Multimedia communication

Multimedia communication deals with the transfer, the protocols, services and mechanisms of discrete media data (such as text and graphics) and continuous media data (like audio and video) in/over digital networks.

Such a communication requires all involved components to be capable of handling a well-defined quality of service. The most important quality of service parameters are used to request (1) the required capacities of the involved resources, (2) compliance to end-to-end delay and jitter as timing restrictions, and (3) restriction of the loss characteristics.

Multimedia systems have attracted much attention during the last few years in the society as a whole and in the information technology field in particular. Multimedia communication comprises the techniques needed for distributed multimedia systems. To enable the access to information such as audio and video data, techniques must be developed which allow for the handling of audiovisual information in computer and communication systems.

We first describe in a more precise way what we mean by the term “multimedia”. Unfortunately,

“multimedia” has become a buzzword used to denote any kind of “new digital media” being manipulated or displayed by machines. This very imprecise (and very often employed) notion leads to a labelling of all types of media data computation, transmission, storage, manipulation and presentation with the term “multimedia”. Since the mid eighties we have proposed (and even from time to time we imposed) a much more crisp and restricted specification.

Multimedia itself denotes the integrated manipulation of at least some information represented

as continuous media data as well as some information encoded as discrete media data (such as text and graphics). The “manipulation” refers to the act of capturing, processing, communication, presentation and/or storage.

Hence “multimedia communications” deals with the transfer, the protocols, the services and the mechanisms of/for discrete and continuous media in/over digital networks. The transmission of digital video data over a dedicated TV distribution network is not multimedia as long as it does not allow the transfer of some type of discrete media data as well. A protocol designed to reserve capacity for continuous media data transmitted in conjunction with discrete media data over, e.g., an ATM-LAN, is certainly a multimedia communication issue.

Information processing in a time-sharing environment is performed without any hard time constraints. The system responds to a user interaction as soon as possible but often lacks support for realtime data. The use of discrete media still governs traditional computing, while the integration of continuous media into existing computer environments creates the new complexity of time-dependent data processing. ‘Correctness’ in multimedia communications is – in addition to the traditional computer communications error handling – determined by whether deadlines are met or not.

In networked multimedia applications various entities typically cooperate in order to provide the

mentioned real-time guarantees to allow data to be presented at the user interface. These requirements are most often defined in terms of Quality of Service (QoS). QoS is defined as the set of parameters which defines the properties of media streams. In accordance with [StNa95] we distinguish four layers of QoS: User QoS, Application QoS, System QoS and Network QoS. The user QoS parameters describe requirements for the perception of multimedia data at the user interface. The application QoS parameters describe requirements for the application services possibly specified in terms of media quality (like end-to-end delay) and media relations (like inter/intra-stream synchronization). The system QoS parameters describe requirements on the communication services resulting from the application QoS. These may be specified in terms of both quantitative (like bits per second or task processing time) and qualitative (like multicast, interstream synchronization, error recovery or ordered delivery of data) criteria. The network QoS parameters describe requirements on network services (like network load or network performance).

Internet

The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite (TCP/IP) to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks, of local to global scope, that are linked by a broad array of electronic, wireless and optical networking technologies. The Internet carries a vast range of information resources and services, such as the inter-linked hypertext documents of the World Wide Web (WWW) and the infrastructure to support electronic mail.

Most traditional communications media including telephone, music, film, and television are reshaped or redefined by the Internet, giving birth to new services such as Voice over Internet Protocol (VoIP) and IPTV. Newspaper, book and other print publishing are adapting to Web site technology, or are reshaped into blogging and web feeds. The Internet has enabled or accelerated new forms of human interactions through instant messaging, Internet forums, and social networking. Online shopping has boomed both for major retail outlets and small artisans and traders. Business-to-business and financial services on the Internet affect supply chains across entire industries.

The origins of the Internet reach back to research of the 1960s, commissioned by the United States government in collaboration with private commercial interests to build robust, fault-tolerant, and distributed computer networks. The funding of a new U.S. backbone by the National Science Foundation in the 1980s, as well as private funding for other commercial backbones, led to worldwide participation in the development of new networking technologies, and the merger of many networks. The commercialization of what was by the 1990s an international network resulted in its popularization and incorporation into virtually every aspect of modern human life. As of 2009, an estimated quarter of Earth's population used the services of the Internet.

