Friday, 6 July 2007


Interesting development that happened last month at the 3GPP plenary meeting in Busan, Korea earlier this month, an agreement was reached on how to proceed with Common IMS to meet the needs of fixed, mobile, broadband and wireless users.

In cooperation with the European Telecommunications Standards Institute, the 3rd Generation Partnership Project (3GPP) has re-chartered a services group tasked with common ETSI-3GPP development of IP Multimedia Subsystem (IMS) Version 8.

Both standards bodies hailed the early June agreement, reached during a meeting in Busan, Korea, as an effective way to keep 3GPP IMS and ETSI Telecoms & Internet converged Services & Protocols for Advanced Networks (TISPAN) work.

Both IMS and TISPAN comprise next-generation network standards efforts designed to forge a higher signaling and control plane infrastructure layer to support delivery of content and applications to subscribers across any fixed or mobile network or device.
“ETSI TISPAN has taken the first steps in migrating fixed IMS requirements to 3GPP in a co-operation that will prevent fragmentation of IMS standards,” Dr. Walter Weigel, ETSI Director-General, said. “A Common IMS, developed in one place, is a big step forward and will bring enormous economies of scale and reductions in capital and operational costs.”

Common IMS developments will form part of 3GPP Release 8, which is expected to be functionally frozen by end 2007.

Over the next few months we must stabilize the Release 8 requirements and absorb the incoming Common IMS work,” Stephen Hayes, Ericsson Inc., 3GPP TSG-SA Chair Stephen Hayes of Ericsson Inc., said. “3GPP has a history of successfully meeting challenges and I have no doubt we will meet these challenges as well.”

Wednesday, 4 July 2007

AIPN Scenarios

AIPN or All-IP Network is being introduced part of 3GPP Release 7. TS 22.978 shows some scenarios where AIPN will play a big part

USE CASE 1 (see left in the daigram): Bob has his own Personal Area Network (PAN). While at home, this network is composed with the Home Area Network using WLAN, which in turn connects externally with a local hotspot service, which in turn connects to a cellular network. Bob's PAN, Bob’s Home-WLAN, the local hotspot service and the AIPN cellular access system are under different administrative domains. Still, if Bob moves outside coverage of his Home-WLAN, his PAN will communicate with the outside world via the local hotspot service. If he moves outside coverage from the hotspot service, his PAN will communicate with the outside world via the AIPN cellular access system.

USE CASE 2: The user is driving a car. While being under good radio coverage, he starts an IMS session with several media. The car goes through a tunnel where there is no radio coverage, and comes out of the tunnel into good radio coverage a minute later. Connections using disruption resilient transport protocols are automatically re-established and these protocols restore the communication to the point they were before the interruption.

USE CASE 3: Alice has a mobile device and Bob has a fixed one. Both devices have equal audio but different video capabilities in terms of screen size, number of colors and video codecs supported. Alice establishes a multimedia connection with audio and video components to Bob. The terminal capabilities are discovered and it is realized that Bob's terminal has better video capabilities than Alice. The terminal informs the network that it is unable to support new the new video codec and the AIPN then introduces a video transcoder in the path of the video media to adapt the video signal (stream, codec, format, etc) to the video capabilities and bit rates available on each side of the transcoder.

Enhanced Services should be possible with AIPN:

  • Support for advanced application services
  • Support for group communication services, e.g. voice group call, instant group messaging, and multicast delivery. In some cases, a group may include a large number of participants.
  • Support for integrated services, e.g. a service including a mixture of services among SMS/MMS/Instant Message, or a service including voice call/video call/voice mail.
  • Provision of seamless services (e.g. transparent to access systems, adaptable to terminal capabilities, etc) Users should be able to move transparently and seamlessly between access systems and to move communication sessions between terminals.
  • Support ubiquitous services (e.g. associations with huge number of sensors, RF tags, etc.) ... see right side of diagram above.
  • Improve disruption-prone situations when network connectivity is intermittent.

