TD-SCDMA Politics!

I posted sometime back about China Mobile standards ready to battle the 3G standards. I read this interesting piece in The IET Magazine:

The wait is over for millions of Chinese mobile phone users. Following several years of delays, the government has finally issued the licences that were necessary for the introduction of third-generation cellular services in the country.

As ordered by the Ministry of Industry and Information Technology, each of the nation’s three main operators will have to build and operate a network based on one of the three different standards that were vying for a share of the world’s largest cellular market.

China Mobile (by far the dominant carrier with over 460 million subscribers) will operate on TD-SCDMA, the 3G technology that was developed entirely in the People’s Republic by the Chinese Academy of Telecommunications Technology in collaboration with Datang and Siemens. China Telecom will run on W-CDMA, while China Unicom gets CDMA2000.

Considering how immature TD-SCDMA technology still is - and how discouraging its build-up trials have proved - China Mobile seems to have landed the worst possible deal.

Then again, that was the whole idea of this so-called reorganisation of the country’s telecoms industry. Let the incumbent cellco work on the many problems that will have to be ironed out before TD-SCDMA can be considered a credible 3G alternative, and that should give the two smaller operators enough time to catch up by taking advantage of proven technologies and an established pool of equipment suppliers.

The Chinese government wants a more balanced, more competitive telecoms market, and this should help do the trick. But the move is also likely to have some strange consequences in the relationship between mobile operators and phone makers.

China Mobile faces two different handset-related challenges when it comes to 3G. The first one is qualitative: existing TD-SCDMA phones are technically inferior to those that subscribers have been using in the rest of the world for well over eight years now. The second is quantitative: only 40 or so TD-SCDMA models exist, while China Mobile says it will need several hundred.

So the company is resorting to some unprecedented behaviour for a cellular operator. At the last Mobile World Congress in Barcelona, Wang Jianzhou, the chairman of China Mobile, met with a group of handset vendors (including Nokia, LG, Samsung, Sony Ericsson and some of the Chinese manufacturers) and offered to pay them part of the R&D costs of developing better TD-SCDMA products.

Handset makers have rarely witnessed such generous attitudes from an operator. Even rarer is the fact that the offer is coming from what is now the world’s largest operator. Add to that the unfavourable financial conditions most of these OEMs are enduring and you could safely assume they’ll go and see what they can do to help China Mobile.

You can also read about what TD-SCDMA is here. More about the current status of TD-SCDMA here.

Femtocells Standardization in 3GPP

Femtocells have been around since 2007. Before Femtocells, the smallest possible cell was the picocell that was designed to serve a small area, generally a office or a conference room. With Femtocells came the idea of having really small cells that can be used in houses and they were designed to serve just one home. Ofcourse in my past blogs you would have noticed me mentioning about Super Femtos and Femto++ that can cater for more users in a small confined space, typically a small office or a meeting room but as far as the most common definition is concerned they are designed for small confined spaces and are intended to serve less than 10 users simultaneously.

This blog post is based on IEEE paper on "Standardization of Femtocells in 3GPP" that appeared in IEEE Communications Magazine, September 2009 issue. This is not a copy paste article but is based on my understanding of Femtos and the research based on the IEEE paper. This post only focusses on 3GPP based femtocells, i.e., Femtocells that use UMTS HSDPA/HSPA based technology and an introduction to OFDM based LTE femtocells.

The reason attention is being paid to the Femtocells is because as I have blogged in the past, there are some interesting studies that suggest that majority of the calls and data browsing on mobiles originate in the home and the higher the frequency being used, the less its ability to penetrate walls. As a result to take advantage of the latest high speed technologies like HSDPA/HSUPA, it makes sense to have a small cell sitting in the home giving ability to the mobiles to have high speed error free transmission. In addition to this if some of the users that are experiencing poor signal quality are handed over to these femtocells, the overall data rate of the macro cell will increase thereby providing better experience to other users.