The Internet has no centralized governance in either technological implementation or policies for access and usage; each constituent network sets its own standards. Only the overreaching definitions of the two principal name spaces in the Internet, the Internet Protocol address space and the Domain Name System, are directed by a maintainer organization, the Internet Corporation for Assigned Names and Numbers (ICANN). The technical underpinning and standardization of the core protocols (IPv4 and IPv6) is an activity of the Internet Engineering Task Force (IETF), a non-profit organization of loosely affiliated international participants that anyone may associate with by contributing technical expertise.

Types of Internet Communication

The Internet provides users with multiple means of communicating. Users may communicate with friends, colleagues, news reporters, editors and even strangers. Today there are more ways to reach out to people who were traditionally difficult to contact. As technology advances, the means of Internet communications becomes increasingly convenient and varied.

Social Networking

Members of social networking sites are able to send messages, comments, links, articles and pictures to other members of the site. Communication is not just between the sender and receiver, it is also available to other members who have access to browse your site. These other members may also make comments. This type of relationship is known as an Internet community.

Online Phone Calls

Skype.com is a website dedicated to providing online phone calls to other Skype members. This type of communication is known as Skype-to-Skype calling. Users communicate once they have downloaded the Skype software program from the Skype website. Skype also allows users to make video calls, through which users can see each other as they talk. Skype allows members to make low, per-minute Skype calls to landlines and cell phones.

Emails

Email, also known as electronic mail, not only allows you to communicate with other email users, but it also is a way to receive, for example, newsletters, coupons, daily inspirational quotes and job postings. Registered users have the ability to save drafts and past important emails for future reference.

Blog and Vlog

Blogging is a writer's way of expressing his thoughts, ideas, and social and political views online. Bloggers communicate to readers, who in turn make comments and send their links to other readers. Some bloggers gain notoriety through building a devout group of readers. Once bloggers have a following, they may be contacted by sponsors or they may propose sponsorship to interested companies. For instance, a food and wine blogger may obtain sponsorship from restaurants, food and wine magazines or online publications.

Vlogs are the same concept as blogs, except vlogs are digitally recorded. You can create a vlog on a digital video camera, digital camera, or cell phone. Video can then be uploaded onto your computer and shared with viewers.

Speak Out Loud

Online forums or message boards are an interesting way for participants to express their knowledge or views of a particular subject. Participants may speak, for example, on issues like new political agendas, their favorite sports teams or discuss their concerns about new technology. Message boards range from home improvement to medical experiences and procedures.

Your Opinion Matters

Online retail stores now allow prospective customers the opportunity to read buyer reviews before purchasing an item. This is an excellent tool for people who are skeptical about making a purchase. Reviewers describe their shopping experience and also rate purchased item according to various scales.

Readers of news articles are able to communicate with the public, news reporters and editors by expressing their views of online articles. Other readers may make comments about the article or the previous comments about the article. Comments about comments comprise what is known as a thread.

Satellite communication

What is Satellite Communication?

In satellite communication, signal transferring between the sender and receiver is done with the help of satellite. In this process, the signal which is basically a beam of modulated microwaves is sent towards the satellite. Then the satellite amplifies the signal and sent it back to the receiver’s antenna present on the earth’s surface. So, all the signal transferring is happening in space. Thus this type of communication is known as space communication.

Two satellites which are commonly used in satellite communication are Active and passive satellites.

1. Passive satellites: It is just a plastic balloon having a metal coated over it. This sphere reflects the coming microwave signals coming from one part of the earth to other part. This is also known as passive sphere. Our earth also has a passive satellite i.e. moon.

