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Understand WLAN Offload

Monday, 28 February 2011

More than 50 Billion Connected Devices

I blogged about the 50 Billion connected devices as predicted by Ericsson last year. With the promised 'Internet of things' and 'connected world' we may see 50 billion devices not too far in the near future. Here is a recent whitepaper from Ericsson on this topic.
More than 50 billion connected devices
View more documents from Zahid Ghadialy
You may also be interested in this old presentation from Ericsson on the same topic available here.

Friday, 25 February 2011

Attach Sequence for LTE Radio

I have in past posted a complete Attach Sequence on the 3G4G website for LTE Radio Signaling but included the signalling on a few nodes. Recently I came across a signalling example in NTT Docomo technical journal which was less detailed but at a higher level and detailed signalling on these other nodes. It may be worthwhile brushing up the LTE Architecture diagram before diving into this.

With EPC, when a terminal connects to the LTE radio access system it is automatically connected to the PDN and this connected state is maintained continuously. In other words, as the terminal is registered on the network (attached) through the LTE radio access system, a communications path to the PDN (IP connectivity) is established.

The PDN to which a connection is established can be preconfigured on a per-subscriber basis, or the terminal can specify it during the attach procedure. This PDN is called the default PDN. With the always-on connection function, the radio link of the connection only is released after a set amount of time has elapsed without the terminal performing any communication, and the IP connectivity between the terminal and the network is maintained. By doing this, only the radio link needs to be reconfigured when the terminal begins actual communication, allowing the connection-delay time to be reduced. Also, the IP address obtained when the terminal attaches can be used until it detaches, so it is always possible to receive packets using that IP address.

The information flow for the terminal attaching to the network up until the connection to the PDN is established is shown in Figure 2 below.

Steps (1) to (3): When the terminal establishes a radio control link for sending and receiving control signals with the eNodeB, it sends an attach request to the MME. The terminal and MME perform the required security procedures, including authentication, encryption and integrity.

Steps (4) to (5): The MME sends an update location request message to the Home Subscriber Server (HSS), and the HSS records that the terminal is connected under the MME.

Step (6): To begin establishing a transmission path to the default PDN, the MME sends a create session request to the S-GW.

Steps (7) to (8): When the S-GW receives the create session request from the MME, it requests proxy binding update to the P-GW. The P-GW allocates an IP address to the terminal and notifies the S-GW of this information in a proxy binding acknowledgement message. This process establishes a continuous core-network communications path between the P-GW and the S-GW for the allocated IP address.

Step (9): The S-GW prepares a radio access bearer from itself to the eNodeB, and sends a create session response signal to the MME. The create session response signal contains information required to configure the radio access bearer from the eNodeB to the S-GW, including information elements issued by the S-GW and the IP address allocated to the terminal.

Steps (10) to (11) and (13): The MME sends the information in the create session response signal to the eNodeB in an initial context setup request signal. Note that this signaling also contains other notifications such as the attach accept, which is the response to the attach request. When the terminal receives the attach accept in Step (11), it sends an attach complete response to the MME, notifying that processing has completed.

Step (12): The eNodeB establishes the radio data link and sends the attach accept to the terminal. It also configures the radio access bearer from the eNodeB to the S-GW and sends an initial context setup response to the MME. The initial context setup response contains information elements issued by the eNodeB required to establish the radio access bearer from the S-GW to the eNodeB.

Steps (14) to (15): The MME sends the information in the initial context setup response to the S-GW in a modify bearer request signal. The S-GW completes configuration of the previously prepared radio bearer from the S-GW to the eNodeB and sends a modify bearer response to the MME.

Through these steps, a communications path from the terminal to the P-GW is established, enabling communication with the default PDN.

If the terminal performs no communication for a set period of time, the always-on connection function described above releases the radio control link, the LTE radio data link, and the LTE radio access bearer, while maintaining the core network communications path.

After the terminal has established a connection to the default PDN, it is possible to initiate another connection to a different PDN. In this way it is possible to manage PDNs according to service.

For example the IMS PDN, which provides voice services by packet network, could be used as the default PDN, and a different PDN could be used for internet access.

To establish a connection to a PDN other than the default PDN, the procedure is the same as the attach procedure shown in Fig.2, excluding Steps (4) and (5).

TERMS:

Attach: Procedure to register a terminal on the network when, for example, its power is switched on.

Detach: Procedure to remove registration of a terminal from the network when, for example, its power is switched off.

Integrity: Whether the transmitted data is complete and has not been falsified. Here we refer to pre-processing required to ensure integrity of the data.

Bearer: A logical transmission path established, as between the S-GW and eNodeB.

Context setup: Configuration of information required for the communications path and communications management.

Wednesday, 23 February 2011

Circuit Switched Fallback (CSFB): A Quick Primer

I have explained CSFB with basic signalling here and there is a very interesting Ericsson whitepaper explaining all Voice issues in LTE here.

