We are witnessing a huge interest for wireless devices (phones and PDAs) and services especially from professionals and people “on the move”. The Short Message Service (SMS), or paging, can be considered as a significant market success either for business or entertainment purposes. The ability to exchange SMS messages provides the convenience of being able to reach anyone anytime and anywhere in urgent situations. Unfortunately, SMS has fundamental limitations that make it an unsuitable technology above which to layer collaborative services. On the other hand, as wireless networks are bringing the idea of the “unplugged Internet”, a new standard, called Wireless Application Protocol (WAP), is emerging and making a significant impact in the mobile market.

2. System Description:

In recent times, chat rooms and instant messaging have proved enormously popular services. The predecessor to these services is Internet Relay Chat (IRC), which is an IP based service with sophisticated support for distributed collaboration. IRC provides a variety of mechanisms for users to collaborate across the internet with friends, colleagues and others both publicly and privately by creating and subscribing to various “channels”, or chat rooms, to exchange text message and file transfers.

2.1User Scenario:

From an end user point of view, the scenario we consider enables mobile users to chat by sending to each other instant messages. They can interact according to the instant responses of their friends/colleagues (“bodies”). In terms of functionality, the users interact with our WAP Chat application that supports a Wireless Markup Language (WML) interface enabling them to:

• Select and connect to a given chat server: users can choose among a list of available servers, the closest server to his/her current location (for best performance).

• Once connected to the chat server, the user can choose from a list of open channels provided by the server the discussion room (channel) that they wish to join.

• Scroll through the messages sent by other users on a channel.

• Type and send messages to the channel.

• Join another channel.

• Disconnect from the chat server.

At the start of a session, users are asked to input their contact information [optional]: name, email, photo, WML home page, etc. (figure 1A). When the user joins a channel, a hyperlinked list of the current subscribers to the channel is presented. The user can follow any of these links to view the contact information [optionally] entered by each subscriber. Once the user has joined a channel, he or she will be able to view the messages that have been sent to this channel. Accompanying each message is the name of the person that sent that message, with the name of the person hyperlinked back to their contact information (figure 1B).The user also receives a notification message indicating when others users join and leave the channel (figure 1C)

2.2 System Architecture

The system is based on a three tier architecture, but not in the traditional sense. A WAP client (tier 1) connects, via a WAP gateway, to the WWW server hosting the WAP Chat service (tier 2) which manages collaborators on a per-user-session basis. The WWW server hosting the WAP-Chat service then connects to the IRC server (tier 3) as specified by the user at the start of the session. The WAP-Chat WWW hosted application server manages user chat sessions which, in turn, can interact with multiple IRC servers. The WAP-Chat application server is also responsible for dynamically generating a rich WML interface for the WAP clients.

3.Security Hole At The WAP Gateway:

In general, the mobile customer and the e-merchant involved in an m-commerce transaction want (or should want) to ensure:

Confidentiality: Those messages are kept secret.

Authentication: That each party knows whom the other party is.

Message integrity: Those messages are passed unaltered from sender to receiver.

Replay attack prevention: That any unauthorized resending of messages is detected and rejected.

Non-repudiation: That neither party can later reject that the exchange took place.

All these issues must be addressed in a secure system. Indeed, it is the ambition of the WAP Forum to develop WAP into a standard that covers all relevant aspects of security, and some steps have been taking already with version 1.2.1 while version 2.0 goes a little bit further. For security, WAP provides a secure protocol for data transport: WTLS, Wireless Transport Layer Security. WTLS also contains features for authentication of both parties, as well as for non repudiation using message digests and digital signatures. Authentication of the user of a GSM phone may utilize the phone’s SIM card.

Finally, the definition of WML-Script includes a specification of a function library called a “crypto package”. This library contains a signing function, which can be used by a user to digitally sign a message, in the conventional manner in a Public Key Infrastructure. Thus WAP supports nonrepudiation of messages (such as a placement of an order) sent by a mobile WAP user. In the sequel, we merely discuss to what extent WAP achieves message confidentiality.

WAP’s two-stage security model: The basic security feature of WAP provides secrecy in the two half parts of the path that connects the WAP client and the web server: the (presumed) wireless path between the WAP client and WAP gateway, and the (presumed) wired path between the gateway and the web server (Figure 4). In the middle point constituted by the gateway, incoming data is decrypted; then while the data is in its original, un-encrypted form, it is subjected to some processing; and finally it is encrypted again before it is sent off along the other path. For encryption over the wired path, WAP simply relies on the Transport Layer Security (TLS) protocol, a widely used Internet standard. For encryption over the wireless path, WAP uses WTLS, which is in essence an adoption for wireless communication of the TLS protocol.

Thus prompted by the WAP client, the WSP layer at the gateway will initiate a TLS connection to the web server, in a way completely similar to setting up a connection between an ordinary web client and the server. This combination of WTLS and TLS provides secrecy (indeed, also integrity) over both halves of the WAP client / web server connection.

The crucial weakness is, of course, that all data transferred between the WAP client and the web server is decrypted at the WAP gateway, i.e., all data such as credit card numbers, etc. exists as free text in the memory of the gateway. Technical solutions, such as various programming techniques applied to the software that implements the WAP gateway, can make it somewhat difficult to get access to the data, but not impossible. Organizational solutions, such as tightening the security policy of the organization that hosts the WAP gateway, may limit access to the gateway and it’s data; but from the point of view of the two “end users” it is unsatisfactory that the privacy of their data is not under their own direct control.

4. Solutions For The WAP Security Problem:

4.1 Putting the gateway inside the “vault”:

The WAP gateway can be placed at the web server end of the connection, that is, inside the same security zone. When residing inside the local network of the merchant the gateway is protected against the outside world in a similar fashion to the way the web server is protected. A closer look at the business potential for the three stakeholders reveals that this solution does introduce further problems as well. Whether these will be solved is hard to say at the moment.

1. The Mobile Service Provider

For the Mobile Service Provider the main problem is a possible loss of business opportunities, e.g. “locking in” the customer to the provider’s m-portal. There are a number of possible WAP services that the MSP can offer only if it hosts the gateway, this being the MSP’s only way of ensuring that all data used in those services stays within the mobile network that the MSP is in control of. For instance, location dependent services utilize the MSP’s access to information from its own network about the exact location (cell) of the mobile phone. There may be strong business and security reasons for the MSP to not want such data to be available outside of the network. In the case of location information, the data is clearly sensitive, at the same time; the data may have a high business value, exactly because it is a prerequisite for certain services.

