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Showing posts with label TD-LTE. Show all posts
Showing posts with label TD-LTE. Show all posts

Wednesday, 2 July 2014

Case Study: Migrating from WiMAX to TD-LTE



I was glad to hear this case study by Mike Stacey where they have a WiMAX network already deployed and are in process of moving to TD-LTE. Along with the technical issues there are also business and customer issues that need to be taken into account while doing this technology swap. Surprisingly 3.5GHz is also not a very popular band because there are very few deployments in this spectrum. On the other hand, most of the companies worldwide that have been able to get their hands on this spectrum, generally got a big chunk (60-100MHz) so they would be able to do CA easily (bar the technical issues of Intra-band interference).

Anyway, the presentation is embedded below. Hope you find it useful. If you know of similar experiences, please feel free to add them in the comments.


Sunday, 27 October 2013

TDD-FDD Joint CA


From a recent NTT Docomo presentation (embedded below). Whereas right now 3GPP has only been working on FDD or TDD scenarios, this proposal is a combination of FDD as P-Cell and TDD as S-Cell. Inter-Technology carrier aggregation is another possible option. Anyway, the complete presentation is below.


LTE-Advanced Enhancements and Future Radio Access Toward 2020 and Beyond from Zahid Ghadialy

Updated on 29/10/2013

3GPP has already started working on this work item. See RP-131399 for details.

Monday, 9 September 2013

LTE TDD - universal solution for unpaired spectrum?



TDD deployments are gathering pace. An earlier GSA report I posted here, highlighted the many devices that are TD-LTE ready.
The main thing that is being emphasised is that from the standards point of view, not much additional efforts are required for a TDD device as compared to an FDD device. Of course in practice the physical layer would be different and that could be a challenge in itself.

Qualcomm published a presentation on this topic that is embedded below. Available to download from here.



Wednesday, 21 August 2013

eIMTA: Enhanced Interference Mitigation & Traffic Adaptation


eIMTA is one of the features being discussed in 3GPP Rel-12. The pictures above and below provide the details.
As can be seen, at the moment all the eNodeB's associated with a network has to transmit the same UL/DL pattern throughout out the system. With eIMTA, each eNodeB can decide the UL/DL pattern itself depending on the load.
The main challenge would be interference management while using this scheme.

See also, this slideshare presentation for details:


Wednesday, 3 October 2012

#LTEAsia 2012 Highlights - via Alan Quayle

A summary of LTE Asia 2012, slides and highlights via Alan Quayle blog.



Some of the interesting findings from the conference include:
  • TD-LTE is gaining momentum, and its beyond WiMAX operators and China mobile, many APAC operators are considering it for unpaired spectrum and to efficiently meet the asymmetric capacity requirements of mobile broadband which is mainly download
  • Software defined radio and self-organizing networks are proving critical to manage operational costs
  • Single RAN is proving the best way to manage network performance
  • Signaling is in a mess - what is the good of standards when it creates such a mess?
  • IMS gaps continue - what is the good of standards when it doesn't meet basic migration needs?
  • The SS7 guys have reinvented themselves as the Diameter guys
  • Business model innovation - LTE is not just for mobile devices, LTE is for quad play and an interesting array of business applications
  • The 3G network of many operators is congested - forcing the move to LTE
  • CSFB (Circuit Switched Fall Back) works
  • VoLTE testing / roaming / network issues remain - given voice remains by revenue the core service, our industry should be ashamed we're having so many problems with VoLTE
  • A belief on OTT partnering, but not quantification on the OTT's willingness to pay for QoS (Quality of Service)
  • Many operators have a question mark on the use of WiFi off-load - its not a technology issue rather one of economics and customer experience, LTE-A and small cells in hotspots appears to be the focus.

Briefly reviewing the slides shown below:

  • LTE Data Points
    • 96 Commercial LTE deployments mainly in the 1.8 and 2.8GHz bands
    • APAC has 40% of LTE subscribers, likely to be the high growth region
    • Drivers for LTE: Throughput, efficiency and low latency
    • TD-LTE: 12 commercial deployments, 24 contracts and 53 Trials
    • Streaming video dominates traffic on handheld devices, with YouTube being the top traffic generator at 27% of peak traffic
  • South Korea Data Explosion
    • South Korea has seen OTT explode, Kakao Talk 51 mins of usage per day
    • 20 times smartphone growth in 2 years (28M in June 2012, 53% penetration)
    • 60 times mobile data growth to 37TB per month in 2 years, 32% is from LTE devices
    • LTE subs use 2.9GB per month compared to 3G sub on average use 1.2GB
    • LTE subs reached 10M, 141% monthly growth
    • Customer drive for LTE is speed (37%) and latest device (31%)
    • Challenge Jan 2010 and Jan 2012 ARPU fallen from $48-$35 while data use risen from 180MB to 992MB
    • Focus beyond voice, messaging and data into VAS: virtual goods (Korean thing), ICT (Information and Communication Technology) and cloud services / solutions (focus on enterprise)
  • HK CSL Migration to LTE
    • 3G is congested, LTE is not
    • Key is LTE devices available, unlike the early 3G days
    • Migrating customers away from unlimited plans to family and shared plans that deliver value
    • LTE sub uses 2-5 times the data of 3G subs
    • CSFB works
    • Average speed seen is 20 Mbps
    • Using Software Defined Radio, Single vendor RAN, Self-Organizing Networks
    • Migration to LTE-A, small cells and WiFi where appropriate
  • Starhub's migration to LTE (they launched LTE at the event)
    • 50% of voice traffic is still on 2G
    • Using AMR to re-farm 2G spectrum to LTE
    • Site access is critical - drive to software defined radio to avoid site visits
  • NTT DoCoMo's VoLTE Evolution
    • 70% devices in portfolio are now LTE
    • All smartphones support CSFB
    • Drive to VoLTE is simply to switch off 3G voice (2G already off)
    • BUT IMS has missing functionality / standards - migration from 3G to VoLTE is not easy - example of failing in standards on basic issues
  • Yes: Example of innovative converged 4G operator in an developing market that uses web principles for service delivery
  • Role of Mobile Identity in BYOD (Bring Your Own Device)
    • BYOD is as significant a trend if APAC as any other market
    • Provides a nice review of the approaches in managing BYOD
  • LTE Quad-Play in Emerging Markets: TD-LTE case study
  • Smartphone growth implications: Review of the signaling problem and mitigation strategies across 3G and LTE.  Highlights challenge current standards process 


Read the complete post here.

Tuesday, 21 February 2012

Softbank Japan's Ultra Wifi 4G (a.k.a AXGP)


In Japan, they love to re-brand the standard technologies into something more interesting to attract people's attention. In a way they are right as they want to offer a service rather than a technology. Couple of years back NTT Docomo launched its Crossy service, that was offering LTE with upto 75Mbps dl speeds. Yesterday, I read about Softbank launching their 4G service that is based on AXGP format.

I did blog about XGP many years back but AGXP, which stands for Advanced XGP may not be very well related to XGP. According to ZTE Technologies magazine:

In November 2011, Japan’s third largest mobile operator, Softbank, made AXGP commercially available. AXGP is similar to TD-LTE, and has been deployed in Japan in conjunction with ZTE and Huawei. Two thousand base stations were built in the fi rst phase, and there will be up to 10,000 base stations built in the second phase. Ninety-nine percent of the Japanese population will be covered by 2012. So far, the Softbank network is the largest commercial TD-LTE network in the world. Wang Jianzhou, chairman of China Mobile, said, “If in the past the TD-LTE network was just a stratagem on paper, now it has turned into a reality.”

The following are some more details edited from a Japanese website (translation via Chrome):


High-speed data communication service Wireless City Planning of the SOFTBANK Group (Wireless City Planning, WCP) will be scheduled after February 2012, adopted a new communication method AXGP is, in excess of up to 100Mbps downlink high-speed communication is a feature . It was an opportunity to use the test machine prior to the start of service for general users, to report a sense of its use. 


 "AXGP" was developed inherit the "PHS" next generation of Willcom

 "AXGP" high-speed data transmission technology WCP employs a technology that was originally planned to use the 2.5GHz band has been assigned from the Ministry of Internal Affairs and Communications Willcom to deploy as "PHS" next generation. Had to expand the limited service area and some intended for users under the name of "WILLCOM CORE XGP" PHS is then the next generation, business is XGP is "Wireless City Planning" of Softbank subsidiary company under the reorganization proceedings of Willcom inheritance. Provide the service as "AXGP" form of communication is an evolved version of XGP in WCP.


 AXGP, in addition to the XGP also hand while inheriting the "micro cell" was characteristic of PHS, PHS has been developed as the next generation, that have become compatible with the method of TD-LTE. Including China and India, that are compatible with the TD-LTE system is expected to expand in many parts of the world, the benefits can be expected that international expansion is expected. 

