International Mobile Telecommunications-Advanced (IMT-Advanced Standard) are requirements issued by the ITU-R of the International Telecommunication Union (ITU) in 2008 for what is marketed as 4G (or sometimes as 4.5G) mobile phone and Internet access service.
An IMT-Advanced system is expected to provide a comprehensive and secure all-IP based mobile broadband solution to laptop computer wireless modems, smartphones, and other mobile devices. Facilities such as ultra-broadband Internet access, IP telephony, gaming services, and streamed multimedia may be provided to users.
IMT-Advanced intended to accommodate the quality of service (QoS) and rate requirements set by further development of applications like mobile broadband access, Multimedia Messaging Service (MMS), video chat, mobile TV, but also new services like High-definition television (HDTV). 4G may allow roaming with wireless local area networks, and may interact with digital video broadcasting systems. It was meant to go beyond the International Mobile Telecommunications-2000 requirements, which specify mobile phones systems marketed as 3G.
Specific requirements of the IMT-Advanced report included:
- Based on an all-Internet Protocol (IP) packet switched network
- Interoperability with existing wireless standards
- 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.
- Dynamically share and use the network resources to support more simultaneous users per cell.
- Scalable channel bandwidth 5–20 MHz, optionally up to 40 MHz
- Peak link spectral efficiency of 15 bit/s/Hz in the downlink, and 6.75 bit/s/Hz in the uplink (meaning that 1 Gbit/s in the downlink should be possible over less than 67 MHz bandwidth)
- System spectral efficiency of up to 3 bit/s/Hz/cell in the downlink and 2.25 bit/s/Hz/cell for indoor usage
- Seamless connectivity and global roaming across multiple networks with smooth handovers
- Ability to offer high quality of service for multimedia support
The first set of 3GPP requirements on LTE Advanced was approved in June 2008.
A summary of the technologies that have been studied as the basis for LTE Advanced is included in a technical report.
While the ITU adopts requirements and recommendations for technologies that would be used for future communications, they do not actually perform the development work themselves, and countries do not consider them binding standards. Other trade groups and standards bodies such as the Institute of Electrical and Electronics Engineers (IEEE), the WiMAX Forum and 3GPP also have a role.
Physical layer transmission techniques expected to be used include:
- MIMO: To attain ultra high spectral efficiency by means of spatial processing including multi-antenna and multi-user MIMO
- Frequency-domain-equalization, for example Multi-carrier modulation (OFDM) in the downlink or single-carrier frequency-domain-equalization (SC-FDE) in the uplink: To exploit the frequency selective channel property without complex equalization.
- Frequency-domain statistical multiplexing, for example (OFDMA) or (Single-carrier FDMA) (SC-FDMA, Linearly precoded OFDMA, LP-OFDMA) in the uplink: Variable bit rate by assigning different sub-channels to different users based on the channel conditions
- Turbo principle error-correcting codes: To minimize the required SNR at the reception side
- Channel-dependent scheduling: To utilize the time-varying channel.
- Link adaptation: Adaptive modulation and error-correcting codes
- Relaying, including fixed relay networks (FRNs), and the cooperative relaying concept, known as multi-mode protocol
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) antenna arrays, are used.
The CDMA spread spectrum radio technology used in 3G systems and IS-95 is abandoned and replaced by OFDMA and other frequency-domain equalization schemes. This is combined with MIMO (Multiple In Multiple Out), antenna arrays, dynamic channel allocation and channel-dependent scheduling.
The first publicly available LTE service was opened in the two Scandinavian capitals Stockholm (Ericsson system) and Oslo (a Huawei system) on 14 December 2009, and branded 4G. The user terminals were manufactured by Samsung. Currently, all four major US wireless carriers offer LTE services.
In South Korea, SK Telecom and LG U+ have enabled access to LTE service since July 2011 for data devices, slated to go nationwide by 2012.
Mobile WiMAX (IEEE 802.16e)
The Mobile WiMAX (IEEE 802.16e-2005) mobile wireless broadband access (MWBA) standard (marketed as WiBro in South Korea) is sometimes branded 4G, and offers peak data rates of 128 Mbit/s downlink and 56 Mbit/s uplink over 20 MHz wide channels.
|Peak download||128 Mbit/s|
|Peak upload||56 Mbit/s|
Ultra Mobile Broadband
Ultra Mobile Broadband (UMB) was the brand name for a discontinued 4G project within the 3GPP2 standardization group to improve the CDMA2000 mobile phone standard for next generation applications and requirements. In November 2008, Qualcomm, UMB's lead sponsor, announced it was ending development of the technology, favouring LTE instead. The objective was to achieve data speeds over 275 Mbit/s downstream and over 75 Mbit/s upstream.
