4G

4G is the fourth generation of cellular network technology, succeeding 3G and designed to support all-IP communications and broadband services, enabling a variety of data-intensive applications.

Additionally, 4G has enabled the widespread adoption of cloud computing, fixed wireless access, and real-time data exchange for the Internet of Things (IoT), facilitating the growth of connected devices and smart systems.

4G has also significantly expanded the availability of mobile TV, with numerous dedicated applications and services making it widely accessible to users.

The improved network capacity and lower latency also support high-speed, low-latency applications, enhancing user experience in activities such as online gaming and live broadcasts.

It was eventually succeeded by 5G, which introduced even faster speeds, lower latency, and the ability to support advanced use cases across various industries.

[5] Since the first-release versions of Mobile WiMAX and LTE support much less than 1 Gbit/s peak bit rate, they are not fully IMT-Advanced compliant, but are often branded 4G by service providers.

[6] Mobile WiMAX Release 2 (also known as WirelessMAN-Advanced or IEEE 802.16m) and LTE Advanced (LTE-A) are IMT-Advanced compliant backwards compatible versions of the above two systems, standardized during the spring 2011,[citation needed] and promising speeds in the order of 1 Gbit/s.

The peak bit rate is further improved by smart antenna arrays for multiple-input multiple-output (MIMO) communications.

LTE has a theoretical net bit rate capacity of up to 100 Mbit/s in the downlink and 50 Mbit/s in the uplink if a 20 MHz channel is used — and more if multiple-input multiple-output (MIMO), i.e. antenna arrays, are used.

[17] As of November 2012, the five publicly available LTE services in the United States are provided by MetroPCS,[18] Verizon Wireless,[19] AT&T Mobility, U.S. Cellular,[20] Sprint,[21] and T-Mobile US.

[citation needed] In South Korea, SK Telecom and LG U+ have enabled access to LTE service since 1 July 2011 for data devices, slated to go nationwide by 2012.

[citation needed] In June 2006, the world's first commercial mobile WiMAX service was opened by KT in Seoul, South Korea.

[27] Sprint has begun using Mobile WiMAX, as of 29 September 2008, branding it as a "4G" network even though the current version does not fulfill the IMT Advanced requirements on 4G systems.

[28] In Russia, Belarus and Nicaragua WiMax broadband internet access were offered by a Russian company Scartel, and was also branded 4G, Yota.

But viewing from the current development trend, whether this standard advocated by China Mobile will be widely recognized by the international market is still debatable.

In November 2008, Qualcomm, UMB's lead sponsor, announced it was ending development of the technology, favoring LTE instead.

The iBurst system (or HC-SDMA, High Capacity Spatial Division Multiple Access) was at an early stage considered to be a 4G predecessor.

The following key features can be observed in all suggested 4G technologies: As opposed to earlier generations, 4G systems do not support circuit switched telephony.

These are based on efficient FFT algorithms and frequency domain equalization, resulting in a lower number of multiplications per second.

As IPv4 addresses are (nearly) exhausted,[Note 1] IPv6 is essential to support the large number of wireless-enabled devices that communicate using IP.

Apart from this, the reliability in transmitting high speed data in the fading channel can be improved by using more antennas at the transmitter or at the receiver.

Both transmit/receive diversity and transmit spatial multiplexing are categorized into the space-time coding techniques, which does not necessarily require the channel knowledge at the transmitter.

[63] A major issue in 4G systems is to make the high bit rates available in a larger portion of the cell, especially to users in an exposed position in between several base stations.

In current research, this issue is addressed by macro-diversity techniques, also known as group cooperative relay, and also by Beam-Division Multiple Access (BDMA).

[64] Pervasive networks are an amorphous and at present entirely hypothetical concept where the user can be simultaneously connected to several wireless access technologies and can seamlessly move between them (See vertical handoff, IEEE 802.21).

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.

5G promises even faster speeds, lower latency, and the ability to connect a vast number of devices simultaneously.