“4. Nesil GSM Hizmeti” 4G, dördüncü nesil kablosuz telefon teknolojisidir. Diğer GSM standartları gibi hücresel bir ağ sistemi kullanması ve üçüncü nesilde ortaya çıkan kapsama alanı sorunu başta olmak üzere bazı sorunları çözmesi beklenmektedir.
Bağlantı hızı cep telefonlarında 100mps , wi-fi networklerde 1Gbps’dir.
aynı zamanda wimax band genişliği ile aynı boydadır.
4G is an initialism of the term Fourth-Generation Communications System. A 4G system will provide an end-to-end IP solution where voice, data and streamed multimedia can be served to users on an “Anytime, Anywhere” basis at higher data rates than previous generations. No formal definition is set as to what 4G is, but the objectives that are predicted for 4G can be summarized as follows:
4G will be a fully IP-based integrated system of systems and network of networks achieved after the convergence of wired and wireless networks as well as computer, consumer electronics, communication technology, and several other convergences that will be capable of providing 100 Mbit/s and 1 Gbit/s, respectively, in outdoor and indoor environments with end-to-end quality of service and high security, offering any kind of services anytime, anywhere, at affordable cost and one billing.
Hedefler
4G, hizmet kalitesi (HK) ve kablosuz genişband erişimi,Çok ortamlı mesajlaşma hizmeti, video sohbet, taşınabilir TV, yüksek çözünürlüklü TV kapsamı, DVB,
gibi gelecek olan uygulamaların hız gerekliliklerini oturtmak, ses ve veriler gibi minimal hizmet ve “herhangi bir zamanda-herhangi bir yerde” gerçekleşen diğer hizmetler için geliştirilmiştir. 4G çalışma grubu, aşağıda yer alan konuları, 4G kablosuz iletişim standardının hedefleri olarak tanımlamış bulunmaktadır:–Seyyare 12:20, 15 Ekim 2007 (UTC)
- A spectrally efficient system (in bits/s/Hz and bit/s/Hz/site),
- High network capacity: more simultaneous users per cell,
- A nominal data rate of 100 Mbit/s while the client physically moves at high speeds relative to the station, and 1 Gbit/s while client and station are in relatively fixed positions as defined by the ITU-R,
- A data rate of at least 100 Mbit/s between any two points in the world,
- Smooth handoff across heterogeneous networks,
- Seamless connectivity and global roaming across multiple networks,
- High quality of service for next generation multimedia support (real time audio, high speed data, HDTV video content, mobile TV, etc)
- Interoperability with existing wireless standards, and
- An all IP, packet switched network.
In summary, the 4G system should dynamically share and utilise network resources to meet the minimal requirements of all the 4G enabled users.
Kablosuz Sistem Gelişimi
İlk nesil:
Bu nesilden olan sistemlerin hemen hemen hepsi, sesin, esas trafik olduğu düşüncesini taşıyan analog sistemlerdi. Bu sistemler, sık sık, üçüncü şahıslar tarafından, dinlenebilyor idi. Standartlardan bazıları, [NMT]], AMPS, Hicap, CDPD, Mobitex, DataTac dır.
İkinci nesil:
Bu nesile ait olan tüm standartlar, ticari merkezli olup, dijital şekilde idiler. Şu anki pazarın, yaklaşık %60′ına, Avrupa standartları egemen bulunmaktadır. İkinci nesil standartlar, GSM, iDEN, D-AMPS, IS-95, PDC, CSD, PHS, GPRS, HSCSD, ve [[WiDEN] dir.
Üçüncü nesil:
3G, abone sayısında (şebeke kapasitesindki artış) artış gösteren talepleri, yüksek hızda veri iletimi ve çok ortamlı uygulamalar için gerekli olan hızları karşılamak için, değişikliğe başlamıştır. Bu standarttaki sistemler, temel olarak, 2G sistemlerine ait doğrusal bir gelişimdir. Bunlar, bir tanesi, devre anahtarlamalı düğümleri kapsayan ve bir diğeri, paket yönlendirmeli düğümleri kapsayan, iki paralel altyapıya dayandırılmaktadır.
UTB, IMT-2000 ilk adımının bir parçası olarak, üçüncü nesil şeklindeki hava arabirim teknolojilerine ait özel bir seti tanımlamaktadır. Şu an, 2G’den 3G sistemine geçiş olmaktadır. Bu geçişin bir parçası olarak, pek çok teknoloji, standart hale getirilmektedir.
2G’den 3G’ye:2.75G - EDGE]Gelişimi için geliştirilmiş veri hızları |EDGE ve EGPRS, 3G - CDMA 2000,W-CDMA or UMTS (3GSM), FOMA, 1xEV-DO/IS-856, TD-SCDMA, GAN/UMA.
