Hey did you check www.cuil.com (Google's new competition)???

Google's new competition: Ex-employees

“Cuil has indexed a whopping 120 billion Web pages, three times more than what they say Google now indexes”

Check the below information for more on cuil……..

Cuil is an old Irish word for knowledge. For knowledge, ask Cuil.

A start-up led by former star Google engineers has unveiled a new Web search service that aims to outdo the Internet search leader in size, but faces an uphill battle changing Web surfing habits.

Cuil Inc (pronounced "cool") is offering a new search service at http://www.cuil.com/ that the company claims can index, faster and more cheaply, a far larger portion of the Web than Google, which boasts the largest online index.

The would-be Google rival says its service goes beyond prevailing search techniques that focus on Web links and audience traffic patterns and instead analyzes the context of each page and the concepts behind each user search request.

"Our significant breakthroughs in search technology have enabled us to index much more of the Internet, placing nearly the entire Web at the fingertips of every user," Tom Costello, Cuil co-founder and chief executive, said in a statement.

Danny Sullivan, a Web search analyst and editor-in-chief of Search Engine Land, said Cuil can try to exploit complaints consumers may have with Google -- namely, that it tries to do too much, that its results favour already popular sites, and that it leans heavily on certain authoritative sites such as Wikipedia.

"The time may be right for a challenger," Sullivan says, but adds quickly, "Competing with Google is still a very daunting task, as Microsoft will tell you."

Microsoft Corp, the No. 3 US player in Web search has been seeking in vain, so far, to join forces with No. 2 Yahoo Inc to battle Google.

Cuil was founded by a group of search pioneers, including Costello, who built a prototype of Web Fountain, IBM's Web search analytics tool, and his wife, Anna Patterson, the architect of Google Inc's massive TeraGoogle index of Web pages.

Patterson also designed the search system for global corporate document storage company Recall, a unit of Australia's Brambles Ltd.

The two are joined by two former Google colleagues, Russell Power and Louis Monier. Previously, Monier led the redesign of ecommerce leader eBay Inc's search engine and was the founding chief technology officer of two 1990s Web milestones, AltaVista and BabelFish, the first language translation site.

"They do have the talent that is used to build large, industrial-strength search engines," Sullivan says of Cuil.

Cuil clusters the results of each Web search performed on the service into groups of related Web pages. It sorts these by categories and offers various organising features to help identify topics and allow the user to quickly refine searches.

User privacy is another appeal of its approach, Cuil says. Because the service focuses on the content of the pages rather than click history, the company has no need to store users' personal information or their search histories, it says.

"We are all about pattern analysis," Patterson says. "We go over the corpus (Web pages) 12 times before we even index it."

Does size matter, once again? Cuil has indexed a whopping 120 billion Web pages, three times more than what they say Google now indexes, Patterson said, adding the company has spent just $5 million, Google itself preemptively responded to Cuil's arrival with a blog post on Friday boasting of the growing scale of its own Web search operations.

Sullivan said he puts no stock in either company's boasts about the size of their indexes, since it has only an indirect effect on the ultimate success Web surfers have in searching. And Cuil's privacy virtues are exaggerated, he adds.

Founded in late 2006, the Menlo Park, California-based Cuil has raised $33 million in two separate rounds: The first, for $8 million from Greylock and Tugboat Ventures, and the second for $25 million by Madrone Capital Partners.

Initially, Cuil is optimised for American English. Later this year, the company plans to enable Cuil users to perform searches in major European languages, Patterson said. Eventually, Cuil plans to make money by running ads alongside search results, she said, but provided no further details.

Cuil is one of a number of start-ups that are looking to introduce new technology that can change the competitive dynamics of the Web search market that Google dominates.

Earlier in July, Microsoft bought Powerset, a San Francisco-based search start-up that enables consumers to use semantic techniques -- conversational phrasing instead of keywords -- to search the Web.

MOORE'S LAW and New material called Hafnium

Technical information that I read always makes me to share the things to all other technical persons I come accross......

The silicon industry has already introduced new materials such as Hafnium





For more than 40 years the silicon industry has delivered ever faster, cheaper chips.
The advances have underpinned everything from the rise of mobile phones to digital photography and portable music players.


Chip-makers have been able to deliver many of these advances by shrinking the components on a chip.


By making these building blocks, such as transistors, smaller they have become faster and firms have been able to pack more of them into the same area.
But according to many industry insiders this miniaturisation cannot continue forever.



"The consensus in the industry is that we can do that shrink for about another ten years and then after that we have to figure out new ways to bring higher capability to our chips," said Professor Stanley Williams of Hewlett Packard.


MOORE'S LAW
The number of transistors it is possible to squeeze in to a chip for
a fixed cost doubles every two years
First outlined by Gordon Moore, co-founder of Intel
Published in Electronics Magazine on 19 April, 1965


Even Gordon Moore, the founder of Intel and the man that gave his name to the law that dictates the industry's progression, admits that it can only go on for a few more years.
"Moore's Law should continue for at least another decade," he recently told the BBC News website. "That's about as far as I can see."


Tiny tubes:
As a result, researchers around the world are engaged in efforts to allow the industry to continue delivering the advances that computer users have come to expect.
Key areas include advanced fabrication techniques, building new components and finding new materials to augment silicon.
Already new materials are creeping into modern chips.
As components have shrunk critical elements of the transistors, known as gate dielectrics, do not perform as well allowing currents passing through the transistors to leak, reducing the effectiveness of the chip.
To overcome this, companies have replaced the gate dielectrics, previously made from silicon dioxide, with an oxide based on the metal hafnium.
The material's development and integration into working components has been described by Dr Moore as "the biggest change in transistor technology" since the late 1960s.
But IBM researchers are working on materials that they believe offer even bigger advances.
"Carbon nanotubes are a step beyond [hafnium]," explained Dr Phaedon Avouris of the company.

'Superior' design:
Carbon nanotubes are tiny straw-like molecules less than 2 nanometres (billionths of a metre) in diameter, 50,000 times thinner than a strand of a human hair.
"They are a more drastic change but still preserve the basic architecture of field effect transistors."
These transistors are the basic building blocks of most silicon chips.
Dr Avouris believes they can be used to replace a critical element of the chip, known as the channel.
Today this is commonly made of silicon and is the area of the transistor through which electrons flow.
Chip makers are constantly battling to make the channel length in transistors smaller and smaller, to increase the performance of the devices.
Carbon nanotube's small size and "superior" electrical properties should be able to deliver this, said Dr Avouris.
Crucially, he also believes the molecules can be integrated with traditional silicon manufacturing processes, meaning the technology would more likely be accepted by an industry that has spent billions perfecting manufacturing techniques.
The team have already shown off working transistors and are currently working on optimising their production and integration into working devices.

Tiny improvement:
Professor Williams, at Hewlett Packard is also working on technology that could be incorporated into the future generations of chips.
As well as exploring optical computing - using particles of light instead of electrons to significantly increase the speed of today's computers - he is building new electronic components for chips called memristors.
He says it would be the "fourth" basic element to build circuits with, after capacitors, resistors and inductors.
"Now we have this type of device we have a broader palette with which to paint our circuits," said Professor Williams.
Professor Williams and his team have shown that by putting two of these devices together - a configuration called a crossbar latch - it could do the job of a transistor.
"A cross bar latch has the type of functionality you want from a transistor but it's working with very different physics," he explained.
Crucially, these devices can also be made much smaller than a transistor.
"And as they get smaller they get better," he said.
Professor Williams and his team are currently making prototype hybrid circuits - built of memristors and transistors - in a fabrication plant in North America.
"We want to keep the functional equivalent of Moore's Law going for many decades into the future," said Professor Williams.

