Wednesday, 20 January 2010

LG cementing its LTE handset leader position

LG has been in news recently for showing off their LTE preparedness:


LG Electronics MobileComm U.S.A., Inc. revealed at this year’s CES the advanced capabilities of Long Term Evolution or LTE technology. The company showcased LTE download speeds of 100MBps. Long Term Evolution is also known as the next generation mobile communication service technology.

LG conducted real-time demonstrations of video conferences, full HD video files and web-surfing at speeds up to 50Mbps for uploads and 100Mbps for downloads. All this was executed by connecting to the LTE USB Modem from LG. The offering gives extremely high data download speeds.

The company also unfurled to the CES attendees the ‘handover’ technology. This offering executes hindrance-free network conversion between LTE and CDMA networks. LG displayed endless data transmissions taking place between LTE and CDMA antennas which enables video file downloads, internet calling and web surfing. All this was done via the sleek version of the 4G LTE device which is an LG proprietary product fashioned for the Handover just last August.

LG has also teamed up with Verizon wireless to demonstrate the applications and capabilities that are possible with LTE networks. At the recently held event, the Verizon Wireless Innovation Center demonstrated many applications with Innovation Center member LG Mobile Phones being its main participant.

LG demonstrated LTE network and joined forces with other companies for formulating Home monitoring solutions, an indoor/outdoor IP security camera and a video conferencing product.

Alcatel-Lucent and LG Electronics have completed a successful handoff of an end-to-end data call between Long Term Evolution, or “LTE,” and CDMA mobile networks. The live, over-the-air handover consisted of an uninterrupted streaming video session conducted over Alcatel-Lucent's end-to-end commercial LTE and CDMA/EV-DO infrastructure using an LG Electronics CDMA and LTE dual mode device.

The handoff is compliant with the standards established by the Third Generation Partnership Project, or “3GPP.” According to Ken Wirth, president of 4G and LTE Networks at Alcatel-Lucent, since existing networks were designed primarily with voice in mind, the current explosion in data traffic is creating a challenge for service providers. The successful handoff demonstrates Alcatel-Lucent's readiness to deliver LTE to CDMA operators. LTE provides operators with the opportunity to deploy a system designed specifically to support data.

LG's M13 CDMA/LTE device incorporated for the testing is the world's first modem chipset for 4G LTE devices. It was created with commercial grade components and released in December 2008. The technology behind LG's M13 CDMA/LTE terminal is important in enabling LTE networks to operate transparently with existing CDMA networks.
According to In-kyung Kim, vice president of 4G development at LG Electronics Mobile Communications Company R&D Center, LG's M13 terminal will be an important device in enabling CDMA network operators to deploy a LTE network incrementally over a national CDMA network.

An article in Fierce Broadband Wireless summarises their leadership in these words:

LG has an impressive LTE track record: an LTE demo at Mobile World Congress 2008; the announcement of the world's first LTE chipset and modem prototype in November 2008; the first LTE-enabled mobile device Live Air Demo at Mobile World Congress 2009; the first FCC LTE Device certification built around LG's LTE chipset in June 2009; the first dual-mode LTE/eHRPD in-call handover in August 2009; and a 100 Mbps maximum throughput Live Demo at CES 2010.

3GPP Release8 June 2009 compliance, multiple band support (2.1 GHz Band1 or 700 MHz Band13), various system bandwidth, from 5 MHz to 20 MHz and max throughput with up to 100 Mbps downlink and 50 Mbps uplink, are among the main features supported by the dual-mode LTE/CDMA Vd13 device and LTE-only LD100U device.


In Las Vegas, LG executives recognized that the two devices recently unveiled are intended more to demonstrate their LTE development leadership and, likely, will not be launched as commercial devices. Although they didn't outline their exact plan, they disclosed that their own LTE modem will eventually be integrated into a netbook or notebook, meaning that a more integrated chipset solution will hit the market soon.


Known for its 2G and 3G handset line, LG relied on mature merchant chipset solutions such as Qualcomm, ST-Ericsson or Infineon chips, not LG technology. We can elaborate different scenarios to explain their new positioning as an LTE market driver. Gaining ground in all cellular technologies and capturing more than 10 percent of the total handset market as year-end 2009, leading them to third position worldwide, LG has decided to invest significantly into chipset development in order to become technology independent.


On top of the LTE modem, they will now introduce phones based on their own 2G/3G/4G intellectual properties to save cost and stay ahead. We could also speculate that LG wants to broaden their essential patents portfolio, driving 3GPP groups and initiatives to better compete with their current chip suppliers. In this case, once the LTE market matures and reaches a critical mass, LG will switch to third party players just as they have in the past. One more scenario has to be considered: following Nokia's early strategy, LG could license its LTE modem IP to partners that will manufacture the chipset solution and sell it back to them.


