Edit this section of the application of cell phone gravity sensing technology The use of piezoelectric effect to achieve, in simple terms is is to measure the internal piece of weight (weight and piezoelectric chip made into one) gravity orthogonal to the two directions of the magnitude of the component force to determine the horizontal direction. Introduction to Hard Disk Gravity Sensing Technology The gravity sensing device consists of three parts: the sensor, the processor and the controller. The inductor is responsible for detecting the state of the memory and calculating the gravity acceleration value of the memory; the processor judges whether the acceleration value is out of the safe range; and the controller is responsible for controlling the head to be locked or released out of the safe parking area. Once the sensor detects and the processor determines that the current gravitational acceleration exceeds the safe value, the controller hardware controls the magnetic head to stop reading and writing and quickly return it to its position, locking it in the proprietary head parking area. This series of actions will be completed within 200 milliseconds. The product resumes operation only after the sensing device detects that the acceleration value has returned to the normal value range.
Gravity sensing in mobile storage: Scientific experiments have proved that the general memory in the non-electrified, shock resistance of 1000G, and after the power work, shock resistance is less than 200G, a very slight bump may cause the disk bad channel. Therefore, only by effectively ensuring the safety of the product in working condition can we ultimately ensure the safety of the data contained therein.
Gravity sensing technology", using the principle of gravitational acceleration, once the accident is detected, the head can be withdrawn to the safe parking area in the instant of the fall, which can enhance the safety performance of the mobile memory by more than 500%, and reach or even exceed the level of anti-vibration in the state of non-electricity, which fundamentally ensures the anti-vibration performance of the mobile memory under the working condition, and thus guarantees the safety of data information in any state.
Apple developed the first gravity-sensing model Other applications Gravity-sensing technology has also been used in other areas. For example, smart electric cars, game consoles, computers, and so on
Editorial Principle The realization of the direction sensor is based on the iPhone's built-in accelerometer, which is a three-axis accelerometer divided into the X-axis, the Y-axis, and the Z-axis. These three axes form a three-dimensional space that is large enough to detect your movements on the iPhone. In practice, the angle formed by these three axes (or any two axes) is usually used to calculate the angle at which the iPhone is tilted, and thus the value of gravitational acceleration.
By sensing the total amount of inertial force in a given direction, the accelerometer can measure both acceleration and gravity. iPhone's three-axis accelerometer means that it is able to detect motion or gravitational pull in three dimensions. As a result, the accelerometer can indicate not only how the phone is being held (or the auto-rotate feature), but also whether the phone is facing up or down if it's on a table.
The accelerometer measures the gravitational pull (g), so when the accelerometer returns a value of 1.0, it indicates that 1g is sensed in a particular direction.If the iPhone is held stationary without any movement, the force exerted on it by the Earth's gravity is approximately 1g.If the iPhone is held vertically in the longitudinal direction, the iPhone detects and reports the force exerted on its y-axis as approximately 1g. If iPhone is held at an angle, the force of 1g is distributed across different axes, depending on how iPhone is held. When holding the iPhone at a 45 degree angle, the 1g of force is evenly distributed across both axes.
In normal use, the accelerometer does not detect values much greater than 1g in either axis. If the accelerometer detects a value much greater than 1g, then it can be determined that it is a sudden movement. If the iPhone is shaken, then the accelerometer will detect a large force in one or more axes, and if it is thrown or dropped, then the accelerometer will detect a small force in one or more axes.
wi-fi definition
Wireless router
Wi-Fi was originally an acronym for wireless fidelity, the full English name for Wi-Fi is wireless fidelity, pronounced waifai (pinyin pronunciation, all with one sound), English phonetic symbol /?wa?fa?/, wireless [English] [?wa?l? s] fidelity [Eng] [fi?deliti].
In the context of wireless local area networks (WLANs) is the term "wireless compatibility authentication", which is essentially a commercial authentication, but also a wireless networking technology, which used to connect computers to the Internet through wires, but now connects them to the Internet through radio waves, which is commonly used for a wireless router, and then in the radio wave coverage effective range of the router can be used for WiFi, which can be used to connect computers to the Internet. The effective range of coverage of the wireless router can be used WIFI connection for networking, if the wireless router is connected to an ADSL line or other Internet lines, it is also known as "hotspot".
