Saturday 29 September 2007

WiMAX World Highlights

WiMAX is strating to be rolled out and this will definitely give it an advantage over LTE/UMB.

Motorola demoed its new WiMAX 802.16e mobile handoffs across a Sprint brand Xohm prototype network on a boat cruising downtown Chicago’s skyscraper-canyoned mid-town river. Not only was it good clean fun for the attendant pundits, punters and analysts, it was an impressive real-life demonstration of an important nascent technology that they could just as easily, and less expensively have unveiled in the controlled environs of the conference hall – boring as hell like usual – but they did not. Motorola and gang literally went the extra mile by also mounting the new WiMAX exhibition on a rolling Chicago public transit coach caroming about the city’s elevated metro tracks at 50 miles per hour, all the while delivering pretty seamless mobile apps like web browsing, VoIP, video streaming and Mobile TV.

Elsewhere, NextWave Broadband and Huawei Technologies also this week announced the interoperability testing of NextWave’s 802.16e mobile WiMAX chipsets and Huawei’s WiMAX infrastructure equipment in San Diego.

Telsima announced that the company’s Indian WiMAX Rollout was awarded the Best of WiMAX World USA 2007 Award for its StarMAX™ Solution in the WiMAX World Digital Cities Deployment category by the xchange magazine. The annual awards were presented in a late evening award ceremony on September 26 at the WiMAX World Conference held at Chicago on Sept. 25-27, and recognized leaders in the development and deployment of WiMAX technologies. In its second year, the awards received more than 80 submissions and Telsima pipped at the post several strong contenders to establish its leadership.

Telsima has established leadership position in WiMAX by enabling multi-city rollouts for Tier 1 operators, including, Reliance Communications and Tata-VSNL in India. The WiMAX rollouts, with thousands of base station sectors already shipped, support several advanced functionalities, like, MIMO & STC Antenna Diversity in support of NLOS deployments. The equipment installed in rollouts covers WiMAX Forum Certified™ Telsima BS StarMAX 4120, 6100 and 6400 and SS StarMAX 2140 and 2150.

Nortel set up one of the biggest booths at WiMax World on the show floor, and announced that it is working with the Choctaw Electric Cooperative and Pine Cellular to bring WiMax to southeastern Oklahoma and other rural areas where it is not economically feasible to build a wired network.

Another category of devices under development are ultra-mobile PCs, or mobile Internet devices, which are about the size of a VHS tape and function somewhere between a laptop and a mobile phone. Samsung displayed a "butterfly" device that has three folding sections, including two that form a full keyboard used with a small screen. Nokia has an ultra-mobile device expected to launch next year with Intel technology inside. It was in the dashboard of a Mini Cooper as an entertainment center.

Meanwhile the Koreans revealed world's first mobile WiMAX gaming device. Called the G100 and developed by Posbro, a subsidiary of Posdata (itself a subsidary of huge Korea steel maker Posco), it's just been revealed at the WiMAX World USA 2007 exhibition in Chicago.In terms of hardware specs, the G100 features a widescreen four-inch touchscreen that slides up to reveal four buttons which act as a D-pad, four face buttons and a mobile-style nub. There are also two shoulder buttons.As for network technology, the G100 supports mobile WiMAX – itself a cell phone-style high-speed technology equivalent to 3G and 4G mobile networks – as well as old fashioned Wi-Fi and Bluetooth. This, Posbro says, will enable users to select the most appropriate network to make an internet connection.

Finally, Clearwire had a minimal presence. It didn't have a booth or splashy banners hung from the ceiling. It didn't host a cruise on the Chicago River to show off its service. But the conference did pause Thursday to hear a progress report from the Kirkland-based company.

Clearwire, founded by wireless entrepreneur Craig McCaw, has been in business four years and serves more than 40 markets in the U.S. and a handful of cities in Europe.

The company offers a precursor to WiMax technology. Users receive a modem — about the size of a hardback book — that can be used anywhere in a service territory, though not on the go, such as in a moving vehicle.

Clearwire's progress differs from the rest of the industry, which is waiting to build networks based on true mobile WiMax technology, expected to be available early next year. "The difference with Clearwire and other folks in the room is that while others are planning, we are in service today," Richardson said.