Active satellites: It basically does the work of amplifying the microwave signals coming. In active satellites an antenna system, transmitter, power supply and a receiver is used. These satellites are also called as transponders. The transmitters fitted on the earth generate the microwaves. These rays are received by the transponders attached to the satellite. Then after amplifying, these signals are transmitted back to earth. This sending can be done at the same time or after some delay. These amplified signals are stored in the memory of the satellites, when earth properly faces the satellite. Then the satellite starts sending the signals to earth. Some active satellites also have programming and recording features. Then these recording can be easily played and watched. The first active satellite was launched by Russia in 1957. The signals coming from the satellite when reach the earth, are of very low intensity. Their amplification is done by the receivers themselves. After amplification these become available for further use.

Microwave communication is possible only if the position of satellite becomes stationary with respect to the position of earth. So, these types of satellites are known as geostationary satellites.

What are the requirements for a satellite to be geostationary?

1. Its revolutionary direction must be same as that of the earth, i.e. from west to east.

2. The time period of satellite’s revolution must be same to the time period of the rotation of earth along its polar axis, which is equal to 24 hours.

3. The equatorial plane of earth must be coplanar with the orbital plane of the satellites revolution.

The name given to the orbit of the geostationary satellites is synchronous orbit. Due to this geostationary satellites are also called as geosynchronous satellites. Geosynchronous orbit is at a height of nearly 36000 km from the surface of earth.

These orbits are capable of giving a successful communication link between two stations present on the earth. These satellites can handle communication up to large distances. But it is impossible for a single geostationary satellite to cover the whole earth and provide a communication link. Due to curvature of earth the stations will be out of sight after covering some distance. If we want to cover the whole earth then we have to put three satellites onto the geosynchronous orbit. These satellites can cover the earth if all are inclined at an angle of 120o to each other.

Television communication

Television is one of the most popular forms of communication in the world today. Everyone in the world owns a television and watches it at least for 1 hour per day. This is a sign that this form of communication is successful. With televisions you can get your local stations, cable or choose from the many types of satellite providers. With these few great options, you will have access to this great form of communication in your own home.

By watching television shows, news and movies are a great way to keep up with the times and the newer forms of communication. Television is used for entertainment, fun, relaxation and to keep up with the the news around the world. This form of communication that gives you the opportunity to learn about the events around the world. Television does not have to bad for you if you watch the appropriate TV shows. There are many television shows that promote violence and other negative characteristics. Just because they are on TV does not mean that you have to watch it. Television provides information and entertainment to the masses in a way like no other form of communication does.

TVs can be purchased for as little as Rs.5000! This is a great deal for a TV that works well and can deliver a great form of communication directly to your home. Of course there are many great new technologies that have made it possible to create new forms of televisions for new generations. The plasma TV is one of the newest styles of televisions available today. This great new TV is allowing more improved forms of communication to be seen throughout the entire world.

Communication through TV has been going on for so many years now, that this is the reason for its improvement. With all the years of TV communication, there are so many people in the world that are not aware that they are taking part in any form of communication at all. This makes TV that much more effective. People are being affected by their TV and the shows that they watch without even realizing it. This can be a good thing, if you are being effected in a good way.

No matter what type of TV that you have you still experience the amazing communication that TV offers you. This form of communication is something that cannot be replaced and has been incredibly successful from the very beginning. TV is something that will never go out of style.

Mobile communication

Communication is one of the integral parts of science that has always been a focus point for exchanging information among parties at locations physically apart. After its discovery, telephones have replaced the telegrams and letters. Similarly, the term `mobile' has completely revolutionized the communication by opening up innovative applications that are limited to one's imagination. Today, mobile communication has become the backbone of the society. All the mobile system technologies have improved the way of living. Its main plus point is that it has privileged a common mass of society.

