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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.

Huawei's "Two Cloud" solution for Mobile Broadband

In case you are a regular and noticed my recycled image for this post then let me tell you that the post is about recycled ideas ;)

It is a well known fact that I have mentioned at various places in the blog as well that the higher the frequencies, the smaller the cell radius. Since we know that the common deployment frequencies for LTE would be around 2.6GHz then the signal penetration through walls may not be great.

As a result we will be forced to use Hierarchical cells that would allow load balancing and also higher speeds as the smaller cell sizes translate to fewer users and interference.

The following is from Huawei's website:

Based on our roadmap of early success in mobile and fixed broadband network construction, Huawei now responds to the mobile broadband dilemma facing global operators with the unique "Two Clouds" solution.

Employing optimal topologies for access networks providing DSL-level bandwidth for users across the board, the two clouds work together to deliver the most cost-effective means of enhancing user experiences.

• A high speed cloud, consisting of Pico and AP BTSs, is typically deployed in densely-populated urban areas to deliver an average bandwidth of 2 Mb/s.
• A continuous cloud of macro BTSs is applied for wide coverage delivering a bandwidth of 256 to 512 kb/s.

Huawei's "Two Clouds" model allows operators to profitably deploy mobile broadband networks while utilizing an intelligent site management framework to automatically adjust bandwidth and reducing construction, operation, and maintenance costs.

Incorporating this framework, flexible network mapping permits manageable, controllable mobile broadband networks, ensuring continuous network coverage in various scenarios, and provides users with inexpensive, quality broadband services. Very convincingly, Huawei's "Two Clouds" concept can reduce the cost per bit by as much as 70%.

One can guess that Self Organizing Networks would play important part in realising this in practice.

Story Source: Think Femtocell

Dilbert Humour: So why is it called 4G?

 

Source: Dilbert 

E-UTRAN Mobility Drivers and Limitations

Many years back, when things used to be simple, I wrote a tutorial about Handovers in UMTS. It would be very difficult to write a similarly simple tutorial for LTE. Things are a bit complicated because there are many different conditions in which handovers can take place.

It was also easier to visualise the Intra-frequency and Inter-frequency handovers in UMTS and you can probably do the same to some extent in LTE but with things getting more complicated and carrier aggregation, classifying handovers in these categories may be difficult.

3GPP TS 36.300 has an informative Annex E which details the scenarios in which handovers and cell change can/will take place.

It is best to go and see Annex E in detail. Here is a bit of summary from there:

Intra-frequency mobility: intra-frequency mobility is the most fundamental, indispensable, and frequent scenario. With the frequency reuse being one in E-UTRAN, applying any driver other than the “best radio condition” to intra-frequency mobility control incur increased interference and hence degraded performance.

Inter-frequency mobility: as in UTRAN, an operator may have multiple carriers/bands for E-UTRAN working in parallel. The use of these frequency layers may be diverse. For example, some of these frequency layers may utilise the same eNB sites and antenna locations (i.e., co-located configuration), whereas some may be used to form a hierarchical cell structure (HCS), or even be used for private networks. Some frequency layers may provide MBMS services, while some may not. Moreover, E-UTRAN carriers/bands may be extended in the future to increase capacity.

Inter-RAT mobility: the aspects that need to be considered for inter-RAT are similar to those for inter-frequency. For mobility solutions to be complete with the inter-RAT drivers, relevant updates would be necessary on the legacy (UTRAN/GERAN) specifications. This will add to the limitations, which are evidently more effective in inter-RAT.


The drivers for mobility control are:

Best radio condition: The primary purpose of cell reselection, regardless of intra-frequency, inter-frequency, or inter-RAT, is to ensure that the UE camps on/connects to the best cell in terms of radio condition, e.g., path loss, received reference symbol power, or received reference symbol Es/I0. The UE should support measurements to suffice this aspect.

