Internship Report on Telecommunication in Bangladesh

Telecommunication links via satellites are bringing about revolutionary changes in the Fields of communication. The barriers of spaces and time have totally collapsed. Not very long ago it took days to the communicate to someone through a letter but the new STD and ISD facilities have made communication an instantaneous process. The world appears to have contracted or been squeezed into a small room in which, given certain facilities, it is possible to communicate with anyone in any part in the world.
GSM: GSM stands for "Global System for Mobile Communications." GSM is mostly a European system and is largely unused in the US. GSM is interesting in that it uses a modified and far more efficient version of TDMA. GSM keeps the idea of timeslots and frequency channels, but corrects several major shortcomings. Since the GSM timeslots are smaller than TDMA, they hold less data but allow for data rates starting at 300 bits per second. Thus, a call can use as many timeslots as necessary up to a limit of 13 kilobits per second. When a call is inactive (silence) or may be compressed more, fewer timeslots are used. To facilitate filling in gaps left by unused timeslots, calls do "frequency hopping" in GSM. This means that calls will jump between channels and timeslots to maximize the system’s usage. A control channel is used to communicate the frequency hopping and other information between the cell tower and the phone. To compare with the other systems, it should be noted that GSM requires 1 Watt of output power from the phone.

CDMA: CDMA stands for "Code Division Multiple Access" and is both the most interesting and the hardest to implement multiplexing method. CDMA has been likened to a party: When everyone talks at once, no one can be understood, however, if everyone speaks a different language, then they can be understood. CDMA systems have no channels, but instead encode each call as a coded sequence across the entire frequency spectrum. Each conversation is modulated, in the digital domain, with a unique code (called a pseudo-noise code) that makes it distinguishable from the other calls in the frequency spectrum. Using a correlation calculation and the code the call was encoded with, the digital audio signal can be extracted from the other signals being broadcast by other phones on the network. From the perspective of one call, upon extracting the signal, everything else appears to be low-level noise. As long as there is sufficient separation between the codes (said to be mutually orthogonal), the noise level will be low enough to recover the digital signal. Each signal is not, in fact, spread across the whole spectrum (12.5 MHz for traditional cellular or 60 MHz in PCS cellular), but is spread across 1.25 MHz "pass-bands." CDMA systems are the latest technology on the market and are already eclipsing TDMA in terms of cost and call quality. Since CDMA offers far greater capacity and variable data rates depending on the audio activity, many more users can be fit into a given frequency spectrum and higher audio quality can be provide. The current CDMA systems boast at least three times the capacity of TDMA and GSM systems. The fact that CDMA shares frequencies with neighboring cell towers allows for easier installation of extra capacity, since extra capacity can be achieved by simply adding extra cell sites and shrinking power levels of nearby sites. CDMA technology also allows lower cell phone power levels (200 miliwatts) since the modulation techniques expect to deal with noise and are well suited to weaker signals. The downside to CDMA is the complexity of deciphering and extracting the received signals, especially if there are multiple signal paths (reflections) between the phone and the cell tower (called multi path interference). As a result, CDMA phones are twice as expensive as TDMA phones and CDMA cell site equipment is 3-4 times the price of TDMA equivalents.

Advantages of GSM:
· GSM is already used worldwide with over 450 million subscribers.
· International roaming permits subscribers to use one phone throughout Western Europe. .
· GSM is mature, having started in the mid-80s. This maturity means a more stable network with robust features. CDMA is still building its network.
· GSM's maturity means engineers cut their teeth on the technology, creating an unconscious preference.
· The availability of Subscriber Identity Modules, which are smart cards that provide secure data encryption give GSM m-commerce advantages.

Disadvantages of GSM:
· Lack of access to burgeoning American market.

Advantages of CDMA include:
· Increased cellular communications security.
· Simultaneous conversations, less call drops, strong network.
· Low power requirements and little cell-to-cell coordination needed by operators.
· Extended reach - beneficial to rural users situated far from cells.

Disadvantages of CDMA include:
· Due to its proprietary nature, all of CDMA's flaws are not known to the engineering community for solving.
· CDMA is relatively new, and the network is not as mature as GSM.
· CDMA cannot offer international roaming, a large GSM advantage.

Back ground of Grameen Phone
GrameenPhone has just completed its eighth year of operation. The GP network went on-air on March 26, 1997 and it has grown from strength to strength since then.
GP now has the largest network with the widest coverage around the country. And plans are underway to further increase the coverage to 80 per cent of the population within this year, from the current 55 percent.
The company has become one of the largest private sector investments and also the largest single tax payer in the country. It may be mentioned here that the shareholders of GrameenPhone have re-invested most of the earnings so far, enabling the company to continuously increase the capacity and expand the coverage area of its network.
November 28, 1996: Grameen Phone was offered a cellular license in Bangladesh by the Ministry of Posts and Telecommunications
March 26, 1997: Grameen Phone launched its service on the Independence Day of Bangladesh
After eight years of operation, Grameen Phone has more than 2.8 million subscribers as of March 2005.