IPv6 Consideration in LTE

IPv6 Consideration in LTE

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Standards Developments in SAE

Standards Developments in SAE

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Coordinated Multi-Point (CoMP): Unresolved problems

I have blogged about CoMP in quite some detail in the past. Someone recently pointed out an interesting video from Fraunhofer Heinrich Hertz Institut which is embedded below:

CoMP may be not as practical as we may think. One of the things pointed out by Dr. Ariela Zeira, InterDigital's Vice-President of Advanced Air Interfaces in the LTE World Summit was that there exists a gap between the theoretical and the practical gains of CoMP.

She went on to suggest the following as way forward for the Coordinated Multipoint acceptance in future:

• Address root causes of gaps between academia and current feedback schemes
• Need for improved Channel State Information (CSI) feedback resolution
• Need for improved frequency domain precoding granularity
• Apply CoMP where most needed and/or theoretical gains can be approached
• Heterogeneous networks
• Interference problem is more severe than in macro-only deployment
• Especially for Femto Closed Subscriber Group and Pico Cells employing large cell extension
• Lower delay spread and low mobility can be expected in Femto and Pico cells and reduce performance loss from feedback impairments
• Relay Backhaul Channel (RBC)
• More accurate CSI feedback from stationary relay station is possible enabling advanced non-linear precoding schemes.
• High rank MIMO transmission will not be effective due to higher probability of Line of Sight (LOS) channel from Macro to Relay

CoMP is still probably the most promising spectral efficiency solution but need to focus on closing the gap between gains predicted by theory and those achievable with current LTE Release 8 Feedback Schemes

Interdigital's 'Fuzzy Cells' technology for cell edge performance improvement

Back in LTE World Summit 2010, I heard from Dr. Ariela Zeira, InterDigital's Vice-President of Advanced Air Interfaces about various things Interdigital have been working on.

One of the technologies that caught my attention was Fuzzy Cells technology to increase the cell edge rates. The following is from their press release for Mobile World Congress:

BARCELONA, Spain, Feb 15, 2010 (BUSINESS WIRE) -- InterDigital, Inc. today announced the demonstration of its "Fuzzy Cell" technology that improves cell-edge performance at the 2010 Mobile World Congress. The Fuzzy Cell technology is part of the company's comprehensive suite of "Next Generation Cellular" (NGC) innovations that combine advanced network topologies and spectrally-efficient air interface solutions for LTE-advanced and beyond.

"Many wireless operators and customers are experiencing a substantial degradation of service quality caused by the ever-growing demand for mobile data," said James J. Nolan, Executive Vice President, Research and Development, InterDigital. "We are at the forefront of developing solutions for more efficient wireless networks, a richer multimedia experience, and new mobile broadband capabilities that support operators to capture revenues from the boom in smartphones. The Fuzzy Cell fits nicely within our much broader efforts on spectrum optimization, cross-network connectivity and mobility, and intelligent data delivery techniques."

While cellular networks have become virtually ubiquitous, users continue to experience inconsistent and unpredictable performance when moving around. While this degradation is often the result of network congestion or an obstructed path of the radio waves, it is also inherent to traditional cellular deployments, whereby signals degrade towards the fringe of any given cell due to interference from neighboring cells. It is estimated that typical users experience this situation, known as being in the cell-edge, more than 50% of the time. Advancements in HSPA and LTE primarily increase peak data rates and only offer modest improvements in average performance throughout a cell.

Fuzzy Cells is a novel approach for leveraging existing resources to improve spectral efficiency and cell-edge performance. In a traditional deployment a device connects to one site at a time (even if multiple sub-bands are used at each site) and all sites use the same power levels and sector orientations for all sub-bands. In a Fuzzy Cell deployment, a device may connect to multiple sites at a time through the different sub-bands and continue to realize full system bandwidth. The power levels and sector orientations of the different sub-bands are optimized for best performance. In simpler terms, the device exploits the best combination of base station support regardless of its position, removing traditional limitations of cell or sector boundaries. Importantly, Fuzzy Cell technology can also allow gains indoors as it allows connection to more than one cell/sector at a time as available. The Fuzzy Cell technology provides additional improvement over Fractional Frequency Reuse (FFR) methods that are supported by current specifications.