At an early stage the Flash-OFDM system was expected to be further developed into a 4G standard.
iBurst and MBWA
The iBurst technology, using High Capacity Spatial Division Multiple Access (HC-SDMA), was at an early stage considered as a 4G predecessor. It was incorporated by the Mobile Broadband Wireless Access (MBWA) working group into the IEEE 802.20 standard in 2008.
In October 2010, ITU-R Working Party 5D approved two industry-developed technologies. On December 6, 2010, ITU noted that while current versions of LTE, WiMax and other evolved 3G technologies do not fulfill IMT-Advanced requirements for 4G, some may use the term "4G" in an "undefined" fashion to represent forerunners to IMT-Advanced that show "a substantial level of improvement in performance and capabilities with respect to the initial third generation systems now deployed."
LTE Advanced (Long-term-evolution Advanced) was formally submitted by the 3GPP organization to ITU-T in the fall 2009, and expected to be released in 2012. The target of 3GPP LTE Advanced was to reach and surpass the ITU requirements. LTE Advanced is an improvement on the existing LTE network. Release 10 of LTE is expected to achieve the LTE Advanced speeds. Release 8 in 2009 supported up to 300 Mbit/s download speeds which was still short of the IMT-Advanced standards.
WiMAX Release 2 (IEEE 802.16m)
The WirelessMAN-Advanced evolution of IEEE 802.16e was published in May 2011 as standard IEEE 802.16m-2011. The relevant industry promoting the technology gave it the marketing name of WiMAX Release 2. It had an objective to fulfill the IMT-Advanced criteria. The IMT-Advanced group formally approved this technology as meeting its criteria in October 2010. In the second half of 2012, the 802.16m-2011 standard was rolled up into the 802.16-2012 standard, excluding the WirelessMAN-Advanced radio interface part of the 802.16m-2011 standard, which got moved to IEEE Std 802.16.1-2012.
The following table shows a comparison of IMT-Advanced candidate systems as well as other competing technologies.
|Family||Primary Use||Radio Tech||Downstream
|HSPA+ is widely deployed. Revision 11 of the 3GPP states that HSPA+ is expected to have a throughput capacity of 672 Mbit/s.|
|LTE||3GPP||General 4G||OFDMA/MIMO/SC-FDMA||100 Cat3
(in 20 MHz FDD) 
(in 20 MHz FDD)
|LTE-Advanced update expected to offer peak rates up to 1 Gbit/s fixed speeds and 100 Mb/s to mobile users.|
|WiMax rel 1||802.16||WirelessMAN||MIMO-SOFDMA||37 (10 MHz TDD)||17 (10 MHz TDD)||With 2x2 MIMO.|
|WiMax rel 1.5||802.16-2009||WirelessMAN||MIMO-SOFDMA||83 (20 MHz TDD)
141 (2x20 MHz FDD)
|46 (20 MHz TDD)
138 (2x20 MHz FDD)
|With 2x2 MIMO.Enhanced with 20 MHz channels in 802.16-2009|
|WiMAX rel 2||802.16m||WirelessMAN||MIMO-SOFDMA||2x2 MIMO
110 (20 MHz TDD)
183 (2x20 MHz FDD)
219 (20 MHz TDD)
365 (2x20 MHz FDD)
70 (20 MHz TDD)
188 (2x20 MHz FDD)
140 (20 MHz TDD)
376 (2x20 MHz FDD)
|Also, low mobility users can aggregate multiple channels to get a download throughput of up to 1 Gbit/s|
mobility up to 200 mph (350 km/h)
|Mobile range 30 km (18 miles)
extended range 55 km (34 miles)
|Mobile Internet||OFDM/MIMO||288.8 (using 4x4 configuration in 20 MHz bandwidth) or 600 (using 4x4 configuration in 40 MHz bandwidth)|
|iBurst||802.20||Mobile Internet||HC-SDMA/TDD/MIMO||95||36||Cell Radius: 3–12 km
Speed: 250 km/h
Spectral Efficiency: 13 bits/s/Hz/cell
Spectrum Reuse Factor: "1"
|EDGE Evolution||GSM||Mobile Internet||TDMA/FDD||1.6||0.5||3GPP Release 7|
|HSDPA is widely deployed. Typical downlink rates today 2 Mbit/s, ~200 kbit/s uplink; HSPA+ downlink up to 56 Mbit/s.|
|UMTS-TDD||UMTS/3GSM||Mobile Internet||CDMA/TDD||16||Reported speeds according to IPWireless using 16QAM modulation similar to HSDPA+HSUPA|
|EV-DO Rel. 0
|Rev B note: N is the number of 1.25 MHz carriers used. EV-DO is not designed for voice, and requires a fallback to 1xRTT when a voice call is placed or received.|
Notes: All speeds are theoretical maximums and will vary by a number of factors, including the use of external antennas, distance from the tower and the ground speed (e.g. communications on a train may be poorer than when standing still). Usually the bandwidth is shared between several terminals. The performance of each technology is determined by a number of constraints, including the spectral efficiency of the technology, the cell sizes used, and the amount of spectrum available. For more information, see Comparison of wireless data standards.
