Temporary Identities in LTE/SAE - 1

An MS may be allocated three TMSIs, one for services provided through the MSC (TMSI), one for services provided through the SGSN (P-TMSI for short) and one for the services provided via the MME (M-TMSI part GUTI for short).

The purpose of the GUTI is to provide an unambiguous identification of the UE that does not reveal the UE or the user's permanent identity in the Evolved Packet System (EPS). It also allows the identification of the MME and network. It can be used by the network and the UE to establish the UE's identity during signalling between them in the EPS.

The GUTI has two main components:

• one that uniquely identifies the MME which allocated the GUTI; and
• one that uniquely identifies the UE within the MME that allocated the GUTI.

Within the MME, the mobile shall be identified by the M-TMSI.

The Globally Unique MME Identifier (GUMMEI) shall be constructed from the MCC, MNC and MME Identifier (MMEI).

The MMEI shall be constructed from an MME Group ID (MMEGI) and an MME Code (MMEC).

The GUTI shall be constructed from the GUMMEI and the M-TMSI.

For paging purposes, the mobile is paged with the S-TMSI. The S-TMSI shall be constructed from the MMEC and the M-TMSI.
S-TMSI = MMEC + M-TMSI

The operator shall need to ensure that the MMEC is unique within the MME pool area and, if overlapping pool areas are in use, unique within the area of overlapping MME pools.

The GUTI shall be used to support subscriber identity confidentiality, and, in the shortened S-TMSI form, to enable more efficient radio signalling procedures (e.g. paging and Service Request).


The format and size of the GUTI is therefore the following:
GUTI = GUMMEI + M-TMSI, where
GUMMEI = MCC + MNC + MME Identifier and
MME Identifier = MME Group ID + MME Code
MCC and MNC shall have the same field size as in earlier 3GPP systems.
M-TMSI shall be of 32 bits length.
MME Group ID shall be of 16 bits length.
MME Code shall be of 8 bits length.

During Handover to GERAN/UTRAN
RAI = MCC + MNC + LAC + RAC
E UTRAN "MCC" maps to GERAN/UTRAN "MCC"
E UTRAN "MNC" maps to GERAN/UTRAN "MNC"
E UTRAN "MME Group ID" maps to GERAN/UTRAN "LAC"
E UTRAN "MME Code" maps to GERAN/UTRAN "RAC" and is also copied into the 8 most significant bits of the NRI field within the P TMSI;

"P-TMSI" includes the mapped NRI
P TMSI shall be of 32 bits length where the two topmost bits are reserved and always set to 11.

E UTRAN "M-TMSI" maps as follows:
6 bits of the E UTRAN "M-TMSI" starting at bit 29 and down to bit 24 are mapped into bit 29 and down to bit 24 of the GERAN/UTRAN "P TMSI";
16 bits of the E UTRAN "M-TMSI" starting at bit 15 and down to bit 0 are mapped into bit 15 and down to bit 0 of the GERAN/UTRAN "P TMSI";
and the remaining 8 bits of the E UTRAN "M-TMSI" are mapped into the 8 MBS bits of the "P-TMSI signature" field.

Abbreviations Summary:
GUTI - Globally Unique Temporary UE Identity
GUMMEI - Globally Unique MME Identifier
MMEGI - MME Group ID
MMEC - MME Code
S-TMSI = SAE Temporary Mobile Subscriber Identity
M-TMSI = MME Temporary Mobile Subscriber Identity

Reference: 3GPP TS 23.003: Technical Specification Group Core Network and Terminals; Numbering, addressing and identification (Release 8) - Section 2.8

LTE device specs now made available by Verizon

Verizon is moving aggressively towards its plans for LTE and in this process the company released its initial set of technical specs for devices that will run on its Long Term Evolution (LTE) network, which Verizon will launch next year on a commercial basis.

The new specifications are designed to offer guidelines for both access and data transport for LTE devices and will serve as a roadmap for developers who choose to develop devices for submission to the LTE certification process.

The specifications can be downloaded from this link.

When you go on the link above you can see an invitation from that Verizon to join their LTE specification web Conference on May 13th for additional details and an opportunity to ask questions. The primary objective of this conference is to encourage developers to design devices that can take advantage of 4G network speeds and capabilities.

