802.11 family is getting quite big

Having only studied 802.11a, b and g in past, I was surprised to find that there are many other 802.11 protocols in the family.

See which ones do you know:

• 802.11a - 54 Mbps standard, 5 GHz signaling (ratified 1999)
• 802.11b - 11 Mbps standard, 2.4 GHz signaling (1999)
• 802.11c - operation of bridge connections (moved to 802.1)
• 802.11d - worldwide compliance with regulations for use of wireless signalspectrum (2001)
• 802.11e - Quality of Service (QoS) support (2005)
• 802.11f – Inter access point protocol to support roaming clients (2003)
• 802.11g - 54 Mbps standard, 2.4 GHz signaling (2003)
• 802.11h - Enhanced version of 802.11a to support European regulatory requirements (2003)
• 802.11i - Security improvements for the 802.11 family (2004)
• 802.11j - Enhancements to 5 GHz signaling to support Japan regulatoryrequirements (2004)
• 802.11k - WLAN system management
• 802.11l - Skipped to avoid confusion with 802.11i
• 802.11m - Maintenance of 802.11 family documentation
• 802.11n - Future 100+ Mbps standard
• 802.11o – Voice over WLAN, faster handoff, prioritize voice traffic over data
• 802.11p – Using 5.9GHz band for ITS (long range)
• 802.11q – Support for VLAN 802.11r – Handling fast handoff when roaming between APs
• 802.11s – Self-healing/self-configuring mesh networks
• 802.11t - Wireless Performance Prediction
• 802.11u - Interworking with External Networks
• 802.11v - Wireless Network Management standard
• 802.11w - Protected Management Frames standard
• 802.11x – Summarize all 802.11 standards, but it is not a standard.
• 802.11y - Contention Based Protocol Study Group

For a quick introduction see the following links:

• 3G4G website
• 802.11 Wireless Standards Defined and Discussed By Lee Badman
• 802.11 WLAN Systems – a tutorial

You may also be interested in this new book:

What can mobile operators learn from Laloo

I am sure a lot of you have no Idea who Laloo or 'Lalu Prasad Yadav' is. He was long term chief minister of Bihar state in India is well known for corruption and scandals (as are many other politicians in India). In 2004 he became the Railways Minister of India.

Indian Railways is a very sensitive topic. As much as people like to complain about it, its makes everyone proud. Its one of the biggest railway network in the world, employs over 1.5 million people and the total distance covered by the trains is 3.5 times the distance to moon.

In 2001 an expert declared that Railways will be bankrupt by 2015 unless privatised. It was making huge losses and was expected to make US$15.4 billion loss by 2015. Lalu turned it around in 2-3 years and now its made profit of U$2.47 billion.

To turn this huge organisation from loss making to profit making he followed some simple logic.

• Reduce the fares instead of increasing them and the occupancy will improve
• Increase the freight loading hours from 10 hours to 24 hours daily
• Make everything simple for ordinarly people to follow including reservations
• Once the basics are working keep improving the infrastructure and make further cost reductions

Now lets compare this to how mobile operators behave.

• They provide big subsidy for the handsets but they think this gives them right to charge whatever they wish.
• The tariff's are still not competetive for international calls and while roaming abroad. A simple call making and receiving for a UK mobile on roaming to US can be charged to £1.20 per min. Compare this to making it free using Skype. This puts off so many people in calling home when abroad and receiving calls on their mobiles. If its cheaper more and more people will make and receive calls when abroad.
• Using data abroad could be like commiting suicide.
• There are couple of networks who give huge student discounts but with them text messages can take upto 12 hours to be delivered.
• Some networks have customer service open for limited hours and they charge calling the number even with the same network mobile.

The mobile operators like to complain that the voice call revenues are decreasing and there is still not enough data uptake. I would urge them to set their house in order before they complain. In the end the consumers will always find cheaper alternatives like VoIP and WiFi unless its something important. On the oher hand if some cheap options are available we do not mind trying them.

