LTE CS Fallback Procedure

From a 3GPP presentation by Hannu Hietalahti:

1. CS FallBack from EPS to CS domain

2. CSFB reuses voice and other CS-domain services provided by legacy CS infrastructure

3. EPS redirects the UE to CS Domain for CS services

3a. SMS can be delivered to the UE without redirecting to CS Domain

3b. After CS service the UE returns to LTE, depending on coverage and policy

4. User can decide, based on CLI, whether to accept CSFB request

5. Application of CSFB:

5a. CS capable device camping on LTE cell can establish/receive CS services

5b. Reuse of existing CS infrastructure for voice service until IMS VoIP is deployed

5c. Provide voice roaming support with LTE

5d. Support E911 using existing CS infrastructure

5e. Rel-9 IMS provides full emergency call support

5f. Requires overlapping CS domain coverage

Note: CSFB applies between LTE and GSM, WCDMA and 1xRTT

LTE CS and PS voice service capabilities and architecture

From a 3GPP presentation by Hannu Hietalahti:

Emergency Calls in LTE/SAE Release-9

From a 3GPP presentation by Hannu Hietalahti:

Emergency calls in LTE

Regulatory requirement of emergency calls is supported in Rel-9 for LTE:

1. Detection of emergency numbers in UE

2. Indication and prioritisation of emergency calls

3. Location services, both for routing and user location data for PSAP (Public Safety Answering Point)

4. Callback is possible, but processed as normal call without exceptions

UE matches digits dialledby the user with list of known emergency numbers

1. Emergency number list in the UE is common for CS and PS domain use

2. Default 112 and 911, USIM pre-configuration, downloaded in MM procedure

3. In case of match, the UE shall initiate the call as an emergency call

In IMS emergency calls the UE translates dialled number into emergency service URN

1. Service URN with a top-level service type of "sos" as specified in RFC5031

2. Additionally, sub-service type can be added to indicate emergency category if information on the type of emergency service is known (fire, ambulance, police,…)

P-CSCF (Proxy - Call Session Control Function) must also be prepared to detect emergency call if the UE is not aware of local emergency call

1. This is backup for those cases when the (roaming) UE does not have full information of all local emergency call numbers and initiates a normal call

2. From EPC perspective, it will be a normal PDN connection

Benefit of location information

1. P-CSCF discovers the regionally correct PSAP to take the emergency call

2. PSAP gets information on the precise user location

Related Posts:

• 3GPP Release-9 Features updated
• Service Specific Access Control (SSAC) in 3GPP Release 9
• Public Warning System (PWS) in Release-9
• Europe makes 'eCall' high priority
• 3GPP Earthquake and Tsunami Warning service (ETWS)

'Wi-Fi Direct': New Standard and competition to Femtocells and Bluetooth

Last month when I blogged about WiFi as 4G, i got mixed reactions. Some suggesting that WiFi is just a filler till Femtocells become prevalent and others suggested that in future all devices would with 3G/HSPA/LTE/4G enabled so there may be no need for WiFi.

Well, yesterday I read about the new Wi-Fi Direct (formerly known as 'Wi-Fi Peer-to-Peer') standard that is supposed to make WiFi devices easier to operate with other WiFi devices. I havent explored the security options but I am sure they are well thought out.

Before we go further, you may want to check out the WiFi Direct official video below:

There is an interesting piece in PC World that compares Bluetooth 4.0 with Wi-Fi Direct. I am sure soon both these camps would be listing the merit of their standards and dissing the other one. According to the Register, Bluetooth never really took off in the US. They think Wi-Fi has bigger clout and this would translate to WiFi Direct success.

WiFi Alliance has a recently revised FAQ on Wi-Fi Direct here. Very interesting read. A Media presentation is embedded below and can be downloaded from Slideshare here.

'Wi-Fi Direct' Media Presentation

View more presentations from Zahid Ghadialy.

The devices have already started undergoing certification and commercial devices should be available by the end of this year.

Finally, while there is a lot of debate going on about WiFi v/s Femtocells and I respect everyone's views and arguments on this debate, I think Wi-Fi direct may give a kicking to the Femtocell manufacturers where it hurts the most.

One of the strong arguments in the favour of Femtocell is the seamless roaming. With Wi-Fi direct you may be able to seamlessly connect to various Wi-Fi devices and Access points. This certainly counts big time in their favour.

Certainly the gate is still wide open for some Femtocell based killer apps which would turn the tide in their favour but for now I am looking forward to some Wi-Fi direct devices.

