mobile computing full report
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MOBILE COMPUTING
ABSTRACT:
Mobile computing has fast become an important new paradigm in today's world of networked computing systems. Ranging from wireless laptops to cellular phones and WiFi/Bluetooth-enabled PDAs to wireless sensor networks, mobile computing has become ubiquitous in its impact on our daily lives. The debut if iPhones and the proliferation of other handheld devices has spurred excitement and interest in this evolving field. In this seminars, we will study the state-of-the-art in both the research and commercial communities with respect to mobile computing. We will investigate standard protocols and platforms, the capabilities of today's commercial devices, and proposed next-generation solutions. In the process, we will seek to gain an improved understanding about where the field is headed, and what are the important remaining unanswered technical questions and challenges.
Mobile computing is a new style of computer access emerging at the intersection of the two currently dominant trends: producing portable computers in computer industry and wireless communications in telecommunication industry. This paper discusses some key issues involved in realizing a mobile wireless computing environment by examining the characteristics required of each main component: mobile computer, wireless communications network, and coordination software.
Mobile computing is becoming increasingly important due to the rise in the number of portable computers and the desire to have continuous network connectivity to the Internet irrespective of the physical location of the node. Mobile IP, the more popular global mobility solution, was designed to support mobility of a single host. Even though the same protocol can be applied in the case of network mobility, providing connectivity to mobile networks introduces many issues related to the scalability, security and QoS. Instead, a mobile network can be cited as a remote site, trying to establish secured communication with the home network. This view of mobile network solves many issues related to QoS, security and scalability. The objective of this paper is to explore the possibility of using different VPN techniques to provide connectivity for mobile networks and measure the corresponding end-to-end performance of real time traffic and best effort traffic patterns.