BEAUTIFUL BUTTERFLIES

ESOL ET-KERNEL/EXTENDED RTOS FOR I.MX31 PROCESSOR

eSOL eT-Kernel/Extended RTOS for i.MX31 Processor:

eSOL recently announced the eT-Kernel/Extended realtime operating system (RTOS) coupled with the eBinder integrated development environment (IDE) for the i.MX31 multimedia applications processor from Freescale. eT-Kernel/Extended supports a process model and memory protection with a memory management unit (MMU), and is based on the latest T-Kernel/Standard Extension specifications standardized by the T-Engine Forum. The memory-protected and process-model RTOS detects and prevents an executing process from accidentally destroying another process's memory area or kernel resource.

eT-Kernel/Extended offers a UNIX-like process management function using virtual addressing. Each component can be divided into a distinct process, independent of others. Development and debugging by process is perfect for a large team working on a large system that consists of multiple independent software modules, such as audio/video codecs, 2D/3D user interface engines, device drivers, firmware, middleware, and applications. eT-Kernel/Extended also offers a process for building upper-layer applications, and a system program for building kernel applications, including loadable drivers and middleware. This combination is best for a large team developing a large system because the entire system can be designed and developed in parts instead of one team working on everything. In addition, a mixture of shared libraries and DLLs can be used from a process, making system configuration flexible while saving memory space.

Freescale's i.MX31 multimedia applications processors, based on the ARM11(tm) core, are high-performance mobile entertainment engines for the ultimate multimedia experience. The devices have a built-in Image Processing Unit (IPU) that includes the functionality required for image processing and display management. This includes deblock, dering, color space conversion, independent horizontal and vertical resizing, blending of graphics and video planes, and rotation in parallel to video decoding. The IPU accelerates loop deblocking for H.264 decode as well as encode. It is engineered to provide acceleration of image processing to deliver up to VGA 25 fps video quality.

Inspite of being such a complicated Railway network, we never hear about any accidents in Frankfurt Germany

SURFACE-CONDUCTION ELECTRON-EMITTER DISPLAY (SED)

Surface-Conduction Electron-Emitter Display (SED):

A Surface-conduction Electron-emitter Display (SED) is a flat panel display technology that uses surface conduction electron emitters for every individual display pixel. The surface conduction electron emitter emits electrons, that excite a phosphor coating on the display panel which is similar to the basic concept found in traditional cathode ray tube (CRT) televisions. This means that SEDs can combine the slim form factor of LCDs with the high contrast ratios and can also refresh rates making the picture quality of CRTs better .The researches so far claim that the SED consumes less power than the LCD displays. The surface conduction electron emitter apparatus consists of a thin slit, across which electrons tunnel when excited by moderate voltages (tens of volts).

When the electrons cross electric poles across the thin slit, some are scattered at the receiving pole and are accelerated towards the display surface by a large voltage gradient (tens of kV) between the display panel and the surface conduction electron emitter apparatus. The SED display offer brightness, color performance and viewing angles on par with CRTs. However, they do not require a deflection system for the electron beam. Engineers as a result can create a display that is just a few inches thick which is still light enough for wall-hanging designs. The manufacturer can enlarge the panel merely by increasing the number of electron emitters relative to the necessary number of pixels. Since 1987, SED technology has been developing. Canon and Toshiba are the two major companies working on SEDs.

MAGNATORESISTIVE RAM (MRAM)

MAGNATORESISTIVE RAM (MRAM):

MRAM, the new breed of semiconductor memory uses magnetic properties to store data. This new kind of chip will compete with other established forms of semiconductor memories such as Flash memory and random access memory (RAM). Most engineers believe that the technology called magnetoresistive random - access memory (MRAM) could reduce the cost and power consumption of electronics for cell phones, music players, laptops and servers.

The feature, that makes MRAM an alluring alternative to other forms of semiconductor memories, is the way it stores data. For example, flash memory and random-access memory (RAM) hold information as electric charge. In contrast, MRAM uses the magnetic orientation of electrons to represent bits. Using MRAM, reading and writing of data can be done unlimitedly with in nanoseconds. MRAM can also hold the data without a power supply.

4G

4G:

The technology called 4G has redefined the whole concept of today’s sophisticated communication. According to the Wireless World Research Forum (WWRF), 4G is a combination of wired and wireless networks in computer, consumer electronics and communication technology systems based on the internet technology, that can merge applications like the Wi-Fi and WiMAX capable of transmitting at a speed ranging from 100 Mbps (in cell-phone networks) to 1 Gbps (in local Wi-Fi networks).

This collection of technologies and protocols delivers high quality of service at both ends and high point security. Officially named by IEEE as Beyond 3G (B3G) it provides with the lowest cost wireless network.

CELL PHONE VIRUSES AND SECURITY

CELL PHONE VIRUSES AND SECURITY:

As cell phones become a part and parcel of our life so do the threats imposed to them is also on the increase. Like the internet, today even the cell phones are going online with the technologies like the edge, GPRS etc. This online network of cell phones has exposed them to the high risks caused by malwares viruses, worms and Trojans designed for mobile phone environment. The security threat caused by these malwares are so severe that a time would soon come that the hackers could infect mobile phones with malicious software that will delete any personal data or can run up a victim’s phone bill by making toll calls.

All these can lead to overload in mobile networks, which can eventually lead them to crash and then the financial data stealing which poises risk factors for smart phones. As the mobile technology is comparatively new and still on the developing stages compared to that of internet technology, the antivirus companies along with the vendors of phones and mobile operating systems have intensified the research and development activities on this growing threat, with a more serious perspective.

SYNCML

SyncML:

The popularity of mobile computing and communications devices can be traced to their ability to deliver information to users when needed. Users want ubiquitous access to information and applications from the device at hand, plus they want to access and update this information on the fly.

The ability to use applications and information on one mobile device, then to synchronize any updates with the applications and information back at the office, or on the network, is key to the utility and popularity of this pervasive, disconnected way of computing.

Unfortunately, we cannot achieve these dual visions:
1. Networked data that support synchronization with any mobile device
2. Mobile devices that support synchronization with any networked data

Rather, there is a proliferation of different, proprietary data synchronization protocols for mobile devices. Each of these protocols is only available for selected transports, implemented on a selected subset of devices, and able to access a small set of net-worked data. The absence of a single synchronization standard poses many problems for end users, device manufacturers, application developers, and service providers.

SyncML is a new industry initiative to develop and promote a single, common data synchronization protocol that can be used industry-wide. Driving the initiative are Ericsson, IBM, Lotus, Motorola, Nokia, Palm Inc., Psion, Starfish Software. Additional companies are being recruited to join and participate.

The SyncML initiative recognized the worldwide need for one common data synchronization protocol. With the industry-wide proliferation of mobile devices and the evolution toward mobile devices as the major means of information exchange, remote synchronization of data will be of integral importance. The SyncML initiative, officially supported by well over 200 device manufacturers, service providers and application developers, is currently developing and promoting an open global specification for mobile data synchronization.

SMARTQUILL

Smartquill:


Lyndsay Williams of Microsoft Research’s Cambridge UK lab is the inventor of the Smartquill, a pen that can remember the words that it is used to write, and then transform them into computer text. The idea that it would be neat to put all of a handheld-PDA type computer in a pen came to the inventor in her sleep. “It’s the pen for the new millennium,” she says. Encouraged by Nigel Ballard, a leading consultant to the mobile computer industry, Williams took her prototype to the British Telecommunications Research Lab, where she was promptly hired and given money and institutional support for her project. The prototype, called SmartQuil, has been developed by world-leading research laboratories run by BT (formerly British Telecom) at Martlesham, eastern England. It is claimed to be the biggest revolution in handwriting since the invention of the pen.

