1. NATIONAL COLLEGE OF SCIENCE AND TECHNOLOGY
Amafel Bldg. Aguinaldo Highway Dasmariñas City, Cavite
ASSIGNMENT 1
CELLULAR TECHNOLOGY
Olaño, Reymart M. October 03, 2011
Communications 1/ BSECE 41A1 Score:
Engr. Grace Ramones
Instructor

2. Cellular technology has changed the world. You can even successfully make the argument that
this technology is more important than the Internet itself because it enables us to take the Internet
anywhere. Since the invention of the Internet, the ability to take it anywhere has also changed
the world. The world has become one large mobile society. The significance of global
communications is such that we now know news instantaneously as it happens. Being mobile
enables all of us to be connected and makes the world seem like a much smaller place. How
does this technology work?
Cellular technology is actually a series of radio network served by a fixed location transceiver
and known as a cell site
.
When these cells are connected together, they provide what we know as radio coverage over a
large geographic area. While knowing how this technology works is interesting (or not), the
significance of it is how it affects and impacts our daily lives. Our lives are impacted in some of
the following ways: texts, phone calls, videos, Internet, GPS, entertainment, learning, knowledge
and all of these falls under the broader heading of communications. How we communicate and
what we communicate is what has changed our lives as we know it. For the person who is 45
years old and older, you have probably lived through all of these changes and understand that the
world is progressively, substantially different that when you were a kid. For those reading this
that is 20 or younger, the world most definitely was not always this way.
The first major impact of this technology is the inexpensive availability of this technology to
everyone in the form of cell phones. Ownership of cellular devices range from the idle rich who
have latest version of whatever new gimmick is on the market and costs a small fortune to a
homeless individual with lower than low or non-existent credit scores. The point is that anyone
can own a cellular device. If you are homeless, you will obviously not be able to afford the
make and model the rich own. However, you can still own the cheapest device out there and be
part of the mobile society.

3. Cellular Technology: The Impact on Modern Day Life
One of the impacts of this relatively new technology is that an entire generation has
communicated through texting, the typing and sending of brief messages over their cell phones.
A new type of abbreviated language has even been created to keep the labor of this
communication brief.
The most logical question about texting comes from the older generation and goes like this: why
don’t you just call the person instead of sending them a message? Phone calls are not always
convenient. Some of the places where a phone call might cause a major interruption or
distraction would be in a meeting at work, in a classroom setting, in a church service or in the
movies. However, a text is quiet and simple and gets the message across to the recipient. Young
people texts like older people breathe.
The older people still primarily communicate through phone calls. However, the major
advantage of cell phones is that you are now freed up to eliminate your land line because you
really don’t need both of them. With their cell phone they can now call anyone from anywhere.
They are on the go like never before and their calls go with them.
Another wonder of cellular technology is the ability to watch videos on your cell phone. Videos
first gained prominence in the very early 1980s with the advent of MTV. The earliest videos
were music videos, but since have evolved into everything from home movies, major studio
motion picture releases and television programs. Probably the largest carrier of videos in a
vehicle called You Tube. This vehicle is a web site that is accessed through the Internet. Thanks
to the ability to communicate through cell phones, we as a society are able to carry our videos
with us to amuse, entertain or inform.
Arguably, the most significant aspect of cellular technology is the ability to carry the Internet
with us to any location where cell coverage is available and in the United States, that is a
majority of the country with the exception of some rural areas. Think of the Internet as your own

4. pack and carry version of the most sophisticated public library that you have ever visited. The
Internet allows you to find practically anything that is out there in the form of knowledge. The
Internet facilitates most learning about any topic known to man. Colleges and universities offer
classes over the Internet. You do not even need to step into a classroom to get certain degrees.
A mobile Internet, enabled by cellular technology, is arguably the greatest invention of the last
fifty years.
The Major Advantages of Cellular Technology
Apps for mobile phones is one of the major advantages to being mobile and on the go, especially
to places we are unfamiliar with, is what is known as the GPS, or global positioning system.
Some of the more sophisticated cellular devices come with a GPS option, so you can always find
your way. Today’s GPS is like road maps used to be without all the clutter and information that
you don’t need.
Cellular technology is entertaining. Though you can tell a joke through texting or live during a
phone call, the other possibilities are endless: music, music videos, movies, photographs, video
games, word games and television programs are just a few of the ways that you can keep
yourself entertained. They key to this technology is how long your batter life is and keeping
your cellular device charged.
None of this would have been possible without cellular technology, which is practically
synonymous with being on the move. Being on the move is total freedom, not being tied to a
specific location for anything. In the past, vocations and careers stated that we sometimes had to
stay in one location and for some, that is still the case. But most of us can work, be entertained
and socialize from the road thanks to cellular devices.

