Mobile phones2

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Price: Yuan330
Add Time: 2018-06-02 17:21:15
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generation of mobile phones (3G), mainly in European GSM and American CDMA. They are digital, besides voice communication, it can also send and receive SMS, wireless application protocols, and so on. GSM is most popular in mainland China and Taiwan, and CDMA phones are also popular. The industry is moving towards the fourth generation of mobile phones (4G). In addition to the typical telephone function, the phone keyboard includes PDA, game machine, MP3, camera, photography, recording, GPS, Internet and so on. It has the trend of developing the PDA with the function of the mobile phone. The mouthpiece, ear bearing, and the corresponding microphone and receiver are mounted on a single handle. Formerly known as mobile phones, mobile phones, mobile phones, fax, is portable, mobile phone terminal [13] can be moved in a larger range.

According to the analysis, although the basic protection function of the mobile phone safety products is complete, there is still a shortage in the prevention of harassment, privacy protection and data protection. There is still a big market space in the future. QQ handset housekeeper, security housekeeper, netqin and other security manufacturers have declared to enter the field of cloud security in succession, and will be moved in 2013. The key year for mobile cloud security to accelerate landing is that all major security vendors will continue to increase investment in mobile cloud security solutions.

The first generation mobile phone (1G) refers to the analog mobile phone, which is the cell phone that appeared in Hongkong, the United States, and other films and television works in 80s and 90s twentieth Century. The first cell phone developed was Dr. Cooper from the United States. Because of the limit of battery capacity at the time and the constraints of analog modulation technology, such as large antenna and integrated circuit, this kind of mobile phone can only be mobile and can not be portable. Many people call this kind of mobile phone "brick" or "black diamond".

The mobile phone has a variety of formats, such as NMT, AMPS, TACS, but basically the use of frequency division multiplexing can only carry out voice communication, the effect is unstable, and the security is insufficient, the wireless bandwidth utilization is inadequate. This kind of mobile phone is similar to a simple radio duplex radio. The call is locked at a certain frequency, so the use of FM radio can intercept calls. [14]

The second generation of mobile phones (2G) are also the most common mobile phones. Usually these phones use GSM or CDMA's very mature standards, which have stable call quality and suitable standby time. In order to meet the needs of data communication in the second generation, some intermediate standards are also supported on mobile phones, such as GPRS for MMS services and WAP services for Internet services, as well as a variety of Java programs.

Some mobile phone manufacturers call some of their phones 2.5G phones, which feature the GPRS function [15].

Some mobile phone manufacturers also call some of their phones 2.75G phones, which feature a faster GPRS function than [3] EDGE [9].


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