2.5G is a stepping stone between 2G and 3G cellular wireless technologies. The term "second and a half generation" is used to describe 2G-systems that have implemented a packet switched domain in addition to the circuit switched domain. It does not necessarily provide faster services because bundling of timeslots is used for circuit switched data services (HSCSD) as well.
The first major step in the evolution of GSM networks to 3G occurred with the introduction of General Packet Radio Service (GPRS). CDMA2000 networks similarly evolved through the introduction of 1xRTT. So the cellular services combined with enhanced data transmission capabilities became known as '2.5G.'
GPRS could provide data rates from 56 Kbit/s up to 115 Kbit/s. It can be used for services such as Wireless Application Protocol (WAP) access, Multimedia Messaging Service (MMS), and for Internet communication services such as email and World Wide Web access. 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 utilizing the capacity or is in an idle state.
1xRTT supports bi-directional (up and downlink) peak data rates up to 153.6 kbps, delivering an average user data throughput of 80-100 kbps in commercial networks. It can also be used for WAP, SMS & MMS services, as well as Internet access.
2.2.4. 2.75G (EDGE)
GPRS networks evolved to EDGE networks with the introduction of 8PSK encoding. Enhanced Data rates for GSM Evolution, Enhanced GPRS (EGPRS), or IMT Single Carrier (IMT-SC) is a backward-compatible digital mobile phone technology that allows improved data transmission rates, as an extension on top of standard GSM. EDGE was deployed on GSM networks beginning in 2003—initially by Cingular (now AT&T) in the United States.
EDGE is standardized by 3GPP as part of the GSM family, and it is an upgrade that provides a potential three-fold increase in capacity of GSM/GPRS networks. The specification achieves higher data-rates (up to 236.8 Kbit/s) by switching to more sophisticated methods of coding (8PSK), within existing GSM timeslots.
a. In between 2G and 3G there is another generation called 2.5G
b. 2.5G represents handsets with data capabilities over GPRS
c. But this had not brought out any new revolution
2.2.5 3G Wireless system
International Mobile Telecommunications-2000 (IMT--2000), better known as 3G or 3rd Generation, is a generation of standards for mobile phones and mobile telecommunications services fulfilling specifications by the International Telecommunication Union. The use of 3G technology is also able to transmit packet switch data efficiently at better and increased bandwidth. 3G mobile technologies proffers more advanced services to mobile users. The spectral efficiency of 3G technology is better than 2G technologies. Spectral efficiency is the measurement of rate of information transfer over any communication system. 3G is also known as IMT-2000.
a. Transmission speeds from 125kbps to 2Mbps
b. In 2005, 3G is ready to live up to its performance in computer networking (WCDMA, WLAN and Bluetooth) and mobile devices area (cell phone and GPS)
c. Data are sent through technology called packet switching
d. Voice calls are interpreted using circuit switching
e. Access to Global Roaming
f. Clarity in voice calls
g. Fast Communication, Internet, Mobile T.V, Video Conferencing, Video Calls, Multi Media Messaging Service (MMS), 3D gaming, Multi-Gaming etc are also available with 3G phones
FIG.2.5.1 3G Mobile Phone
2.2.6. 4G Wireless system
4G refers to the fourth generation of cellular wireless standards. It is a successor to 3G and 2G families of standards. The nomenclature of the generations generally refers to a change in the fundamental nature of the service, non-backwards compatible transmission technology, and new frequency bands.3G technologies make use of TDMA and CDMA. 3G (Third Generation Technology) technologies make use of value added services like mobile television, GPS (global positioning system) and video conferencing. The basic feature of 3G Technology (Third Generation Technology) is fast data transfer rates. However this feature is not currently working properly because, ITU 200 is still making decision to fix the data rates. It is expected that 2mbit/sec for stationary users, while 348kbits when moving or travelling. ITU sell various frequency rates in order to make use of broadband technologies. Network authentication has won the trust of users, because the user can rely on its network as a reliable source of transferring data.3G technology is much flexible, because it is able to support the 5 major radio technologies. These radio technologies operate under CDMA, TDMA and FDMA.CDMA holds for IMT-DS (direct spread), IMT-MC (multi carrier). TDMA accounts for IMT-TC (time code), IMT-SC (single carrier). FDMA has only one radio interface known as IMT-FC or frequency code. Third generation technology is really affordable due to the agreement of industry. This agreement took place in order to increase its adoption by the users. 3G (Third Generation Technology) system is compatible to work with the 2G technologies. 3G (Third Generation Technology) technologies holds the vision that they should be expandable on demand. The aim of the 3G (Third Generation Technology) is to allow for more coverage and growth with minimum investment.
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:
a. Mobile TV – a provider redirects a TV channel directly to the subscriber's phone where it can be watched.
b. Video on demand – a provider sends a movie to the subscriber's phone.
c. Video conferencing – subscribers can see as well as talk to each other.
d. Tele-medicine – a medical provider monitors or provides advice to the potentially isolated subscriber.
e. Location-based services – a provider sends localized weather or traffic conditions to the phone, or the phone allows the subscriber to find nearby businesses or friends
f. mobile ultra-broadband (gigabit speed) access and multi-carrier transmission.
g. Mobile WiMAX (Worldwide Interoperability for Microwave Access)
a. 4G is a conceptual framework and a discussion point to address future needs of a high speed wireless network
b. It offer both cellular and broadband multimedia services everywhere
c. Expected to emerged around 2010 – 2015
d. 4G should be able to provided very smooth global roaming ubiquitously with lower cost
FIG 2.6.1. 4G Mobile Phone
2.2.7. 5G Wireless system
5G (5th generation mobile networks or 5th generation wireless systems) is a name used in some research papers and projects to denote the next major phase of mobile telecommunications standards beyond the upcoming 4G standards (expected to be finalized between approximately 2011 and 2013). Currently, 5G is not a term officially used for any particular specification or in any official document yet made public by telecommunication companies or standardization bodies such as 3GPP, WiMAX Forum or ITU-R. New 3GPP standard releases beyond 4G and LTE Advanced are in progress, but not considered as new mobile generations. The implementation of standards under a 5G umbrella would likely be around the year of 2020.
a. 5G is a completed wireless communication with almost no limitation; somehow people called it REAL wireless world
b. Additional features such as Multi-Media Newspapers, also to watch T.V programs with the clarity as to that of an HD T.V.
c. We can send Data much faster that that of the previous generations
d. 5G will bring almost perfect real world wireless or called “WWWW: World Wide Wireless Web
e. Real wireless world with no more limitation with access and zone issues.
f. Wearable devices with AI capabilities.
g. Internet protocol version 6 (IPv6), where a visiting care-of mobile IP address is assigned according to location and connected network.
h. One unified global standard.
i. Pervasive networks providing ubiquitous computing: The user can simultaneously be connected to several wireless access technologies and seamlessly move between them (See Media independent handover or vertical handover, IEEE 802.21, also expected to be provided by future 4G releases). These access technologies can be a 2.5G, 3G, 4G or 5G mobile networks, Wi-Fi, PAN or any other future access technology. In 5G, the concept may be further developed into multiple concurrent data transfer paths.
j. Cognitive radio technology, also known as smart-radio: allowing different radio technologies to share the same spectrum efficiently by adaptively finding unused spectrum and adapting the transmission scheme to the requirements of the technologies currently sharing the spectrum. This dynamic radio resource management is achieved in a distributed fashion, and relies on software defined radio. See also the IEEE 802.22 standard for Wireless Regional Area Networks.
k. High altitude stratospheric platform station (HAPS) systems.