- Werner Mohr (2002). "Mobile Communications Beyond 3G in the Global Context" (PDF). Siemens mobile. Retrieved 2007-03-26.
- Noah Schmitz (March 2005). "The Path To 4G Will Take Many Turns". Wireless Systems Design. Retrieved 2007-03-26.
- Kim Young Kyun; Prasad, Ramjee (2006). 4G Roadmap and Emerging Communication Technologies. Artech House 2006. pp. 12–13. ISBN 1-58053-931-9.
- "Report M.2134: Requirements related to technical performance for IMT-Advanced radio interface(s)". ITU-R. November 2008. Retrieved August 25, 2011.
- Moray Rumney, "IMT-Advanced: 4G Wireless Takes Shape in an Olympic Year", Agilent Measurement Journal, September 2008 Archived 2016-01-17 at the Wayback Machine.
- Hussain, Sadia; Sadia Hussain, Zara Hamid; Naveed S. Khattak (May 30–31, 2006). "Proceedings of the first international conference on Integrated internet ad hoc and sensor networks - InterSense '06". Proceedings of the first international conference on Integrated internet ad hoc and sensor networks. Association for Computing Machinery: 14. doi:10.1145/1142680.1142698. ISBN 1-59593-427-8.
- 3GPP specification: Requirements for further advancements for E-UTRA (LTE Advanced)
- 3GPP Technical Report: Feasibility study for Further Advancements for E-UTRA (LTE Advanced)
- G. Fettweis; E. Zimmermann; H. Bonneville; W. Schott; K. Gosse; M. de Courville (2004). "High Throughput WLAN/WPAN" (PDF). WWRF. Archived from the original (PDF) on 2008-02-16.
- "Light Reading Mobile - 4G/LTE — Ericsson, Samsung Make LTE Connection — Telecom News Analysis". Unstrung.com. Retrieved 2010-03-24.[permanent dead link]
- Cesa, Dante (July 5, 2011). "SK Telecom and LG U+ launch LTE in Seoul, fellow South Koreans seethe with envy". Engadget. Retrieved August 25, 2011.
- "South Korea launches WiBro service". EE Times. 2006-06-30. Retrieved 2010-06-23.
- "Sprint announces seven new WiMAX markets, says 'Let AT&T and Verizon yak about maps and 3G coverage'". Engadget. 2010-03-23. Retrieved 2010-04-08.
- Qualcomm halts UMB project, Reuters, November 13th, 2008
- IEEE Standard for Local and metropolitan area networks — Part 20: Air Interface for Mobile Broadband Wireless Access Systems Supporting Vehicular Mobility — Physical and Media Access Control Layer Specification (PDF). Official standard document. IEEE Standards Association. August 29, 2008. ISBN 978-0-7381-5766-5.
- "ITU paves way for next-generation 4G mobile technologies". News release. October 21, 2010. Retrieved August 25, 2011.
- "ITU World Radiocommunication Seminar highlights future communication technologies".
- Parkvall, Stefan; Dahlman, Erik; Furuskär, Anders; Jading, Ylva; Olsson, Magnus; Wänstedt, Stefan; Zangi, Kambiz (21–24 September 2008). LTE Advanced – Evolving LTE towards IMT-Advanced (PDF). Vehicular Technology Conference Fall 2008. Stockholm: Ericsson Research. Retrieved 26 November 2010. External link in
- Stefan Parkvall; David Astely (April 2009). "The Evolution of LTE towards IMT-Advanced". Journal of Communications. 4 (3): 146–154. doi:10.4304/jcm.4.3.146-154. Archived from the original on August 10, 2011. Retrieved August 25, 2011.
- "Draft IEEE 802.16m System Description Document" (PDF). IEEE WirelessMAN-Advanced workgin group. April 30, 2008. Retrieved August 25, 2011.
- "IEEE Approves IEEE 802.16m - Advanced Mobile Broadband Wireless Standard". News release. IEEE Standards Association. March 31, 2011. Retrieved August 20, 2011.
-  Archived January 27, 2012, at the Wayback Machine.
- "LTE". 3GPP web site. 2009. Retrieved August 20, 2011.
- "WiMAX and the IEEE 802.16m Air Interface Standard" (PDF). WiMax Forum. 4 April 2010. Retrieved 2012-02-07.