Each technology brings its own set of problems and femocells are no exception. There are three important problems that needs to be answered. They are as follows:

• Radio interference mitigation and management: Since femtocells would be deployed in adhoc manner by the users and for the cost to be kept down they should require no additional work from the operators point of view, they can create interference with other femtocells and in the worst possible scenario, with the macro cell. It may not be possible initially to configure everything correctly but once operational, it should be possible to adjust the parameters like power, scrambling codes, UARFCN dynamically to minimise the interference.

• Regulatory aspects: Since the mobiles work in licensed spectrum bands, it is required that they follow the regulatory laws and operate in a partcular area in a band it is licensed. This is not a problem in Europe where the operators are given bands for the whole country but in places like USA and India where there are physical boundaries within the country for the allocation of spectrum for a particular operator. This brings us to the next important point.

• Location detection: This is important from the regulatory aspect to verify that a Femtocell can use a particular band over an area and also useful for emergency case where location information is essential. It is important to make sure that the user does not move the device after initial setup and hence the detection should be made everytime the femto is started and also at regular intervals.

3GPP FEMTOCELLS STANDARDIZATION

Since the femtocells have been available for quite a while now, most of them do not comply to standards and they are proprietary solutions. This means that they are not interoperable and can only work with one particular operator. To combat this and to create economy of scale, it became necessary to standardise femtocells. Standardized interfaces from the core network to femtocell devices can potentially allow system operators to deploy femtocell devices from multiple vendors in a mix-and-match manner. Such interfaces can also allow femtocell devices to connect to gateways made by multiple vendors in the system operator’s core network (e.g., home NodeB gateway [HNB-GW] devices).

In 2008, Femto Forum was formed and it started discussion on the architecture. From 15 different proposals, consensus was reached in May over the Iuh interface as shown below.

There are two main standard development organizations (SDOs) shaping the standard for UMTS-related (UTRAN) femto technology: 3GPP and The Broadband Forum (BBF).
More about 3GPP here. BBF (http://www.broadbandforum.org) was called the DSL Forum until last year. As an SDO to meet the needs of fixed broadband technologies, it has created specifications mainly for DSL-related technologies. It consists of multiple Working Groups. The Broadband Home WG in particular is responsible for the specification of CPE device remote management. The specification is called CPE wide area network (WAN) Management Protocol (CWMP), which is commonly known by its document number, TR-069.

There are several other important organisations for femto technology. The two popular ones are the Femto Forum (www.femtoforum.org) and Next Generation Mobile Network (NGMN).

3GPP has different terminology for Femtocells and components related to that. They are as follows:

Generic term: Femtocell
3GPP Term: home NodeB (HNB)
Definition: The consumer premises equipment (CPE) device that functions as the small-scale nodeB by interfacing to the handset over the standard air interface (Uu) and connecting to the mobile network over the Iuh interface.

Generic term: FAP Gateway (FAP-GW) or Concentrator
3GPP Term: home NodeB gateway (HNB-GW)
Definition: The network element that directly terminates the Iuh interface with the HNB and the existing IuCS and IuPS interface with the CN. It effectively aggregates a large number of HNBs (i.e., Iuh interface) and presents it as a single IuCS/PS interface to the CN.

Generic term: Auto-Configuration Server (ACS)
3GPP Term: home NodeB management system (HMS)
Definition: The network element that terminates TR-069 with the HNB to handle the remote management of a large number of HNBs.

In addition, there is a security gateway (SeGW) that establishes IPsec tunnel to HNB. This ensures that all the Iuh traffic is securely protected from the devices in home to the HNB-GW.
The HNB-GW acts as a concentrator to aggregate a large number of HNBs which are logically represented as a single IuCS/IuPS interface to the CN. In other words, from the CN’s perspective, it appears as if it is connected to a single large radio network controller (RNC). This satisfies a key requirement from 3GPP system operators and many vendors that the femtocell system architecture not require any changes to existing CN systems.

The radio interface between HNB and UE is the standard RRC based air interface but has been modified to incude HNB specific changes like the closed subscriber group (CSG) related information.

Two new protocols were defined to address HNB-specific differences from the existing Iu interface protocol to 3GPP UMTS base stations (chiefly, RANAP at the application layer).