It's difficult to predict LG's long-term strategy in terms of chipset development at this point. The company has the scale to succeed, scale that small WiMAX players who recently announced parallel WiMAX/LTE roadmaps lack. In the new research report released by Maravedis in partnership with Reveal Wireless, entitled "WiMAX Wave2 Subscriber Station Chipset Vendors Competitive Analysis," we have identified the WiMAX chipset companies who have shifted to LTE by offering a flexible programmable base-band solution.


The LTE base-band chipset market is already crowded: incumbent manufacturers who ship in large volume (Qualcomm, ST-Ericsson, and Nokia), new entrants who traditionally relied on merchant solutions (LG and Samsung Electronics), and newcomers who leverage their OFDM expertise, WiMAX chipset background, and WiMAX ecosystem experience (Altair, Comsys, Sandbridge, Sequans and Wavesat) are committed to playing a significant role in the LTE baseband landscape. With Mediatek, Infineon, Marvell, and likely giant Intel poised to enter the market eventually, the field will soon be comparable to the aisles of CES 2010... very packed.


One thing I have learned is that initial leadership doesn't guarantee final outcome but we have to appreciate LG's rise in the LTE technology arena.

Tuesday, 19 January 2010

World Largest Operator helping transform China


Chinese operators have been spending Billions of Dollars building their 3G Infrastructure

China Mobile, the largest wireless carrier in the world with roughly 518 million customers, recently revealed that it has so far invested approximately RMB80 billion (US$11.7 billion) for 3G network construction. The carrier has completed the third phase of the 3G network (based on the home-grown TD-SCDMA standard) deployment in 2009 having covered approximately 70% of the Chinese cities.

The Chinese are becoming more and more mobile savvy.

In a news release Friday, China Internet Network Information Center (CNNIC) announced that China's mobile phone Internet users reached 233 million in December 2009, a growth of 120 million users from 2008. Among these users, 30.7 million accessed the Internet exclusively on their mobile phones.

China's online population reached 384 million as of December 2009, growing 28.9 percent from figures recorded in 2008, said CNNIC in the report.

The country surpassed the United States in 2008 to become home to the world's largest Internet user community.

There is a very interesting piece in The Guardian:


Until just over a year ago, Gong Kangshun spent much of his life trekking over the mountains around his remote village in south-west China. It isn't easy to make a living in Xiuxi, a tiny settlement of 58 families deep in Aba county, Sichuan. Gong grows crops on a small plot and sells rare fungi found on the steep slopes nearby. Many young people, including his brother, leave to find work in the factories and shops of China's east.
But a single purchase has shortened his working hours and sent his income soaring – by helping him to find buyers for his fungi. It has even improved his relationships with family and friends. "I'd panic without my mobile phone," the 35-year-old admits.
Across China, tens of millions have similar tales to tell. Many had never enjoyed phone access until recently. Now, for as little as £20, they can buy a handset, slot in a pre-paid sim card, start calling – and change their lives.
Most, like Gong, can thank one firm: China Mobile. With more than 70% of the domestic market it has 518 million subscribers; more than any other mobile carrier on the planet.
It is the world's largest phone operator by market value and the largest Chinese company listed overseas. Its work on 4G technology and its interest in foreign acquisitions suggest its international profile may soon grow.
Already the company's influence is rippling out across the world, almost unnoticed. The rapid spread of mobiles facilitated by the company's high-speed network roll-out, is both a product of China's aggressive development and a contributor to it – accelerating the pace of life and business, shrinking distances.
Some activists are enthusiastic about the potential for mobiles and the internet to expand the flow of information in a country with heavy censorship. They point to cases where camera phones have captured and shared images of unrest or official abuse.
The authorities certainly seem to be aware of the potential – Chinese social networking sites are strictly controlled and overseas services such as YouTube are blocked. In restive Xinjiang text messaging was turned off after vicious ethnic violence. The authorities also use mobiles for everything from political education to monitoring individuals.
The social and political effects of new technology are rarely straightforward, but for most people, mobiles are simply a part of their life. Whether a highly-paid Shanghai executive, or an independent farmer-cum-trader such as Gong, no one can afford to be without a phone – or a signal. China Mobile's 500,000 base stations now cover 98% of the population. You can call home from city subway trains, distant fields, or the peak of Mount Everest.
"If you have a requirement, we will have coverage," pledged the firm's chairman and chief executive Wang Jianzhou, who has more than three decades of experience in the sector.
"When we started this business we thought very few people would usemobile phones – only the rich," he said. Now he is dissatisfied with a penetration rate of 57%. "I think every adult should have at least one mobile … they are an extension of human ears, eyes and mouths."
Before the network reached Xiuxi, in late 2008, Gong used the phone perhaps twice a month. Each time he would walk for an hour to the nearest landline to call traders interested in buying the valuable "caterpillar" and "sheep stomach" fungi used in Chinese medicine.
"Now, on a busy day, I might make 20 calls," he said. "I can contact buyers in Chengdu and Shanghai. I can do business sitting at home and buyers can reach me, too."
His income has risen 50%, to 20,000 yuan (£1,820). And instead of walking seven hours a day to find the fungi collectors, he can call and ask them to deliver.
In his spare time, he chats to his younger brother, a chef in Zhejiang province who comes home at most once a year. Villagers hear a lot more news from the outside world these days – even Gong's 14-year-old son has his own phone. In 1997, there were just 10 million mobile users in China; by 2005, China Mobile had 240 million. Since then it has more than doubled.
The government pushes all carriers to serve the poorest. But since taking charge at China Mobile in 2004, Wang has shown sceptics that focusing on rural areas is a viable business strategy.
"Many analysts and investment bankers told me: never go to rural areas because they are low revenue. You will not make a profit," Wang said, in an interview at his spacious but low-key office in the company's headquarters on Beijing's Financial Street.
"I didn't believe that … with fixed lines, providing rural services is very, very difficult and expensive. [We have] low average revenue per user – but also low costs."
With a penetration rate of just 37%, there is plenty of room for growth among China's 700 million rural population. And there is plenty of demand. In Yangcun county, close to Beijing, Chen Fengmei anxiously scrolls through her latest text message: advice from officials on how the day's weather will affect her tomato crop. Another villager, Li Chunyu, checks the latest market prices for his pigs, no longer needing to trust middlemen or to give them a cut of his profits. "I never need to go anywhere. I can stay on the farm and find out everything," he said.
Continue reading the complete article here.