In his speech, Richardson offered a rare glimpse into operations of a company that usually prefers to stay out of the spotlight and say little. Here are a few points worth noting, gathered from his presentation and a one-on-one interview:

  • Clearwire has about 300,000 subscribers. In August, 41 percent of its customers migrated from cable Internet access and 29 percent from DSL.
  • The combined total is about 10 percent more than in the first quarter, when 59 percent of customers moved from DSL or cable.
  • Clearwire is starting slowly to roll out mobile WiMax — which can be used on the go — into new markets, including Portland.
  • Deployment of true mobile WiMax is going well in Portland, Richardson said. In April, Clearwire completed the first phase, involving 15 square miles. It's now focused on a beta network covering 145 square miles.
  • In 2008, it expects to see laptops with embedded chipsets, as well as WiMax-enabled handsets.
  • As for a WiMax business model, he said that will likely evolve as networks become available. "I believe the future is driven by the types of things you do at home today and want to do on the go, but we have to provide the connectivity to enable the business model."
  • Richardson said a lot of the complexity in the business will be in the back end of Clearwire's network, where it handles billing. As a result, it bought IntraISP, of St. Louis, which will be a subsidiary and be able to sell billing solutions to other companies.

Wednesday 26 September 2007

Verizon defects to LTE camp

3GPP is celebrating after Verizon Wireless announced that it would be using 3GPP backed LTE as its next generation wireless technology of choice. Of course the decision was influenced by its sister company Vodafone. Verizon Wireless is currently using CDMA2000 EV-DO Rev 0 and Rev A in its wireless network in the US, which means that Verizon's natural next technological step on the way to 4G should have been the adoption of UMB. However, this decision is not as simple as it seems, as shown by Verizon Wireless' selection of LTE over its CDMA counterpart.

Just a few months removed from rumors that Vodafone would offload its stake in Verizon Wireless altogether, the two networks have announced that they'll share a common selection for their fourth-generation data networks: Long-Term Evolution. Endorsed by the 3GPP as the official way to burn wireless rubber in the next few years, LTE is a progression of GSM's UMTS platform, making it an ironic choice for CDMA stalwart Verizon and a huge blow for the CDMA Development Group's competing UMB standard. It seems that the unusual move was influenced by the fact that the sister networks -- two of the world's largest -- should probably enjoy some semblance of technological synergy if they're going to carry on their blissful matrimony for the foreseeable future, with Verizon CEO Ivan Seidenberg saying the company has been looking for "stability" in the relationship. Whatever the case, don't throw away that brand spanking new VX8550 or anything rash like that -- the companies aren't looking to roll anything out for another three or four years.

According to Ovum report:
This announcement is bad news for the UMB camp and its main backer, Qualcomm, as there is still no major CDMA operator that has committed to rolling out UMB technology. For example, the other largest CDMA operator in the US, Sprint Nextel, which also operates Rev 0 and Rev A CDMA networks nationwide embraced the mobile WiMAX technology for its next generation wireless network. At the same time, in Japan, KDDI which is one of the most significant CDMA operators worldwide has just announced the creation of a joint-venture to bid for a 2.5GHz licence in order to deploy a mobile WiMAX network.

Even if UMB is often marketed as benefiting from a time-to-market advantage compared to its 3GPP rival, UMB's future is not looking as bright as some vendors may have hoped for.

Verizon Wireless' move is significant for LTE, as it is a win in CDMA's birthplace and consequently strengthens its position as a potential alternative to UMB for other CDMA operators worldwide. One of the key selection criteria for any technology is its capability to generate economies of scale. Compared to UMB, LTE was already benefiting from an advantage in this domain as 3GPP technologies enjoy wider adoption worldwide and this, in addition to the fact that there's no strong commitment from major operators behind UMB, means that UMB's appeal is considerably weakened.

For Vodafone and Verizon Wireless, the decision to adopt a common technology for next generation wireless networks means that the companies have a common long-term view and therefore implies their relationship is long term. 'This LTE thing plays out probably over five to six years', said Verizon CEO Ivan Seidenberg, thus reinforcing Vodafone's insistence that it is not looking to sell its equity investment in the US operator. Using a common platform for next generation wireless services will also fix the current roaming issues due to system incompatibility between CDMA and GSM that Verizon or Vodafone subscribers are experiencing today when travelling.