The sleek and stylish prototype pen is different from other electronic pens on the market today in that users don’t have to write on a special pad in order to record what they write. User could use any surface for writing such as paper, tablet, screen or even air. The SmartQuill isn’t all space-age, though -- it contains an ink cartridge so that users can see what they write down on paper. SmartQuill contains sensors that record movement by using the earth’s gravity system, irrespective of the platform used. The pen records the information inserted by the user. Your words of wisdom can also be uploaded to your PC through the “digital inkwell”, while the files that you might want to view on the pen are downloaded to SmartQuill as well.

It is an interesting idea, and it even comes with one attribute that makes entire history of pens pale by comparison—if someone else picks your SmartQuill and tries to write with it- it won’t. Because user can train the pen to recognize a particular handwriting. Hence SmartQuill recognizes only the owner’s handwriting. SmartQuill is a computer housed within a pen which allows you to do what a normal personal organizer does. It’s really mobile because of its smaller size and one handed use. People could use the pen in the office to replace a keyboard, but the main attraction will be for users who usually take notes by hand on the road and type them up when returning to the office. SmartQuill will let them skip the step of typing up their notes.

Technical Seminar / Essays topics

Technical Seminar / Essays topics:

Learning to write well is one of the most challenging tasks for anyone, regardless of age.

It takes time, practice, and lots of encouragement.
Parents, teachers and knowledgeable persons can help children / others develop their skills and, equally important, a love for words and writing.

A seminar should aim to:

*The Seminar topic have good technical content
*Seminar should be understood by the audience
*Be accompanied by appropriate handouts
*The Seminar should be interactive

General Essay Writing Tips

General Essay Writing Tips:

1. Step One: Brainstorming - The most important part of your essay is the subject matter. You should expect to devote about 1-2 weeks simply to brainstorming ideas. Having completed step one, you should now have a rough idea of the elements you wish to include in your essay, including your goals, important life experiences, research experience, diversifying features, spectacular nonacademic accomplishments, etc. You should also now have an idea of what impression you want to make on the officers.

2. Step Two: Selecting a Topic - After evaluating your essay topics with the above criteria and asking for the free opinions of your teachers or colleagues, and of your friends, you should have at least 1-2 interesting essay topics.

3. Step Three: Writing the Essay - Even seemingly boring topics can be made into exceptional admissions essays with an innovative approach.
Unfortunately, there is no surefire step-by-step method to writing a good essay.

But still following few steps can make the essay successful:

01 - Answer the question – Check what are all the questions that will arise from the Essay that you will present.
02 - Be original - Even seemingly boring essay topics can sound interesting if creatively approached.
03 - Be yourself
04 - Don't thesaurize your composition - For some reason, students continue to think big words make good essays. Big words are fine, but only if they are used in the appropriate contexts with complex styles. Think Hemingway.
05 - Use imagery and clear, vivid prose
06 - Spend the most time on your introduction - Expect officers to spend 1-2 minutes reading your essay. You must use your introduction to grab their interest from the beginning.
07 - Body paragraphs must relate to your introduction - Your introduction can be original, but cannot be silly. The paragraphs that follow must relate to your introduction.
08 - Use transition - You must use transition within paragraphs and especially between paragraphs to preserve the logical flow of your essay.
09 - Conclusions are critical - The conclusion is your last chance to persuade the reader or impress upon them your qualifications.
10 - Do something else
11 - Give your draft to others
12 - Revise, revise, and revise

In writing the essay you must bear in mind your two goals:
1. Allow for the evolution of your main topic.
2. Do not assume your subject must remain fixed and that you can only tweak sentences.

Editing takes time: Consider reordering your supporting details, delete irrelevant sections, and make clear the broader implications of your experiences. Allow your more important arguments to come to the foreground. Take points that might only be implicit and make them explicit. To persuade the officer that you are extremely worthy of and to make the officer aware that you are more than a GPA and a standardized score, that you are a real-life, intriguing personality.

How To Write A Good Technical Essay

How To Write A Good Technical Essay??

For students in undergraduate and Master's degree programs, writing a good technical essay means earn good grades.

For college and graduate students, writing a good technical essay means good grades. If you are one of those college and graduate students who want to finish their studies with flying colours, you must learn the basic principles of technical essay writing. To help you write a good essay and earn good grades, here are five easy steps for you.



1. Following Instructions:

If your professor specifies essay topics for you to write on, make sure that you write your technical essay according to the instructions provided. The best way to please your professor is to follow instructions and make his or her life easier when reviewing your essay. Always remember that your professor have to review hundreds of essays from other students in his or her classes.

2. Formulating Your Thesis:

Just because your professor provided you with a topic for your technical essay doesn't mean you’re professor controls what you have to say about the essay topic. You need to come up with a good thesis for your essay. A thesis contains the point or points that you want to say and to prove in your essay. When formulating your thesis, you need to take an interesting stand on the topic and then proceed to argue your point in your technical essay.

3. Structuring Your Technical Essay:
When structuring your technical essay, make sure that you follow the basic principles of academic writing. You need to have an introduction in your technical essay. When you introduce the topic in your essay, write fairly general statements at first and then gradually narrow down the discussion in your essay to a specific thesis. Establish the thesis of your essay well from the very beginning and create a strong impact on the reader. Always remember that your readers will want to know what you are driving at right from the start.
The body of your technical essay contains statements that support your thesis. Use a review of related literatures to support your arguments and remember to always acknowledge your sources. Do not plagiarize the work of others. Come up with your own arguments and simply use the review of related literatures to strengthen your position. Always remember that in academic writing, you need to be accurate in your facts. Your arguments will be worthless if you cannot support them with facts and figures.
Your technical essay must contain a conclusion. You need to sum up all your arguments in the conclusion of your technical essay. When writing the conclusion for your technical essay, you start by summing up the specific arguments of your essay and then gradually expand it to general discussions. In other words, your conclusion will need to clench all your arguments to make a strong ending.

4. Review Your Work:
Before you submit your technical essay to your professor, make sure that you review your work several times. You need to write and rewrite your technical essay a few times over to make sure that you have a good quality essay that is free from grammatical mistakes, typographical errors and all material is properly cited.