The following shows the demonstration of Fuzzy cells:

I haven't heard any news recently on this technology but its an interesting concept, not sure if it would be adopted in the near term in the standards.

Open Radio Equipment Interface (ORI) for Efficient Basestation Deployment

Open radio equipment interface (ORI)

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Presented by Andreas Neubacher on behalf of NGMN Alliance at LTE World Summit Amsterdam, Netherlands May, 2010

LTE: Learning from the 3G experience

Interesting analysis from Matthew Bloxham from Deutsche Bank Telecoms Research in the LTE World Summit 2010.

Next Generation Wireless Enablers in 2020

Enabling Wireless Communication Future presented by Tim Watkins, Vice President Huawei West Europe Region on 18th May 2010 in LTE World Summit 2010

NTT DoCoMo: Core Network Evolution and Voice Strategy

Core network evolution and voice strategy

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Presentation by Seizo ONOE, Senior Vice President and Managing Director of R&D Strategy Department NTT DOCOMO, INC. in LTE World Summit 2010 on the 18th May 2010

Sisvel's LTE Patent Pool

One of the things I wanted to blog from the LTE World Summit was the new Patent Pool by Sisvel. In past I have blogged about the patent pool initiatives from Via Licensing Corp. and MPEG LLA LLC.

Based on Sisvel's presentation, they have the most number of companies in their pool which will make them the dominant pool and give the required clout to negotiate licensing fees.

The following is from PC World Magazine:

Typically, patent pools are managed by specialized companies that don't own intellectual property themselves. They set up licensing programs, collect license fees and distribute the proceeds to member companies. In the case of LTE, three of these -- Sisvel, Via Licensing and MPEG LA -- are vying to form a pool that represents a critical mass of LTE patents.

Sisvel, an Italian company that also operates a patent pool for MPEG audio technology, this week claimed it had brought together 32 significant LTE patent holders, the largest number of any of the three patent-pool companies. "With the kind of scale that we're talking about here ... the pool could really be close to a one-stop shop," said Sean Corey, IP counsel for Sisvel US.

Meanwhile, MPEG LA says about 15 companies are working with its pool program, but added that they include some of the major players in terms of patents and market share. "There's a critical mass there," said Bill Geary, vice president of business development at MPEG LA. Via Licensing says 24 patent holders were actively discussing licensing terms and conditions at its last meeting of stakeholders, he said.

Formation of the pools is still at an early stage, with none of them yet operating and no patent holders publicly announcing their affiliations. But while all three say they are months away from operation, Via claims it has the most aggressive program. After kicking it off in January, the company could get its patent pool running in as little as 12 months, said John Ehler, Via Licensing's director of wireless programs. MPEG LA has been working on its own pool for about two years and hopes to have it in operation next year, Geary said. Sisvel's Corey said it takes between 18 months and two years to get a program going.

All three companies want to have the biggest pool, to make it easy for vendors large and small to license everything they need. In this way, patent pooling should help to accelerate adoption of LTE, the patent-pool promoters said. It could also attract a broader range of companies, such as consumer electronics makers and embedded device manufacturers, to the fast networks.

Patent pools are likely to have a bigger impact on embedded devices than on smartphones, according to Robert Syputa, an analyst at research company Maravedis. The market for machine-to-machine radio devices such as smart electrical meters is more price-sensitive than for mobile data products that consumers use, he said. Easier licensing may also draw in a wider range of vendors of such products, he said.

It's important to get pools organized early in the adoption cycle of a technology, Syputa said. If the commercial marketplace advances too far, too much intellectual property may become locked up in one-on-one licensing agreements between companies, he said. This happened with 3G, but with LTE, patent holders still have time to do it right, he said.

At least one important LTE patent holder, Ericsson, has said it will only sign bilateral license deals. Having three pool efforts in progress seems to complicate matters where just a single sanctioned one might be preferable, Syputa said. But even three pools would be preferable to a series of individual agreements, he said.

