Mobile is a vital instrument for our life. Now we can easily communicate with another although he stay another part of the word. More over we can not imagine our buisness development without mobile phone. 
Normal Burst StructuresGSM is one of the feature of mobile phone. GSM mobile is more comfortable then another meobile phone. Majority people of the world are using GSM mobile phone.This figure shows the field structures of the normal burst used in the GSM system. This diagram shows that the field structure is different for the normal burst, synchronization burst, and the frequency correction bursts. The fields transmitted during the normal burst include initial tail bits (ramp-up time), training sequence, flag bits, user data bits, final tail bits, and guard period. This diagram shows that the first 3 bits of the time slot are dedicated to the gradual increase of transmitter power level (ramp-up). For the normal burst, this is followed by the information (user data) bits. The flag bits indicate if the normal burst has been replaced with FACCH signaling information. This diagram shows that some of the bits in the center of the burst are used as training bits (to allow equalizer training). At the end of the transmitted burst there are tail bits (for error protection) and 3 guard period bits that are used during the gradual reduction of the RF transmitter signal (ramp-down).
Japan's first commercial mobile phone service was launched by NTT in 1978. By November 2007, the total number of mobile phone subscriptions in the world had reached 3.3 billion, or half of the human population (although some users have multiple subscriptions, or inactive subscriptions), which also makes the mobile phone the most widely spread technology and the most common electronic device in the world.[3]
The first mobile phone to enable internet connectivity and wireless email, the Nokia Communicator, was released in 1996, creating a new category of multi-use devices called smartphones. In 1999 the first mobile internet service was launched by NTT DoCoMo in Japan under the i-Mode service. By 2007 over 798 million people around the world accessed the internet or equivalent mobile internet services such as WAP and i-Mode at least occasionally using a mobile phone rather than a personal computer.
As of 2007, more than a billion mobile phones are sold each year, including over 100,000 smart-phones.[4]
[edit] Cellular systems
See also: Cellular frequencies
Mobile phone tower
Mobile phones send and receive radio signals with any number of cell site base stations fitted with microwave antennas. These sites are usually mounted on a tower, pole or building, located throughout populated areas, then connected to a cabled communication
[edit] Usage
[edit] By civilians
This Railfone found on some Amtrak trains in North America uses cellular technology.
See also: List of mobile network operators
An increasing number of countries, particularly in Europe, now have more mobile phones than people. According to the figures from Eurostat, the European Union's in-house statistical office, Luxembourg had the highest mobile phone penetration rate at 158 mobile subscriptions per 100 people, closely followed by Lithuania and Italy.[5] In Hong Kong the penetration rate reached 139.8% of the population in July 2007.[6] Over 50 countries have mobile phone subscription penetration rates higher than that of the population and the Western European average penetration rate was 110% in 2007 (source Informa 2007). Canada currently has the lowest rates of mobile phone penetrations in the industrialised world at 58%.
There are over five hundred million active mobile phone accounts in China, as of 2007, but the total penetration rate there still stands below 50%.[7] The total number of mobile phone subscribers in the world was estimated at 2.14 billion in 2005.[8] The subscriber count reached 2.7 billion by end of 2006 according to Informa[citation needed], and 3.3 billion by November, 2007[3], thus reaching an equivalent of over half the planet's population. Around 80% of the world's population has access to mobile phone coverage, as of 2006. This figure is expected to increase to 90% by the year 2010.[9]
In some developing countries with little "landline" telephone infrastructure, mobile phone use has quadrupled in the last decade.[10] The rise of mobile phone technology in developing countries is often cited as an example of the leapfrog effect. Many remote regions in the third world went from having no telecommunications infrastructure to having satellite based communications systems. At present, Africa has the largest growth rate of cellular subscribers in the world,[11] its markets expanding nearly twice as fast as Asian markets.[12] The availability of prepaid or 'pay-as-you-go' services, where the subscriber is not committed to a long term contract, has helped fuel this growth in Africa as well as in other continents.
On a numerical basis, India is the largest growth market, adding about 6 million mobile phones every month.[13] With 256.55 million total landline and mobile phones, market penetration in the country is still low at 22.52%. India expects to reach 500 million subscribers by the end of 2010. Simultaneously, landline phone ownership is decreasing gradually and accounts for approximately 40 million connections.
There are three major technical standards for the current generation of mobile phones and networks, and two major standards for the next generation 3G phones and networks. All European and African countries and many Asian countries have adopted a single system, GSM, which is the only technology available on all continents and in most countries and covers over 74% of all subscribers on mobile networks. In many countries, such as the United States, Australia, Brazil, Canada, Costa Rica, India,, South Korea, and Vietnam, GSM co-exists with other internationally adopted standards such as CDMA and TDMA, as well as national standards such as iDEN in the USA and PDC in Japan. Over the past five years several dozen mobile operators (carriers) have abandoned networks on TDMA and CDMA technologies, switching over to GSM.
