Report on Industrial Visit to Mtnl

REPORT ON INDUSTRIAL VISIT TO MTNL

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Date: 7 September 2011 Place: Mumbai An industrial visit was organized for the final students of Electronics & Telecommunication by our college - Raijv Gandhi Institute Of Technology. The venue was MTNL (Mahanagar Telephone Nigam Ltd.) - India's most reputed telecom company located at MIDC, Marol, Mumbai. The goal of the industrial visit was to achieve better understanding and practical exposure of Mobile Communications Communications Systems. Mahanagar Telephone Nigam Limited (MTNL) is a state-owned telecommunications service provider in the metro cities of Mumbai and New Delhi in India. MTNL provides fixed line telephones, cellular connection of both GSM — Dolphin(Postpaid) and Trump (prepaid) and CDMA — Garuda-FW  And Garuda-Mobile and internet services through dialup and Broadband internet TriBand . MTNL has also started Games on demand, video on demand and IPTV services in India through its Broadband Internet service called Triband. Former Indian Communications Minister - Thiru Dayanidhi Maran had declared year 2007 as "Year of Broadband" in India and MTNL is gearing up to provide five million Broadband connectivity by the end of 2007. MTNL started 3G services in India under the name of "MTNL 3G Jadoo" Services offered include Video call, Mobile TV and Mobile Bro adband with high speed data connectivity up to 3.6 Mbit/s speed from 11 December 2008, getting India on the 3G map of the world. MTNL plans to offer 3G services across India by mid-2009. After that MTNL Mobile users would be able to surf  the internet with speeds up to 3.6 Mbit/s on their smart phones. MTNL also provides data cards for surfing internet on the PC and Laptop at 3.6 Mbps. MTNL will be installing 15 lakh 3G lines in the first phase of its 3G roll-out in Mumbai and Delhi (which currently have 40 lakh existing mobile lines).MTNL rolled out its BlackBerry solutions on the 2G and 3G networks by launching India’s first 3G enabled BlackBerry Bold smart phones.

We were scheduled to assemble in the bus by 12:30 pm. Fighting our way through the heavy traffic we finally reached our destination around 1:30 pm. We were accompanied and guided by our professors namely Prof.S.D.Patil Sir, Prof.Kulkarni Sir and Prof.Boyer Sir. We were split into three groups with a Professor heading each group. Each group visited the following three sites which form the main part of any telephone exchange: 1. Antenna site. 2. Base Transreceiver station(BTS). 3. Base Station Controller(BSC).

First, our group was taken to the BSC (Base Station Subsystem) centre. The equipments were manufactured by Motorola. Mr.Shinde explained us the architecture and working of the GSM system. The GSM mobile station (or mobile phone) communicates with other parts of the system through the base station system. The base transceiver station (BTS) handles the radio interface to the mobile station. The base transceiver station is the radio equipment (transceivers and antennas).

The BSC provides the control functions and physical links between the MSC and BTS. It provides functions such as handover, cell configuration data and control of RF power levels in base transceiver stations. A number of BSCs are served by a MSC. He then explained us the concept of duplexers which allows bi-directional communication over a single channel.

We also got the opportunity to practically observe the alarm conditions of BSC when Mr.Shinde disengaged the cooling system that resulted in a warning. He was extremely generous to answers our silliest questions with great enthusiasm. He explained that the main reasons for network blockage during festivals and disasters were to prevent system overload thus busting all the previous myths we believed. Our group was then taken up to the terrace to have a breathtaking view of the city and observe the various antennas used at MTNL. The Antennas were mounted on the top of the MTNL building. A metal rod or dish was used to transmit as well as receive signal. The antenna used a module that consisted of  a transmitter to transmit the voice electrical signals into the free space in the form of RF signal and the receiver to receive the RF signal from the space. In order to increase the system capacity and reduce the co-channel interference three unidirectional antennas were installed on the top with each operating in 120 degree sector and the sectored are named as the Alpha(α), Beta(β) and Gamma(γ).

Our group was then taken to the Main Switching Centre. The head of the Control department  – ‘S. K. Yadav’, explained us about how switching takes place and how the antennas are designed. First he started explaining the concept of Line Of Sight (LOS). Line Of Sight (LOC) should be maintained between the two BTS and if there is a building coming up between the two BTS then the BTS should be aligned again properly in order to obtain proper LOS. These switching equipments are monitored by a server which takes care of all the modulation and demodulation operation. Each switching centre has 8 transceiver system so total 64 transmitter and receiver in a given location or area in provided. For one BTS there is a 4Mb of link provided. The transmission is done using the PWM pulses and then passed to the BTS antenna and then the signal is transmitted. The switching equipments were of ‘Siemens’ and ‘Himachal Electronics Ltd.’

The visit was concluded by thanking the MTNL department for allowing us to experience and observe such cutting edge technology. It surely improved our understanding of Mobile Communications systems and widened our scope of  thinking. Such visits should also be initiated for other subjects to help us get a better understanding of practical systems. It was a wonderful experience which will be always remembered and cherished by one and all.

By:Siddharth Agarwal B.E EXTC Roll No - 701