Presented by:
T.PRIYA (B.TECH-IT-2ND YEAR)
V.SARANYAH (B.TECH-IT-2ND YEAR)
CHETTINAD COLLEGE OF ENGINEERINAND
TECHNOLOGY, KARUR.
INTRODUCTION:
Mobile Computing is an umbrella term used to describe technologies that enable people to access network services anyplace, anytime, and anywhere. Ubiquitous computing and nomadic computing are synonymous with mobile computing. Information access via a mobile device is plagued by low available bandwidth, poor connection maintenance, poor security, and addressing problems. Unlike their wired counterparts, design of software for mobile devices must consider resource limitation, battery power and display size. Consequently, new hardware and software techniques must be developed. For example, applications need to be highly optimized for space, in order to fit in the limited memory on the mobile devices. For Internet enabled devices, the good old TCP/IP stack cannot be used; it takes too much space and is not optimized for minimal power consumption. Given the plethora of cellular technologies that have emerged in such a market, it becomes extremely difficult to provide support for inter-device communication.
A new hardware technology solution, Bluetooth, has been proposed to overcome this barrier. Any device with a Bluetooth chip will be able to communicate seamlessly with any other device having a similar chip irrespective of the communication technologies they might be using. For the sake of explanation, an analogy can be drawn between the Java Virtual Machine and Blue tooth.
In the recent past, cellular phone companies have shown an interesting growth pattern. The number of customers has been steadily increasing but the average airtime per user has slowed to a constant. To increase the user average connect time, many cellular providers have started providing data services on their networks which entices the user to use the mobile device for both voice and data communication. Typical data services include chat, e-mail, Internet browsing. An example of this type of service is SMS (Short Message Service). It is a data service in a GSM cellular network that allows the users to send a maximum of 160-character message at a time (similar to paging). Inherently, this service is not feasible for browsing, checking e-mail or chatting. GSM networks provide another service called GPRS (General Packet Radio Service) that allows information to be sent and received across the cellular network.
There has also been a recent effort defining common standards for providing data services on hand-held devices. WAP (Wireless Application Protocol) and KVM (Kilobyte Virtual Machine) deserve a mention here. WAP is a protocol suite that comprises of protocols tailored for small devices. WAP has been developed by the WAP Forum and runs over an underlying bearer protocol like IP or SMS. In the WAP model, a service provider operates a WAP gateway to convert Internet content to a miniaturized subset of HTML that is displayed by a mini-browser on the mobile device. Companies like Nokia, Ericsson and Motorola have already developed WAP enabled phones. As of now, these phones are available and functional mostly in Europe.
TECHNICAL AND OTHER LIMITATIONS OF MOBILE COMPUTING
Insufficient bandwidth
Mobile internet access is generally slower than direct cable connections, using technologies such as GPRS and EDGE, and more recently 3G networks. These networks are usually available within range of commercial cell phone towers. Higher speed wireless LANs are inexpensive, but have very limited range.
Security standards
When working mobile one is dependent on public networks, requiring careful use of VPNs.
Power consumption
When a power outlet or portable generator is not available, mobile computers must rely entirely on battery power. Combined with the compact size of many mobile devices, this often means unusually expensive batteries must be used to obtain the necessary battery life.
Transmission interferences
Weather, terrain, and the range from the nearest signal point can all interfere with signal reception. Reception in tunnels, some buildings, and rural areas is often poor.
Potential health hazards
More car accidents are related to drivers who were talking through a mobile device. Cell phones may interfere with sensitive medical devices. There are allegations that cell phone signals may cause health problems
MOBILE COMPUTING: IN-VEHICLE COMPUTING AND FLEET COMPUTING
Many commercial and government field forces deploy a ruggedized portable computer such as the Panasonic Toughbook or larger rack-mounted computers with their fleet of vehicles. This requires the units to be anchored to the vehicle for driver safety, device security, and user ergonomics. Ruggedized computers are rated for severe vibration associated with large service vehicles and off-road driving, and the harsh environmental conditions of constant professional use such as in Emergency medical services, fire and public safety.
Other elements that enables the unit to function in vehicle:
¢ Operating temperature: A vehicle cabin can often experience temperature swings from -20F to +140F. Computers typically must be able to withstand these temperatures while operating. Typical fan based cooling has stated limits of 95F-100F of ambient temperature, and temperature below freezing require localized heaters to bring components up to operating temperature(based on independent studies by the SRI Group and by Panasonic R&D).
¢ Vibration: Vehicles typically have considerable vibration that can decrease life expectancy of computer components, notably rotational storage such as HDDs.
¢ Daylight or sunlight readability: Visibility of standard screens becomes an issue in bright sunlight.
¢ Touchscreens: These enable users to easily interact with the units in the field without removing gloves.
¢ High-Temperature Battery Settings: Lithium Ion batteries are sensitive to high temperature conditions for charging. A computer designed for the mobile environment should be designed with a high-temperature charging function that limits the charge to 85% or less of capacity.
¢ External wireless Connections, and External GPS Antenna Connections: Necessary to contend with the typical metal cabins of vehicles and their impact on wireless reception, and to take advantage of much more capable external tranception equipment
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Several specialized manufacturers such as National Products Inc (Ram Mounts), Gamber Johnson and LedCo build mounts for vehicle mounting of computer equipment for specific vehicles. The mounts are built to withstand the harsh conditions and maintain ergonomics.
Specialized installation companies, such as TouchStar Pacific, specialize in designing the mount design, assembling the proper parts, and installing them in a safe and consistent manner away from airbags, vehicle HVAC controls, and driver controls. Frequently installations will include a WWAN modem, power conditioning equipment, and WWAN/WLAN/GPS/etc¦ transceiver antennæ mounted external to the vehicle.
FIVE TRENDS IN MOBILE COMPUTING
The next stage in mobile computing is to put some interesting plays on the stage. Okay, that is a strained comparison, but I recently attended Xconomy's Mobile Innovation in New England forum and came away impressed.
If you are in the mood to read the tweatstreams of the event, do a Twitter search on mobile. The event was sold out and speakers included Rich Miner, the managing partner of the new Google Ventures arm and Ted Morgan, CEO of Skyhook Wireless. Xconomy writer Wade Roush has a decent wrap-up of the wireless event.
Here are the five main trends I took away from the one day event -- which was one of the better events I've attended recently.
1. Appstore madness. As usual Apple has blazed the trail and now it is up to Microsoft, RIM and Google to catch up. Mobile devices and networks are simply a platform, it is up to the developers to come up with the cool apps that make a platform great. Maybe it has always been this way, but in the mobile space everyone got fixated on the device rather than the application. That is changing.
2. Business matters. Apple has never seemed to interested in the business to business marketplace. But, unlike consumers, a business will put its money where its strategy is. Business applications for mobile devices have been sorely lacking. That is changing.
3. The carriers may be finally getting it. The big carriers have been some of the biggest obstacles in getting the mobile application business moving. They were way too much in the "my way or the highway" mode of business partners. Now the carriers are suddenly interested in partnering. Carriers should do what carriers do best, build infrastructure and bill in small increments.
4. The mobile device is a platform, not an adjunct. Applications need to written for the smaller user interface and unique characteristics of the devices. Stop trying to squeeze down applications that were written for the big screen PC environment.
5. Your mobile phone knows where you and your friends are. The location determining capabilities of the mobile network continue to improve as the processing horsepower residing in the phone and on the network grows. The combination of the two will result in location aware applications that enhance social networks, banking and GPS-based services. Knowing the location of you and your friends also carries privacy concerns that need to be addressed upfront.
ADVANTAGES OF MOBILE COMPUTING
Computers are one of the major inventions of the world. The invention of computer has changed the world. During these days every field of life seems to be computerized. Later in the 21st century a new technology was introduced in the world known as mobile computing. Now-a-days computers are modified into mobile computers known as laptops.
A small introduction of mobile computing is that you can do your work in motion. In simple words it means that you can do your work while sitting anywhere in the world. You do not have to sit at one place to do your work.
Following are some of the advantages of mobile computing.
The main benefit of mobile computers is that you do not have to bind yourself to a certain place. You can do your work while sitting in a car or a train. You can communicate with other people while sitting anywhere in the world. You can chat online with your friends and family members while sitting on a beach. You can do your office work while sitting anywhere.
The second major benefit is related to the first benefit. When people can do their work while sitting anywhere they will do more work. This will play an important role in the economy of the country and the world.
During these days there is no problem for a student to search any information that he needs for his assignment. Many people use these mobile computers for entertainment. Children play video games on these computers.
TODAY'S BEST MOBILE WIRELESS NETWORKS
What is a Mobile Wireless Network?
A mobile wireless network is simply a computer network that is implemented without the use of wires. There are various types of wireless networks including wireless Personal Area Networks (PAN), wireless Local Area Networks (LAN), wireless Metropolitan Area Networks (MAN), and more. To enable people to access wireless networks, a variety of network service providers provide wireless network coverage to offices, public places, and other small workplaces.
Mobile wireless networks frequently involve the use of cellular phone networks connecting to an Internet Service Provider (ISP); thereby, enabling the user to connect to the internet. All wireless networks consist of radio communications services carried on between mobile stations or receivers and land stations, as well as by mobile stations communicating amongst themselves. The wireless network service providers, for example Sprint and Cisco, use a wireless access point device to provide wire-free network coverage in designated areas to users. This allows various mobile devices, such as smart phones and laptops, to connect to the mobile wireless network. Currently, smart phones are by far the most commonly used mobile computing devices.
¢ Trapeze Networks “ This Company™s mobile wireless LAN Mobility System is superior to many other networks. The LAN Mobility System enhances user productivity, introduces new efficiencies, and accelerates business response time. The system also delivers secure mobility and the company offers low cost solutions.
¢ Sprint “ Sprint is a leading innovator when it comes to wireless networks. One of Sprint™s recent wireless network innovations is its 3G (3rd generation) PCS Vision network. This innovative network is easy to use, reliable, secure, and reasonably fast. Additionally, because the network is 3G, it can be accessed anywhere as opposed to only being accessed in a wireless hot spot.
¢ Cisco Systems, Inc. “ The Cisco Unified Wireless Network addresses several mobile computing issues, such as wireless network security, network management, network control, and more. Cisco combines the best elements of wireless and wired networking to deliver secure and cost-effective wireless networks, all the while providing instant, real-time, reliable network access.
ACHIEVING THE BENEFITS OF MOBILE COMPUTING (MOBILE FRAMEWORK)
Mobile computing is an important, evolving technology. It enables mobile personnel to effectively communicate and interact with the fixed organizational information system while remaining unconstrained by physical location. Mobile computing may be implemented using many combinations of hardware, software, and communications technologies. The technologies must be carefully selected and the applications designed to achieve the business needs required from the overall organizational information system. The MOBILE framework can assist information technology professionals in determining the applicability of mobile technology to an organizational problem, opportunity, or directive. Mobile computing is a versatile and potentially strategic technology that improves information quality and accessibility, increases operational efficiency, and enhances management effectiveness.
The MOBILE framework is used to determine when it is most appropriate to use mobile computing technology to address a problem, opportunity, or directive. The name MOBILE is derived from the first letter in each of the six categories that make up the framework.
The six categories are:
The six categories are:
M the need for mobility
O the need to improve operations
B the need to break business barriers
I the need to improve information quality
L the need to decrease transaction lag
E the need to improve efficiency
TECHNOLOGY WILL CHANGE
NEW TECHNOLOGIES:
Exciting new technologies are being developed that will drastically alter and improve mobile computing capabilities. Two of these technologies are low earth orbit (LEO) satellites and wearable computers. Current LEO satellite developments promise ubiquitous and high-speed network access using extremely small and low power devices. Soon, it will be possible and economical to provide all mobile workers with a connected mode for all mobile computing operations. Advances in microcomputer, display, and natural interface technologies are making the first wave of commercially useful wearable computers possible. These devices are still in the experimental stages, and are not commonplace, but are finding applications in areas like aircraft inspection; where a hands-free operating environment and access to large amounts of information is required. In the future, wearable computers are predicted to replace the myriad of personal electronic devices (computers, cell phone, pagers, tape recorders, and cameras) with an integrated and unobtrusive wearable replacement that merges the user's work space with his or her information space. (Mann, 1998) (Jastrzembski, 1997) The ways in which these types of technologies can be applied to solve problems is only limited by the creativity and skill of the developers.
ADAPTING TO CHANGE
The field of mobile computing is still evolving. Even more advanced and yet unimagined mobile technologies will certainly be discovered. Many of the advances will be evolutionary, but some will be revolutionary. The key to integrating these new technologies into the organizational information system will be forward thinking, adaptability, life-long learning, technical competence, an explorative spirit, and the use of tools such as the MOBILE framework. The result will be hardware, software, and communications systems that are even more mobile and more capable of accomplishing organizational objectives.
CONCLUSION:
Mobile computing offers significant benefits for organizations that choose to integrate the technology into their fixed organizational information system. Mobile computing is made possible by portable computer hardware, software, and communications systems that interact with a non-mobile organizational information system while away from the normal, fixed workplace.
Mobile computing is a versatile and potentially strategic technology that improves information quality and accessibility, increases operational efficiency, and enhances management effectiveness. A detailed analysis, supported by selective presentation of published literature, is used to elucidate and support these asserted benefits of mobile computing. Additionally, a set of heuristics called the MOBILE framework is developed. The MOBILE framework assists information technology professionals in achieving the stated benefits of mobile computing by defining the types of problems, opportunities, and directives that are best addressed through mobile computing technology.
REFERENCES:
1.umpcportal.com
2.en.wikipediawiki/
3.Mobile Computing - Tomasz Imielinski, Henry F Korth - 764 pages
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MOBILE COMPUTING
ABSTRACT:
Mobile data communication has become a very important and rapidly evolving technology as it allows users to transmit data from remote locations to other remote or fixed locations. This proves to be the solution to the biggest problem of business people on the move “ mobility.
In this paper we give an overview of existing cellular networks and describe in brief the CDPD technology which allows data communications across these networks. Finally, we look at the applications of Mobile Computing in the real world

