competitions &
       emergency alerts in a very inexpensive way. Supposing there is an
       outbreak of a disease, fire, poaching or animals straying away, ICTS
       improve the speed, effectiveness and quality of response to such threats.
      Opening news lines of communication between protected area authorities
       and local communities (via SMS, for example) can go a long way towards
       improving relationships and easing tensions.
      Targeted use of ICTs could allow for more effective law enforcement by
       improving in administrative and communications capacity, which in turn
       help to improve environment and wildlife protective measures.
      ICTs could enable a proactive, speedier and standardised
       communications platform for protected area management, resulting in
       improved environmental planning management and monitoring.
      To enhance data management by providing a new way of recording,
       sharing, distributing and analysing data (e.g. on elephant populations,
       wildlife tracking, using Footprint Identification Techniques).
      Improving external communications by connecting conservation areas to
       the outside world, e.g. to headquarters of NGOs, and even overseas. It
       brings together multicultural organisations and communities to share
       experiences regardless of the geographical differences.
      To supports eco-tourism, effective communications are essential to
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          access tourism markets and encourage increased visitors to conservation
          areas
         To Study of wildlife migration patterns by using GPS Remote Release
          Collar for Wildlife tracking and tracking. Frequency of wildlife tracking
          collars range from 215 – 220Mhz
To stay in touch with colleagues / local partners when in remote
locations        lacking        extensive        communications
infrastructureSession 4: Practical

4.1       Learning Objective: Attain the skill of using a data and a voice application

Framework:
    Demonstrate the use of bulk SMS messaging technology platforms. Web
     based SMSMalls and stand alone application of FrontlineSMS

4.2   Practical A
Aim: Demonstrate the use of FrontlineSMS

Demonstrate the following
   Create and manage all of your SMS-related contact groups
   Send and receive messages via special on-screen consoles
   Engage with your contact groups - run surveys, competitions etc. via the
     Survey Manager
   Run your own text-based information service via the automated Reply
     Manager

NB* FrontlineSMS messaging solution was developed for the non profit sector
   Handles flash messages and long messages up to 320 characters in
      length
   Provides incoming and outgoing message history for each contact
   There is no need to be on-line it works on any GSM network via your own
      PC or laptop
   Your data is all held locally, and not on a centralised on-line server.
   When running on a laptop the system continues to work during power
      outages
   The system will allow incoming text messages - not all web-based
      systems are able to do this simply and easily. Two-way communication is
      a vital function for full field communications or to carry out surveys
   With this two-way portable communications capability, field-based NGOs
      can keep in touch with their fieldworkers from anywhere in the field. This
      provides valuable contact during operations, or for monitoring movements
      of poachers, wildlife etc.


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Bibliography and Websites

http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html
        The Electromagnetic Spectrum

http://en.wikipedia.org/wiki/Electromagnetic_spectrum
        The Electromagnetic Spectrum

http://en.wikipedia.org/wiki/Fresnel_zone
        Fresnel Zone

http://www.howstuffworks.com/wireless-network
        WiFi

http://frontlinesms.kiwanja.net
         FrontlineSMS

http://www.kiwanja.net
        Application of ICTs

http://www.bushmail.net
        Bushmail

http://www.awt.co.za
        Tracking devices

http://www.masabi.com/scFFI.html
        Gaming applications

http://www.t4cd.org
        t4cd website & technology database

Rob Flickenger                   Wireless ebook
                                 Propagation of Radio Waves

Sebastian Bluettrich             Basic Radio physics HANDOUT,
                                 wireless.dk


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T4CD Resource Disk                 Communication Technologies


Wiley                              GSM Basics, Fundamentals of Telecommunications.
                                   2nd.Edition.Apr.2005

OSI layer Sybex Cisco Certified 640-801 Study Guide 5th Edition




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