Moreover, this solution challenges the MSP to open its network to outsiders like the merchants running their own gateway. Each limitation on the MSP’s full control over the usage of its networks may introduce further traffic management problems.

2. The User

The user of the WAP client may witness degraded performance: The WAP protocols, which are tailored for the characteristics of wireless networks, are now used for the entire transport of the web content to the WAP client, instead of merely for the wireless part as intended. This may incur increased delays if there is congestion in the wired network. The end-user interface becomes less friendly, because the user of the WAP client will be forced to swap between gateways during Internet browsing. For example, the user that wants to buy from two distinct websites needs to use the WAP gateways of those sites. Swapping gateways raises two problems when changing the gateway profile of the phone. The gateway profile includes a dial-up phone number, the IP number of the gateway, etc.

3. The Merchant

The e-merchant is burdened with a complex piece of additional software (the gateway) that must be acquired and maintained. For a WAP gateway, maintenance work includes, for example, ensuring that the security-related software in the gateway is up-to-date, and updating the gateway to new versions of the WAP protocols. It is, however, not clear, whether the merchant will be further “burdened with handset provisioning and activation issues”.

4.2 Solution 2: Application level security on top of WAP:

This amounts to introducing security at a software layer above WAP, and considering WAP merely as a potentially insecure communication means (figure 5). Instead of using WAP’s protocol for secure transport (WTLS), security is taken care of by means of dedicated software running at the two “ends”, the mobile phone and the e-merchant’s web server. Such software could perform encryption in a way that eliminated the security hole at the gateway. In general, the approach would be in line with the conjecture about protocol design made in an end-to-end function, must be placed at a level where end-to-end control is available, i.e., at the application level.

While technically possible, above said solution would add a burden of extra complexity in the mobile phone. Indeed, the implementation of application-level security on top of WAP requires that sophisticated cryptographic functionality is made available to applications on the mobile WAP phone, either in the form of future enhancements of the WML Script Crypto Library or in other ways. It should be noted that the single function for digitally signing a message, which is presently the only function contained in the library is insufficient. Specifically, the Crypto Library’s signing function is not useful for encryption of data, because in principle, everyone in possession of the WAP user’s public key can read a message that she has signed digitally.

Moreover, this approach would partly neutralize most of the optimization provided by the WAP gateway: there will be a loss of the benefits of the data conversion and compression taking place in the gateway to accommodate the limited bandwidth of the wireless network. To minimize this, a balanced approach may be to encrypt only small fragments of the data, not the data as a whole. This would allow the WAP gateway to perform compression, decompression, and compilation by providing access to the WML tags and WSP/HTTP commands in their original, unencrypted form.

4.3 Solution 3: Enabling internet on the mobile device:

The third and last approach is to re-design the WAP protocol to not use a gateway, and employ the existing Internet standards, including the transport protocol (TCP), for the entire wired and wire-less part of a connection. By definition, this solves the security problem introduced by the gateway. This change of design has been proposed by the WAP Forum for version 2.0 of the WAP protocol. The standard now allows a range of different gateways, corresponding to having the conversion between the two protocol stacks anywhere from the top to the bottom of the stack.

At the top layers, the gateway works like the traditional WAP gateway taking care of the functions mentioned, and at the bottom layer it works like a traditional bridge/router. Whereas a TCP level gateway allows for two versions of TCP, one for the wired and another for the wireless network, on the top of which a TLS channel can be established all the way from the mobile device to the server.

The move away from top level conversion constitutes a fundamental change of design, which does away not only with security problem, but also the optimization for the wireless network, made possible by the gateway. Discarding the WAP gateway makes it possible to attain the same high level of security for an m-commerce transaction as that of an e-commerce transaction on the ordinary web using full end-to-end encryption. Indeed, for WAP to discard the WAP gateway would turn the (fully) WAP enabled mobile phone into an ordinary Internet device.

Besides the cost of deploying a full Internet protocol stack in the mobile phone, this solution enforces additional messages to be send between the device and the Internet. A simple request for a WML document must – in contrast to the gateway-based WAP solution – wait for a DNS-lookup to derive the appropriate IP-number from the symbolic name in the original request. The gateway based solution only has this cost over the wired Internet, when the gateway converts the WAP request to an HTTP-request. A minor optimization would be to utilize a caching DNS server at the border between the wired and the wireless network.

5.Conclusion:

Mobile SMS messaging (or paging) can be considered as a significant market success. The ability to send text messages has proved enormously popular across many sectors of the market, in particular among younger people. A tremendous improvement over SMS, WAP-Chat is a novel service to be offered by operators for exchanging messages between mobile users. As we move forward to ubiquitous information access, the convergence of WAP and collaboration services will yield a range of new and exciting approaches for supporting mobile groups that may be potentially distributed around the world.

Although the security hole associated with the gateway is commonly recognized, the WAP Forum did not release its previous deliberations as to why it felt the gateway’s advantages would outweigh its disadvantages. The introduction and subsequent de-route of the WAP gateway – whether preconceived or not – has increased the complexity of the WAP standard, comprising variations both with and without the gateway. We foresee a future where all the communication oriented WAP standards are replaced by Internet standards, leaving only the application level protocols in WAE as WAP specifications. It is also interesting to observe how the old and open Internet technology is able to outperform a vendor provided network solution like WAP. One may hope that the significance of a fully open discussion and standardization process will be learned also by the vendors behind the semi-opened WAP Forum.

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A person with a Wi-Fi enabled device such as a computer, cell phone or PDA can connect to the Internet when in proximity of an access point. The region covered by one or several access points is called a hotspot. Hotspots can range from a single room to many square  kilometres of  overlapping hotspots. Wi-Fi can also be used to create a mesh network and allows connectivity in peer- to- peer mode. Both architectures are used in community networks.

Discovery:

Despite the similarity between the terms ‘Wi-Fi’ and ‘Hi-Fi’, statements reportedly made by Phil Belanger of the Wi-Fi Alliance contradict the popular conclusion  that ‘Wi-Fi’ stands for ‘Wireless Fidelity. The precursor to Wi-Fi was invented in 1991 by NCR Corporation/AT&T (later Lucent & Agere Systems) in Nieuwegein, the Netherlands.   Vic Hayes, who was the primary inventor of Wi-Fi and has been named the  ‘father of  Wi-Fi,’ was involved in designing standards such as IEEE 802.11b, 802.11a and 802.11g.

