"2.5G"

2.5G, which stands for "second and a half generation," is a cellular wireless technology developed in between its predecessor, 2G, and its successor, 3G.

"2.5G" is an informal term, invented solely for marketing purposes, unlike "2G" or "3G" which are officially defined standards based on those defined by the International Telecommunication (ITU). The term "2.5G" usually describes a 2G cellular system combined with General Packet Radio Services (GPRS), or other services not generally found in 2G or 1G networks.

Wireless telecommunication technology like CDMA200 1x-RTT, Enhanced Data Rates for GSM Evolution (EDGE) or Enhanced General Packet Radio Service (EGPRS), since they have data transmission rates of 144 kbps or higher, may qualify as 3G technology. However, they are usually classified as 2.5G technology because they have slower network speeds than most 3G services.

GPRS is a service commonly associated with 2.5G technology. It has data transmission rates of 28 kbps or higher. GPRS came after the development of the Global System for Mobile (GSM) service, which is classified as 2G technology, and it was succeeded by the development of the Universal Mobile Telecommunication Service (UMTS), which is classified as 3G technology.

A 2.5G system may make use of 2G system infrastructure, but it implements a packet-switched network domain in addition to a circuit-switched domain. This does not necessarily give 2.5G an advantage over 2G in terms of network speed, because bundling of timeslots is also used for circuit-switched data services (HSCSD).

What is 2G Technology | Second Generation Wireless Technology | Digital Radio Signals

2G refers to second generation wireless telecommunication technology. While its predecessor, 1G, made use of analog radio signals, 2G uses digital radio signals.

Based on what type of multiplexing (the process of combining multiple digital data streams into one signal) is employed, 2G technologies may be categorized by whether they are based on time division multiple access (TDMA) or code division multiple access (CDMA).

TDMA-based 2G standards include the following: Global System for Mobile communications (GSM), used worldwide; Integrated Digital Enhanced Network (IDEN), developed by Motorola and used in the United States and Canada; Interim Standard 136 (IS-136) or Digital Advanced Mobile Phone System (D-AMPS), used in North and South America; and Personal Digital Cellular (PDC), used in Japan.
IS-95, on the other hand, is CDMA-based. It was developed by Qualcomm, and is alternately known as TIA-EIA-95 or cdmaOne.

2G makes use of a CODEC (compression-decompression algorithm) to compress and multiplex digital voice data. Through this technology, a 2G network can pack more calls per amount of bandwidth as a 1G network. 2G cellphone units were generally smaller than 1G units, since they emitted less radio power.

Another advantage of 2G over 1G is that the battery life of a 2G handset lasts longer, again due to the lower-powered radio signals. Since it transmitted data through digital signals, 2G also offered additional services such as SMS and e-mail. Its lower power emissions also made 2G handsets safer for consumers to use.

Error checking, a feature allowed by digital voice encoding, improved sound quality by reducing dynamic and lowering the noise floor. Digital voice encoding also made the calls less susceptible to unwanted eavesdropping from third parties, due to the use of radio scanners.

2G, however, does have its disadvantages as well. In comparison to 1G’s analog signals, 2G’s digital signals are very reliant on location and proximity. If a 2G handset made a call far away from a cell tower, the digital signal may not be enough to reach it.

While a call made from a 1G handset had generally poor quality than that of a 2G handset, it survived longer distances. This is due to the analog signal having a smooth curve compared to the digital signal, which had a jagged, angular curve. As conditions worsen, the quality of a call made from a 1G handset would gradually worsen, but a call made from a 2G handset would fail completely.

What is 2G, 3G and 4G?

2G is an acronym for second-generation wireless telephone technology. While its predecessor 1G, made use of analog radio signals, 2G uses digital radio signals. Based on what type of multiplexing (the process of combining multiple digital data streams into one signal) is employed, 2G technologies may be categorized by whether they are based on time division multiple access (TDMA) or code division multiple access (CDMA).

2G makes use of a CODEC (compression-decompression algorithm) to compress and multiplex digital voice data. Through this technology, a 2G network can pack more calls per amount of bandwidth as a 1G network. 2G cellphone units were generally smaller than 1G units, since they emitted less radio power.

The battery life of a 2G handset lasts longer, again due to the lower-powered radio signals.

3G International Mobile Telecommunications-2000 (IMT-2000), better known as 3G or 3rd Generation, is a family of standards for mobile telecommunications fulfilling specifications by the International Telecommunication Union. 3G allows simultaneous use of speech and data services and higher data rates it comes with enhancements over previous wireless technologies, like high-speed transmission, advanced multimedia access and global roaming. 3G helps to simultaneously transfer both voice data (a telephone call) and non-voice data (such as downloading information, exchanging e-mail, and instant messaging.