 Service is initially started up to 76Mbps. The first bullet is the mobile router products

 AXGP is at present, but services have been provided for users in a small part had been using the service test XGP Willcom old, since the February 2012 service "SoftBank 4G for general users as MVNO Softbank Mobile plans to start ". The communication speed up to 110Mbps downstream and 15Mbps and maximum upstream and downstream speeds in excess of 100Mbps for speed has become a feature.


 At the start of service, the mobile router will "101SI" made of (SII) will be released at the same time Seiko Instruments. However, 101SI has become a maximum 76Mbps to 110Mbps falling down is the theoretical value of the service, at the start of the service is not provided in the full spec. Terminal is planned to also provide support AXGP Then, in the year 2012 is also powered smartphone will be compatible with AXGP. In addition, "101SI" to support (42Mbps maximum downlink, 5.7Mbps uplink maximum) "ULTRASPEED" Softbank mobile. 




Ultra-high speed in the area. Hope to plan area at the time of service and rates

 Although a measurement with the outdoor area was limited, with respect to communication speed was very good results with the results fit. Most favorable conditions and even the user does not exist before the start of the service say that already provide services as high-speed data communication, "Xi" of NTT DoCoMo, Inc., or UQ Communications 37.5Mbps, which is the maximum theoretical value of outdoor (Kurosshi~i) It was also a number greater than the maximum 40Mbps "UQ WiMAX" of is very encouraging.


 However, the decisive factor in mobile data communications is not only communication speed, three elements of the communication charge is important and easy-to-use, deployment area, including "ease of connection." In the area at the moment of some are very fast and are limited in the Yamanote Line, but is a matter of course in order before the service, ease of connection of the fact there are many parts of the still unknown. Also, I'd be anxious and services are provided in the fee structure what.


 SoftBank is to introduce a flat-rate voice among their users ahead of any other mobile phone operators so far, campaigns expand the iPhone however any inexpensive flat-rate packet. Further has a track record of just made me started to increase subscribers by the "straight-line with anyone" WILLCOM has also continued to decline in subscribers. Softbank Mobile also be deployed as a MVNO, at the time of release of the service that you want to use the AXGP expect a bold expansion of unique services and Softbank WCP, which is the same group Softbank.


Softbank's website is billing this as 'Ultra Wifi 4G' and will be launched to public this Friday, just in time for MWC12.

Friday, 18 November 2011

Interoperability between LTE FDD/TDD network

In countries where FDD and TDD are both in use, it would be interesting to see Dual-mode LTE terminals that would support both TDD and FDD and it should be possible to do a reselection as well has handovers from one mode to another.

It should be noted that the Structure of TDD and FDD frames are different as shown above.

If you are wondering why we need both FDD and TDD modes in the same geographical location, its because of Spectrum being available as well as with TDD allows possibility of different UL/DL data rates which generally means more efficient use of spectrum.

Monday, 16 August 2010

Nokia Siemens Networks demonstrate TD-LTE leadership

Since last few months, NSN have been showing that they are serious about TD-LTE as well. Back in June they made an announcement that they have integrated TD-LTE in their networks so that it can support concurrent use of TD-SCDMA and TD-LTE. They opened a TD-LTE lab in China as well earlier this year.

Motorola is another big player in the TD-LTE arena and I have blogged about them as well. With the purchase of Motorola Networks by NSN, it got additional experience and capability to be the next TD-LTE leader. With this renewed confidence, it ended the joint venture with Huawei which started back in 2005 with TD-SCDMA technology.

The following is press release from NSN couple of days back:

Nokia Siemens Networks has proven its leading role in advancing TD-LTE as it met the complete TD-LTE test specifications defined by China’s Ministry of Industry and Information Technology (MIIT). The successful completion of the trial in the 2.3GHz band at the MIIT lab in Beijing, China, marks an important milestone in the commercialization of TD-LTE. After the test, Nokia Siemens Networks also achieved the world’s first high-definition TD-LTE video call, including handover, with a Samsung TD-LTE device.

The high-definition video call demo showcased interoperability between Nokia Siemens Networks’ LTE infrastructure and Samsung’s TD-LTE USB dongle, and marks a definitive step toward ensuring early availability of a functioning TD-LTE ecosystem for commercial deployments.

“We’ve achieved excellent results from this test and are happy to partner with Nokia Siemens Networks in driving the TD-LTE ecosystem further,” said Mr. Tong Wang, president of Beijing Samsung Telecom R&D Center. “Commercial readiness of devices is a key indicator for the success of a new technology and the current test results show that we are now well prepared for TD-LTE.”