The IPR battle is not simple and straightforward as mentioned above. The following is from Daily Wireless Blog:

Qualcomm and its GSM technology counterpart InterDigital together control 40% of the LTE patent pool, with 19% and 21% of total patents, respectively, says Informa. Most LTE supporters want the royalty bill to be a one percentage of the sale price in an LTE handset, but IPR owners appear to be pushing it closer to 5% – similar to Qualcomm’s IPR tab.

Ericsson, the world’s largest wireless infrastructure manufacturer, claims to have 25 percent of the essential patents to Long Term Evolution (LTE) networks, making the vendor the single largest IPR hold in LTE. Most of the huge IPR holders in W-CDMA – Qualcomm, Nokia, Ericsson and InterDigital – are also claiming a big share of the LTE patent base.

Ericsson claims contradict a survey from Informa regarding essential IPR holders. Informa estimates Ericsson is much lower in the IPR ranking, behind Qualcomm, InterDigital, Samsung and Huawei in total patents, with emerging vendors such as Huawei also contributing 4G development research.

Ericsson believes it holds nearly 24 percent of awarded essential patents for LTE. Informa estimated that Ericsson holds about 7 percent.

Unlike Qualcomm – which by almost everyone’s calculations remains the leader in essential IPR – Ericsson is favouring a patent pool approach, which would set the total royalty rate for combined patents at under 10%, says Caroline Gabriel.

You may also want to check this (nearly) latest presentation from Alex Lee on LTE patents, embedded below:

LTE Patents for Commercial Products 2Q 2010

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VoLGA and VoLTE Architecture difference

Self explanatory slide from NTT DoCoMo presentation in the LTE World Summit.

LTE HeNB Options

In my earlier post I had a picture of LTE Home eNodeB architecture. There is a possibility of multiple ways in which Home eNodeB can be connected. A slide from Andy Goddards presentation in LTE world summit summarises the different approaches.

Femtocell configuration via TR-069

TR-069 has been standardised for remote Configuration Management. The slide above is from a presentation by Andy Gothard in Femto Forum. The presentation below sheds more light on TR-069 for Femtocells.

Extending TR-069 Management to Femtocell

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'Greater' Femtocells

An interesting slide from the presentation by Prof. Simon Saunders, Chairman of Femto Forum in LTE World Summit. The slide throws more light on the Greater-femtocells I blogged about last year.

Related Post: When Femtocells become Picocell.

Conformance, Interoperability and Field testing via GCF

Delivering a “Test Once, Use Anywhere” Certification Scheme for LTE Devices

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Relationship between frequency & capacity, in-building penetration & cell size

Interesting picture from a presentation by Prof Ed Candy Hutchison Whampoa Europe & 3 Group Europe in the LTE World Summit.

Voice over LTE - GSMA Presentation

Voice over LTE

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Running live networks on Renewable Energy sources

We have been hearing for years that Solar energy could be used to run remote BTS/Node B so i was glad to see that they are deployed in practise and are working well. It was very interesting to see hear Pradeep de Almeida, Group Chief Technology Officer, Dialog Telekom Plc, Sri Lanka in the LTE World Summit.

The picture above lists the features from an ideal renewable energy powered BTS or Node B (or eNodeB for that matter). The picture below shows one of the real life deployments in Sri Lanka.

It was very interesting to hear that the power generated using the Solar and Wind approach is generally in surplus and this extra energy could be sold to the power companies or can be used to provide an outlet point where the people can come and charge their phones.

The return of investment (ROI) for these kind of deployments could be as low as 2 years and can be as high as 4 years. The time for ROI will be reduced for countries where diesel (used for generators) is expensive and will be increased when diesel is cheap. That is why we may not find environmently friendly approaches in Middle East for quite some time because of cheap oil.

You can read more about the Dialog Telekom green energy initiative here and here.