Types:

Wi-Fi infrastructure devices typically fall into 3 categores as per it’s Application, with wireless being only one of many features.

1. Wi-Fi At Home
Home Wi-Fi clients come in many shapes and sizes, from stationary PCs to digital cameras. The trend today and into the future will be to enable wireless into every devices where mobility is prudent.

Wi-Fi devices are often used in home or consumer-type environments in the following manner:

• Termination of a broad band connection into a single router which services both wired and wireless clients, where cable connection can not be hooked up.
• Ad-hoc mode for client to client connections ,
• Built into non-computer devices to enable simple wireless connectivity to other devices or the Internet.

2. Wi-Fi in Business
In Business and Industry  current Technology of  Wi-Fi  is  moving toward ‘thin’ Access Points, with all of the intelligence housed in a centralized network appliance; relegating individual Access Points to be simply ‘dumb’ radios   utilizing true mesh topologies.

3.Wi-Fi in gaming
Some gaming consoles and hand helds make use of Wi-Fi technology to enhance the gaming experience   in local multiplayer as well as connecting to wireless networks for online game play or with separate adapter.

Technical information

Wi-Fi: How it Works

A typical Wi-Fi setup contains one or more Access Points (APs) and one or more clients. An AP broadcasts its SSID (Service Set Identifier, “Network name”) via packets that are called beacons, which are usually broadcast every 100 ms. The beacons are transmitted at 1 Mbit/s, and are of relatively might use signal strength to decide which of the two APs to make a connection to. The Wi-Fi standard leaves connection criteria and roaming totally open to the client. Since Wi-Fi transmits in the air, it has the same properties as a non-switched wired Ethernet network, and therefore collisions can occur  , which can not be   detected, and instead uses a packet exchange (RTS/CTS used for Collision Avoidance or CA) to try to avoid collisions.

Channels:
Wi-Fi uses the spectrum near 2.4 GHz, which is standardized, although the exact frequency allocations vary slightly in different parts of the world, as does maximum permitted power, except for 802.11a,which operates at 5 GHz.. However, channel numbers are standardized by frequency throughout the world, so authorized frequencies can be identified by channel numbers. The maximum number of available channels for Wi-Fi enabled devices are:

• 13 for Europe
• 11 for North America. Only channels 1, 6, and 11 are recommended for 802.11b/g to minimize interference from adjacent channels.
• 14 for Japan.

Standard Devices

A wireless access point connects a group of wireless devices to an adjacent wired LAN. An access point is similar to an ethernet  hub, relaying data between connected wireless devices in addition to a (usually) single connected wired device, most often an ethernet hub or switch, allowing wireless devices to communicate with other wired devices.

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WIMAX (world-wide interoperability for microwave access) is the IEEE 802.16 standards based wireless technology that  provides MAN (metropolitan area network) broad band  connectivity. WIMAX can offer a solution to what is  normally called the“last-ile”problem by connecting individual homes and business offices Communications. It is to be  less  expensive  than their  wired counterparts,such as digital  subscriber  lines (DSL).  This will  now  be  able  to  enjoy high-speed internet access since distance up to  30miles (50km) are supported.

“No wires, No rules”. Zooming down the highway, you will be able to use a laptop or PDA to check the weather or traffic a few miles ahead. From physical issues up to applications aspects, Mobile Ad hoc networking in Wi-Fi (wireless-fidelity) comprehensively covers all areas of the technology including protocols and models with an emphasis  on the most current research and development. To understand wireless technology trends and to see why non infrastructure-based  Mobile Ad hoc networks are poised to play an important role in the evolution of future wireless networks. It helps in the evolution path of different technology generations.

1.0 INTRODUCTION:

Wireless technology for computer users is nothing new. The first connections were established two decades ago. Adoption, though, has proceeded very slowly, mostly limited to a few specialized vertical markets, such as warehousing, education and retail.

Implementation has been slow for three reasons.first, the original wireless data rates were  too slow to serve  mainstream  users on a shared LAN. Although throughput did gradually increase, network speeds still drastically lagged those of wired  LANs.  Second,  proprietary, nonstandard  solutions  dominated  the marketplace, providing little interoperability  among devices, or the  peace of  mind for  users that come from  having multiple vendor options.third, these low speed proprietary solutions were very expensive compared to wired solutions.

In recent years, the situation has changed dramatically. In 1999, institute of Electrical and  Electronics Engineers(IEEE) ratified the 802.11b standard, offering data rates up to 11 megabits per second (mbps),similar to the 10 mbps connections that are common for  many Ethernet-based work groups. For the first time, wireless LANs became truly usable for most work environments and office applications.  Multiple vendors quickly came to support  the  802.11b  standard.  This  rapidly  drove down  costs, leading  to  increased demand and even greater vendor support.  In addition, the 802.11bstandard assured users of device interoperability. The Wireless Ethernet Compatibility of wireless  LAN  products based on the IEEE 802.11b specification and to promote the use of the standard across all  Market segments. With the rapid adoptions of the 802.11b standard,  users  began to have a choice of a  wide variety of  interoperable, low-cost, high –performance wireless equipment.

Perhaps most importantly, much type of organizations today sees tremendous value by adding wireless on to the corporate LAN. For years,  laptop and notebook computer shave  Promised  anytime,  any where  computing.But, with access to the  LAN  and the internet becoming such an integral part of business,  a wireless  connection  is  needed  to make true the  Promise of anytime, anywhere computing. Wireless devices enable users to be constantly connected from virtually anywhere: a desk, a conference room,  the coffee  shop, or another  Building on a corporate or academic campus. This ability provides users with maximum  flexibility, productivity and efficiency, while dramatically boosting collaboration and cooperation with colleagues, business partners and customers. In addition, wireless can bring LAN access to location where laying cable is difficult or expensive.

1.1 WiMax Standards

This figure shows how 802.16 broadband wireless systems have evolved over time. This diagram shows that the original 802.16 specification defined fixed broadband wireless service that operates in the 10-66 GHz frequency band. To provide wireless broadband service in lower frequency range, the 802.16A specification was created that operates in the 2-11 GHz frequency band. To provide both fixed and mobile service, the 802.16E specification was developed

Both 802.11a and 802.11g offer substantial improvements over the current 802 . 11b  standard, Because higher data rates deliver far greater performance and usability for devices on the wireless LAN.The one disadvantage is that the802.11aand 802.11g standards are not compatible because they use different frequency bands. further more, 802 11a is not compatible with the exiting installed base of 802.11b devices.
So, what should organizations do? This decision is critical as look a head to the future of their wireless infrastructure. it will guide their product choices and infrastructure capabilities for years to come.