Poor India makes millionaires at fastest pace

WASHINGTON: India, with the world's largest population of poor people living on less than a dollar a day, also paradoxically created millionaires at the fastest pace in the world in 2007 even though the world grew such "high net worth individuals (HNWIs)" at the slowest pace in four years.
Growing them at a blistering pace of 22.7 per cent, India added another 23,000 more millionaires in 2007 to its 2006 tally of 100,000 millionaires measured in dollars, according to an annual Merrill Lynch Cap Gemini report that weighs such financial information for its wealth and asset management purposes.
In contrast, developmental agencies put the number of subsistence level Indians living on less than a dollar a day at 350 million and those living on less than $ 2 a day at 700 million. In other words, for every millionaire, India has about 7000 impoverished people.
While India's HNWI population growth of 22.7 per cent in 2007 exceeded China's 20.3 per cent and its own 2006 gains of 20.5 in 2006, it was still way below its giant neighbour in absolute number of millionaires. China counted nearly 500,000 HNWIs.
Overall, the numbers of millionaires (not counting home values in their assets) in the world grew at 9.4 per cent and crossed the 10 million mark for the first time. The United States, despite its economic woes, led the pack of Richie Rich's with more than three million millionaires, i.e., one in every three millionaires in the world lives in America.
The combined wealth of the globe's millionaires grew to nearly $41 trillion last year, which means their average wealth was more than $4 million, the highest it's ever been.
In measuring the millionaire mob in India, the Merrill Lynch Cap Gemini report looked at metrics for the year 2007, which means it did not take into account the precipitous stock market slide that has wiped out nearly a third of the market value in 2008.
"India led the world in HNWI population growth at 22.7 percent, driven by market capitalization growth of 118 percent and real GDP growth of 7.9 percent. Although India's real GDP growth decelerated from 9.4 percent in 2006, current levels are considered more stable and sustainable," the report observed.
It also ranked India's two largest exchanges – the Bombay Stock Exchange and the National Stock Exchange – among the world's top 12 exchanges by end of 2007, "with growth rates of 122% and 115% respectively....that were boosted by initial public offering markets and heightened international interest."
Explaining the faster rate of growth of millionaires in India than in China, the report suggests that as market capitalization and real GDP in China were spread over a larger population, there were smaller per capita gains in China. In 2006, India had a larger market capitalization growth than gross national income, significantly impacting HNWI population growth.
In addition, it said, China is currently experiencing explosive growth in its "mass affluent" population, which has yet to break the HNWI threshold of US$1million.
The observation also suggests China is having greater equitable growth than India.

'Migrant Thackerays came to Mumbai for jobs'

MUMBAI: The Thackerays came to Mumbai two generations ago for jobs and as such have no right to assault those coming to the financial capital in search of livelihood.

This claim has been made in an article published in this month's issue of Nationalist Congress Party's mouthpiece Rashtravadi , whose chief Sharad Pawar is an old friend of Shiv Sena supremo Bal Thackeray.

Hari Narke, professor at Mahatma Phule chair in Pune University and a renowned scholar on Ambedkar, has written the strong-worded article.

Narke has flayed Maharashtra Navnirman Sena Chief Raj Thackeray, who is Bal Thackeray's nephew, over attacks on migrants in Mumbai.

"Raj should read the autobiography of his grandfather Prabodhankar Thackeray (Bal Thackeray's father). Prabodhankar, who studied in Madhya Pradesh, has written how he travelled in other states for livelihood", Narke says.

"This proves that the Thackerays, who are not original inhabitants of Mumbai, came to this city in search of livelihood", the scholar says.

Incidentally, Prabodhankar's literature was published in 1995 by Maharashtra Government at the behest of Narke, the article says.

"Who gave those, who came to Mumbai two generations ago to earn their livelihood, the right to beat up others who also come here in search of jobs?", Narke has questioned.

"It does not behove people who live 24 hours a day seeped in history to forget the history of just over two generations", Narke said.

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'Mobile Telephone Systems' (Information that I have collected)

Mobile Phone System:

Cellular, personal communication service (PCS), and third generation 3G mobile radio systems are all cellular wireless communication networks that provide for voice and data communication throughout a wide geographic area. Cellular systems divide ‘large geographic areas’ area into small radio areas (cells) that are interconnected with each other. Each cell coverage area has one or several transmitters and receivers that communicate with mobile telephones within its area.

The cellular system connects mobile radios (called mobile stations) via radio channels to base stations. Some of the radio channels (or portions of a digital radio channel) are used for control purposes (setup and disconnection of calls) and some are used to transfer voice or customer data signals. Each base station contains transmitters and receivers that convert the radio signals to electrical signals that can be sent to and from the mobile switching center (MSC). The MSC contains communication controllers that adapt signals from base stations into a form that can be connected (switched) between other base stations or to lines that connect to the public telephone network. The switching system is connected to databases that contain active customers (customers active in its system). The switching system in the MSC is coordinated by call processing software that receives requests for service and processes the steps to setup and maintain connections through the MSC to destination communication devices such as to other mobile telephones or to telephones that are connected to the public telephone network.

When linked together to cover an entire metro area, the radio coverage areas (called cells) form a cellular structure resembling that of a honeycomb. Cellular systems are designed to overlap each cell border with adjacent cell borders to enable a “hand-off” from one cell to the next. As a customer (called a subscriber) moves through a cellular system, the mobile switching center (MSC) coordinates and transfers calls from one cell to another and maintains call continuity. Key drivers for the mobile telephone market growth include new wireless technology (3G) service availability and the replacement market for mobile phones with new capabilities such as camera phones, color displays, and increased accessory capabilities.

More at:

http://en.wikipedia.org/wiki/History_of_mobile_phones

Technologies:

The key technologies used in cellular mobile radio include cellular frequency reuse, analog cellular (1st generation), digital mobile radio (2nd generation), packet based digital radio (2 ½ generation), and wideband radio (3rd generation).

Cellular Frequency Reuse:

To conserve the limited amount of radio spectrum (maximum number of available radio channels), the cellular system concept was developed. Cellular systems allow reuse of the same channel frequencies many times within a geographic coverage area. The technique, called frequency reuse, makes it possible for a system to provide service to more customers (called system capacity) by reusing the channels that are available in a geographic area.

1st – Generation:

Analog Mobile Radio:

To allow for the conversion from analog systems to digital systems, some cellular technologies allow for the use of dual mode or multi-mode mobile telephones. These handsets are capable of operating on an analog or digital radio channel, depending on whichever is available. Most dual mode phones prefer to use digital radio channels, in the event both are available. This allows them to take advantage of the additional capacity and new features such as short messaging and digital voice quality, as well as offering greater capacity.

Regardless of the size and type of radio channels, all cellular and PCS systems allow for full duplex operation. Full duplex operation is the ability to have simultaneous communications between the caller and the called person. This means a mobile telephone must be capable of simultaneously transmitting and receiving to the radio tower. The radio channel from the mobile telephone to the radio tower is called the uplink and the radio transmission channel from the base station to the mobile telephone is called the downlink. The uplink and downlink radio channels are normally separated by 45 MHz to 80 MHz.

One of the key characteristics of cellular systems is their ability to handoff (also called handover) calls from one radio tower to another while a call is in process. Handoff is an automatic process that is a result of system monitoring and short control messages that are sent between the mobile phone and the system while the call is in progress. The control messages are so short that the customer usually cannot perceive that the handoff has occurred.

Analog cellular systems are regularly characterized by their use of analog modulation (commonly FM modulation) to transfer voice information. Ironically, almost all analog cellular systems use separate radio channels for sending system control messages. These are digital radio channels.

In early mobile radio systems, a mobile telephone scanned the limited number of available channels until it found an unused one, which allowed it to initiate a call. Because the analog cellular systems in use today have hundreds of radio channels, a mobile telephone cannot scan them all in a reasonable amount of time. To quickly direct a mobile telephone to an available channel, some of the available radio channels are dedicated as control channels. Most cellular systems use two types of radio channels, control channels and voice channels. Control channels carry only digital messages and signals, which allow the mobile telephone to retrieve system control information and compete for access.

The basic operation of an analog cellular system involves initiation of the phone when it is powered on, listening for paging messages (idle), attempting access when required and conversation (or data) mode.

When a mobile telephone is first powered on, it initializes itself by searching (scanning) a predetermined set of control channels and then tuning to the strongest one. During the initialization mode, it listens to messages on the control channel to retrieve system identification and setup information.