• HNB Application Protocol (HNBAP): An application layer protocol that provides HNB-specific control features unique to HNB/femtocell deployment (e.g., registration of the HNB device with the HNBGW).

• RANAP User Adaptation (RUA): Provides a lightweight adaptation function to allow RANAP messages and signaling information to be transported directly over Stream Control Transport Protocol (SCTP) rather than Iu, which uses a heavier and more complex protocol stack that is less well suited to femtocells operating over untrusted networks from home users (e.g., transported over DSL or cable modem connections).

Figure above is representation of the protocol stack diagram being used in TS 25.467.

Security for femtocell networks consists of two major parts: femtocell (HNB) device authentication, and encryption/ciphering of bearer and control information across the untrusted Internet connection between the HNB and the HNB-GW (e.g., non-secure commercial Internet service). The 3GPP UMTS femtocell architecture provides solutions to both of these problems. 3GPP was not able to complete the standardization of security aspects in UMTS Release 8; however, the basic aspects of the architecture were agreed on, and were partially driven by broad industry support for a consensus security architecture facilitated in discussions within the Femto Forum. All security specifications will be completed in UMTS Release 9 (targeted for Dec. 2009).

FEMTOCELL MANAGEMENT

Management of femtocells is a very big topic and very important one for the reasons discussed above.

The BBF has created CWMP, also referred to as TR-069. TR-069 defines a generic framework to establish connection between the CPE and the automatic configuration server (ACS) to provide configuration of the CPE. The messages are defined in Simple Object Access Protocol (SOAP) methods based on XML encoding, transported over HTTP/TCP. It is flexible and extensive enough to incorporate various types of CPE devices using various technologies. In fact, although TR-069 was originally created to manage the DSL gateway device, it has been adopted by many other types of devices and technologies.

The fundamental functionalities TR-069 provides are as follows:

• Auto-configuration of the CPE and dynamic service provisioning

• Software/firmware management and upgrade

• Status and performance monitoring

• Diagnostics

The auto-configuration parameters are defined in a data model. Multiple data model specifications exist in the BBF in order to meet the needs of various CPE device types. In fact, the TR-069 data model is a family of documents that has grown over the years in order to meet the needs of supporting new types of CPE devices that emerge in the market. In this respect, femtocell is no exception. However, the two most common and generic data models are:

• TR-098: “Internet Gateway Device Data Model for TR-069”

• TR-106: “Data Model Template for TR-069-Enabled Devices”

HAND-IN AND FEMTO-TO-FEMTO HANDOVERS

The 3GPP specifications focused on handovers in only one direction initially — from femtocell devices to the macrocellular system (sometimes called handout). A conscious decision was made to exclude handover from the macrocellular system to the femtocell devices (sometimes called macro to femtocell hand-in). This decision was driven by two factors:

• There are a number of technical challenges in supporting hand-in with unmodified mobile devices and core network components.

• The system operator requirements clearly indicate that supporting handout is much more important to end users.

Nonetheless, there is still a strong desire to develop open, interoperable ways to support handin in an efficient and reliable manner, and the second phase of standards in 3GPP is anticipated to support such a capability.

NEXT-G EFFORTS

3GPP Release 8 defines the over-the-air radio signaling that is necessary to support LTE femtocells. However, there are a number of RAN transport and core network architecture, interface, and security aspects that will be addressed as part off 3GPP’s Release 9 work efforts. While it is preliminary as of the publication of this article, it seems highly likely that all necessary RAN transport and core network work efforts for LTE femtocells will be completed in 3GPP Release 9 (targeted for completion by the end of 2009).