2. Wimax: Broadband wireless access technology

wimax  is  a  wireless standards  developed by working group  of  institute of electrical And electronics engineers (IEEE). The first version, IEEE 802.16 activities were initiated by the national wireless electronics systems tested (N-WEST) of the u.s national institute of standards and technology.

The WIMAX from is a non-profit group that promotes 802.16 technology and certificates  compatibility and interoperability of broadband wireless access equipment that conforms to IEEE 80 2.16 & ETSIHIPERMAN standards. That standard offers an alternative [1] to cabled  access  networks, such as fiber  optic  links, coaxial  system using cable modems, and digital subscriber line (DSL) links or t1 links. This technology provides fast services, flexible, cost effective filling of the existing gaps of wired network and facility to create new services.
The IEEE has  established  many  wireless  standards  as  IEEE  802.15  for personal Area network (PAN), IEEE802.11  for local  area  network  (LAN),  IEEE802.16 for  local  area network (LAN), IEEE802.16  for  metropolitan  Area  network  (MAN).  Each standards represents the optimized technology for usage model.

2.1 – Typical WLAN Roaming

The topology of roaming cells may take on many forms but the essential building block is a collection of wireless devices with overlapping BSS. The overlapping wireless roaming cells mainly constitute an Access Point to Access Point (AP-to-AP) signal, Access Point-to-Wireless Client (AP-to-WC) linkage, or Wireless Client-to-Wireless Client (WC-to-WC) association. In a typical WLAN topology, the WC does not communicate directly with each other; they communicate with the access point. If a single BSS does not provide enough coverage, a number of wireless cells can be added to extend the range. (ESS).

One form of Wi-Fi™ Mesh comprise of a collection Root-AP overlapping to create wireless roaming cells.

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• offers cheap voice calls and high speed internet
• ensures  a boost for government security
• extend the currently limited coverage of public LAN    (hotspots) to citywide coverage (hot zones) the same technology being usable at home and on the move,
• blanket metropolitan areas for mobile data-centric service delivery,
• offer fixed broadband access in urban and suburban areas where copper quality is poor or unbundling difficult,
• bridge the digital divide in low-density areas where technical and economic factors make broadband deployment very challenging.

In addition to these uses, this paper will highlight other potential applications, such as telephony or an effective point-to-multipoint backhauling solution for operators or enterprises

1. INTRODUCTION

WiMAX is an acronym that stands for Worldwide Interoperability for Microwave Access, a  certification mark for products that pass conformity and interoperability tests for the IEEE 802.16 standards.  Products that pass the conformity tests for WiMAX are capable of forming wireless connections between them to permit the carrying of internet packet data. It is similar to   Wi-Fi in concept, but has   certain improvements that are aimed at improving performance and should permit usage over much greater distances. the WiMAX forum, backed by industry leaders, will encourage the widespread   adoption of   broadband  wireless access by establishing a brand for the technology and pushing.

2.  TECHNICAL ADVANTAGES OVER WIFI

Because IEEE 802.16 networks use the  same  Logical    Link   Controller (standardized by IEEE 802.2) as other LANs and WANs, it can be both bridged and routed to them.

An important aspect of the IEEE 802.16 is that it defines a MAC layer that supports multiple physical layer (PHY) specifications. This is crucial to allow equipment makers to differentiate their offerings. This is also an important aspect of why WiMAX can be described as a “framework for the evolution of wireless broadband” rather than a static implementation of wireless technologies. Enhancements   to   current   and   new technologies and potentially new   basic technologies incorporated into the PHY (physical layer) can be used. A converging trend is the use of multi-mode and multi-radio SoCs and system designs that are harmonized through the use of common MAC, system management, roaming, IMS and other levels of the system. WiMAX may be described as a bold attempt at forging many technologies to serve many needs across many spectrums.

The MAC is significantly different from that of Wi-Fi (and ethernet from which Wi-Fi is derived). In Wi-Fi, the MAC uses contention access—all subscriber stations wishing to pass data through an access point are competing for the AP’s attention on random basis. This can cause distant nodes from the AP to be repeatedly interrupted by less sensitive, closer nodes, greatly  reducing their throughput. By contrast, the 802.16 MAC is a scheduling   MAC   where   the subscriber station only has to compete once (for initial entry into the network).  After that it is allocated a time slot by the base station.  The time slot can enlarge and constrict, but it remains assigned to the subscriber station meaning that other subscribers are not supposed to use it but take their turn. This scheduling algorithm is stable under overload and oversubscription (unlike 802.11). It is also much more bandwidth efficient. The scheduling algorithm also allows the base station to control Quality of Service by balancing the assignments among the needs of the subscriber stations. A recent addition to the WiMAX standard is underway which will add full capability by enabling WiMAX nodes to simultaneously operate in “subscriber station” and “base station” mode. This will blur that initial distinction and allow for widespread adoption of WiMAX based mesh networks and promises widespread WiMAX adoption. The original WiMAX standard, IEEE 802.16, specifies WiMAX in the 10 to 66 GHz range. 802.16a added support for the 2 to 11 GHz range, of which most parts are already unlicensed internationally and only very few still require domestic licenses. Most business interest will probably be in the 802.16a standard, as opposed to licensed frequencies. The WiMAX specification improves upon many of the limitations of the Wi-Fi standard by providing increased bandwidth and stronger encryption. It also aims to provide connectivity between network endpoints without direct line of sight in some circumstances. The details of performance under non-line of sight (NLOS) circumstances are unclear as they have yet to be demonstrated. It is commonly considered that spectrum under 5-6 GHz is needed to provide reasonable NLOS performance and cost effectiveness for PtM (point to multi-point) deployments.

3. HOW WIMAX WORKS

In practical terms, WiMAX would operate similar to WiFi but at higher speeds, over greater distances and for a greater number of users. WiMAX could potentially erase the suburban and rural blackout areas that currently have no broadband Internet access because phone and cable companies have not yet run the necessary wires to those remote locations.

A WiMAX system consists of two parts:

A WiMAX tower, similar in concept to a cell-phone tower – A single WiMAX tower can provide                  coverage to a very large area — as big as 3,000 square miles (~8,000 square km). A WiMAX receiver – The receiver and antenna could be a small box or PCMCIA card, or they could be built into a laptop the way WiFi access is today.