And the winner is . . . DVB-H

Brussels has now officially endorsed DVB-H as the mobile TV technology of choice in Europe. This means that member states are now required to "encourage" use of the technology, though the commission has no advice as to how to encourage punters to tune in.

In the UK both T-Mobile and Orange are about to launch trials using the competing MBMS (Multimedia Broadcast Multicast Service) technology, which utilises existing 3G networks and spectrum. The technology for that trial is being provided by NextWave Wireless, and CMO Jon Hambidge is dismissive of EU attempts to mandate a mobile TV technology "when [the network operators] spent billions of dollars on their licences MBMS [was] part of that business case".

Note that in an earlier blog I had mentioned that Mobile TV and MBMS will co-exist. See here.

Viviane Reding, EU telecoms commissioner, has made it clear that if companies don't migrate to DVB-H she'll use regulatory measures to create an EU-wide standard.

Background Material:

The DVB-H standard is a recent extension of the DVB-T standard. It is intended to allow reception of television programs with portable and mobile terminals of relatively small size (the H of DVB-H means “handheld,” which indicates the primary type of devices targeted).

In most cases, the terminal will be a mobile phone. In fact, one of the main goals of DVB-H is to avoid the limitation inherent to UMTS of the number of terminals which can receive the same broadcast television program at one time. The main extensions of DVB-H compared to DVB-T are as follows (their use is signaled by specific TPS bits):

• addition of a 4 k COFDM mode, better suited to the implementation of SFN networks of medium cell size and allowing a reduction of the power consumption of the terminal compared to the 8 k mode;
• addition of a longer time interleaving (double for the 4 k mode and quadruple for the 2 k mode), which improves the behavior in case of signal fading and resistance to impulsive noise;

• transmission of a given service in periodic bursts by a process known as “time slicing” which permits a subscriber to activate the receiver only during a fraction of the time (5 to 10%) in order to reduce the power consumption, thus increasing the battery operating time;
• the ability to increase robustness by means of an optional additional link layer error correction (MPE-FEC) to improve the reception with an integrated antenna of necessarily very limited performances.

In order to allow the best use of these extensions, TV programs or other broadcast services are transmitted to mobile terminals as elementary streams (ES) formatted as IP (Internet Protocol) datagrams. The use of the IP protocol is, however, different from the one in TV by ADSL using DVB-IP: in DVB-H, the IP datagrams are encapsulated according to the so-called multiprotocol encapsulation (MPE) and then inserted in an MPEG-2 transport stream for transmission (in DVB-IP, it’s the transport stream which is IP encapsulated). This operation consists of encapsultaing the IP datagrams in DSM-CC sections by adding a header and a CRC termination. These sections are then segmented into MPEG-2 transport packets.

In order to realize the desired time-slicing, sections are not transmitted immediately, but are accumulated in order to form records of a maximum size of 191 kb, which will correspond to the duration of the time slice allocated to a service. These records can be represented as a table of 191 colums by a maximum of 1024 rows on which an optional additional error correction called “MPE-FEC” can be applied. This MPE-FEC consists of a Reed–Solomon coding RS (255,191) applied to words of 191 bytes made of the lines of this table. This will produce a second table made of an RS word of 64 bytes for each line of the original table. The result will be a new table of 255 colums by a maximum of 1024 lines which will be read column by column for transmission.

The DVB-H standard can be used in the UHF TV band with usual DVB-T channel widths (6, 7, or 8 MHz, depending on the region) or in other frequency bands (e.g., L-band in the United States around 1.67GHz with other channel widths, 5MHz in this case).

One of the problems with the use of the UHF band for TV reception in a GSM phone is the proximity of the high part of the UHF band (up to 862 MHz) to the GSM 900 transmit band of the terminal (880 to 915 MHz). Taking into account the current filtering capabilities, this prevents in practice the possibility of using the high UHF channels (>750 MHz) in a TV receiver integrated into an operating GSM phone.

