Showing posts with label IMT-Advanced. Show all posts
Showing posts with label IMT-Advanced. Show all posts

Thursday 5 September 2019

Opinion: What is "Real 5G" or "True 5G"

I made another opinion piece couple of weeks back. While it was shared already as part of some channels, here is it on the blog with serves as a permanent link. Video and slides below.

As always, I welcome your opinions, comments & suggestions below.

Related Posts:

Saturday 10 September 2011

Monday 11 January 2010

Technologies and Standards for TD-SCDMA Evolutions to IMT-Advanced

Picture Source:

This is a summary of a paper from IEEE Communications Magazine, Dec 2009 issue titled "Technologies and Standards for TD-SCDMA Evolutions to IMT-Advanced" by Mugen Peng and Wenbo Wang of Beijing University of Posts and Telecommunications with my own comments and understanding.

As I have blogged about in the past that China Mobile has launched TD-SCDMA network in China and the main focus to to iron out the basic problems before moving onto the evolved TD-SCDMA network. Couple of device manufacturers have already started working on the TD-HSPA devices. Couple of months back, 3G Americas published a whitepaper giving overview and emphasising the advantages of TDD flavour of LTE as compared to FDD. The next milestone is the IMT-Advanced that is under discussion at the moment and China has already proposed TD-LTE-Advanced which would be compatible with the TD-SCDMA technology.

For anyone who does not know the difference between TDD, FDD and TD-SCDMA please see this blog.

The TD-SCDMA technology has been standardised quite a while back but the rollout has been slow. The commercial TD-SCDMA network was rolled out in 2009 and more and more device manufacturers are getting interested in the technology. This could be due to the fact that China Mobile has a customer base of over 500 million subscribers. As of July 2009 over 100 device manufacturers were working on TD-SCDMA technology.

The big problem with TD-SCDMA (as in the case of R99 3G) is that the practical data rate is 350kbps max. This can definitely not provide a broadband experience. To increase the data rates there are two different approaches. First is the Short Term Evolution (STE) and the other is Long Term Evolution (LTE).

The first phase of evolution as can be seen in the picture above is the TD-STE. This consists of single carrier and multi-carrier TD-HSDPA/TD-HSUPA (TD-HSPA), TD-MBMS and TD-HSPA+.

The LTE part is known as TD-LTE. There is a definite evolution path specified from TD-SCDMA to TD-LTE and hence TD-LTE is widely supported by the TD-SCDMA technology device manufacturers and operators. The target of TD-LTE is to enhance the capabilities of coverage, service provision, and mobility support of TD-SCDMA. To save investment and make full use of the network infrastructure available, the design of TD-LTE takes into account the features of TD-SCDMA, and keeps TD-LTE backward compatible with TD-SCDMA and TD-STE systems to ensure smooth migration.

The final phase of evolution is the 4G technology or IMT-Advanced and the TD-SCDMA candidate for TD-LTE+ is TD-LTE-Advanced. Some mature techniques related to the TD-SCDMA characteristics, such as beamforming (BF), dynamic channel allocation, and uplink synchronization, will be creatively incorporated in the TD-LTE+ system.

Some academic proposals were also made like the one available here on the future evolution of TD-SCDMA but they lacked the industry requirements and are just useful for theoretical research.

The standards of TD-SCDMA and its evolution systems are supervised by 3GPP in Europe and by CCSA (Chinese Cellular Standards Association) in China. In March 2001 3GPP fulfilled TD-SCDMA low chip rate (LCR) standardization in Release 4 (R4). The improved R4 and Release 5 (R5) specifications have added some promising functions including HSDPA, synchronization procedures, terminal location (angle of arrival [AOA]-aided location), and so on.

When the industry standardizations supervised by CCSA are focusing on the integration of R4 and R5, the N-frequency TD-SCDMA and the extension of HSDPA from single- to multicarrier are presented. Meanwhile, some networking techniques, such as N-frequency, polarized smart antenna, and a new networking configuration with baseband unit plus remote radio unit (BBU+RRU), are present in the commercial application of TD-SCDMA.


For the first evolution phase of TD-SCDMA, three alternative solutions are considered. The first one is compatible with WCDMA STE, which is based on HSDPA/HSUPA technology. The second is to provide MBMS service via the compatible multicast broadcast single-frequency network (MBSFN) technique or the new union time-slot network (UTN) technique. The last is HSPA+ to achieve similar performance as LTE.

On a single carrier, TD-HSDPA can reach a peak rate of 2.8 Mb/s for each carrier when the
ratio of upstream and downstream time slots is 1:5. The theoretical peak transmission rate of a three-carrier HSDPA system with 16-quadrature amplitude modulation (QAM) is up to 8.4 Mb/s.

