100 likes | 194 Views
E N D
1G (or 1-G) refers to the first-generation of wirelesstelephonetechnology, mobiletelecommunications. These are the analog telecommunications standards that were introduced in the 1980s and continued until being replaced by 2Gdigital telecommunications. The main difference between two succeeding mobile telephone systems, 1G and 2G, is that the radio signals that 1G networks use are analog, while 2G networks are digital. Although both systems use digital signaling to connect the radio towers (which listen to the handsets) to the rest of the telephone system, the voice itself during a call is encoded to digital signals in 2G whereas 1G is only modulated to higher frequency, typically 150 MHz and up.
2G (or 2-G) is short for second-generation wirelesstelephonetechnology. Second generation 2G cellular telecom networks were commercially launched on the GSM standard in Finland by Radiolinja (now part of Elisa Oyj) in 1991. Three primary benefits of 2G networks over their predecessors were that phone conversations were digitally encrypted; 2G systems were significantly more efficient on the spectrum allowing for far greater mobile phone penetration levels; and 2G introduced data services for mobile, starting with SMS text messages. After 2G was launched, the previous mobile telephone systems were retrospectively dubbed 1G. While radio signals on 1G networks are analog, radio signals on 2G networks are digital. Both systems use digital signaling to connect the radio towers (which listen to the handsets) to the rest of the telephone system. 2G has been superseded by newer technologies such as 2.5G, 2.75G, 3G, and 4G; however, 2G networks are still used in many parts of the world.
3G networks are expected to provide wireless telecommunications to mobile devices over a wide area, such as mobile phones. These networks are digital and in addition to telephone and video calls they may provide content in a similar format to any other wired internet connection, via TCP/IP protocol. Recent 3G releases, often denoted 3.5G and 3.75G (especially soover the HSPA subfamily and EVDO Rev. B format), also provide mobile broadband access of several Mbit/s to laptop computers and smartphones. 4G mobile technology is the name given to the next generation of mobile devices such as cell phones. It became available from at least one provider in several parts of the US in 2009. There is not yet an agreed industry standard for what constitutes 4G mobile, so for now it is merely a marketing term.
The use of G, standing for generation, in mobile technology covers the major advances of the past 20-30 years. 1G technology involved the first widely available mobile phones. 2G technology, which began in the early 1990s, switched to a digital format and introduced text messaging. 3G technology improved the efficiency of how data is carried, making it possible to carry enhanced information services such as websites in their original format. The latest iPhone is the best known example of 3G technology In telecommunications, 4G is the fourth generation of cellularwireless standards. It is a successor to 3G and 2G families of standards. Speed requirements for 4G service set the peak download speed at 100 Mbit/s for high mobility communication (such as from trains and cars) and 1 Gbit/s for low mobility communication (such as pedestrians and stationary users). A 4G system is expected to provide a comprehensive and secure all-IP based mobile broadband solution to laptop computer wireless modems, smartphones, and other mobile devices. Facilities such as ultra-broadband Internet access, IP telephony, gaming services, and streamed multimedia may be provided to users.
1 G , 2 G , 3 G , 4 G Comparison 1G refers to the first-generation wireless analog technology standards used in mobile telephony. These originated during the 1980s. It basically supported voice calls and sending text messaging services. It was later replaced by 2G or second-generation wireless digital technology. 2G network phones can use various digital protocols such as GSM, CDMA, TDMA, iDEN and PDC. Phones belonging to this technology used narrow band wireless digital network for their operations. As compared to 1G, they also brought more clarity to the conversation. These mobile phones also had a longer battery life, and a semi global roaming facility was available. In between the launch of the 2G and 3G, the 2.5G was introduced as a bridge between the two generations. There were not many critical introductions in this technology, so it was looked upon as a marketing gimmick.
802.11 and 802.11x refers to a family of specifications developed by the IEEE for wireless LAN (WLAN) technology. 802.11 specifies an over-the-air interface between a wireless client and a base station or between two wireless clients. The IEEE accepted the specification in 1997. IEEE - Institute of Electrical and Electronics Engineers, pronounced I-triple-E. Founded in 1884 as the AIEE, the IEEE was formed in 1963 when AIEE merged with IRE. IEEE is an organization composed of engineers, scientists, and students. The IEEE is best known for developing standards for the computer and electronics industry. In particular, the IEEE 802 standards for local-area networks are widely followed. There are several specifications in the 802.11 family: 802.11 — applies to wireless LANs and provides 1 or 2 Mbps transmission in the 2.4 GHz band using either frequency hopping spread spectrum (FHSS) or direct sequence spread spectrum (DSSS). 802.11a — an extension to 802.11 that applies to wireless LANs and provides up to 54-Mbps in the 5GHz band. 802.11a uses an orthogonal frequency division multiplexing encoding scheme rather than FHSS or DSSS.