Features include
1) Several times higher data speed
2) Enhanced audio and video streaming
3) Video-conferencing support
4) Web and WAP browsing at higher speeds
5) IPTV (TV through the Internet) support.

4G 4G refers to the fourth generation of cellular wireless standards successor to 3G and 2G families of standards. A 4G system is expected to provide a comprehensive and secure all-IP based solution where facilities such as IP telephony, ultra-broadband Internet access, gaming services and streamed multimedia may be provided to users.

4G would be offering internet data rates up to what is being called as ‘ultra-broadband’, i.e speed in Gigabytes.

It is expected to use available radio spectrum more efficiently and as a result, provide end users with cable-modem transmission speeds which will support high-quality streaming video.

4G services also have in the offing promises of a minimum of 100 Mbit/s data rate between any two points in the world. Another facility which it will provide is global roaming across multiple networks and interoperability with existing wireless standards.

GSM

GSM is an acronym for ‘Groupe Special Mobile’, which has now been changed to ‘Global System for Mobile Communication’. CDMA refers to ‘Code Division Multiple Access’. The working of GSM and CDMA is very different.

How GSM works.

GSM is a ‘cellular’ technology, that is, the entire coverage area is divided into various hexagonal shaped cells. Every cell has a corresponding network tower, which serves the mobile phones in that cellular area.
That is the entire frequency band is divided into chunks and each such chunk is divided into timeslots and each such portion is made available to a user.

How CDMA works.

In CDMA there are many devices which use the same spread spectrum (hence multiple access). There is one physical channel, and a special code for every device in the coverage network. Using this code, the signal of the device is multiplexed, and the same physical channel is used to send the signal (the codes may or may not change).
That is in simple terms the entire frequency band is available to the user. So, in order to differentiate, the transmission from each user is “spread” or coded using an unique code given to individual user. At the receiving end, the spread
information is decoded.

For comparison, imagine a cocktail party, where couples are talking to each other in a single room. The room represents the available bandwidth. In GSM, a speaker takes turns talking to a listener. The speaker talks for a short time and then stops to let another pair talk. There is never more than one speaker talking in the room, no one has to worry about two conversations mixing. In CDMA, any speaker can talk at any time; however each uses a different language. Each listener can only understand the language of their partner. As more and more couples talk, the background noise gets louder, but because of the difference in languages, conversations do not mix.

General packet radio service

General packet radio service (GPRS) a standard for wireless communications in which a packet oriented mobile data service is available to users of the 2G ,GSM and 3G technology.

GPRS data transfer is typically charged per megabyte of traffic transferred, while data communication via traditional circuit switching is billed per minute of connection time, independent of whether the user actually is using the capacity or is in an idle state.
GPRS, which supports a wide range of bandwidths, is an efficient use of limited bandwidth and is particularly suited for sending and receiving small bursts of data, such as e-mail and Web browsing, as well as large volumes of data.

Services offered
a) Always online
b) Multimedia messaging service (MMS)
c) Push to talk over cellular (PoC/PTT)
d) Internet applications for smart devices through wireless application protocol (WAP)
e) Point-to-point (P2P) service.

Internet Protocol television

IPTV is an acronym for Internet Protocol television through which internet television services are delivered using the architecture and networking methods of the Internet Protocol Suite over a packet-switched network infrastructure, e.g., the Internet and broadband Internet access networks, instead of being delivered through traditional radio frequency broadcast, satellite signal, and cable television (CATV) formats.

In Simple words It is a service where digital cable network is delivered over internet networks rather than on cable or satellite Television.

IPTV services may be classified into three main groups:
a) Live television,
b) Time-shifted programming, and
c) Video on demand.

intel inc

Centrino is a platform-marketing initiative developed by the company Intel. It is a label used for a set of technologies for the central processing unit (CPU), mainboard chipset and wireless network interface, the usage of which, according to Intel, would provide broad wireless network interoperability, better performance and a longer battery life.

The Intel Centrino chips were developed at Intel’s Research and Development (R & D) center located in Haifa, Israel. The Centrino components may be marketed as the hardware within a laptop personal computer. All three Intel-qualified parts must be used in the laptop in order for it to qualify for a Centrino label. Should a laptop only use a Centrino processor and chipset, it qualifies only for the Intel Core label.

As of 2007, Centrino has undergone four successive implementations, with two currently in development.