Understanding smartphone traffic - Interesting Presentation

Understanding smartphone traffic - Droidcon

View more presentations from Ericsson Labs

If you like the above then also check out the Fast Dormancy in Release-8.

ETSI M2M Workshop summary and conclusions

As I mentioned earlier about the M2M workshop held in Paris, the following are the highlights from press release after the event:

ETSI's first Open Machine-to-Machine Workshop broke all records for attendance, laying out the next steps for achieving M2M applications worldwide, and confirming a leading role for the standards organisation.

'Machine-to-Machine (M2M) communications need standards – and ETSI is taking the lead to make sure that the standards are in place.' This was the main conclusion from ETSI's M2M workshop which took place on 19 and 20 October. With over 220 attendees from across the world, this was the most popular ETSI workshop to date, with the high degree of interest reflecting the enormous potential that is foreseen for M2M applications and technologies.

Participants heard how existing and evolving communication technologies networks (mostly wireless (cellular and low-power), but also fixed networks, including power line communications) provide a firm basis for connecting M2M sensors and applications. Specification of appropriate interfaces that allow network technology neutrality is a priority, and one that ETSI is already addressing.

The workshop included two live demonstrations organised by InterDigital Inc. These demonstrated an M2M gateway and core network, and an M2M Wireless Personal Area Network (sensors connecting via low-power wireless devices to a database, simulating e-Health, home automation and security application scenarios). The implementations were based on current specifications from ETSI's M2M Technical Committee and confirmed both the effectiveness of the implications and of the ETSI specifications. In addition, poster sessions presented the work of six research and development projects related to M2M and the Future Internet, part of the European Commission's 7th Framework Programme (FP7).

The standards work of ETSI's M2M Technical Committee is reaching an advanced stage, and many network operators are encouraging a first release of M2M standards by early 2011. The committee is currently finalising the architecture for the service platform that will enable the integration of multiple vertical M2M applications. The workshop confirmed that ETSI is well placed to address a vital aspect of standardisation in support of M2M – the specification of interfaces that will facilitate the interconnection and interoperability of the diverse applications and of the networks that will underlie them.

Marylin Arndt of France Telecom, Chairman of ETSI's M2M Technical Committee, said: 'The committee will continue in its role of creating standards that build on what we already have, to ensure that the emerging 'vertical' M2M applications can be supported effectively. At the same time, the committee (and ETSI in general) has a vital responsibility to co-ordinate and direct the wider work on M2M. We are here to lead the way.'

All presentations could be downloaded from here.

The conclusions from the meeting is summarised in the presentation embedded below:

ETSI M2M Workshop Oct. 2010 Conclusions

View more presentations from Zahid Ghadialy

Complete Coverage of 4G World 2010 ... in case you missed

Wireless Week has a very good magazine with detailed highlights of everything that happened in the recently concluded 4G World event in Chicago. The links are as follows:

Day 1

Day 2

Day 3

NGMN Top 10 Operational Efficiency Recommendations

Setting up and running networks is a complex task that requires many activities, including planning, configuration, Optimization, dimensioning, tuning, testing, recovery from failures, failure mitigation, healing and maintenance. These activities are critical to successful network operation and today they are extremely labour-intensive and hence, costly, prone to errors, and can result in customer dissatisfaction. This project focuses on ensuring that the operators’ recommendations are incorporated into the specification of the 3GPP O&M (and similar groups in other standardisation bodies) so that this critical task moves towards full automation.

The overall objective is to provide operators with the capability to purchase, deploy, operate and maintain a network consisting of Base Stations (BTS) and “Access Gateways (AGw)” from multiple vendors. The NGMN project Operational Efficiency OPE has taken the task to elaborate solutions and recommendations for pushing the operational efficiency in NGMN networks and has produced recommendations on standards and implementations. The NGMN OPE project also influenced strongly the setup of a TOP10 document reflecting main recommendations in operational area. This document (embedded below) binds these two sources which are anyhow strongly linked together into one common NGMN recommendation document.

NGMN Top OPE Recommendations

View more documents from Zahid Ghadialy.

IMB and TDtv (and DVB-H)

Its long time since I blogged about TDtv. Its been quite a while since I heard about TDtv. Apparently its been superseded by IMB, aka. Integrated Mobile Broadcast.

IMB is used to stream live video and store popular content on the device for later consumption. This results in a significant offloading of data intensive traffic from existing 3G unicast networks and an improved customer experience. The multimedia client features an intuitive electronic program guide, channel grid and embedded video player for live TV viewing and video recording. All IMB applications can be quickly and cost-effectively adapted to support all major mobile operating systems and different mobile device types, including smartphones, tablets and e-readers.