Single-carrier TD-HSUPA can achieve different throughput rates if the configurations and parameters are varied, including the number of occupied time slots, the modulation, and the transport block size in bytes. Considering the complexity of a terminal with several carriers in TD-HSUPA, multicarrier is configured in the Node B, while only one carrier is employed in the terminal.

In Rel-7 based TD-HSPA+, In order to match the performance of orthogonal frequency-division multiple access (OFDMA)-based TD-LTE systems, some advanced techniques are utilized, such as multiple-input multiple-output (MIMO), polarized BF, higher modulation and coding schemes (64-QAM is available), adaptive fast scheduling, multicarrier techniques, and so on. Theoretically, 64-QAM can improve performance by a factor of 1.5 compared to the current 16-QAM; for single-carrier the peak rate reaches 4.2 Mb/s, and three-carrier up to 12.6 Mb/s.

For the MIMO technique, double transmit antenna array (D-TxAA), based on the pre-coding method at the transmitter, has been employed in frequency-division duplex (FDD)-HSPA+ systems, while selective per antenna rate control (S-PARC), motivated by the Shannon capacity limit for an open loop MIMO link, has been applied in TD-HSPA+ systems.


The TD-SCDMA LTE program was kicked off in November 2004, and the LTE demand report was approved in June 2005. The LTE specified for TD_SCDMA evolution is named TD-LTE.

LTE systems are supposed to work in both FDD and TDD modes. LTE TDD and FDD modes have been greatly harmonized in the sense that both modes share the same underlying framework, including radio access schemes OFDMA in downlink and SC-FDMA in uplink, basic subframe formats, configuration protocols, and so on.

TD-LTE trials have already started last year with some positive results.


IMT-Advanced can be regarded as a B3G/4G standard, and the current TD-SCDMA standard migrating to IMT-Advanced can be regarded as a thorough revolution. TD-LTE advanced (TD-LTE+) is a good match with the TD-SCDMA revolution to IMT-Advanced.

It is predicted that the future TD-SCDMA revolution technology will support data rates up to approximately 100 Mb/s for high mobility and up to approximately 1 Gb/s for low mobility such as nomadic/local wireless access.

Recently, some advanced techniques have been presented for TD-LTE+ in China, ranging from the system architecture to the radio processing techniques, such as multi-user (MU)-BF, wireless relaying, and carrier aggregation (CA).

For MU-BF see the paper proposed by Huawei, CHina Mobile and CATT here (

For Wireless Relaying see the ZTE paper here (

To achieve higher performance and target peak data rates, LTE+ systems should support bandwidth greater than 20 MHz (e.g., up to 100 MHz). Consequently, the requirements for TD-LTE+ include support for larger transmission bandwidths than in TD-LTE. Moreover, there should be backward compatibility so that a TD-LTE user can work in TD-LTE+ networks. CA is a concept that can provide bandwidth scalability while maintaining backward compatibility with TD-LTE through any of the constituent carriers, where multiple component carriers are aggregated to the desired TD-LTE+ system bandwidth. A TD-LTE R8 terminal can receive one of these component carriers, while an TD-LTE+ terminal can simultaneously access multiple component carriers. Compared to other approaches, CA does not require extensive changes to the TD-LTE physical layer structure and simplifies reuse of existing implementations. For more on Carrier Aggregation see CATT, LGE and Motorola paper here (

Finally, there are some interesting developments happening in the TD-SCDMA market with bigger players getting interested. Once a critical mass is reached in the number of subscribers as well as the manufacturers I wouldnt be surprised if this technology is exported beyond the Chinese borders. With clear and defined evolution path this could be a win-win situation for everyone.

Wednesday 28 October 2009

China proposes TD-LTE-Advanced as its candidate for 4G

The International Telecommunication Union (ITU) has recently received six candidate technology submissions, including China's domestically-developed TD-LTE-Advanced for the global 4G (IMT-Advanced) mobile wireless broadband technology.

China's Ministry of Industry and Information Technology (MIIT) said on October 26 that it will fully support TD-LTE-Advanced in competing to be qualified as global 4G standard technology and promote development of related industries.

TD-LTE-Advanced, which is the intellectual property of China, inherits some of the major technical elements of TD-SCDMA, but will be able to offer an extended bandwidth and higher speed for Internet access.