Monday, 18 January 2010

Top 10 paid iPhone apps


Interesting collection of paid iPhone Apps from The Independent.

1. Doodle Jump: £0.59 Jumping game featuring different platforms and obstacles to overcome.
See here for details. Official website here.


2. Where's Wally (Where's Waldo in USA). £1.79 The striped-jumper sporting explorer leaves the page and enters the iPhone in this hidden-object game.
More details here. Official website here.


3. MOTO X MAYHEM £0.59 Jump, lean and race through 14 levels of motocross action in this side-scroller.
More details here. Official website here.

4. CRASH BANDICOOT £1.79 High-octane 3D kart racing.
More details here. Official website here.

5. BEJEWELED 2 £1.79 The simple but compelling gem-swapping action puzzle.
More details here. Official website here.


6. WHO WANTS TO BE A MILLIONAIRE? £2.99 Although you can't win the ultimate cash prize, this game lets you experience the 'Millionaire' quiz questions.
More details here. Official website here.

7. THE SIMPSONS ARCADE £2.99 Help Homer round up the delicious doughnuts that are located around Springfield.
More details here.

8. TETRIS £1.79 The block-dropping classic.
More details here. Official website here.

9. NEED FOR SPEED SHIFT £3.99 With 20 supercars and 18 tricky tracks to master, this title, currently reduced, is a winner.
More details here.

10. IVIDEO CAMERA £0.59 No 3GS? No worries with this video camera app.
More details here.

Sunday, 17 January 2010

Mobile Phones transforming Africa

Interesting article from The Guardian:

The mobile phone is turning into Africa's silver bullet. Bone-rattling roads, inaccessible internet, unavailable banks, unaffordable teachers, unmet medical need – applications designed to bridge one or more of these gaps are beginning to transform the lives of millions of Africans, and Asians, often in a way that, rather than relying on international aid, promotes small-scale entrepreneurship.

While access to a fixed landline has remained static for a decade, access to a mobile phone in Africa has soared fivefold in the past five years. Here, in one of the poorest parts of the globe, nearly one in three people can make or receive a phone call. In Uganda, almost one in four has their own handset and far more can reach a "village phone", an early and successful microfinance initiative supported by the Grameen foundation.

One recent piece of research revealed how phone sharing, and the facility for phone charging, has been an engine of this small-business revolution. Particularly in rural areas, a small investment in a phone can first create a business opportunity, then maximise its reach by overcoming the possible limitations of real or technological illiteracy – because the phone operator can make sure the call gets through, and can cut off the call at exactly the right moment to avoid wasting any part of a unit. And what a difference a phone call can make.