Presented by:
SUREKHA&SAIRAM
Btech-2nd year C.B.I.T (PRODDATUR)

DEFINITION:
Mobile computing is a generic term describing one's ability to use technology while moving, as opposed to portable computers, which are only practical for use while deployed in a stationary configuration.
Principle:
Mobile voice communication is widely established throughout the world and has had a very rapid increase in the number of subscribers to the various cellular networks over the last few years. An extension of this technology is the ability to send and receive data across these cellular networks. This is the principle of mobile computing.
History:
The fascinating world of mobile computing has only been around since the 1990s. Since then, devices that have been developed for mobile computing have taken over the wireless industry. This new type of communication is a very powerful tool for both businesses and personal use.
Mobile computing has evolved from two-way radios that use large antennas to communicate simple messages to three inch personal computers that can do almost everything a regular computer does. . The first mobile storage systems can be traced back only as far as the advent of the age of electronics.
CONNECTIVITY:
Wi-Fi
Wireless Broadband
Bluetooth
EXISTING CELLULAR NETWORK ARCHITECTURE:
Mobile telephony took off with the introduction of cellular technology which allowed the efficient utilization of frequencies enabling the connection of a large number of users. During the 1980's analogue technology was used. Among the most well known systems were the NMT900 and 450 (Nordic Mobile Telephone) and the AMPS (Advanced Mobile Phone Service). In the 1990's the digital cellular technology was introduced with GSM (Global System Mobile) being the most widely accepted system around the world. Other such systems are the DCS1800 (Digital Communication System) and the PCS1900 (Personal Communication System).
A cellular network consists of mobile units linked together to switching equipment, which interconnect the different parts of the network and allow access to the fixed Public Switched Telephone Network (PSTN). The technology is hidden from view; it's incorporated in a number of transceivers called Base Stations (BS). Every BS is located at a strategically selected place and covers a given area or cell - hence the name cellular communications. A number of adjacent cells grouped together form an area and the corresponding BSâ„¢s communicate through a so called Mobile Switching Centre (MSC). The MSC is the heart of a cellular radio system. It is responsible for routing, or switching, calls from the originator to the destinator. It can be thought of managing the cell, being responsible for set-up, routing control and termination of the call, for management of inter-MSC hand over and supplementary services, and for collecting charging and accounting information. The MSC may be connected to other MSCâ„¢s on the same network or to the PSTN.