“Meeting TD-LTE test specifications defined by MIIT and achieving the first high-definition video call with handover, are key milestones in our list of achievements, added Paul Pan, head of Network Systems, Greater China Region, Nokia Siemens Networks. “We will continue to collaborate with partners to accelerate our progress toward a comprehensive deployment of TD-LTE.”

Nokia Siemens Networks is at the forefront of TD-LTE development and commercialization, actively working with telecom operators and device manufacturers. The company recently announced the first TD-LTE interoperability data call with a prototype TD-LTE USB dongle from Samsung and the first TD-LTE video call between Shanghai and Taipei.


Ericsson is now going to probably have tough competition from NSN.

Tuesday, 27 April 2010

Softbank and Ericsson for TD-LTE as well

Last week I blogged about TD-LTE in India and China, today I found out that there is more interest in TD-LTE:

From Fierce Wireless:

Ericsson, the world's largest wireless infrastructure vendor, is looking to gain more expertise is the area, and this week signed an MoU to create a strategic cooperation with Datang Telecom in China to develop TDD solutions and likely gain a foothold in China Mobile's planned TD-LTE network.

As part of the deal, Ericsson will begin integrating Datang's TD-SCDMA radio access network equipment into its own 3G offering. TD-SCDMA is China's homegrown 3G standard that China Mobile and others are using. TD-LTE is seen as the next generation of TD-SCDMA.

From Telecom Asia:

Japanese cellco Softbank Mobile is considering deploying the Chinese-developed TD-LTE standard as a 4G network.

Senior executive vice president Ted Matsumoto told telecomasia.net the company could deploy it in the 2.5GHz spectrum it gained access to when it
bought a stake in failing PHS operator Willcom last month.

But he said
Willcom’s next-gen PHS technology, XGP, and mobile Wimax were also under consideration.

“We’re going to have 2.5GHz TDD spectrum, so we will seriously explore TD-LTE,” he said.

The XGP technology was “very much like TD, or at least is compatible with TD-LTE.”

Softbank is also focused on winning access to the key 700MHz or 900MHz frequencies, the “golden spectrum” with a much higher propagation range already that is used by both of its competitors.

“We’re fighting the handicap game [without those frequencies],” Matsumoto said. “There’s no 100% assurance, but we definitely will seek a 700/900MHz license.”

Japan’s Ministry of Internal Affairs & Communications plans to allocate 40MHz of spectrum in the 700/900MHz ranges for LTE and is now conducting a review.

For the time being, Softbank has put LTE plans on the backburner in favor of HSPA+.

It shut down its 2G network last month and is looking to reap the cost benefits of running a single 3G/3.5G network with up to 42Mbps download speeds.

Monday, 19 April 2010

All eyes on TD-LTE in India and China


The TD-SCDMA and Long Term Evolution (TD-LTE) network will be massively deployed in China, the world's largest telecommunications country by number of telecoms users, in 2010, globally premier international market research and consulting firm Infonetics Research said in a forecast report.
More and more mobile carriers have started developing the LTE, including Verizon Communications Inc., China Mobile Ltd., and China Telecom Corporation Ltd., Infonetics noted. There will be no more than twenty LTE networks in the world at the end of 2010.

China Mobile Communications, the largest mobile telecom carrier in China, will establish three experimental TD-LTE (time division-long term evolution) networks separately in three coastal cities - Qingdao, Xiamen and Zhuhai - beginning the third quarter of 2010, according to the China-based China Business News Daily.

China's Ministry of Industry and Information Technology (MIIT), the carrier, handset and component makers, and handset solution suppliers in China in late 2008 began to cooperate for the development of TD-LTE in three phases, the report said.

The first-phase trial of technological concepts completed in June 2009, and the ongoing R&D and experiments in the second phase will be finished at the end of June 2010, the report indicated, adding the third phase will begin with China Mobile setting up three trial networks in the third quarter.

China Mobile Communications, the largest mobile telecom carrier in China, on April 15 inaugurated its first experimental TD-LTE network at the site of the 2010 Shanghai World Expo.

The trial network consists of 17 outdoor TD-LTE base stations made by Huawei Technologies completely covering the 5.28km square site and will be used to provide mobile high-definition multimedia services.

ZTE and Datang Mobile Communications Equipment as well as Motorola and Alcatel-Lucent have also set up TD-LTE access points inside a number of pavilions.

Motorola, Inc.'s Networks business has already announced in February that it has successfully deployed a TD-LTE network at the Expo Center for World Expo 2010 Shanghai China, and completed the first indoor over-the-air (OTA) TD-LTE data sessions at the site. These advancements demonstrate another milestone of collaborative industry efforts on TD-LTE commercialization, reaffirming Motorola's commitment to address the future needs of TDD spectrum operators in China and around the world.