3GPP STANDARDS ON FEMTOCELLS

[1] 3GPP TS 25.331: RRC

[2] 3GPP TS 25.367: Mobility Procedures for Home NodeB (HNB); Overall Description; Sage 2

[3] 3GPP TS 25.467: UTRAN Architecture for 3G Home NodeB; Stage 2

[4] 3GPP TS 25.469: UTRAN Iuh Interface Home NodeB (HNB) Application Part (HNBAP) Signaling

[5] 3GPP TS 25.468: UTRAN Iuh Interface RANAP User Adaption (RUA) Signaling

[6] 3GPP TR 3.020: Home (e)NodeB; Network Aspects -(http://www.3gpp.org/ftp/tsg_ran/WG3_Iu/R3_internal_TRs/R3.020_Home_eNodeB/)

[7] 3GPP TS 25.104: Base Station (BS) Radio Transmission and Reception (FDD)

[8] 3GPP TS 25.141: Base Station (BS) Conformance Testing (FDD)

[9] 3GPP TR 25.967: FDD Home NodeB RF Requirements

[10] 3GPP TS 22.011: Service Accessibility

[11] 3GPP TS 22.220: Service Requirements for Home NodeB (HNB) and Home eNodeB (HeNB)

[12] 3GPP TR 23.830: Architecture Aspects of Home NodeB and Home eNodeB

[13] 3GPP TR 23.832: IMS Aspects of Architecture for Home NodeB; Stage 2

[14] 3GPP TS 36.300: E-UTRA and E-UTRAN; Overall Description; Stage 2

[15] 3GPP TR 33.820: Security of H(e)NB 3GPP TR 32.821: Telecommunication Management; Study of Self-Organizing Networks (SON) Related OAM Interfaces for Home NodeB

[16] 3GPP TS 32.581: Telecommunications Management; Home Node B (HNB) Operations, Administration, Maintenance and Provisioning (OAM&P); Concepts and Requirements for Type 1 Interface HNB to HNB Management System (HMS)

[17] 3GPP TS 32.582: Telecommunications Management; Home NodeB (HNB) Operations, Administration, Maintenance and Provisioning (OAM&P); Information Model for Type 1 Interface HNB to HNB Management System (HMS)

[18] 3GPP TS 32.583: Telecommunications Management; Home NodeB (HNB) Operations, Administration, Maintenance and Provisioning (OAM&P); Procedure Flows for Type 1 Interface HNB to HNB Management System (HMS)

[19] 3GPP TS 32.584: Telecommunications Management; Home NodeB (HNB) Operations, Administration, Maintenance and Provisioning (OAM&P); XML Definitions for Type 1 Interface HNB to HNB Management System (HMS)

I would strongly recommend reading [3] and [6] for anyone who wants to gain better understanding of how Femtocells work.

Industry's first LTE Comformance test submitted for approval

Anite has submitted the first LTE test case 8.1.2.1 based on the conformance test specification 36.523-1. The test case was debugged using the LG Electronics LE03 UE.

This is in a way good news as the industry is moving forward at an amazing speed. The Release-8 of LTE was finalised in reality in March 09 (or Dec. 08 for some specs).

Anite has partnered with Agilent for the conformance testing and this release of TC's is a good way forward towards proving industry leadership.

Looking at the latest test cases that have been submitted, it seems another couple of tests 7.1.1.1 and 8.1.1.1 have been submitted as well.

People who are interested in technical details can look at the logs submitted and get the details of the messages that I have specified in the message flow earlier here.

====== Edited after post =====

Here is their press release which seems to have come after my blog :)

Anite, a global leader in testing technology for the wireless industry, and LG Electronics (LG), a global leader and technology innovator in mobile communications, today announced the successful verification of the industry’s first LTE protocol conformance test cases. Anite and LG Electronics have made the results from their groundbreaking work available to the members of the 3GPP standards body, so that the entire mobile industry may benefit from this milestone achievement.

Conformance testing is fundamental in leading-edge technologies, such as LTE, because it ensures that new handsets and data cards deliver both the applications and services anticipated by the end user and the ability to work seamlessly with existing users and networks. LG uses Anite’s LTE solution – which provides a suite of development tools for UE designers – to develop their devices in advance of LTE networks being available, ensuring these meet the industry’s rigorous certification requirements during the earliest stages of their development cycle.

