MOBILE

COMMUNICATION

PRESENTED BY:- SOURABH KANT

ANALOG communicatio

n

1G Frequency Division Multiple Access (FDMA)

DIGITAL communication

2G, 3g, 4g… Time Division Multiple Access (TDMA) & Code Division Multiple Access (CDMA)

TYPES OF MOBILE COMMUNICATION

Communication is done wirelessly by using FDMA technique between Base Stations(BS) & Mobile Stations(MS).

It only supports voice communication. Although 1G & 2G systems uses digital signaling to

connect the radio towers (Base Stations) to the rest of the telephone system, the voice during a call is encoded to digital signals (TDM & CDM) in 2G, whereas voice in 1G is only modulated to higher frequency (i.e. FM), typically at 150 MHz and up.

1G speeds vary between 28k modem(28kbit/s) and 56k modem(56kbit/s).

Example : AMPS (Advanced Mobile Phone System) used in the North America and Australia.

Analog cellular networks

uses separate frequencies, or "channels", for each conversation (FDMA). It therefore required large bandwidth for a large number of users.

the Base station could flexibly assign channels to handsets based on signal strength, allowing the same frequency to be re-used in various locations without interference. This allows a larger number of phones to be supported over a geographical area.

Disadvantage (compared to Digital systems): 1. very sensitive to noise and static. 2. no protection against call theft.3. Only supports voice communication

Advanced Mobile Phone System (AMPS )

Communication is done wirelessly by using TDMA or CDMA technique between Base Stations(BS) & Mobile Stations(MS). Thus, digital systems are significantly more efficient on the spectrum, allowing for far greater mobile phone penetration levels.

It supports voice, data, and multimedia communication. Thus, data processing became possible and SMS, MMS, Internet Access, VoIP, Fax, etc. existed.

Digital voice data can be compressed and multiplexed much more effectively than analog voice encodings. Thus, Less power used by BS and MS, and small & cheap BS /MS equipments existed.

After 2G, newer technologies 2.5G, 2.75G, 3G, 4G, etc. are now launched which has increased the speed of data transfer from 56 kbit/s up to 115 kbit/s and more, as the need for speed is increasing day by day.

Digital Cellular network

2G technologies can be divided into TDMA-based and CDMA-based standards depending on the type of multiplexing used. The main 2G standards are:

1. GSM (TDMA-based), originally from Europe but used in almost all countries.

2. Over 60 GSM operators are also using CDMA2000 in the 450 MHz frequency band (CDMA450).

3. IS-95 or CDMA-One (CDMA-based, commonly referred as simply CDMA in the US), used in the Americas and parts of Asia.

4. GPRS (General Packet Radio Service), used for WAP, MMS, internet service. It is sometimes called 2.5G

5. EDGE (Enhanced GPRS) is also a GPRS with increased speed. It is sometimes called 2.75G

Types of 2G Technologies

Cellular Network Structure

GSM Infrastructure

Logical channels

Forward link is from BS to MS

Downward link is from MS to BS

There are two types of Logical channels: 1. control channels, and 2. traffic channels.

Control channels are less and are used for sending beacon signals, page signals, control information, SMS and orders. MS users share this channel.

Traffic channels are used for transmitting the voice signals at the time of conversation, and it is individually given to each MS user by BS

Frequency Reuse Pattern Same frequency band

used in a cell can be used by in another cell at far distance D from the cell of radius R.

This increases the efficiency available bandwidth.

Reuse Distance D=R√3N (N= no. of cells in a cluster)

Common hex cell clusters are of 1, 3, 4, 7, 9, 12, 13, 16 cells.

Cell Sectoring

Cell Sectoring by Directional Antennas

The Base transceiver station, or BTS, contains transceivers (the equipment for transmitting and receiving radio signals), antennas, and a tower.Directional BTS has more then one antennas on its tower which covers different sectors of cell areas. This is cell sectoring.This reduces the interference of the same frequency signals coming from adjacent BTS, in frequency reuse pattern.

Thank You