IMB was defined in the 3GPP release 8 standards, and was recently endorsed by the GSMA as their preferred method for the efficient delivery of broadcast services. In June 2010, O2, Orange and Vodafone – three of the five major UK mobile operators – announced that they have teamed up for a three-month trial that will explore IMB wireless technology within a tranche of 3G TDD spectrum.

This spectrum already forms part of the 3G licenses held by many European mobile operators, but has remained largely unused because of a lack of appropriate technology. Currently, 3G TDD spectrum is available to over 150 operators across 60 countries, covering more than half a billion subscribers. IMB enables spectrally efficient delivery of broadcast services in the TDD spectrum based on techniques that are aligned with existing FDD WCDMA standards. This enables a smooth handover between IMB and existing 3G networks.

Issues that previously limited uptake of IMB, or IPWireless' tdTV system, have now all been addressed. Namely, the standard now allows for smooth handover between IMB and unicast delivery; has the potential to be integrated onto a single W-CDMA chip rather than requiring a separate chip; and has resolved interference issues with FDD W-CDMA, at least for spectrum in the 1900MHz to 1910MHz range.

IP Wireless already had a trial at Orange and T-Mobile in the UK (which have just agreed to merge), but in that pilot each 5MHz segment only gave rise to 14 TV channels per operator. The new standard could support 40 separate TV channels if two operators shared their TDD spectrum.

The GSMA announced its support and is backed up with additional support from both IPWireless and Ericsson as well as operators Orange, Softbank and Telstra.

There have been recently quite a few bad news for DVB-H and on top of that IP Wireless has announced that Samsung is going to be releasing phones with IMB support so it may be that we will see IMB sometime next year.

The GSMA paper that details IMB service scenarios and System requirements is embedded below:

Integrated Mobile Broadcast (IMB) Service Scenarios and System Requirements

View more documents from Zahid Ghadialy.

Fast Dormancy in Release-8

Nokia Siemens Networks has collaborated with Qualcomm to carry out the industry’s first successful interoperability test of the new 3GPP standardized Release 8 Fast Dormancy feature. Unlike proprietary approaches to fast dormancy, the new standard allows operators to take full advantage of smart network features such as Cell_PCH without worrying that individual handset settings will ignore network controls.

The test was conducted at Nokia Siemens Networks’ Smart Lab in Dallas using Nokia Siemens Networks’ Flexi Multiradio Base Station and Radio Network Controller and Qualcomm’s QSC7230TM smartphone optimized chipset. The test showed how smartphones can act dynamically, exploiting Cell_PCH on Nokia Siemens Networks’ smart networks or adjusting to Fast Dormancy on other vendors’ traditional networks.

In fact the operators have been getting upset quite for some time because of smartphone hacks that save the UE battery life but cause network signalling congestion. See here.

To explain the problem, lets look at the actual signalling that occurs when the UE is not transmitting anything. Most probably it gets put into CELL_PCH or URA_PCH state. Then when keep alive messages need to be sent then the state is transitioned to CELL_FACH and once done its sent back to CELL_PCH. Now the transitioning back from CELL_FACH (or CELL_DCH) to CELL_PCH can take quite some time, depending on the operator parameters and this wastes the UE battery life.

To get round this problem, the UE manufacturers put a hack in the phone and what they do is that if there no data to transmit for a small amount of time, the UE sends RRC Signalling Connection Release Indication (SCRI) message. This message is supposed to be used in case when something is gone wrong in the UE and the UE wants the network to tear the connection down by sending RRC Connection Release message. Anyway, the network is forced to Release the connection.

If there is another requirement to send another keep alive message (they are needed for lots of apps like Skype, IM's, etc.) the RRC connection would have to be established all over again and this can cause lots of unnecessary signalling for the network causing congestion at peak times.

To speed up the transitioning to CELL_PCH state in Release-8 when the UE sends SCRI message, its supposed to include the cause value as "UE Requested PS Data session end". Once the network receives this cause it should immediately move the UE to CELL_PCH state.

This is a win win situation for both the network and the UE vendors as long as a lot of UE's implement this. The good thing is that even a pre-Rel8 UE can implement this and if the network supports this feature it would work.

GSMA has created a best practices document for this feature which is embedded below.

Fast dormancy from Dono Miguel

Further Reading:

• UMTS State Switching and Fast Dormancy Evolution - Martin Sauter
• RP-090941 - System impact of poor proprietary Fast Dormancy implementations
• RP-090942 - Clarification on Enhanced SCRI approach for fast dormancy
• RP-090960 - Configuration of Fast Dormancy
• R2-096882 - Changes to Release-8 Fast Dormanc