Evolution of Mobile Radio Communications

The rst wireline telephone system was introduced in the year 1877. Mobile communication systems as early as 1934 were based on Amplitude Modulation (AM) schemes and only certain public organizations maintained such systems. With the demand for newer and better mobile radio communication systems during the World War II and the development of Frequency Modulation (FM) technique by Edwin Armstrong, the mobile radio communication systems began to witness many new changes. Mobile telephone was introduced in the year 1946. However, during its initial three and a half decades it found very less market penetration owing to high costs and numerous technological drawbacks. But with the development of the cellular concept in the 1960s at the Bell Laboratories, mobile communications began to be a promising eld of expanse which could serve wider populations. Initially, mobile communication was restricted to certain social users and the cellular concept was never even dreamt of being made commercially available. Moreover, even the growth in the cellular networks was very slow. However, with the development of newer and better technologies starting from the 1970s and with the mobile users now connected to the Public Switched Telephone Network (PSTN), there has been an astronomical growth in the cellular radio and the personal communication systems. Advanced

Mobile Phone System (AMPS) was the rst U.S. cellular telephone system and it was deployed in 1983. Wireless services have since then been experiencing a 50% per year growth rate. The number of cellular telephone users grew from 25000 in 1984 to around 3 billion in the year 2007 and the demand rate is increasing day by day.

Present Day Mobile Communication

Since the time of wireless telegraphy, radio communication has been used extensively. Our society has been looking for acquiring mobility in communication since then. Initially the mobile communication was limited between one pair of users on single channel pair. The range of mobility was denied by the transmitter power, type of antenna used and the frequency of operation. With the increase in the number of users, accommodating them within the limited available frequency spectrum became a major problem. To resolve this problem, the concept of cellular communication was evolved. The present day cellular communication uses a basic unit called cell. Each cell consists of small hexagonal area with a base station located at the center

of the cell which communicates with the user. To accommodate multiple users Time Division multiple Access (TDMA), Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA) and their hybrids are used. Numerous mobile radio standards have been deployed at various places such as AMPS, PACS, GSM, NTT, PHS and IS-95, each utilizing di
erent set of frequencies and allocating different number of users and channels.

Fundamental Techniques

By definition, mobile radio terminal means any radio terminal that could be moved during its operation. Depending on the radio channel, there can be three different types of mobile communication. In general, however, a Mobile Station (MS) or subscriber unit communicates to a xed Base Station (BS) which in turn communicates to the desired user at the other end. The MS consists of transceiver, control circuitry, duplexer and an antenna while the BS consists of transceiver and channel multiplexer along with antennas mounted on the tower. The BS are also

linked to a power source for the transmission of the radio signals for communication and are connected to a xed backbone network. Figure 4.1 shows a basic mobile communication with low power transmitters/receivers at the BS, the MS and also the Mobile Switching Center (MSC). The MSC is sometimes also called Mobile Telephone Switching Oce (MTSO). The radio signals emitted by the BS decay as the signals travel away from it. A minimum amount of signal strength is needed in order to be detected by the mobile stations or mobile sets which are the hand-held

personal units (portables) or those installed in the vehicles (mobiles). The region over which the signal strength lies above such a threshold value is known as the coverage area of a BS. The xed backbone network is a wired network that links all the base stations and also the landline and other telephone networks through wires.

Radio Transmission Techniques

Based on the type of channels being utilized, mobile radio transmission systems may be classified as the following three categories which is also shown in Fig.4.2:

Simplex System: Simplex systems utilize simplex channels i.e., the communication is unidirectional. The rst user can communicate with the second user. However, the second user cannot communicate with the rst user. One example of such a system is a pager.

Half Duplex System: Half duplex radio systems that use half duplex radio channels allow for non-simultaneous bidirectional communication. The first user can communicate with the second user but the second user can communicate to the rst user only after the rst user has finished his conversation. At a time, the user can only transmit or receive information. A walkie-talkie is an example of a half duplex system which uses `push to talk' and `release to listen' type of switches.

Full Duplex System: Full duplex systems allow two way simultaneous communications. Both the users can communicate to each other simultaneously. This can be done by providing two simultaneous but separate channels to both the users. This is possible by one of the two following methods:

• Frequency Division Duplexing (FDD): FDD supports two-way radio communication by using two distinct radio channels. One frequency channel is transmitted downstream from the BS to the MS (forward channel).A second frequency is used in the upstream direction and supports transmission from the MS to the BS (reverse channel). Because of the pairing of frequencies, simultaneous transmission in both directions is possible. To mitigate self-interference between upstream and downstream transmissions, a minimum amount of frequency separation must be maintained between the frequency pair, as shown in Fig. 4.3.
• Time Division Duplexing (TDD): TDD uses a single frequency band to transmit signals in both the downstream and upstream directions. TDD operates by toggling transmission directions over a time interval. This toggling takes place very rapidly and is imperceptible to the user.