Mobile Switching Centre
The frequencies used vary according to the cellular network technology implemented. For GSM, 890 - 915 MHz range is used for transmission and 935 -960 MHz for reception. The DCS technology uses frequencies in the 1800MHz range while PCS in the 1900MHz range.
Each cell has a number of channels associated with it. These are assigned to subscribers on demand. When a Mobile Station (MS) becomes 'active' it registers with the nearest BS. The corresponding MSC stores the information about that MS and its position. This information is used to direct incoming calls to the MS.
If during a call the MS moves to an adjacent cell then a change of frequency will necessarily occur - since adjacent cells never use the same channels. This procedure is called hand over and is the key to Mobile communications. As the MS is approaching the edge of a cell, the BS monitors the decrease in signal power. The strength of the signal is compared with adjacent cells and the call is handed over to the cell with the strongest signal.
During the switch, the line is lost for about 400ms. When the MS is going from one area to another it registers itself to the new MSC. Its location information is updated, thus allowing MSs to be used outside their 'home' areas.
DATA COMMUNICATIONS:
Data Communications is the exchange of data using existing communication networks. The term data covers a wide range of applications including File Transfer (FT), interconnection between Wide-Area-Networks (WAN), facsimile (fax), electronic mail, access to the internet and the World Wide Web (WWW).
Data Communications have been achieved using a variety of networks such as PSTN, leased-lines and more recently ISDN (Integrated Services Data Network) and ATM (Asynchronous Transfer Mode).ATM (Asynchronous Transfer Mode)/Frame Relay. These networks are partly or totally analogue or digital using technologies such as circuit - switching, packet - switching e.t.c.
Circuit switching implies that data from one user (sender) to another (receiver) has to follow a prespecified path. If a page link to be used is busy, the message cannot be redirected, a property which causes many delays.
Packet switching is an attempt to make better utilization of the existing network by splitting the message to be sent into packets. Each packet contains information about the sender, the receiver, the position of the packet in the message as well as part of the actual message. There are many protocols defining the way packets can be send from the sender to the receiver. The most widely used are the Virtual Circuit-Switching system, which implies that packets have to be sent through the same path, and the Datagram system which allows packets to be sent at various paths depending on the network availability. Packet switching requires more equipment at the receiver, where reconstruction of the message will have to be done.
The introduction of mobility in data communications required a move from the Public Switched Data Network (PSDN) to other networks like the ones used by mobile phones. PCSI has come up with an idea called CDPD (Cellular Digital Packet Data) technology which uses the existing mobile network (frequencies used for mobile telephony).
Mobility implemented in data communications has a significant difference compared to voice communications. Mobile phones allow the user to move around and talk at the same time; the loss of the connection for 400ms during the hand over is undetectable by the user. When it comes to data, 400ms is not only detectable but causes huge distortion to the message. Therefore data can be transmitted from a mobile station under the assumption that it remains stable or within the same cell.
CDPD TECHNOLOGY: THE HOT COOKIE
Today, the mobile data communications market is becoming dominated by a technology called CDPD. There are other alternatives to this technology namely Circuit Switched Cellular, Specialized Mobile Radio and Wireless Data Networks. As can be seen from the table below the CDPD technology is much more advantageous than the others.
Cellular Digital Packet Data (CDPD) Circuit Switched Cellular Specialized Mobile Radio (Extended) Proprietary Wireless Data Networks
Speed best best good good
Security best better good better
Ubiquity best best good better
Cost of Service best better better good
Cost of Deployment best best better good
Mobility best good better good
Interoperability best good good better
CDPD's principle lies in the usage of the idle time in between existing voice signals that are being sent across the cellular networks. The major advantage of this system is the fact that the idle time is not chargeable and so the cost of data transmission is very low. This may be regarded as the most important consideration by business individuals.
CDPD networks allow fixed or mobile users to connect to the network across a fixed page link and a packet switched system respectively. Fixed users have a fixed physical page link to the CDPD network. In the case of a mobile end user, the user can, if CDPD network facilities are non-existent, connect to existing circuit switched networks and transmit data via these networks. This is known as Circuit Switched CDPD (CS-CDPD).
Circuit Switched CDPD
Service coverage is a fundamental element of providing effective wireless solutions to users and using this method achieves this objective. Where CDPD is available data is split into packets and a packet switched network protocol is used to transport the packets across the network. This may be of either Datagram or Virtual Circuit Switching form.
The data packets are inserted on momentarily unoccupied voice frequencies during the idle time on the voice signals. CDPD networks have a network hierarchy with each level of the hierarchy doing its own specified tasks.
CDPD Overview
The hierarchy consists of the following levels:
Mobile End User Interface.
Using a single device such as a Personal Digital Assistant or personal computer which have been connected to a Radio Frequency (RF) Modem which is specially adapted with the antennae required to transmit data on the cellular network, the mobile end user can transmit both data and voice signals. Voice signals are transmitted via a mobile phone connected to the RF Modem Unit. RF Modems transfer data in both forward and reverse channels using Gaussian Minimum Shift Keying (MSK) modulation , a modified form of Frequency Shift Keying (FSK) at modulation index of 0.5 .
¢ Mobile Data Base Station (MDBS).
In each cell of the cellular reception area, there is a Mobile Data Base Station (MDBS) which is responsible for detection of idle time in voice channels, for relaying data between the mobile units and the Mobile Data Intermediate Systems (MDIS), sending of packets of data onto the appropriate unoccupied frequencies as well as receiving data packets and passing them to the appropriate Mobile end user within its domain.
¢ Detection of idle time.
This is achieved using a scanning receiver (also known as sniffer) housed in the MDBS. The sniffer detects voice traffic by measuring the signal strength on a specific frequency, hence detecting an idle channel.
Relaying data packets between mobile units and networks.
If the sniffer detects two idle channels then the MDBS establishes two RF air-links between the end user unit and itself. Two channels are required to achieve bidirectional communications. One channel is for forward communication from the MDBS to the mobile units. This channel is unique to each mobile unit and hence contention less. The reverse channels are shared between a number of Mobile units and as a result, two mobile units sharing a reverse page link cannot communicate to each other.
Reverse channels are accessed using a Digital Sense Multiple Access with Collision Detection (DSMA - CD) protocol which is similar to the protocol used in Ethernet communication which utilizes Carrier Sense Multiple Access with Collision Detection (CSMA - CD). This protocol allows the collision of two data packets on a common channel to be detected so that the Mobile unit can be alerted by the MDBS to retry transmission at a later time.
Once a page link is established, the MDBS can quickly detect if and when a voice signal is ramping up (requesting) this page link and within the 40ms it takes for the voice signal to ramp up and get a link, the MDBS disconnects from the current air-link and finds another idle channel establishing a new link. This is known as channel hopping.
The speed at which the MDBS hops channels ensures that the CDPD network is completely invisible to the existing cellular networks and it doesn't interfere with transmission of existing voice channels.
When the situation occurs that all voice channels are at capacity, then extra frequencies specifically set aside for CDPD data can be utilized. Although this scenario is very unlikely as each cell within the reception area has typically 57 channels, each of which has an average of 25 - 30% of idle time.
Mobile Data Intermediate Systems (MDIS)
Groups of MDBS that control each cell in the cellular network reception area are connected to a higher level entity in the network hierarchy, the Mobile Data Intermediate Systems. Connection is made via a wideband trunk cable. Data packets are then relayed by MDBS to and from mobile end users and MDIS.
These MDIS use a Mobile Network Location Protocol (MNLP) to exchange location information about Mobile end users within their domain. The MDIS maintains a database for each of the M-ES in its serving area. Each mobile unit has a fixed home area but may be located in any area where reception is available. So, if a MDIS unit receives a data packet addressed to a mobile unit that resides in its domain, it sends the data packet to the appropriate MDBS in its domain which will forward it as required. If the data packet is addressed to a mobile unit in another group of cells, then the MDIS forwards the data packet to the appropriate MDIS using the forward channel. The MDIS units hide all mobility issues from systems in higher levels of the network hierarchy.
In the reverse direction, where messages are from the Mobile end user, packets are routed directly to their destination and not necessarily through the mobile end users home MDIS.
¢ Intermediate Systems (IS)
MDIS are interconnected to these IS which form the backbone of the CDPD system. These systems are unaware of mobility of end-users, as this is hidden by lower levels of the network hierarchy. The ISs are the systems that provide the CDPD interface to the various computer and phone networks.