Introduction Wi-Fi is commonly known as wireless broadband (China Telecom calls CDMA 1X/3G wireless broadband). The difference between Wi-Fi and Wlan is that WLan is a wireless local area network (WLAN), and Wi-Fi is a technology, and Wlan is a type of Wi-Fi.
Phones with Wi-Fi support
The term Wi-Fi was developed by a group called "Wireless Ethernet". The so-called Wi-Fi is an industry term issued by an organization called Wireless Ethernet Compatibility Alliance (WECA), which translates to "Wireless Compatibility Authentication" in Chinese. It is an industry term issued by the organization "Wireless Ethernet Compatibility Alliance" (WECA). It is a short-range wireless transmission technology that can support radio signals for Internet access within a range of several hundred feet. With the development of the technology, and the emergence of standards such as IEEE 802.11a and IEEE 802.11g, the IEEE 802.11 standard is now collectively referred to as Wi-Fi. From an application level, in order to utilize Wi-Fi, the user first needs to have a Wi-Fi-compatible client device.
Wi-Fi is an Internet technology that helps users access e-mail, the Web, and streaming media by providing wireless broadband Internet access. It is also a fast and convenient way to access the Internet at home, in the office or on the go. Places where Wi-Fi networks can be accessed are called hotspots. Wi-Fi or 802.11G operates in the 2.4Ghz band and supports speeds of up to 54Mbps (802.11N operates at 2.4Ghz or 5.0Ghz, with a maximum speed of 600Mbps). There are two other protocols in the 802.11 space, including (a) and (b). They are also in public use, but 802.11G/N is most commonly used in the world.
Bluetooth + wifi wireless devices
Wi-Fi hotspots are created by installing an access point on an Internet connection. This access point transmits the wireless signal over a short range, typically covering 300 feet. When a Wi-Fi-enabled device, such as a Pocket PC, encounters a hotspot, that device can wirelessly connect to that network. Most networks are located in places that are accessible to the general public, such as airports, coffee shops, hotels, bookstores, and campuses. Many homes and offices also have Wi-Fi networks. While some hotspots are free, most stable public **** Wi-Fi networks are provided by private Internet Service Providers (ISPs) and therefore charge users a fee when they connect to the Internet.
The full name is Wireless Fidelity. 802.11b is sometimes incorrectly labeled Wi-Fi, which is actually a trademark of the Wireless LAN Alliance (WLANA), which only guarantees that goods using the trademark will work with each other, and has virtually nothing to do with the standard itself. However, people have since grown accustomed to using WIFI to refer to the 802.11b protocol. Its biggest advantage is its high transmission speed, which can reach 11Mbps, and its long effective distance, as well as its compatibility with various existing 802.11 DSSS devices. The laptop technology, Centrino, is based on this standard.
The IEEE ([American] Institute of Electronics and Electrical Engineers) 802.11b wireless network specification is an extension of the IEEE 802.11 network specification, with a maximum bandwidth of 11 Mbps, and in the case of weak signals or interference, the bandwidth can be adjusted to 5.5 Mbps, 2 Mbps, and 1 Mbps, with automatic bandwidth adjustments, effectively guaranteeing network stability and reliability. Its main features are: fast speed, high reliability, communication distance up to 305 meters in open areas and 76 meters to 122 meters in closed areas, easy to integrate with existing wired Ethernet networks
Wi-Fi enabled laptops
, and lower cost of networking.
Wi-Fi (WirelessFidelity), formally known as "IEEE802.11b," is a short-range wireless technology used in offices and homes, like Bluetooth. While this technology is less secure than Bluetooth in terms of data security, it is slightly better in terms of airwave coverage, and Wi-Fi has a range of up to about 300 feet (90 meters), which can be used in offices and even smaller buildings.
