Mobile Computing

Mobile Computing

Mobile computing is human–computer interaction by which a computer is expected to be transported during normal usage. Mobile computing involves mobile communication, mobile hardware, and mobile software. Communication issues include ad hoc and infrastructure networks as well as communication properties, protocols, data formats and concrete technologies. Hardware includes mobile devices or device components. Mobile software deals with the characteristics and requirements of mobile applications.

Mobile Computing is "taking a computer and all necessary files and software out into the field".[1] Mobile computing is any type of computing which use Internet or intranet and respective communications links, as WAN, LAN, WLAN etc. Mobile computers may form a wireless personal network or a piconet.

There are at least three different classes of mobile computing items:

1. portable computers, compacted lightweight units including a full character set keyboard and primarily intended as hosts for software that may be parametrized, as laptops, notebooks, notepads, etc.

2. mobile phones including a restricted key set primarily intended but not restricted to for vocal communications, as cell phones, smart phones, phonepads, etc.

3. wearable computers, mostly limited to functional keys and primarily intended as incorporation of software agents, as watches, wristbands, necklaces, keyless implants, etc.

The existence of these classes is expected to be long lasting, and complementary in personal usage, none replacing one the other in all features of convenience.

History of Wireless Communication

Wireless communication is the transfer of information between two or more points that are not connected by an electrical conductor.

The most common wireless technologies use radio. With radio waves distances can be short, such as a few meters for television or as far as thousands or even millions of kilometers for deep-space radio communications. It encompasses various types of fixed, mobile, and portable applications, including two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of applications of radio wireless technology include GPS units, garage door openers, wireless computer mice, keyboards and headsets, headphones, radio receivers, satellite television, broadcast television and cordless telephones.

Somewhat less common methods of achieving wireless communications includes the use of other electromagnetic wireless technologies, such as light, magnetic, or electric fields or the use of sound.

Photophone

The worlds first wireless telephone conversation occurred in 1880, when Alexander Graham Bell and Charles Sumner Tainter invented and patented the photophone, a telephone that conducted audio conversations wirelessly over modulated light beams (which are narrow projections of electromagnetic waves). In that distant era, when utilities did not yet exist to provide electricity and lasers had not even been imagined in science fiction, there were no practical applications for their invention, which was highly limited by the availability of both sunlight and good weather. Similar to free-space optical communication, the photophone also required a clear line of sight between its transmitter and its receiver. It would be several decades before the photophones principles found their first practical applications in military communications and later in fiber-optic communications.

Early wireless work

David E. Hughes transmitted radio signals over a few hundred yards by means of a clockwork keyed transmitter in 1878.[4] As this was before Maxwells work was understood, Hughes contemporaries dismissed his achievement as mere "Induction". In 1885, Thomas Edison used a vibrator magnet for induction transmission. In 1888, Edison deployed a system of signaling on the Lehigh Valley Railroad. In 1891, Edison obtained the wireless patent for this method using inductance (U.S. Patent 465,971).

In 1888, Heinrich Hertz demonstrated the existence of electromagnetic waves, the underlying basis of most wireless technology. The theory of electromagnetic waves was predicted from the research of James Clerk Maxwell and Michael Faraday. Hertz demonstrated that electromagnetic waves traveled through space in straight lines, could be transmitted, and could be received by an experimental apparatus. Hertz did not follow up on the experiments. Jagadish Chandra Bose around this time developed an early wireless detection device and helped increase the knowledge of millimeter-length electromagnetic waves. Practical applications of wireless radio communication and radio remote control technology were implemented by later inventors.

Radio

The term "wireless" came into public use to refer to a radio receiver or transceiver (a dual purpose receiver and transmitter device), establishing its usage in the field of wireless telegraphy early on; now the term is used to describe modern wireless connections such as in cellular networks and wireless broadband Internet. It is also used in a general sense to refer to any type of operation that is implemented without the use of wires, such as "wireless remote control" or "wireless energy transfer", regardless of the specific technology (e.g. radio, infrared, ultrasonic) used. Guglielmo Marconi and Karl Ferdinand Braun were awarded the 1909 Nobel Prize for Physics for their contribution to wireless telegraphy.

Modes

Radio

radio communication, microwave communication, for example long-range line-of-sight via highly directional antennas, or short-range communication.

Free-space optical

Free-space optical communication (FSO) is an optical communication technology that uses light propagating in free space to wirelessly transmit data for telecommunications or computer networking.

"Free space" means air, outer space, vacuum, or something similar. This contrasts with using solids such as optical fiber cable or an optical transmission line.

The technology is useful where the physical connections are impractical due to high costs or other considerations.

Light, visible and infrared (IR) is used in for example consumer IR devices such as remote controls or via Infrared Data Association (IrDA)

Sonic

Sonic, especially ultrasonic short range communication involves the transmission and reception of sound.

Electromagnetic induction

Electromagnetic induction short range communication and power. This has been used in biomedical situations such as pacemakers, as well as for short-range RFid tags.

Wireless networks

Wireless networking is used to meet many needs. Perhaps the most common use is to connect laptop users who travel from location to location. Another common use is for mobile networks that connect via satellite. A wireless transmission method is a logical choice to network a LAN segment that must frequently change locations. The following situations justify the use of wireless technology:

1. To span a distance beyond the capabilities of typical cabling,

2. To provide a backup communications link in case of normal network failure,

3. To link portable or temporary workstations,

4. To overcome situations where normal cabling is difficult or financially impractical, or

5. To remotely connect mobile users or networks.

Developers need to consider some parameters involving Wireless RF technology for better developing wireless networks:

1. Sub-GHz versus 2.4 GHz frequency trends

2. Operating range and battery life

3. Sensitivity and data rate

4. Network topology and node intelligence

5.Applications may involve point-to-point communication, point-to-multipoint communication, broadcasting, cellular networks and other wireless networks, Wi-Fi technology.