The IS's relay data between MDIS's and other IS's throughout the network. They can be connected to routers that support Internet and Open Systems Interconnection Connectionless Network Services (OSI-CLNS), to allow access to other cellular carriers and external land- based networks.
CDPD Network
________________________________________
CDPD NETWORK RELIABILITY
There are some actions that are necessary in order to obtain reliability over a network.
¢ User Authentication
The procedure which checks if the identity of the subscriber transferred over the radio path corresponds with the details held in the network.
¢ User Anonymity
Instead of the actual directory telephone number, the International Mobile Subscriber Identity (IMSI) number is used within the network to uniquely identify a mobile subscriber.
¢ Fraud Prevention
Protection against impersonation of authorized users and fraudulent use of the network is required.
¢ Protection of user data
All the signals within the network are encrypted and the identification key is never transmitted through the air. This ensures maximum network and data security.
The information needed for the above actions are stored in data bases. The Home Location Register (HLR) stores information relating the Mobile Station (MS) to its network. This includes information for each MS on subscription levels , supplementary services and the current or most recently used network and location area. The Authentication Centre (AUC) provides the information to authenticate MSs using the network , in order to guard against possible fraud , stolen subscriber cards , or unpaid bills. The Visitor Location Register (VLR) stores information about subscription levels , supplementary services and location for a subscriber who is currently in, or has very recently been ,in that area. It may also record whether a subscriber is currently active, thus avoiding delay and unnecessary use of the network in trying to call a switched off terminal.
The data packets are transmitted at speeds of typically 19.2 Kilobits/second to the MDBS, but actual throughput may be as low as 9.6 Kilobits/second due to the extra redundant data that is added to transmitted packets. This information includes sender address, receiver address and in the case of Datagram Switching, a packet ordering number. Check data is also added to allow error correction if bits are incorrectly received. Each data packet is encoded with the check data using a Reed-Solomon forward error correction code. The encoded sequence is then logically OR'ed with a pseudo-random sequence, to assist the MDBS and mobile units in synchronization of bits. The transmitted data is also encrypted to maintain system security.
CDPD follows the OSI standard model for packet switched data communications. The CDPD architecture extends across layers one, two and three of the OSI layer model. The mobile end users handle the layer 4 functions (transport) and higher layers of the OSI model such as user interface.
APPLICATIONS OF MOBILE COMPUTING:
The question that always arises when a business is thinking of buying a mobile computer is "Will it be worth it"
In many fields of work, the ability to keep on the move is vital in order to utilize time efficiently. Efficient utilization of resources (ie: staff) can mean substantial savings in transportation costs and other non quantifiable costs such as increased customer attention, impact of onsite maintenance and improved intercommunication within the business.
The importance of Mobile Computers has been highlighted in many fields of which a few are described below:
¢ Emergency Services
Ability to receive information on the move is vital where the emergency services are involved. Information regarding the address, type and other details of an incident can be dispatched quickly, via a CDPD system using mobile computers, to one or several appropriate mobile units which are in the vicinity of the incident.
Here the reliability and security implemented in the CDPD system would be of great advantage.
Police Incident Information Screen
¢ In companies
Managers can use mobile computers in, say, and critical presentations to major customers. They can access the latest market share information. At a small recess, they can revise the presentation to take advantage of this information. They can communicate with the office about possible new offers and call meetings for discussing responds to the new proposals. Therefore, mobile computers can leverage competitive advantages.
¢ Stock Information Collation/Control
In environments where access to stock is very limited ie: factory warehouses. The use of small portable electronic databases accessed via a mobile computer would be ideal.
Data collated could be directly written to a central database, via a CDPD network, which holds all stock information hence the need for transfer of data to the central computer at a later date is not necessary. This ensures that from the time that a stock count is completed, there is no inconsistency between the data input on the portable computers and the central database.
¢ Credit Card Verification
At Point of Sale (POS) terminals in shops and supermarkets, when customers use credit cards for transactions, the intercommunication required between the bank central computer and the POS terminal, in order to effect verification of the card usage, can take place quickly and securely over cellular channels using a mobile computer unit. This can speed up the transaction process and relieve congestion at the POS terminals.
¢ Electronic Mail/Paging
Usage of a mobile unit to send and read emails is a very useful asset for any business individual, as it allows him/her to keep in touch with any colleagues as well as any urgent developments that may affect their work. Access to the Internet, using mobile computing technology, allows the individual to have vast arrays of knowledge at his/her fingertips.
Paging is also achievable here, giving even more intercommunication capability between individuals, using a single mobile computer device.
THE FUTURE
the future of mobile computing looks increasingly exciting. With the emphasis increasingly on compact, small mobile computers, it may also be possible to have all the practicality of a mobile computer in the size of a hand held organizer or even smaller.
Use of Artificial Intelligence may allow mobile units to be the ultimate in personal secretaries, which can receive emails and paging messages, understand what they are about, and change the individualâ„¢s personal schedule according to the message. This can then be checked by the individual to plan his/her day.
The working lifestyle will change, with the majority of people working from home, rather than commuting. This may be beneficial to the environment as less transportation will be utilized. This mobility aspect may be carried further in that, even in social spheres, people will interact via mobile stations, eliminating the need to venture outside of the house.
This scary concept of a world full of inanimate zombies sitting, locked to their mobile stations, accessing every sphere of their lives via the computer screen becomes ever more real as technology, especially in the field of mobile data communications, rapidly improves and, as shown below, trends are very much towards ubiquitous or mobile computing.
Major Trends in Computing
Indeed, technologies such as Interactive television and Video Image Compression already imply a certain degree of mobility in the home, ie. Home shopping etc. Using the mobile data communication technologies discussed, this mobility may be pushed to extreme.
The future of Mobile Computing is very promising indeed, although technology may go too far, causing detriment to society.
Disadvantages/limitations of mobile computing
¢ Insufficient bandwidth
Mobile internet access is generally slower than direct cable connections, using technologies such as GPRS and EDGE, and more recently 3G networks. These networks are usually available within range of commercial cell phone towers. Higher speed wireless LANs are inexpensive, but have very limited range.
¢ Security standards
When working mobile one is dependent on public networks, requiring careful use of VPNs.
Power consumption
¢ Human interface with devices
¢ Transmission Interferences- weather, distance, etc.
¢ Potential Health Hazards- hospitals
¢ Extensive Wireless Data Plans
¢ Physical Characteristic Limitations- bigger, heavier
¢ Dependence- social consequences
CONCLUSION:
Mobile computing has been applied for various applications. With the rapid technological advancements in Artificial Intelligence, Integrated Circuitry and increases in Computer Processor speeds, the future of mobile computing looks increasingly exciting. The working lifestyle will change, with the majority of people working from home, rather than commuting. This may be beneficial to the environment as less transportation will be utilized.
But, due to in sufficient band width these networks are usually available within range of commercial cell phone towers. Higher speed wireless LANs are inexpensive, but have very limited range.
GLOSSARY
CDPD Cellular Digital Packet Data
NMT Nordic Mobile Telephone
AMPS Advanced Mobile Phone Services
GSM Global System Mobile
DCS Digital Communication System
PCS Personal Communication System
PSTN Public Switched Telephone Network
BS Base Station
MSC Mobile Switching Centre
MS Mobile Station
WAN Wide Area Network
ISDN Integrated Services Data Network
ATM Asynchronous Transfer Mode
PSDN Public Switched Data Network
PCSI Pacific Communication Systems Inc.
CS-CDPD Circuit Switching Cellular Digital Packet Data
RF Radio Frequency
MSK Minimum Shift Keying
FSK Frequency Shift Keying
MDBS Mobile Data Base Station
MDIS Mobile Data Intermediate Systems
DSMA-CD Digital Sense Multiple Access with Collision Detection
CSMA-CD Carrier Sense Multiple Access with Collision Detection
MNLP Mobile Network Location Protocol
M-ES Mobile End Systems
IS Intermediate System
OSI-CLNS Open Systems Interconnection - Connectionless Network Services
IMSI International Mobile Subscriber Identity
HLR Home Location Register
AUC Authentication Centre
VLR Visitor Location Register
POS Point of Sale
REFERENCES:
¢ "Why Mobile Computing Where can it be used" Article by Vasilis Koudounas, 1996.
¢ "CDPD: The answer to all mobile business individuals problems" Article by Omar Iqbal 1996.
¢ "Cellular Digital Packet Data (CDPD): What makes it Reliable" Article by Vasilis Koudounas 1996.
¢ Network Switching Techniques-Circuit, Packet and Datagram: Halsall, Fred. Data Communications, Computer Networks and Open Systems. 4th edition 1996. pp 424-459.
¢ Asynchronous Tranfer Mode , Solution for Broadband ISDN, Third edition 1993, By Martin de Prycker
¢ Communication Systems , Third edition 1994, By Simon Haykin , pp. 511 - 540
Reply
#3
Abstract