USB wireless card
WiFi kiosk
Edit this section of the formation
Wireless network setup
General setup of a wireless network is equipped with a wireless card and an AP, which can be used in a wireless mode with the existing wired structure to share network resources, the cost and complexity of the setup is far less than that of a traditional wired network. The cost and complexity of setup is much lower than traditional wired network. If it is just a peer-to-peer network of a few computers, you can also do not need an AP, but only need to equip each computer with a wireless network card, AP is short for AccessPoint, which is generally translated as "wireless access point", or "bridge". It mainly plays a role in the media access control layer MAC wireless workstations and wired local area network bridge. With an AP, like a hub in a wired network, wireless workstations can quickly and easily connect to the network. Especially for the use of broadband, WiFi is more advantageous, wired broadband network (ADSL, cell LAN, etc.) to the home, connected to an AP, and then install a wireless network card in the computer can be. Ordinary families have an AP is enough, and even the user's neighborhood is authorized, then there is no need to add ports, but also to *** enjoy the way to the Internet.
Editorial Applications Because WiFi's frequency bands do not require any telecom licenses in the world, WLAN wireless devices provide a wireless air interface that can be used worldwide at extremely low cost and with very high data bandwidth. Users can quickly browse the web and make and receive phone calls anywhere in the WiFi coverage area. Other WLAN-based broadband data applications, such as streaming media, online games, and more
Desktop Wi-Fi
are even more desirable. With WiFi, we can make long-distance calls (including international calls), browse the web, send and receive e-mail, download music, and deliver digital photos without worrying about slow speeds and high costs.
WiFi is becoming more and more widely used in handheld devices, and smartphones are one of them. Unlike Bluetooth technology, which was earlier used in cell phones, WiFi has a larger coverage area and higher transmission rates, making WiFi phones the current trend in the mobile communications industry.
Now the coverage of WiFi is getting wider and wider in China, and there are WiFi interfaces in high-class hotels, luxury residential areas, airports, and coffee shops. When we go to travel and work, we can use our handheld devices to surf the Internet to our heart's content in these places.
Editing the Market The commercialization of Wi-Fi on a large scale has seen few successful precedents in the world. The problem is centered on two aspects: first, the large operators do not recognize this model; second, the lack of an effective business model itself. However, wireless LAN based on Wi-Fi technology has become increasingly popular, which will mean that it can be applied very easily in the future. Once the existence of Wi-Fi networks in public places, to solve the problem of interconnection, high charges, roaming operators, Wi-Fi will be transformed from a successful technology into a successful business.
Edit this paragraph WAPI and WIFI WIFI unblocking issue again attracted attention
WIFI (WirelessFidelity) and Bluetooth technology, the same belongs to the short-range wireless technology, is a network transmission standard. In daily life, it has long been widely used and brings great convenience to people: white-collar workers browse the web in Starbucks, journalists send back articles at the conference site, and ordinary people choose to use cell phones or multiple laptops to access the Internet wirelessly in their own homes at their own whims, all of which are inseparable from WIFI.
But it has always been prohibited by the Ministry of Industry and Information Technology (MIIT) to allow cell phones supporting WIFI to obtain network access licenses in China. In the country to obtain access to the network license, foreign brands of cell phones to enter the Chinese mainland market must be removed from the WIFI module or shielding the function, to become a lot of people jokingly referred to as the "castrated" version of the phone.
"If the Chinese market is the 'castrated version' of the iphone, then the day of release is when I go to buy the water goods." Many iphone fans who have been dissatisfied with the banning of the WIFI function have coincidentally expressed similar views.
To understand the important reason why WIFI is banned in China, we have to mention the existence of another standard --- WAPI. 2003 introduced the WAPI standard (the full name of the wireless local area network (WLAN) identification and confidentiality infrastructure), as China's own research and development, with independent intellectual property rights, the wireless LAN security technology standard. The WAPI standard (full name of WLAN identification and confidentiality infrastructure) introduced in 2003, as a wireless LAN security technology standard independently developed by China with independent intellectual property rights, is two different protocols with WIFI, and the biggest difference is that the security encryption technology is different. For the consideration of Internet security, China has been strongly recommending WAPI as an independent international standard. The reason why the WIFI function of domestic cell phones has been canceled is precisely because the WIFI protocol is not officially recognized by mainland China.
Is WAPI a victory or WIFI lifting the ban in disguise
China intended to make the WAPI standard mandatory from June 1, 2004, but it was resisted by U.S. companies, such as Intel, and even the U.S. government until June 2009, when WAPI was first unanimously agreed upon by the U.S., the U.K., France and other members of more than 10 countries and was to be advanced in the form of a standalone text as an international standard.