Currently, 3GPP's LTE-advanced and IEEE's 802.16m are the two major 4G technologies. TD-LTE-Advanced was submitted at the ITU meeting as IMT-Advanced candidate technology, which is supported by major telecom operators and network device manufacturers including France Télécom, Deutsche Telekom, AT&T, NTT, KT, China Mobile, Ericsson, Nokia, Huawei and ZTE.

The selected technologies are expected to be accorded the official designation of IMT-Advanced - to qualify as true 4G technologies - in October 2010.

I was unable to locate more information on TD-LTE-Advanced. Will update once I have some more info.

Tuesday 20 October 2009

IMT-Advanced Proposals by 3GPP and IEEE

The proposals for IMT-Advanced that I mentioned about earlier have been put up on 3G4G website.

The 3GPP proposal for LTE-Advanced is here.

The IEEE proposal for 802.16m is here.

Thursday 15 October 2009

On Relay Technology in LTE-Advanced and WiMAX standards

I blogged earlier about Relay technology that is part of LTE-Advanced. In the IEEE Communications Magazine, this month there is a complete article on Relay technology. Here is a brief summary from that paper with my own understanding (and words).

We have mentioned about IMT-Advanced and LTE-Advanced before. International Mobile Telecommunications-Advanced is going to be the first 4G technology and as i discussed earlier, there are two main technologies vying for the 4G crown. I am sure both are as good and both will succeed. From 3GPP point of view, the standards will be part of Release-10 and should be ready end 2010 or beginning 2011. The understanding is that IMT-Advanced systems will support peak data rates of 100 Mb/s in high mobility environment (up to 350 km/h) and 1 Gb/s in stationary and pedestrian environments (up to 10 km/h). The transmission bandwidth of IMT-Advanced systems will be scalable and can change from 20 to 100 MHz, with downlink and uplink spectrum efficiencies in the ranges of [1.1, 15 b/s/Hz] and [0.7, 6.75 b/s/Hz], respectively. There will be a minimum requirement on voice over IP (VoIP) capacities in high- and low-mobility environments of around 30 and 50 active users/sector/MHz. The latency for control and user planes should be less than 100 ms and 10 ms, respectively, in unloaded conditions.

As I mentioned last week, the 3GPP candidate for IMT-Advanced is LTE-Advanced. On the IEEE front, 802.16j group published the relay-based multihop techniques for WiMAX and IEEE 802.16m has been submitted for the IMT-Advanced approval last week. The normal 802.16 WiMAX standard has been approved as 3G standard by the ITU.

So what exactly are Relays. Relay transmission can be seen as a kind of collaborative communications, in which a relay station (RS) helps to forward user information from neighboring user equipment (UE)/mobile station (MS) to a local eNode-B (eNB)/base station (BS). In doing this, an RS can effectively extend the signal and service coverage of an eNB and enhance the overall throughput performance of a wireless communication system. The performance of relay transmissions is greatly affected by the collaborative strategy, which includes the selection of relay types and relay partners (i.e., to decide when, how, and with whom to collaborate).

There are two different terminology used for Relay's. First is Type-I and Type-II and other is non-transparency and transparency. Specifically, a Type-I (or non-transparency) RS can help a remote UE unit, which is located far away from an eNB (or a BS), to access the eNB. So a Type-I RS needs to transmit the common reference signal and the control information for the eNB, and its main objective is to extend signal and service coverage. Type-I RSs mainly perform IP packet forwarding in the network layer (layer 3) and can make some contributions to the overall system capacity by enabling communication services and data transmissions for remote UE units. On the other hand, a Type-II (or transparency) RS can help a local UE unit, which is located within the coverage of an eNB (or a BS) and has a direct communication link with the eNB, to improve its service quality and link capacity. So a Type-II RS does not transmit the common reference signal or the control information, and its main objective is to increase the overall system capacity by achieving multipath diversity and transmission gains for local UE units.

Different relay transmission schemes have been proposed to establish two-hop communication between an eNB and a UE unit through an RS. Amplify and Forward — An RS receives the signal from the eNB (or UE) at the first phase. It amplifies this received signal and forwards it to the UE (or eNB) at the second phase. This Amplify and Forward (AF) scheme is very simple and has very short delay, but it also amplifies noise. Selective Decode and Forward — An RS decodes (channel decoding) the received signal from the eNB (UE) at the first phase. If the decoded data is correct using cyclic redundancy check (CRC), the RS will perform channel coding and forward the new signal to the UE (eNB) at the second phase. This DCF scheme can effectively avoid error propagation through the RS, but the processing delay is quite long. Demodulation and Forward — An RS demodulates the received signal from the eNB (UE) and makes a hard decision at the first phase (without decoding the received signal). It modulates and forwards the new signal to the UE (eNB) at the second phase. This Demodulation and Forward (DMF) scheme has the advantages of simple operation and low processing delay, but it cannot avoid error propagation due to the hard decisions made at the symbol level in phase one.