This paper introduces Mobile Computing. A technology that allows transmission of data, via a computer, without having to be connected to a fixed physical link. MOBILE computing has become a reality thanks to the convergence of two technologies: the appearance of powerful portable computers and the development of fast reliable networks
The emergence of powerful portable computers, along with advances in wireless communication technologies, has made mobile computing a reality. This paper has produced interesting results in areas such as data dissemination over limited bandwidth channels, location-dependent querying of data, and advanced interfaces for mobile computers, CDPD Technology, and Data Communications.
This paper is an effort to survey the techniques of Mobile Computing based on its mobility and portability and to classify this paper in a few broad areas. This paper will give an overview of existing cellular networks and describe in detail the CDPD technology which allows data communications across these networks and at the applications of Mobile Computing in the real world.
read http://studentbank.in/report-mobile-comp...ull-report
and http://studentbank.in/report-mobile-computing--8900 for getting more information about MOBILE COMPUTING
Reply
#4
[attachment=3423]

ABSTRACT
This paper introduces Mobile Computing. A technology that allows transmission of data, via a computer, without having to be connected to a fixed physical link. MOBILE computing has become a reality thanks to the convergence of two technologies: the appearance of powerful portable computers and the development of fast reliable networks
Definition:
A technology that allows transmission of data, via a computer, without having to be connected to a fixed physical link.
Mobile Voice communication is widely established throughout the world and has had a very rapid increase in the number of subscribers to the various cellular networks over the last few years. An extension of this technology is the ability to send and receive data across these cellular networks. This is the principle of mobile computing.
Mobile data communication has become a very important and rapidly evolving technology as it allows users to transmit data from remote locations to other remote or fixed locations. This proves to be the solution to the biggest problem of business people on the move - mobility.

Natural Evolution of Computing
Mobile Computing & wireless Communications
Wireless Communications Mobility Portability
Quality of connectivity Location transparency Power limitations, storage
Bandwidth limitations Location dependency Display, processing,
Classes of Mobile Devices
Display Only
Info Pad model: limited portable processing
Constrained to operation within prepared infrastructure, like a cordless phone
Advantages w.r.to power consumption, upgrade path, lightweight, impact of lost/broken/stolen device
Laptop Computer
ThinkPad model: portable processing, operates independently of wireless infrastructure
Disadvantages: power consumption, expensive, loss exposure, typically greater than 5 pounds
Personal Digital Assistant
Somewhere between these extremes
Wireless Communications
Harsh communications environment
Lower bandwidth/higher latency (good enough for videoconferencing)
Higher error rates
More frequent disconnection
Performance depends on density of nearby users but inherent scalability of cellular/frequency reuse architecture helps
Connection/Disconnection
Network failure is common
Autonomous operation is highly desirable (Caching is a good idea, e.g., web cache)
Asynchronous/spool-oriented applications, like mail or printing
Disconnected file systems: CODA (CMU), Ficus (UCLA)
Low Bandwidth
Orders of magnitude differences between wide-area, in building wireless
Variable Bandwidth
Applications adaptation to changing quality of connectivity
High bandwidth, low latency: business as usual
High bandwidth, high latency: aggressive prefetching
Low bandwidth, high latency: asynchronous operation.
Wireless Communications Bandwidths and Latencies
EXISTING CELLULAR NETWORK ARCHITECTURE
Mobile telephony took off with the introduction of cellular technology which allowed the efficient utilization of frequencies enabling the connection of a large number of users. During the 1980's analogue technology was used. Among the most well known systems were the NMT900 and 450 (Nordic Mobile Telephone) and the AMPS (Advanced Mobile Phone Service). In the 1990's the digital cellular technology was introduced with GSM (Global System Mobile) being the most widely accepted system around the world. Other such systems are the DCS1800 (Digital Communication System) and the PCS1900 (Personal Communication System).
DATA COMMUNICATIONS
Data Communications is the exchange of data using existing communication networks. The term data covers a wide range of applications including File Transfer (FT), interconnection between Wide-Area-Networks (WAN), facsimile (fax), electronic mail, access to the internet and the World Wide Web (WWW). Data Communications have been achieved using a variety of networks such as PSTN, leased-lines and more recently ISDN (Integrated Services Data Network) and ATM (Asynchronous Transfer Mode)/Frame Relay. These networks are partly or totally analogue or digital using technologies such as circuit - switching, packet - switching e.t.c.
Heterogeneous Wireless Overlay Networks
Mobility
Address Migration
Existing applications send packets to a fixed network address
Need to support dynamically changing local addresses as mobile device moves through network
Mobile IP specification: home environment tracks mobile deviceâ„¢s current location through registration procedure
Route optimization: exploit local caches of <global destination node addresses, current care-of address>
Location updates: (Forwarding, Hierarchical mobility agents)
Mobility: IP Routing
Mobility: Mobile IP
APPLICATIONS OF MOBILE COMPUTING
The question that always arises when a business is thinking of buying a mobile computer is "Will it be worth it?"
In many fields of work, the ability to keep on the move is vital in order to utilize time efficiently. Efficient utilization of resources (i.e.: staff) can mean substantial savings in transportation costs and other non quantifiable costs such as increased customer attention, impact of on site maintenance and improved intercommunication within the business.
The importance of Mobile Computers has been highlighted in many fields of which a few are described below:
Application in Real World
For Estate Agents
Emergency Services
Police Incident Information Screen
In courts
In companies
Stock Information Collation/Control
Credit Card Verification
Taxi/Truck Dispatch
Electronic Mail/Paging
Challenges Of Mobile Computing
Prototyping: In the area of data dissemination, many theoretical studies, simulations, and focused implementations have been tried. However, a full scale prototype that encompasses all of the main ideas is still missing.
Bandwidth utilization: A comprehensive study that analyzes the best way to divide the bandwidth between all the options (data broadcast, indexes, invalidation reports, answers to queries and uplink capacity) is needed.
Transactional properties: More work is needed in studying real cases where transactional properties are needed in mobile applications. Moreover, studying which properties can be effectively relaxed for real applications, as long as effective protocols to enforce the remaining properties is an area that could have a very practical impact in the field.
Optimization of location dependent query processing: Very little has been done in finding ways to obtain quick, and perhaps approximate, answers to these queries.
Data visualization: A key issue is to effectively use the scarce display space in mobile computers to present answers to queries.
9.Mobility and Portability
Mobility
Location Dependent Services
Discovery: What services exist in my local environment? e.g., printers file and compute services, special local applications, etc.
Follow me services: Route calls to my current location, Migrate my workstation desktop to the nearest Workstation screen
Information services:
Broadcast/push information (e.g., Flight 59 will depart from Gate 23)
Pull information (e.g., What gate will Flight 59 depart from?)
Service migration: computations, caches, state, etc. follow mobile device as it moves through the network
Privacy: what applications can track user locations?
Portability
Low Power
Limited compute performance
Low quality displays
Loss of Data
Easily lost
Must be conceived as being network-integrated
Small User Interface
Limited real estate for keyboards
Icon intensive/handwriting/speech
Small Local Storage
Flash memory rather than disk drive