Introduction to wireless Ntworking

Applications of wireless technology

Mobile telephones

One of the best-known examples of wireless technology is the mobile phone, also known as a cellular phone, with more than 4.6 billion mobile cellular subscriptions worldwide as of the end of 2010. These wireless phones use radio waves to enable their users to make phone calls from many locations worldwide. They can be used within range of the mobile telephone site used to house the equipment required to transmit and receive the radio signals from these instruments.

Wireless data communications

Wireless data communications are an essential component of mobile computing. The various available technologies differ in local availability, coverage range and performance, and in some circumstances, users must be able to employ multiple connection types and switch between them. To simplify the experience for the user, connection manager software can be used, or a mobile VPN deployed to handle the multiple connections as a secure, single virtual network. Supporting technologies include:

Wi-Fi is a wireless local area network that enables portable computing devices to connect easily to the Internet. Standardized as IEEE 802.11 a,b,g,n, Wi-Fi approaches speeds of some types of wired Ethernet. Wi-Fi has become the de facto standard for access in private homes, within offices, and at public hotspots. Some businesses charge customers a monthly fee for service, while others have begun offering it for free in an effort to increase the sales of their goods.

Cellular data service offers coverage within a range of 10-15 miles from the nearest cell site. Speeds have increased as technologies have evolved, from earlier technologies such as GSM, CDMA and GPRS, to 3G networks such as W-CDMA, EDGE or CDMA2000.

Mobile Satellite Communications may be used where other wireless connections are unavailable, such as in largely rural areas or remote locations. Satellite communications are especially important for transportation, aviation, maritime and military use.

Wireless Sensor Networks are responsible for sensing noise, interference, and activity in data collection networks. This allows us to detect relevant quantities, monitor and collect data, formulate meaningful user displays, and to perform decision-making functions

Wireless energy transfer

Wireless energy transfer is a process whereby electrical energy is transmitted from a power source to an electrical load that does not have a built-in power source, without the use of interconnecting wires. There are two different fundamental methods for wireless energy transfer. They can be transferred using either far-field methods that involve beam power/lasers, radio or microwave transmissions or near-field using induction. Both methods utilize electromagnetism and magnetic fields.

Wireless Medical Technologies

New technologies such as mobile body area networks (MBAN) the capability to monitor blood pressure, heart rate, oxygen level and body temperature, all with wireless technologies. The MBAN works by sending low powered wireless signals to receivers that feed into nursing stations or monitoring sites. This technology helps with the intentional and unintentional risk of infection or disconnection that arise from wired connections.

Computer interface devices

Answering the call of customers frustrated with cord clutter, many[who?] manufacturers of computer peripherals turned to wireless technology to satisfy their consumer base[citation needed]. Originally these units used bulky, highly limited transceivers to mediate between a computer and a keyboard and mouse; however, more recent generations have used small, high-quality devices, some even incorporating Bluetooth. These systems have become so ubiquitous that some users have begun complaining about a lack of wired peripherals. Wireless devices tend to have a slightly slower response time than their wired counterparts; however, the gap is decreasing.

Computer interface devices such as a keyboard or mouse are powered by a battery and send signals to a receiver through a USB port by way of a radio frequency (RF) receiver. The RF design makes it possible for signals to be transmitted wirelessly and expands the range of effective use, usually up to 10 feet. Distance, physical obstacles, competing signals, and even human bodies can all degrade the signal quality. 

Concerns about the security of wireless keyboards arose at the end of 2007, when it was revealed that Microsofts implementation of encryption in some of its 27 MHz models was highly insecure.

Categories of wireless implementations, devices and standards

1. Radio communication system

2. Broadcasting

3. Amateur radio

4. Land Mobile Radio or Professional Mobile Radio: TETRA, P25, OpenSky, EDACS, DMR, dPMR

5. Cordless telephony:DECT (Digital Enhanced Cordless Telecommunications)

6. Cellular networks: 0G, 1G, 2G, 3G, Beyond 3G (4G), Future wireless

7. List of emerging technologies

8. Short-range point-to-point communication : Wireless microphones, Remote controls, IrDA, RFID (Radio Frequency Identification), TransferJet, Wireless USB, DSRC (Dedicated Short Range Communications), EnOcean, Near Field Communication

9. Wireless sensor networks: ZigBee, EnOcean; Personal area networks, Bluetooth, TransferJet, Ultra-wideband (UWB from WiMedia Alliance).

10. Wireless networks: Wireless LAN (WLAN), (IEEE 802.11 branded as Wi-Fi and HiperLAN), Wireless Metropolitan Area Networks (WMAN) and (LMDS, WiMAX, and HiperMAN)

Evolution of mobile computing

For the past two years, the Ultrabook has played an important role to help reinvigorate innovation in computing. Intel innovation and the introduction of the Ultrabook category has inspired a significant amount of new designs and capabilities. With the introduction of 4th generation Intel Core processors, Intel continues to deliver on the vision for Ultrabook as a multi-year, industry-wide endeavor to a superior computing experience.

The introduction of 4th gen Intel Core ushers in a wave of new Ultrabook "2-in-1" devices that deliver a PC when you need it and a tablet when you want it. Designed specifically for Ultrabook, these new systems represent a giant leap in capabilities by delivering all-day battery life with incredible performance, unprecedented graphics and touch in stunning and unique designs.

Select Ultrabooks powered by 4th generation Intel Core processors will deliver the Intel performance people expect combined with the mobility and responsiveness of a tablet, making them the premium, ultra-versatile 2-in-1 devices. With touch capability and a keyboard, the system adapts to the user and also offers full application compatibility. People can lean forward to work and lean back to relax using just one device.