Benzer şekilde, 3G’den 4G’ye: 3.5G - HSDPA, HSUPA, Super3G - HSOPA/UVG
Dördüncü nesil:
4G çalışma gruplarına göre, 4G altyapı ve terminalleri, 2G’den 4G’ye uygulanan, hemen hemen tüm standartlara sahip olacaktır. –Seyyare 12:24, 15 Ekim 2007 (UTC)
Even though the legacy systems are in place to be adopted in 4G for the existing legacy users, going forward the infrastructure will however only be packet based, all-IP. Also, some proposals suggests to have an open platform where the new innovations and evolutions can fit. The technologies which are being called as 4G though not officially are as follows: WiMax, WiBro, 3GPP Long Term Evolution and 3GPP2 Ultra Mobile Broadband.
Components
Access schemes
As the wireless standards evolved, the access techniques used also exhibited increase in efficiency, capacity and scalability. The first generation wireless standards used plain TDMA and FDMA. In the wireless channels, TDMA proved to be less efficient in handling the high data rate channels as it requires large guard periods to alleviate the multipath impact. Similarly, FDMA consumed more bandwidth for guard to avoid inter carrier interference. So in second generation systems, one set of standard used the combination of FDMA and TDMA and the other set introduced a new access scheme called CDMA. Usage of CDMA increased the system capacity and also placed a soft limit on it rather than the hard limit. Date rate is also increased as this access scheme is efficient enough to handle the multipath channel. This enabled the third generation systems to used CDMA as the access scheme IS-2000, UMTS, HSXPA, 1xEV-DO, TD-CDMA and TD-SCDMA. The only issue with the CDMA is that it suffers from poor spectrum flexibility and scalability.
Recently, new access schemes like OFDMA, Single Carrier FDMA, Interleaved FDMA and MC-CDMA are gaining more importance for the next generation systems. WiMax is using OFDMA in the downlink and in the uplink. For the next generation UMTS, OFDMA is considered in the downlink. On the contrary, in the uplink IFDMA is considered since OFDMA contributes more to the PAPR related issues and results in nonlinear operation of amplifiers. IFDMA provides less power fluctuation and thus avoids amplifier issues. Similarly, MC-CDMA is in the proposal for IEEE 802.20 standard. These access schemes offer the same efficiencies as older technologies like CDMA. Apart from that, scalability and higher data rates can be achieved.
The other important advantage of the mentioned access techniques requires less complexity for equalization at the receiver. This is an added advantage especially in the MIMO environments since the spatial multiplexing transmission of MIMO systems inherently requires the high complexity equalization at the receiver.
In addition to improvements in these multiplexing systems, improved modulation techniques are being used. Whereas earlier standards largely used Phase-shift keying, more efficient systems such as 64QAM are being proposed for use with the 3GPP Long Term Evolution standards.
IPv6
Unlike 3G, which is based on two parallel infrastructures consisting of circuit switched and packet switched network nodes respectively, 4G will be based on packet switching only. This will require low-latency data transmission.
It is generally believed that 4th generation wireless networks will support a greater number of wireless devices that are directly addressable and routable. Therefore, in the context of 4G, IPv6 is an important network layer technology and standard that can support a large number of wireless-enabled devices. By increasing the number of IP addresses, IPv6 removes the need for Network Address Translation (NAT), a method of sharing a limited number of addresses among a larger group of devices.
In the context of 4G, IPv6 also enables a number of applications with better multi-cast, security, and route optimization capabilities. With the available address space and number of addressing bits in IPv6, many innovative coding schemes can be developed for 4G devices and applications that could aid deployment of 4G networks and services.
Gelişmiş Anten Sistemleri
Anten iletişimlerindeki performans, kesinlikle, bir anten sistemindeki gelişimlere bağlıdır.
Son zamanlarda, yüksek hız, çok güvenilirlik ve uzun dizi iletişimleri gibi 4G sistemleri hedefini kazanmak için birden fazla organı etkileyen anten teknololojileri ortaya çıkmaktadır. 90′lı yılların başlarında, veri iletişimine ait artan veri hızı ihtiyaçlarını karşılamak için, pek çok iletim programları, önerilmiştir.
Bir teknoloji, [[uzamsal çoklama], bant genişliği korunumu ve güç verimliliği ile önem kazanmıştır. Uzamsal çoklama, verici ve alıcıda, çok çeşitli antenlerin konuşlandırılmasını gerektirmektedir. Ondan sonra, bağımsız akımlar, eşzamanlı olarak, tüm antenlerden iletilebilir. Bu, verilerin hızını, en az sayıdaki alıcı ve verici antenlerle eşit sayıdaki çok değişik katlar içerisinde artırır. Bu, Çoklu -giriş çoklu-çıkış iletişimleri (ÇGÇİ)olarak adlandırılır. Bundan başka, gücünü kaybeden kanallardaki yüksek hızlı verilerin iletimindeki güvenilirlik, verici ya da alıcıda, daha fazla anten kullanılması ile geliştirilebilir. Bu, ilet ya da değişimi al olarak adlandırılmaktadır. –Seyyare 06:17, 17 Ekim 2007 (UTC)
Both transmit/receive diversity and transmit spatial multiplexing are categorized into the space-time coding techniques, which does not necessary require the channel knowledge at the transmit. The other category is closed-loop multiple antenna technologies which use the channel knowledge at the transmitter.