The first-generation Centrino platform, Carmel, was released in March 2003. The Carmel platform is comprised of the following:

 

Intel Pentium M processor, code-named Banias or Dothan, with a 400 megatransfer per second (MT/s) front side bus (FSB), Socket 478; Intel 855 series chipset, code-named Odem or Montara, DDR-266; and an Intel PRO/Wireless 2100 or later 2200 mini-PCI Wi-Fi adapter, code-named Calexico or Calexico2.

The second-generation Centrino platform, Sonoma, was released in January 2005. The Sonoma platform is comprised of the following:

Pentium M processor, code-named Dothan, with a 533 MT/s FSB, Socket 479; Intel Mobile 915 Express series chipset, code-named Alviso, DDR2-533; and an Intel PRO/Wireless 2200 or 2915ABG mini-PCI Wi-Fi adapter, code-named Calexico2.

The third-generation Centrino platform, Napa, was released in January 2006. The Napa platform is comprised of the following: either an Intel Core Solo, Core Duo processor, code-named Yonah, or an Intel Core 2 Duo processor, code named Merom, with a 667 MT/s FSB Socket M; Intel Mobile 945 Express-series chipset, code-named Calistoga, with ICH7M southbridge; and an Intel PRO/Wireless 3945ABG mini-PCIe Wi-Fi adapter, code-named Golan.

The fourth-generation Centrino platform, Santa Rosa, was released in May 2007. The Santa Rosa platform is comprised of the following:

Intel Core 2 Duo second-generation processor, code-named Merom, with an 800 MT/s FSB, Socket P;
Intel Mobile 965 Express chipset, code-named Crestline, with ICH8M southbridge; and
the Intel Wireless Wi-Fi Link 4965AGN (a/b/g/draft-n) mini-PCIe Wi-Fi adapter (code-named Kedron).

This platform comes with dynamic acceleration technology, enabling faster execution of single-threaded applications. With the enhanced security technologies introduced by Intel with vPro, the platform is branded as "Centrino Pro." Without the enhancements, it is branded as "Centrino Duo."

There are two new platforms currently in development: the Montevina platform, which includes support for WiMAX (802.16), expected to be released in 2008; and the Calpella platform.

Intel has sold over US$5 billion in Centrino hardware since the introduction of Centrino in 2003.

What is GPS

Global Positioning System (GPS), officially named NAVSTAR GPS, is a fully functional Global Navigation Satellite System (GNSS) developed by the United States Department of Defense and accessible as a public good to civilians. It enables a GPS receiver to determine its location, speed, direction of speed, and time, by making use of a constellation of at least 24 medium Earth orbit satellites, managed by the United States Air Force 50th Space Wing, that transmit precise microwave signals. Maintenance of the GPS costs about US$750 million per year.

 

Three components make up the GPS: the space segment (SS), the control segment (CS), and the user segment (US).

The orbiting GPS satellites, also known as Space Vehicles (SV), comprise the SS. There were 24 SVs included in the GPS design, with 4 SVs assigned to each of the six circular orbital planes, each possessing a 55 degree inclination tilt relative to the Earth’s equator, and 60 degrees right ascension of the ascending node separate them. Each SV orbits at an altitude of about 20,200 kilometers and at an orbital radius of 26,000 km twice every sidereal day. Due to the specific arrangement of the orbits, at least six satellites are within line of sight from almost everywhere on the Earth’s surface at any given moment. Additional satellites have been added to provide redundant measurements and in effect, achieve better precision on GPS receiver calculations. There are now 31 SVs present in the SS as of September 2007.

The CS refers to the flight paths of the satellites. They are monitored by National Geospatial-Intelligence Agency (NGA) stations, as well as US Air Force stations in Colorado, Hawaii, Kwajalein, Ascension Island and Diego Garcia. The 2d Space Operations Squadron (2 SOPS) operates the master control station of the US Air Force Space Command, which is located at Schriever Air Force Base in Colorado Springs, Colorado. This station receives the tracking information from all other stations that are monitoring the flight paths.

Every GPS satellite is regularly contacted with a navigational update by 2 SOPS, created by a Kalman filter which uses various inputs such as those from ground monitoring stations and space weather information. The navigational updates are used to synchronize the atomic clocks on board the satellites to within one microsecond, and update the information about the satellites’ location and general system health, also known as almanac and ephemeris data, respectively. This is crucial to the system, because a GPS receiver is able to calculate its position by measuring the distance between itself and three or more GPS satellites, and then using trilateration. The receiver-to-satellite distance is measured by the time delay between transmission and reception of each GPS microwave signal.