This announcement also comes as clarification from Vodafone, by reiterating Vodafone's commitment to LTE as its mainstream technology for next generation wireless networks - a position WiMAX believers challenged after Vodafone joined the WiMAX Forum and Arun Sarin's announcements at a couple of industry events. However, if LTE's backers want to keep the lead at Vodafone, they would be particularly well advised to take into account Sarin's comments regarding LTE time-to-market issues.

More on LTE at 3G4G website.

Sunday 23 September 2007

Random Statistics

While searching for some figures and numbers, came across loads of stats which i am posting hre for information only

  • Skype currently having 220 million subscribers, they are already the third largest telecoms operator in the world according to subscriber count. They deliver 7 billion minutes of telecoms traffic (between Skype users) and 1.3 billion Skype out minutes. Skype has 4% of all international and long distance traffic worldwide
  • Three UK delivered 14.2 million videos via SeeMeTV in 12 months, and also sold 6 million games in the past year. (Aug 2007)
  • My Faves in USA, T-Mobile's new user interface/portal and digital community has 3 million subscribers in the USA (Aug 07)
  • 3G penetration rates in Italy are already at 29%, Spain and UK are at about 18%. Even the USA is getting well along into 3G, with 13% having migrated to 3G. Between 15% and 29% of phone owners in these countries use picture messaging. Between 3% and 13% consume news on mobile phones. But so far only between 1.9% and 3.3% of phone owners consume mobile social networking services.(M:Metrics Aug 07)
  • Admob has served 5 BILLION mobile ads in past 6 months (Sep 07)
  • USA mobile phones users who consume VAS services (excluding SMS) 27.5% (IDC December 2006)
  • UK phone users who access 11% email; 14% music; 15% ringing tones; 19% internet; 26% gaming; 35% MMS, 85% SMS. (Telephia January 2007)
  • Japan 32% of phone users subscriber to games (Wireless World Forum 2006)
  • UK (kids age 6-14) download 17% ringing tones; pictures 22%; games 24%; music 25%; and 29% access internet (Intuitive Media Dec 2006)
  • USA 19% of internet users access by mobile; UK: 24% of internet users access by mobile (ComScore Metrics Oct 2006)
  • USA 40% of mobile phone users have used mobile web services; 10% do so regularly (TNS March)
  • Measured in revenues, globally, non-SMS revenues on mobile are worth 31.3 Billion dollars. Out of that, "browsing" delivers 1.9 billion dollars. It is only the 6th largest category according to Informa. Music is worth 8.8 B, infotainment 6.4 B, etc.
  • Of Korea's 33m Internet users, 21.3m were fixed-only, 11.0m were fixed+mobile, and 0.5m were mobile-only (Feb 06)
  • In CHina, 137m Internet users, of which 17m access via mobile, and 104m via broadband (Dec 06)
  • while 29% of European Internet users regularly access the Internet from their mobile phones, only 19% of US users were accessing the web via their mobile devices. The highest mobile Web penetration was in Germany, Italy and the UK (at 34% each), followed by France and Spain, and the US. (eMarketer, Oct 06)
  • 5.7m people in the UK used a mobile device to access the internet in January 2007, 19% of the 30m people who accessed the web from a PC. (comScore and Telephia)
  • In Japan in June 2007, almost as many people accessed the internet via a mobile device there as through a work or home PC (the exact figures are 53.6 million and 53.7 million respectively). The same report reveals that Japanese mobile users spend on average 8.1 hours a month surfing on their phones.
  • Mobile statistics gatherers M:Metrics has just released its latest survey of mobile internet use. And lo and behold, it has found that in both Europe and America, mobile men like to use their handsets to read about… Sports! Meanwhile, M:Metrics found that American ladies’ most popular mobile internet topic was the weather, while European women were more interested in news and entertainment gossip. Vaguely interestingly, while the total numbers of mobile net users in Europe and the US were fairly similar (18 million versus 22 million), the number of American females browsing the net on their mobiles was, proportionally, much higher. The most popular topic among US women (the weather) reached 3.5% of the audience, while in Europe the top item, the news, reached just 1.6%.

Saturday 22 September 2007

Google: New Operator on the Bloc

The mobile phone companies Vodafone and O2 will be forced to hand over large chunks of prime spectrum to their rivals as part of a plan unveiled by the telecoms regulator Ofcom to stimulate usage of wireless frequencies for mobile broadband services.

