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COMPANY PROFILE:
Communications is the Tata Group’s largest investment and the Group’s objective is to provide end-to-end telecommunications solutions for business and residential customers across the nation, and internationally. The Group’s communications activities are currently spread primarily over four companies—Tata Teleservices Limited (TTSL) and its associate Tata Teleservices (Maharashtra) Limited (TTML), Tata Communication (erstwhile VSNL) and Tata Sky. Together, these companies cover the full range of communications services, including:
• Telephony Services: Fixed and Mobile
• Media and Entertainment Services: Satellite TV
• Data Services: Leased Lines, Managed Data Networks, IP/MPLS VPN, Dial-up Internet, Wi-Fi and Broadband
• Value-Added Services: Mobile and Broadband Content/Applications, Calling Cards, Net Telephony and Managed Services
• Infrastructure Services: Submarine Cable Bandwidth, Terrestrial Fiber Network and Satellite Earth Stations and VSAT Connectivity
PROFILE:-
Tata Teleservices is part of the INR Rs. 2, 51,543 crore Tata group that has over 8o companies, over 3, 30,000 employees and more than 3.2 million shareholders. With a committed investment of INR36, 000 crore in telecom, the group has a formidable presence across the telecom value chain.
Tata Teleservices spearheads the group’s presence in the telecom sector. Incorporated in 1996, Tata teleservices was the first to launch CDMA mobile services in India with the Andhra Pradesh circle.
Beginning with its acquisition of Hughes Telecom(India) Limited in December 2002[now renamed Tata teleservices (Maharashtra) Limited ],which provide services in the Mumbai and rest of Maharashtra telecom circle, the company has swung into expansion mode and currently has a pan-India state of the art network.
INTRODUCTION OF CDMA
CDMA/WIRELESS COMMUNICATION
MULTIPLE ACCESS
Why there is requirement of multiple access schemes? The answer is that the international authority for frequency management has allocated 25 MHz band to the cellular telephony. As we know that today there are many cellular users and to provide service to all of them a large frequency band is required. But the band is limited to 25MHz. So different multiple access schemes are used. It means that multiple access scheme allow number of users to use the same band. The different multiple access schemes are mentioned below:
1. FDMA
2. TDMA
3. CDMA
1 FDMA :-
FDMA is the acronym of Frequency Division Multiple Access. FDMA divides radio channels into a range of radio frequencies and is used in the traditional analog cellular system. With FDMA, only one subscriber is assigned to a channel at a time. Other conversations can access this channel only after the subscriber's call has been terminated or after the original call is handed off to a different channel by the system. FDMA cellular standards include AMPS (Advanced Mobile Phone Service) and TACS (Total Access Communications System).