My Doggie Ring Ring

An employee of Japanese mobile phone carrier KDDI poses as she displays the company's new polka dot pattern mobile phone and dog-shaped phone holder designed by Japanese artist Yayoi Kusama in Tokyo.

The product named My Doggie Ring-Ring is priced at 1 million yen ($10,008) and will go on sale in Japan this summer for a limited edition of 100 sets.

Sci-Fi tech that we are still waiting for

Back in 1986, I used to subscribe to a magazine called '2001' which discussed about technologies of the future. One of the things I remember reading is that by 2001 we would have cars that would run on water and prototype of cars that would be able to fly. We are just starting to see cars that would work on hydrogen and emit water vapour. But its far from car that would work on water. We are still I would say long way away from prototype of flying cars.

IT PRO has an article on top 10 technologies we have been wishing for but not too close to reality yet. Have a look here.

Rough time for telcomm vendors but sees light ahead

There have been many reports over the past year about the recession and hence the effects on the telecomm companies.

The verdict was already out that the telecom equipment vendors are bracing for what is expected to be a fairly rough round of first-quarter earnings, with the global economic recession cutting into demand from both consumers and carriers alike, according to a report in the Wall Street Journal

The report also forecasted that some of the world's biggest European equipment vendors, found that while some would fare better than others, 2009 will generally be more difficult than 2008 for the companies.

Amid all these developments came the report yesterday when Nokia reported a worse-than-expected 90 per cent slump in first quarter profits.

This is Finnish mobile group's worst results since 2001 and rightly so, blamed on to the global economic downturn which has hit phone sales.

Mobile phone companies have been hit hard by a sharp drop in consumer spending. Nokia said it sold 93.2 million handsets during the first quarter, down 19 per cent from a year earlier and down 18 per cent from the fourth quarter.

Sony Ericsson, which has its headquarters in London, has also announced today that it’ll be slashing another 2,000 jobs around the world. The latest cost-cutting drive comes as the company posted a €293m (£258m) net loss for the first three months of the year.

However Nokia still maintained its market share which remained steady at 37 percent. The company also calmed jittery investors by reaffirming its prediction that the mobile market would shrink by 10 per cent this year, and the decline would level out in the second half of the year. It retained its operating margin forecast for its devices and services business.

Although the above news looks to be shocking but it didn’t stop the company’s shares to rise 9.5 per cent to €11.05 on the Helsinki stock exchange. The primary reason for the rise is that the investors were cheered by the company holding steady on its outlook after a grim quarter.
Similar to Nokia, Sony Ericsson too has vowed to return to profitability as quickly as possible thus calming the investors.

Like many other analysts especially in the financial world, telecom vendors like Nokia and Sony Ericsson too believe that there are nascent signs of relative stability going into the second quarter.

I still believe it’s a little bit too early to call a bottom on demand in the mobile devices business.

However most of the analysts expect that companies to return to profitability in the second half of 2010 thus showing a light at the end of the tunnel.

Black-listed and White-listed cells in E-UTRAN

One interesting thing done in LTE is that when System Information is transmitted, there is a list of cells known as ‘blacklisted’ cells. These black-listed cells can be Intra-frequency, Inter-frequency or Inter-RAT cells. These are the cells that UE should not consider while doing measurements, handovers or cell-reselections. The other list that the UE should consider is referred to as the white-list.

The black-listing is provided in the SystemInformationBlockType4 and SystemInformationBlockType5 that is transmitted by RRC in E-UTRAN.

By providing a black-list of the cells, the UE can avoid wasting time performing measurements on that frequency and then reading the System Information only to find out that there was no point of doing this operation. At the same time the neighbour list can be reduced and the amount of cells the UE reports in measurements can be reduced. The UE can also re-select to a new cell faster because the neighbour cell list size is reduced.

The possible reasons for black listing could be that a cell is reserved for operator then the UE's should not be able to use them. Similarly if the cell is reserved for future use or reserved for private use (Femtocells?) or in a scenario where it wont be possible for the UE to reselect it (Examples are cells that are separated by a river and micro cells that are in two different skyscrapers, etc).

I havent gone through the specifications in detail yet but it may be possible to use this information in case of Femtocells. The neighbouring Femto's can be included as black-listed cells so that the UE dont try to camp on them.

M is for Manga - Comics on the Mobile

The Independent newspaper has an interesting photo gallery on the Japanese Comics, better known as Manga. Check it out here.