Many industry insiders still remember the WAPI and WIFI dispute from five years ago.
At the end of 2003, the AQSIQ and the Standardization Administration of China (SAC) issued a notice saying that from June 1, 2004, they would begin to enforce the WAPI standard. The move was met with resistance from U.S. companies such as Intel and even the U.S. government, which threatened to stop wireless operations in China, claiming that Western companies preferred their own standards to the WAPI standard.
After negotiations between the U.S. and China on April 22, 2004, then Vice Premier Wu Yi said China agreed to the U.S. request not to make the WAPI standard mandatory. In July, China formally submitted a WAPI proposal to the International Standards Organization, but then China's WAPI standard encountered unprecedented obstruction, and the WAPI standard was forced to become an international standard on hold.
Who would have thought that this wait is 5 years, until June 2009, things have a major turnaround. China WAPI Industry Alliance publicly confirmed that in the recent International Standards Organization ISO/IECJTC1/SC6 meeting, WAPI for the first time by the U.S., Britain, France and other more than 10 countries members of the unanimous consent of the form of an independent text will be advanced to international standards. Some experts regarded this event as "the first time the U.S. side began to fulfill the 'promote WAPI as an international standard' commitment to the landmark event."
According to the latest policy of the Ministry of Industry and Information Technology (MIIT) at present, any cell phone with WAPI function can enter the network to detect and obtain the network license, the principle is that such cell phones can use WAPI access when there is a WAPI network, and when the search can not be made for WAPI, the wireless network can be accessed through WIFI, but pure WIFI cell phones still can not be listed.
Editorial Features A Wi-Fi connection point network member and structure station (Station) , the most basic component of the network.
Cell phones with wifi capabilities (3 photos)
Basic Service Set (BSS) is the most basic service unit of the network. The simplest service unit can consist of only two sites. Sites can be dynamically associated (associate) to the basic service unit.
Distribution System (DS). The distribution system is used to connect the different basic service units. The medium used by the Distribution System is logically distinct from the medium used by the Basic Service Units, although they may be physically the same medium, e.g., the same radio frequency band.
Access Point (AP). An access point has both the identity of a regular station and access to the distribution system.
Extended Service Set (ESS). A combination of a distribution system and a basic service unit. This combination is logical, not physical - different basic service units may be geographically distant from each other. Distribution systems can also use a wide variety of technologies.
The gateway (Portal), is also a logical component. Used to link wireless LANs to wired LANs or other networks.
There are three types of media, the wireless media used by the site, the media used by the distribution system, and the media used by other LANs integrated with the wireless LAN. Physically they may overlap each other.
IEEE802.11 is only responsible for addressing the wireless media used at the site. Addressing of distribution systems and other LANs is outside the scope of wireless LANs.
IEEE802.11 does not specifically define a distribution system, but only the services that a distribution system should provide. The whole wireless LAN defines 9 kinds of services,
5 kinds of services belong to the task of the distribution system, respectively, association (Association), end of association (Diassociation), distribution (Distribution), integration (Integration), and re-association (Reassociation).
The four services belonging to the site's tasks are, Authentication, Deauthentication, Privacy, and MSDU delivery.
Editorial Features Unlimited popularity, Wi-Fi has also become a "superstar". Wi-Fi can be said to be a "Golden Pavilion", from eight aspects of the comprehensive packaging themselves. The following are from the bandwidth, signal, power consumption, security, network integration, personal services, mobile features, client analysis of Wi-Fi's unique features. [1] Wider bandwidth Although the IEEE has initiated two projects intended to increase the data rate of the 802.11 standard to a gigabyte or several gigabytes, there is still no first draft.
More practically, the 802.11n standard raises the data rate by one level, which can be adapted to different functions and devices. Currently, all 11n wireless transceivers support two spatial data streams, and two or three antenna combinations can be used for sending and receiving data. Apple's latest Wi-Fi iPod Touch contains a Broadcom s wireless chip that supports the 11n standard.
Soon there will be chips that support three or four streams, with data rates of 450Mbps and 600Mbps, respectively, and in early 2009, Quantenna Communications said it had developed a 4x4 chip that could carry high-definition digital TV signal streams.