ZTE shows off its green credentials

ZTE has long been focussing on green(er) network and recycling. They launched their new generation 'green base stations back in 2006. They have also been recently cited for their energy saving technology. They also have a solar powered phone which is unfortunately not available in UK. Their Omni-RAN network can help reduce the OPEX by two thirds. Their focus has not only been on Mobile phones and networks but on the fixed lines as well.

So it was not at all surprising to hear Xiaodong Zhu, CTO of ZTE European marketing in the LTE World Summit talking about the end to end green networks. Green technology is not only helpful to for the 'green credentials' but it can also help reduce Opex which can help recover any additional investments (if any).

More manufacturers will hopefully follow the lead.

ng-connect LTE car from ALU

Back in the LTE World Summit 2010 there was this ng-connect LTE car demo. I wasn't able to get a demo as there didnt seem to be anyone willing to be filmed for the blog. The first I heard about this ng.connect program was last year when I blogged about the case for early LTE in USA.

The ng connect program ecosystem brings together lots of companies that are collaborating from research to sales and marketing. If you click in the picture above you will be able to see the enlarged image and at the bottom you can see the names of these companies. The car is ofcourse Toyota but I wasnt able to see that in the list of companies.

The following Youtube clip gives an introduction to the connected car

The following is from the Demo from France. In January 2010, Alcatel-Lucent launched for the first time in Europe the ng Connect LTE Connected Car in its Velizy, France facility, showcasing the capabilities that Long Term Evolution (LTE), the next generation of mobile networks, will bring to automakers, service providers, application developers and end users. Also demo'd in Velizy was the live LTE drive tour in a van, testing mobile services on a campus-wide network, demonstrating a smooth transition between 3G/HSPA and LTE networks.

The final video is slightly longer clip which shows the thought process behind the connected car.

If you havent had enough already then I would also recommend this post.

UMTS/HSPA State Transition Problems to be solved with LTE

The way UMTS/HSPA is designed is that the Mobile (UE) is always in IDLE state. If there is some data that needs to be transferred then the UE moves to CELL_DCH. If the amount of data is very less then the UE could move to CELL_FACH state. The UE can also move to CELL_PCH and URA PCH if required but may not necessarily do so if the operator has not configured those states.

The problem in UMTS/HSPA is that these state transitions take quite some time (in mobile terms) and can slow down the browsing experience. Martin has blogged about the state transition problems because of the keep alive messages used by the Apps. These small data transfers dont let the UE go in the IDLE state. If they do then whole raft of signalling has to occur again for the UE to go to CELL_FACH or CELL_DCH. In another post Martin also pointed out the sluggishness caused by the UE in CELL_FACH state.


Mike Thelander of the Signals Research Group presented similar story in the recently concluded LTE World Summit. It can be seen from the figure above that moving from IDLE to CELL_DCH is 1-3secs whereas FACH to DCH is 500ms.

In case if some Apps are running in the background, they can be using these keep alive messages or background messages which may be very useful on the PC but for the Mobiles, these could cause unnecessary state transitions which means lots of signalling overhead.

The Apps creators have realised this problem and are working with the Phone manufacturers to optimise their messaging. For example in case of some Apps on mobiles the keep alive message has been changed from 20 seconds to 5 mins.

3GPP also realised this problem quite a while back and for this reason in Release-7 two new features were added in HSPA+. One was Continuous Packet Connectivity (CPC) and the other was Enhanced CELL_FACH. In Release-8 for HSPA+, these features were added in UL direction as well. The sole aim of these features were to reduce the time it would take to transit to CELL_DCH. Since CPC increases the cell capacity as well, more users can now be put in CELL_FACH instead of being sent to IDLE.

An interesting thing in case of LTE is that the RRC states have been simplified to just two states as shown here. The states are IDLE and CONNECTED. The intention for LTE is that all the users can be left in the CONNECTED state and so unnecessary signalling and time spent on transitioning can be reduced.

The preliminary results from the trials (as can also be seen from here) that were discussed in the LTE World Summit clearly show that LTE leads to a capacity increase by 4 times (in the same BW) and also allow very low latency. I am sure that enough tests with real life applications like Skype, Fring and Yahoo IM have not been done but I am hopeful of the positive outcome.