توضیحات

 این یک مونوگراف تکمیل بوده که دارای پرپوزل هم میباشد شما میتوانید با پیام گذاشتن در وتسپ ما آن را دریافت کنید

وتسپ:۰۷۹۹۱۱۸۸۳۱

مونوگراف به صورت تضمینی بوده که نیاز به تغیرات ندارد و قبلا دفاع و ارایه شده است

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Introduction

Cell phones can provide an inexpensive means of communications, particularly cell phones with a two-way radio function. They provide in a single unit both a two-way radio and the ability to call the police directly when needed, as well as managers.

Cell phones have limits, however. Before deciding on using a cell phone as a primary means of communication, it is important to conduct a test with the type of cell phone planned for use in every dark recess of the building, parking structure, stairwell, restroom, storage room, and throughout the entire facility. Otherwise, you may discover a dead spot in exactly the place where the worst possible emergency is occurring, exactly when it occurs. Cell phones are particularly valuable for patrol officers in vehicles because of their wide geographical reach, allowing the officer to be reached both on and off the property. Mobile phone data, like GPS data, is passively collected. However, mobile phone datasets have distinct characteristics compared to GPS datasets. Mobile phone data contains location information at much coarser temporal resolution than GPS data. As reviewed by Chen, Ma, Susilo, Liu, and Wang (2016), there are two types of mobile phone data: call detail record (CDR) data and sightings data. These two data types differ in temporal resolution, spatial resolution, and user interactions. Sightings data has higher temporal and spatial resolutions but is not based on user interactions as the case for CDR data

History

A handheld mobile radio telephone service was envisioned in the early stages of radio engineering. In 1917, Finnish inventor Eric Tigerstedt filed a patent for a "pocket-size folding telephone with a very thin carbon microphone". Early predecessors of cellular phones included analog radio communications from ships and trains. The race to create truly portable telephone devices began after World War II, with developments taking place in many countries. The advances in mobile telephony have been traced in successive "generations", starting with the early zeroth-generation (0G) services, such as Bell System's Mobile Telephone Service and its successor, the Improved Mobile Telephone Service. These 0G systems were not cellular, supported few simultaneous calls, and were very expensive. The first handheld cellular mobile phone was demonstrated by John F. Mitchell^[11][12] and Martin Cooper of Motorola in 1973, using a handset weighing 2 kilograms (4.4 lb). The first commercial automated cellular network (1G) analog was launched in Japan by Nippon Telegraph and Telephone in 1979. This was followed in 1981 by the simultaneous launch of the Nordic Mobile Telephone (NMT) system in Denmark, Finland, Norway, and Sweden.^[13] Several other countries then followed in the early to mid-1980s. These first-generation (1G) systems could support far more simultaneous calls but still used analog cellular technology. In 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone.

In 1991, the second-generation (2G) digital cellular technology was launched in Finland by Radiolinja on the GSM standard. This sparked competition in the sector as the new operators challenged the incumbent 1G network operators. The GSM standard is a European initiative expressed at the CEPT ("Conférence Européenne des Postes et Telecommunications", European Postal and Telecommunications conference). The Franco-German R&D cooperation demonstrated the technical feasibility, and in 1987 a Memorandum of Understanding was signed between 13 European countries who agreed to launch a commercial service by 1991. The first version of the GSM (=2G) standard had 6,000 pages. The IEEE and RSE awarded to Thomas Haug and Philippe Dupuis the 2018 James Clerk Maxwell medal for their contributions to the first digital mobile telephone standard.^[14] In 2018, the GSM was used by over 5 billion people in over 220 countries. The GSM (2G) has evolved into 3G, 4G and 5G. The standardisation body for GSM started at the CEPT Working Group GSM (Group Special Mobile) in 1982 under the umbrella of CEPT. In 1988, ETSI was established and all CEPT standardization activities were transferred to ETSI. Working Group GSM became Technical Committee GSM. In 1991, it became Technical Committee SMG (Special Mobile Group) when ETSI tasked the committee with UMTS (3G).

خلاصه تحقیق

Mobile Phone is often also called “cellular phone”. It is a device mainly used for a voice call. Presently technological advancements have made our life easy. Today, with the help of a mobile phone we can easily talk or video chat with anyone across the globe by just moving our fingers. Today mobile phones are available in various shapes and sizes, having different technical specifications and are used for a number of purposes

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