miércoles, 5 de diciembre de 2012

Native IP networks - 4G


By 2009, it had become clear that, at some point, 3G networks would be overwhelmed by the growth of bandwidth-intensive applications like streaming media. Consequently, the industry began looking to data-optimized 4th-generation technologies, with the promise of speed improvements up to 10-fold over existing 3G technologies. The first two commercially available technologies billed as 4G were the WiMAX standard (offered in the U.S. by Sprint) and the LTE standard, first offered in Scandinavia by TeliaSonera.
One of the main ways in which 4G differed technologically from 3G was in its elimination of circuit switching, instead employing an all-IP network. Thus, 4G ushered in a treatment of voice calls just like any other type of streaming audio media, utilizing packet switching over internet, LAN or WAN networks via VoIP.

Mobile broadband data - 3G


                         As the use of 2G phones became more widespread and people began to utilize mobile phones in their daily lives, it became clear that demand for data services (such as access to the internet) was growing. Furthermore, experience from fixed broadband services showed there would also be an ever increasing demand for greater data speeds. The 2G technology was nowhere near up to the job, so the industry began to work on the next generation of technology known as 3G. The main technological difference that distinguishes 3G technology from 2G technology is the use of packet switching rather than circuit switching for data transmission. In addition, the standardization process focused on requirements more than technology (2 Mbit/s maximum data rate indoors, 384 kbit/s outdoors, for example).

                   During the development of 3G systems, 2.5G systems such as CDMA2000 1x and GPRS were developed as extensions to existing 2G networks. These provide some of the features of 3G without fulfilling the promised high data rates or full range of multimedia services. CDMA2000-1X delivers theoretical maximum data speeds of up to 307 kbit/s. Just beyond these is the EDGE system which in theory covers the requirements for 3G system, but is so narrowly above these that any practical system would be sure to fall short.

Digital cellular networks - 2G



In the 1990s, the 'second generation' (2G) mobile phone systems emerged. Two systems competed for supremacy in the global market: the European developed GSM standard and the U.S. developed CDMA standard. These differed from the previous generation by using digital instead of analog transmission, and also fast out-of-band phone-to-network signaling. The rise in mobile phone usage as a result of 2G was explosive and this era also saw theadvent of prepaid mobile phones
In 1991 the first GSM network (Radiolinja) launched in Finland. In general the frequencies used by 2G systems in Europe were higher than those in America, though with some overlap. For example, the 900 MHz frequency range was used for both 1G and 2G systems in Europe, so the 1G systems were rapidly closed down to make space for the 2G systems. In America the IS-54 standard was deployed in the same band as AMPS and displaced some of the existing analog channels.
In 1993, IBM Simon was introduced. This was possibly the world’s first smartphone. It was a mobile phone, pager, fax machine, and PDA all rolled into one. It included a calendar, address book, clock, calculator, notepad, email, and a touchscreen with a QWERTY keyboard.[21] The IBM Simon had a stylus you used to tap the touch screen with. It featured predictive typing that would guess the next characters as you tapped. It had apps, or at least a way to deliver more features by plugging a memory card into the phone.[22]
Coinciding with the introduction of 2G systems was a trend away from the larger "brick" phones toward tiny 100–200g hand-held devices. This change was possible not only through technological improvements such as more advanced batteries and more energy-efficient electronics, but also because of the higher density of cell sites to accommodate increasing usage. The latter meant that the average distance transmission from phone to the base station shortened, leading to increased battery life whilst on the move.
The second generation introduced a new variant of communication called SMS or text messaging. It was initially available only on GSM networks but spread eventually on all digital networks. The first machine-generated SMS message was sent in the UK on 3 December 1992 followed in 1993 by the first person-to-person SMS sent in Finland. The advent of prepaid services in the late 1990s soon made SMS the communication method of choice amongst the young, a trend which spread across all ages.
2G also introduced the ability to access media content on mobile phones. In 1998 the first downloadable content sold to mobile phones was the ring tone, launched by Finland's Radiolinja (now Elisa). Advertising on the mobile phone first appeared in Finland when a free daily SMS news headline service was launched in 2000, sponsored by advertising.
Mobile payments were trialed in 1998 in Finland and Sweden where a mobile phone was used to pay for a Coca Cola vending machine and car parking. Commercial launches followed in 1999 in Norway. The first commercial payment system to mimic banks and credit cards was launched in the Philippines in 1999 simultaneously by mobile operators Globe and Smart.
The first full internet service on mobile phones was introduced by NTT DoCoMo in Japan in 1999.



Analog cellular networks - 1G


The first analog cellular system widely deployed in North America was the Advanced Mobile Phone System (AMPS).[20] It was commercially introduced in the Americas in 1978, Israel in 1986, and Australia in 1987.
AMPS was a pioneering technology that helped drive mass market usage of cellular technology, but it had several serious issues by modern standards. It was unencrypted and easily vulnerable to eavesdropping via a scanner; it was susceptible to cell phone "cloning;" and it used a Frequency-division multiple access (FDMA) scheme and required significant amounts of wireless spectrum to support. Many of the iconic early commercial cell phones such as the Motorola DynaTAC Analog AMPS were eventually superseded by Digital AMPS (D-AMPS) in 1990, and AMPS service was shut down by most North American carriers by 2008.

History of mobile phones


     


The history of mobile phones charts the development of devices which connect wirelessly to the public switched telephone network. The transmission of speech by radio has a long and varied history going back to Reginald Fessenden's invention and shore-to-ship demonstration of radio telephony, through the Second World War with military use of radio telephony links. Hand-held radio transceivershave been available since the 1940s. Mobile telephones for automobiles became available from some telephone companies in the 1940s. Early devices were bulky and consumed high power and the network supported only a few simultaneous conversations. Moderncellular networks allow automatic and pervasive use of mobile phones for voice and data communications.
In the United States, engineers from Bell Labs began work on a system to allow mobile users to place and receive telephone calls from automobiles, leading to the inauguration of mobile service on June 17, 1946 in St. Louis, Missouri. Shortly after, AT&T offered Mobile Telephone Service. A wide range of mostly incompatible mobile telephone services offered limited coverage area and only a few available channels in urban areas. The introduction of cellular technology, which allowed re-use of frequencies many times in small adjacent areas covered by relatively low powered transmitters, made widespread adoption of mobile telephones economically feasible.
The advances in mobile telephony can be traced in successive generations from the early "0G" services like MTS and its successor Improved Mobile Telephone Service, to first generation (1G) analog cellular network, second generation (2G) digital cellular networks, third generation (3G) broadband data services to the current state of the art, fourth generation (4G) native-IP networks.