INTRODUCTION : Telecommunications is a fascinating, fast paced industry that influences every aspect of our daily life like normal voice phone calls, connectivity to the Internet, satellite communications, surfing the web, fax transmissions, video conferencing, high speed data communications, and cable TV. Early forms of telecommunication include smoke signals and drums, signal flags and lights. More modern uses were the telegraph, telephone and even data transmissions. In the current day scenario, there are lot of telecommunication technologies evolved and used by people all over the world. Wireless technologies like GSM, CDMA, TDMA, UMTS, GPRS and latest technology 3G growing at a fast pace promising high speed data communications. This session is an attempt to collect various resources related to telecom (mostly wireless) which are scattered over the web.
OBJECTIVES :
Discuss about Telecom Technologies
GSM
CDMA,
GPRS
3G technologies
VOIP and
IPTV.
GSM
The Global System for Mobile communications (GSM: originally from Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. Its ubiquity makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world. GSM differs significantly from its predecessors in that both signaling and speech channels are digital call quality, and so is considered a second generation (2G) mobile phone system. The key advantage of GSM systems to consumers has been higher digital voice quality and low cost alternatives to making calls, such as the Short message service (SMS, also called "text messaging"). The advantage for network operators has been the ease of deploying equipment from any vendors that implements the standard. Like other cellular standards, GSM allows network operators to offer roaming services so that subscribers can use their phones on GSM networks all over the world.
GSM is a cellular network, which means that mobile phones connect to it by searching for cells in the immediate vicinity. There are five different cell sizes in a GSM network-macro, micro, pico, femto and umbrella cells. The coverage area of each cell varies according to the implementation environment.
Macro cells can be regarded as cells where the base station antenna is installed on a mast or a building above average roof top level.
Micro cells are cells whose antenna height is under average roof top level; they are typically used in urban areas.
Picocells are small cells whose coverage diameter is a few dozen metres; they are mainly used indoors.
Femtocells are cells designed for use in residential or small business environments and connect to the service provider's network via a broadband internet connection.
Umbrella cells are used to cover shadowed regions of smaller cells and fill in gaps in coverage between those cells.
Cell horizontal radius varies depending on antenna height, antenna gain and propagation conditions from a couple of hundred meters to several tens of kilometres. There are also several implementations of the concept of an extended cell, where the cell radius could be double or even more, depending on the antenna system, the type of terrain and the timing advance.
Indoor coverage is also supported by GSM and may be achieved by using an indoor picocell base station, or an indoor repeater with distributed indoor antennas fed through power splitters, to deliver the radio signals from an antenna outdoors to the separate indoor distributed antenna system. These are typically deployed when a lot of call capacity is needed indoors; for example, in shopping centers or airports. However, this is not a prerequisite, since indoor coverage is also provided by in-building penetration of the radio signals from any nearby cell.
GSM networks operate in a number of different carrier frequency ranges (separated into GSM frequency ranges for 2G with most 2G GSM networks operating in the 900 MHz or 1800 MHz bands. Regardless of the frequency selected by an operator, it is divided into timeslots for individual phones to use. This allows eight full-rate or sixteen half-rate speech channels per radio frequency. These eight radio timeslots (or eight burst periods) are grouped into a TDMA frame. Half rate channels use alternate frames in the same timeslot. The channel data rate for all 8 channels is 270.833 kbit/s, and the frame duration is 4.615 ms.
CDMA
"CDMA" stands for Code Division Multiple Access, a pioneering voice transmission standard technology that was first used by the Allied forces during the World War-II. Basically, the CDMA technology has multiplexing transmission platform. It is an open air transmission that uses radio frequencies in order to offer connectivity, whether between mobile nodes or even between a mobile node and the traditional public switched telephone networks.
Much like data sent over the Internet, CDMA dismantles data when sent and then reassembles them upon arrival. The technology allows multiple calls to be carried over one channel. The technology facilitates earth stations which have unique identifying codes modulated with the communication signal, to transmit data at the same frequency at a time at low power level. It operates in the 800MHz and 1.9GHz PCS band.
Although CDMA was developed to rival TDMA for 2G mobile phones, it has come a long way since then. Today, GSM technology is more popular than CDMA due to its rich features. But in the purest technical sense, CDMA is more effective than GSM and TDMA. It is very cost-effective and requires less cell sites whereas giving three to five times more calling capacity than GSM and CDMA.
For many years this technology was being used by defense and military personel in order to establish secure connections. As opposed to FDMA and TDMA methods, CDMA benefits from a very wide range of signal broadcast which turns the job of sniffing and jamming a rather difficult one. CDMA is the common platform on which 3G technologies are being developed.
GPRS
The letters GPRS stand for General Packet Radio System, GPRS technology enabled much higher data rates to be conveyed over a cellular network when compared to GSM that was voice centric.
GPRS became the first stepping-stone on the path between the second-generation GSM cellular technology and the 3G. With GPRS technology offering data services with data rates up to a maximum of 172 kbps, facilities such as web browsing and other services requiring data transfer became possible. Although some data could be transferred using GSM, the rate was too slow for real data applications.
GPRS benefits
GPRS technology brings a number of benefits for users and network operators alike. It was widely deployed to provide a realistic data capability via cellular telecommunications technology.
GPRS technology offered some significant benefits:
Speed: One of the headline benefits of GPRS technology is that it offers a much higher data rate than was possible with GSM.
Packet switched operation: Unlike GSM which was used circuit switched techniques, GPRS technology uses packet switching in line with the Internet. This makes far more efficient use of the available capacity, and it allows greater commonality with Internet techniques.