The US refers to the GPS receiver of a user, which is composed of: a highly-stable clock, usually a crystal oscillator; an antenna, tuned to the frequencies transmitted by the satellites receiver-processors; and optionally a display for providing location and speed information to the user. Though originally only able to monitor four or five satellites simultaneously, a GPS receiver can now track anywhere between twelve and twenty of them.

The GPS is an important technology for both the military and civilians, making it a dual-use technology. It was originally developed for the military, where it aids in navigation, target tracking, missile and projectile guidance, reconnaissance and map-making, nuclear detonation detection, and search and rescue. For civilians, GPS provides an aid for navigation and land-surveying, and a means of calculating local velocity and orientation. It also serves as a time reference for several applications.

DoCoMo, Inc.,

Nippon Telegraph and Telephone (NTT) DoCoMo, Inc., where "DoCoMo" is shorthand for "Do Communications Over the Mobile Network" as well as a play on "dokomo," the Japanese word for "everywhere," is the most prominent wireless telecommunications operator in Japan, with more than 50 million subscribers.

In August 1991, it was inaugurated as a subsidiary of NTT to take over the mobile phone operations. DoCoMo offers the following services: phone, video phone, i-mode (internet) and mail (i-mode mail, Short Mail, and SMS). Also among the businesses of DoCoMo are paging, satellite, and personal handy-phone system (PHS, under the brand name Paldio).

The company provides Digital Mova, its brand of second generation (2G) personal digital cellular (PDC) services operating in 800 MHz and 1.5 GHz bands with a total of 34 MHz bandwidth, and Freedom of Mobile Multimedia Access (FOMA), DoCoMo’s brand of third generation (3G) wideband code-division multiple access (W-CDMA) services operating in the 2 GHz (1945-1960 MHz) band at a data transmission rate of 384 kbps.

In order to upgrade the data rates towards 14.4 Mbps, DoCoMo is planning to use High-Speed Downlink Packet Access (HSDPA).

DoCoMo has a proprietary mobile internet platform known as i-mode, which as of October 2006 had 47 million customers in Japan alone. It offers mobile phone users the benefits including mobile reservations, secure wireless transactions, updates on the latest information, easy access to thousands of online websites and specialized services such as email, online shopping, mobile banking, restaurant reviews and ticket reservations.

Websites are accessible to mobile users from anywhere in Japan at remarkably inexpensive rates, since charges are based on the volume of data transmitted instead of airtime.

Unlike most mobile operators, DoCoMo dedicates extensive effort to research and development (R & D). Its strong investment in R & D largely helped in allowing DoCoMo to introduce i-mode data services and 3G communications services long before these services were introduced by any other wireless telecommunications company in the world.

Outside of Japan, DoCoMo has a wide range of foreign investments, although the company was not successful in investing in foreign carriers. DoCoMo had invested billions of dollars in Hutchison Telecom, KTF and AT&T Wireless, and subsequently booked a total loss of around US$10 billion, although the operations of DoCoMo in Japan were profitable.

EDGE

EDGE, short for Enhanced Data rates for GSM Evolution, and also known as Enhanced GPRS (EGPRS), is a standard of technology in wireless telecommunications introduced in 2003 that increases data transmission rates and improves data transmission reliability in GSM-enabled mobile phones.

It is usually classified as a second and three-quarters generation (2.75G) technology because although it fits the International Telecommunications Union criteria to qualify as third generation (3G) technology, it runs at a slower network speed (up to 236.8 kbps for 4 timeslots, 473.6 kbps for 8 timeslots).

It is also classified as 2.75G technology because of its variability: EDGE devices have different classes. EDGE devices of Class 3 and below only qualify as second generation (2G), but devices of Class 4 and above qualify as 3G.

EDGE may be used for any packet-switched application, for example, connecting to the internet. The increased data capacity of EDGE makes it important for the use of high-speed data applications such as video services and other multimedia.

Upgrading to EDGE is simple for existing GSM and GPRS networks, as it is a bolt-on enhancement, requires no hardware or software changes to be made in GSM core networks, and is able to function on any network with GPRS deployed on it.

However, EDGE does require some modification to base stations, such as installation of EDGE-compatible transceiver, as well as upgrade of the base station subsystem (BSS) to support EDGE. Upgrading to EDGE also requires new mobile terminal hardware and software for decoding and encoding the new modulation and coding schemes, as well as for carrying higher user data rates in order to implement new services.

EDGE uses nine modulation and coding schemes (MCS). One of these is Gaussian minimum-shift keying (GMSK), and another, used for the upper five MCS, is 8-phase shift keying (8-PSK). In EDGE, a 3-bit word is produced for every change in carrier phase, effectively tripling the gross data rate that GSM provides. Similarly to GPRS, EDGE employs a rate adaptation algorithm that adapts the MCS according to the quality of the radio channel, inclusive of the data transmission’s bit rate and robustness.