802.11b (also referred to as 802.11 High Rate or Wi-Fi) — an extension to 802.11 that applies to wireless LANS and provides 11 Mbps transmission (with a fallback to 5.5, 2 and 1-Mbps) in the 2.4 GHz band. 802.11b uses only DSSS. 802.11b was a 1999 ratification to the original 802.11 standard, allowing wireless functionality comparable to Ethernet. 802.11e — a wireless draft standard that defines the Quality of Service (QoS) support for LANs, and is an enhancement to the 802.11a and 802.11b wireless LAN (WLAN) specifications. 802.11e adds QoS features and multimedia support to the existing IEEE 802.11b and IEEE 802.11a wireless standards, while maintaining full backward compatibility with these standards. 802.11g — applies to wireless LANs and is used for transmission over short distances at up to 54-Mbps in the 2.4 GHz bands. 802.11n — 802.11n builds upon previous 802.11 standards by adding multiple-input multiple-output (MIMO). The additional transmitter and receiver antennas allow for increased data throughput through spatial multiplexing and increased range by exploiting the spatial diversity through coding schemes like Alamouti coding. The real speed would be 100 Mbit/s (even 250 Mbit/s in PHY level), and so up to 4-5 times faster than 802.11g. 802.11r - 802.11r, also called Fast Basic Service Set (BSS) Transition, supports VoWi-Fi handoff between access points to enable VoIP roaming on a Wi-Fi network with 802.1X authentication. 802.1X — Not to be confused with 802.11x (which is the term used to describe the family of 802.11 standards) 802.1X is an IEEE standard for port-based Network Access Control that allows network administrators to restricted use of IEEE 802 LAN service access points to secure communication between authenticated and authorized devices.
1 G , 2 G , 3 G , 4 G Comparison Then the 3G or third generation of mobile phone standards and technology made a foray. It is still making its place in the world of today. In this technology, the data is sent through packet switching and voice calls are interpreted through circuit switching. The 3G technologies basically boast of faster data-transmission speeds, greater network capacity and more advanced network services like global roaming. It also incorporated the Wide Band Voice Channel, which enabled two people located in any part of the world to talk and send messages. Some of the other features this technology offers are internet, mobile T.V, video conferencing, video calls, multi media messaging service (MMS), 3D gaming, and multi-gaming. Lastly, we are awaiting the introduction of 4G technology between 2012 and 2015.They are known as the “beyond 3G” or “fourth-generation” cell phone technology. This technology promises a faster rate of data transfer, high-quality multimedia in real-time, multi-media newspapers etc.
IEEE 802.11 is a set of standards for implementing wireless local area network (WLAN) computer communication in the 2.4, 3.6 and 5 GHz frequency bands. They are created and maintained by the IEEELAN/MAN Standards Committee (IEEE 802). The base current version of the standard is IEEE 802.11-2007. The 802.11 family consists of a series of over-the-air modulation techniques that use the same basic protocol. The most popular are those defined by the 802.11b and 802.11g protocols, which are amendments to the original standard. 802.11-1997 was the first wireless networking standard, but 802.11b was the first widely accepted one, followed by 802.11g and 802.11n. Security was originally purposefully weak due to export requirements of some governments, and was later enhanced via the 802.11i amendment after governmental and legislative changes. 802.11n is a new multi-streaming modulation technique. Other standards in the family (c–f, h, j) are service amendments and extensions or corrections to the previous specifications. 802.11b and 802.11g use the 2.4 GHzISM band, operating in the United States under Part 15 of the US Federal Communications Commission Rules and Regulations. Because of this choice of frequency band, 802.11b and g equipment may occasionally suffer interference from microwave ovens, cordless telephones and Bluetooth devices. 802.11b and 802.11g control their interference and susceptibility to interference by using direct-sequence spread spectrum (DSSS) and orthogonal frequency-division multiplexing (OFDM) signaling methods, respectively. 802.11a uses the 5 GHz U-NII band, which, for much of the world, offers at least 23 non-overlapping channels rather than the 2.4 GHz ISM frequency band, where all channels overlap. Better or worse performance with higher or lower frequencies (channels) may be realized, depending on the environment.
The segment of the radio frequency spectrum used by 802.11 varies between countries. In the US, 802.11a and 802.11g devices may be operated without a license, as allowed in Part 15 of the FCC Rules and Regulations. Frequencies used by channels one through six of 802.11b and 802.11g fall within the 2.4 GHz amateur radio band. Licensed amateur radio operators may operate 802.11b/g devices under Part 97 of the FCC Rules and Regulations, allowing increased power output but not commercial content or encryption. History 802.11 technology has its origins in a 1985 ruling by the U.S. Federal Communications Commission that released the ISM band for unlicensed use. In 1991 NCR Corporation/AT&T (now Alcatel-Lucent and LSI Corporation) invented the precursor to 802.11 in Nieuwegein, The Netherlands. The inventors initially intended to use the technology for cashier systems; the first wireless products were brought on the market under the name WaveLAN with raw data rates of 1 Mbit/s and 2 Mbit/s. Vic Hayes, who held the chair of IEEE 802.11 for 10 years and has been called the "father of Wi-Fi" was involved in designing the initial 802.11b and 802.11a standards within the IEEE. In 1992, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) obtained a patent in Australia for a method of wireless data transfer technology based on the use of Fourier transforms to "unsmear" the signal. In 1996, they obtained a patent for the same technology in the US. In April 2009, 14 tech companies selling Wi-Fi devices, including Dell, HP, Microsoft, Intel, Nintendo, and Toshiba, agreed to pay CSIRO $250 million for infringements on the CSIRO patents.