FINAL YEAR PROJECT ON:

At Cellular Pvt. Ltd., Mumbai.

Address:Windsor Plaza, Off CST Road,Kalina,Santacruz(East),Mumbai-98

An Aditya Birla Group Enterprise

Presented By:

AKSHAY PALKAR AVINASH NAIR NIRAV GUPTA ROHIT MATHUR

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Cell

Location Area

MSC/VLR Area

MSC

VLR

PLMN Service Area

HLR

MSCMSC

VLR

GSM AREA

GSM Network Hierarchy

PROJECT OBJECTIVES

To have a complete understanding about mobile telephony. To understand sequential execution of network planning and optimization. To have a complete exposure of practical steps followed in cell-site implantation. To get acquainted with network designing through the process of site survey and on-air site drive test.

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GSM Migration path•GSM: Primarily voice service with circuit switched data service ( SMS).•GPRS ( General Packet Radio Service): A step ahead to GSM, with basic Packet services up to 117 kbps throughput. Requires additional hardware to facilitate the packet service. Could be used for MMS, Data services of lower throughput requirement.•EDGE (Enhanced Data for GPRS Evolution): Enhanced (data) packet service with approximately 384 kbps throughput. Could be used for Video streaming, Online gaming, downloading multimedia contents with acceptable latencies and enhanced throughput.•UMTS-R99 ( Universal Mobile Telecommunication System): This was the advent of 3G services, beyond EDGE/GPRS ( 2.5 G) with capability of delivering approximately 2.14 mbps throughput.•HSPA ( High Speed Packet Access): An enhanced packet service over UMTS capable of providing a throughput of 14.4 Mbps and offers rich multimedia experience with Voice & Video call ( CS 64), high speed internet. It also offers: Video streaming, high speed internet, online gaming, VoD, Security etc. HSPA –> HSDPA + HSUPA

GSM GPRS EDGE UMTS HSPA

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One Cell in a City

One BTS Site Covering This Cell

( Cell is Divided inThree Sectors )

City Divided inVarious Cells

Concept of Cell in GSM Network

Difference between GSM 900 & GSM 1800

As we know that the higher the frequency, the smaller will be the Wavelength ( λ = C/ f ,where c is speed of light i.e. 3*108 & f is the operating frequency ).Therefore the propagation distance traveled by the Signal in GSM 1800 will always be less as compared to that in GSM 900.Hence, for similar propagation conditions and clutter scenario the losses ( Propagation losses & Building penetration losses) experienced in GSM 1800 will be more than in GSM 900.

Due to this reason the number of sites planned to cover similar Area will be more in GSM 1800 as compared to the number of sites in GSM 900.

Also since antenna length is proportional to λ ( i.e. λ/4), therefore the antenna length in GSM 1800 will be different that in GSM 900.

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Transmission Problems

In radio communication the transmission quality varies from one place to another.

Two major factors affecting quality of transmission are: 1. Distance between transmitter and receiver2. Reflections or obstructions due to man made or natural structures

- General Transmission problems affecting Transmission Quality: Path Loss Shadowing Multi path Fading

INTERFERENCE PROBLEMS

For a GSM network due to limited spectrum bandwidth, interference of channels is unavoidable.

The two primary interference problems faced by a stand alone GSM network are:-

Co-channel interference: It is the ratio of the level of the received desired signal level to the level of the received undesired signal level. It is caused by frequency reuse in the cellular network.

Adjacent channel interference: Neighboring frequencies are adjacent (only separated by 200 kHz) some of the power in the adjacent frequency will ‘break through’ the receiver filter for frequency ‘f’ and cause interference.

Cell site Survey :

The RF engineer goes to the location where the cell-site has been proposed by the GSM service provider. He checks the access and feasibility of the site and performs the technical survey considering various factors like clutter consideration, microwave linking, altitude of the building, AMSL, latitude and longitude. Evaluating the above mentioned factors he proposes the antenna orientation and tilt.

Drive Test :

The Drive Test engineer checks the network in the vicinity of the cell-site with the help of specially designed software (TEMS in case of Idea), site map and GPS. The channel frequencies and hopping frequencies are properly allotted.

Optimization:

If channel interference occurs or low signal strength is detected during drive test, the antenna orientation and tilt is accordingly adjusted.

Thank You