Incremental Redundancy is a new technology for EDGE that was not included in GPRS. In this process, redundancy information is sent to be combined in the receiver, rather than retransmitting disturbed packets. The probability of correct decoding is increased as a result of this process.

There is a new technology, EDGE Evolution, that serves as an improvement on EDGE. It features the following enhancements: reduced latency, possibly going down to 100 ms, accomplished by using dual carriers and lowering the Transmission Time Interval from 20 ms to 10 ms; bit rates that are increased up to 1 Mbps peak speed; a higher symbol rate and higher-order modulation, using 32 Quadrature Amplitude Modulation (32QAM) and 16QAM rather than 8-PSK; turbo codes to improve error correction; and better signal quality, achieved through the use of dual antennas.

WAP

WAP, which stands for wireless access point, is a device used for the formation of a wireless network through connection of wireless communication devices. It often connects to a wired network, enabling it to transmit data between wired and wireless devices.

A larger, "roaming"-enabled network may be formed by linking together several WAPs. A WAP is also able to serve as the arbitrator of a network, since it is able to negotiate the durations for which each nearby client device will be able to transmit data over the network. However, this function is generally bypassed, with most IEEE 802.11 networks implementing a distributed pseudo-random algorithm instead.

In the early 2000′s, Wi-Fi WAPs experienced a popularity boost among consumers. This is because of the advantages that having a Wi-Fi WAP offers, such as: low cost; easy installation, as wireless networks do not require having to install cables through walls and ceilings; and mobility, since users are now free to roam, using a device that does not require being cabled to the wall.

There are various ways in using WAPs to form networks. Inside households, there is generally only one WAP, often a wireless router, used to connect all the computers within. For large businesses, several WAPs are usually attached to a wired network to provide wireless access to the local area network (LAN) in the office.

The end user is enabled a full network connection, as well as mobility within the WAP range, so the WAP serves as a gateway, enabling clients to access the wired network. Another way would be to bridge two wired networks using WAPs in conditions that wired networks would be unsuited for.

Another would be to make use of the wireless topology known as a lily-pad network. A lily-pad network is a series of WAPs deployed over a large geographical area, with each WAP connected to a different network in order for multiple networks to be interconnected. As a result, wireless clients can connect to the Internet using hot spots in the network, regardless of which particular network they have attached to for the moment. Clients are able to roam over a large area while staying connected.

The average range of communication of an IEEE 802.11 WAP is a 100 m radius for 30 client devices, although there are a number of variables that affect this, such as indoor or outdoor placement, altitude, power output of the device, signal interference caused by other devices operating on the same frequency, obstructions within the area, weather, antenna type, and operating radio frequency. Repeaters and reflectors, which are able to bounce or amplify radio signals, may be used in order to extend the range of WAPs.

Since wireless networks broadcast messages using radio, a network becomes prone to eavesdropping and unauthorized access to its services by nearby users. As a solution to this problem, wireless traffic encryption schemes have been developed. The first of these, Wired Equivalent Privacy (WEP), had a lot of weaknesses, so new schemes such as Wi-Fi Protected Access (WPA) and the IEEE 802.11i standard (also known as WPA2) were developed. Provided that a strong enough password is used, WPA and WPA2 are both considered secure.

WEP

WEP, which could stand for either Wired Equivalent Privacy or Wireless Encryption Protocol, is a security scheme employed by the Institute of Electrical and Electronics Engineers (IEEE) for IEEE 802.11 wireless networks since the standard’s ratification in September 1999. WEP was part of the IEEE 802.11 standard and its amendments up until IEEE 802.11i, when it was replaced by Wi-Fi Protected Access (WPA) and WPA2.

Wireless networks require more security than wired networks since wireless networks broadcast messages using radio, so they are more prone to eavesdropping. For confidentiality, WEP makes use of the stream cipher RC4, also known as ARCFOUR, and understood to stand for "Rivest Cipher 4" or "Ron’s Code" after the cipher creator, Ron Rivest.

For integrity, it makes use of the Cyclic Redundancy Check 32 (CRC-32) checksum. A 40-bit key, concatenated with a 24-bit initialization vector (IV) to form the RC4 traffic key, is used by standard 64-bit WEP. Key size was limited by U.S. Government export restrictions on cryptographic technology during the period of drafting for the original WEP standard. These limitations on key size were eventually lifted, but by then all of the major computer manufacturers had used a 104-bit key size in their implementations of an extended 128-bit protocol.