Relay starts becoming interesting because according to the 3GPP LTE-Advanced and IEEE 802.16j, an RS can act as the BS for legacy UE units and should have its own physical cell identifier. It should be able to transmit its own synchronization channels, reference symbols and downlink control information. So an RS shall have the full functions of an eNB/BS (except for traffic backhauling), including the capabilities of knowing the radio bearer of received data packets and performing traffic aggregation to reduce signaling overhead. There should be no difference between the cell controlled by an RS and that controlled by a normal eNB.

There are much more details and simulation results in the IEEE article. For those interested, can always get hold of the article and dig deeper.
More information also available in the following:

Friday 9 October 2009

IMT-Advanced Proposals to be discussed next week

Depending on which camp you belong to, you would have read atleast one press release.

The 3GPP Partners, which unite more than 370 leading mobile technology companies, made a formal submission to the ITU yesterday, proposing that LTE Release 10 & beyond (LTE-Advanced) be evaluated as a candidate for IMT-Advanced. Complete press release here.

The IEEE today announced that it has submitted a candidate radio interface technology for IMT-Advanced standardization in the Radiocommunication Sector of the International Telecommunication Union (ITU-R).

The proposal is based on IEEE standards project 802.16m™, the “Advanced Air Interface” specification under development by the IEEE 802.16™ Working Group on Broadband Wireless Access. The proposal documents that it meets ITU-R’s challenging and stringent requirements in all four IMT-Advanced “environments”: Indoor, Microcellular, Urban, and High Speed. The proposal will be presented at the 3rd Workshop on IMT-Advanced in Dresden on 15 October in conjunction with a meeting of ITU-R Working Party 5D. Complete press release here.

The workshop next week will see lots of announcements, discussions and debates about both these technologies. More details on workshop here. My 3G4G page on LTE-Advanced here.
I am sure there is a place for both these technologies and hopefully both of them will succeed :)

Friday 13 February 2009

Whitepaper: Mobile Broadband Evolution

3G Americas has released this new paper that can be downloaded from here.

An extract of what it contains from its preface:

This new 2009 paper, The Mobile Broadband Evolution: 3GPP Release 8 and Beyond provides detailed discussions on the HSPA+ enhancements in Rel-8 as well as the EPS, EPC and LTE architecture, features/capabilities and performance estimates. The paper also addresses 3GPP planning for Rel-9 and Rel-10 content which has already begun. In addition to further enhancements to Evolved HSPA or HSPA+, Rel-9 will be focused on features that enhance upon the Rel-8 EPC/LTE capabilities in areas such as location, emergency and broadcast services, support of CS over LTE, Home NodeB/eNodeB architecture considerations (i.e. support for femtocell type applications) and IMS evolution. Further, a new study item in 3GPP will define evolution of the LTE technology to meet IMT-Advanced requirements (called LTE-Advanced), at the same time as work is commencing on the above Rel-9 enhancements. 3GPP recognizes the need to develop a solution and specification to be submitted to the International Telecommunication Union (ITU) for meeting the IMT-Advanced requirements, and therefore, in parallel with Rel-9 work, 3GPP is working on the LTE-Advanced study item which is likely to define the bulk of the content for Rel-10. The white paper The Mobile Broadband Evolution: 3GPP Release 8 and Beyond includes discussion of Rel-10 and what requirements will officially define "4G" technologies with the significant new technology enhancements to EPC/LTE for meeting the very aggressive IMT-Advanced requirements.

Tuesday 9 December 2008

LTE Advanced: NSN Proves relaying technology

Nokia Siemens Networks has broken new ground with another technological first: mobile broadband communications beyond LTE. Company researchers have successfully demonstrated Relaying technology proposed for LTE-Advanced, enabling an exceptional end-user experience delivered consistently across the network.

Completed in Nokia Siemens Networks research facilities in Germany, the demonstration illustrated how advances to Relaying technology can further improve the quality and coverage consistency of a network at the cell edge - where users are furthest from the mobile broadband base station.

Relaying technology, which can also be integrated in normal base station platforms, is cost efficient and easy to deploy as it does not require additional backhaul. The demonstration of LTE Advanced means operators can plan their LTE network investments knowing that the already best-in-class LTE radio performance, including cell edge data rates, can be further improved and that the technological development path for the next stage of LTE is secure and future-proof.