The DVB-H standard can in principle use all the combinations of modulation parameters allowed by the standard (QPSK to 64-QAM, etc.) but, given the required robustness of this application, in practice only QPSK and 16-QAM with FEC of 1/2 or 2/3 are realistically usable, which permits bit-rates of 5 to 11 Mb/s in an 8MHz channel (without MPE-FEC correction). The video encoding used will be mainly H.264 with a CIF or QCIF resolution and bit-rates in the order of 256 to 384 kb/s.

Various experiments took place in Europe from 2004 onward to test the technical performances of the system in order to define the characteristics of the network, and to find out the user acceptance and expectations in order to establish a viable business model. The reactions of the test sample have been positive or enthusiastic everywhere. The first commercial DVB-H services started in Finland and Italy in mid-2006.

For more information see:

Healthcare using BWA (Broadband Wireless Access)

Came across this paper entitiled "IEEE 802.16/WiMAX-based broadband wireless access and its application for telemedicine/e-health services". While it is common sense that any prehospital diagnosis and monitoring can be very helpful it is important to make sure that the information is updated properly and with correct QoS.

Ambulances and other medical emergency vehicles travel at extremely high speeds. This would require that the technology in place is able to handover between different cells and keeps the equipment connected to the server. The nurse should concentrate on the patient rather than worry about the link being maintained electronically. This also necessitates a quaranteed QoS being maintained for this setup to work effectively. The figure above shows the QoS that is required in different situations.

In the above mentioned paper, the authors argue that WiMAX/802.16 networks can be engineered for telemedecine/e-health services. The main focus should be on Radio Resource allocation and admission control policy. Other important thing is to remember while implementing to use TCP for loss sensitive data and UDP for delay sensitive (but loss in-sensitive) applications.

I am sure the healthcare industry is already looking in these kinds of options and its just matter of time before we will hear about some new related application.

Japanese (and Koreans) only want 3G+

According to this news on Yahoo, Japanese stores took delivery of no second-generation mobile telephones in January for the first time since their launch as shipments of advanced handsets soared, an industry group said Tuesday.

Japan and South Korea are at the forefront of third-generation (3G) phones, which offer high-speed Internet access and other interactive features and have not even entered the market in many developing nations.

Manufacturers sent 4.08 million cellphones to Japanese stores in January, the Japan Electronics and Information Technology Industries Association said.

"For the first time, the number of second-generation models was zero," it said.
Japan becomes the second country to be virtually finished with second-generation following South Korea, according to Nomura Research.

Japanese stores continue to offer a small number of second-generation phones, but it is almost impossible for new users to start fresh subscriptions.

At the end of February, nearly 85 percent of Japanese mobile users were carrying third-generation or equivalent phones. Japan's top-ranked NTT DoCoMo Inc. in 2001 became the world's first company to offer 3G.

Despite the success in Japan and South Korea, 3G has caught on more slowly in other countries amid questions over whether customers will pay much steeper prices for features they could find on their home computer.

Third-generation or advanced second-generation accounts for about 50 percent of North American cellphones and 10 percent of Western European mobiles, according to industry surveys.

In Japan, mobile operators have increasingly written off second-generation phones as a source of profit and have been developing more advanced features to woo customers.
More than 60 percent of the phones delivered by manufacturers in January are equipped for digital television broadcasts.

Japan began digital broadcasts in 2006 that allow mobile phone users to watch several hours of interrupted television on their phones without recharging the battery.
"It's the third straight month that such phones make up more than half of the mobile phones," the industry association said.

Some 20 million Japanese now have phones to watch digital broadcasts, which major networks offer for free.

muni Wi-Fi: What an amazing concept

There is this anazing concept of public Broadband (also known as municipal WiFi or muni WiFi). The local council or municipalty installs WiFi across a big area, town or city and this is an unprotected network open to public.

U.S. is pioneer of this concept and they have been planning or rolling it out across many cities. Have a look at this Top 10 Municipal WiFi Plans from Businessweek for more info.

ABI Research forecasts that the total global area covered by municipal Wi-Fi will expand nearly sixty-fold from 520 square miles in 2004 to 30,000 square miles in 2012.