After initialization, the mobile telephone enters the idle mode and waits to be paged for an incoming call and senses if the user has initiated (dialed) a call (access). When a call begins to be received or initiated, the mobile telephone enters system access mode to try to access the system via a control channel. When it gains access, the control channel sends an initial voice channel designation message indicating an open voice channel. The mobile telephone then tunes to the designated voice channel and enters the conversation mode. As the mobile telephone operates on a voice channel, the system uses Frequency Modulation (FM) similar to commercial broadcast FM radio. To send control messages on the voice channel, the voice information is either replaced by a short burst (blank and burst) message or in some systems, control messages can be sent along with the audio signal.

A mobile telephone’s attempt to obtain service from a cellular system is referred to as “access”. Mobile telephones compete on the control channel to obtain access from a cellular system. Access is attempted when a command is received by the mobile telephone indicating the system needs to service that mobile telephone (such as a paging message indicating a call to be received) or as a result of a request from the user to place a call. The mobile telephone gains access by monitoring the busy/idle status of the control channel both before and during transmission of the access attempt message. If the channel is available, the mobile station begins to transmit and the base station simultaneously monitors the channel’s busy status. Transmissions must begin within a prescribed time limit after the mobile station finds that the control channel access is free, or the access attempt is stopped on the assumption that another mobile telephone has possibly gained the attention of the base station control channel receiver.

If the access attempt succeeds, the system sends out a channel assignment message commanding the mobile telephone to tune to a cellular voice channel. When a subscriber dials the mobile telephone to initiate a call, it is called “origination”. A call origination access attempt message is sent to the cellular system that contains the dialed digits, identity information along with other information. If the system allows service, the system will assign a voice channel by sending a voice channel designator message, if a voice channel is available. If the access attempt fails, the mobile telephone waits a random amount of time before trying again. The mobile station uses a random number generating algorithm internally to determine the random time to wait. The design of the system minimizes the chance of repeated collisions between different mobile stations which are both trying to access the control channel, since each one waits a different random time interval before trying again if they have already collided on their first, simultaneous attempt.

To receive calls, a mobile telephone is notified of an incoming call by a process called paging. A page is a control channel message that contains the telephone’s Mobile Identification Number (MIN) or telephone number of the desired mobile phone. When the telephone determines it has been paged, it responds automatically with a system access message that indicates its access attempt is the result of a page message and the mobile telephone begins to ring to alert the customer of an incoming telephone call. When the customer answers the call (user presses “SEND” or “TALK”), the mobile telephone transmits a service request to the system to answer the call. It does this by sending the telephone number and an electronic serial number to provide the users identity.

After a mobile telephone has been commanded to tune to a radio voice channel, it sends mostly voice or other customer information. Periodically, control messages may be sent between the base station and the mobile telephone. Control messages may command the mobile telephone to adjust its power level, change frequencies, or request a special service (such as three way calling).

To conserve battery life, a mobile phone may be permitted by the base station to only transmit when it senses the mobile telephone’s user is talking. When there is silence, the mobile telephone may stop transmitting for brief periods of time (several seconds). When the mobile telephone user begins to talk again, the transmitter is turned on again. This is called discontinuous transmission.

Analog Cellular Systems:

There are many types of analog and digital cellular systems in use throughout the world. Analog systems include AMPS, TACS, JTACS, NMT, MCS and CNET.

Advanced Mobile Phone Service (AMPS):

Advanced Mobile Phone Service (AMPS) was the original analog cellular system in the United States. It is still in widespread use and by 1997; AMPS systems were operating in over 72 countries. The AMPS system continues to evolve to allow advanced features such as increased standby time, narrowband radio channels, and anti-fraud authentication procedures.

Total Access Communication System (TACS):

The Total Access Communication System (TACS) is very similar to the US EIA-553 AMPS system. Its primary differences include changes to the radio channel frequencies, radio channel bandwidths, and data signaling rates. The TACS was introduced to the U.K. in 1985. After its introduction in the UK in 1985, over 25 countries offered TACS service. The introduction of the TACS system was very successful and the system was expanded to add more channels through what is called Extended TACS (ETACS).

The TACS system was deployed in 25 kHz radio channels, compared to the 30 kHz channels used in AMPS. This narrower radio bandwidth reduced the data speed of the signaling channel.

Nordic Mobile Telephone (NMT):

There are two Nordic Mobile Telephone (NMT) systems; NMT 450 that is a low capacity system and NMT 900 that is a high capacity system. The Nordic mobile telephone (NMT) system was developed by the telecommunications administrations of Sweden, Norway, Finland, and Denmark to create a compatible mobile telephone system in the Nordic countries. The first commercial NMT 450 cellular system was available at the end of 1981. Due to the rapid success of the initial NMT 450 system and limited capacity of the original system design, the NMT 900 system version was introduced in 1986. There are now over 40 countries that have NMT service available. Some of these countries use different frequency bands or reduced number of channels.

The NMT 450 system uses a lower frequency (450 MHz) and higher maximum transmitter power level which allows a larger cell site coverage areas while the NMT 900 system uses a higher frequency (approximately the same 900 MHz band used for TACS and GSM) and a lower maximum transmitter power which increases system capacity. NMT 450 and NMT 900 systems can co-exist which permits them to use the same switching center. This allows some NMT service providers to start offering service with an NMT 450 system and progress up to a NMT 900 system when the need arises.

Narrowband AMPS (NAMPS):

Narrowband Advanced Mobile Phone Service (NAMPS) is an analog cellular system that was commercially introduced by Motorola in late 1991 and was deployed worldwide. Like the existing AMPS technology, NAMPS uses analog FM radio for voice transmissions. The distinguishing feature of NAMPS is its use of a “narrow” 10 kHz bandwidth for radio channels, a third of the size of AMPS channels. Because more of these narrower radio channels can be installed in each cell site, NAMPS systems can serve more subscribers than AMPS systems without adding new cell sites. NAMPS also shifts some control commands to the sub-audible frequency range to facilitate simultaneous voice and data transmissions.

Japanese Mobile Cellular System (MCS):

Japan launched the world’s first commercial cellular system in 1979. Because this system had achieved great success, several different types of cellular systems have evolved in Japan. These include the MCS-L1, MCSL2, JTACS and NTACS systems. The MCS-L1 was the first cellular system in Japan, which was developed and operated by NTT. The system operates in the 800 MHz band. The channel bandwidth is 25 kHz and the signaling is at 300 bps. The control channels are simulcast from all base stations in the local area. This limits the maximum capacity of the MCS-L1 system.

Because the MCS-L1 system could only serve a limited number of customers, the MCS-L2 system was developed. It uses the same frequency bands as the MCS-L1 system. The radio channel bandwidth was reduced from 25 kHz to 12.5 kHz with 6.25 kHz interleaving. This gives the MCS-L2 system 2,400 channels. The control channels transfer information at 2,400 bps and the voice channels can use either in-band (blank and burst) signaling at 2,400 bps or sub-band digital audio signaling at 150 bps. MCS-L2 mobile telephones have diversity reception (similar to diversity receive used in base stations). While this increases the cost and size of the mobile telephones, it also increases the performance and range of the cellular system.

CNET:

CNET is an analog cellular system that is used in Germany, Portugal, and South Africa. The first CNET system started operation in Germany in 1985. The primary objective of the CNET system was to bridge the gap of cellular systems in Germany until the digital European system could be introduced

MATS-E:

The MATS-E system is used in France and Kuwait. The MATS-E system combines many of the features used in different cellular systems. MATS-E uses the standard European mobile telephone frequency bands.