Disruption-free network connectivity may not be cost effective, or even feasible, in all cases (e.g. cell planning for full radio coverage for all services, disruption-free inter-access system handovers, disruption-free IP connectivity in all network links). An AIPN should consider solutions for making services as resilient to temporary lack of connectivity as possible.

Monday, 2 July 2007

Introduction to All-IP Network (AIPN)

The All-IP Network (AIPN) is an evolution of the 3GPP system to meet the increasing demands of the mobile telecommunications market. Primarily focused upon enhancements of packet switched technology, AIPN provides a continued evolution and optimisation of the system concept in order to provide a competitive edge in terms of both performance and cost. Moreover, it is important that developments of the 3GPP system are compliant with Internet protocols. The AIPN is not limited to consideration of only the transport protocol used within the 3GPP system but adheres to the general concept of a network based upon IP and associated technologies, able to accommodate a variety of different access systems. Although, it is possible to use a variety of different access systems to connect to the AIPN, the AIPN provides an advanced, integrated service set independent as far as possible from the access system used.

The high level objectives of introduction of the AIPN are to realise:

  • universal seamless access
  • improved user experience
  • reduction of cost (for AIPN operators)
  • flexibility of deployment.

There are also a number of motivations and drivers for the introduction of the AIPN which include but are not limited to:

  • diversification of mobile services
  • need to satisfy user experience of early adopters
  • anticipation of PS traffic to surpass CS
  • desire to encompass a variety of access systems
  • need for increased system efficiency and cost reduction (OPEX and CAPEX) and
  • advances of next generation radio access systems and broadband wireless IP-based networks.
The key aspects of the AIPN can be summarised as follows:
  • Support for a variety of different access systems
  • Common capabilities provided independent to the type of service provided with convergence to IP technology considered from the perspective of the system as a whole
  • High performance mobility management that provides end-user, terminal and session mobility
  • Ability to adapt and move sessions from one terminal to another
  • Ability to select the appropriate access system based on a range of criteria
  • Provision of advanced application services as well as seamless and ubiquitous services
  • Ability to efficiently handle and optimally route a variety of different types of IP traffic including user-to-user, user-to-group and ubiquitous service traffic models
  • High level of security and support for user privacy e.g. location privacy, identity privacy
  • Methods for ensuring QoS within and across AIPNs
  • Appropriate identification of terminals, subscriptions and users
  • Federation of identities across different service providers
Further Reading:
3GPP TS 22.258: Service Requirements for the All-IP Network (AIPN);
Stage 1

3GPP TR 22.978: All-IP Network (AIPN) feasibility study

Wireless and Mobile All-IP Core Networks and Services

Next Generation Mobile Systems: 3G & Beyond

Sunday, 1 July 2007

C-Mobile: 3GPP MBMS for systems beyond 3G

Came across the C-Mobile website, searching for some information and the site caught my eye.

The strategic objective of C-MOBILE is to foster the evolution of the mobile broadcast business by providing enhancements to the 3GPP MBMS for systems beyond 3G.

Having worked with MBMS for some time and having completed atleast 4 trainings, the topic definitely holds my interest.

C-MOBILE will help to understand how best to organise and schedule MBMS content from the BM-SC through the core network, radio access, to the end users. Since this is multimedia content, interactions with the 3GPP IP Multimedia Subsystem are expected and C-MOBILE will explicitly investigate how best MBMS can make use of capabilities provided by the IMS.

The current concept of group communication is narrow within Release 6 MBMS specification.
C-MOBILE will research, investigate and define ways to use multicast technology to support personalized services and in particular the concept of multicast content community where users also contribute to the multicast service.

Key market and business requirements for multicast-broadcast services will be identified to aid defining research directions, leading also to new business models involving the various players.

To that end it is critical to understand the needs of multicast-broadcast users, network operators, and content providers.

The project intends to make important contributions to the standardisation bodies and to prove experimentally or via system level simulations innovative concepts.

There are no high profile names with C-mobile yet but there is Qualcomm and 3 UK in the participants list.

Some documents of interest are available here.