Always on connectivity: A further advantage of GPRS is that it offers an "Always On" capability. When using circuit switched techniques, charges are based on the time a circuit is used, i.e. how long the call is. For packet switched technology charges are for the amount of data carried as this is what uses the services provider's capacity. Accordingly, always on connectivity is possible.
More applications: The packet switched technology including the always on connectivity combined with the higher data rates opens up many more possibilities for new applications. One of the chief growth areas that arose from GPRS was the Blackberry form of mobile or PDA. This provided for remote email applications along with web browsing, etc.
Capex and opex: The Capital expenditure (capex) and operational expenditure (opex) are two major concerns for operators. As GPRS was an upgrade to existing GSM networks (often implemented as a software upgrade achieved remotely), the capital expenditure for introducing GPRS technology was not as high as deploying a complete new network. Additionally opex was not greatly affected as the basic basestation infrastructure remained basically the same. It was mainly new core network elements that were required.
The GSM and GPRS elements of the system operate separately. The GSM technology still carries the voice calls, while GPRS technology is sued for the data. As a result voice and data can be sent and received simultaneously.
3G technologies
3G wireless technology represents the convergence of various 2G wireless telecommunications systems into a single uniform global system which includes terrestrial and satellite components in its functioning. 3G or the third-generation wireless refers to near future developments in personal & business wireless technology, especially relating to mobile communications. 3G or The Third Generation will usher in many benefits as roaming capability, broad bandwidth and high speed communication (upwards of 2Mbps).
3G network technology became available for commercial use first in Japan in 2001 and was followed by availability in South Korea and European countries Network operators & telecommunications service providers are embracing the recently adopted global third generation (3G) wireless standards in order to cater to emerging user demands and to offer new services to their customers.3G wireless technology represents a shift from voice-centric services to multimedia-oriented like video, voice, data, fax services.
The most interesting & useful aspect of 3G wireless technology is its ability to unify existing cellular standards such as GSM, CDMA and TDMA.
3G technology features that are meaningful to consumers fall into two broad classifications. The first is data rates, which refers to the rate at which 3G devices can transfer data through 3G networks. Cell phones and related devices can regularly access the Internet and are capable of playing music and displaying videos. Because video and audio file sizes can be large, higher data transfer rates for files being downloaded from the Internet provide a better user experience. The second set of 3G features relates to security. Because consumers may send and receive confidential information from their cell phones, security for wireless communications is essential. 3G security features are intended to address that need.
VOIP
VoIP will allow users to user their broadband connection to make phone calls over the Internet. The widespread use of VoIP has caused a revolution in the phone industry. With the VoIP service giving users the chance to make phone calls over the internet it is easy to see why this has rocked the telecom industry.
VoIP at present is becoming the most cost effective way to make long distance telephone calls. Before VoIP telephone service providers had a strong hold on lucrative and 99% of the time over priced long distance services.
Due to the introduction of VoIP the long distance calling market has began to open to up to competition. The main reason for this is that most Internet users will begin implementing VoIP. The main reason being that VoIP is the most cost effective way to make long distance telephone calls.
VoIP Development Process
Over the last 10 year VoIP has been slowly developing. In the early days computer users were able to talk to one another through their computers. You were only able to do this if you had a voice enabled computer with good Internet connection and you would
need to have a software program installed on your computer.
The main advantage to this was that it allowed user to be able to contact anyone from around the world for free aslong as they had the same setup as you.
The disadvantages to this system were that sound quality was never great, broadband was not being widely used and the user you were trying to contact would have to be online.
Today's VoIP has made these problems a thing of the past.
The two things that were required to make VoIP technology appeal to the wide spread market have been accomplished. Firstly, Broadband is now a widly used internet service. This allows users to have a stable internet connection that can always be on. Secondly the VoIP industry has been able to develop a simple and in-expensive way of integrating the IP network (aka Internet) with a traditional telephone system. This means that VoIP users are able to use their own telephone to call anyone else in the world who has the traditional telephone connection.
The major advantage of VoIP
Low cost, with no significant decrease in voice quality.
VoIP subscriber doesn't require a traditional phone line. Instead, you are assigned a phone number by your VoIP provider.
An additional important benefit is the flexibility and portability of VoIP phone service. With VoIP your individual telephone number is programmed into the converter that acts as a bridge between your internet connection and your regular telephone.
IPTV
Internet Protocol television (IPTV) is a system through which internet television services are delivered using the architecture and networking methods of the Internet Protocol Suite over a packet-switched network infrastructure, e.g., the Internet and broadband Internet access networks, instead of being delivered through traditional radio frequency broadcast, satellite signal, and cable television (CATV) formats.
IPTV services may be classified into three main groups: live television, time-shifted programming, and video on demand. It is distinguished from general Internet-based or web-based multimedia services by its on-going standardization process and preferential deployment scenarios in subscriber-based telecommunications networks with high-speed access channels into end-user premises via set-top boxes or other customer-premises equipment.
The IP-based platform offers significant advantages, including the ability to integrate television with other IP-based services like high speed Internet access and VoIP. An IP-based platform also allows significant opportunities to make the TV viewing experience more interactive and personalized. IPTV technology is bringing Video-on-demand (VoD) to television which permits a customer to browse an online program or film catalog, to watch trailers and to then select a selected recording.
IPTV is sensitive to packet loss and delays if the streamed data is unreliable. IPTV has strict minimum speed requirements in order to facilitate the right number of frames per second to deliver moving pictures. This means that the limited connection speed/bandwidth available for a large IPTV customer base can reduce the service quality delivered.
SUMMARY
