4G Technology

4G (also known as Beyond 3G), an abbreviation for Fourth-Generation, is a term used to describe the next complete evolution in wireless communications. A 4G system will be able to provide a comprehensive IP solution where voice, data and streamed multimedia can be given to users on an "Anytime, Anywhere" basis, and at higher data rates than previous generations.

As the second generation was a total replacement of the first generation networks and handsets; and the third generation was a total replacement of second generation networks and handsets; so too the fourth generation cannot be an incremental evolution of current 3G technologies, but rather the total replacement of the current 3G networks and handsets. The international telecommunications regulatory and standardization bodies are working for commercial deployment of 4G networks roughly in the 2012-2015 time scale. At that point it is predicted that even with current evolutions of third generation 3G networks, these will tend to be congested.

There is no formal definition for what 4G is; however, there are certain objectives that are projected for 4G. These objectives include: that 4G will be a fully IP-based integrated system. 4G will be capable of providing between 100 Mbit/s and 1 Gbit/s speeds both indoors and outdoors, with premium quality and high security. [1]

Many companies have taken self-serving definitions and distortions about 4G to suggest they have 4G already in existence today, such as several early trials and launches of WiMAX, which is part of the formal ITU standard for 3G. Other companies have made prototype systems calling those 4G. While it is possible that some currently demonstrated technologies may become part of 4G, until the 4G standard or standards have been defined, it is impossible for any company currently to provide with any certainty wireless solutions that could be called 4G cellular networks that would conform to the eventual international standards for 4G. These confusing statements around "existing" 4G have served to confuse investors and analysts about the wireless industry.

Objectives :

4G is being developed to accommodate the quality of service (QoS) and rate requirements set by forthcoming applications like wireless broadband access, Multimedia Messaging Service (MMS), video chat, mobile TV, HDTV content, Digital Video Broadcasting (DVB), minimal service like voice and data, and other streaming services for "anytime-anywhere". The 4G working group has defined the following as objectives of the 4G wireless communication standard:

A spectrally efficient system (in bits/s/Hz and bits/s/Hz/site),[2]
High network capacity: more simultaneous users per cell,[3]
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,[1]
A data rate of at least 100 Mbit/s between any two points in the world,[1]
Smooth handoff across heterogeneous networks,[4]
Seamless connectivity and global roaming across multiple networks,[5]
High quality of service for next generation multimedia support (real time audio, high speed data, HDTV video content, mobile TV, etc)[5]
Interoperability with existing wireless standards,[6] and
An all IP, packet switched network.[5]
In summary, the 4G system should dynamically share and utilise network resources to meet the minimal requirements of all the 4G enabled users.

Principal technologies:

Baseband techniques[9]
OFDM: To exploit the frequency selective channel property
MIMO: To attain ultra high spectral efficiency
Turbo principle: To minimize the required SNR at the reception side
Adaptive radio interface
Modulation, spatial processing including multi-antenna and multi-user MIMO
Relaying, including fixed relay networks (FRNs), and the cooperative relaying concept, known as multi-mode protocol
It introduces a single new ubiquitous radio access system concept, which will be flexible to a variety of beyond-3G wireless systems.

Wireless System Evolution :

First generation: Almost all of the systems from this generation were analog systems where voice was considered to be the main traffic. These systems could often be listened to by third parties. Some of the standards are NMT, AMPS, Hicap, CDPD, Mobitex, DataTac, TACS and ETACS.

Second generation: All the standards belonging to this generation are commercial centric and they are digital in form. Around 60% of the current market is dominated by European standards. The second generation standards are GSM, iDEN, D-AMPS, IS-95, PDC, CSD, PHS, GPRS, HSCSD, and WiDEN.

Third generation: To meet the growing demands in network capacity, rates required for high speed data transfer and multimedia applications, 3G standards started evolving. The systems in this standard are essentially a linear enhancement of 2G systems. They are based on two parallel backbone infrastructures, one consisting of circuit switched nodes, and one of packet oriented nodes. The ITU defines a specific set of air interface technologies as third generation, as part of the IMT-2000 initiative. Currently, transition is happening from 2G to 3G systems. As a part of this transition, numerous technologies are being standardized.

2.75G:
EDGE/EGPRS
3G:
UMTS (W-CDMA)
CDMA 2000 & 1xEV-DO/IS-856
FOMA
TD-SCDMA
GAN/UMA
WiMax
3.5G:
UMTS (HSDPA)
UMTS (HSUPA)
UMTS (HSPA+)
4G:
Flash-OFDM
3GPP LTE
Fourth generation: According to the 4G working groups, the infrastructure and the terminals of 4G will have almost all the standards from 2G to 4G implemented. Although legacy systems are in place to adopt existing users, the infrastructure for 4G will be only packet-based (all-IP). Some proposals suggest having an open platform where the new innovations and evolutions can fit. The technologies which are being considered as pre-4G are the following: Flash-OFDM, WiMax, WiBro, iBurst, 3GPP Long Term Evolution and 3GPP2 Ultra Mobile Broadband.

IPv6 :

Main articles: Network layer, Internet protocol, and 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.

By the time that 4G is deployed, the process of IPv4 address exhaustion is expected to be in its final stages. Therefore, in the context of 4G, IPv6 support is essential in order to 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 multicast, 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.


Pre-4G wireless standards :

See also section 3G evolution/pre-4G of the 3G article.
According to a Visant Strategies study there will be multiple competitors in this space:[15]

WiMAX - 7.5 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
Fixed WiMax and Mobile WiMax are different systems, as of July 2007, all the deployed WiMax is "Fixed Wireless" and is thus not yet 4G (IMT-advanced) although it can be seen as one of the 4G standards being considered.