Often the mere fact of being able to speak to someone too far away to meet with easily can be a transforming experience. For fishermen deciding which market is best for their catch, or what the market wants them to fish for, a phone call makes the difference between a good return on the right catch or having to throw away the profit, and the fish, from a wrong catch. For smallholders trying to decide when or where to sell, a single phone call can be an equally profitable experience.

But establishing market conditions is just the start. Uganda has pioneered cash transfers by phone through the innovative Me2U airtime sharing service, which allows a client to pay in cash where they are and transmit it by phone to family or a business associate hundreds of miles away. They receive a unique code that they can take to a local payment outlet to turn into cash.

But the market leaders are M-PESA, a mobile money system set up by Safaricom, in its turn an affiliate of Vodafone, in Kenya (although it operates in Uganda now too). Less than three years old, it has 7 million customers and, according to some sources, processes as much as 10% of Kenya's GDP.

At a recent International Telecommunications Union session, Nokia's Teppo Paavola pointed out that there are 4 billion mobile phone users and only 1.6 billion bank accounts. The huge scope for providing financial services through mobile phones represented by that differential is a tempting prospect for the big players.

But, as one British contender, Masabi, has discovered, it is one thing to develop a secure mobile payment system like their Street Vendor - which works on old handsets and in most scripts – and quite another to get a deal with the international financial regulators that police cross-border cash flows.

Masabi has worked with another UK company, Kiwanja.net, that aims to help NGOs and other not-for-profit organisations use mobile technology.

Ken Banks, founder of Kiwanja.net (Kiwanja means "earth" in Swahili) has pioneered a two-way texting system called FrontlineSMS that allows mass texting from a single computer-based source to which individual subscribers can reply.

So for example, health workers attached to a hospital in Malawi can "talk" to their base to seek advice, pass on news of patients' progress or ask for drug supplies. The data can be centrally collected and managed. All that's needed is a mobile signal – far more available than an internet connection.

FrontlineSMS is a free download: the aim is not to tell users what to do, but to help them work out how to apply the technology to their own problem.

The only barrier to even greater mobile use, apart from international financial regulations, are the taxes levied by national governments that can make the cost prohibitive. According to one recent report, despite exponential growth in countries like Uganda there is growing evidence that what for millions is a life-changing technology risks leaving out the poorest.


Friday, 15 January 2010

2.6 GHz LTE Spectrum Band Report


The licensing of the 2.6 GHz band will be critical to unlocking the benefits of global scale economies in the Mobile Broadband market, according to a new report* by US-based research firm Global View Partners in partnership with the GSMA. The research found that the 2.6 GHz spectrum, which has been identified globally by the ITU as the ‘3G extension band’, will be vital in satisfying the demand for greater capacity for Mobile Broadband and launching next-generation networks such as LTE, which will start to be deployed commercially around the world this year.

“There is clear evidence that the volume of data flowing over mobile networks is growing rapidly and is being accelerated by the popularity of smart phones and the growth in music and video downloads,” said Tom Phillips, Chief Regulatory Affairs Officer at the GSMA. “The report highlights that the 2.6 GHz band will allow operators to address rapidly increasing traffic volumes in an efficient and harmonised way. Recent licensing of this band in Hong Kong, Norway, Finland and Sweden, for example, has highlighted that there is more demand for paired (FDD) than unpaired spectrum (TDD) and that the ITU’s recommended Option 1** plan is the best structure to stimulate market growth in a technology-neutral and competitive environment.”

In Europe, measurable progress has been achieved towards the allocation of the 2.6 GHz frequency, as specified in the ITU Option 1 plan. There is widespread agreement at the member state and European Union level that this objective will best be fulfilled in a manner that is harmonised and coordinated across all countries in the region. The research suggests that leaving the band unstructured for auctions or with a diverse mix of non-harmonised FDD and TDD allocations should be avoided. Potential challenges include interference management, resulting reductions in usable bandwidth and loss of coverage in border regions, as well as higher costs and delayed equipment availability.

The research also points out that in many cases, the 2.6 GHz frequency will be the first opportunity for mobile operators to acquire 2x20 MHz of contiguous spectrum, enabling them to operate high-speed LTE services at optimum performance. LTE is the next-generation Mobile Broadband technology for both GSM and CDMA operators, and will leverage new and wider bandwidths to significantly increase data capacity in high demand zones such as dense urban areas. The 2.6 GHz spectrum is the ideal complement to the 700 MHz spectrum, also known as ‘digital dividend’, and will enable the most cost-effective nationwide coverage of Mobile Broadband across both rural and urban environments.