More at:

http://tinyurl.com/6e4hzp
http://en.wikipedia.org/wiki/Advanced_Mobile_Phone_System

2nd - Generation:

Digital Mobile Radio:

There are two basic types of systems; analog and digital. Analog systems commonly use FM modulation to transfer voice information and digital systems use some form of phase modulation to transfer digital voice and data information. Although analog systems are capable of providing many of the services that digital systems offer, digital systems offer added flexibility as many of the features can be created by software changes.

Digital cellular systems use two key types of communication channels, control channels and voice channels. A control channel on a digital system is usually one of the sub-channels on the radio channel. This allows digital systems to combine a control channel and one or more voice channels on a single radio channel. The portions of the radio channel that is dedicated as a control channel carries only digital messages and signals that allow the mobile telephone to retrieve system control information and compete for access. The other sub-channels on the radio channel carry voice or data information.

The basic operation of a digital cellular system involves initiation of the phone when it is powered on, listening for paging messages (idle), attempting access when required and conversation (or data) mode.

When a digital mobile telephone is first powered on, it initializes itself by searching (scanning) a predetermined set of control channels and then tuning to the strongest one. During the initialization mode, it listens to messages on the control channel to retrieve system identification and setup information. Compared to analog systems, digital systems have more communication and control channels. This can result in the mobile phone taking more time to search for control channels. To quickly direct a mobile telephone to an available control channel, digital systems use several processes to help a mobile telephone to find an available control channel. These include having the phone memorize its last successful control channel location, a table of likely control channel locations and a mechanism for pointing to the location of a control channel on any of the operating channels.

After a digital mobile telephone has initialized, it enters an idle mode where it waits to be paged for an incoming call or for the user to initiate a call. When a call begins to be received or initiated, the mobile telephone enters system access mode to try to access the system via a control channel. When it gains access, the control channel sends a digital traffic channel designation message indicating an open communications channel. This channel may be on a different time slot on the same frequency or to a time slot on a different frequency. The digital mobile telephone then tunes to the designated communications channel and enters the conversation mode. As the mobile telephone operates on a digital voice channel, the digital system commonly uses some form of phase modulation (PM) to send and receive digital information.

A mobile telephone’s attempt to obtain service from a cellular system is referred to as “access”. Digital mobile telephones compete on the control channel to obtain access from a cellular system. Access is attempted when a command is received by the mobile telephone indicating the system needs to service that mobile telephone (such as a paging message indicating a call to be received) or as a result of a request from the user to place a call. Digital mobile telephones usually have the ability to validate their identities more securely during access than analog mobile telephones. This is made possible by a process called authentication. Authentication processes share secret data between the digital mobile phone and the cellular system.

If the authentication is successful, the system sends out a channel assignment message commanding the mobile telephone to change to a new communication channel and conversation can begin.

After a mobile telephone has been commanded to tune to a radio voice channel, it sends digitized voice or other customer data. Periodically, control messages may be sent between the base station and the mobile telephone. Control messages may command the mobile telephone to adjust its power level, change frequencies, or request a special service (such as three way calling). To send control messages while the digital mobile phone is transferring digital voice, the voice information is either replaced by a short burst (called blank and burst or fast signaling), or else control messages can be sent along with the digitized voice signals (called slow signaling).

Most digital telephones automatically conserve battery life as they transmit only for short periods of time (bursts). In addition to savings through digital burst transmission, digital phones ordinarily have the capability of discontinuous transmission that allows the inhibiting of the transmitter during periods of user silence. When the mobile telephone user begins to talk again, the transmitter is turned on again. The combination of the power savings allows some digital mobile telephones to have 2 to 5 times the battery life in the transmit mode.

Digital technology increases system efficiency by voice digitization, speech compression (coding), channel coding, and the use of spectrally efficient radio signal modulation.

Standard voice digitization in the Public Switched Telephone Network (PSTN) produces a data rate of 64 kilobits per second (kbps). Because transmitting a digital signal via radio requires about 1 Hz of radio bandwidth for each bps, an uncompressed digital voice signal would require more than 64 kHz of radio bandwidth. Without compression, this bandwidth would make digital transmission less efficient than analog FM cellular, which uses only 25-30 kHz for a single voice channel. Therefore, digital systems compress speech information using a voice coder or Vocoder. Speech coding removes redundancy in the digital signal and attempts to ignore data patterns that are not characteristic of the human voice. The result is a digital signal that represents the voice audio frequency spectrum content, not a waveform.

A Vocoder characterizes the input signal. It looks up codes in a code book table that represents various digital patterns to choose the pattern that comes closest to the input digitized signal. The amount of digitized speech compression used in digital cellular systems varies. For the IS-136 TDMA system, the compression is 8:1. For CDMA, the compression varies from 8:1 to 64:1 depending on speech activity. GSM systems compress the voice by 5:1.

Digital Cellular Systems:

The types of 2nd generation digital cellular systems include GSM, IS-136 TDMA and CDMA.

Global System for Mobile Communication (GSM):

The Global System for Mobile Communications (GSM) system is a global digital radio system that uses Time Division Multiple Access (TDMA) technology. GSM is a digital cellular technology that was initially created to provide a single-standard pan-European cellular system. GSM began development in 1982, and the first commercial GSM digital cellular system was activated in 1991. GSM technology has evolved to be used in a variety of systems and frequencies (900 MHz, 1800 MHz and 1900 MHz) including Personal Communications Services (PCS) in North America and Personal Communications Network (PCN) systems throughout the world. By the middle of 2003, 510 networks in 200 countries offered GSM service.

The GSM system is a digital-only system and was not designed to be backward-compatible with the established analog systems. The GSM radio band is shared temporarily with analog cellular systems in some European nations.

When communicating in a GSM system, users can operate on the same radio channel simultaneously by sharing time slots. The GSM cellular system allows 8 mobile telephones to share a single 200 kHz bandwidth radio carrier waveform for voice or data communications. To allow duplex operation, GSM voice communication is conducted on two 200 kHz wide carrier frequency waveforms.

The GSM system has several types of control channels that carry system and paging information, and coordinates access like the control channels on analog systems. The GSM digital control channels have many more capabilities than analog control channels such as broadcast message paging, extended sleep mode, and others. Because the GSM control channels use only a portion (one or more slots), they typically co-exist on a single radio channel with other time slots that are used for voice communication.

A GSM carrier transmits at a bit rate of 270 kbps, but a single GSM digital radio channel or time slot is capable of transferring only 1/8th of that, about 33 kbps of information (actually less than that, due to the use of some bit time for non-information purposes such as synchronization bits).

North American TDMA (IS-136 TDMA):

The North American TDMA system (IS-136) is a digital system that uses TDMA access technology. It evolved from the IS-54 specification that was developed in North America in the late 1980’s to allow the gradual evolution of the AMPS system to digital service. The IS-136 system is sometimes referred to as Digital AMPS (DAMPS) or North American digital cellular (NADC).

In 1988, the Cellular Telecommunications Industry Association created a development guideline for the next generation of cellular technology for North America. This guideline was called the User Performance Requirements (UPR) and the Telecommunications Industry Association (TIA) used this guideline to create a TDMA digital standard, called IS-54. This digital specification evolved from the original EIA-553 AMPS specification. The first revision of the IS-54 specification (Rev 0) identified the basic parameters (e.g. time slot structure, type of radio channel modulation, and message formats) needed to begin designing TDMA cellular equipment. There have been several enhancements to IS-54 since its introduction and in 1995; IS-54 was incorporated as part of the IS-136 specification.