With new spectrum being available and no restriction on the technology to use Google is considering a move into the UK wireless market. Google is already planning to bid more than $4.6bn (£2.3bn) on spectrum in the US when it comes up for sale early next year and is rumoured to be working on its own mobile phone, nicknamed the Gphone, and a mobile payments service called GPay.

All four "legacy" operators have been lobbying for the regulator to remove restrictions on what services they can run over their old networks. They were not expecting Ofcom to propose a full-scale re-auction of part of the existing spectrum.

Orange, T-Mobile and 3 will be allowed to bid for the old Vodafone and O2 spectrum, but it is unclear whether they need the extra capacity. Vodafone has a network-sharing deal with Orange that should cover both companies' needs when the new spectrum is released in 2010, and T-Mobile and 3 are exploring a similar arrangement.

It was unclear last night whether the removal of a third of its 2G network capacity would harm O2, but the move is certainly a blow as that is the spectrum over which the iPhone will operate. The mobile phone company, owned by Spain's Telefonica, clinched the high-profile iPhone deal this week, seeing off competition from Orange, T-Mobile and Vodafone.

Asian WiMAX Deployments to Threaten 3G Carriers

A number of Asian countries have resolved in recent months to adopt and promote WiMAX, a super high-speed wireless broadband technology which some analysts believe could ultimately threaten existing 3G wireless providers.

With its impressive bandwidth and range, WiMAX has the potential to cover anything from a bustling city to a remote village, and could be useful in both developed markets like South Korea and emerging ones like Vietnam.

The island nation of Taiwan is the latest proponent of WiMAX technology, granting six spectrum licenses in the past months, and pressuring the respective carriers to have their networks up and running within the next 18 months.

Analysts expect WiMAX equipment makers, such as Gemtek Technology Co Ltd., D-Link, ZyXEL Communication Corp., and Accton Technology Corp. to experience significant revenue growth in the coming quarters. Cell phone manufacturers like Samsung and LG are also likely to experience growth, as they begin to release WiMAX-enabled handsets and other devices.

“A key reason (to build WiMAX) is to drive the manufacturing industry for equipment vendors, and to create and nurture this ecosystem quickly,” commented Bill Rojas, the director of telecom research at International Data Corp (IDC).
Meanwhile in India, Equipment suppliers and operators are readying plans for the commercial rollout of WiMax broadband services in India though the Centre continues to dither on the broadband policy.

Said Protip Ghosh, vice-president, sales and marketing, Telsima Corp, which develops and provides WiMAX-based Broadband Wireless Access (BWA) and mobility solutions: “Though the government has set a target of 20 million by 2010, wire line will be able to cater to only five million and the rest will have to be met by wireless technologies such as WiMax.”

In fact, the technology is already being deployed by telecoms for hooking up their backhaul connectivity (between telecom towers) while widespread testing is on for commercial rollouts later.

BSNL, Reliance Telecommunications, VSNL, Bharti Televentures, Aircel, Sify, to name just a few, have already rolled out limited WiMax networks. Others like Tata Teleservices are testing networks at various places.

In fact, the biggest event being watched is the BSNL tender for 10,000 WiMax base stations slated to open sometime soon which could open the floodgates.

Telsima is looking to rollout a massive 10,000 WiMAX base stations and 1,00,000 WiMAX subscriber stations this year, most of them in India, according to Ghosh. Much will depend on how soon clarity on the broadband policy can be achieved by the Centre.

Interestingly, Telsima is already a supplier to VSNL and Reliance while Alcatel is currently in talks with the former to help in the commercial rollout of the technology.

“We are proud to be the first company to launch WiMax-based services in India,” Vinod Kumar, president (global data & mobility solutions), VSNL, told DNA Money. VSNL will extend its WiMax network to about 120 cities across India for enterprise customers and in five cities for retail customers by the end of the current financial year.

BSNL, which has undertaken pilots at 14 locations, is looking to roll out a WiMax network across 1,000 cities in the country.

In October 2006, Chennai-based mobile operator Aircel launched its broadband wireless access on WiMax and by December 2007, it will cover 44 cities.