5. History
Radiophones have a long and varied history going back to Reginald Fessenden's invention and
shore-to-ship demonstration of radio telephony, through the Second World War with military use
of radio telephony links and civil services in the 1950s.
The first mobile telephone call made from a car occurred in St. Louis, Missouri, USA on June
17, 1946, using the Bell System's Mobile Telephone Service. The equipment weighed 80 pounds
(36 kg), and the AT&T service, basically a massive party line, cost US$30 per month (equal to
$337.33 today) plus 30–40 cents per local call, equal to $3.37 to $4.5 today.
In 1956, the world’s first partly automatic car phone system, Mobile System A (MTA), was
launched in Sweden. MTA phones were composed of vacuum tubes and relays, and had a weight
of 40 kg. In 1962, a more modern version called Mobile System B (MTB) was launched, which
was a push-button telephone, and which used transistors to enhance the telephone’s calling
capacity and improve its operational reliability, thereby reducing the weight of the apparatus to
10 kg. In 1971, the MTD version was launched, opening for several different brands of
equipment and gaining commercial success.
Martin Cooper, a Motorola researcher and executive is considered to be the inventor of the first
practical mobile phone for handheld use in a non-vehicle setting, after a long race against Bell
Labs for the first portable mobile phone. Using a modern, if somewhat heavy portable handset,
Cooper made the first call on a handheld mobile phone on April 3, 1973 to his rival, Dr. Joel S.
Engel of Bell Labs.
The first commercially automated cellular network (the 1G) was launched in Japan by NTT in
1979, initially in the metropolitan area of Tokyo. Within five years, the NTT network had been
expanded to cover the whole population of Japan and became the first nationwide 1G network. In
1981, this was followed by the simultaneous launch of the Nordic Mobile Telephone (NMT)
system in Denmark, Finland, Norway and Sweden. NMT was the first mobile phone network
featuring international roaming. The first 1G network launched in the USA was Chicago-based
Ameritech in 1983 using the Motorola DynaTAC mobile phone. Several countries then followed
in the early-to-mid 1980s including the UK, Mexico and Canada.
The first "modern" network technology on digital 2G (second generation) cellular technology
was launched by Radiolinja (now part of Elisa Group) in 1991 in Finland on the GSM standard,
which also marked the introduction of competition in mobile telecoms when Radiolinja
challenged incumbent Telecom Finland (now part of TeliaSonera) who ran a 1G NMT network.
In 2001, the launch of 3G (Third Generation) was again in Japan by NTT DoCoMo on the
WCDMA standard.[

6. MULTIPLE ACCESS
Frequency reuse
The increased capacity in a cellular network, comparing to a network with a single transmitter,
comes from the fact that the same radio frequency can be reused in a different area for a
completely different transmission. If there is a single plain transmitter, only one transmission
can be used on any given frequency. Unfortunately, there is inevitably some level of
interference from the signal from the other cells which use the same frequency. This means that,
in a standard FDMA system, there must be at least a one cell gap between cells which reuse the
same frequency.
The frequency reuse factor is the rate at which the same frequency can be used in the network. It
is 1/n where n is the number of cells which cannot use a frequency for transmission.
Code division multiple access based systems use a wider frequency band to achieve the same
rate of transmission as FDMA, but this is compensated for by the ability to use a frequency
reuse factor of 1. In other words, every cell uses the same frequency and the different systems
are separated by codes rather than frequencies.
Depending on the size of the city, a taxi system may not have any frequency reuse in its own
city, but certainly in other nearby cities, the same frequency can be used. In a big city, on the
other hand, frequency reuse could certainly be in use.
Frequency Division Multiple Access or FDMA is a channel access method used in multiple-
access protocols as a channelization protocol. FDMA gives users an individual allocation of one
or several frequency bands, or channels. It is particularly commonplace in satellite
communication. FDMA, like other Multiple Access systems, coordinates access between
multiple users. Alternatives include TDMA, CDMA, or SDMA. These protocols are utilized
differently, at different levels of the theoreticalOSI model.
Disadvantage: Crosstalk may cause interference among frequencies and disrupt the transmission.
FREQUENCY DIVISION MULTIPLE ACCESS
FDMA is distinct from frequency division duplexing (FDD). While FDMA allows multiple users
simultaneous access to a transmission system, FDD refers to how the radio channel is shared
between the uplink and downlink (for instance, the traffic going back and forth between a
mobile-phone and a mobile phone base station). Frequency-division multiplexing (FDM) is also
distinct from FDMA. FDM is a physical layer technique that combines and transmits low-
bandwidth channels through a high-bandwidth channel. FDMA, on the other hand, is an access
method in the data link layer.
FDMA also supports demand assignment in addition to fixed assignment. Demand
assignment allows all users apparently continuous access of the radio spectrum by assigning
carrier frequencies on a temporary basis using a statistical assignment process. The first
FDMA demand-assignment system for satellite was developed byCOMSAT for use on
the Intelsat series IVA and V satellites.
There are two main techniques:

7.  Multi-channel per-carrier (MCPC)
 Single-channel per-carrier (SCPC)
Time division multiple access (TDMA) is a channel access method for shared medium
networks. It allows several users to share the same frequency channel by dividing the signal into
different time slots. The users transmit in rapid succession, one after the other, each using its
own time slot. This allows multiple stations to share the same transmission medium (e.g. radio
frequency channel) while using only a part of its channel capacity. TDMA is used in the
digital 2G cellular systems such as Global System for Mobile Communications (GSM), IS-
136, Personal Digital Cellular (PDC) and iDEN, and in the Digital Enhanced Cordless
Telecommunications (DECT) standard for portable phones. It is also used extensively
in satellite systems, combat-net radio systems, and PON networks for upstream traffic from
premises to the operator. For usage of Dynamic TDMA packet mode communication.
TDMA is a type of Time-division multiplexing, with the special point that instead of having
one transmitter connected to one receiver, there are multiple transmitters. In the case of
the uplink from a mobile phone to abase station this becomes particularly difficult because the
mobile phone can move around and vary the timing advance required to make its transmission
match the gap in transmission from its peers.
TDMA in 2G systems
Most 2G cellular systems, with the notable exception of IS-95, are based on TDMA. GSM, D-
AMPS, PDC, iDEN, and PHS are examples of TDMA cellular systems. GSM combines TDMA
with Frequency Hopping and wideband transmission to minimize common types of interference.
In the GSM system, the synchronization of the mobile phones is achieved by sending timing
advance commands from the base station which instructs the mobile phone to transmit earlier
and by how much. This compensates for the propagation delay resulting from the light speed
velocity of radio waves. The mobile phone is not allowed to transmit for its entire time slot, but
there is a guard interval at the end of each time slot. As the transmission moves into the guard
period, the mobile network adjusts the timing advance to synchronize the transmission.
Initial synchronization of a phone requires even more care. Before a mobile transmits there is no
way to actually know the offset required. For this reason, an entire time slot has to be dedicated
to mobiles attempting to contact the network (known as the RACH in GSM). The mobile
attempts to broadcast at the beginning of the time slot, as received from the network. If the
mobile is located next to the base station, there will be no time delay and this will succeed. If,
however, the mobile phone is at just less than 35 km from the base station, the time delay will
mean the mobile's broadcast arrives at the very end of the time slot. In that case, the mobile will
be instructed to broadcast its messages starting nearly a whole time slot earlier than would be
expected otherwise. Finally, if the mobile is beyond the 35 km cell range in GSM, then the
RACH will arrive in a neighbouring time slot and be ignored. It is this feature, rather than
limitations of power, that limits the range of a GSM cell to 35 km when no special extension
techniques are used. By changing the synchronization between the uplink and downlink at the
base station, however, this limitation can be overcome.