Summary
The Future:
With the rapid technological advancements in Artificial Intelligence, Integrated Circuitry and increases in Computer Processor speeds, the future of mobile computing looks increasingly exciting. With the emphasis increasingly on compact, small mobile computers, it may also be possible to have all the practicality of a mobile computer in the size of a hand held organizer or even smaller.
Use of Artificial Intelligence may allow mobile units to be the ultimate in personal secretaries, which can receive emails and paging messages, understand what they are about, and change the individualâ„¢s personal schedule according to the message.
Indeed, technologies such as Interactive television and Video Image Compression already imply a certain degree of mobility in the home, i.e. Home shopping etc. Using the mobile data communication technologies discussed, this mobility may be pushed to extreme. The future of Mobile Computing is very promising indeed, although technology may go too far, causing detriment to society.
Reply
#5
[attachment=6815]
INTRODUCTION


Mobile computing has been the buzzword for quite a long time. Mobile computing
devices like laptops, webslates & notebook PCs are becoming common
nowadays. The heart of every PC whether a desktop or mobile PC is the
microprocessor. Several microprocessors are available in the market for desktop
PCs from companies like Intel, AMD, Cyrix etc.The mobile computing market has
never had a microprocessor specifically designed for it. The microprocessors used
in mobile PCs are optimized versions of the desktop PC microprocessor. Mobile
computing makes very different demands on processors than desktop computing,
yet up until now, mobile x86 platforms have simply made do with the same old
processors originally designed for desktops. Those processors consume lots of
power, and they get very hot. When you're on the go, a power-hungry processor
means you have to pay a price: run out of power before you've finished, run more
slowly and lose application performance, or run through the airport with pounds of
extra batteries. A hot processor also needs fans to cool it; making the resulting
mobile computer bigger, clunkier and noisier. A newly designed microprocessor
with low power consumption will still be rejected by the market if the performance
is poor. So any attempt in this regard must have a proper 'performance-power'
balance to ensure commercial success. A newly designed microprocessor must be
fully x86 compatible that is they should run x86 applications just like conventional
x86 microprocessors since most of the presently available software’s have been
designed to work on x86 platform.
Reply
#6
presented by:
M. MRUNALINI
M.BHAVANA

[attachment=10090]
ABSTRACT:-
Today’s fast growing world needs faster communication. Technology is making rapid progress and is making many things easier. The innovative idea’s that have been emerged from the tender minds of young scientists led to the evolution of many techniques where our present topic ‘MOBILE COMPUTING’ fits in.
“MOBILE COMPUTING” and COMMUNICATIONS is a major part of wireless communication technology. Mobile computing in means computing done by intermittently connected users who access network resources. It requires a wireless medium such as cellular radio, radio nets and low-orbit satellites. It incorporates wireless adapters using cellular telephone technology to connect portable computers with the cabled network.
Mobile voice communication is widely established throughout the world and had a very rapid increase in the number of subscribers to the various cellular networks over the last few years. An extension of this technology is the ability to send and receive data across these cellular networks. This is the principle of mobile computing.
Mobile data communication has become a very important and rapidly evolving technology as it allows users to transmit data from remote locations to other remote or fixed locations. This proves to be the solution to the biggest problem of business people on the move-mobility. We in this paper describes about the Mobility Services Architecture which supports applications by a middleware stub. Mobile Computing evolved during the last few years as a result of shrinking portables and growing wireless networks. It enlarges the usability of computers, but raises demanding challenges.
The paper describes about the methodology, problems in wireless industry, and how J2SE is used in this technology .The paper concludes with the pros and cons of this mobile computing and its future
INTRODUCTION:-
The most familiar aspect of mobile computing technology is the hand phone. About two decades ago, a hand phone was bulky and was only used for voice communication. It was merely an extension of the fixed line telephony that allowed users to keep in touch with colleagues. Now the hand phone is not only used for voice communication, it is also used to send text and multimedia messages. Future mobile devices will not only enable Internet access, but will also support high-speed data services.
In addition to the hand phone, various types of mobile devices are now available, for example, personal digital assistants (PDAs) and pocket personal computers (PCs). Road warriors use mobile devices to access up-to-date information from the corporate database. A police officer at a crime scene may send a fingerprint picked up there for matching with data in a central database
through a wireless network, hence leading to faster identification and arrest of potential suspects. The global positioning system (GPS) is used in search and rescue missions, for monitoring and preservation of wildlife, and for vehicle theft prevention. Though many of us are unaware of when mobile computing technology is being used, it has permeated all aspects of our lives.
What is mobile computing? Simply defined, it is the use of a wireless network infrastructure to provide anytime, anywhere communications and access to information. There are many aspects of mobile computing and, sometimes, different terms are used to refer to them. This chapter gives an overview of what mobile computing has to offer and how it improves the quality of our lives. Later chapters discuss the underlying wireless networks and technologies that make mobile computing applications possible.
Evolution of Wireless Networks and Services:-
The first generation (1G) wireless network was analog. The first in North America was advanced mobile phone system (AMPS), which was based on frequency division multiple access. A total of 1664 channels were available in the 824 to 849 MHz and 869 to 894 MHz band, providing 832 downlink (DL) and 832 uplink (UL) channels. AMPS, widely used in North America, supports frequency reuse. The underlying network is a cellular network where a geographical region is divided into cells. A base station (BS) at the center of the cell transmits signals to and from users within the cell.
The second generation (2G) systems onward are digital. Digital systems make possible an array of new services such as caller ID. The Global System for Mobile Communications (GSM) is a popular 2G system. GSM offers a data rate of 9.6 to 14.4 kbps. It supports international roaming, which means users may have access to wireless services even when traveling abroad. The most popular service offered by GSM is the Short Message Service (SMS), which allows users to send text messages up to 160 characters long.
2.5G systems support more than just voice communications. In addition to text messaging, 2.5G systems offer a data rate on the order of 100 kbps to support various data technologies, such as Internet access. Most 2.5G systems implement packet switching. The 2.5G systems help provide seamless transition technology between 2G and third generation (3G) systems. The following are 2.5G systems:
High-Speed Circuit-Switched Data (HSCSD): Even though most 2.5G systems implement packet switching, HSCSD continues support for circuit-switched data. It offers a data rate of 115 kbps and is designed to enhance GSM networks. The access technology used is time division multiple access (TDMA). It provides support for Web browsing and file transfers.
General Packet Radio Service (GPRS): GPRS offers a data rate of 168 kbps. It enhances the performance and transmission speeds of GSM. GPRS provides always-on connectivity, whichmeans users do not have to reconnect to the network for each transmission. Because there is a maximum of eight slots to transmit calls on one device, it allows more than one transmission at one time; for example, a voice call and an incoming text message can be handled simultaneously.
Enhanced Data Rates for GSM Evolution (EDGE): EDGE works in conjunction with GPRS and TDMA over GSM networks. Its offered data rate is 384 kbps. EDGE supports data communications while voice communications are supported using the technology on existing networks.
Third-generation (3G) wireless systems are designed to support high bit rate telecommunications. 3G systems are designed to meet the requirements of multimedia applications and Internet services. The bit rate offered ranges from 144 kbps for full mobility applications, 384 kbps for limited mobility applications in macro- and microcellular environments, and 2 Mbps for low-mobility applications in micro- and Pico cellular environments. A very useful service provided by 3G systems is an emergency service with the ability to identify a user's location within 125 m 67% of time. Figure 1.1 shows the evolution of wireless standards
Reply
#7
thnksssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss a lottttttttttttttttttttttttttttttttttttttttttttttttttttttttt
Reply
#8
Thanks for sharing a nice full report of mobile computing. I like it. It is very informative and useful...
Reply
#9
Presented by:
N.Karthik
E.Harika