The following CSFB details have been taken from NTT Docomo Technical Journal:

The basic concept of CS Fallback is shown in Figure 1. Given a mobile terminal camping on LTE, a mobile terminating voice call arrives at the terminal from the existing CS domain via EPC. On receiving a paging message, the mobile terminal recognises that the network is calling the mobile terminal for CS-based voice and therefore switches to 3G. The response confirming the acceptance of a call request is then sent from the mobile terminal to the 3G-CS system, and from that point on, all call control for the voice service is performed on the 3G side.

The CS Fallback consists of a function to notify a mobile terminal of a call request from the CS domain and combined mobility management functions between CS domain and EPC for that
purpose. The network architecture of CS Fallback is shown in Figure 2.


One of the remarkable characteristics of the EPC supporting CS Fallback is that it connects the Mobile Switching Center (MSC) and Visited Location Register (VLR) in the 3G CS domain
with the Mobility Management Entity (MME), which provides EPC mobility management functionality. The interface connecting MSC/VLR and MME is called an SGs reference point. This
interface is based on the concept of the Gs reference point that exchanges signalling with MSC, which connects to the Serving General Packet Radio Service Support Node (SGSN), a 3G
packet switch. The SGs provides nearly all the functions provided by the existing Gs.

The CS Fallback function uses this SGs reference point to transfer the mobile terminating call requests from the CS domain to LTE. It also provides combined mobility management
between the 3G CS domain and the EPC to enable this transfer to take place.


Combined Mobility Management between CS Domain and EPC Network:

A mobile communications network must always know where a mobile terminal is located to deliver mobile terminating service requests to the mobile user on the mobile terminating side. The procedure for determining terminal location is called “mobility management". As a basic function of mobile communications, 3G and LTE each provide a mobility management function.

To complete a call using the CS Fallback function, the CS domain needs to know which LTE location registration area the mobile terminal is currently camping on. To this end, the MME must correlate mobility management control of the CS domain with that of EPC and inform MSC/VLR that the mobile terminal is present in an LTE location registration area.

The 3G core network already incorporates a function for linking mobility management of the CS domain with that of the Packet Switched (PS) domain providing packet-switching functions. As described above, the CS domain and PS domain functions are provided via separate switches. Thus, if combined mobility management can be used, the mobility management procedure for the terminal only needs to be performed once, which has the effect of reducing signal traffic in the network. This concept of combined mobility management is appropriated by the CS Fallback function. Specifically, MSC/VLR uses the same logic for receiving a location registration request from SGSN as that for receiving a location registration request from MME. This achieves a more efficient combined mobility management between the CS domain and EPC while reducing the development impact on MSC.

As described above, a mobile terminal using LTE cannot use 3G at the same time. This implies that the MME, which contains the LTE location registration area (Tracking Area (TA)), is unable to identify which MSC/VLR it should send the mobility management messages to from the TA alone. To solve this problem, the mapping of TAs and 3G Location Areas (LA) within MME has been adopted. The concept behind TA/LA mapping is shown in Figure 3. Here, MME stores a database that manages the correspondence between physically overlapping TAs and LAs. This information is used to determine which MSC/VLR to target for location registration.

The combined TA/LA update procedure for CS fallback is shown in detail in Figure 4. First, the mobile terminal sends to the MME a Tracking Area Update (TAU) request message indicating a combined TAU and the current TA in which the mobile terminal is currently present (Fig. 4 (1)). The MME then performs a location update procedure towards Home Subscriber Server (HSS), which is a database used for managing subscriber profiles (Fig. 4 (2)). Next, the MME uses the TA/LA correspondence database to identify the corresponding LA and the MSC/VLR that is managing that area, and uses the SGs reference point to send a Location Area Update (LAU) request message to the MSC/VLR together with the LA so identified (Fig. 4 (3)). The MSC/VLR that receives the LAU request message stores the correspondence between the ID of the MME originating the request and an ID such as the International Mobile Subscriber Identity (IMSI) that identifies the subscriber (Fig. 4 (4)). This enables the MSC/VLR to know which MME the mobile terminal is currently connected to and that the mobile terminal is camping on LTE. Following this, the MSC/VLR performs a location registration procedure with the HSS (Fig. 4 (5)). Finally, the MSC/VLR informs the MME of temporary user identity (Temporary Mobile Subscriber Identity (TMSI)), which is used at the time of a mobile terminating call in the CS domain, and indicates that location registration has been completed. The MME then informs the mobile terminal of the TMSI and of the LA that the mobile terminal has been registered with thereby completing combined location registration (Fig. 4 (6) (7)).