Users often enter a 128-bit WEP key as a string of 26 Hexadecimal (Hex) characters, from 0 to 9 and A to F, with each character representing 4 bits of the key. 26 characters with 4 bits each results in a total of 104 bits, which, when added to the 24-bit IV, forms the 128-bit WEP key.

Some vendors provide a 256-bit WEP system, which uses 24 bits for the IV and 232 bits for protection, usually entered as 58 Hexadecimal characters with each character representing 4 bits of the key.

In addition to the government restrictions on key size, another major security limitation in WEP is that interception of more packets is required in cracking a longer key, but there are active attacks that stimulate the necessary traffic. IV collisions and altered packets are also possible weaknesses in WEP, and a longer key only worsens these problems.

WEP features two methods of authentication:

Open System authentication, where it is unnecessary for a WLAN client to provide its credentials to an Access Point during authentication; and

Shared Key authentication, which uses a four-way challenge-response handshake.

Cryptanalysts were able to identify several serious weaknesses in the WEP in the early 2000′s, finding that a WEP connection could easily be cracked with available software in a matter of minutes. This problem was solved by the introduction of a new security scheme, WPA, in 2003, and the IEEE 802.11i standard, which used WPA2, in 2004.

Prior to the inception of WPA and WPA2, however, a number of replacements for WEP had been developed with the goal of restoring security to the wireless network itself. These replacements include: WEP2, which is a stopgap enhancement to WAP that features an enlarged IV value and enforced 128-bit encryption; WEPplus or WEP+, developed by Agere Systems that avoids "weak IVs" to enhance WEP security; and Dynamic WEP, which dynamically changes WEP keys.

WiMAX

WiMAX, which stands for "Worldwide Interoperability for Microwave Access," is a subset of standard, interoperable implementations within the IEEE 802.16 family of standards developed by the Institute of Electrical and Electronics Engineers (IEEE) 802.16 Working Group on Broadband Wireless Access Standards.

WiMAX is the next-generation of wireless technology designed to enable pervasive, high-speed mobile Internet access to the widest array of devices including notebook PCs, handsets, smart phones, and consumer electronics such as gaming devices, cameras, camcorders, music players, and more. As the fourth generation (4G) of wireless technology, WiMAX delivers low-cost, open networks and is the first all IP mobile Internet solution enabling efficient and scalable networks for data, video, and voice. As a major driver in the support and development of WiMAX, Intel has designed embedded WiMAX solutions for a variety of mobile devices supporting the future of high-speed broadband on-the-go.

How does WiMAX Works?  

Think of WiMAX as taking the best part of cellular network access– the part that allows you to easily connect anywhere within your service provider’s wide coverage area and taking the best part of your Wi-Fi experience—the fast speeds and a familiar broadband Internet Experience . And  combining them into a new wireless standard.

WiMAX is a Wide Area Network (WAN) technology. Service providers will deploy a network of towers that will enable access over many miles. Internet access is instantly available anywhere within coverage areas. And like Wi-Fi, WiMAX is a standards-based technology that will unleash the benefits of open markets and global economies of scale to deliver the devices and services that consumers want.

Imagine Broadband on the Go:

Broadband that travels with you across town or across the nation makes all things Internet available on your terms. WiMAX enables the freedom and convenience that comes from having your Internet standing by where and when you need it—staying connected on the go to the people, communities, and resources that make up our lives. Broadband on the go is your front row seat to all the rich multimedia Internet applications you already use, and exciting future possibilities enabled by Mobile WiMAX. •

Playing in Real-Time.:

Play multiplayer 3-D games, view YouTube* videos, listen to radio broadcasts—it’s all there waiting to entertain you on the go.

Working Smarter:

WiMAX pulls productivity out of thin air. Capture lost time by doing things in areas previously unavailable.

Working on the go changes the rules of competition by allowing you to be more productive.

Staying in Touch:

Broadband on the go is about keeping in touch with family, friends, and your communities using all the typical tools like e-mail and IM, but WiMAX adds face-to-face video conferencing and voice to your connections.

Locating People and Places.

WiMAX enables a spontaneous lifestyle. Location-based services creates a new paradigm in accessing real-time information where and when you need it. Mobilizing Your Internet 6.

Receiving TV and Radio on the Go.

There are just more streams of data available with WiMAX, so why not pipe broadcast television and radio into a Mobile WiMAX device? Radio stations already co-broadcast over the Internet. Mobile Internet-based TV transmissions also set the stage for content-on-demand services  like movies and sporting events.