[attachment=14635]
Mobile computing
Introduction of Mobile Computing
DEFINITION

Mobile computing means different things to different people . The key feature of mobile computing environment is that the user need . It is important for persons who travel away from their primary workplace.
GOAL
The main goal of mobile computing is to work toward true computing freedom from anywhere , anytime and operate as if they were sitting in the “HOME” or “OFFICE”
EXAMPLE
Business professionals are working on a project with colleagues . A short time after making some crucial edits to the new product design , they plugs in the pc , hits a few keys and sends the version.
Reply
#10
to get information about the topic mobile computing full report ,ppt and related topic please refer page link bellow

http://studentbank.in/report-mobile-comp...ull-report

http://studentbank.in/report-mobile-comp...ort?page=2

http://studentbank.in/report-mobile-comp...ars-report

http://studentbank.in/report-mobile-comp...ject-ideas

http://studentbank.in/report-mobile-computing--9850

http://studentbank.in/report-mobile-computing

http://studentbank.in/report-mobile-computing-framework

http://studentbank.in/report-mobile-comp...ull-report

http://studentbank.in/report-mobile-comp...jects-idea

http://studentbank.in/report-mobile-comp...ort?page=2

http://studentbank.in/report-mobile-comp...management

http://studentbank.in/report-mobile-computing-projects

http://studentbank.in/report-mobile-comp...cts-topics

Reply
#11
mobile computing

[attachment=16999]
Introduction
Mobile computing has been given special attention as the next personal computing and communication environment, because of the enormous improvement in performance of the portable computer, personal digital assistant (PDA), and wireless networking infrastructure. However, mobile communication infrastructures, especially wireless data networks, lack communication speed, reliability and security. Mobile users are worried about information leakage by wireless tapping. Therefore, research and development is needed for communication security of mobile computing environments. Encryption tools and new applications that use exclusive API for security control have been proposed. This paper describes a communication method with data compression and encryption for mobile computing environments. This method offers communication, data compression and encryption from end to end by adding a process via WinSock API without changing the existing TCP/IP-based application.
<!--[if !vml]--> <!--[endif]-->
Problems of communication, data compression and encryption processing
There are two methods of compressing and encrypting communication data:

<!--[if !supportLists]-->1. <!--[endif]-->Encryption done by the application and compression done by the modem.
<!--[if !supportLists]-->2. <!--[endif]-->Embedding the functions of encryption and compression into the communication control software.
Both methods have problems. High-performance compression is not anticipated using method 1, because data randomizing by the first encryption process removes regularity, thereby preventing efficient compression in the compression sequence after the encryption sequence. Applications should have the encrypting function in the case of method 1. There is another problem: In method 2, changing the TCP/IP software is necessary, which is against our goal. The method of data compression and encryption processing in PPP (Point to Point Protocol) is popular, but it only takes effect between client and access server.
Data compression and encryption by intercepting WinSock command from WinSock API
WinSock API is a standard application programming interface for TCP/IP-based PC communication programs. We achieved embedded data compression and encryption without changing the TCP/IP and application software by intercepting WinSock commands from WinSock API temporarily and adding individual processing. Figure 2 shows intercepting WinSock commands.
<!--[if !vml]--> <!--[endif]-->
First, our application execution support program changes the linkage between the target application program and WinSock DLL program when the target application program is loaded into memory by the loader before its execution. The secure communication add-in program that we developed intercepts the send command of the application program from WinSock API, compresses its data in the send command, encrypts the data, and then returns this command to WinSock DLL, which is properly transferred. On the other hand, the receive command is intercepted from WinSock API, as with the send command. Also, the secure communication add-in program decrypts the data received from WinSock DLL, decompresses it, and then returns it to the application program, which is properly transferred. Other commands of WinSock are processed in the same way as above. By using this method, we have achieved these features without changing any program or any interfaces.
Reply
#12
to get information about the topic "sms architecture in mobile computing " related topic refer the page link bellow


http://studentbank.in/report-mobile-comp...e=threaded

http://studentbank.in/report-mobile-comp...nar-report

http://studentbank.in/report-mobile-comp...ull-report

http://studentbank.in/report-mobile-comp...?pid=40155
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