CS Fallback Call Control Procedures - Mobile Originating Call:


To originate a voice call using the CS Fallback function, a mobile terminal in the LTE location registration area must first switch (fall back) to 3G. The mobile-originating voice call procedure is shown in Figure 5. To originate a call, the mobile terminal begins by sending a CS fallback service request message to the MME (Fig. 5 (1)). Since a packet-communications transmission path (bearer) must always exist in EPC for the purpose of providing an always-on connection, the bearer also has to be handed over to 3G. To accomplish this, the MME issues a handover command to the mobile terminal in LTE and initiates a handover procedure (Fig. 5 (2)). The mobile terminal changes its radio from LTE to 3G during this procedure (Fig. 5 (3)). On completion of handover, the mobile terminal issues an originating request for voice service to the MSC/VLR. A voice-call connection is then established using an existing calloriginating procedure on 3G and the CS Fallback procedure is completed (Fig. 5(4)).

CS Fallback Call Control Procedures - Mobile Terminating Call:

The mobile terminating voice call procedure using CS Fallback is shown in Figure 6. When the MSC/VLR receives a message indicating the occurrence of a mobile terminating call (Fig. 6 (1)), the MSC/VLR identifies the corresponding MME from the call information received (Fig. 6 (2)). Then, the MSC/VLR sends a paging message (Fig. 6 (3)) towards the MME. Next, the MME sends a paging message to the mobile terminal in LTE (Fig. 6 (4)). This paging message includes an indication that the call is a CS service, and on identifying the call as such, the mobile terminal sends a CS fallback service request signal to the MME (Fig. 6 (5)). Following this, a handover procedure to 3G as described above takes place (Fig. 6 (6), (7)). The mobile terminal that is now switched to 3G sends a paging response message to the MSC/VLR at which it is registered (Fig. 6 (8)). Finally, an existing mobile terminating call procedure on 3G is executed and the CS Fallback procedure is completed (Fig. 6 (9)).

Monday, 21 February 2011

MBMS in LTE Release-9

From NTT Docomo Technical Journal:

MBMS is a bearer service for broadcast/multicast transmission of data, to transmit the same information to all interested UEs in an area over a common bearer. Note that MBMS has been supported in UTRA since Release 6.


LTE Release 9 supports basic MBMS functionality not requiring complex control. One of the main features is support for MBMS Single Frequency Network (MBSFN) transmission. With MBSFN transmission eNBs in the MBSFN area transmit the same signal simultaneously using the same time-frequency resource. The UE receives the combined signals as a single, strong signal, improving coverage and signal quality without much additional complexity in the UE. By applying MBSFN transmission, a 3GPP study concluded that to provide 95% coverage with a packet error rate of 1%, a spectral efficiency of 3 bit/s/Hz or greater can be achieved.

The logical architecture for MBMS in LTE is shown in Figure 4. The MBMS gateway (GW) distributes data received from the Broadcast Multicast Service Center (BMSC) to the relevant eNBs by IP multicast. The Multi-Cell Multicast Coordination Entity (MCE) specifies the radio resources to be used by eNBs comprising the MBSFN and ensures that the content is synchronized. To support MBMS, logical channels, namely Multicast Traffic Channel (MTCH) and Multicast Control Channel (MCCH), and a transport channel, namely Multicast Channel (MCH), are defined (Figure 5).

Thursday, 17 February 2011

Wednesday, 16 February 2011

Five quick videos from Mobile World Congress 2011 - 2









Facebook onto a SIM using Class 2 SMS

I am sure you have already heard of Gemalto's (worlds largest SIM manufacturer and supplier) Facebook on the SIM announcement. The advantage of this approach is that 100% of the existing phones will be able to support facebook (if the operator supports the application on the SIM). This is a big step0 forward. The press release says:

Gemalto’s software development team has embedded the software application into the SIM. This ensures the Facebook application is compatible with 100% of SIM-compliant mobile phones.

The innovative solution provides mobile subscribers with simple and convenient access to core Facebook features such as friend requests, status updates, wall posts or messages. It also offers unique functions: people can sign up for this service and log in directly from the SIM application. Interactive Facebook messages pop-up on the phone’s screen so people can always share up-to-the-minute posts and events. One can also automatically search their SIM phonebook for other friends and send them requests.

Facebook for SIM is extremely easy to use and is available to everyone. No data contract or application download is needed, because the software is embedded in the SIM and it uses SMS technology. As a result, it works for prepaid as well as for pay-monthly customers. Following an initial limited free trial period, Facebook for SIM then operates on a subscription model via an unlimited pass for a given period of time.

“Facebook for SIM enables operators to leverage two of their main assets: the SMS to communicate with the web application and the SIM for application distribution to the masses,” added Philippe Vallée, Executive Vice President, Gemalto. “Over 200 million people already use Facebook on handsets and those are twice as active as non-mobile users . By providing anytime, anywhere availability to the social network, Gemalto delivers on the growing demand for mobile connectivity all over the world.”