Designed first and foremost with the Ultrabook in mind and based on the companys flagship 22nm Haswell microarchitecture, the 4th generation Intel Core processors deliver a 50 percent increase in battery life in active workloads over the previous generation. This is the largest generation-over-generation gain in the companys history, equating to over 9 hours of battery life in active workloads for some Ultrabooks based on the new processors.

SOC & AOC Clients
1. Mobile users need solutions that can be used effectively at any time during their work day and used wherever their works takes them.
2. Mobile technology can be implemented with Sometimes On Connectivity/SOC to mobile devices or Always On Connectivity/AOC. 

3. SOC and AOC terminology effectively describe to our clients the communications frequency and performance: capabilities of alternatives for mobile computing solutions. 

4. SOC clients can work effectively in a disconnected mode and take advantage of wireless or wired connections when they are available while AOC clients must be connected all or most of the time to be effective. 

SOC Clients 

1. SOC clients have the ability to store large amounts of data on the mobile device and provide the user with a complete application solution even when the user does not have a wireless or wired data connection.

2. Data updates can occur when wireless, Internet dialup, network or desktop synchronization connections are available. Regardless of connectivity, productive work can proceed. Data updates, when they do occur, can be fast bursts of small amounts of data rather than entire screen images that AOC clients employ. 

3. SOC client technology typically requires a Pocket PC or WinCE device in order to have sufficient processing power and data storage capability. AOC clients have small amounts of data or no data on board the device. 

AOC Clients 

1. AOC clients require a wireless connection that is always on to be able to access data and the user interface, or screen image. 

2. AOC clients typically use a browser for application interactions. Internet-like HTML or WAP is employed by the browser to view web pages that are especially designed for the smaller screens of mobile devices. 

3. AOC clients require transmission of the data and screen image for each user action. Consequently, mobile workers need a wireless connection constantly available in order to effectively use AOC client mobile devices. 

Mobile Technologies

Mobile technology is the technology used for cellular communication. Mobile code division multiple access (CDMA) technology has evolved rapidly over the past few years. Since the start of this millennium, a standard mobile device has gone from being no more than a simple two-way pager to being a mobile phone, GPS navigation device, an embedded web browser and instant messaging client, and a handheld game console. Many experts argue that the future of computer technology rests in mobile computing with wireless networking. Mobile computing by way of tablet computers are becoming more popular. Tablets are available on the 3G and 4G networks.

Bluetooth

Bluetooth is a wireless technology standard for exchanging data over short distances (using short-wavelength UHF radio waves in the ISM band from 2.4 to 2.485 GHz) from fixed and mobile devices, and building personal area networks (PANs). Invented by telecom vendor Ericsson in 1994, it was originally conceived as a wireless alternative to RS-232 data cables. It can connect several devices, overcoming problems of synchronization.

Bluetooth is managed by the Bluetooth Special Interest Group (SIG), which has more than 20,000 member companies in the areas of telecommunication, computing, networking, and consumer electronics. Bluetooth was standardized as IEEE 802.15.1, but the standard is no longer maintained. The SIG oversees the development of the specification, manages the qualification program, and protects the trademarks. To be marketed as a Bluetooth device, it must be qualified to standards defined by the SIG. A network of patents is required to implement the technology, which is licensed only for that qualifying device.

Name and logo

The word "Bluetooth" is an anglicized version of the Scandinavian Blåtand/Blåtann, (Old Norse blát?nn) the epithet of the tenth-century king Harald Bluetooth who united dissonant Danish tribes into a single kingdom, according to a legend, introducing Christianity as well. The idea of this name was proposed in 1997 by Jim Kardach who developed a system that would allow mobile phones to communicate with computers. At the time of this proposal he was reading Frans Gunnar Bengtssons historical novel The Long Ships about Vikings and king Harald Bluetooth. The implication is that Bluetooth does the same with communications protocols, uniting them into one universal standard.

The Bluetooth logo is a bind rune merging the Younger Futhark runes Runic letter ior.svg (Hagall) (?) and Runic letter berkanan.svg (Bjarkan) (?), Haralds initials.

Radio frequency identification(Rfid)

Radio-frequency identification (RFID) is the wireless non-contact use of radio-frequency electromagnetic fields to transfer data, for the purposes of automatically identifying and tracking tags attached to objects. The tags contain electronically stored information. Some tags are powered by and read at short ranges (a few meters) via magnetic fields (electromagnetic induction). Others use a local power source such as a battery, or else have no battery but collect energy from the interrogating EM field, and then act as a passive transponder to emit microwaves or UHF radio waves (i.e., electromagnetic radiation at high frequencies). Battery powered tags may operate at hundreds of meters. Unlike a barcode, the tag does not necessarily need to be within line of sight of the reader, and may be embedded in the tracked object.

Radio frequency identification (RFID) is part of the family of Automatic Identification and Data Capture (AIDC) technologies that includes 1D and 2D bar codes. RFID uses an electronic chip, usually applied to a substrate to form a label, that is affixed to a product, case, pallet or other package. The information it contains may be read, recorded, or rewritten.

RFID tags are used in many industries. An RFID tag attached to an automobile during production can be used to track its progress through the assembly line. Pharmaceuticals can be tracked through warehouses. Livestock and pets may have tags injected, allowing positive identification of the animal.

Since RFID tags can be attached to cash, clothing, everyday possessions, or even implanted within people, the possibility of reading personally-linked information without consent has raised serious privacy concerns.

The RFID tag can be affixed to an object and used to track and manage inventory, assets, people, etc. For example, it can be affixed to cars, computer equipment, books, mobile phones, etc.