The new tests build upon Anite’s comprehensive portfolio for all leading 3GPP protocol technologies from GSM through EDGE and WCDMA to the latest HSPA+ standards. Anite’s unique blend of software-only host and target test solutions for 2G, 3G and LTE technologies allows developers to adopt a total end-to-end test philosophy for all of their wireless testing needs, reducing both their time and cost to market.

"LTE device certification is essential in ensuring that next generation LTE wireless devices meet customer expectations. Working with LG is speeding the availability of the first LTE test cases to LTE developers, enabling the wireless industry to deploy the technology successfully and more quickly," said Paul Beaver, 3GPP Director, Anite. “Our customers can be confident that investing in Anite’s products will meet their conformance testing needs, maximising their test system utilisation and return on investment.”

Twitter could be very useful ;)

LTE Packet Call Signalling example

Available here for anyone interested in the flow.

Interesting stats from Tomi Ahonen's talk on 'the next 4 Billion Mobile Subscribers'

Tomi has posted an interesting blog titled "What do I mean, by 'next four billion'?". Its an interesting read. As usual there are lots of interesting facts that i am posting here for my own reference :)

• 4 Billion: Global count of mobile subscribers at the start of 2009
• 480 million newspapers printed daily
• 800 million automobiles registered on the planet
• 1.1 billion personal computers including all desktops, laptops, notebooks and netbooks
• 1.2 billion fixed landine phones
• 1.4 billion internet users
• 1.5 billion TV sets
• 1.7 billion unique holders of a credit card of any type
• 2.1 billion unique holders of a banking account of any kind
• Total FM Radio worldwide: 3.9 Billion units
• Total human population: 6.7 Billion
• Out of 4 billion total mobile subscribers at the end of last year, 3.1 billion were unique phone owners, and the remaining 900 million were second and third subscriptions
• Europe today is at 115% penetration rate
• USA is past 90% penetratation rate per capita
• Hong Kong, Italy, Israel, Portugal and Singapore are past 130% penetration levels - and still growing
• The planet is at 64% penetration rate now
• The UN estimates that the amount of illiterate people on the planet is 800 million
• SMS has 3.1 billion active users
• MMS has 1.4 billion active users with over 3 billion phones that can receive MMS messages

Thank you Tomi for these interesting facts

Beyond Voice: New uses for mobile phones could launch another wave of development

The Economist recently published a special report on Telecoms in Emerging markets which is available here. The following is an extract from that.

In a field just outside the village of Bumwambu in eastern Uganda, surrounded by banana trees and cassava, with chickens running between the mudbrick houses, Frederick Makawa is thinking about tomatoes. It is late June and the rainy season is coming to an end. Tomatoes are a valuable cash crop during the coming dry season and Mr Makawa wants to plant his seedlings as soon as possible. But Uganda’s traditional growing seasons are shifting, so he is worried about droughts or cash foods that could destroy his crop. Michael Gizamba, a local villagephone operator, offers to help using Farmer’s Friend, an agricultural information service. He sends a text message to ask for a seasonal weather forecast for the region. Before long a reply arrives to say that normal, moderate rainfall is expected during July. Mr Makawa decides to plant his tomatoes.

The Farmer’s Friend service accepts text message queries such as "rice aphids", "tomato blight" or "how to plant bananas" and dispenses relevant advice from a database compiled by local partners. More complicated questions ("my chicken’s eyes are bulging") are relayed to human experts, who either call back within 15 minutes or, with particularly diffcult problems, promise to provide an answer within four days. These answers are then used to improve the database.

Farmer’s Friend is one of a range of phone based services launched in June by MTN, Google and the Grameen Foundation’s "Application Laboratory", or AppLab. As well as disseminating advice in agriculture, provided by the Busoga Rural Open Source and Development Initiative, the new services also provide health and market information. The Clinic Finder service points people to nearby clinics, and the Health Tips service explains the symptoms of common diseases.

Lastly there is Google Trader, a textbased system that matches buyers and sellers of agricultural produce and commodities. Sellers send a message to say where they are and what they have to offer, which will be available to potential buyers within 30km for seven days. Mr Makawa says his father used the service to look for a buyer for some pigs, which he sold to pay school fees. These services cost 110 shillings ($0.05) a time, the same as a standard text message, except for Google Trader, which costs double that. In their first five weeks the services received a total of more than 1m queries.