A primary feature of the IS-136 systems is their ease of adaptation to the existing AMPS system. Much of this adaptability is due to the fact that IS- 136 radio channels retain the same 30 kHz bandwidth as AMPS system channels. Most base stations can therefore replace TDMA radio units in locations previously occupied by AMPS radio units. Another factor in favor of adaptability is that new dual mode mobile telephones were developed to operate on either IS-136 digital traffic (voice and data) channels or the existing AMPS radio channels as requested in the CTIA UPR document. This allows a single mobile telephone to operate on any AMPS system and use the IS-136 system whenever it is available.

The IS-136 specification concentrates on features that were not present in the earlier IS-54 TDMA system. These include longer standby time, short message service functions, and support for small private or residential systems that can coexist with the public systems. In addition, IS-136 defines a digital control channel to accompany the Digital Traffic Channel (DTC). The digital control channel allows a mobile telephone to operate in a single digital-only mode. Revision A of the IS-136 specification now supports operation in the 800 MHz range for the existing AMPS and DAMPS systems as well as the newly allocated 1900MHz bands for PCS systems. This permits dual band, dual mode phones (800 MHz and 1900 MHz for AMPS and DAMPS). The primary difference between the two bands is that mobile telephones cannot transmit using analog signals at 1900MHz. The IS-136 cellular system allows for mobile telephones to use either 30 kHz analog (AMPS) or 30 kHz digital (TDMA) radio channels. The IS-136 TDMA radio channel allows multiple mobile telephones to share the same radio frequency channel by time-sharing. All IS-136 TDMA digital radio channels are divided into frames with 6 time slots. The time slots used for the correspondingly numbered forward and reverse channels are time-related so that the mobile telephone does not simultaneously transmit and receive.

The RF power levels for the mobile phones are almost exactly the same as for the AMPS telephones. The primary difference in the power levels is a reduction in minimum power level that mobile telephones can be instructed to reduce to. This allows for very small cell coverage areas, typically the size of cells that would be used for wireless office or home cordless systems.

Extended TDMA (E-TDMA):

Extended TDMA was developed by Hughes Network Systems in 1990 as an extension to the existing IS-136 TDMA industry standard. ETDMA uses the existing TDMA radio channel bandwidth and channel structure and its receivers are tri-mode as they can operate in AMPS, TDMA, or ETDMA modes. While a TDMA system assigns a mobile telephone fixed time slot numbers for each call, ETDMA dynamically assigned time slots on an as needed basis. The ETDMA system contains a half-rate speech coder (4 kb/s) that reduces the number of information bits that must be transmitted and received each second. This makes use of voice silence periods to inhibit slot transmission so other users may share the transmit slot. The overall benefit is that more users can share the same radio channel equipment and improved radio communications performance. The combination of a low bit rate speech coder, voice activity detection, and interference averaging increases the radio channel efficiency to beyond 10 times the existing AMPS capacity.

ETDMA radio channels are structured into the same frames and slots structures as the standard IS-54 radio channels. Some or all of the time slots on all of the radio channels are shared for ETDMA communication, which is similar to IS-54 and IS-136 radio channels, or else slots can be shared on different frequencies. When a Mobile telephone is operating in extended mode, the ETDMA system must continually coordinate time slot and frequency channel assignments. The ETDMA system performs this by using a time slot control system. On an ETDMA capable radio channel some of the time slots are dedicated as control slots on an as needed basis. ETDMA systems can assign an AMPS channel, a TDMA full-rate or half-rate channel, or an ETDMA channel. The existing 30 kHz AMPS control channels are used to assign analog voice and digital traffic channels.

Integrated Dispatch Enhanced Network (iDEN):

Integrated Dispatch Enhanced Network (iDEN) a digital radio system that provides for voice, dispatch and data services. iDEN was formerly called Motorola Integrated Radio System (MIRS). iDEN was deployed in 1996 for enhanced specialized mobile radio (E-SMR) service. The iDEN system radio channel bandwidth is 25 kHz and it is divided into frames that have 6 times slots per frame. The iDEN system allows 6 mobile radios to simultaneously share a single radio channel for dispatch voice quality and up to 3 mobile radios can simultaneously share a radio channel for cellular like voice quality.

Code Division Multiple Access (IS-95 CDMA):

Code Division Multiple Access (CDMA) system (IS 95) is a digital cellular system that uses CDMA access technology. IS-95 technology was initially developed by Qualcomm in the late 1980’s. CDMA cellular service began testing in the United States in San Diego, California during 1991. In 1995, IS-95 CDMA commercial service began in Hong Kong and now many CDMA systems are operating throughout the world, including a 1.9 GHz all-digital system in the USA that has been operating since November 1996.

Spread spectrum radio technology has been used for many years in military applications. CDMA is a particular form of spread spectrum radio technology. In 1989, CDMA spread spectrum technology was presented to the industry standards committee but it did not meet with immediate approval. The standards committee had just resolved a two-year debate between TDMA and FDMA and was not eager to consider another access technology.

The IS-95 CDMA system allows for voice or data communications on either a 30 kHz AMPS radio channel (when used on the 800 MHz cellular band) or a new 1.25 MHz CDMA radio channel. The IS-95 CDMA radio channel allows multiple mobile telephones to communicate on the same frequency at the same time by special coding of their radio signals.

The CDMA system is compatible with the established access technology, and it allows analog (EIA-553) and dual mode (IS-95) subscribers to use the same analog control channels. Some of the voice channels are replaced by CDMA digital transmissions, allowing several users to be multiplexed (shared) on a single RF channel. As with other digital technologies, CDMA produces capacity expansion by allowing multiple users to share a single digital RF channel.

CDMA systems use a maximum of 64 coded (logical) traffic channels, but they cannot always use all of these. To obtain a maximum of 64 communication channels for each CDMA radio channel, the average data rate for each user should approximate 3 kbps. If the average data rate is higher, less than 64 traffic channels can be used. CDMA systems can vary the data rate for each user dependent on voice activity (variable rate speech coding), thereby decreasing the average number of bits per user to about 3.8 kbps. Varying the data rate according to user requirement allows more users to share the radio channel, but with slightly reduced voice quality. This is called soft capacity limit.

Japanese Personal Digital Cellular (PDC):

The PDC system is a TDMA technology with a radio interface that is very similar to IS-136, in that it has six timeslots and an almost identical data rate, and a core network architecture that is very similar to GSM. PDC operates in both the 900 MHz and 1,400 MHz regions of the radio spectrum.

More at:
http://en.wikipedia.org/wiki/2G
http://www.arcelect.com/2g-3g_cellular_wireless.htm
http://en.wikipedia.org/wiki/GSM
http://en.wikipedia.org/wiki/CDMA

Generation 2.5:

Packet Based Digital Cellular:

Packet Based Cellular (commonly called - generation 2.5, or 2.5G) are 2nd Generation cellular technologies that have been enhanced to provide for advanced communication applications. Packet based digital cellular systems help the industry transition from one capability to a much more advanced capability. In cellular telecommunications, 2.5G systems used improved digital radio technology to increase their data transmission rates and new packet based technology to increase the system efficiency for data users.

Upgraded Digital Cellular System:

The types of upgraded 2nd generation digital cellular systems (generation 2.5) include GPRS, EDGE, and CDMA2000, 1xRTT. General Packet Radio Service (GPRS): General Packet Radio Service (GPRS) is a portion of the GSM specification that allows packet radio service on the GSM system. The GPRS system adds (defines) new packet channels and switching nodes within the GSM system. The GPRS system provides for theoretical data transmission rates up to 172 kbps.