A full duplex mobile system can further be subdivided into two category: a single MS for a dedicated BS, and many MS for a single BS. Cordless telephone systems are full duplex communication systems that use radio to connect to a portable handset to a single dedicated BS, which is then connected to a dedicated telephone line with a specific telephone number on the Public Switched Telephone Network (PSTN). A mobile system, in general, on the other hand, is the example of the second category of a full duplex mobile system where many users connect among themselves via a single BS.

Telephone communication

Communication means have changed dramatically over the years, with the introduction of modern telecommunications such as faxes and email, but still the most widely used communication tool is the telephone. The telephone is a very powerful tool, especially when used within a business environment and many people underestimate its importance and more importantly, the importance of the person using it.

When a potential client phones a company, their first impression of that company is created by the person who answers the phone. In order to ensure that the caller develops a positive image within their mind, the person answering the call must be efficient, confident and capable of inspiring confidence in the caller. It is a very big responsibility but by examining existing skills and practising new ones this challenge can be met, and the standards maintained. Telephone communication is a routine, but important, component of every practice.

As with any form of communication, when speaking on the telephone, there are certain elements which will affect the ease with which you communicate and also the understanding of the message that you are trying to get across. Comparing the use of the telephone to such methods as letter writing or face to face meetings, it is easy to see that the telephone has a lot of limitations. There is no written word to read, therefore retention of what you have said is difficult. There is no body language, just your voice to make that important impression. Using the voice correctly involves paying special attention to three areas. These are.

1. Speed
2. Clarity
3. Tone

1. Speed

Speaking too fast automatically creates barriers, and confusion. The caller will find it difficult to grasp what you are trying to say. When making outgoing calls you are prepared and [hopefully] know what the call is about. The person at the other end of the line was probably not expecting the call and almost certainly was involved in something completely unrelated at the time.When answering calls, slow down, think before you answer any queries or questions.

2. Clarity

Avoid mumbling. Speak clearly and distinctly but avoid compensating for this by shouting.

3. Tone

Speed and Clarity may be fine but this means nothing without a positive tone. No matter how bad your mood is, don't let it show in your voice. Sound friendly and cheerful, even if it is killing you.

Listen!

Another important communication skill essential while on the telephone is listening. Listening to customers is perhaps one of the most important things that anybody can do. Ask questions and then step back. Try not to prompt too much. Allow them to have their say.

Fax Communication

What is Fax?

FAX is basically a technique of reproducing a document electronically at a distant place. FAX machine is an example of digital communication system. A fax (short for facsimile and sometimes called tele copying) is the telephonic transmission of scanned-in printed material (text or images), usually to a telephone number associated with a printer or other output device. The original document is scanned with a fax machine, which treats the contents (text or images) as a single fixed graphic image, converting it into a bitmap. In this digital form, the information is transmitted as electrical signals through the telephone system. The receiving fax machine reconverts the coded image and prints a paper copy of the document.

Uses of a fax machine:

(a) It sends all the data over the telephone lines. Even the images are converted into digitized form and then are sent over the telephone lines.

(b) It also does the task of receiving the digitized image information. Then it reconstructs the image by doing the decoding of the digitized image.

Some steps are followed to send the data through fax. These are:

1. Some sensors are used at the receiving ends to read the received paper.

2. Black and white spots are marked on the paper at the sending end. This is done to make the travelling of the data possible over telephone line.

3. A mechanism is used to understand this coming data in the form of black and white dots, and to reproduce the original document by reading these dots at the receiving end.

Today Group 3 facsimile machines are the most popular machines used by the majority. Those machines which belong to these groups are capable of communicating with similar machines of Group 3.