The analyst firm said that the US leads in municipal Wi-Fi deployments, but that Canada, Japan, South Korea and Western Europe are rapidly expanding municipal Wi-Fi infrastructure and applications.

Varying levels of maturity and acceptance exist within the market, spread across global regions and individual countries.

ABI believes that the US employs the wrong business plan of free consumer access and free infrastructure, and that incumbent service providers view municipal Wi-Fi as a competitive threat.

In Europe, mobile-oriented rather than PC-oriented incumbents initially resisted municipal Wi-Fi but now recognise in-building limitations.
Stan Schatt, vice president and research director at ABI Research, highlighted key financial benefits that should be included in the municipal Wi-Fi business case.

"Wireless surveillance systems, for example, will provide financial returns by helping prevent possible terrorist attacks, decreasing overall crime, improving traffic flow, and even boosting tourism by creating stable communities," he said.

Once the technology, business and cost issues are resolved, however, Schatt predicts that nations will benefit from this simple and low-cost broadband internet access technology, consequently broadening the range of networked services.

Ofcourse not everyone is happy and everyone has their own opinion on how it should run.

There is also ad powered WiFi hotspots springing up in different places which will provide higher speeds than compared to this muni Wi-Fi but you will have to click on some ad every hour or two and once WiMAX is commonly available this muni Wi-Fi thing may seem like an expensive experiment because with WiFi there needs to be a router or repeater every few hundred metres which takes effort to install and maintain and is expensive peice of equipment. Lets see what happens.

MXtv or MAXtv

NextWave MXtv(TM) is a breakthrough mobile multicast and broadcast technology that enables WiMAX operators to deliver a broad range of rich and personalized multimedia services including mobile TV, interactive media services, and digital audio for a more compelling subscriber experience. An innovative broadcast solution, NextWave MXtv does not require any additional spectrum and uses existing radio access network equipment providing operators with an entirely new business model to increase revenues and achieve profitability. With MXtv, WiMAX wireless operators can effectively manage their valuable spectrum resources by dynamically balancing bandwidth allocated to broadcast services with on demand services.

So we now have Mobile TV over WiMAX which i personally think is quite good. Unfortunately the Mobile TV services havent caught up with general public yet but the operators have themself to blame quite a bit for this. The pricing is not friendly and then a lot of times, the content is not very friendly. The online portal designers dont understand how to categorise the content so someone doesnt have to browse for 5 minutes to reach their favourite item.

Anyway, this Mobile TV thing is a really good option along with MBMS, TDtv, DVB-H, T-DMB, MediaFLO, etc., etc.

EE Times news item combines couple of press releases:

NextWave Wireless Inc. has signed a strategic deal with Alcatel-Lucent over the WiMAX-based mobile TV platform it announced earlier this week.

The agreement calls for Alcatel-Lucent to integrate NextWave's MXtv technology into its WiMAX portfolio, based on the 802.16e-2005 (Rev-e) standard.

The companies also plan to perform a series of interoperability tests with Alcatel-Lucent's commercial WiMAX infrastructure starting in the second quarter of this year.

In a separate deal, Chinese communications gear supplier Huawei also said this week it would integrate the MXtv technology into its own WiMAX networking kit.

The MXtv technology has also been integrated into NextWave's low-power, Wave 2 compliant NW2000 series WiMAX subscriber device SoC. The device is currently being integrated into a wide range of devices with some device availability planned for second half of 2008.

The technology is based on the TDtv mobile TV platform NextWave (San Diego, Calif.) gained access to through the acquisition last year of UMTS-TDD kit supplier IP Wireless (Chippenham, England).

NextWave says its latest broadcast technology will allow WiMAX operators to deliver rich and personalized multimedia services including mobile TV, interactive media, and digital audio. NextWave said that macro-diversity technology is used to improve the broadcast performance over the WiMAX channel.

The offering promises 30fps QVGA and WQVGA content and up to 45 high quality mobile TV channels in 10MHz with channel switching times below two seconds.