Camp load balancing: This is to distribute idle state UEs among the available bands/carriers/RATs, such that upon activation, the traffic loading of the bands/carriers/RATs would be balanced. At least the path loss difference between different bands should be compensated to avoid UEs concentrating to a certain frequency layer.

Traffic load balancing: This is to balance the loading of active state UEs, using redirection for example. In E-UTRAN, traffic load balancing is essential because of the shared channel nature. That is, the user throughput decreases as the number of active UEs in the cell increases, and the loading directly impacts on the user perception.

UE capability: As E-UTRAN bands/carriers may be extended in the future, UEs having different band capabilities may coexist within a network. It is also likely that roaming UEs have different band capabilities. Overlaying different RATs adds to this variety.

Hierarchical cell structures: As in UTRAN, hierarchical cell structures (HCS) may be utilised in E-UTRAN to cover for example, indoors and hot spots efficiently. It is possible that E-UTRAN is initially deployed only at hot spots, in which case this driver becomes essential for inter-RAT, not just for inter-frequency. Another use case would be to deploy a large umbrella cell to cover a vast area without having to deploy a number of regular cells, while providing capacity by the regular cells on another frequency.

Network sharing: At the edge of a shared portion of a network, it will be necessary to direct UEs belonging to different PLMNs to different target cells.

Private networks/home cells: Cells that are part of a sub-network should prioritise the camping on that sub-network. UEs that do not belong to private sub-networks should not attempt to camp or access them.

Subscription based mobility control: This mobility driver aims to limit the inter-RAT mobility for certain UEs, e.g., based on subscription or other operator policies.

Service based mobility control: An operator may have different policies in allocating frequencies to certain services. For example, the operator may concentrate VoIP UEs to a certain frequency layer or RAT (e.g., UTRAN or GERAN), if evaluations prove this effective. UEs requiring higher data rates may better be served on a frequency layer or RAT (e.g., E-UTRAN) having a larger bandwidth. The operator may also want to accommodate premium services on a certain frequency layer or RAT, that has better coverage or larger bandwidth.

MBMS: For Release-9, no new mobility procedures compared to Release-8 are included specifically for MBMS. In future releases the following should be considered. As MBMS services may be provided only in certain frequency layers, it may be beneficial/necessary to control inter-frequency/RAT mobility depending on whether the UE receives a particular MBMS service or not. For MBMS scenarios only, UE based service dependent cell reselection might be considered acceptable. This aspect also depends on the UE capability for simultaneous reception of MBMS and unicast.


While the issues mentioned above drive E-UTRAN towards “aggressive” mobility control, the limiting factors also have to be considered:

UE battery saving: The mobility solution should not consume excessive UE battery, e.g., due to measurements, measurement reporting, broadcast signalling reception, or TA update signalling.
Network signalling/processing load: The mobility solution should not cause excessive network signalling/processing load. This includes over-the-air signalling, S1/X2 signalling, and processing load at network nodes. Unnecessary handovers and cell reselections should be avoided, and PCH and broadcast signalling, as well as dedicated signallings, should be limited.

U-plane interruption and data loss: U-plane interruption and data loss caused by the mobility solution should be limited.

OAM complexity: The mobility solution should not demand excessive efforts in operating/maintaining a network. For example, when a new eNB is added or an existing eNB fails, the mobility solution should not incur excessive efforts to set up or modify the parameters.

More details available in Annex E of 3GPP TS 36.300

Home Relays for LTE-Advanced

If you look at the Home eNodeB (Femtocell) architecture, the HeNB is connected to its gateway which in turn is connected to MME/S-GW. There is a considerable amount of technology investment in this approach. The HeNB consists of complete protocol stack, the HeNB-GW is an expensive piece of equipment and there is lots of other things including the management software, etc.

Now in LTE-A, there is a concept of Relays which we have talked about. The Relays do not contain the complete stack (generally just L1 and L2). If capacity is not an issue but coverage, then we may be able to use Home Relays.