Yazılım tanımlamalı telsiz telefon(YTTT)
[[Yazılım tanımlamalı telsiz telefon|YTTT], açık, kablosuz yapı şekillerinden biridir. 4G, kablosuz standartlar toplamı olduğundan, 4G cihazının, en son hali, çeşitli standartları oluşturacaktır. Bu, telsiz telefon yakınsaması alanı içinde sınıflandırılan YTTT teknolojisi kullanılarak, etkili bir şekilde gerçekleştirilecektir. –Seyyare 12:33, 15 Ekim 2007 (UTC)
Developments
The Japanese company NTT DoCoMo has been testing a 4G communication system prototype with 4×4 MIMO called VSF-OFCDM at 100 Mbit/s while moving, and 1 Gbit/s while stationary. NTT DoCoMo recently reached 5 Gbit/s with 12×12 MIMO while moving at 10 km/h, and is planning on releasing the first commercial network in 2010.
An Irish fixed and wireless broadband company, Digiweb has announced that they have received a mobile communications license from the Irish Telecoms regulator, ComReg. This service will be issued the mobile code 088 in Ireland and will be used for the provision of 4G Mobile communications.Press Release: Digiweb Mobile Takes 088 RTÉ News article: Ireland gets new mobile phone provider
Pervasive networks are an amorphous and presently entirely hypothetical concept where the user can be simultaneously connected to several wireless access technologies and can seamlessly move between them (See handover, IEEE 802.21). These access technologies can be Wi-Fi, UMTS, EDGE, or any other future access technology. Included in this concept is also smart-radio (also known as cognitive radio technology) to efficiently manage spectrum use and transmission power as well as the use of mesh routing protocols to create a pervasive network.
Sprint plans to launch 4G services in trial markets by the end of 2007 with plans to deploy a network that reaches as many as 100 million people in 2008….
The German WiMAX operator Deutsche Breitband Dienste (DBD) has launched WiMAX services (DSLonair) in Magdeburg and Dessau. The subscribers are offered a tariff plan costing 9.95 euros per month offering 2 Mbps download / 300 Kbps upload connection speeds and 1.5 GB monthly traffic. The subscribers are also charged a 16.99 euro one-time fee and 69.90 euro for the equipment and installation. DBD received additional national licenses for WiMAX in December 2006 and have already launched the services in Berlin, Leipzig and Dresden.
American WiMAX services provider Clearwire made its debut on Nasdaq in New York on March 8, 2007. The IPO was underwritten by Merrill Lynch, Morgan Stanley and JP Morgan. Clearwire sold 24 million shares at a price of $25 per share. This adds $600 million in cash to Clearwire, and gives the company a market valuation of just over $3.9 billion.
Uygulamalar
4G’nin en önemli uygulaması net değildir, ama buna rağmen, 4G şebekeleri tarafından sunulan gelişmiş bant genişlikleri ve veri yayılımı, yayımlanacak olup, daha önceleri, olanaksız durumda bulunan ürün ve hizmetleri sağlayacaktır. Belkide, “en önemli uygulama”, basitçe dile getirilecek olursa, internette, sürekli gezer halde olmak, sınırsız ve her ay gideri için makul bir kat hızına sahip olmak demektir. Mevcut 2.5G/3G/3.5G telefon işletimine dayanan hizmetler, sıklıkla pahalı ve uygulamada sınırlıdır. –Seyyare 11:53, 17 Ekim 2007 (UTC)
Already at rates of 15-30 Mbit/s, 4G should be able to provide users with streaming high-definition television. At rates of 100 Mbit/s, the content of a DVD, for example a movie, can be downloaded within about 5 minutes for offline access.
Fixed WiMax and Mobile WiMax are different systems, as of July 2007, all the deployed WiMax is “Fixed Wireless” and is thus not 4G.
İlk 4G Kablosuz Standartları
Visant Stratejileri çalışmasına göre, bu alanda, çok sayıda rekabetçi olacaktır ve aşağıda yer alan yansımaları vermiştir. –Seyyare 12:38, 15 Ekim 2007 (UTC)
-
- WiMAX - 7.2 million units by 2010 (May include fixed and mobile)
- Flash-OFDM - 13 million subscribers in 2010 (only Mobile)
- 3GPP Long Term Evolution of UMTS in 3GPP - valued at US$2 billion in 2010 (~30% of the world population)
- UMB in 3GPP2
- IEEE 802.20
References
See also
- IEEE 802.20
- IEEE 802.21
- Wi-Fi
- WiBro
- WiMAX
- List of Deployed WiMAX networks
- 3GPP Long Term Evolution
- Mesh networking
- 3G, 3.5G, 3.75G - UMTS, HSDPA, HSUPA, HSOPA (LTE), 1xEV-DO, 1xEV-DV
- Handover
- iBurst
- G4
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