RFID offers advantages over manual systems or use of bar codes. The tag can be read if passed near a reader, even if it is covered by the object or not visible. The tag can be read inside a case, carton, box or other container, and unlike barcodes, RFID tags can be read hundreds at a time. Bar codes can only be read one at a time using current devices.

Wireless Broadband

Wireless broadband is technology that provides high-speed wireless Internet access or computer networking access over a wide area.

Originally the word "broadband" had a technical meaning, but became a marketing term for any kind of relatively high-speed computer network or Internet access technology. According to the 802.16-2004 standard, broadband means "having instantaneous bandwidths greater than 1 MHz and supporting data rates greater than about 1.5 Mbit/s."

Mobile wireless broadband

Called mobile broadband, wireless broadband technologies include services from mobile phone service providers such as Verizon Wireless, Sprint Corporation, and AT&T Mobility, which allow a more mobile version of Internet access. Consumers can purchase a PC card, laptop card, or USB equipment to connect their PC or laptop to the Internet via cell phone towers. This type of connection would be stable in almost any area that could also receive a strong cell phone connection. These connections can cost more for portable convenience as well as having speed limitations in all but urban environments.

On June 2, 2010, after months of discussion, AT&T became the first wireless Internet provider in the USA to announce plans to charge according to usage. As the only iPhone service in the United States, AT&T experienced the problem of heavy Internet use more than other providers. About 3 percent of AT&T smart phone customers account for 40 percent of the technologys use. 98 percent of the companys customers use less than 2 gigabytes (4000 page views, 10,000 emails or 200 minutes of streaming video), the limit under the $25 monthly plan, and 65 percent use less than 200 megabytes, the limit for the $15 plan. For each gigabyte in excess of the limit, customers would be charged $10 a month starting June 7, 2010, though existing customers would not be required to change from the $30 a month unlimited service plan. The new plan would become a requirement for those upgrading to the new iPhone technology later in the summer.

TCP connections

The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite (IP), and is so common that the entire suite is often called TCP/IP. TCP provides reliable, ordered and error-checked delivery of a stream of octets between programs running on computers connected to a local area network, intranet or the public Internet. It resides at the transport layer.

Web browsers use TCP when they connect to servers on the World Wide Web, and it is used to deliver email and transfer files from one location to another. HTTP, HTTPS, SMTP, POP3, IMAP, SSH, FTP, Telnet and a variety of other protocols are typically encapsulated in TCP.

Applications that do not require the reliability of a TCP connection may instead use the connectionless User Datagram Protocol (UDP), which emphasizes low-overhead operation and reduced latency rather than error checking and delivery validation.

Network function

The protocol corresponds to the transport layer of TCP/IP suite. TCP provides a communication service at an intermediate level between an application program and the Internet Protocol (IP). That is, when an application program desires to send a large chunk of data across the Internet using IP, instead of breaking the data into IP-sized pieces and issuing a series of IP requests, the software can issue a single request to TCP and let TCP handle the IP details.

IP works by exchanging pieces of information called packets. A packet is a sequence of octets (bytes) and consists of a header followed by a body. The header describes the packets source, destination and control information. The body contains the data IP is transmitting.

Due to network congestion, traffic load balancing, or other unpredictable network behavior, IP packets can be lost, duplicated, or delivered out of order. TCP detects these problems, requests retransmission of lost data, rearranges out-of-order data, and even helps minimize network congestion to reduce the occurrence of the other problems. Once the TCP receiver has reassembled the sequence of octets originally transmitted, it passes them to the receiving application. Thus, TCP abstracts the applications communication from the underlying networking details.

TCP is utilized extensively by many of the Internets most popular applications, including the World Wide Web (WWW), E-mail, File Transfer Protocol, Secure Shell, peer-to-peer file sharing, and some streaming media applications.

TCP is optimized for accurate delivery rather than timely delivery, and therefore, TCP sometimes incurs relatively long delays (on the order of seconds) while waiting for out-of-order messages or retransmissions of lost messages. It is not particularly suitable for real-time applications such as Voice over IP. For such applications, protocols like the Real-time Transport Protocol (RTP) running over the User Datagram Protocol (UDP) are usually recommended instead.

TCP is a reliable stream delivery service that guarantees that all bytes received will be identical with bytes sent and in the correct order. Since packet transfer over many networks is not reliable, a technique known as positive acknowledgment with retransmission is used to guarantee reliability of packet transfers. This fundamental technique requires the receiver to respond with an acknowledgment message as it receives the data. The sender keeps a record of each packet it sends. The sender also maintains a timer from when the packet was sent, and retransmits a packet if the timer expires before the message has been acknowledged. The timer is needed in case a packet gets lost or corrupted.

Snooping TCP

1. The access point snoops into the traffic and buffers packets for fast re-transmission.

2. Transparent extension of TCP within the foreign agent

3. Changes of TCP only within the foreign agent

4. Buffering of packets sent to the mobile host

5. Lost packets on the wireless link (both directions!) will be retransmitted immediately by the mobile host or foreign agent, respectively (so called “local” retransmission)

6. The foreign agent therefore “snoops” the packet flow and recognizes acknowledgements in both directions, it also filters ACKs

7. Data transfer to the mobile host

8. FA buffers data until it receives ACK of the MH, FA detects packet loss via duplicated ACKs or time-out

9. Fast retransmission possible, transparent for the fixed network

10. Data transfer from the mobile host

11. FA detects packet loss on the wireless link via sequence numbers, FA answers directly with a NACK to the MH

12. MH can now retransmit data with only a very short delay

Advantages

1. End-to-end semantics is preserved.

2. Handover is easy. I-TCP requires a careful handover of the system state. Here it falls back to the standard solution if no enhancements.