An interesting thing to the whole broadband play will be the impending showdown between the WiMax players and the 3G lobby which, too, maintains that the WCDMA/HSPA standard is the best for broadband services for a country like India. “In our reckoning, WiMax will have only 5-10 per cent of the market,” said P Balaji, vice- president, marketing and strategy, Ericsson India, which is aggressively pushing the WCDMA technology.

In fact, given that choices have already been made in some 150 odd markets, HSPA will command a 75-80 per cent of the broadband market down in India, he said. However, given that Ericsson does not push WiMax technologies, one could perhaps take the opinion with a pinch of salt.

However, with less focus on mobility and powerful players like Intel aligned on its side, the WiMax lobby could emerge the winner in the long run.

Thursday 20 September 2007

FMC just a Hype?

According to Yankee group report, FMC is just a hype and its now fading.
Yankee Group revealed that fixed-mobile convergence (FMC) has strong potential to shake up the communications market for enterprise voice and mobility, but focus must shift from cost-savings to productivity in order for adoption to take-off. Today, FMC is sold with a focus on reducing cost for the enterprise, but with the subtext of productivity benefits for the end user. A consequence of this feature-focused approach is that FMC will not be the growth driver many carriers expect. Instead, it will be a necessary feature in carrier portfolios.
According to the recently published Yankee Group Note, Productivity Is the Prettier Face of FMC, enterprise adoption of FMC remains low. According to the Yankee Group Anywhere Enterprise—Large: 2007 European Fixed-Mobile Convergence Survey, only 2% of enterprises have deployed FMC. This number is even lower in the US and Canada. Competition from alternative mobility initiatives, technological immaturity and reduced priority placed on voice communications by IT decision-makers have contributed to this perception and low adoption rate. In addition, 29% of IT decision-makers surveyed in the Yankee Group Anywhere Enterprise—Large: 2007 US Fixed-Mobile Convergence Survey consider the technology nice to have, but not a critical application on their IT/networking road map. When combined with an adoption rate of less than 2%, this statistic does not bode well for FMC as it is currently configured and marketed.

"The FMC hype was a bit premature, but the day is not far off when FMC will play a major role in the way many people work," said Brian Kotlyar, research associate in Yankee Group's Enterprise Research group. "Integrating voice into mobile applications will be the new frontier for FMC. This will enable true differentiation between the FMC offerings of today that revolve exclusively around voice and the FMC applications of tomorrow that will enrich mobile data and increase Anywhere Enterprise™ productivity."
According to Telecommunications online (worth reading), During its short lifespan fixed-mobile convergence has gone from the greatest idea since bread was sliced to overhyped nonsense that will never happen. Along the way, it has still managed to maintain a small degree of respectability and potential.

From a report by MCF Corporation:

As deployment of 3G networks continues to grow, applications built for mobile entertainment should become more ubiquitous. According to Juniper Research, the value of the mobile entertainment market, including music, games, TV, sports and infotainment, gambling and adult content, could increase to nearly $77 billion by 2011 from $17.3 billion in 2006. Included in this forecast is the 50.2% CAGR of the mobile game
market by 2009 (to $10.9 billion from $3.1 billion in 2006). While one could argue the potential size of the mobile entertainment market, we believe that the transition to data has begun in an effort to reduce churn rates, preserve ARPU, and extend carrier brands.

The following highlights a few of the drivers:

Mobile entertainment and content. As deployment of 3G networks continues to grow, applications built for mobile entertainment should become more ubiquitous. According to Juniper Research, the value of the mobile entertainment market, including music, games, TV, sports and infotainment, gambling and adult content, could increase to nearly $77 billion by 2011 from $17.3 billion in 2006. Included in this forecast is the 50.2% CAGR of the mobile game market by 2009 (to $10.9 billion from $3.1 billion in 2006). While one could argue the potential size of the mobile entertainment market, we believe that the transition to data has begun in an effort to reduce churn rates, preserve ARPU, and extend carrier brands.

Location-based services (LBS): LBS is quickly emerging as a benchmark for service differentiation among mobile operators. According to ABI Research, GPS penetration in handsets could reach 1 billion by 2010 while Berg Insight projects 83% LBS growth in Europe, reaching a €5 billion market by 2010. We continue to expect LBS to be utilized for navigation, management/ tracking of assets, information (for example, mobile yellow pages) and emergency services. We are initially focusing on companies that offer machine-to-machine (M2M) applications which allow enterprises and consumers the ability to monitor and manage many types of assets (industrial vehicles, rental car fleets, real estate) in an effort to reduce costs and more efficiently operate.