An article on the Register had more details:

The SIM-based client isn't as pretty as its smartphone contemporaries – don't expect picture streams or sliding interfaces – but it was developed with the help of Facebook, and provides text-menu-based interaction with Facebook – including status updates, pokes and friend requests – to any GSM-compatible handset through the magic of the GSM SIM Toolkit and Class 2 SMS messages.

The SIM Toolkit is part of the GSM standard and thus supported on just about every GSM handset, from the dumbest PAYG talker to the latest iGear. It allows the SIM to present menu options to the user, collect responses, and pop up alerts when new data arrives, which is all that's necessary for a basic Facebook client.


Modern handsets also allow the SIM to make TCP/IP data connections, but Gemalto is eschewing that for Class 2 SMS to ensure compatibility with the most basic handsets, and networks.

Class 2 SMS messages are delivered direct to the SIM without the user being involved, so can update friends' status messages and deliver a poke or two. The application running on the SIM then prods the handset into alerting the user.

That user's own updates are sent over SMS too, following a status change or wall posting client pastes that into an SMS, which is sent silently on its way.

How, or if, the network operator charges for all those messages flying about isn't clear. Gemalto won't name operators yet but claims to be talking to one operator who reckons that Facebook is eating half its bandwidth, and another who's already working on SIM distribution strategies.

Not that a new SIM is necessarily required – SIMs are field upgradable, though few operators deploy them with sufficient empty space for an application like this and issuing replacement SIMs is probably easier from a marketing point of view.

You can also find some of these details here.

As I have been working on SMS for the last few weeks, I decided to dig a bit deep into what these Class 2 SMS are.

Classes identify the message's importance as well as the location where it should be stored. There are 4 message classes.

Class 0: Indicates that this message is to be displayed on the MS immediately and a message delivery report is to be sent back to the SC. The message does not have to be saved in the MS or on the SIM card (unless selected to do so by the mobile user).

Class 1: Indicates that this message is to be stored in the MS memory or the SIM card (depending on memory availability).

Class 2: This message class is Phase 2 specific and carries SIM card data. The SIM card data must be successfully transferred prior to sending acknowledgement to the SC. An error message will be sent to the SC if this transmission is not possible.

Class 3: Indicates that this message will be forwarded from the receiving entity to an external device. The delivery acknowledgement will be sent to the SC regardless of whether or not the message was forwarded to the external device.

You can also read this for more details on SMS message contents

Monday, 14 February 2011

Non-Voice Emergency Services (NOVES)

Its been a while we talked about SMS for Emergency purposes and eCall. A new study item in 3GPP has looked at non-voice alternatives for Emergency purposes.

Picture Source: Dailymail

The following is from the recent 4G Americas report entitled: 4G Mobile Broadband Evolution: 3GPP Release-10 and Beyond:

Non-verbal communications such as text messaging and instant messaging via wireless devices has been very successful and continues to expand. Many of the consumers assume that they can utilize these types of non-verbal communications as mechanisms to communicate with emergency services whenever emergency assistance is required. Such mechanisms currently do not exist. The Emergency Services community has a desire to have multimedia emergency services supported with the same general characteristics as emergency voice calls.

Currently, service requirements for emergency calls (with or without the IP Multimedia Core Network) are limited to voice media. The Non-Voice Emergency Services (NOVES) is intended to be an end-to-end citizen to authority communications. NOVES could support the following examples of non-verbal communications to an emergency services network:
1. Text messages from citizen to emergency services
2. Session-based and session-less instant messaging type sessions with emergency services
3. Multimedia (e.g., pictures, video clips) transfer to emergency services either during or after other communications with emergency services.
4. Real-time video session with emergency services

In addition, to support the general public, this capability would facilitate emergency communications to emergency services by individuals with special needs (e.g., hearing impaired citizens).

The objectives of this study include the following questions for NOVES with media other than or in addition to voice:
1. What are the requirements for NOVES?
2. What are the security, reliability, and priority handling requirements for NOVES?
3. How is the appropriate recipient emergency services system (e.g., PSAP) determined?
4. What are the implications due to roaming?
5. Are there any implications to hand over between access networks?
6. Are there any implications due to the subscriber crossing a PSAP boundary during NOVES communications (e.g., subsequent text messages should go to the same PSAP)?
7. Do multiple communication streams (e.g., voice, text, video emergency services) need to be associated together?
8. What types of “call-back” capabilities are required?
9. What are the load impacts of NOVES in the case of a large scale emergency event or malicious use?

NOVES will be applicable to GPRS (GERAN, UTRAN) and to EPS (GERAN, UTRAN, E-UTRAN and non-3GPP). The content may be transmitted between the subscribers and the emergency services which might bring new security issues. Therefore, the security impacts need to be studied.

You can spend your weekend reading the 3GPP Study Item TR 22.871: Study on Non-Voice Emergency Services (Release 11).