As with the Village Phone project, Grameen is trying to establish a model that can be scaled up and replicated in other countries. Offering agricultural and health information is more diffcult than offering a phone service, however, because such information must be localised and must take cultural di?erences into account.

Grameen’s collaboration with MTN and Google in Uganda is just one of dozens of services across the developing world that offer agricultural, market and health information via mobile phones. In India, for example, farmers can sign up for Reuters Market Lite, a textbased service that is available in parts of India. Its 125,000 users pay 200 rupees ($4.20) for a threemonth subscription, which provides them with local weather and price information four or five times a day. Many farmers say that their profits have gone up as a result.

Tata Consultancy Services, an Indian operator, offers a service called mKrishi which is similar to Farmer’s Friend, allowing farmers to send queries and receive personalised advice. "The rural population is willing to pay substantial subscription fees to get this information multiple times a day", says Kunal Bajaj of BDA. There have been lots of pilot schemes in the past, he says, but commercial offerings are now beginning to gain ground.

Nokia, the world’s largest handsetmaker, launched its own information service, Nokia Life Tools, in India in June. In addition to education and entertainment, it provides agricultural information, such as prices, weather data and farming tips, that can be called up from special menus on some Nokia handsets. The basic service costs 30 rupees a month, and a premium service which provides detailed local crop prices in ten states is available at twice that price. "It is in its early stages, but it has resonated extremely well with its target audience," says OlliPekka Kallasvuo, Nokia’s chief executive.

Services to help farmers have been most widely adopted in China, where China Mobile offers a service called Nong Xin Tong in conjunction with the agriculture ministry, as part of its push into rural areas. It has already signed up 50m users and is aiming for 100m within three years. The service provides news, weather information and details of farming related government policies.

China Mobile also runs a website, 12582.com, that sends farmers information about planting techniques, pest management and market prices. The service, which costs two yuan ($0.30) a month, sends out 13m text messages a day and has over 40m users. There are dozens of other examples across the developing world.

TradeNet, launched in Ghana in 2005, now links buyers and sellers of agricultural products in nine African countries; CellBazaar provides a textbased classified ads service in Bangladesh.
Mobile phones are also being used in health care. Oneway text alerts, sent to everyone in a particular area, can be used to raise awareness of HIV; sending daily text messages to patients can help them remember to take their drugs for tuberculosis or HIV. Mobile phones can be used to gather health information in the field faster and more accurately than paper records and help with the management of drug stocks. Cameraphones are used to send pictures to remote specialists for diagnosis.

Quantifying the benefits of agricultural and health services is hard, and such services are still in their early days in much of the world. The mobile service that is delivering the most obvious economic benefits is money transfer, otherwise known as mobile banking (though for technical and regulatory reasons it is not, strictly speaking, banking). It has grown out of the widespread custom of using prepaid calling credit as an informal currency.

Suppose you want to send money from the city back to your family in the country. You could travel to the village and deliver I’m not selling for that the cash in person, but that takes time and money. Or you could ask an intermediary, such as a bus driver, to deliver the money, but that can be risky. More simply, you could buy a topup voucher for the amount you want to transfer (say, $10) and then call the villagephone operator or shopkeeper in your family’s village and read out the code on the voucher. The credit will be applied to the phone of the shopkeeper, who will hand cash to your family, minus a commission of 10-20%. In some countries, where airtime can be transferred directly from one phone to another by text message, the process is even simpler: load credit onto your phone, then send it to someone on the spot who in return gives cash to your intended recipient.

These methods became so widespread that some companies decided to set up mobile payment systems that allow real money, rather than just airtime, to be transferred from one user to another by phone. Once you have signed up, you pay money into the system by handing cash to an agent (usually a mobile operator’s airtime vendor), who credits the money to your mobilemoney account. You can withdraw money by visiting another agent, who checks that you have su?cient funds before debiting your account and handing over the cash.