These milestones follow the announcement by China Mobile Communications Corporation (CMCC) in 2009, that Motorola was selected as main equipment supplier to provide indoor TD-LTE coverage for pavilions at Shanghai Expo. During the Shanghai Expo, Motorola will provide an advanced end-to-end TD-LTE solution and the world's first TD-LTE USB dongles. Motorola will also leverage its orthogonal frequency division multiplexing (OFDM) expertise with professional services to deploy, maintain and optimize these leading-edge networks. Visitors will be able to experience applications such as high-definition video on demand, remote monitoring and high-speed Internet access services.

Motorola, Inc.'s Networks business announced on April 16th that it showcased an end-to-end TD-LTE demonstration via the world's first TD-LTE USB dongle at the Shanghai Expo site to support the "TD-LTE Showcase Network Opening Ceremony" hosted in Shanghai on April 15. Delegates at the ceremony experienced applications that run over a TD-LTE network via USB dongles, including high-definition video wall (simultaneous 24 video streams), remote monitoring and high-speed Internet browsing applications. This latest advancement demonstrates a major milestone of the collaborative industry efforts in building a healthy TD-LTE device ecosystem, reaffirming Motorola's commitment to TDD spectrum operators around the world.

Motorola, a leading provider of TD-LTE technology, and China Mobile share the same commitment to accelerating TD-LTE commercialization and globalization. "We are very excited to support China Mobile in bringing the world's first TD-LTE USB dongle demonstration enabled by our TD-LTE system," said Dr. Mohammad Akhtar, corporate vice president and general manager, Motorola Networks business in Asia Pacific. "A healthy devices ecosystem has always been critical to the development, commercialization and success of wireless network technologies. We are working closely with partners to drive this ecosystem as demonstrated by the advancement announced today. TD-LTE is now a commercial reality and we are very pleased to see that industry players are joining forces to accelerate TD-LTE globalization."

Interest in TD-LTE continues to grow because of several key factors: the low cost of TDD spectrum that is particularly attractive to emerging and developing markets; operators' continuing need for more capacity and spectrum; and the ability to hand-off between TD-LTE and LTE FDD networks. In effect, this ability to roam between LTE FDD and TD-LTE means operators can use TD-LTE networks to augment their FDD LTE network for more capacity or other applications such as video broadcasting, while operators choosing to use TD-LTE as their "main" network can still offer their subscribers the ability to roam to other operators' FDD LTE networks in different countries. Motorola is one of the few vendors in the industry that has expertise in, and is committed to investing in both FDD-LTE and TD-LTE, as well as WiMAX. By leveraging its orthogonal frequency division multiplexing (OFDM) expertise and WiMAX legacy, Motorola has built up its leadership position in TD-LTE with a number of industry-firsts.

Nokia Siemens Networks has inaugurated a TD-LTE Open Lab at its Chinese Hangzhou R&D facility. TD-LTE smartphone and terminal manufacturers will be able to use the lab to test the interoperability and functionality of their devices across TD-LTE networks.

"The development of terminals and devices has always been a bottleneck in the roll-out of new mobile technology," said Mr. Sha Yuejia, vice president of China Mobile. "We are thus more than happy to see that Nokia Siemens Networks has established a cutting-edge terminal testing environment, an initiative that we support wholeheartedly. After all, a healthy ecosystem needs efforts from all stakeholders."

Nokia Siemens Networks' Open Lab will provide an end-to-end testing environment for verifying the compatibility of terminals and devices with the company's TD-LTE network products and solutions. The lab will also provide consultancy and testing services to device manufacturers. Nokia Siemens Networks' TD-LTE R&D center in Hangzhou is fully integrated into the company's global network of LTE Centers of Competence.

Providing a live TD-LTE experience to operators in the region, Nokia Siemens Networks also recently kicked off a nationwide TD-LTE road show in China. Beginning in Beijing, the road show will cover more than ten provinces in three months, demonstrating the most advanced TD-LTE technology and applications.

In India, Even as the government hopes to raise around $9 billion from the 3G and BWA auctions, foreign telcos waiting in the wings are eager to unfurl a new technology — TD-LTE —which is akin to 4G technology.

US-based Qualcomm and Sweden's Ericcson aim to piggyback on TD-LTE, hoping that it will help them gain a toe-hold in India, the world's fastest growing mobile market. Qualcomm is to participate in the broadband wireless access (BWA) spectrum auction. If it does secure its bid in the auction, India could well become the first country after China to roll out TD-LTE.