Converged mobile devices, applications and services: According to IDC, the worldwide market for converged mobile devices increased 42% during 2006, reaching 80.5 million units, and is expected to cumulatively reach more than 1 billion units by 2011. Growth in shipments is primarily due to a greater selection of devices from which to choose and lower price points as mobile carriers look to differentiate their services. Many of these devices offer multiple features such as embedded cameras, MP3 players, GPS capability, and expended memory slots which allow subscribers the ability to carry only one device. We view the introduction of devices such as the iPhone as driving wireless data usage.

At the end of 1Q07, there were 2.8 billion wireless subscribers worldwide,
of which approximately 6%, or 172 million, were 3G subscribers. The 24% CAGR of total subscribers during the past four years has been driven by the rapid deployment of networks, availability and affordability of handsets, along with the introduction of new 3G services. We estimate 3G subscribers will grow at a 55% CAGR through 2010, reaching 652 million (approximately 14%) total estimated subscribers. We believe that wireless technology allows enterprises to become more efficient operators due to the lower costs to deploy and operate, comparable capacity to wireline solutions, increased functionality and productivity, and ability to track personnel and assets.

The chart above illustrates how data ARPU has stabilized total ARPU for AT&T Wireless/Cingular ($48-50 range), which has more than 62 million subscribers. AT&T currently reports approximately 33 million data customers (up more than 30% Y/Y) the growth of which has begun to reflect wider usage of its new 3G UMTS/HSDPA network (current coverage in 165 cities and is on schedule to cover virtually all of the top 100 U.S. markets by the end of 2007). The trend of wireless data
growth offsetting decreases in total ARPU is clearly evident below and is occurring throughout the industry.

Monday 17 September 2007

MBMS but no Multicast

From the discussions going on in the industry, it seems that MBMS is being implemented by everyone but no one is concentrating on Multicast. This means we should now change MBMS to MBS but ofcourse it doesnt sound as good ;).

In the discussions going in RAN5 on the testing side, Nokia, Qualcomm and Ericsson has indicated that they are not interested in Multicast at the meoment (and probably for long time) and Mobile TV using MBMS will only be using Broadcast services.

The main reason for Multicast not being implemented is that it is quite complex and the purpose it was designed to serve can be served by using authentication at the Application Layer which i think is far enough.

Frankly if operators are really interested in utilising the potential of MBMS (excluding Mobile TV) then they will have to use Multicast sooner or later.

Can anyone think of why Multicast would be better than application layer security?

Thursday 13 September 2007

IMS Updates

Ericsson and Vodafone launched an IMS network in Czech republic this week. Under an agreement signed earlier this year, Ericsson was responsible for delivery and systems integration of its advanced IMS solution, along with project management, network design and implementation. With Ericsson's IMS solution, Vodafone Czech Republic can offer a wide range of next-generation IP telephony and multimedia services towards both fixed and mobile users. It said IMS is an important step towards fixed-mobile convergence. The international-standards-based technology is highly scalable, takes care of connection control, and ensures service quality as well as network and service security.
Aricent, a full-service, full-spectrum communications Software Company, announced this week that it has joined the IMS Forum, the industry's only forum dedicated to the acceleration of IP Multimedia Subsystem (IMS) application and service interoperability. Aricent has a dedicated IMS practice, with more than 800 person years of experience, offering an extensive portfolio of IMS software services and products. The services range from initial strategy and design, through software implementation to system integration and testing for the entire IMS architecture. These services accelerate time-to-revenue for Aricent clients and reduce their risks when deploying IMS-based solutions. With a comprehensive portfolio of IMS software services and products Aricent enables communications equipment manufacturers, device manufacturers and service providers to significantly reduce their time–to-market and mitigate the risks associated with IMS migration and roll-out.
Meanwhile, The IMS Forum, the industry's only Forum delivering IMS services interoperability verification and certification, announced recently that they have signed an MOU with the International Multimedia Telecommunications Consortium (IMTC), an international alliance of companies working together to improve the customer experience and accelerate market adoption of content delivery and unified communications solutions through interoperability of products and services based on open standards. The IMS Forum focuses on interoperability at the IMS Applications and Services Layer across mobile, fixed and cable broadband networks. The IMTC IMS Activity Group focuses on issues surrounding IMS Client interoperability, development and providing feedback to standards organizations.
Under the terms of the agreement, the IMS Forum and the IMTC will establish both a technical liaison between their Technical Working Groups and a marketing liaison. Through these liaisons the two groups will exchange technical information on IMS specifications, testing and interoperability, share interoperability testing best practices, collaborate on technical documents, and organize and participate in future joint testing events. The marketing liaison between the Marketing Working Groups will allow the organizations to share the results of their joint activities with the industry as well as promote this technology's adoption.