Network operators can also dynamically allocate spectrum based on content availability, time of day requirements, user demand, and the availability of live events such as sports, concerts, interactive reality shows or emergency broadcasts.

"User demand for mobile broadcast services is rapidly expanding and we believe that the exciting new applications offered through this alliance will provide mobile operators a unique ability to deliver the key differentiating feature of 4G networks," said Allen Salmasi, CEO of NextWave Wireless.

On OFDMA ...

Last year I wrote a blog on the difference between OFDM and OFDMA. Lots of people found it useful.

With OFDM/OFDMA being discussed everywhere, I thought of linking an article which would give everyone quick info on these technologies. This article from Network Systems Designline titled "Understanding OFDMA, the interface for 4G wireless" is split into two parts:

1st is Introduction to OFDM

2nd is on OFDMA

Let me know if you found these of use.

Nokia Morph Concept Phone

This Nokia Morph Concept phone looks quite cool.

Launched alongside The Museum of Modern Art “Design and The Elastic Mind” exhibition, the Morph concept device is a bridge between highly advanced technologies and their potential benefits to end-users.

The first thing is to actually check this Demo at Nokia site which will give you a very good idea of this.

IPv6! One small step for man, one giant leap for mankind

3G Americas has published a whitepaper urging wireless service providers to start making a transition plan asap.

Anyone who has studied TCP/IP in their studies would know the basic problem with IPv4 is that the address is only 32 bits long and this allows a theoretical maximum of 2^32 addresses. Ofcourse practically the number would be far less because some of the address are either reserved or wasted due to the way the networks are designed (Subnets, etc).

To overcome this sometime in the beginning of 1990's IPv6 was formulated with 128 bit address. This would mean unique IP address to every street lamp is possible without us worrying about depletion of the addresses. Ofcourse the human nature is such that they dont change their behaviour untill forced to and this is the same reason IPv6 is not been used popularly.

When 3G was being standardised one of the main goals was also to use IPv6 exclusively but then everyone chickened out citing various problems and continuity of services.

Anyway, this new 3G Americas paper has laid down a plan and possible pitfalls that would be encountered when transitioning to IPv6. The following is a self explanatory summary for the report:

To transition to IPv6 or not? A critical question for many service providers is when to transition to IPv6. As pointed out earlier, IPv6 has several benefits which will result in a simpler, more powerful and more efficient network. The sooner a service provider achieves these benefits, the sooner it will be at a competitive advantage compared to service providers who delay transition. The risks of delaying the transition are the following:

 Managing a dwindling IPv4 address space will become increasingly expensive. Address
allocation requires careful planning; previously assigned address blocks may need to be
recovered, which is a complex process; and the management of additional devices such as
Network Address Translation (NAT) devices add to the cost.

 The service provider that delays transition to IPv6 may not be able to deliver the same
services as service providers that have made the transition to IPv6. The ability to support
always-on and peer-to-peer services is impaired when traffic has to traverse NAT devices.
For example, always-on services require that a user is always reachable and therefore
cannot share a pool of public addresses with other devices. This can be mitigated through
address and port translation, but also that has its limitations.

 At some point, a service provider who has not made the transition to IPv6 may become
unattractive as a roaming partner to service providers who have made the transition. The
same may be true in retail/wholesale relationships.

On the other hand, transitioning to IPv6 at an early stage also has certain risks. The transitioning process is complex. It requires a significant investment in planning and training. During the transition period, the service provider must run both IPv4 and IPv6 systems concurrently, which leads to an increase in operational expenses. Furthermore, there is a risk of service interruption, customer dissatisfaction and penalties. All service providers will need to go through this, but an early adopter may run into problems which later adopters could avoid.

In the end, we believe that service providers don’t have the option to delay IPv6 introduction. The exhaustion of IPv4 addresses will force a transition to IPv6, and as pointed out earlier, address exhaustion may become a reality within the next five years. From that point on, service providers will face an increase in operations cost, if not because of introduction of IPv6, then due to the complexity of running an IPv4-only network with a diminishing pool of addresses.

With careful planning, the risk of early adoption can be mitigated significantly.