Get Ready for WiMAX:

Major wireless service providers are already planning to roll out WiMAX, and Intel is enabling mass market adoption of WiMAX in notebooks and other mobile Internet devices similar to the way it enabled Wi-Fi in notebooks. WiMAX is a global, standards-based technology that is being adopted and deployed in many countries around the world.

What is WLAN

WLAN, which stands for Wireless Local Area Network, is the technology of networking of a number of computers with each other without requiring the usage of wires. Due to a number of WLAN’s advantages such as ease of installation, convenience, deployment, mobility, expandability, productivity and cost, the popularity of WLAN has increased among home users. Wireless access is now offered as a service, paid or sometimes free, to customers of public businesses such as coffee shops or shopping malls.

Development began in 1970, when a computer communication network using inexpensive ham-like radios called ALOHAnet was created by the University of Hawaii. It features bi-directional star topology, with seven computers deployed over four islands. The central computer, located in Oahu Island, communicated with the other computers without using phone lines.

In 1980, amateur radio operators developed the first generation of wireless data modems. They accomplished this by adding a voice band data communication modem, which had data rates below 9600 bps, to an existing short distance radio system. In 1991, the Institute of Electrical and Electronics Engineers (IEEE) held the first IEEE Workshop on WLAN, with the objective of evaluating alternative technologies. At the same time, the IEEE 802.11 committee was working on developing a standard for WLANs.

 

Orthogonal Frequency Division Multiplexing (OFDM), also known as spread-spectrum modulation technology, is used in WLANs to enable communication between devices in a limited area or basic service set (BSS), which is the set of all stations that can communicate with each other. OFDM is a radio wave-based technology. Through this technology, users are able to move around a broad coverage area while remaining connected to a wireless network.

BSS has two types. Independent BSS contains no access points, meaning that it is an ad-hoc network that is unable to connect with other basic service sets. Unlike Independent BSS, Infrastructure BSS is able to communicate with other stations through access points.

There are three types of WLANs. The first, peer-to-peer (P2P), enables wireless devices to directly communicate with each other without requiring the involvement of central access points. The second WLAN type, which is a bridge, connects networks of different types, such as a wireless network to a wired Ethernet network. The third type is the wireless distribution system, where access points are used as repeaters in place of connecting all access points in a network using wires.

WLAN does have its disadvantages. In terms of security, WLANs are more prone to unwanted eavesdropping by a third party, since WLAN transceivers communicate using radio frequencies. Wireless packets can be intercepted by a nearby computer, and they may be picked up at a distance by a user with a good quality antenna. "Wardrivers" is a term referring to computer users who locate and crack into wireless networks.

WLAN networking signals may be subject to interference and complex propagation effects like multipath or Ricidian fading. WLANs also tend to have a limited range, requiring repeaters or additional access points in order to achieve greater range. They also have a slow data transmission rate of 1 – 108 Mbps, compared to wired networks which can run at rates of 100 Mbps to several Gbps. The built-in congestion avoidance of Transmission Control Protocol (TCP) hindered the transmission speed of wireless networks.

AutoCAD Exercises for Beginners

AutoCAD Exercises for Beginners | AutoCAD Exercises Download | AutoCAD Exercise Workbook | exercises online

AutoCAD Exercises for Beginners | AutoCAD Exercises Download | AutoCAD Exercise Workbook | exercises online


AutoCAD Exercises for Beginners | AutoCAD Exercises Download | AutoCAD Exercise Workbook | exercises online
AutoCAD Exercises for Beginners | AutoCAD Exercises Download | AutoCAD Exercise Workbook | exercises online

CAD Mechanical Drawings Associated with the Design Process | CAD Outsourcing

As a CAD specialist you need to develop standard mechanical engineering drawings such that it can be easily interpreted by the mechanical engineer. Before you start working on mechanical drawings, you must know how to use common mechanical symbols correctly. You have to take special care while relating various mechanical components design drawings to the overall plan of the assembly.

The most important types of CAD mechanical drawings associated with the design process are:

1. General Arrangement drawings
2. Detail drawings
3. Fabrication drawings
4. Assembly drawings

General Arrangement Drawings:

This kind of engineering drawing provides complete information required to generate layout, transportation and installation drawings for the mechanical component. It also includes a list of arrangement drawings which contains all the dimensions, equipment weight, installation details & service delivery details.

Detail Drawings:

All individual members of mechanical equipment need to be depicted in detail to make sure that they are fabricated in accordance with the design requirements, standards and codes. These drawings contain surface texture, geometry, material, size & geometric tolerances etc. The detail drawing also contains all the necessary information required for procurement, manufacturing and regulatory compliance.