TD-LTE, or Time Division Long Term Evolution, caters to peak download speeds of 100 Mbps on mobile phones, compared to the 20 Mbps for 3G and 40 Mbps for Wimax. LTE brings to the table additional spectrum, more capacity, lower cost, and is essential to take mobile broadband to the mass market.

The government has slotted the sale of two 2.3 GHz blocks of spectrum on April 11, providing 20 MHz spectrum in each of the country's 22 telecom circles. The base price has been set at $ 385 million. However, Qualcomm will need an Indian partner for its TD-LTE foray in the country since foreign direct investment is limited to 74%.

The US telco aims to use the 2.3 GHz spectrum band offered for TD-LTE-based BWA services. Sources in the know told TOI that the company would bid aggressively to corner one of the two BWA slots up for sale. There are 11 bidders for the BWA auction.

Asked to comment on the market dynamics, Sandeep Ladda, executive director, PricewaterhouseCoopers (PWC), said: "Though the Indian market is huge, it won't be smooth sailing post auction. We are adding 1 crore customers a month and in January, we added 1.9 crore customers, but the implementation of the new technology has its own cost. And India is a very cost conscious market."

Eager to play by the rules in India, Qualcomm has notified that it would enter into a joint venture with an Indian partner to launch its services and later exit from the joint venture after the network becomes operable.
Meanwhile, The WiMAX Forum has gone on the defensive during the WiMAX Forum Congress Asia in Taipei, Taiwan. The group is speeding up its time table to deliver the next generation of WiMAX--a reaction to heavy data use among WiMAX subscribers as well as the looming threat posed by Qualcomm and Ericsson's lobbying for TD-LTE in India.

Recently, the forum launched a global initiative to accelerate advanced WiMAX features that would double peak data rates and increase average and cell edge end user performance by 50 percent.

Mo Shakouri, vice president with the WiMAX Forum, said enhancements to the current generation of WiMAX weren't on the forum's roadmap, but were brought to the forefront at the urging of several WiMAX operators already facing capacity crunches. The forum reports that the average usage of data on WiMAX networks is close to 10 GB. Clearwire recently reported that mobile users average more than 7 GB of usage per month. In Russia, mobile WiMAX operator Yota sees more than 1 GB per month in data traffic from subscribers using its HTC smartphone. For laptops, it's 13 GB per month.

"Demand for data is moving so fast that we were pushed by many people to add this functionality," Shakouri said.

The WiMAX Forum has also been prodded to announce more detailed plans for 802.16m, and step up the timeline for its development via a new group called the WiMAX 2 Collaboration Initiative, which is made up of vendors Samsung, Alvarion, Motorola, ZTE, Sequans, Beceem, GCT Semiconductor and XRONet. The companies will work in tandem with the WiMAX Forum and WiMAX operators to accelerate the next-generation standard. WiMAX 2, the marketing name for the 802.16m standard, is expected to expand capacity to 300 Mbps peak rates via advances in antennas, channel stacking and frequency re-use.

The forum previously forecast 802.16m would hit in 2012 or 2013. But increasing demands for data--coupled with Qualcomm and Ericsson urging Indian mobile broadband license bidders to go with TD-LTE--motivated the forum to put some stakes in the ground and declare that WiMAX 2 equipment will meet certification by the end of 2011.

"There has been a lot of noise about TD-LTE, and the WiMAX Forum had not specifically given dates regarding timelines for 802.16m," Shakouri said. "Basically our announcement around 802.16m came about because of the noise in India."

The formation of the WiMAX 2 Collaboration Initiative is a marked change from the way the first generation of WiMAX was developed. Sprint Nextel was the entity driving the majority of the standards work as it was eager to get to market and begin building an ecosystem. Vendors are now taking the lead and driving equipment readiness before the 802.16m standard is finalized by the end of this year. Shakouri said the standard is 95 percent finished.

"Those companies are going to take a more active role inside the forum," Shakouri said. "They have all come together to speed up the process."

The group of vendors plans to collaborate on interoperability testing, performance benchmarking and application development before the WiMAX Forum establishes its certification program to narrow the gap between the finalized standard and commercial rollouts.
So how much of a threat is TD-LTE to WiMAX? Shakouri said the answer depends on spectrum decisions. "At this moment, the spectrum we are focusing on is separate, aside from what Qualcomm announced in India," Shakouri said. He also said that a TD-LTE ecosystem is at least two to three years behind WiMAX.