Enhanced Data Rates for Global Evolution (EDGE):

Some also refer it to as generation 2.75 technology. Enhanced Data Rates for global Evolution (EDGE) is an evolved version of the global system for mobile (GSM) radio channel that uses new phase modulation and packet transmission to provide for advanced high-speed data services. The EDGE system uses 8 levels Phase Shift Keying (8PSK) to allow one symbol change to represent 3 bits of information. This is 3 times the amount of information that is transferred by a standard 2 level Gaussian Minimum Shift Keying (GMSK) signal used by the first generation of GSM system. This results in a radio channel data transmission rate of 604.8 kbps and a net maximum delivered theoretical data transmission rate of 384 kbps. The advanced packet transmission control system allows for constantly varying data transmission rates in either direction between mobile radios.

CDMA2000, 1xRTT:

CDMA2000 is a 3G standard that allows operators to evolve from their existing IS-95 networks to offer 3G services. The original CDMA2000 proposal contained two distinct evolutionary phases, the first known as 1xRTT used the same 1.25 MHz channels as IS-95 but delivered increased capacity and data rates compared to IS-95. The second phase was known as 3xRTT that uses three times the spectrum of IS-95, that is 3.75 MHz. The 3xRTT concept would deliver data rates up to 2 Mbps, a requirement for any 3G technologies. However recent evolutions of 1xRTT are offering data rates in excess of this and therefore it is unlikely that 3xRTT is required. By the middle of 2003 there were a total of 60 commercial 1xRTT networks offering service.

Evolution Data Only (1xEVDO):

The evolution of existing systems for data only (1xEVDO) is an evolved version of the CDMA2000 1xRTT system. The 1xEVDO system uses the same 1.25 MHz radio channel bandwidth as the existing IS-95 system that provides for multiple voice channels and medium rate data services. The 1xEVDO version changes the modulation technology to allow for data transmission rates up to 2.5 Mbps. The 1xEVDO system has an upgraded packet data transmission control system that allows for bursty data transmission rather than for more continuous voice data transmission.

Evolution Data and Voice (1xEVDV):

The evolution of existing systems for data and voice (1xEVDV) is an evolved version of the CDMA2000 1xRTT system that can be used for data and voice service. The 1xEVDV system provides for both voice and high-speed data transmission services in the same 1.25 MHz radio channel bandwidth as the existing IS-95 system. The 1xEVDV Vision allows for a maximum data transmission rate of approximately 2.7 Mbps.

More at:

http://en.wikipedia.org/wiki/GPRS
http://en.wikipedia.org/wiki/GPRS_Core_Network
http://en.wikipedia.org/wiki/2.5G

3rd Generation:

Wideband Digital Cellular:

Wideband Digital Cellular (commonly called 3rd generation) is cellular technology that uses wideband digital radio technology as compared to 2nd generation narrowband digital radio. A wideband digital cellular system that permits very high- speed data transmission rates through the use of relatively wide radio channels. In this system, the radio channels are much wider many tens of times wider than 2nd generation radio channels. This allows wideband digital cellular systems to send high-speed data to communication devices. This system also uses communication servers to help to manage multimedia communication sessions. Aside from the use of wideband radio channels and enhanced packet data communication, the 3rd generation systems typically use the same voice network switching systems (such as the MSC) as 2nd generation mobile communications systems.

Wideband Digital Cellular Systems:

The 3rd generation wireless requirements are defined in the International Mobile Telecommunications “IMT-2000” project developed by the International Telecommunication Union (ITU). The IMT-2000 project that defined requirements for high-speed data transmission, Internet Protocol (IP)-based services, global roaming, and multimedia communications. After many communication proposals were reviewed, two global systems are emerging; wideband code division multiple access (WCDMA) and CDMA2000.

More at:

http://www.itu.int/osg/imt-project/
http://www.itu.int/osg/imt-project/docs/What_is_IMT2000-2.pdf

Wideband Code Division Multiple Access (WCDMA):

WCDMA is a 3rd generation digital cellular system that uses radio channels that have a wider bandwidth than 2nd generation digital cellular systems such as GSM or IS-95 CDMA. WCDMA is normally deployed in a 5 MHz channel plan.

The Third Generation Partnership Project (3GPP) oversees the creation of industry standards for the 3rd generation of mobile wireless communication systems (WCDMA). The key members of the 3GPP include standards agencies from Japan, Europe, Korea, China and the United States. The 3GPP technology, also known as the Universal Mobile Telecommunications System (UMTS), is based on an evolved GSM core network that contains 2.5G elements, namely GPRS switching nodes. This concept allows a GSM network operator to migrate to WCDMA by adding the necessary 3G radio elements to their existing network, thus creating ‘islands’ of 3G coverage when the networks first launch.

A large number of GSM operators have secured spectrum for WCDMA and many network launches are imminent, with live networks presently in Japan, the United Kingdom and Italy.

Code Division Multiple Access 2000 (CDMA2000):

CDMA2000 is a family of standards that represent an evolution from the IS- 95 code division multiple access (CDMA) system that offer enhanced packet transmission protocols to provide for advanced high-speed data services. The CDMA2000 technologies operate in the same 1.25 MHz radio channels as used by IS-95 and offer backward compatibility with IS-95. The CDMA2000 system is overseen by the Third Generation Partnership Project 2 (3GPP2). The 3GPP2 is a standards setting project that is focused on developing global specifications for 3rd generation systems that use ANSI/TIA/EIA-41 Cellular Radio Intersystem Signaling.

Time Division Synchronous CDMA (TD-SCDMA):

On a global basis it likely that WCDMA and CDMA2000TM will dominate the 3G market, however in China there is growing support for a homegrown standard known as Time Division Synchronous CDMA (TD-SCDMA). TDSCDMA offers voice services and data services, both circuit-switched and packet-switched, at rates up to 2 Mbps. It uses a Time Division Duplex (TDD) technique in which transmit and receive signals are sent on the same frequency but at different times. The timeslots on the radio carrier can either be allocated symmetrically for services such as speech or asymmetrically for data services where the bit rates in the two directions of transmission may differ significantly.

More at:

http://en.wikipedia.org/wiki/W-CDMA
http://www.ericsson.com/technology/tech_articles/WCDMA.shtml
http://en.wikipedia.org/wiki/CDMA2000
http://www.cdg.org/technology/3g.asp
http://tinyurl.com/6mqygd

Future Enhancements:

There are likely to be many future enhancements to mobile radio. Some of the key innovations include software defined radios, spatial division multiple access (SDMA), and 4th generation mobile telephones.

Software Defined Radios:

Software defined radios are transceiver devices that use digital signal processing to create and decode radio messages. Because they use digital signal processing for almost all functions, it is possible to change access technologies and radio transmission characteristics through software changes. Thus it may be possible in the future for a handset or other terminal to download the necessary parameters of a network as the mobile moves from one technology to another.

Spatial Division Multiple Access (SDMA):

Spatial Division Multiple Access (SDMA) is a technology that increases the quality and capacity of wireless communications systems. Using advanced algorithms and adaptive digital signal processing; Base Stations equipped with multiple antennas can more actively reject interference and use spectral resources more efficiently. This would allow for larger cells with less radiated energy, greater sensitivity for portable cellular phones, and greater network capacity.

Fourth Generation (4G) Networks:

Even before 3G networks are fully launched and utilized, various study groups are considering the shape of the next generation of cellular technology, so called 4G. There is no single global vision for 4G as yet but the next generation of network is likely to be all IP-based, offer data rates up to 100 Mbps and support true global mobility. One route towards this vision is the convergence of technologies such as 3G cellular and Wireless LANs (WLANs).

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