A WiMAX tower station can connect directly to the Internet using a high-bandwidth, wired connection (for example, a T3 line). It can also connect to another WiMAX tower using a line-of-sight, microwave link. This connection to a second tower (often referred to as a backhaul), along with the ability of a single tower to cover up to 3,000 square miles, is what allows WiMAX to provide coverage to remote rural areas.  What this points out is that WiMAX actually can provide two forms of wireless service:

There is the non-line-of-sight, WiFi sort of service, where a small antenna on your computer connects to the tower. In this mode, WiMAX uses a lower frequency range — 2 GHz to 11 GHz (similar to WiFi). Lower-wavelength transmissions are not as easily disrupted by physical obstructions — they are better able to diffract, or bend, around obstacles

There is line-of-sight service, where a fixed dish antenna points straight at the WiMAX tower from a rooftop or pole. The line-of-sight connection is stronger and more stable, so it’s able to send a lot of data with fewer errors. Line-of-sight transmissions use higher frequencies, with ranges reaching a possible 66 GHz. At higher frequencies, there is less interference and lots more bandwidth.  WiFi-style access will be limited to a 4-to-6 mile radius (perhaps 25 square miles or 65 square km of    coverage, which is similar in range to a cell-phone zone). Through the stronger line-of-sight antennas, the WiMAX transmitting station would send data to WiMAX-enabled computers or routers set up within the transmitter’s 30-mile radius (2,800 square miles or 9,300 square km of coverage.

4. GLOBAL AREA NETWORK

The final step in the area network scale is the global area network (GAN). The proposal for GAN is IEEE 802.20. A true GAN would work a lot like today’s cell phone networks, with users able to travel across the country and still have access to the network the whole time. This network would have enough bandwidth to offer Internet access comparable to cable modem service, but it would be accessible to mobile, always-connected devices like laptops or next-generation cell phones). This is what allows WiMAX to achieve its maximum range.

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authentication of bluetooth using biometrics.doc (451 KB)

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We live in the age of information.  Data is the most valuable resource of an enterprise.  In today’s competitive global business environment, understanding and managing enterprise wide information is crucial for making timely decisions and responding to changing business conditions.  Many companies are realizing a business advantage by leveraging one of their key assets – business Data.  There is a tremendous amount of data generated by day-to-day business operational applications.  In addition there is valuable data available from external sources such as market research organizations, independent surveys and quality testing labs.  Studies indicate that the amount of data in a given organization doubles every 5 years.

Data warehousing has emerged as an increasingly popular and powerful concept of applying information technology to turn these huge islands of data into meaningful information for better business.  Data mining, the extraction of hidden predictive information from large databases is a powerful new technology with great potential to help companies focus on the most important information in their data warehouses.  Data mining tools predict future trends and behaviors, allowing businesses to make proactive, knowledge-driven decisions.
This paper describes the practicalities and the constraints in Data mining and Data warehousing and its advancements from the earlier technologies.

INTRODUCTION

Data Warehousing

• A data warehouse can be defined as any centralized data repository which can be queried for business benefit
• Warehousing makes it possible to
  • Extract archived operational data
  • Overcome inconsistencies between different legacy data formats
  • Integrate data throughout an enterprise, regardless of location, format, or communication requirements
  • Incorporate additional or expert information

Data Mining

Data mining is not an “intelligence” tool or framework, typically drawn from an enterprise data warehouse is used to analyze and uncover information about past performance on an aggregate level. Data warehousing and business intelligence provide a method for users to anticipate future trends from analyzing past patterns in organizational data. Data mining is more intuitive, allowing for increased insight beyond data warehousing. An implementation of data mining in an organization will serve as a guide to uncover inherent trends and tendencies in historical information, as well as allow for statistical predictions, groupings and  Classification of data.

Typical data warehousing implementations in organizations will allow users to ask and answer questions such as “How many sales were made, by territory, by sales person between the months of May and June in 1999?” Data mining will allow business decision makers to ask and answer questions, such as “Who is my core customer that purchases a particular product we sell?” or “Geographically, how well would a line of products sell in a particular region and who would purchase them, given the sale of similar products in that region.

WHAT IS DATA MINING?

Generally, data mining (sometimes called data or knowledge discovery) is the process of analyzing data from different perspectives and summarizing it into useful information – information that can be used to increase revenue, cuts costs, or both. Data mining software is one of a number of analytical tools for analyzing data. It allows users to analyze data from many different dimensions or angles, categorize it, and summarize the relationships identified. Technically, data mining is the process of finding correlations or patterns among dozens of fields in large relational databases.

Although data mining is a relatively new term, the technology is not. Companies have used powerful computers to sift through volumes of supermarket scanner data and analyze market research reports for years. However, continuous innovations in computer processing power, disk storage, and statistical software are dramatically increasing the accuracy of analysis while driving down the cost.

WHAT IS DATA WAREHOUSING?

Dramatic advances in data capture, processing power, data transmission, and storage capabilities are enabling organizations to integrate their various databases into data warehouses. Data warehousing is defined as a process of centralized data management and retrieval. Data warehousing, like data mining, is a relatively new term although the concept itself has been around for years. Data warehousing represents an ideal vision of maintaining a central repository of all organizational data. Centralization of data is needed to maximize user access and analysis. Dramatic technological advances are making this vision a reality for many companies. And, equally dramatic advances in data analysis software are allowing users to access this data freely. The data analysis software is what supports data mining.

According to Bill Inman, author of Building the Data Warehouse and the guru who is widely considered to be the originator of the data warehousing concept, there are generally four characteristics that describe a data warehouse:

1. Subject-oriented: data are organized according to subject instead of application e.g. an insurance company using a data warehouse would organize their data by customer, premium, and claim, instead of by different products (auto, life, etc.). The data organized by subject contain only the information necessary for decision support processing.
2. Integrated: When data resides in many separate applications in the operational environment, encoding of data is often inconsistent. For instance, in one application, gender might be coded as “m” and “f” in another by 0 and 1. When data are moved from the operational environment into the data warehouse, they assume a consistent coding convention e.g. gender data is transformed to “m” and “f”.
3. Time-variant: The data warehouse contains a place for storing data that are five to 10 years old, or older, to be used for comparisons, trends, and forecasting. These data are not updated.

An Overview of Data Mining Techniques:
This overview provides a description of some of the most common data mining algorithms in use today. We have broken the discussion into two sections, each with a specific theme:
1)    Classical Techniques such as statistics, neighborhoods and clustering, and
2)    Next Generation Techniques such as trees, networks and rules.
Each section will describe a number of data mining algorithms at a high level, focusing on the “big picture” so that the reader will be able to understand how each algorithm fits into the landscape of data mining techniques.