The backhaul for Femtocell is Internet whereas for Relay its generally the same Radio resources within the cell. I guess the main thing for Relay is the requirement of reasonably good channel (Line of sight maybe). Home Relays can use the Internet connection but rather than connection terminating in some kind of gateway, it can terminate at the actual eNB.

There are already many advanced antenna techniques that can handle the transmission and reception without much interference and maybe the SON algorithms may need some additional improvements.

The main thing is that if this technology becomes reality then it may cost less than $50 per Home relay and would become really a commonplace.

Femtocells for Beginners

Good beginner level primer for Femtocells is available at Radio-Electronics website. It covers important topics like architecture, interference, security and health issues. Wort a read if you are a newbie to the Femto domain. Click here.

Speech for Mobile to become big industry

Its interesting that its not only Google that experimenting with Voice Recognition and Voice search but a whole lot of other players. Earlier I blogged about Real time Speech Translation and another one was the Voicemail search. Google's search App also allows to search using voice rather than by entering text.

SpeechTek Europe 2010 is a new conference that promises to make everyone aware of the new Speech Technologies and their application in Mobile and other domains.

From EarthTimes:

Produced by the publishers of the industry’s best-read magazine, Speech Technology, SpeechTEK Europe is the sister of the highly successful New York annual event series and aims to capitalise on the wealth of speech innovators based here in Europe.

The conference has been developed by a Steering Committee which comprises some of the industry’s most respected thought leaders. Here they share their insights into the future for speech technologies, how they are developing, and where they will be used.

Loquendo’s Vice President of International Sales, Rosanna Duce, predicts that voice control will be a major growth area in the next five years:

“One important emerging speech technology is undoubtedly the voice control of all kinds of devices, for example, PDAs, mobile phones, DVD players.” She comments, “These technologies are currently being expanded and upgraded to allow all functions to be accessed using voice, thus eliminating the need to use a keyboard. Consumer demand seems to suggest that the option to dictate text messages will be a major source of growth in this area, as will be the reading of incoming messages by a TTS application bundled with the phone/PDA.”

Nava Shaked, CEO of Business Technologies, agrees,

“The combination of voice search engines, internet and mobile is a real opportunity for speech technology growth and influence. This includes the introduction of previously unseen applications for voice user interface and transcription. The combination of voice and video is also promising and will be inevitable in our interaction with multimedia.”

James Larson, the Conference Chair, supports these views,

“Multimodal applications on mobile devices will enable customers to not only speak and listen, but to also read and type and use additional modes in interaction. These apps will be easy to learn, easy to use, and much more natural than current voice-only apps or GUI-only apps. They will always be available, and customers can use them wherever they are, not just at their desktop or in their car.” He concludes, “Multimodal applications on mobile devices will dramatically change how we interact with appliances - TV, radio, environmental control - with the internet, and with other people.”

The SpeechTEK Europe conference programme explores these trends and the implications for the industry as a whole. Real world applications and case studies are a particular feature of the event, so delegates can see for themselves how speech is working in a variety of different environments, how to select and implement the technology, and how to evaluate its performance.

The full SpeechTEK Europe programme is available at: www.speechtek.com/europe2010 along with registration information, details of registration savings, and free entry exhibition tickets.

IPv6 transition in cellular networks gaining momentum

IPv6 is good and we all know that. I has been talked for years but practically it hasnt found much success. Verizon made some noise last year but I am not sure of the conclusion.

Just to recap, IPv4 was introduced back in 1982 and IPv6 work started since 1995. IPV4 uses 32 bit (4 bytes) addresses while IPV6 uses 128 bit (16 bytes) addresses. Theoretically we would now have 2^96 times more addresses than in case of IPv4.

Most of network infrastructure manufacturers have their equipment ready for IPv6 as some of the handset manufacturers. The main driver being that someday soon IPv4 addresses would be exhausted (Internet Assigned Numbers Authority will run out of IPv4 addresses in September of 2011, based on current projections) and their equipment would be ready to provide IPv6 addresses without any problems.