You can also send money to other people, who will be sent a text message containing a special code that can be taken to an agent to withdraw cash. This allows cash to be sent from one place to another quickly and easily. The biggest successes in this field so far have been Gcash and Smart Money in the Philippines, Wizzit in South Africa, Celpay in Zambia and, above all, MPESA in Kenya, which has become the most widely adopted mobile money scheme in the world.

Launched in 2007 by Safaricom, Kenya’s largest mobile operator, it now has nearly 7m users. Not bad for a country of 38m people, 18.3m of whom have mobile phones. MPESA’s early adopters were young, male urban migrants who used it to send money home to their families in the country. But it has since become wildly popular and is used to pay for everything from school fees to taxis (drivers like it because it means they are carrying less cash around). Roughly $2m is transferred through the system each day, with an average amount of $20. ?In markets in Kenya, stallholders are happy to take MPESA payments.

"It’s pretty dramatic," says Bob Christen, head of the "Financial Services for the Poor" initiative at the Bill & Melinda Gates Foundation.

MTN’s launch of a mobile money service in Uganda in March 2009, in partnership with Stanbic Bank, provides further cause for optimism. MTN backed up its launch with a huge marketing campaign based around the simple idea of sending money home, as Safaricom had previously done in Kenya. After three months 60% of the population had heard of the service, a level of awareness that MPESA took a year to achieve, according to MTN. After four months the service had signed up 82,000 users. Of the $5.1m transferred in that period, half was in the fourth month, indicating a rapid take-off. MTN plans to increase the number of outlets that can handle mobile money to 5,000 by early 2010. MTN’s apparent success in Uganda seems to suggest that Kenya may not be a one-off after all. After fine-tuning its technology and procedures in Uganda, MTN plans to introduce the service in 20 other African and Middle Eastern countries; it has already launched in Ghana. Meanwhile Zain, which operates in several African markets, has started its own mobilemoney service, called Zap. According to CGAP, there will be over 120 mobilemoney schemes in developing countries by the end of 2009, more than double the number in 2008. By 2012, it predicts, some 1.7 billion people will have a mobile phone but no bank account, and 20% of them will be using mobile money.

Operators do not expect to make much money from mobile banking, says Mr Okoudjou, but it can help keep customers from defecting to rivals and cut costs by allowing people to top up their airtime directly on their phones, as well as providing wider social and economic benefits that reflect well on operators. Most importantly, he says, mobile banking can help the industry repeat the huge impact made when mobile phones were first introduced. "This is a second wave that can unleash the potential of mobile phones again," he says. "So we need to do this, and we need to do it properly, and we need to do it all over."

OFDMA Femtocells: A Roadmap on Interference Avoidance

Earlier, I have blogged about LTE femtocells being starting point of LTE and how LTE can be better technology than HSPA. In this months IEEE Communications magazine, there is a series of articles on Femtocells. I will try and cover some of these (unless I wander off in some other direction). The first one is titled 'OFDMA Femtocells: A Roadmap on Interference Avoidance'. At the end of this post, I have provided links to the research and the actual paper (in a legal way ;) so if you are not interested in the post and want to directly jump on the actual paper see the end of this post.

There are all kinds of statistics about the number of Femtocells worldwide. There could be upto 70million by 2012. If this happens the big problem would be the interference between Macro and Femtocells and also between Femtos. OFDMA (used in LTE and WiMAX both) Femtocells can handle the interference better than CDMA (UMTS and CDMA2000) Femtocells due to its Intracell interference avoiding properties and robustness to multipath.

So what are the main problems that the operators will face when deploying femtocells? Lets look at some of them:

• Access method: Three different approaches exist namely, Open access, Closed access and Hybrid access which is a mix of both of them. The first two approach has some problems and I have suggested a solution before ;) but the best solution may be to go for Hybrid approach where limited connectivity is available to non-subscribers of the femto.
• Time Synchronisation is another important aspect of OFDMA Femtos. To minimise multi-access interference and for successful handovers, synchronisation between all the Femtos and between Femto and Macro is a must. This should be acheived without any complicated hardware so as to keep the cost down.
• Physical Cell Idendities (PCI) could be a problem because of limited numbers
• Neighbouring cell list, which is restricted to 32 in LTE, could be a problem if too many Femtos are around
• Handovers could also be a problem if the UE keeps jumping between Femtos and macro. One solution could be the use of HCS.