HOW DO DATAMINING AND DATAWAREHOUSING WORK TOGETHER??
Extracting meaningful information from numerous databases and cross-referencing it to find patterns, trends and correlations that might otherwise be overlooked is called “data mining.” Assembling the information in one place is called “data warehousing.”

1. All the information is stored in Information repositories.
2. Data warehouse takes the cleaned and integrated data.
3. The data taken by Data warehouse is selected and transformed and the useful data is sent through Data mining.
4. The data, which is sent through data mining is evaluated and presented.

APPLICATIONS

Data Warehousing

• Insulate data – i.e. the current operational information
  • Preserves the security and integrity of mission-critical OLTP applications
  • Gives access to the broadest possible base of data.
• Retrieve data – from a variety of heterogeneous operational databases
  • Data is transformed and delivered to the data warehouse/store based on a selected model (or mapping definition)
  • Metadata – information describing the model and definition of the source data elements
• Data cleansing – removal of certain aspects of operational data, such as low-level transaction information, which slow down the query times.
• Transfer – processed data transferred to the data warehouse, a large database on a high performance box.

Data Mining

• Medicine – drug side effects, hospital cost analysis, genetic sequence analysis, prediction etc.
• Finance – stock market prediction, credit assessment, fraud detection etc.
• Marketing/sales – product analysis, buying patterns, sales prediction, target mailing, identifying `unusual behavior’ etc.
• Knowledge Acquisition
• Scientific discovery – superconductivity research, etc.
• Engineering – automotive diagnostic expert systems, fault detection etc.

ADVANTAGES:

1. Enhances end-user access to a wide variety of data.
2. Business decision makers can obtain various kinds of trend reports e.g. the item with the most sales in a particular area / country for the last two years.

A data warehouse can be a significant enabler of commercial business applications, most notably Customer relationship Management (CRM).

DISADVANTAGES:

Data mining systems rely on databases to supply the raw data for input and this raises problems in that databases tend be dynamic, incomplete, noisy, and large. Other problems arise as a result of the adequacy and relevance of the information stored.

Limited Information
A database is often designed for purposes different from data mining and sometimes the properties or attributes that would simplify the learning task are not present nor can they be requested from the real world. Inconclusive data causes problems because if some attributes essential to knowledge about the application domain are not present in the data it may be impossible to discover significant knowledge about a given domain. For example cannot diagnose malaria from a patient database if that database does not contain the  red blood cell count of the patients.

Missing data can be treated by discovery systems in a number of ways such as;

• Simply disregard missing values
• Omit the corresponding records
• Infer missing values from known values
• Treat missing data as a special value to be included additionally in the attribute domain
• Or average over the missing values using Bayesian techniques.

FUTURE VIEWS

The future of data mining lies in predictive analytics. The technology innovations in data mining since 2000 have been truly Darwinian and show promise of consolidating and stabilizing around predictive analytics. Variations, novelties and new candidate features have been expressed in a proliferation of small start-ups that have been ruthlessly culled from the herd by a perfect storm of bad economic news. Nevertheless, the emerging market for predictive analytics has been sustained by professional services, service bureaus (rent a recommendation) and profitable applications in verticals such as retail, consumer finance, telecommunications, travel and leisure, and related analytic applications. Predictive analytics have successfully proliferated into applications to support customer recommendations, customer value and churn management, campaign optimization, and fraud detection. On the product side, success stories in demand planning; just in time inventory and market basket optimization are a staple of predictive analytics. Predictive analytics should be used to get to know the customer, segment and predict customer behavior and forecast product demand and related market dynamics. Be realistic about the required complex mixture of business acumen, statistical processing and information technology support as well as the fragility of the resulting predictive model; but make no assumptions about the limits of predictive analytics. Breakthroughs often occur in the application of the tools and methods to new commercial opportunities.

CONCLUSION:
Comprehensive data warehouses that integrate operational data with customer, supplier, and market information have resulted in an explosion of information. Competition requires timely and sophisticated analysis on an integrated view of the data. However, there is a growing gap between more powerful storage and retrieval systems and the users’ ability to effectively analyze and act on the information they contain. Both relational and OLAP technologies have tremendous capabilities for navigating massive data warehouses, but brute force navigation of data is not enough. A new technological leap is needed to structure and prioritize information for specific end-user problems. The data mining tools can make this leap. Quantifiable business benefits have been proven through the integration of data mining with current information systems, and new products are on the horizon that will bring this integration to an even wider audience of users.

• Data mining has a lot of potential
• Diversity in the field of application
• Estimated market for data mining is $500 million

REFERENCES:

Books Referred:
a.  Data Mining: concepts and techniques-Jiawei Han
b.  Data Mining Techniques- Arun k. Pujari.
c. Decision Support and Data Warehouse systems-Efrem G.Mallach

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This paper attempts to investigate the approach of embedded systems. The embedded system is a combination of computer hardware, software and perhaps additional mechanical or other parts, designed to perform a specific function within a given time frame.

INTRODUCTION:
An embedded system is a special-purpose computer system built into a larger device .An embedded-system is typically required to meet very different requirements than a general-purpose personal computer Two major areas of differences are cost and power consumption. Since many embedded systems are produced in the tens of thousands to millions of units range, reducing cost is a major concern. Embedded systems often use a (relatively) slow processor and small memory size to minimize costs.

Some of the attributes of the coming era:

1. The number of smart devices ( i.e., products with embedded operating systems inside ) will grow exponentially, reaching numbers in the billions.
2. The choice of CPU will be more a matter of cost than technology or a architecture
3. Nearly all devices will have connectivity, whether wired or wireless.
4. Most devices will have the ability to be upgraded or repaired remotely, by downloading new firmware or software.

Most devices will have specific rather than general-purpose functionality, so their users application software will be defined by the manufactures (rather than loaded by their). This needs to, “minimize cost and maximize specialization”creates the opportunity for embedded systems.

This peer reviewed paper has been published by the Pentagram Research Centre (p) limited. Responsibility of contents of this paper rests upon the authors and not upon pentagram research center (p) limited. Copies can be obtained from the company for a cost.

Embedded systems are becoming all pervasive. Every microwave has one. A cellular hand phone has two. A luxury Mercedes car has around 40. The latest Boeing 777-302,will have tens of dozens-we’re talking about the ubiquitous microprocessor chips and their associated peripheral devices.