Many analysts speculate that TD-LTE will become the crossover technology that will prompt WiMAX operators to flip to LTE. Clearwire was part of a group of operators and vendors that last month asked the 3GPP standards body to begin working on specifications that would enable TD-LTE to be deployed in the 2.6 GHz band, which Clearwire uses for WiMAX. During the CTIA Wireless 2010 trade show last month, Clearwire CEO Bill Morrow reiterated the company's interest in deploying LTE when the technology catches up to WIMAX. He also called for one standard down the road.
Another initiative the forum is announcing this week is the launch of its Open Retail Initiative, a global program aimed at driving WiMAX into consumer devices sold directly or through retail channels that can be activated by the consumer over the air on the network. If you remember the evangelism of early WiMAX advocates like Barry West, this capability was supposed to be the Holy Grail of the technology.

Wednesday, 31 March 2010

Renewed focus on TD-LTE

Last year I blogged about the 3G Americas report on TD-LTE and Motorola's gamble on TD-LTE.





The following is from daily wireless blog:

Industry momentum behind Time Division LTE continues to grow with news that a number of major operators and vendors are working with the 3GPP to allow the standard to be deployed in the USA, using the 2.6GHz spectrum band. Clearwire and its partners own the majority of that spectrum. Most of Clear’s 2.6 GHz spectrum goes unused.

Light Reading Mobile notes that China Mobile, Clearwire, Sprint Nextel, Motorola, Huawei, Nokia Siemens Networks, Alcatel-Lucent and Cisco Systems are asking for the 2.6GHz spectrum (2496MHz to 2690MHz) to be defined as a TDD band for LTE.

Outside the United States, part of the band (2570MHz to 2620MHz) is already specified for TDD. The new work will extend this compliance. The report adds that specifications for the US 2.6GHz band for TD-LTE is scheduled to be completed by March 2011.

LTE pioneers TeliaSonera, NTT DoCoMo and Verizon Wireless, will all use different frequency bands for their respective LTE networks, explains TechWorld. So for roaming in the U.S, Japan and Europe to work, modems will have to support 700MHz, 2100MHz and 2600MHz, with more bands to be used in the future. That will be a challenge for roaming, says Light Reading.


The following is from fierce broadband wireless:

The appeal of TD-LTE has widened well beyond China. The recent announcement of Qualcomm to bid for TDD spectrum in India to support a TD-LTE deployment confirms--although it was not required to validate--the emergence of TD-LTE as global technology, likely to command a substantial market share.


Why the sudden interest in TD-LTE?

There are four main factors driving a growth in support for TD-LTE:

  • The FDD LTE and TD-LTE versions of the 3GPP standard are very similar. As a result, devices can support both the FDD and TDD interfaces through a single chipset--i.e., without any additional cost. This is a hugely important new development: TD-LTE will benefit from the wide availability of FDD LTE devices that will be able to support TD-LTE as well. Unlike WiMAX, TD-LTE does not need to prove to have a substantial market share to convince vendors to develop devices. Vendors do not need to develop new devices, they simply need to add TD-LTE support to the existing ones.
  • There is a lot of TDD spectrum available, and in most cases it is cheaper and under-utilized. 3G licenses frequently have TDD allocations and upcoming 2.5 GHz auction in most cases contemplate TDD bands.
  • The increasing availability of base stations that can be cost-effectively upgraded will make it possible and relatively inexpensive for WiMAX operators to transition to TD‑LTE using the same spectrum allocation. The transition will still require substantial efforts and be justified only in some cases, but it will make it easier for WiMAX operators to have roaming deals and to have access to the same devices that LTE operators have.
  • Industry commitment to WiMAX 16m, the ITU-Advanced version of WiMAX and successor to the current WiMAX 16e, is still limited.


What's next?

In the near term very little will change. TD-LTE is still being developed and it will take time before it gets deployed beyond core markets like China and possibly a few others like China. In Europe, for instance, mobile operators will deploy LTE in the FDD spectrum and only when they will need additional capacity they are likely to move to TDD. Unlike FDD LTE, TD-LTE will move from initial deployments in developing countries, with a later introduction as a mature technology in developed countries--a quite interesting trend reversal.


WiMAX operators will also be barely affected by TD-LTE in the short term. WiMAX is years ahead in terms of technological maturity, devices and ecosystem. This gives them a strong advantage in comparison to TD-LTE operators: They know the technology already, they have a network, and they have customers. They also have the choice whether to switch to TD-LTE or not--and, more importantly, they have no pressure to do so before TD-LTE has reached the maturity they feel comfortable with or until the WiMAX 16m prospects become clearer.



Monday, 11 January 2010

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

Picture Source: http://www.itu.int/dms_pub/itu-t/oth/21/05/T21050000010003PDFE.pdf

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.