Let’s now discuss about these machines. These machines have a resolution of 8 pixels per inch. These machines use two distinct vertical resolutions. These can transmit data at a rate of 14400 bits per second. Sometimes the noise present over the line decreases the data rate up to some extent. These machines use a photodiode sensing array so that the complete line of the page can be scanned at a time. It consists of 1728 sensors. Paper illumination is also done to provide the clear view of the paper to the sensor.

Traditional modes of communication

The modem means of mass communication, press, radio, TV, telephone etc., are an integral part of today’s modern world, without which life can hardly be imaginable. But how did communication actually work before mass media came into being, and before the spreading of the P written Word? Taking a look at other cultures and our own past, opens up interesting fields of information.

1. It is unanimously recognised that communication is an essential element of each epoch and every society. Traditional forms of communication are for instance myths; storytelling; songs; proverbs; religious rituals; artistic, musical, dance and theatrical elements, as well as ornaments depicted on pottery textiles and wood. These forms differ greatly from each other, bemg characterised - among others - by their own particular society, and by economical, social and religious characteristics. Myths give witness to reflections and observations of nature and human beings. They convey a view of life, depicting the position of human being. On this basis, values and standard are shared and rules laid down conceming behaviour towards nature and relationships between men.

2. Traditional communication fulfils several functions, just to name a few:

a) The passing on of knowledge and experience (agricultural, social, botanical, meteorological, etc).

b) One further aspect of traditional communication is the conveyance of moral concepts: moral and social standards such as legal patterns which rule the coexistence of human being, their dealings with natural resources, and regulates their behaviour towards foreigners.

Examples are to be found in stories, songs and proverbs, in which virtues are rewarded and weaknesses punished. (What is to be understood by virtue or weakness is laid down by the respective society on grounds of its human and worldly concept).

c) Other myths and tales give the answer to questions of vital significance to human being, such as the sense in grief, of illness and death. These helped - and still help - by overcoming such situations.

d) Information concerning historical events concerning society as a whole, or ancestral tales serve to form the identity of a person or a society, and strengthen their solidarity.

Activities which from a utilitarian point of view seem meaningless (e.g. story-telling, dancing, singing, performing of religious ceremonies), play however a not unimportant role in the functioning of social order and the ensuring of economic foundations. In this way traditional communications serve finally the survival of the group itself. Traditional forms of communication are ritually repeated on special occasions, e.g. of annual or lifetime celebrations. In this way they renew and prove their worth and experience, and in so doing are communicated to the younger generation.

Traditional communication forms are a part of the culture of the relevant society. Tl-rey are familiar to the members, are used by them and understood by all. Very often they take the form of social events (e.g. parties, celebrations).

3. In comparison, in modem industrial society the content of knowledge and entertainment often falls apart; knowledge is often reduced to intellectual knowledge, while entertainment not seldom lacks a spiritual background.

Referentes to own culture and the connection between the communication content and own vital matters are - in this age of mass media - no longer given: Programmes are produced where financial hacking is available, with the result that both Indio children in the Andes, as well as slum-dwellers in the large cities of India, are - via foreign television - presented with programmes which not only give no answers to their problems, but wherein lie also the danger of foreign cultural infiltration.

4. These dangers and deficiencies however can be overcome through appropriate use of modem communication means: In this respect it is decisive that in all peoples and groups, increasing interest is shown in the use of modem media and to take part in respective training programmes. On the one hand this gives the possibility of authentically portraying the elements of traditional culture (e.g. entertainment, dance, song, etc.), through modem media. In this way, members of the respective cultures discover that they also are seen and heard, and their culture respected. On the other hand, today in all comers of the world, modem cultural basis organisations are becoming noticed. They themselves produce print- radio and video programmes, and in this way support the efforts of NGO’s and other groups in a responsibly fashioned present and future.

Those on the edge of society are no longer just passive consumers of programmes and information from a foreign world. They now have a mouthpiece through which they can make known their own perspectives.

As with traditional communication means, the connection between life and survival is given once again here, as well as the active participation and involvement of al1 groups in the task of solving problems. Communication is no longer a one-way-Street ruled by a dominant society. It would be

desirable if this type of media work could fmd its rightful place in society as a whole at national and intemational level, as also here the number of contributions received “from the South” are steadily diminishing.