Problems

1. Snooping TCP does not isolate the wireless link as good as I-TCP

2. Snooping might be useless depending on encryption schemes

3. Data is transmitted twice in case of a paket loss. Once from the FA to the MH and the second time when the ACK finally reaches the CN.

     

IPv6

What is IPv6?

IPv6 is short for "Internet Protocol Version 6". IPv6 is the Internets next-generation protocol, designed to replace the current Internet Protocol, IP Version 4.

In order to communicate over the Internet, computers and other devices must have sender and receiver addresses. These numeric addresses are known as Internet Protocol addresses. As the Internet and the number of people using it grows exponentially, so does the need for IP addresses.

IPv6 is a standard developed by the Internet Engineering Task Force, an organization that develops Internet technologies. The IETF, anticipating the need for more IP addresses, created IPv6 to accommodate the growing number of users and devices accessing the Internet. 

IPv6 allows more users and devices to communicate on the Internet by using bigger numbers to create IP addresses. Under IPv4, every IP address is 32 bits long, which allows 4.3 billion unique addresses. An example IPv4 address is:

172.16.254.1

In comparison, IPv6 addresses are 128 bits, which allow for approximately three hundred and forty trillion, trillion unique IP addresses. An example IPv6 address is:

2001:db8:ffff:1:201:02ff:fe03:0405

IPv6 offers other networking advantages. In most cases, computers and applications will detect and take advantage of IPv6-enabled networks and services without requiring any action from the user. IPv6 also relieves other networking issues that can arise due to the limited number of addresses available on IPv4. For example, IPv6 reduces the need for Network Address Translation, a service that allows multiple clients to share a single IP address, but is not always reliable.

Global system for mobile communication

GSM (Global System for Mobile Communications, originally Groupe Spécial Mobile), is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe protocols for second generation (2G) digital cellular networks used by mobile phones. It is the de facto global standard for mobile communications with over 90% market share, and is available in over 219 countries and territories.

The GSM standard was developed as a replacement for first generation (1G) analog cellular networks, and originally described a digital, circuit-switched network optimized for full duplex voice telephony. This was expanded over time to include data communications, first by circuit-switched transport, then packet data transport via GPRS (General Packet Radio Services) and EDGE (Enhanced Data rates for GSM Evolution or EGPRS).

Subsequently, the 3GPP developed third generation (3G) UMTS standards followed by fourth generation (4G) LTE Advanced standards, which are not part of the ETSI GSM standard.

"GSM" is a trademark owned by the GSM Association. It may also refer to the initially most common voice codec used, Full Rate.

Mobile computing over SMS,SMS

Short Message Service (SMS) is a text messaging service component of phone, Web, or mobile communication systems. It uses standardized communications protocols to allow fixed line or mobile phone devices to exchange short text messages.

SMS was the most widely used data application, with an estimated 3.5 billion active users, or about 80% of all mobile phone subscribers at the end of 2010. The term "SMS" is used for both the user activity and all types of short text messaging in many parts of the world. SMS is also employed in direct marketing, known as SMS marketing.

SMS as used on modern handsets originated from radio telegraphy in radio memo pagers using standardized phone protocols. These were defined in 1985 as part of the Global System for Mobile Communications (GSM) series of standards as a means of sending messages of up to 160 characters to and from GSM mobile handsets. Though most SMS messages are mobile-to-mobile text messages, support for the service has expanded to include other mobile technologies, such as ANSI CDMA networks and Digital AMPS, as well as satellite and landline networks.

General packet radio service(GPRS)

General packet radio service (GPRS) is a packet oriented mobile data service on the 2G and 3G cellular communication systems global system for mobile communications (GSM). GPRS was originally standardized by European Telecommunications Standards Institute (ETSI) in response to the earlier CDPD and i-mode packet-switched cellular technologies. It is now maintained by the 3rd Generation Partnership Project (3GPP).

GPRS usage is typically charged based on volume of data transferred, contrasting with circuit switched data, which is usually billed per minute of connection time. Usage above the bundle cap is either charged per megabyte or disallowed.

GPRS is a best-effort service, implying variable throughput and latency that depend on the number of other users sharing the service concurrently, as opposed to circuit switching, where a certain quality of service (QoS) is guaranteed during the connection. In 2G systems, GPRS provides data rates of 56–114 kbit/second. 2G cellular technology combined with GPRS is sometimes described as 2.5G, that is, a technology between the second (2G) and third (3G) generations of mobile telephony.[4] It provides moderate-speed data transfer, by using unused time division multiple access (TDMA) channels in, for example, the GSM system. GPRS is integrated into GSM Release 97 and newer releases.

The multiple access methods used in GSM with GPRS are based on frequency division duplex (FDD) and TDMA. During a session, a user is assigned to one pair of up-link and down-link frequency channels. This is combined with time domain statistical multiplexing; i.e., packet mode communication, which makes it possible for several users to share the same frequency channel. The packets have constant length, corresponding to a GSM time slot. The down-link uses first-come first-served packet scheduling, while the up-link uses a scheme very similar to reservation ALOHA (R-ALOHA). This means that slotted ALOHA (S-ALOHA) is used for reservation inquiries during a contention phase, and then the actual data is transferred using dynamic TDMA with first-come first-served.

GPRS network architecture

GPRS is a data network that overlays a second-generation GSM network. This data overlay network provides packet data transport at rates from 9.6 to 171 kbps. Additionally, multiple users can share the same air-interface resources simultaneously.

GPRS attempts to reuse the existing GSM network elements as much as possible, but to effectively build a packet-based mobile cellular network, some new network elements, interfaces, and protocols for handling packet traffic are required
.

Applications of GPRS

GPRS enables a variety of new and unique services to the mobile wireless subscriber. These mobile services have unique characteristics that provide enhanced value to customers. These characteristics include the following:

1. Mobility: The ability to maintain constant voice and data communications while on the move.

2. Immediacy: Allows subscribers to obtain connectivity when needed, regardless of location and without a lengthy login session.