These performance enhancements have been achieved by combining an LTE system supporting a 2x2 MIMO (Multiple Input Multiple Output) antenna system, and a Relay station. The Relaying operates in-band, which means that the relay stations inserted in the network do not need an external data backhaul. They are connected to the nearest base stations by using radio resources within the operating frequency band of the base station itself. Towards the terminal they are base stations and offer the full functionality of LTE. LTE-Advanced is currently being studied by 3GPP for Release 10 and will be submitted towards ITU-R as the 3GPP Radio Interface Technology proposal.

The improved cell coverage and system fairness - meaning offering higher user data rates for and fair treatment of users distant from the base station - will allow operators to utilise existing LTE network infrastructure and still meet growing bandwidth demands.

The demonstration has been realised by using an intelligent demo relay node embedded in a test network forming a FDD in-band self-backhauling solution for coverage enhancements. With this demonstration the performance at the cell edge could be increased up to 50% of the peak throughput.

More info on LTE-A coming soon.

Monday 13 October 2008

What on earth is this 4G, anyway?

Over the past two years I have been hearing a lot about next generation technologies. It all started by 3.5G i.e. HSPA evolution etc and hence the debate entered into the area of 4G.
Everybody comes along on the blogs, articles, tech magazines etc and make himself/herself comfortable as per their liking with the word 4G.

Some people use the term "4G" to describe WiMAX technology. This terminology i.e. 4G used by WiMax camp does indeed upset some people specially the ones in the LTE camp.

Everyday I come across individuals who have different view regarding the 4G terms. Some do shockingly tell me that neither WiMax nor LTE is a 4G technology rather LTE evolution or LTE advanced will be termed as a 4G technology.

I have literally reached to stage now where I think I should give up now and just leave to almighty to decide what actually a 4G technology is. If you ask me about my personal opinion on this then my view is quite clear in this. I categorize 1G as analog mobile, 2G as digital, 3G as CDMA, and 4G as anything using OFDM. It's pretty simple, it is straightforward, there's not a lot of haggling.

Wikipedia says "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."

By the Wikipedia definition, three out of four definitions are met under the existing definitions of WiMAX; nobody thinks that the current definition of WiMAX is going to be able to crank up to 1 Gbit/sec, but life, as they say, ain't so simple.

A spokesperson for Nokia has said "There's no official owner of who defines 4G," and you would think if anyone could tell you what 4G was/is/will be, it would be Nokia.

ITU-R is in the process of defining IMT-Advanced, but, funny enough, the standards body has backed away from the phrase 4G. IMT-Advanced is a "big tent" term that will/may/should encompasses 802.16m and LTE-Advanced which in turn are faster than WiMAX and LTE standards respective. Maybe?

If I understand this descent into acronyms and definitions, even the forthcoming, first generation LTE would not qualify as a 4G technology. That is, if we call IMT-Advanced as the term formerly known as 4G - but not called 4G by ITU-R.

I know this whole argument of 4G terms upset many people. They think and rightly so that the whole concept behind a 'Standards Body' is so that such arguments are moot. These guys think that people use different terms to coin their own standards for marketing, one-upmanship and generally nonconformist attitudes.

Well let's hope that some day somebiody will come out with a clear idnetity of the 4G technology which is acceptable to everybody. Meanwhile my friend in the picture above is working hard to find out what 4G really is.

Thursday 21 August 2008

Revised paper on “4G” by 3G Americas

3G Americas have published a revised paper on Defining “4G”: Understanding the ITU Process for IMT-Advanced.

3G Americas initially created this white paper one year ago to provide clear understanding regarding the work-in-progress by the ITU, the sole organization responsible for determining the specifications for IMT-Advanced. The current paper updates the considerable progress made by the ITU, establishing a basis for what should be included in an IMT-Advanced system.

While speculation has been going on about 4G technologies, ITU is close to releasing a full set of documentation for this definition. It has held ongoing consultations with the global community over many years on this topic in Working Party 8F under the scope of a work item known as Question ITU-R 229-1/8 “Future development of IMT-2000 and systems beyond IMT-2000.” Following a year-end 2007 restructure in ITU-R, this work is being addressed under the new Study Group 5 umbrella (replacing the former Study Group 8) by Working Party 5D which is the new name for the former WP 8F.

This work in WP 8F, and now WP 5D, has woven together a definition, recipe, and roadmap for the future beyond 3G that is comprised of a balance among a Market and Services View, a Technology View, and a Spectrum View. These, along with Regulatory aspects, are the key elements for business success in wireless.