A word of caution, the name NOVES may be changed in future as Emergency agencies in Europe have an objection to the name. See here and here.

Friday, 11 February 2011

Smarter Cars of the Future

We all know that cars are getting smarter. Back in Oct., Google unveiled the cars that can drive by themselves. I am sure they will make our life much better and we will be able to catch on the sleep at early morning commute.

Then there were quite a few futuristic cars at the CES 2011 last month. One such video is embedded below.




The following is a summary from the an IEEE article:

Cars have been getting smarter for years, studded with suites of sensors and supporting electronics aimed at keeping them from crashing. But entertainment and convenience have rapidly caught up to safety as the impetus for new in-car electronics development. Because automakers typically spend three years developing and producing new cars—and new gadget candy to go with them—they’ve found themselves constantly playing catch-up with consumer electronics and consumer expectations. So car companies have teamed up with the makers of smartphone software platforms to integrate a spectacular array of apps designed for handsets with cars’ digital dashboards, center consoles, and speaker systems.

Take for instance Ford’s new Focus all-electric vehicle, which made a big splash at the 2011 International Consumer Electronics Show in Las Vegas last month. It features a software application called MyFord Mobile.

The app, which runs on Ford’s proprietary Sync platform and is compatible with the BlackBerry, iPhone, and Android devices, links the car with the driver’s smartphone and home computer. The software lets the driver listen to a smartphone’s music library and lets passengers watch movies or TV shows. It delivers information such as when electricity prices are at their lowest (to allow for the cheapest battery recharging) and where the nearest charging stations are. And it allows a smartphone to function as a remote control, by means of a connection to cloud-based servers. This remote communication lets the handset keep tabs on the car’s location and the batteries’ state of charge. It will also let the driver start the Focus EV from indoors on a blustery January morning, then step into a car whose seats and steering wheel are already warm. The MyFord Mobile app lets the driver remotely start the car, turn on the heater or air conditioner, or unlock the doors from anywhere in the world (including beneath the bedcovers).

And because the system differentiates one driver’s key from another’s, it presents information on the reconfigurable 4-inch screens on either side of the speedometer in the current driver’s preferred color and style. The state of charge, for example, could be shown as a percentage of the full charge, as an estimate of the remaining miles before recharging, or as a simple bar that gets shorter as the batteries’ energy is consumed. This differentiation also works for utility and entertainment options; it automatically queues up driver A’s list of radio station presets, favorite mobile apps, and preferred display options for the 8-inch center console touch screen. Because MyFord Mobile links the Focus to the driver’s handset, it can also access his or her contact list for hands-free calling and read out e-mails and texts through the car’s speakers.

Ford is trying to position itself as a technological leader in the automotive industry with MyFord Mobile and Sync AppLink Voice Control, which puts the driver in control of all the Sync system’s capabilities via voice commands, but it has stiff competition from the likes of Mercedes-Benz, Continental, and Toyota. Launched by Mercedes-Benz in November 2009, the Mbrace system, designed and engineered by Hughes Telematics of Atlanta, was the first telematics service on the market to give smartphones the power to remotely lock, unlock, or locate a car. It didn’t signal a revolution in the way the average driver interacts with his or her vehicle because when the German luxury vehicle maker offers a new technology or set of features, there is usually a multiyear wait for them to trickle down to cars whose sticker prices aren’t stratospheric.

The second generation of Mbrace debuted last September. It introduced Mercedes-Benz Concierge, which not only opens the car to information from the outside but also makes some car-based information and entertainment options portable. The Mbrace Mobile Application 2.0 gives iPhone and Blackberry users single-phone-number access to recommendations for nearby entertainment and restaurant options, directions, traffic updates, and more, whether the person is in the car or not. The concierge then sends destination information to the smartphone or directly to the in-vehicle navigation system. With the Mbrace system’s latest wrinkle, the Drive2Friend service, the driver can dictate a friend’s mobile number and the app sends a text message reporting that the driver is trying to find the person. The friend has the option of allowing his or her location to be sent back to the car via cellular triangulation.

While Ford was showing off its wares at CES, Continental was also there showcasing the Android-based AutoLinQ system, which lets the driver connect to the car in three ways.

AutoLinQ’s Mobile View lets you to send text messages to your car; the smart vehicle can text you back with information such as its location. In this demo [Flash video], a smartphone user is shown making a remote inquiry about the status of his car. Mobile View reports that the sunroof is open and offers the option to close it or ignore the warning. When he taps Close on the handset’s touch screen, the sunroof’s glass panel glides shut. This type of call-and-response vehicle update also tells whether doors are closed and locked and whether the headlights or interior lights are on. Mobile View doesn’t wait for a query to alert the driver when the alarm is triggered, the battery is depleted, the air bag has been activated, or the internal temperature of the car is too high or low. And like MyFord Mobile, it turns the smartphone into a remote control for locking and unlocking the doors, starting the engine, flashing the lights, and more.