Push-to-share over MBMS

During one of my MBMS trainings last month in Anritsu, i set everyone a task of defining a service based on MBMS. One of the services mentioned was Push to Talk (PTT) over MBMS.
Theoretically it should be possible to use MBMS for PTT. The voice in the UL is sent via a normal CS RAB. On the Downlink the data is Broadcast using MBMS. Since we would like the data to be sent to a particular set of users, it would be Multicasted rather than Broadcasted. Also this would mean that only the users in a particular Service Area will be able to receive this.
From operators point of view, Service Area should be big enough so that the user is seamlessly able to move a wide geographical area. At the same time it should not be too big because localised services (and adverts) can generate more revenue.
A bit of Googling and i came across some patents that are trying to do the same. Following is an extract from a patent Fresh Patents:
[0009] Use of a PoC application server together with a multimedia
broadcast/multicast service (MBMS) server for providing multicast transfer of
data in the downlink direction has been suggested. In the uplink direction PoC
typically uses Real Time Protocol (RTP) traffic unicast. In the uplink PoC
clients send speech data to the PoC application server, which then directs the
speech data packets either to the MBMS for the downlink leg to those
participants who receive the speech via multicast service or directly to those
recipients who prefer to receive via unicast directly from the PoC server. Use
of multicast in downlink direction improves the spectral efficiency in the case
of group communications with great number of participants. In addition, without
multicast it may not be possible to support large group sizes, if the
participants are located geographically in the close proximity.
Another was a patent on free patents:

0032] Herein, the MBMS service refers to a service for transmitting the same
multimedia data to a plurality of recipients through a wireless network. In this
case, the recipients share one radio channel, thereby saving radio transmission
resources. For example, the MBMS service includes a stock information service,
sport broadcast service, Push-to-Talk (PTT) service, and the like.
In fact C-Mobile is working on something similar. One of their documents highlight the limitations of the current MBMS architecture and suggests how we can improve the architecture in future for B3G Architecture.
My personal feeling is that till the Architecture is eveolved enough, PTT may not be very practical over MBMS but we should be able to use Push-to-share over MBMS. Some interesting short video clip or Breaking News Clip or maybe personal Valentine messages, etc can be shared using MBMS. It now needs to be seen if some operator picks on this idea and how soon.

Thursday, 28 June 2007

OFDM and OFDMA: The Difference

I was curious as to why IEEE 802.16d (fixed service) uses Orthogonal Frequency Division Multiplexing (OFDM). IEEE 802.16e (mobile) uses Orthogonal Frequency Division Multiple Access (OFDMA). So, what’s the difference between the two, and why is there a difference?

Lets first look at FDM:

In FDM system, signals from multiple transmitters are transmitted simultaneously (at the same time slot) over multiple frequencies. Each frequency range (sub-carrier) is modulated separately by different data stream and a spacing (guard band) is placed between sub-carriers to avoid signal overlap.

OFDM is sometimes referred to as discrete multi-tone modulation because, instead of a single carrier being modulated, a large number of evenly spaced subcarriers are modulated using some m-ary of QAM. This is a spread-spectrum technique that increases the efficiency of data communications by increasing data throughput because there are more carriers to modulate. In addition, problems with multi-path signal cancellation and spectral interference are greatly reduced by selectively modulating the “clear” carriers or ignoring carriers with high bit-rate errors.
Like FDM, OFDM also uses multiple sub-carriers but the sub-carriers are closely spaced to each other without causing interference, removing guard bands between adjacent sub-carriers. This is possible because the frequencies (sub-carriers) are orthogonal, meaning the peak of one sub-carrier coincides with the null of an adjacent sub-carrier.

In an OFDM system, a very high rate data stream is divided into multiple parallel low rate data streams. Each smaller data stream is then mapped to individual data sub-carrier and modulated using some sorts of PSK (Phase Shift Keying) or QAM (Quadrature Amplitude Modulation). i.e. BPSK, QPSK, 16-QAM, 64-QAM.

