English
wireless mobile communication WirelessMobileCommunication
development background
broadband wireless mobile communication industry has become a field of the world's most talked about development of the communication industry one. Future broadband wireless mobile communication technology evolution, intelligent terminal and business applications will bring a broad market space, it is an important driving force for the development of the global communications industry. National major projects have clear requirements: the master mobile communications core technology and independent intellectual property rights as to enhance the industry's core competitiveness of my country's communications breakthrough. And develop broadband wireless mobile communications industry will be important.
Status
Today, mobile communications and the flow of the sales staff, delivery vehicles, geologists and other people to keep in touch. Mobile computer users to use wireless communications and a corporate network, and exchange e-mail, file transfer, receive personal news or other information addressed to their mobile computer or personal digital assistant (PDA) is. The PDA can be AppleNewton, EO and GenenralMagic equipment. With the development of science and technology, the transmission rate will be higher and higher, and the price will be lower and lower. Mobile users will spend a lot of time to query corporate databases or participate in online meetings and talks by connecting to the wireless network.
direction of development
operating system vendors have begun to consider mobile users' questions, they created a number of new features, such as tracking the location of mobile users, and maintain from one session to another environment session. For example, when a user moves from one location to another location, he or she disconnects; before reconnecting the system to a remote fixed location, the operating system can automatically restore the connection and restore the system environment on a desktop session. If a user is accessing a database, then when he or she is making connections you can find on the results of a database query. PDA used with most operating systems and applications different interfaces. However, with the growth of mobile computer users, vendors are working to integrate these systems.
Overview
mobile computing naturally implicated phone telecom telecommunications company or other service providers. The user must be concerned about access levels (range and signal penetration), the data transfer rate, before the delivery of storage capacity, these capabilities ensure that users return to work within the scope of the investigation may take their messages. Using previously described mobile communication system in which the data transfer rate is very low, about from 8Kbps to 19.2Kbps. Demand error checking will severely reduce the transmission rate.
The wireless device may be unidirectional, or may be bidirectional. Comprising a one-way communication only receives signals BP. Using two-way communication device and a cellular packet radio transmission. SkyTel provides three levels of service: Transfer phone number, voice - mail message reminders, or e-mail message alerts. EMBARC compete with SkyTel, which provides messaging capability has 30,000 characters, and SkyTel but only 240 characters. EMBARC further provides for simultaneous transmission, for example, the user may modify information in different remote systems.
bidirectional communication system includes a packet radio network and a cellular system, as follows:
Packet-RadioCommunication packet radio communication
The first transmission packet radio communication decomposed into many small source and destination addresses contained, and a digital packet error detection information. These packets are linked to a satellite on, and then broadcast. Receiving apparatus receives only addressed to its digital packet. Since this is a two-way transmission, so you want to use error checking and error correction technology.
CellularDigitalPacketCommunication cellular digital packet communication
is a method of providing cellular communications between users and their families, office or mobile two-way communication network computing device. These devices have the e-mail processing capability, and can transfer files and other information. Since these devices are, in essence, it is bi-directional, and thus require troubleshooting and support error correction technology. See, "Cellular Digital Packet Data."
BobMetcalfe on Infoworld (8-16-93) was presented with the mobile computing manufacturers have the opposite view. He pointed out that the trend is just a temporary wireless communication, and said: "We have been growing electromagnetic signal contamination universe, never never have enough MHz frequency required information will be broadcast in all directions and only one user to receive it, this is a huge waste of energy. "