To cite other examples, embedded software allows your washing machine to choose speed according to the type of cloth, gives thinking power to the microwave, acts like a music conductor in the car engine and pushes rocket launchers into space. The embedded system generally comprises topics like real time embedded digital signal processing, microprocessor architecture programming concepts; Real-time Operating System (QXN, RT Linux, V x Works); Micro controllers; Embedded Systems Programming Data Communication Networking, C concepts and linux among others.

START UP:
All embedded systems have start-up code. Usually it disables interrupts, sets of up the electronics, tests the computer (RAM, CPU and software), and then starts the application code. Many embedded systems recover from short-term power failures by skipping the self-tests if the software can prove they were done recently. Restart times under a tenth of a second are common.

‘Embedded systems’ has come to mean “micro-controller programming”. With the increasing proliferation of embedded systems, and advances in hardware and software technologies and the blurring of the boundary between them we need a more meaning-ful glimpse into this area. “Embedded systems’ addresses this need and brings out the issues in building modern-embedded systems.

DESIGN OF EMBEDDED SYSTEMS
The electronics usually uses either a microprocessor or a microcontroller some large are old systems use general-purpose mainframe computers are mini computers. Embedded systems design is getting complex, requiring intimate knowledge of both the hardware and software worlds. Cramming all those chips in a square centimetre of silicon real estate is more an art then a science. Getting the software to work with limited memory is often a struggle. Designers embedded systems strive to improve performance, reliability and cost effectiveness. Hardware and software choices are simultaneously considered. This is called co-design.

The goal is to produce an efficient implementation that satisfies-performance and cost requirements on the design the entire system on a chip-the SOC approach. Information appliances can be fabricated from custom SOC silicon .This has been successful in designing cellular hand phones where the high volume usually dictate this design strategy.

CHARACTERISTICS :
Two major areas of differences are cost and power consumption . Since many embedded systems are produced in the tens of thousands to millions of units range, reducing cost is a major concern. Embedded systems often use a (relatively) slow processor and small memory size to minimize costs.

The slowness is not just clock speed. The whole architecture of the computer is often intentionally simplified to lower costs.
For example embedded systems often use peripherals controlled by synchronous serial Interfaces, Which are ten to hundreds of times slower than comparable peripheral used in PCs. Programs on an embedded systems often must run with real time constrains with limited hard ware resources:

Often there is no disk drive, operating system , keyboard or screen. A flash drive may replace rotating media and a small keypad and LCD screen may be used instead of a PCs keyboard and screen. Firmware is the name for software that is embedded in hardware devices, e.g. in one or more ROM memory IC chips .

PLATFORM:
There are many different CPU architecture used in embedded designs. This in contrast to the disk top computer marke-t, which as of this writing (2003) is to limited just a few competing architectures , chieply intel’s x86,and the apple/Motorola/IBM power PC, used in the apple macintosh.
One common configuration for embedded system is the system on a chip, an application specific integrated circuit, for which the CPU was purchased as intellectual property to add to IC’s design.

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Over the past several years, the ease of copying and distributing copyrighted multimedia such as video, audio, image and software over the internet has increased significantly. With the emergence of peer-to-peer file sharing systems, this problem has only become more critical. These systems allow each PC to act as a file server for the network, sharing illegal multimedia data. As a result, there is a strong need to protect the rights of the authors and there are several possible solutions. One such solution would be cryptography which provides encryption and authentication of digital data thus enabling point to point information exchange and transactions. Yet, once the recipient validates and decrypts the data, the product can be subsequently stripped from any content identification, proof-of-ownership or other descriptive information, and further duplication and re-distribution can leave the rights holders powerless and royalty-less. Such re-distributions could have catastrophic implications for the entertainment industry, whose content has a long life span.

To overcome the problem faced in cryptography, a technology that enables some secure auxiliary information to be embedded into the original content through any channel, format or medium is made used. This is called as Digital Watermarking and could be applied to an image, an audio or a video signal.

A digital watermark is a piece of information which is embedded in the digital media and hidden in the digital content in such a way that it is inseparable from the data, this piece of information known as watermark. However, in any watermarking scheme the trade-off always exists between the robustness of the watermarking algorithm to signal processing attacks and the transparency of the watermark. It is known that as the energy of the watermark is increased, the probability of full recovery of the watermark is also increased. However, by increasing the watermark energy, we increase the noise in the signal and thus make the watermark audible.

Digital watermarking is just an adequate technology that tackles the security problems, which are not solvable by cryptography. Rooted in steganography which is the art and science of concealing the very existence of the secret message, digital watermarking provides proof and tracking capability to illicit copying and distribution of multimedia information. Which consists of three sorts of protections is needed in a secure multimedia transaction: secure communication, use contr`ol, and, a proof and tracking tool. They are complementary to protect the interests of all parties involved in a multimedia commerce transaction.

BASIC BLOCK DIAGRAM OF DIGITAL WATERMARKING FUNCTIONING

The general functioning of a typical watermark can be easily understood by means of the Fig 1. Presented below The original content (image, audio or video) is mixed with the modified version of the watermark to produce a suitable watermarked digital content at the sender’s end. At the receiving end, a normal human being perceives the image and is unable to appreciate the presence of watermark. However, a watermark detector at the receiving end extracts the encoded watermark from the content and decodes it to obtain the original watermark. In the given Fig. 1 following notations have been followed.

W = Watermark SW = Watermarked image SO= original information SO’= perceived information at the receiving end. W- Detected watermark information.

Thus the first step is to encode watermark bits into a form that will easily combine with the media data. For example in digital images, watermarks may be two dimension spatial patterns. This encoded information is then mixed with the original media content by means of watermark inserter. After insertion of the watermark also the resultant media looks similar to the original one using the peculiarities of the human visual system.

Some techniques use the principle that in eight bit gray images, changes to the least significant bit cannot be perceived by the human eye Turner. The human visual system looks at only the other seven bits thus ignoring the watermark information so the fidelity of the image is maintained. Other techniques convert the digital image into corresponding frequency domain and mix the watermark information in the high frequency part of the image. Human eye can perceive only low frequency components significantly thus ignoring the higher frequency components which are used by the watermark.

This is similar to the principle used in lossy compression as proposed by R.Schyndel. Methods using a single key are being employed but with different level of access and are termed ‘restricted key’ and ‘unrestricted key’ methods. No method using two different keys at sender and. receiver is yet known in the area of watermarking

WATERMARK CHARACTERISTICS

There are a number of important characteristics that watermarks exhibit. Some of the important ones are given below.