AutoLinQ’s Home View lets you download apps and configure vehicle settings from your home computer. Clickable tabs at the bottom of the Home View screen let the car owner move through screens showing a wealth of data on the car’s status, driver preferences, navigation information, and applications that can be downloaded or fine-tuned. The status menu tells whether the ignition is on and displays the fuel and motor oil levels, the pressure for each of the four tires, and much, much more.

Car View, in AutoLinQ, is for updating features from the driver’s seat. Car View provides the same information as Home View but lets the driver use the center console touch screen to download apps on the fly that provide better control of the car and the ability to remotely manipulate electronic devices back home. An app that sends an alert when a game or match in the driver’s favorite sport is about to appear on television also gives the option to activate a digital video recorder at home, pull up a Web site featuring periodic updates about the game, or listen to play-by-play on the radio.

Continental is also designing unique apps that will enhance vehicle performance. For instance, the Filling Assistant will detect underinflated tires and notify the driver. When the driver goes to inflate the tires, the Filling Assistant will report pressure information to the driver’s smartphone and honk the car’s horn or flash its lights to indicate when a tire has enough air.

Not to be left out, Toyota, the world’s leading automaker, debuted the QNX-based Entune at CES 2011. Entune is an upgradable suite of entertainment, navigation, and information functions. "Consumers have grown accustomed to having the world at their fingertips through their mobile phones," says Jon Bucci, vice president of Toyota’s advanced technology department, who notes that putting them in the car is a natural evolution.

After downloading the Toyota Entune app to a handset and syncing it with the Toyota vehicle, the driver can begin accessing content and services, including Bing for Web navigation and OpenTable, which can make reservations at any one of 15 000 restaurants, with directions sent seamlessly to the navigation system and information appearing on the center console. Entune also lets a driver get customizable real-time traffic updates, sports, weather, stocks, and information on prices at local fueling stations. The system doesn’t forget music, which has almost always been a part of the driving experience. Entune includes Iheartradio, which delivers roughly 750 local radio stations at the touch of a button.

The tide of apps extending handset capabilities to cars will only continue to rise. ABI Research, in Oyster Bay, N.Y., reports that the number of users of automotive apps will increase from 1.4 million in 2010 to more than 28 million by 2015. And according to Global Industry Analysts, the vehicle telematics market is expected to reach US $11.2 billion by 2015.

You can read the complete article here.

In other news, Robots in future will have their own Internet and content like Wikipedia, etc. Does anyone else remember 'The Terminator'?

Thursday, 10 February 2011

QoS Control based on Subscriber Spending Limits (QOS_SSL)

Quality of Service (QoS) is very important in LTE/LTE-A and the operators are taking extra efforts to maintain the QoS in the next generation of networks. They are resorting in some cases to Deep packet Inspections (DPI) based controlling of packets and in some cases throttling of data for bandwidth hogs.

The following is from a recent 4G Americas report I blogged about here:

This work item aims to provide a mechanism to allow a mobile operator to have a much finer granularity of control of the subscriber’s usage of the network resources by linking the subscriber’s data session QoS with a spending limit. This gives the operator the ability to deny a subscriber access to particular services if the subscriber has reached his/her allocated spending limit within a certain time period. It would be useful if, in addition, the bandwidth of a subscriber’s data session could be modified when this spending level is reached. This could be done depending on, for example, the type of service being used by the subscriber, the subscriber’s spending limit and amount already spent and operator’s charging models. This allows the operator to have an additional means of shaping the subscriber’s traffic in order to avoid subscribers monopolizing the network resource at any given time. Since support for roaming scenarios is needed, the possibility to provide support for roaming subscribers without having dedicated support in the visited network is needed.

Upon triggers based on the operator’s charging models, the subscriber could be given the opportunity to purchase additional credit that increases the spending limit.

The objective of this study is to provide use cases/service requirements and specs that allow:
* Modification of QoS based on subscriber’s spending limits
* Enforcing of spending limits for roaming subscribers without having dedicated support in the visited network

For further details see: 3GPP TS 22.115 Service aspects; Charging and billing (Release 11)

Wednesday, 9 February 2011

FlashLinq: A P2P Network For Nearby Phones

Looks like the new technologies and enhancements just keep coming.

Following from MobileCrunch:

Imagine being at a concert. As the band wraps up their last song, the lead singer takes the mic and says: “Thanks for coming out everyone! Just for being here, we’re giving you all an exclusive track from our upcoming CD. It should be available on the local wireless network… now!”

Generally, pulling off something like this would be nigh impossible. You’d need a pretty intense wireless infrastructure to handle thousands of freebie-hungry concert goers connecting at once, and then an even beefier backbone to handle the actual transfer. That’s where Qualcomm’s new localized P2P network technology, FlashLinq, comes into play.