Wednesday 12 September 2007

On Header Compression

Was doing some digging into pre-ROHC compression techniques and here they are:

Van Jacobson header compression (VJHC) (RFC 1144) is based on delta coding. The differences between two packet headers are referred to as the “delta”. Instead of transmitting the entire header, VJHC transmits only the delta. This approach achieves high compression. On the downside, it introduces vulnerability. If only one delta coded header is corrupted, all the following packets are erroneous. To recover from these errors and re–establish the current base header, VJHC sends all TCP re–transmissions uncompressed. Thus, VJHC does not require any signaling between compressor and decompressor. The disadvantage is the sensitivity to error–prone links. The Van Jacobson compression scheme was developed to increase the performance of IP/TCP flows over low bandwidth links such as PSTN. It does not even support compression of IP/UDP flows since at that time UDP traffic was very low. This scheme uses delta compression, sending only the difference in the value of the changing fields, to minimize the number of bits sent. It achieves compression from 40 bytes to on an average 4 bytes. It relies on the TCP recovery mechanism to recover from errors in the context due to bit errors and residual errors due to packet loss on the link. This scheme is obviously unsuitable for wireless links and multimedia applications.

Robustness at the cost of less compression was introduced by Perkins and Mutka. In “Dependency Removal for Transport Protocol Header Compression over Noisy Channels,” The delta–coding for the adjacent packets has been replaced by a reference frame. Several consecutive packets are aggregated to a frame. The first packet of a frame is sent uncompressed and the following packets use delta coding with respect to the first (uncompressed) packet in the frame. Clearly, the differences to packets at the end of a frame are larger than for those at the beginning. The compression gain is thus limited (and lower than for VJHC). The advantage of this approach is the usage of shorter delta coding ranges. Corrupted packets do not necessarily lead to the loss of synchronization. This is a clear advantage over VJHC.
IP Header Compression (IPHC) provides a number of extensions to VJHC. The most important extensions are support for UDP, IPv6, and additional TCP features (RFC 2507). With the explicit support of UDP come additional features, such as multicast. Nevertheless, support for RTP is still not given which makes the scheme unsuitable for many multimedia applications. Similar to VJHC, IPHC relies on the change of header fields as well as on the derivation of header field contents. The encoding also employs the delta–scheme, transmitting only the changes in the header fields.
The Compressed Real Time Protocol (CRTP) scheme presented in RFC2508 compresses the 40 bytes header of IP to 4 bytes if the UDP checksum is enabled, or to 2 bytes if it is not. This is possible by compressing the RTP/UDP/IP headers together, similar to the VJHC approach. With the characteristics of the RTP protocol, the changes for the RTP header fields become partially predictable. In addition, changes in some fields are constant over long periods of time. Thus, the expected change in these fields can be implied without even transmitting the differences. These implied fields are also referred to as first order changes. They are stored with the general context for each specific connection. The differences within fields that have to be compressed are referred to as second order differences. An example for these are video frame skips. Video frames are generally transmitted every 40 ms. In case a frame cannot be encoded (e.g., due to lack of processing power or because of a slower play-out ratio), the implied time no longer is accurate. Therefore, the new first order is set to the second order and the connection context is updated. CRTP cannot use a repair mechanism as VJHC does because UDP/RTP are unidirectional protocols without retransmissions.
RObust Checksum–based COmpression (ROCCO) is a refinement of CRTP. ROCCO includes a checksum over the original (uncompressed) header in the compressed header. The checksum facilitates local recovery of the synchronization. In addition, ROCCO incorporates compression profiles (tailored for specific applications, e.g., audio or video streaming) and has a code with hints on the change of header fields in the compressed header. These mechanisms improve the header compression performance, especially for highly error–prone links and long round trip times