A. Fragility:

This is reverse of robustness. For specific applications where it is required that watermark in a text document should allow copying, but even if there is a small alteration
In text, the watermark should be destroyed. Thus if not detected, it can be ascertained that something wrong has happened with the original text. The watermarks may be designed to withstand various degrees of acceptable modifications in the watermarks on account of distortions in the media content. Here, watermark differs from a digital signature which requires a cent per cent match.

B. Tamper Resistance:

In addition to the normal signal distortions, the watermark should be resistant to distortions against the deliberate signal processing operations intended to remove the watermarks. A successful attack on a watermark system can damage or completely remove a watermark. Anticipation of such attacks and resistance against them comes in the category of tamper resistance.

C. Key restrictions:

When the keys are freely available to all detectors, it falls in the category of ‘unrestricted watermarks’ and if the key is available to a small no of detectors it comes in the category of ‘restricted watermarks’. Some watermarking methods create a unique key For each piece of data which is watermarked. Thus the owner of the data has to maintain a database of keys.

D. Fidelity:

This refers to the term imperceptible as it is referred in the literature of watermarks. The watermark should not be identified by normal viewing at the receiving end. It should also not cause any kind of perceptible distortion or deviation in the original media content. Either watermarks can be inserted into perceptually insignificant portions of the media, for example least significant bit or high frequency regions or they can also be kept in perceptually significant portions of the image using a new ‘spread spectrum technique. The second method is mostly used when robustness is the important concern.

E. Robustness:

The digital media content audio, video or digital image may undergo various kinds of distortions. Some of the common distortions are lossy compression; contrast Enhancement, alteration of colors, and modification of bass frequencies of audios, A/D or D/A conversions as well as standard geometric transformations like scaling, rotation, Cropping etc. After such distortions, the watermarks should be still present in the data and it should be possible to detect these watermarks correctly. It is proposed that watermarks exhibit robustness to deformations and distortions of image if they are placed inside the visually significant portions of the digital content rather than insignificant portions .F.Bartolini.

F. False positive rate:

In many applications, it may be required to distinguish the watermarked data from the un-watermarked data. The false positive rate of a watermark detection system is the probability that it will identify an un watermarked piece of data as containing a watermark.

G. Data Payload:

Data Payload of a watermark is the amount of information that it contains. If the watermark contains Nbits, then there are 2^N possible watermarks. Actually, there are 2^N +1 possibility because one possibility is that the watermark is not present.

H .Computational cost:

The computational cost refers to the cost of inserting and detecting watermarks in digital media content. This is very important when watermarks need to be inserted or detected in real time video or audio. The speed requirements of inserting and detecting watermarks is highly application dependent. Another important consideration while considering computational cost is scalability.

WATERMARK APPLICATION

There are a number of important applications that watermarks support; some of the important ones are given below.

A. Copy Control:

Watermark may contain information required by the Content owner that decided the policy of copying the Digital content. The information contained by the watermark may specify ‘content may not be copied’ or ‘only one copy’ etc. Subsequently, the devices used for copying the content may be required by law to contain watermark detector, which follows directives given by the content owner.

Today, many copyright infringements on the Internet occur unintentionally, resulting from Ignorance or carelessness. It is currently expensive and inconvenient to identify whether or not an image you have downloaded is copyright protected and even harder to find the correct right holders for licenses and permissions.

One of the traditional solutions is to place a visible logo or label at the corner of the image or overlay a transparent pattern over the image. Both of these methods, however, will eventually affect the quality of the image and limit the size of the message that can be placed. Moreover, they are easily tampered with.

By definition, public watermarking embeds traditional copyright notice into an image with a publicly known key or without a secret key, so that anybody can read it. Although public watermarking is not secure, it is much more difficult to remove than a visible label. Moreover, the failure of detection of the public watermark indicates that the image has been significantly tampered with and the user can be informed of the alteration.

B. Digital signatures:

Watermarks may be used to identify the owner of the content. By having this information the user may contact the owner for acquiring the legal rights to copy or using the Content.

To avoid any counterfeits being made from the source or original, multimedia works should be watermarked as early as possible. For example, the best way to protect a photographic image is to perform the ownership watermarking inside the digital camera.

Owner watermarking embeds the identifier or identifying information of the owner as well as of the multimedia work at the early phase of its creation. Since the ownership may be transferred and/or shared after creation, multiple watermarks should be allowed to identify the multiple owners in a multimedia work. A typical case is the productions of a multimedia title by compositing multiple images and other multimedia components (Audio segments, texts, video clips). Thus, both the composer and the owner of each Component want to identify their ownership in the composite work.

C. Fingerprinting:

Watermarks may be used to identify the content buyers. This may help in tracing illegal copies. When a digital media is distributed, it can contain the hidden and imperceptible information about the user, which can be detected by a watermark detector. Thus a licensed copy belonging to a specific user can be ascertained. This also resolves the possible conflicts as regards to the ownership of a digital or intellectual property. This thin is referred to as “Fingerprinting”.

Before delivering an image to the customer, the server ‘fingerprints’ the image using the customer’s identifier (such as name, or registration number) and transaction identifier(such as bill number and time).

In addition to the customer- and transaction-ID, access permissions (such as number of allowed copings) may be embedded too. The client’s rendering device will use this information to control the usage of the document.

To lighten the burden of the server, the client can also perform fingerprinting. This requires an authorized component residing in the client: whenever an image is decrypted and rendered (e.g. displayed, printed and saved as a file), the client’s identity information is embedded into this image. Recipient watermarking requires a high-speed watermark embedding process in order to accomplish a’ real-time’ online transaction. Moving the recipient watermarking from the server to the client can significantly improve the performance .referred to as “Fingerprinting”.

D. Authentication:

Watermark is used to provide authentification. It may be designed in such a way that, any possible alteration in the data either destroys the watermark or creates a mismatch between the content and the watermark that can easily be detected.

E. Broadcast monitoring:

Automatic identification of owners of data may be required to be done and used in systems responsible for monitoring the broadcasts. This may help in deciding the royalty Payments. It also helps in ensuring that commercials of a particular advertiser are played at right time and for aright duration.

F. Secret communication:

The technique of watermarking is also used in transmitting secretly information from source to destination in a hidden way. This method refers to steganography where the important or secret information may be hidden behind an image. Several public domain and shareware programs are available which use watermarking for secret communication.

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