Wi-Fi equipment provider Ruckus Wireless *** with the founder and CTO William Kish said: "Although there will not be a lot of client devices to support four spatial streams, as long as the correct design of the access point, will be able to take advantage of the 600Mbps physical layer data rate, to achieve high-speed wireless backbone network. "
You can connect these high-end nodes via the 802.11s standard to form an Internet-like Wi-Fi network with redundancy capabilities. Stronger RF signals More optional performance features in 11n will be available in wireless chips, which wireless clients and wireless access points utilize to make radio frequency (RF) signals more resilient, stable, and reliable, in other words more like a wire.
"The new 11n physical layer technology will make Wi-Fi more powerful, with higher data rates and longer distances within a given range," said William McFarland, CTO of wireless chip maker Atheros.
These performance features include: low-density parity-check codes, which improve error-correction capabilities; transmit beamforming, which uses feedback from Wi-Fi clients to allow a single access point to centralize the client's RF signals; and spatial temporal packet coding (STBC), which uses multiple antennas to improve signal reliability.
McFarland said, "Today you take a Wi-Fi-enabled laptop and spare the building for a week, and you'll see the data rate drop or go away, but with STBC, the connection will continue to work."
Wi-Fi consumes less power 802.11n makes significant innovations in power consumption and management. Significant innovations that not only extend the battery life of Wi-Fi smartphones, but can also be embedded in other devices such as medical monitoring devices, building control systems, real-time location tracking tags and consumer electronics. Data can be constantly monitored and collected and can be personalized based on a user's identity and location.
What other modern RF technologies can't do, Wi-Fi can now do," writes Network World blogger Craig Mathias.
Atheros's McFarland says, "With enterprise wireless LANs, the infrastructure is in place, and now it's just a matter of adding low-power sensors.
Embedded Wi-Fi wireless datacom vendors Summit recently announced 802.11a wireless communications in the form of a variety of plug-ins to allow devices to use the uncongested 5GHz band, Gainspan offers 11b/g wireless devices with an IP software stack that consumes so little power that a standard battery can run for years,Redpine. Signals provides a single stream embedded into 11n wireless communications. Improved Security The most devastating impact of the Internet is the harm done to users through identity theft, denial-of-service attacks, privacy violations, spying, and the lack of appropriate means of trust, and mobile networks have made this worse by potentially exposing users to devastating risks if they trust the Wi-Fi connection they are currently open to.
The IEEE recently ratified the 802.11w standard, which protects wireless management frames and makes wireless links work better, said Matthew Gast, principal analyst at Networks, adding, "Wi-Fi clients can now receive and adopt 'landed network Previously this information could be spoofed using MAC addresses by hackers breaching the access point, and the 11w standard cuts off such attacks."
Michael Tennefoss, director of strategic marketing at Aruba Networks, said, "Wi-Fi will use identity-based security, where the security policy is associated with the user in the Wi-Fi network, not with the port, which has the benefit of allowing users to move around their homes, offices, hotels, branches, and public ****places. and public ****places on the move and security is not compromised." Collaboration with non-Wi-Fi networks If you're a T-Mobile Wi-Fi subscriber, but you're currently in range of a hotspot provided by another carrier, you can't use Wi-Fi. In the future, your Wi-Fi device will be able to look up "extranet (other carrier's wireless network)" services and securely access them, and your user ID will roam with you, enabling you to use a variety of different Wi-Fi services.
With the 802.11u standard in place, users will have more flexibility to use wireless networks, and the future of Wi-Fi in order to advertise their services to the public, as long as you obey its terms you can link to them, depending on your identity, you can access a subset of all or some of the services available on other networks, and in case of an emergency you can get the bare minimum of connectivity and functionality,802.11u The standard is scheduled for final approval in June 2010. Self-managing clients Wi-Fi device manufacturers have come up with a number of ways to make their devices work smarter with wireless access points, and while the management of the wireless access points themselves is now fairly sophisticated, there's still a gap in the management of wireless clients.
If you adopt new Wi-Fi management protocols at both the access point and the client, collaboration between them can be even more interesting.