Governments in most Western European countries as well as in Brazil, Chile, Colombia, and South Africa are planning to award 2.6 GHz frequencies within the next two years.

The Report is available HERE.

Thursday, 14 January 2010

Temporary Identities in LTE/SAE - 2: RNTI's

Last year I covered some information on temporary identities but never got a chance to continue on it. Here is one on RNTI's

RNTI or Radio Network Temporary Identifier(s) are used primarily by eNB Physical Layer for scrambling the coded bits in each of the code words to be transmitted on the physical channel. This scrambling process in PHY happens before modulation. There is a sequence followed for scrambling, calculation of which depends on the RNTI(UE specific for channels like PDSCH,PUSCH) and cell specific (for broadcast channels like PBCH). Details could be found in [2].

The following table lists different kinds of RNTI's:

Lets look at some of these in slightly more detail:

P-RNTI (Paging RNTI): To receive paging messages from E-UTRAN, UEs in idle mode monitor the PDCCH channel for P-RNTI value used to indicate paging. If the terminal detects a group identity used for paging (the P-RNTI) when it wakes up, it will process the corresponding downlink paging message transmitted on the PCH.

SI-RNTI (System Information RNTI): The presence of system information on DL-SCH in a subframe is indicated by the transmission of a corresponding PDCCH marked with a special System Information RNTI (SI-RNTI). Similar to the PDCCH providing the scheduling assignment for ‘ normal ’ DL-SCH transmission, this PDCCH also indicates the transport format and physical resource (set of resource blocks) used for the system-information transmission.

M-RNTI (MBMS RNTI): Used in Rel-9 for MCCH Information change notification.

RA-RNTI (Random Access RNTI): The RA-RNTI is used on the PDCCH when Random Access Response (RAR) messages are transmitted. It unambiguously identifies which time-frequency resource was utilized by the UE to transmit the Random Access preamble. If multiple UEs had collided by selecting the same signature in the same preamble time-frequency resource, they would each receive the RAR.

C-RNTI (Cell RNTI): The C-RNTI to be used by a given UE while it is in a particular cell. C-RNTI allocation and details are too complex to explain in the blog so please refer to Nomor newsletter here.

TC-RNTI: When the UE does not have allocated C-RNTI then Temporaru C-RNTI is used. A temporary identity, the TC-RNTI, used for further communication between the terminal and the network. If the communication is successful then TC-RNTI is promoted eventually to C-RNTI in the case of UE not having a C-RNTI.

SPS-C-RNTI (Semi-Persistent Scheduling C-RNTI): For the configuration or reconfiguration of a persistent schedule, RRC signalling indicates the resource allocation interval at which the radio resources are periodically assigned. Specific transmission resource allocations in the frequency domain, and transmission attributes such as the modulation and coding scheme, are signalled using the PDCCH. The actual transmission timing of the PDCCH messages is used as the reference timing to which the resource allocation interval applies. When the PDCCH is used to configure or reconfigure a persistent schedule, it is necessary to distinguish the scheduling messages which apply to a persistent schedule from those used for dynamic scheduling. For this purpose, a special identity is used, known as the Semi-Persistent Scheduling C-RNTI (SPS-C-RNTI), which for each UE is different from C-RNTI used for dynamic scheduling messages. - Source: LTE, The UMTS Long Term Evolution: From Theory to Practice By Stefania Sesia, Issam Toufik, Matthew Baker

TPC-PUCCH-RNTI (Transmit Power Control-Physical Uplink Control Channel-RNTI) and TPC-PUSCH-RNTI (Transmit Power Control-Physical Uplink Shared Channel-RNTI): The power-control message is directed to a group of terminals using an RNTI specific for that group. Each terminal can be allocated two power-control RNTIs, one for PUCCH power control and the other for PUSCH power control. Although the power control RNTIs are common to a group of terminals, each terminal is informed through RRC signaling which bit(s) in the DCI message it should follow.

The following table lists the values that are assigned to different RNTI's in MAC:



[1] 3GPP TS 36.321 - Evolved Universal Terrestrial Radio Access (E-UTRA) Medium Access Control (MAC) protocol specification
[2] 3GPP TS 36.211 - Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation

Wednesday, 13 January 2010

Takehiro Nakamura on LTE Radio Aspects


In summary:

Release 8 - Minor change requests to it based on March 2009 freeze;
Release 9 - an enhanced version of Release 8 and additional features;
Release 10 (LTE-Advanced) - proposed as an IMT-Advanced and is expected to be approved by December 2010; major differences between LTE and LTE-Advanced


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.