OFDM needs less bandwidth than FDM to carry the same amount of information which translates to higher spectral efficiency. Besides a high spectral efficiency, an OFDM system such as WiMAX is more resilient in NLOS environment. It can efficiently overcome interference and frequency-selective fading caused by multipath because equalizing is done on a subset of sub-carriers instead of a single broader carrier. The effect of ISI (Inter Symbol Interference) is suppressed by virtue of a longer symbol period of the parallel OFDM sub-carriers than a single carrier system and the use of a cyclic prefix (CP).
The OFDM spread-spectrum scheme is used for many broadly used applications, including digital TV broadcasting in Australia, Japan and Europe; digital audio broadcasting in Europe; Asynchronous Digital Subscriber Line (ADSL) modems and wireless networking worldwide (IEEE 802.11a/g).
Like OFDM, OFDMA employs multiple closely spaced sub-carriers, but the sub-carriers are divided into groups of sub-carriers. Each group is named a sub-channel. The sub-carriers that form a sub-channel need not be adjacent. In the downlink, a sub-channel may be intended for different receivers. In the uplink, a transmitter may be assigned one or more sub-channels.
Subchannelization defines sub-channels that can be allocated to subscriber stations (SSs) depending on their channel conditions and data requirements. Using subchannelization, within the same time slot a Mobile WiMAX Base Station (BS) can allocate more transmit power to user devices (SSs) with lower SNR (Signal-to-Noise Ratio), and less power to user devices with higher SNR. Subchannelization also enables the BS to allocate higher power to sub-channels assigned to indoor SSs resulting in better in-building coverage.

Subchannelization in the uplink can save a user device transmit power because it can concentrate power only on certain sub-channel(s) allocated to it. This power-saving feature is particularly useful for battery-powered user devices, the likely case in Mobile WiMAX.

The WiMAX forum established that, initially, OFDM-256 will be used for fixed-service 802.16d (2004). It is referred to as the OFDM 256 FFT Mode, which means there are 256 subcarriers available for use in a single channel. Multiple access on one channel is accomplished using TDMA. Alternatively, FDMA may be used.

On the other hand, OFDMA 128/512/1024/2048 FFT Modes have been proposed for IEEE 802.16e (mobile service). OFDMA 1024 FFT matches that of Korea’s WiBRO. OFDM 256 also is supported for compatibility with IEEE 802.16d (fixed, 2004).

3G in 900MHz band can make 3G a winner

The widespread deployment of 3G networks in the 900MHz GSM spectrum band, as well as the 2100MHz band, could enable an additional 300 million people across Asia, Europe and Africa to enjoy mobile broadband services by 2012, according to a study by the analyst and consulting company Ovum for the GSMA.
Note: HSPA is already being deployed at 900MHz in Finland and trials are underway in a number of other countries, such as France and the Isle of Man. More about this is available here.
In 900MHz, the greater range of radio waves in the lower spectrum band and their ability to provide better coverage in buildings would enable operators to achieve much broader 3G coverage, particularly in rural areas. The study shows that a 3G network in the 900MHz band would achieve up to 40% greater coverage than a 3G network in the 2100MHz band for the same capital expenditure.
The cost-effectiveness of 3G at 900MHz would be of particular significance in developing countries, many of which are looking to HSPA, an evolution of the leading 3G technology, to provide high-speed Internet access in the many regions that lack fixed-line infrastructure. However, Ovum cautions that the level of success of 3G in the 900MHz band will depend on multiple countries making this spectrum band available in a harmonised way, so that equipment manufacturers have a large market to target and can quickly achieve economies of scale, particularly for handsets.
Ovum envisages that operators would use 900MHz to provide widespread 3G coverage, supplemented by 3G at 2100MHz in urban ‘hot-spots’ that need more capacity. The extensive use of both the 900MHz and the 2100MHz bands for 3G in Asia–Pacific countries could lead to 450 million people in the region using 3G by 2012, if all operators chose to deploy 3G and the majority of investment goes into 3G at 900MHz. If 3G were restricted to 2100MHz alone, Ovum forecasts there will be just 200 million people using 3G in the region by 2012.
In light of these findings, the GSMA urges regulators, together with vendors, to plan together for the coordinated refarming of 900/1800MHz spectrum, which is widely used for GSM in Europe, Asia and Africa, and for the availability of compatible and affordable handsets. Such global planning will give investors the confidence to fund the development of 3G/HSPA at 900MHz and 1800MHz as well. There should be no differentiation between the different GSM bands (900/1800/1900) to avoid any distortion of competition among GSM operators. The same benefits would also be achieved by refarming 850MHz spectrum (widely used in US and Latin America).
According to the Inquirer, the GSMA may have fallen into a trap. China has its own flavour of 3G – called TD-SCDMA. One of the benefits of this standard – compared to W-CDMA which the GSMA promotes – is that it shares infrastructure costs with existing GSM equipment. Naturally providing cost savings. So while the GSMA is admitting that standard W-CDMA at 2100 MHz is too expensive for developing economies, China can quite reasonably say, "We know. That's why we've stuck with TD-SCDMA.
A bit of an own goal really.