As Qualcomm puts it, FlashLinq “enables devices to discover each other automatically and continuously, and to communicate, peer-to-peer, at broadband speeds without the need for intermediary infrastructure.”

In other words, it’ll build a wireless network between FlashLinq-enabled devices, allowing those devices to pass data (like the theoretical exclusive track mentioned above) without some monstrous server doing all the heavy lifting. Qualcomm says

“But wait!” you say, “Isn’t this what WiFi Direct was built for?”.

Yep — the key difference here is that while WiFi Direct can share files between devices, FlashLinq can do that and share connectivity to a cellular network. Nice idea for those situations when only a handful of people in a big crowd can actually manage to pull down any data, right?

So, when can we expect this tech to roll out? Not for a while. Qualcomm’s working with South Korea’s SK Telecom to test out the tech, with trials beginning later this year. If those go well, Qualcomm will have the task of convincing other hardware partners to build this tech into their new gear.

A presentation on FlashLinq below:

Tuesday, 8 February 2011

VoLTE: Semi-Persistent Scheduling (SPS) and TTI Bundling

The following is from the recently released 4G Americas paper '4G Mobile Broadband Evolution: 3GPP Release-10 and beyond:

With the support of emergency and location services in Rel-9, interest in Voice over LTE (VoLTE) has increased. This is because the Rel-9 enhancements to support e911 were the last step to enable VoLTE (at least in countries that mandate e911) since the Rel-8 specifications already included the key LTE features required to support good coverage, high capacity/quality VoLTE. There are two main features in Rel-8 that focus on the coverage, capacity and quality of VoLTE: Semi-Persistent Scheduling (SPS) and TTI Bundling.

SPS is a feature that significantly reduces control channel overhead for applications that require persistent radio resource allocations such as VoIP. In LTE, both the DL and UL are fully scheduled since the DL and UL traffic channels are dynamically shared channels. This means that the physical DL control channel (PDCCH) must provide access grant information to indicate which users should decode the physical DL shared channel (PDSCH) in each subframe and which users are allowed to transmit on the physical UL shared channel (PUSCH) in each subframe. Without SPS, every DL or UL physical resource block (PRB) allocation must be granted via an access grant message on the PDCCH. This is sufficient for most bursty best effort types of applications which generally have large packet sizes and thus typically only a few users must be scheduled each subframe. However, for applications that require persistent allocations of small packets (i.e. VoIP), the access grant control channel overhead can be greatly reduced with SPS.

SPS therefore introduces a persistent PRB allocation that a user should expect on the DL or can transmit on the UL. There are many different ways in which SPS can setup persistent allocations, and Figure below shows one way appropriate for VoLTE. Note that speech codecs typically generate a speech packet every 20 ms. In LTE, the HARQ interlace time is 8 ms which means retransmissions of PRBs that have failed to be decoded can occur every 8 ms. Figure below shows an example where a maximum of five total transmissions (initial transmission plus four retransmissions) is assumed for each 20 ms speech packet with two parallel HARQ processes. This figure clearly shows that every 20 ms a new “first transmission” of a new speech packet is sent. This example does require an additional 20 ms of buffering in the receiver to allow for four retransmissions, but this is generally viewed as a good tradeoff to maximize capacity/coverage (compared to only sending a maximum of two retransmissions).

The example in Figure above can be applied to both the DL and UL and note that as long as there are speech packets arriving (i.e. a talk spurt) at the transmitter, the SPS PRBs would be dedicated to the user. Once speech packets stop arriving (i.e. silence period), these PRB resources can be re-assigned to other users. When the user begins talking again, a new SPS set of PRBs would be assigned for the duration of the new talkspurt. Note that dynamic scheduling of best effort data can occur on top of SPS, but the SPS allocations would take precedent over any scheduling conflicts.


TTI bundling is another feature in Rel-8 that optimizes the UL coverage for VoLTE. LTE defined 1 ms subframes as the Transmission Time Interval (TTI) which means scheduling occurs every 1 ms. Small TTIs are good for reducing round trip latency, but do introduce challenges for UL VoIP coverage. This is because on the UL, the maximum coverage is realized when a user sends a single PRB spanning 180 kHz of tones. By using a single 180 kHz wide PRB on the UL, the user transmit power/Hz is maximized. This is critical on the UL since the user transmit power is limited, so maximizing the power/Hz improves coverage. The issue is that since the HARQ interlace time is 8 ms, the subframe utilization is very low (1/8). In other words, 7/8 of the time the user is not transmitting. Therefore, users in poor coverage areas could be transmitting more power when a concept termed TTI bundling (explained in the next paragraph) is deployed.

While it’s true that one fix to the problem is to just initiate several parallel HARQ processes to fill in more of the 7/8 idle time, this approach adds significant IP overhead since each HARQ process requires its own IP header. Therefore, TTI bundling was introduced in Rel-8 which combined four subframes spanning 4 ms. This allowed for a single IP header over a bundled 4 ms TTI that greatly improved the subframe utilization (from 1/8 to 1/2) and thus the coverage (by more than 3 dB).