3. Localization: Allows subscribers to obtain information relevant to their current location.

The combination of these characteristics provides a wide spectrum of possible applications that can be offered to mobile subscribers. In general, applications can be separated into two high-level categories: corporate and consumer. These include:

1. Communications: E-mail, fax, unified messaging and intranet/Internet access, etc.

2. Value-added services: Information services and games, etc.

3. E-commerce: Retail, ticket purchasing, banking and financial trading, etc.

4. Location-based applications: Navigation, traffic conditions, airline/rail schedules and location finder, etc.

5. Vertical applications: Freight delivery, fleet management and sales-force automation.

6.  Advertising: Advertising may be location sensitive. For example, a user entering a mall can receive advertisements specific to the stores in that mall.

It is also possible to send SMS messages over GPRS. In addition, it is planned to implement supplementary services, such as call forwarding unconditional (CFU), call forwarding on mobile subscriber not reachable (CFNRc), and closed user group (CUG).

Wireless Application Protocol(WAP) WAP,MMS,GPRS application CDMA and 3G

Wireless Application Protocol ( WAP) is a suite of communicaiton protocols for the wireless and mobile devices designed to access the internet independant of manufacturer, vendor, and technology.

The WAP was developed by the WAP Forum, a consortium of device manufacturers, service providers, content providers, and application developers. WAP bridges the gap between the mobile world and the Internet as well as corporate intranets and offers the ability to deliver an unlimited range of mobile value-added services to subscribers—independent of their network, bearer, and terminal. Mobile subscribers can access the same wealth of information from a pocket-sized device as they can from the desktop. WAP is a global standard and is not controlled by any single company. Ericsson, Nokia, Motorola, and Unwired Planet founded the WAP Forum in the summer of 1997 with the initial purpose of defining an industry-wide specification for developing applications over wireless communications networks.

The WAP specifications define a set of protocols in application, session, transaction, security, and transport layers, which enable operators, manufacturers, and applications providers to meet the challenges in advanced wireless service differentiation and fast/flexible service creation. There are now over one hundred members representing terminal and infrastructure manufacturers, operators, carriers, service providers, software houses, content providers, and companies developing services and applications for mobile devices.

The WAP Architecture

There are three major parts of a WAP-enabled system :

1. WAP Gateway

2. HTTP Web Server 

3. WAP Device

WAP Gateway

WAP gateway acts as mediator between Cellular device and HTTP or HTTPS web server. WAP gateway routes requests from the client (Cellular Phones) to an HTTP (or Web) server. The WAP gateway can be located either in a telecom network or in a computer network (an ISP).

The HTTP Web Server

Receive the request from WAP Gateway and process the request and finally sends the output to the WAP Gateway, which in turn the sends this information to the WAP device using its wireless network.

The WAP Device

Wap device (Cellular phones) is part of wireless network. WAP Device sends the WAP request to the WAP Gateway, which in turn translates WAP requests to WWW requests, so the WAP client is able to submit requests to the Web server. After receiving the response from the the HTTP Web Server, WAP Gateway translates Web responses into WAP responses or a format understood by the WAP client and sends it to the WAP Device.

WAP Protocol Stack

For those of you who want to understand the deep down, nitty-gritty of the WAP, heres a quick summary. The WAP relies on stacked architecture, as does Unix, Windows NT, and most other newer technologies. Because wireless devices have limited memory, some layers of the stack have been offloaded to the WAP gateway (which is part of the service providers system). The layers, from top to bottom, are:

1. the application layer, which relies on the Wireless Application Environment (WAE)

2. the session layer, which relies on the Wireless Session Protocol (WSP)

3. the transaction layer, which relies on the Wireless Transaction Protocol (WTP)

4. the security layer, which relies on the Wireless Transport Layer Security (WLTS)

5. the transport layer

6. and the network layer.

WAP Benifits:

Operators: New applications can be introduced quickly and easily without the need for additional infrastructure or modifications to the phone. This will allow operators to differentiate themselves from their competitors with new, customized information services. WAP is an interoperable framework, enabling the provision of end-to-end turnkey solutions that will create a lasting competitive advantage, build consumer loyalty, and increase revenues.

Content Providers : Applications will be written in wireless markup language (WML), which is a subset of extensible markup language (XML). Using the same model as the Internet, WAP will enable content and application developers to grasp the tag-based WML that will pave the way for services to be written and deployed within an operators network quickly and easily. As WAP is a global and interoperable open standard, content providers have immediate access to a wealth of potential customers who will seek such applications to enhance the service offerings given to their own existing and potential subscriber base.

End Users: End users of WAP will benefit from easy, secure access to relevant Internet information and services such as unified messaging, banking, and entertainment through their mobile devices. Intranet information such as corporate databases can also be accessed via WAP technology. Because a wide range of handset manufacturers already supports the WAP initiative, users will have significant freedom of choice when selecting mobile terminals and the applications they support. Users will be able to receive and request information in a controlled, fast, and low-cost environment, a fact that renders WAP services more attractive to consumers who demand more value and functionality from their mobile terminals.

Spread-spectrum Technology

In telecommunication and radio communication, spread-spectrum techniques are methods by which a signal (e.g. an electrical, electromagnetic, or acoustic signal) generated with a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth. These techniques are used for a variety of reasons, including the establishment of secure communications, increasing resistance to natural interference, noise and jamming, to prevent detection, and to limit power flux density (e.g. in satellite downlinks).

Spread-spectrum telecommunications This is a technique in which a telecommunication signal is transmitted on a bandwidth considerably larger than the frequency content of the original information. Frequency hopping is a basic modulation technique used in spread spectrum signal transmission.