Tuesday, 26 June 2007

OMA seeks to ease mobile TV pain

The Open Mobile Alliance's recently-unveiled BCAST Enabler specification is designed to create a 'write once, run anywhere' environment' for broadcasters and other content providers. The spec - if widely adopted - could have significant implications for the concept of mobile TV 'roaming'.
In theory, it means broadcasters will be able to deploy their programming across the whole gamut of broadcast mobile TV platforms - DVB-H, DVB-SH, DMB, DAB-IP, ATSC-M/H etc - with little or no tweaking.
Because it works with any IP-based content delivery technology BCAST Enabler can also be used for the delivery of programming across cellular systems like 3GPP MBMS, 3GPP2 BCMCS and mobile unicast streaming systems, such as 3G streaming.

What benefits will OMA BCAST offer broadcasters and broadcast network operators?
• The specification enables broadcast-only mode for delivering services. It also allows broadcast-only terminals and free-to-air content with service and content protection capability.

• The specification is agnostic to access network meaning that the same service offering can be delivered over broadcast channel, interaction channel or both. Being agnostic to underlying architecture allows integration of the broadcast offering with operators or independent delivery over the interaction channel, which is controlled by broadcaster.

• Service interactivity is well specified and caters for broad range of services including interactive and direct feedback from viewers. Also, the service interactivity is not bound to the cellular channel – WLAN or a similar network can also be used. The use of the interaction channel allows personalization of services and service guides.

• The Service Guide enables the broadcaster to associate broadcast
programming with on-demand content. In addition, it supports both broadcast and on-demand delivery of the Service Guide itself.

What benefits will OMA BCAST offer terminal manufacturers?

• The Mobile TV Enabler specifies features for a common TV & video service layer that are currently not addressed by other specifications but still needed to ensure interoperability for large-scale terminal availability.

• Enables economies of scale by leveraging same technologies for both
broadcast and interactive channels. This means vendors can build an
economically viable terminal base that can be used by operators/carriers or broadcasters or jointly by both.

Sunday, 24 June 2007

Certified Wireless USB's and Cablefree USB

While doing some background sstudy of Wireless USB i came acrosss interesting information. Apparently there are two different Wireless USB standards that are being developed and they are not compatible with each other. More information aas follows:

Wireless USB (also known as Cablefree USB)

* Supported by UWB forum (pioneered by Freescale semiconductor)

* Uses DS-UWB (direct sequence)

* It mimics USB 2.0 in its interfaces to host and peripheral devices, handling the wireless issues within device adapters.

* This approach of retaining the USB 2.0 protocol means that developers can quickly offer products that users can simply plug in without making any system changes.

* Existing USB drivers will work

* The current Freescale UWB chipset operates at 114Mbps with a likely throughput of 50Mbps

Certified Wireless USB

* Supported by WiMedia alliance and USB-IF (USB Implementers Forum)


* Certified Wireless USB employs a new communications protocol, similar but not identical to USB, to address the wireless issues.