TD-SCDMA STE

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.

TD-SCDMA LTE

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.

TD-SCDMA LTE+

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 (http://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_55b/Docs/R1-090133.zip).

For Wireless Relaying see the ZTE paper here (http://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_56b/Docs/R1-091423.zip).

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 (http://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_56b/Docs/R1-091655.zip).

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.

Sunday, 22 November 2009

Focus on TD-LTE by 3G Americas


3G Americas has published an educational white paper titled, "3GPP LTE for TDD Spectrum in the Americas". The report provides a top-level overview on the considerations for deployment of Long Term Evolution (LTE) in Time Division Duplex (TDD) technology spectrum in the Americas and recommends LTE TDD as a mobile broadband solution to utilize valuable TDD spectrum assets in the region.

The white paper explains the technical mechanism in which LTE TDD (also known as TD-LTE) and Time Division Synchronous Code Division Multiple Access (TD-SCDMA), a 3rd Generation Partnership Project (3GPP) third generation technology deployed in China, are smartly designed with the ability to operate together with great harmonization and efficiency. LTE TDD is a natural migration for TD-SCDMA operators. The technical synergy between LTE TDD and TD-SCDMA operators will thus increase the economies of scale for LTE TDD operators throughout the world.

Although operators are making plans for the deployment of LTE Frequency Division Duplex (FDD) technology, the white paper emphasizes that operators, regulators, license holders and investors must strongly consider the significant opportunities behind deployment of LTE in fragmented TDD spectrum as a mobile broadband solution that can serve the communication needs and demands of the marketplace.

Additionally, the report highlights that asmobile broadband is becoming ubiquitous throughout the Americas and the Internet generation is growing more accustomed to having broadband access everywhere, technology usage is exploding and, thus, is putting a tremendous strain on already well-utilized networks and spectrum. 3GPP LTE for TDD Spectrum in the Americas focuses on the LTE ecosystem and how operators are working to meet this increasing demand for mobile broadband services.

The LTE ecosystem supports both FDD and TDD operation, offering operators flexibility to match their existing networks, spectrum and business objectives for mobile broadband and multimedia services. Fifteen paired (for FDD operation) and eight unpaired (for TDD operation) spectrum bands have already been identified by the 3GPP for LTE. This means an operator can introduce LTE in new spectrum bands.

The white paper, 3GPP LTE for TDD Spectrum in the Americas, was written collaboratively by members of 3G Americas and is available for free download on the 3G Americas website at www.3gamericas.org.

The whitepaper is available here.

Tuesday, 17 November 2009

Motorola believes in TD-LTE


According to Fierce Broadband Wireless:

Motorola is being very strategic about the contracts it goes after, said Bruce Brda, senior vice president and general manager of the vendor's wireless networks business, in an interview with FierceBroadbandWireless.

"We are not trying to go head to head in every part of the globe. We've been selective in our engagements, focusing on the customers that we think we have a higher advantage with," Brda said. "Our initial thrust is in places in Asia where we have a significant competitive advantage." That's why it won an LTE contract with Japan's KDDI, he said, despite the fact 10 vendors in all competed for that business.

Motorola's other sweet spot is the TDD (unpaired spectrum) version of LTE, otherwise known as TD-LTE, a technology China Mobile is keen on deploying. Brda believes that Motorola's OFDM experience with WiMAX coupled with its TDD experience, again with WiMAX, will give Motorola an advantage in China.

TD-LTE, in fact, won't be a niche market, Brda said. "With the demand for data that exists around the world, it will be a solution set that solves the equation, not just FDD, but a series of solutions, and TD-LTE will play in increasingly large role, maybe coexisting in the same network as FDD LTE."


Brda noted that Motorola is talking to a number of European operators that envision TD-LTE and FDD LTE coexisting. "You could have one set of services carried over the TDD network and another set going over FDD," he said. "It's would create a more efficient use of the network, but I also think more and more TDD spectrum is going to be available. It's been kind of ignored around most of the world, but it's much easier to find un unpaired block of spectrum than a paired block."

Another aspect that has been largely ignored is the fact that experience in mobile WiMAX is highly transferable to the LTE world. Motorola, which has constructed about 20 WiMAX networks, and Samsung are now the two major vendors that have stuck with the mobile WiMAX game to a high degree. Many vendors such as Alcatel-Lucent, Ericsson and Nokia Siemens Networks either shunned mobile WiMAX or significantly scaled back on their efforts in favor of LTE.

Picture source: ChinaByte

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.