Imagine your netbook Wi-Fi adapter, or a Wi-Fi VoIP phone saving power when it's not transmitting and receiving a wireless signal, or only ****enjoying location data, and the access point can redirect a Wi-Fi voice conference to a more desirable neighboring access point, or to a less loaded access point.The Wi-Fi network can localize the a client's location, for example, outside a building, or on a street, and can grant the client connection operation based on this data.
The 802.11v standard, which could be finalized by the end of July 2010, will have a number of enhancements in terms of Wi-Fi management, which will add an array of counters for statistic collection, increase power management, improve battery life, and improve location data support.
Client coordination is also being addressed in the Wi-Fi Alliance's Wi-Fi Multimedia Admission Control specification, which is currently under development, and which allows wireless networks to negotiate and manage streaming sessions so that high-definition video doesn't cut off voice over Wi-Fi sessions at the same access points, and the Wi-Fi Alliance is considering specific Wi-Fi in order to manage the specification, notably Borrowing from several related IEEE standards and then adding additional wireless management features. Improved Mobility RF management was lacking in previous standards because access points and clients were often unaware of each other, and of neighboring wireless devices, which were only aware of their own radio wave frequencies, a limitation that made it difficult to manage RF.
For example, when a Wi-Fi phone enters the range of an access point, it triggers a blind search process, and if the client could ask its access point, "Who are your neighbors, and which is the best access point to connect to?"
The IEEE 802.11k wireless resource management standard, released last year, addresses this issue by improving mobility through intelligent RF management, but Wi-Fi device manufacturers have implemented a range of proprietary features to address this challenge, as exemplified by version 2.0 of Aruba's Adaptive Wireless Management technology.
Meanwhile, the Wi-Fi Alliance is using some of the features of 11k to conceptualize its voice enterprise certification, with the goal of optimizing call quality for large-scale, enterprise-grade voice-over-Wi-Fi environments.Wi-Fi personal zones Current Wi-Fi is an end-to-end connection; the Wi-Fi network of the future, where your device connects directly to other client devices no matter where they are, for example Ozmo devices with low-power chips allow peripherals to connect directly to your laptop via Wi-Fi.
The Wi-Fi Direct (WFD) program, recently announced by the Wi-Fi Alliance, will let the Wi-Fi card on your laptop bypass access points and connect directly to a wireless printer, digital camera, projector, sensor, or plasma screen. An industry specification, WFD will introduce new protocol implementations in firmware so that no hardware changes are required.
Meanwhile, Wi-Fi access points can also be turned into point-to-point connection engines through the 802.11z standard (slated for completion in July 2010), which will provide extensions for direct-connect configurations, where a client device requests permission from one access point to connect directly to another nearby client device, but the data doesn't pass through the access point, and the client remains connected to the access point with the access point providing the full set of security and management services.
Editorial Certification The types of certifications currently published by the Wi-Fi Alliance are:
*WPA/WPA2: WPA/WPA2 is a test program established for single-mode, dual-mode, or dual-band products based on the IEEE 802.11a, 802.11b, and 802.11g. It includes verification of communication protocols, verification of wireless network security mechanisms, and network transmission performance and compatibility testing.
* WMM (Wi-Fi MultiMedia): WMM testing is designed to verify that bandwidth-guaranteed mechanisms are functioning properly across different wireless network devices and different security settings when delivering video and multimedia over a wireless network.
* WMM Power Save: When delivering multimedia over Wi-Fi, how to manage the standby time of the Wi-Fi device to extend the battery life without affecting its functionality can be verified through the WMM Power Save test.
*WPS (Wi-Fi Protected Setup): This is a certification released in early 2007 to allow consumers to set up their Wi-Fi devices in a simpler and more secure manner. Currently, WPS allows the setting of wireless network devices through Pin Input Config (PIN), Push Button Config (PBC), USB Flash Drive Config (UFD) and Near Field Communication, Contactless Token Config (NFC).
* ASD (Application Specific Device): This is for wireless network devices with special applications other than wireless network access points and stations, such as DVD players, projectors, printers, and so on.
* CWG (Converged Wireless Group): A test program that measures the RF portion of Wi-Fi mobile converged devices.
* CWG (Converged Wireless Group).