Spread-spectrum telecommunications is a signal structuring technique that employs direct sequence, frequency hopping, or a hybrid of these, which can be used for multiple access and/or multiple functions. This technique decreases the potential interference to other receivers while achieving privacy. Spread spectrum generally makes use of a sequential noise-like signal structure to spread the normally narrowband information signal over a relatively wideband (radio) band of frequencies. The receiver correlates the received signals to retrieve the original information signal. Originally there were two motivations: either to resist enemy efforts to jam the communications (anti-jam, or AJ), or to hide the fact that communication was even taking place, sometimes called low probability of intercept (LPI).

Frequency-hopping spread spectrum (FHSS), direct-sequence spread spectrum (DSSS), time-hopping spread spectrum (THSS), chirp spread spectrum (CSS), and combinations of these techniques are forms of spread spectrum. Each of these techniques employs pseudorandom number sequences — created using pseudorandom number generators — to determine and control the spreading pattern of the signal across the allocated bandwidth. Ultra-wideband (UWB) is another modulation technique that accomplishes the same purpose, based on transmitting short duration pulses. Wireless standard IEEE 802.11 uses either FHSS or DSSS in its radio interface.

CDMA versus GSM

GSM and CDMA are competing wireless technologies with GSM enjoying about an 82% market share globally. In the U.S., however, CDMA is the more dominant standard. Technically GSM (Global System for Mobile communications, originally from Groupe Spécial Mobile) is a specification of an entire wireless network infrastructure, while CDMA relates only to the air interface — the radio portion of the technology.

Code division multiple access (CDMA) describes a communication channel access principle that employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code). CDMA also refers to digital cellular telephony systems that use this multiple access scheme, as pioneered by QUALCOMM, and W-CDMA by the International Telecommunication Union (ITU), which is used in GSM’s UMTS.

Comparison chart

third generation networks 

3G, short form of third Generation, is the third generation of mobile telecommunications technology. This is based on a set of standards used for mobile devices and mobile telecommunications use services and networks that comply with the International Mobile Telecommunications-2000 (IMT-2000) specifications by the International Telecommunication Union. 3G finds application in wireless voice telephony, mobile Internet access, fixed wireless Internet access, video calls and mobile TV.

3G telecommunication networks support services that provide an information transfer rate of at least 200 kbit/s. Later 3G releases, often denoted 3.5G and 3.75G, also provide mobile broadband access of several Mbit/s to smartphones and mobile modems in laptop computers. This ensures it can be applied to wireless voice telephony, mobile Internet access, fixed wireless Internet access, video calls and mobile TV technologies.

A new generation of cellular standards has appeared approximately every tenth year since 1G systems were introduced in 1981/1982. Each generation is characterized by new frequency bands, higher data rates and non–backward-compatible transmission technology. The first release of the 3GPP Long Term Evolution (LTE) standard does not completely fulfill the ITU 4G requirements called IMT-Advanced. First release LTE is not backward-compatible with 3G, but is a pre-4G or 3.9G technology,[citation needed] however sometimes branded 4G by the service providers. Its evolution LTE Advanced is a 4G technology. WiMAX is another technology verging on or marketed as 4G.

Applications of 3G

The bandwidth and location information available to 3G devices gives rise to applications not previously available to mobile phone users. Some of the applications are:

Mobile TV

Video on demand

Video Conferencing

Telemedicine

Location-based services

Global Positioning System (GPS)

Evolution

Both 3GPP and 3GPP2 are working on extensions to 3G standard that are based on an all-IP network infrastructure and using advanced wireless technologies such as MIMO. These specifications already display features characteristic for IMT-Advanced (4G), the successor of 3G. However, falling short of the bandwidth requirements for 4G (which is 1 Gbit/s for stationary and 100 Mbit/s for mobile operation), these standards are classified as 3.9G or Pre-4G.

3GPP plans to meet the 4G goals with LTE Advanced, whereas Qualcomm has halted development of UMB in favour of the LTE family.

On 14 December 2009, Telia Sonera announced in an official press release that "We are very proud to be the first operator in the world to offer our customers 4G services." With the launch of their LTE network, initially they are offering pre-4G (or beyond 3G) services in Stockholm, Sweden and Oslo, Norway.

IEEE802.11 standards

IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY) specifications for implementing wireless local area network (WLAN) computer communication in the 2.4, 3.6, 5 and 60 GHz frequency bands. They are created and maintained by the IEEE LAN/MAN Standards Committee (IEEE 802). The base version of the standard was released in 1997 and has had subsequent amendments. The standard and amendments provide the basis for wireless network products using the Wi-Fi brand. While each amendment is officially revoked when it is incorporated in the latest version of the standard, the corporate world tends to market to the revisions because they concisely denote capabilities of their products. As a result, in the market place, each revision tends to become its own standard.

wireless LAN security

Wireless security is the prevention of unauthorized access or damage to computers using wireless networks. The most common types of wireless security are Wired Equivalent Privacy (WEP) and Wi-Fi Protected Access (WPA). WEP is a notoriously weak security standard. The password it uses can often be cracked in a few minutes with a basic laptop computer and widely available software tools. WEP is an old IEEE 802.11 standard from 1999 which was outdated in 2003 by WPA or Wi-Fi Protected Access. WPA was a quick alternative to improve security over WEP. The current standard is WPA2; some hardware cannot support WPA2 without firmware upgrade or replacement. WPA2 uses an encryption device which encrypts the network with a 256 bit key; the longer key length improves security over WEP.