Fabrication Drawings:

Fabrication drawings are virtual assembly drawing which includes a list of parts and materials used to for fabrication. The fabrication drawing sometimes also includes referenced documents for heat treatment and stress relieving requirements, geometric tolerances and final machining details.

Assembly Drawings:

Assembly drawings contains drawings of discrete sub-systems, assembly details of how the components, gearbox drawings, roller drawings and guard system drawings. It will include parts list identifying all of the member details with materials, quantities and supply details.

AutoCAD

AutoCAD was one of the first Computer Aided Design programs to be made available on personal computers. It is built to help people design buildings, products, or public spaces, without having to draw up plans by hand. It was released in 1982 by Autodesk, Inc., and offered a personal solution to software that was before then released only for larger workstations. While CAD programs prior to AutoCAD required massive amounts of computing power in the form of gigantic computers, AutoCAD streamlined its operating and optimized it for the IBM PC, allowing people to work from home or on their own work computers.

Through the 1980s, AutoCAD functioned mostly by using simple lines and circles, and text overlays, to set up custom objects. Beginning in the 1990s, AutoCAD began utilizing more robust custom object features, built with an Advanced Programming Interface using C++. And starting in 2007 AutoCAD has had much more advanced 3D tools that allow for greater 3D modeling and exploration of models, with high-quality, fast-moving rendering.

The modern version of AutoCAD allows for much more than simply C++ programming. It has set the standard for operability in terms of Advanced Programming Interfaces in CAD, and can use VBA, .NET, AutoLISP, and Visual LISP, as well as the C++ based ObjectARX. This robust programming set has allowed for great extensibility for AutoCAD, and there are a number of more specific AutoCAD programs, including AutoCAD Electrical, AutoCAD Civil 3D, and AutoCAD Architecture.

The file format that AutoCAD uses, the DWG format, has become a standard for all CAD work. Autodesk shifts its estimates of how many DWG files are in operation in the world, but generally places the number at quite a bit more than one billion. Although a number of other CAD programs exist at this point, including programs for Mac OSX and NIX systems, AutoCAD remains the industry leader and sets a number of standards in the CAD community.

In addition to AutoCAD, Autodesk produces many other design programs, all built to help designers or architects work on specific projects. Their software is focused on all aspects of rendering, both in 2D and 3D, and they consistently seek to push the envelope on what their technologies can achieve. Autodesk software includes industry standards for animation and product design, in addition to AutoCAD itself. For example, files created with their design software may be exported and sent to prototyping facilities, which can input them into 3D printers to generate immediate 3D prototypes for an affordable fee. This seamless interaction between home software and affordable high-speed prototyping is in many ways changing the way design is being undertaken, and has largely removed barriers to entry.

What Is CAD | Computer Aided Design | Draw Technical Drawing And Drafting | 2D & 3D Modeling Program

Computer Aided Design (CAD) is a form of design in which people work with computers to create ideas, models, and prototypes. CAD was originally developed to assist people with technical drawing and drafting, but it has expanded to include numerous other potential uses. A variety of software products designed for CAD can be found on the market, with many being targeted to a specific application or industry.

Drafting and technical drawing can be very painstaking, and they require some special skills. Using CAD for drafting still requires many of the same skills, but by working with a computer instead of on paper, people can be much more efficient. They can also play around with ideas much more easily, moving design elements around and running the design through software programs which can determine whether or not the design is structurally viable. For example, an architect working on a bridge can test the design in simulations to see if it will withstand the load it will need to carry.

CAD can be used to design structures, mechanical components, and molecules, among other things. One advantage of using CAD is that people don’t have to make prototypes to demonstrate a project and its potential, as they can use a three dimensional modeling program to show people how something might look. CAD also allows for endless variations and experiments to show how the look and feel of something can be altered, and these can be done at the click of a button, rather than with painstaking drafting work.

Casual users sometimes like to play with CAD for things like deciding how to organize their furniture, or lay out a garden. They can drag and drop elements and play with the space in a variety of ways, and generate a configuration which will be suitable and aesthetically pleasing. CAD is used by professionals in a number of industries across the manufacturing sector, and it can also appear in some surprising places, like forensics labs, where researchers recreate crime scenes on a computer to explore scenarios.

  

Advanced CAD programs usually require extensive training from their users, as they can be very complex and challenging to work with. More casual programs can be learned in shorter periods of time, with some designed to allow people to work within the program immediately, learning as they go. Simple programs can also sometimes have their functionality increased with expansion packs which are designed to provide additional features, so that people can work within a program they are familiar with when they want to develop more complex designs.