Martin Sauter puts it in a simpler way in his blog as follows: The purpose of TTI Bundling is to improve cell edge coverage and in-house reception for voice. When the base station detects that the mobile can't increase it's transmission power and reception is getting worse it can instruct the device to activate TTI bundling and send the same packet but with different error detection and correction bits in 2, 3 or even 4 consecutive transmit time intervals. The advantage over sending the packet in a single TTI and then detecting that it wasn't received correctly which in turn would lead to one or more retransmissions is that it saves a lot of signaling overhead. Latency is also reduced as no waiting time is required between the retransmissions. In case the bundle is not received correctly, it is repeated in the same way as an ordinary transmission of a packet. Holma and Toskala anticipate a 4dB cell edge gain for VoIP with this feature which is quite a lot. For details how the feature is implemented have a look at 3GPP TS 36.321.

A whitepaper explaining the concepts of TTI Bundling is available on Slideshare here.

Monday, 7 February 2011

'EU-Alert' in Release-11

In the recently concluded 3GPP CT-50 in Istanbul, EU-Alert was adopted as part of Rel-11. The EU-Alert is introduced under Public Warning System (PWS) in parallel with Earthquake and Tsunami Warning System (ETWS).

PWS was introduced in Rel-9 and I blogged about it here. ETWS has been around since Rel-8 and was blogged here.

In fact EU-Alert is sent as part of the Cell Broadcast Message (CBS) using new identifiers. For more details see 3GPP TS 23.401.

The following is an old video from CHORIST project, which was instrumental in providing details of working of this EU-Alert system.




Also Read: Commercial Mobile Alert System (CMAS) here.

Thursday, 3 February 2011

4G Mobile Broadband Evolution: 3GPP Release-10 and Beyond

New Report from 4G Americas:

4G Mobile Broadband Evolution: 3GPP Release 10 and Beyond - HSPA+ SAE/LTE and LTE-Advanced provides detailed discussions of Release 10, including the significant new technology enhancements to LTE/EPC (called LTE-Advanced) that were determined in October 2010 to have successfully met all of the criteria established by the International Telecommunication Union Radiotelecommunication Sector (ITU-R) for the first release of IMT-Advanced. IMT-Advanced, which includes LTE-Advanced, provides a global platform on which to build next generations of interactive mobile services that will provide faster data access, enhanced roaming capabilities, unified messaging and broadband multimedia. The paper also provides detailed information on the introduction of LTE-Advanced and the planning for Release 11 and beyond. Release 10 is expected to be finalized in March 2011, while work on Release 11 will continue through the fourth quarter of 2012.

White paper embedded below and is available to view and download from the 3G4G website.


Wednesday, 2 February 2011

Making small purchases simpler with Ericsson IPX

Yesterday a colleague made me aware of this Ericsson's IPX SMS based payment system that looks like a competitor to the NFC technology and doesn't involve any additional chip/hardware. Here is a video:



From Ericsson's website:

Ericsson Internet Payment Exchange (IPX) is a leading mobile aggregator, providing delivery and billing services, via SMS, MMS, web and online mobile billing, to more than 2 billion mobile subscribers across 26 countries. Ericsson IPX also brokers location information in selected countries and Ericsson IPX Messaging provides reach to 96% of all mobile subscribers worldwide with SMS. Ericsson IPX customers are companies who offer digital content, mobile voting & directory information and enterprises offering mobile marketing, communities and banking.

Now, we all love SMS and we have to admit that its the simplest of technology and even the most primitive phone nowadays support it but there could be scenarios when this can be a bit of a problem:

1. SMS can sometimes be delayed if a particular cell is overloaded, etc. So how long do we have to stand in front of the machine?
2. If say for 2-3 mins we do not receive an indication that the machine has a cash, do we send another SMS to cancel the transaction?
3. If we have a problem, do we have a support number to call to? How much will that cost?
4. If there is a queue of people and someone else wants to purchase something as well, does the next person has to wait till the person before has received the item?
5. If two people have sent an SMS, how do they know whose cash is in the machine now? Do we start putting a Pin as well ?

I agree, this technology could be really useful if you have run out of cash (even if you have NFC chip) and you need to purchase something small.

The other obvious advantage is that you can target advertisement at regular users who are at a particular place at a particular time to make them buy something. Also you can get statistics like what time people tend to purchase, what do they purchase, where, etc.

Anyway, hard for me to see this take off big time.

Tuesday, 1 February 2011

6th ETSI Security Workshop

6th ETSI Security workshop was held last month. There were some very interesting areas of discussion including Wireless/Mobile Security, Smart Grids Security, etc.
All presentations are available to download from here.