* The Certified Wireless approach, on the other hand, required the definition of a new specification. The initial specification, which its developers released in May 2005, received a supplement defining the association's methods in March 2006. The specifications are now under the control of the USB-IF.

* Will need new software and USB drivers

* They operate at 480Mbps like USB 2.0 with probably similar throughput (peak 320Mbps)

Friday, 22 June 2007

2.5 Billion GSM Subscribers Worldwide

Bellevue, WA, June 05, 2007 -
Today, 3G Americas reports that the number of GSM mobile wireless subscribers worldwide has reached 2.5 billion, a stunning 400% increase in GSM subscribers from only six years ago, according to the estimates of Informa's World Cellular Information Service. Every day, there are more than one million new additions to the GSM family of technology users receiving service from one of 700 commercial GSM networks across 218 countries and territories around the world.

“It’s unprecedented for almost any global industry to achieve the growth and success demonstrated by the GSM family of technologies, with an estimated 2.5 billion global customers today,” stated Chris Pearson, President of 3G Americas. “This level of wireless technology growth exceeds that of almost all other lifestyle-changing innovations.”
Looking back, it was almost one hundred years ago when the first so-called "mobile" phone call was made by Lars Ericsson in 1910— although not wireless, as Ericsson attached wires to a telephone pole terminal to make his call while on the road. 2007 marks the 60th anniversary of AT&T and Bell Laboratories' 1947 invention of the cellular phone. Today, it is estimated that more than 37% of the world's 6.6 billion people (US Census Bureau) use GSM technology.

GSM subscribers, including nearly 130 million UMTS/HSDPA subscriptions, currently comprise nearly 85% of the global mobile wireless market. GSM became the dominant Latin American mobile wireless technology in less than a decade since its launch in the region in 1998, acquiring 2 million subscribers by the year 2000, and 200 million by end of year 2006. The GSM family now serves 331 million customers in all the Americas as of 1Q 2007, and is available in every single country. This market leadership is due to the numerous technical and economic benefits of the GSM family of technologies for both operators and their customers.

GSM technologies, including GPRS, EDGE and UMTS/HSPA, offer overwhelming advantages in terms of global scope, scale, international roaming and service that are still unmatched by other mobile wireless technologies. As of May 2007, there are 169 UMTS operators in service across 71 countries, and 117 of those operators in 59 countries have deployed an enhanced version of UMTS called HSDPA. Additionally, nearly all UMTS/HSDPA devices manufactured today include the EDGE technology as the compatible fallback technology, allowing for global roaming and delivery of high-speed wireless data services.
HSPA (HSDPA/HSUPA) technology is poised to be the leading mobile broadband technology for the rest of the decade, outpacing alternative mobile broadband technologies by leveraging on the current installed base of the GSM family of technologies and providing the most efficient solution. It is expected that almost all GSM/EDGE operators will someday migrate to HSPA technology.

Pearson continued, “While other technologies are grabbing attention, HSPA is being rolled out around the world, separating future promise from that which is available today. Building upon the enormous foundation of customers and commercial deployment of GSM, and the broad research and development by vendors, HSPA will continue in its mobile broadband leadership position for years to come.”

For white papers, statistics and more information on the GSM family of technologies, visit

About 3G Americas: Unifying the Americas through Wireless Technology
The mission of 3G Americas is to promote and facilitate the seamless deployment throughout the Americas of GSM and its evolution to 3G and beyond. The organization fully supports the Third Generation (3G) technology migration strategy to EDGE and UMTS/HSPA adopted by many operators in the Americas. The GSM family of technologies accounts for 85% of wireless mobile customers worldwide. 3G Americas is headquartered in Bellevue, WA with an office for Latin America and the Caribbean in Dallas, TX. For more information, visit our website at

About Informa Telecoms & Media
Informa Telecoms & Media provides business intelligence and strategic services to the global telecoms and media markets. All of our products and services - from news, trend analysis and forecasting to industry data, face-to-face events and training - are driven by our deep understanding of the markets we serve and by our goal to help our clients make better business decisions.