Even though many mobile and wireless devices are available ,there will be many more in future.There is no precise classification of these devices like the shape,size ,body.etc..the list of followin device according to there grades..like sensors,embedded controlers,pagers,etc..
SENSORS- it is used to transmit the state information,one example would be like the door sensors i.e it senses a person standing near the door and the door opens .If the person is inside the door closes down automatically ,thus it is provided along wit intelligent systems.
PAGER- it was used few years back,but was a very important device as the messages could b easily send .It was only when mobiles were discovered and pagers had no longer market exixtance.
Saturday, December 29, 2007
Monday, December 17, 2007
SECURITY
GSM was designed with a moderate level of security. The system was designed to authenticate the subscriber using a SHARED and challenge response. Communications between the subscriber and the base station can be encrypted. The development of umts introduces an optional usim, that uses a longer authentication key to give greater security, as well as mutually authenticating the network and the user - whereas GSM only authenticated the user to the network (and not vice versa). The security model therefore offers confidentiality and authentication, but limited authorization capabilities, and no non repudation.
GSM uses several cryptographic algorithms for security. The a-5 and a-2,2 are used for ensuring over-the-air voice privacy. A5/1 was developed first and is a stronger algorithm used within Europe and the United States; A5/2 is weaker and used in other countries. A large security advantage of GSM over earlier systems is that the Key, the crypto variable stored on the sim card that is the key to any GSM ciphering algorithm, is never sent over the air interface. Serious weaknesses have been found in both algorithms, and it is possible to break A5/2 in real-time in a cipher txt. The system supports multiple algorithms so operators may replace that cipher with a stronger one.
GSM uses several cryptographic algorithms for security. The a-5 and a-2,2 are used for ensuring over-the-air voice privacy. A5/1 was developed first and is a stronger algorithm used within Europe and the United States; A5/2 is weaker and used in other countries. A large security advantage of GSM over earlier systems is that the Key, the crypto variable stored on the sim card that is the key to any GSM ciphering algorithm, is never sent over the air interface. Serious weaknesses have been found in both algorithms, and it is possible to break A5/2 in real-time in a cipher txt. The system supports multiple algorithms so operators may replace that cipher with a stronger one.
HISTORY...
In 1982, the (CEPT) created the Groupe Spécial Mobile (GSM) to develop a standard for a mobile telephone system that could be used across Europe. In 1987, a was signed by 13 countries to develop a common cellular telephone system across Europe.
In 1989, GSM responsibility was transferred to the (ETSI) and phase I of the GSM specifications were published in 1990. The first GSM network was launched in 1991 , with joint technical infrastructure maintenance from Ericsson. By the end of 1993, over a million subscribers were using GSM phone networks being operated by 70 carriers across 48 countries.thus the use is precisely increasing!
In 1989, GSM responsibility was transferred to the (ETSI) and phase I of the GSM specifications were published in 1990. The first GSM network was launched in 1991 , with joint technical infrastructure maintenance from Ericsson. By the end of 1993, over a million subscribers were using GSM phone networks being operated by 70 carriers across 48 countries.thus the use is precisely increasing!
MOBILE COMMUNICATIONS
GSM
Global System for Mobile communications (GSM: originally from Groupe Spécial Mobile) is the most popular standard for Mobile phones in the world. Its promoter, the GSMASSOCIATION, estimates that 82% of the global mobile market uses the standard (1). GSM is used by over 2 BILLION people across more than 212 countries and territories. Its ubiquity makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world. GSM differs from its predecessors in that both signaling and speech channels are digital call, and so is considered a second generation (2g) mobile phone system. This has also meant that data communication were built into the system using the 3rd generation.
NOTE
I m going to put question answeres releated to mobile - communications/computing in details in this blog ,all the areas will be covered acordin to syllabus.
Global System for Mobile communications (GSM: originally from Groupe Spécial Mobile) is the most popular standard for Mobile phones in the world. Its promoter, the GSMASSOCIATION, estimates that 82% of the global mobile market uses the standard (1). GSM is used by over 2 BILLION people across more than 212 countries and territories. Its ubiquity makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world. GSM differs from its predecessors in that both signaling and speech channels are digital call, and so is considered a second generation (2g) mobile phone system. This has also meant that data communication were built into the system using the 3rd generation.
NOTE
I m going to put question answeres releated to mobile - communications/computing in details in this blog ,all the areas will be covered acordin to syllabus.
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