Many laptop computers have wireless cards pre-installed. The ability to enter a network while mobile has great benefits. However, wireless networking is prone to some security issues. Hackers have found wireless networks relatively easy to break into, and even use wireless technology to hack into wired networks. As a result, it is very important that enterprises define effective wireless security policies that guard against unauthorized access to important resources. Wireless Intrusion Prevention Systems (WIPS) or Wireless Intrusion Detection Systems (WIDS) are commonly used to enforce wireless security policies.

The risks to users of wireless technology have increased as the service has become more popular. There were relatively few dangers when wireless technology was first introduced. Hackers had not yet had time to latch on to the new technology and wireless was not commonly found in the work place. However, there are a great number of security risks associated with the current wireless protocols and encryption methods, and in the carelessness and ignorance that exists at the user and corporate IT level. Hacking methods have become much more sophisticated and innovative with wireless. Hacking has also become much easier and more accessible with easy-to-use Windows or Linux-based tools being made available on the web at no charge.

Some organizations that have no wireless access points installed do not feel that they need to address wireless security concerns. In-Stat MDR and META Group have estimated that 95% of all corporate laptop computers that were planned to be purchased in 2005 were equipped with wireless. Issues can arise in a supposedly non-wireless organization when a wireless laptop is plugged into the corporate network. A hacker could sit out in the parking lot and gather info from it through laptops and/or other devices as handhelds, or even break in through this wireless card-equipped laptop and gain access to the wired network.

WiFi v/s 3G

Whats the Difference Between 3G and Wi-Fi?

The Internet can be a confusing thing. Not what’s on it, but how you access it. In my travels I continue to encounter folks who don’t understand the basics of Internet connectivitynamely, the differences between Wi-Fi and 3G.

This can cause problems, especially for buyers of devices like the Kindle Fire and Nook Color, which rely heavily on Internet access.

Indeed, I’ll reckon no small number of these devices get returned because users think they’re brokenwhen what’s really happening is a lack of Wi-Fi.

So let’s talk Internet. If you have broadband (i.e. cable or DSL) service in your home, you probably also have a routera device that makes that broadband connection wireless. In other words, you’ve got Wi-Fi.

That’s great when you’re using your laptop, tablet, iPod Touch, or other device around the house, but what happens when you’re in the car? Or at the beach? No Wi-Fi. And that means no Internet.

That’s where 3G comes in. 3G is kind of like “Wi-Fi everywhere,” meaning it provides Internet access via the same radio towers that provide voice service to your mobile phone. (FYI, 4G is the same thing, just faster.)

Ah, but not all devices are equipped to access 3G service. The Kindle Fire and Nook Color, for example, are Wi-Fi-only tablets. That means they can connect to the Internet only where there’s a Wi-Fi hotspot (which, in addition to your home, can be a coffee shop, library, airport terminal, etc.)

Of course, some laptops, tablets, and gadgets are equipped for 3G as well as Wi-Fi. The catch is that you have to pay extra for the former, usually to a carrier like AT&T or Verizon. Whether or not it’s worth it depends on how much time you out of range of Wi-Fi hotspots. (For example, if you travel a lot.)

That said, I think there’s a smarter option than paying for 3G for a single device: buy a mobile hotspot instead. These pocket-size gizmos connect to 3G (or 4G) networks, then share that connection via Wi-Fi to as many as five nearby devicesnot just one. And the monthly rates are about the same as you’d pay for one gadget with built-in 3G.

Security issues in mobile

1. Where did I leave my phone?: Lookout Labs estimated that a mobile phone was lost in the U.S. every 3.5 seconds in 2011 – and that nearly all who found lost devices tried to access the information on the phone. Now, I hope the “access” was an attempt to determine the owner, but who knows? Even temporarily misplacing a phone can put sensitive data at risk as you have no way of knowing who has the device and the person’s intent. Designing mobile device OS systems and applications with defenses against unauthorized users can go a long way to protecting individuals’ data.

2. Securing files at rest: Encrypting files on mobile devices is a must. After all, who wants sensitive corporate data to end up in the wrong hands? Without the proper encryption, not only are personal documents up for grabs, but also passwords to bank apps, credit card apps, and even business apps. By encrypting sensitive data, one ensures would-be thieves gain a whole lot of nothing.

3. Browsers beware: Mobile users love to browse the web on the go, but did you know this activity opens up phones to serious security risks? The problem is that users cannot see the full URL or link, much less verify whether the link or URL is safe. That means that users could easily browse their way into a phishing-related attack.

4. Update, update, update: People have a tendency to point fingers at mobile device vendors when it comes to security mishaps, but they aren’t always to blame. Updates and patches designed to fix issues in mobile devices are not quite as cut and dry as with PCs. O/S vendors for mobile devices often release updates and patches when users report bugs in the system, but carriers then tend to delay releases that may affect other applications.

5. Layered defenses: The sad truth is that even letting someone borrow one’s mobile device for a few minutes can pose a security risk when multifactor authentication is not implemented. Protecting devices against unauthorized access, not only protects mobile phone users but also companies offering extranet access to their network.

6. Coding that isn’t up to code: Sometimes developers make honest mistakes, inadvertently creating security vulnerabilities via poor coding efforts. Whether failing to implement encrypted channels for data transmission or proper password protection, ineffective development can lead to security weaknesses whether in PCs or mobile phones.

7. Bluetooth benefits: As easy as Bluetooth is to use, it can be just as easy for attackers to gain access to one’s phone and everything stored within. It’s fairly simple for a hacker to run a program to locate available Bluetooth connections and Bingo – they’re in. It’s important to remember to disable the Bluetooth functionality when not in use.

8. Malware on the rise: Malware in mobile devices is serious business and isn’t going away anytime soon, with 2013 projected to be far worse than 2012. Take the Android malware incident in January which impacted more than 600,000 phones, with the malware capable of upgrading itself to expand to other apps. Yet another reminder to the mobile world to only download apps from trusted sources.

security techniques and algorithms