By mid-2008, ITU-R advanced beyond the vision and framework and developed a set of requirements by which technologies and systems can, in the near future, be determined as a part of IMT- Advanced and in doing so, earn the right to be considered 4G.

During 2008 and though 2009, ITU-R will hold an open call for the “first invitation” of 4G (IMTAdvanced) candidates. Subsequent to the close of the submission period for the “first invitation” an assessment of those candidates' technologies and systems will be conducted under the established ITU-R process, guidelines, and timeframes for this IMT-Advanced ‘first invitation.” The culmination of this open process will be a 4G, or IMT-Advanced family. Such a 4G family, in adherence to the principles defined for acceptance into this process, is globally recognized to be one which can grow to include all aspects of a marketplace that will arrive beyond 2010, thus complementing and building upon an expanding and maturing 3G business.

The paper is available to download from here.

The ITU-R Radiocommunication Bureau has established an “IMT-Advanced” web page ( to facilitate the development of proposals and the work of the evaluation groups. The IMT-Advanced web page provides details of the process for the submission of proposals, and will include the RIT and SRIT submissions, evaluation group registration and contact information, evaluation reports and other relevant information on the development of IMTAdvanced.

Monday 18 August 2008

4G: Where are we now.

Last month i read this news about WiMAX leading the world of 4G and last week I read about an American carrier selecting LTE as its choice of 4G technology. Since ITU has decided that they wont be using the term 4G in future and rather use IMT-Advanced or LTE-Advanced, I guess 4G is up for grabs.
The main driver for '4G' is data. Recently carriers have become agressive and started offering some decently priced 'Wireless Broadband' data plans. Rather than confuse people with HSDPA, etc., they have decided to use the term 'Wireless Broadband' or 'Mobile Broadband'. Personally both the terms have managed to confuse some people who associate Mobile Broadband with Internet access on Mobile and Wireless Broadband as broadband on WiFi.

Andrew Seybold makes some valid points in an article in Fierce Wireless. One of the things that he points out is that LTE may tout on higher data rates as compared to others, that is only possble in 20MHz of spectrum. In real world this kind of spectrum is near impossible to obtain. If the spectrum flexibility is removed than HSPA+, LTE, EV-DO Rev B and WiMAX have nearly the same data rates and performance.

For HSPA+ the existing infrastructure can be reused and a software upgrade would suffice whereas for LTE new infrastructure would be required. NTT DoCoMo has fully committed to being the first LTE network operator and others are raising their hands. He thinks that nationwide LTE networks would only be available around 2014.

While I agree with this analysis completely, I think what is going to dictate this transformation from 3G+ to LTE for the operators will be the uptake of data on a network. The biggest advantage of LTE is that it is able to operate in TDD and FDD mode. Operators that have been traditionally using FDD mode of operation will change their loyalty to TDD mode so that they can use asymmetric data transfer. This can provide more capacity in case of some special event taking place (Football finals, Reality show results, etc.) where the users are just interested in receiving information rather than sending any. For operators with paired spectrums, they can use both the band seperately in TDD modes.

Gigaom has list of American operators that are involved in 4G and the list is quite interesting:
  • AT&T: USA's largest network in terms of subscribers, AT&T plans to use LTE to upgrade to 4G, but not for a long, long time. For now it’s content with its current 3G network. It will upgrade to HSPA+ in 2009 and 2010. Eventually it will go to LTE, but won’t begin testing until 2010 or 2011 with full deployment coming after that.
  • Verizon Wireless: Verizon is already testing LTE equipment from several vendors, with plans to roll out the network in 2010 and have most of the country covered by 2012; Verizon’s would likely be the first full U.S. deployment of the LTE technology.
  • Sprint-Nextel: The outlier in the whole transition to 4G, Sprint is going with WiMAX rather than LTE. After a number of delays, the company is set to launch its network in September. By the end of the year it will join with Clearwire to operate a nationwide WiMAX network under the Clearwire brand.
  • T-Mobile: T-Mobile is still launching its 3G coverage, so its 4G networks may take a while to come to fruition. The carrier’s German parent appears to favor LTE.
  • Metro PCS: This budget carrier plans to use LTE but it doesn’t yet have a time frame for deployment, pointing out that its customers aren’t heavy data users yet.
  • U.S. Cellular: The company is unsure of its deployment plans but it would likely choose to follow the rest of the industry with LTE. As for deployment, the time frame isn’t set.
  • Leap Wireless: Recently said it had not made a decision or public comment about its 4G plans.