With third generation (3G) networks, which are also known as IMT-2000 networks, about three out of four networks are on the W-CDMA (also known as UMTS) standard, usually seen as the natural evolution path for GSM and TDMA networks. One in four 3G networks is on the CDMA2000 1x EV-DO technology. Some analysts count a previous stage in CDMA evolution, CDMA2000 1x RTT, as a 3G technology whereas most standardization experts count only CDMA2000 1x EV-DO as a true 3G technology. Because of this difference in interpreting what is 3G, there is a wide variety in subscriber counts. As of June 2007, on the narrow definition there are 200 million subscribers on 3G networks. By using the more broad definition, the total subscriber count of 3G phone users is 475 million
The first mobile phone to enable internet connectivity and wireless email, the Nokia Communicator, was released in 1996, creating a new category of multi-use devices called smartphones. In 1999 the first mobile internet service was launched by NTT DoCoMo in Japan under the i-Mode service. By 2007 over 798 million people around the world accessed the internet or equivalent mobile internet services such as WAP and i-Mode at least occasionally using a mobile phone rather than a personal computer.
As of 2007, more than a billion mobile phones are sold each year, including over 100,000 smart-phones.[4]
[edit] Cellular systems
See also: Cellular frequencies
Mobile phone tower
Mobile phones send and receive radio signals with any number of cell site base stations fitted with microwave antennas. These sites are usually mounted on a tower, pole or building, located throughout populated areas, then connected to a cabled communication
[edit] Usage
[edit] By civilians
This Railfone found on some Amtrak trains in North America uses cellular technology.
See also: List of mobile network operators
An increasing number of countries, particularly in Europe, now have more mobile phones than people. According to the figures from Eurostat, the European Union's in-house statistical office, Luxembourg had the highest mobile phone penetration rate at 158 mobile subscriptions per 100 people, closely followed by Lithuania and Italy.[5] In Hong Kong the penetration rate reached 139.8% of the population in July 2007.[6] Over 50 countries have mobile phone subscription penetration rates higher than that of the population and the Western European average penetration rate was 110% in 2007 (source Informa 2007). Canada currently has the lowest rates of mobile phone penetrations in the industrialised world at 58%.
There are over five hundred million active mobile phone accounts in China, as of 2007, but the total penetration rate there still stands below 50%.[7] The total number of mobile phone subscribers in the world was estimated at 2.14 billion in 2005.[8] The subscriber count reached 2.7 billion by end of 2006 according to Informa[citation needed], and 3.3 billion by November, 2007[3], thus reaching an equivalent of over half the planet's population. Around 80% of the world's population has access to mobile phone coverage, as of 2006. This figure is expected to increase to 90% by the year 2010.[9]
In some developing countries with little "landline" telephone infrastructure, mobile phone use has quadrupled in the last decade.[10] The rise of mobile phone technology in developing countries is often cited as an example of the leapfrog effect. Many remote regions in the third world went from having no telecommunications infrastructure to having satellite based communications systems. At present, Africa has the largest growth rate of cellular subscribers in the world,[11] its markets expanding nearly twice as fast as Asian markets.[12] The availability of prepaid or 'pay-as-you-go' services, where the subscriber is not committed to a long term contract, has helped fuel this growth in Africa as well as in other continents.
On a numerical basis, India is the largest growth market, adding about 6 million mobile phones every month.[13] With 256.55 million total landline and mobile phones, market penetration in the country is still low at 22.52%. India expects to reach 500 million subscribers by the end of 2010. Simultaneously, landline phone ownership is decreasing gradually and accounts for approximately 40 million connections.
There are three major technical standards for the current generation of mobile phones and networks, and two major standards for the next generation 3G phones and networks. All European and African countries and many Asian countries have adopted a single system, GSM, which is the only technology available on all continents and in most countries and covers over 74% of all subscribers on mobile networks. In many countries, such as the United States, Australia, Brazil, Canada, Costa Rica, India,, South Korea, and Vietnam, GSM co-exists with other internationally adopted standards such as CDMA and TDMA, as well as national standards such as iDEN in the USA and PDC in Japan. Over the past five years several dozen mobile operators (carriers) have abandoned networks on TDMA and CDMA technologies, switching over to GSM.
With third generation (3G) networks, which are also known as IMT-2000 networks, about three out of four networks are on the W-CDMA (also known as UMTS) standard, usually seen as the natural evolution path for GSM and TDMA networks. One in four 3G networks is on the CDMA2000 1x EV-DO technology. Some analysts count a previous stage in CDMA evolution, CDMA2000 1x RTT, as a 3G technology whereas most standardization experts count only CDMA2000 1x EV-DO as a true 3G technology. Because of this difference in interpreting what is 3G, there is a wide variety in subscriber counts. As of June 2007, on the narrow definition there are 200 million subscribers on 3G networks. By using the more broad definition, the total subscriber count of 3G phone users is 475 million
কোন মন্তব্য নেই:
একটি মন্তব্য পোস্ট করুন