8. 3G systems
Although most major 3G systems are primarily based upon CDMA[citation needed], time division
duplexing (TDD), packet scheduling (dynamic TDMA) and packet oriented multiple access
schemes are available in 3G form, combined with CDMA to take advantage of the benefits of
both technologies.
While the most popular form of the UMTS 3G system uses CDMA and frequency division
duplexing (FDD) instead of TDMA, TDMA is combined with CDMA and Time Division
Duplexing in two standard UMTS UTRA
Code division multiple access (CDMA) is a channel access method used by various radio
communication technologies. It should not be confused with the mobile phone
standards called cdmaOne, CDMA2000 (the 3G evolution of cdmaOne) and WCDMA (the 3G
standard used by GSM carriers), which are often referred to as simply CDMA, and use CDMA as
an underlying channel access method.
One of the basic concepts in data communication is the idea of allowing several transmitters to
send information simultaneously over a single communication channel. This allows several users
to share a band of frequencies (see bandwidth). This concept is called multiple access. CDMA
employs spread-spectrum technology and a special coding scheme (where each transmitter is
assigned a code) to allow multiple users to be multiplexed over the same physical channel. By
contrast, time division multiple access (TDMA) divides access bytime, while frequency-division
multiple access (FDMA) divides it by frequency. CDMA is a form of spread-spectrum signalling,
since the modulated coded signal has a much higher data bandwidth than the data being
communicated.
An analogy to the problem of multiple access is a room (channel) in which people wish to talk to
each other simultaneously. To avoid confusion, people could take turns speaking (time division),
speak at different pitches (frequency division), or speak in different languages (code division).
CDMA is analogous to the last example where people speaking the same language can
understand each other, but other languages are perceived as noise and rejected. Similarly, in
radio CDMA, each group of users is given a shared code. Many codes occupy the same channel,
but only users associated with a particular code can communicate. The technology of code
division multiple access channels has long been known. In the USSR, the first work devoted to
this subject was published in 1935 by professor D.V. Aggeev in the "CDMA". It was shown that
through the use of linear methods, there are three types of signal separation: frequency, time and
compensatory. The technology of CDMA was used in 1957, when the young military radio
engineer Leonid Kupriyanovich in Moscow, made an experimental model of a wearable
automatic mobile phone, called LK-1 by him, with a base station. LK-1 has a weight of 3 kg, 20-
30 km operating distance, and 20-30 hours of battery life ("Nauka i zhizn", 8, 1957, p. 49,
"Yuniy technik", 7, 1957, p. 43-44). The base station, as described by the author, could serve
several customers. In 1958, Kupriyanovich made the new experimental "pocket" model of
mobile phone. This phone weighs 0,5 kg. To serve more customers, Kupriyanovich proposed the
device, named by him as correllator. ("Nauka i zhizn", 10, 1958, p.66, "Technika-molodezhi", 2,
1959, 18-19) In 1958, the USSR also started the development of the "Altay" national civil
mobile phone service for cars, based on the Soviet MRT-1327 standard. The main developers of
the Altay system were VNIIS (Voronezh Science Research Institute of Communications)and

9. GSPI (State Specialized Project Institute). In 1963 this service started in Moscow and in 1970
Altay service was used in 30 USSR cities.
Space-Division Multiple Access (SDMA) is a channel access method based on creating parallel
spatial pipes next to higher capacity pipes through spatial multiplexing and/or diversity, by
which it is able to offer superior performance in radio multiple access communication systems.
In traditional mobile cellular network systems, the base station has no information on the
position of the mobile units within the cell and radiates the signal in all directions within the cell
in order to provide radio coverage. This results in wasting power on transmissions when there are
no mobile units to reach, in addition to causing interference for adjacent cells using the same
frequency, so calledco-channel cells. Likewise, in reception, the antenna receives signals coming
from all directions including noise and interference signals. By using smart antenna technology
and differing spatial locations of mobile units within the cell, space-division multiple access
techniques offer attractive performance enhancements. The radiation pattern of the base station,
both in transmission and reception, is adapted to each user to obtain highest gain in the direction
of that user. This is often done using phased arraytechniques.
In GSM cellular networks, the base station is aware of the mobile phone's position by use of a
technique called "timing advance" (TA). The Base Transceiver Station (BTS) can determine how
distant the Mobile Station (MS) is by interpreting the reported TA. This information, along with
other parameters, can then be used to power down the BTS or MS, if a power control feature is
implemented in the network. The power control in either BTS or MS is implemented in most
modern networks, especially on the MS, as this ensures a better battery life for the MS and thus a
better user experience (in that the need to charge the battery becomes less frequent). This is why
it may actually be safer to have a BTS close to you as your MS will be powered down as much
as possible. For example, there is more power being transmitted from the MS than what you
would receive from the BTS even if you are 6 m away from a mast. However, this estimation
might not consider all the MS's that a particular BTS is supporting with EM radiation at any
given time.
Advanced Mobile Phone System (AMPS) was an analog mobile phone system standard
developed byBell Labs, and officially introduced in the Americas in 1983, Israel in 1986,
and Australia in 1987. It was the primary analog mobile phone system in North America (and
other locales) through the 1980s and into the 2000s. As of February 18, 2008, carriers in the
United States were no longer required to support AMPS and companies such as AT&T and
Verizon have discontinued this service permanently. AMPS was discontinued in Australia in
September 2000