The picture is a bit different here in UK because all the operators are going to LTE. There may be some ISP's that may be tempted to move to WiMAX as they would get economy of scale. There is also the news of BT (the largest landline phone provider) planning to roll out nationwide WiMAX network in the 2.6GHz spectrum. If BT is able to fulfil its ambition that it could be a big win for the people.

Tuesday 22 April 2008

More on LTE-Advanced

LTE-Advanced should be real broadband wireless networks that provide equal or greater peak data rates than those for wired networks, i.e., FTTH (Fiber To The Home), while maintaining equivalent QoS. Smooth introduction of LTE-Advanced should be possible on top of LTE system.

High-level requirements
•Reduced network cost (cost per bit)
•Better service provisioning
•Compatibility with 3GPP systems


WRC 07 identified the following new bands for use by IMT/IMT-Advanced:

  • 450−470 MHz band,
  • 698−862 MHz band,
  • 790−862 MHz band,
  • 2.3−2.4 GHz band, and
  • 3.4−3.6 GHz band.

Not all of these bands are available on a worldwide basis. These bands are in addition to the bands currently specified in 3GPP. Specification for C-band should not be restricted to 3.4 – 3.6 GHz, but cover 3.4 to 3.8 and even 3.4 to 4.2 GHz as these will likely become available in some countries.

Channel Bandwidth

  • Channel bandwidths up to 100 MHz to be specified
  • However, for many operators consecutive allocation of 100 MHz unlikely
  • optimised performance needed for smaller bandwidths of e.g. 50 MHz low cost/complexity (i.e. not fully flexible) resource aggregation to be considered
Interworking with legacy 3GPP RAT
  • Full low complexity (for NW and terminal) interworking with 3GPP RAT, so operator de facto has flexibility on technology to deploy, when and where. The networks of most operators will be a combination of multiple 3GPP RAT for many years to come.
  • Network Sharing: Support for at least all currently specified Network Sharing features, also to facilitate cost-efficient roll out of LTE-Advanced, including, but not limited to, rural area coverage.
Working Methods
  • As LTE-Advanced should be an evolution of LTE, it is essential that it is specified as part of the 36-series of specifications.
  • It is also essential work is performed to a large degree by the experts that developed LTE, and thus work ideally should be performed in existing Working Groups.
  • LTE-Advanced will likely constitute the next significant development step for LTE, but (smaller) stand-alone enhancements and additions to LTE should be possible, and progressed in parallel.
  • Some of these smaller enhancements, as well as the “corrections” to LTE Release 8 could/should be captured in Rel.9, where SAE considerations will lead to relatively short Release completion time-frame.
More details on LTE-Advanced workshop in China here.

The workshop docs are available here.

LTE-Advanced = IMT-Advanced = 4G(or 5G?)

The 3GPP TSG RAN workshop on IMT-Advanced was held (in the week after the RAN WG meetings) on April 7-8, 2008 in Shenzhen, China hosted by ZTE Corporations. The main conclusions from the workshop are:
  • LTE Advanced shall be an evolution of LTE.
    o LTE terminal shall be supported in LTE-advanced networks.
    o An LTE-Advanced terminal can work in an LTE part of the network.
    o Primary focus of LTE-Advanced is low mobility users.
  • All requirements/targets in TR25.913 apply to LTE-Advanced.LTE-Advanced requirements shall fulfill IMT-Advanced requirements within the ITU-R time plan
  • For LTE-Advanced:
    o Same inter-RAT interworking capability with at least same performance as in LTE Release 8
    o Intra-RAT handover performance shall be same or better than LTE Release 8
  • As a way forward for LTE-Advanced it was agreed:
    o TSG RAN email reflector for LTE-Advanced will be established (the new reflector is called 3GPP_TSG_RAN_LTE_ADVANCED and it is available since 21.04.2008)
    § Email discussions on LTE-Advanced requirements will be started on this reflector (moderator: Takehiro Nakamura, NTT DoCoMo, LTE-Advanced SI rapporteur).
    o A new TR will be created (after the workshop it was decided to create TR 36.913 "Requirements for LTE-Advanced") to include LTE-Advanced requirements and updated by RAN WG meetings in May 2008 referring to structure of 25.913 and outcome of the workshop.(note: Allocation of the TR number was done after the workshop.)
    o Review of the outcome of this workshop and kick-off of discussions about LTE-Advanced requirements and technical solutions in RAN WG meetings in May 2008 in Kansas City.The goal is to complete LTE-Advanced requirements at RAN #40 in Prague end of May 2008 according to agreed work plan (i.e. TR 36.913 will be provided to RAN #40).