Interference analysis will definitelty play an important part in the rollouts. If not properly managed, could result in dead zones within Macro. Power control Algorithms and Radio Resource Management strategy will help but effective Spectrum allocation technique is needed as well. The diagram above shows different approaches for subchannel allocation in OFDMA femtocells.


The Femtocells would need to be self-configurable and self-optimising. I tried to explain the SON concept earlier which is similar. Self-configuration comes into picture when the Femto is switched on. Once the parameters are adjusted then Self-Optimisation tries to optimise these defaults into something better and more suited to the current environment. Sensing of the environment plays an important part in this. The diagram above shows different approaches being used by different Femtocells. The cheapest approach would ofcourse be the measurement report approach where the phone is made to report the environment. The only problem being that whichever phone was used (automatically selected) will have considerable amount of its battery power used up :)

The team behind this IEEE paper has been doing some excellent research work in the field of femtocells.

There is a book that is under publication and will be available early next year. At the same time if it interests you, you can look at some of their publications including the IEEE one that has been quoted here. Here are all the necessary links:

• The Centre for Wireless Network Design
• Professor Jie Zhang homepage
• David López-Pérez, Research Fellow, homepage
• Femtocells World Summit presentation on Self-organisation of the Subchannel Assignment in OFDMA Femtocells
• OFDMA Femtocells: A Roadmap on Interference Avoidance - IEEE Communications magazine, Sep. 2009
• ICC 2009: Femtocells panel presentation slides

Hope someone finds all this info useful :)

ICC 2009: 3G to 4G: towards full mobility IP services

There are some interesting slides and presentation from the IEEE Communications Society ICC 2009 conference in Dresden, Germany in June 2009. Here is the link to slides from the topic "3G to 4G: towards full mobility IP services".

Let me know if you found it useful.

Paging Permission with Access Control (PPAC) Study in Release 8

A new feature that was studied part of 3GPP Release 8 was PPAC (Paging Permission with Access Control). The aim of this feature was that in an emergency situation, the network can get congested and as a result all access is barred except for emergency services. This can cause problem when the user requires to be contacted but is unreachable.

Lets take Case 1: Disaster risk management office in government calls to emergency responder within disaster areas in order to supply temporary service to the disaster areas.

This should not be a problem because the emergency responder is an authorised user with higher priority of access class and will be able to make and receive calls in the disaster area.



Case2: Ambulance attendant reaches a rescue site in the disaster area but cannot find the person who asked for help originally because of unexpected destruction. The attendant should be able to call him/her in order to make sure where he/she is.

Case3: Firefighter is at a scene of fire of high-rise apartment in the disaster area and calls to a person who asked for help in order to give out directives on the evacuation.

These scenarios as such are no problem except when there is congestion on the receiving side. In that case either the emergency attendant or the risk management office should be able to get in touch and establish the call.

In technical terms, the people like emergency attendants and disaster risk management office attendants are called authorised users and the ordinary people who need help are known as unauthorised users.

It should also be possible to make a small duration call between unauthorised users so people can check each others safety. This can be controlled by changing the permission of different access class for small durations so that people can trigger calls for small duration.

The study found that eMLPP (Enhanced Multi-Level Precedence and Pre-emption) that is already available since GSM days can resolve the problem of prioritisation in resource allocation. A new capability will be required to allow UEs with indications from the network to perform location registration and respond to a paging request even though it is under access class barring conditions to complete certain classes of calls or messages (e.g. calls from emergency personnel, …).

This new capability will be available probably when Release 9 is finalised in December this year.

As far as understanding this eMLPP is concerned, the following book has quite a lot of details on this topic. If you can get hold of it then do go through it.

Preferential Emergency Communications: From Telecommunications to the Internet (The Springer International Series in Engineering and Computer Science)

Here is the google books link for that.