Recently, IETF-3GPP Workshop on IPv6 in cellular networks was held in San Francisco, USA on 1 - 2 March, 2010. There are lots of interesting presentations available here for people who want to dig a bit deeper. The concluding report that summarises the presentations and discussions are available here. Here is a brief summary from one of the reports (with links at the end):

Summary

• Scenarios for IPv6 migration were discussed based on 3GPP Technical Report 23.975
• The discussion focused on validating the scenarios
• General IPv6 transition and deployment guidelines were outlined based on input from IETF
• Solutions for migration and v4-v6 co-existence were presented
  
• Solutions included existing RFCs and working group items but also proposals in Internet Drafts
• Gap analysis wrt transition scenarios was discussed

Conclusions on scenarios

• Scenarios 1 and 3 based on dual-stack and IPv6-only deployments were generally recognized as valid
• See docs IPW100013, IPW100028
• Scenario 2 was also recognized as valid, addressing two separate problems related to insufficient RFC1918 space and subscriber identification
• See doc IPW100027
• Scenario 4 did not receive wide support from the workshop, largely because it was felt that it addressed a problem already solved by other scenarios
• Variants of some of these scenarios were brought up during the discussions, conclusions were not reached on these
• These may need further discussion

Conclusions on solutions

• It was recognized that necessary support in the network and devices is already available to “switch on” IPv6 in 3GPP networks
• Some networks reported running dual stack
• Some networks reported running IPv6-only now
• Solutions enhancing existing mechanisms for dual stack deployments and new solutions for IPv6-only deployments drew wide support
• Gateway-initiated Dual Stack Lite
• Stateful IPv4/IPv6 translation

Next steps: 3GPP

• IETF and 3GPP are expected to focus further work based on the conclusions of the workshop
• Note that the workshop itself does not have the mandate to make formal decisions
• 3GPP is expected to identify possible normative specification impacts, if any, of the preferred solutions
• A need was identified to provide more operational guidelines about IPv6 deployment to 3GPP operators
• The best location for these guidelines is FFS (e.g. 3GPP TR 23.975, GSMA, etc)

Next steps: IETF

• IETF and 3GPP are expected to focus further work based on the conclusions of the workshop
• Note that the workshop itself does not have the mandate to make formal decisions
• IETF is encouraged to continue working on stateless and stateful IPv4/IPv6 translation mechanisms
• These mechanisms are being worked on in IETF BEHAVE group
• IETF is also encouraged to consider new solutions that are not yet working group items
• Gateway Initiated DS Lite
• Per-interface NAT44 bindings addressing IPv4 address shortage
• Note that the workshop has not set any timelines

Further reading:

• 3GPP TR 23.975: IPv6 Migration Guidelines, Release 10 (http://www.3gpp.org/ftp/Specs/archive/23_series/23.975/)
• 'IETF-3GPP Workshop on IPv6 in cellular networks' Workshop Presentations (http://www.3gpp.org/ftp/workshop/2010-03-01_IPv4-to-IPv6_with-IETF/Docs/)
• 'IETF-3GPP Workshop on IPv6 in cellular networks' Workshop Summary Report(http://www.3gpp.org/ftp/workshop/2010-03-01_IPv4-to-IPv6_with-IETF/Report/)
• 3G Americas Report on 'Transitioning to IPv6' (http://3gamericas.org/documents/2008_IPv6_transition_3GA_Mar2008.pdf)
• Is IPv6 Finally on the Verge? - Light Reading (http://www.lightreading.com/document.asp?doc_id=189143)
• Jari Arkko's Publications (http://www.arkko.com/publications.html)

The size of Mobile Market (Amazing Pic)

Click on the photograph to view the larger version. I assume, its self explanatory.

Via: Mr. Mobile Blog