Thursday 19 July 2007

Defining 4G (I mean IMT-Advanced)

3G Americas published a new white paper entitled "Defining 4G: Understanding the ITU Process for the Next Generation of Wireless Technology". The white paper provides the factual description of how IMT-Advanced or 4G will someday be defined by the International Telecommunications Union (ITU). ITU is the internationally recognized authority that will produce the official definition of the next generation of wireless technologies beyond IMT-2000 or 3G.

Chris Pearson, President of 3G Americas, stated, "The ITU is currently establishing criteria for IMT-Advanced and will be screening various technologies for inclusion in the IMT-Advanced family. Only then will we understand what is and can be rightly and credibly called 4G.” He continued, "Any claim today that a particular technology is a so-called ‘4G technology’, in reality, is simply a marketing spin, creating market confusion and deflating the importance of the telecommunications industry standards. Technologies should be verified against a set of agreed-upon requirements in order to qualify as 4G, and this will happen in the future when the requirements are outlined by the ITU."

Significant progress has been made by the Radiocommunication Sector of the ITU (ITU-R) in establishing an agreed and globally accepted definition of 4G wireless systems, and ITU-R is close to releasing a full set of documentation for this definition. Working under a mandate to address systems beyond 3G, ITU-R has progressed from delivering a vision of 4G in 2002 to establishing a name for 4G in 2005 (IMT-Advanced). In 2006, ITU-R set out the principles for the process of the development of IMT-Advanced. The work of the ITU encompasses the important elements of business success in the wireless industry, especially the balance of a market and services view, a technology view, a spectrum view and regulatory aspects. In early 2008, ITU-R will translate the vision into a set of requirements by which technologies and systems can, in the near future, be determined a part of IMT-Advanced and in doing so, earn the credible right to be considered 4G.

During 2008 and 2009, ITU-R will hold an open call for 4G (IMT-Advanced) candidates as well as an assessment of those candidates' technologies and systems. The culmination of this open process will be a 4G, or IMT-Advanced family of technologies. Such a 4G family of technologies, in adherence to the principles defined for acceptance into this ITU process, is globally recognized to be one which can grow to include all aspects of a marketplace that will arrive beyond 2010.

“Third generation technologies are growing immensely in the marketplace, but they too once started out with a vision and requirements from ITU,” stated Pearson. “The evolving wireless marketplace and its customers will be well served by the current ITU process for the next generation of wireless services.”

As can be seen in the picture above, the main requirements for 4G are as follows:
  • Peak data rate of 100Mbps for high mobility applications such as mobile access
  • Approx. 1Gbps for low mobility applications such as nomadic/local wireless access
A very important point in the report is what i have been saying for years:

The communications industry is witnessing significant posturing about wireless technologies and systems that are claiming to be “4G.” Any claim that a particular technology is a 4G technology or system today is, in reality, simply
a market positioning statement by the respective technology advocate. Such claims must be verified and substantiated against a set of requirements in order to qualify as 4G.

Wednesday 6 June 2007

IMT Advanced = 4G

In this story on Telecom TV, is says:

Working under a mandate to address "systems beyond 3G", the working party has now come up with a name for the future mobile systems. Thankfully, they are veering away from 4G and are calling it 'IMT-Advanced'.

A simple search on Google returned some useful information from Telecom ABC:

International Mobile Telecommunications - Advanced (IMT-Advanced) is a concept from the ITU for mobile communication systems with capabilities which go further than that of IMT-2000. IMT-Advanced was previously known as “systems beyond IMT-2000”.

It is foreseen that the development of IMT-2000 will reach a limit of around 30 Mbps. In the vision of the ITU, there may be a need for a new wireless access technology to be developed around the year 2010 capable of supporting even higher data rates with high mobility, which could be widely deployed around the year 2015 in some countries. The new capabilities of these IMT-Advanced systems are envisaged to handle a wide range of supported data rates according to economic and service demands in multi-user environments with target peak data rates of up to approximately 100 Mbit/s for high mobility such as mobile access and up to approximately 1 Gbit/s for low mobility such as nomadic/local wireless access.

To support this wide variety of services, it may be necessary for IMT-Advanced to have different radio interfaces and frequency bands for mobile access for highly mobile users and for new nomadic/local area wireless access.

Together with the introduction of the name IMT-Advanced, the ITU introduced the generic root name IMT. The generic root name IMT covers the capabilities of IMT-2000, including future development of IMT-2000, and IMT-Advanced.

Meanwhile a story in ChinaTechNews is suggesting that Datang Telecom has already written a Draft on 4G and is working on 3G&4G convergence. Cannot find much more on this right now.

For more on 4G technologies, either read this story on Network World or 3G4G website.