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Assisted GNSS
Assisted GNSS (A-GNSS) is a GNSS augmentation system that often significantly improves the startup performance—i.e., time-to-first-fix (TTFF)—of a global navigation satellite system (GNSS). A-GNSS works by providing the necessary data to the device via a radio network instead of the slow satellite link, essentially "warming up" the receiver for a fix. When applied to GPS, it is known as assisted GPS or augmented GPS (abbreviated generally as A-GPS and less commonly as aGPS). Other local names include A-GANSS for Galileo and A-Beidou for BeiDou. A-GPS is extensively used with GPS-capable cellular phones, as its development was accelerated by the U.S. FCC's 911 requirement to make cell phone location data available to emergency call dispatchers. Background Every GPS device requires orbital data about the satellites to calculate its position. The data rate of the satellite signal is only 50 bit/s, so downloading orbital information like ephemerides and the almanac directly fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WCDMA
The Universal Mobile Telecommunications System (UMTS) is a 3G mobile cellular system for networks based on the GSM standard. UMTS uses wideband code-division multiple access (W- CDMA) radio access technology to offer greater spectral efficiency and bandwidth to mobile network operators compared to previous 2G systems like GPRS and CSD. UMTS on its provides a peak theoretical data rate of 2 Mbit/s. Developed and maintained by the 3GPP (3rd Generation Partnership Project), UMTS is a component of the International Telecommunication Union IMT-2000 standard set and compares with the CDMA2000 standard set for networks based on the competing cdmaOne technology. The technology described in UMTS is sometimes also referred to as Freedom of Mobile Multimedia Access (FOMA) or 3GSM. UMTS specifies a complete network system, which includes the radio access network ( UMTS Terrestrial Radio Access Network, or UTRAN), the core network ( Mobile Application Part, or MAP) and the authenti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mobile Phone Tracking
Mobile phone tracking is a process for identifying the location of a mobile phone, whether stationary or moving. Localization may be affected by a number of technologies, such as the multilateration of radio signals between (several) cell towers of the network and the phone or by simply using GNSS. To locate a mobile phone using multilateration of mobile radio signals, the phone must emit at least the idle signal to contact nearby antenna towers and does not require an active call. The Global System for Mobile Communications (GSM) is based on the phone's signal strength to nearby antenna masts. Mobile positioning may be used for location-based services that disclose the actual coordinates of a mobile phone. Telecommunication companies use this to approximate the location of a mobile phone, and thereby also its user. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wi-Fi Positioning System
Wi-Fi positioning system (WPS, WiPS or WFPS) is a geolocation system that uses the characteristics of nearby Wi‑Fi access points to discover where a device is located. It is used where satellite navigation such as GPS is inadequate due to various causes including multipath and signal blockage indoors, or where acquiring a satellite fix would take too long. Such systems include assisted GPS, urban positioning services through hotspot databases, and indoor positioning systems. Wi-Fi positioning takes advantage of the rapid growth in the early 21st century of wireless access points in urban areas. The most common technique for positioning using wireless access points is based on a rough proxy for the strength of the received signal ('' received signal strength indicator'', or ''RSSI'') and the method of "fingerprinting".P. Bahl and V. N. Padmanabhan, “RADAR: an in-building RF-based user location and tracking system,” in Proceedings of 19th Annual Joint Conference of the IEEE ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ionospheric
The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on Earth. Travel through this layer also impacts GPS signals, resulting in effects such as deflection in their path and delay in the arrival of the signal. History of discovery As early as 1839, the German mathematician and physicist Carl Friedrich Gauss postulated that an electrically conducting region of the atmosphere could account for observed variations of Earth's magnetic field. Sixty years later, Guglielmo Marconi received the first trans-Atlantic radio signal on December 12, 1901, in St. John's, Newfoundland (now in Canada) using ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Site
A cell site, cell phone tower, cell base tower, or cellular base station is a cellular frequencies, cellular-enabled mobile device site where antenna (electronics), antennas and electronic communications equipment are placed (typically on a Radio masts and towers, radio mast, tower, or other raised structure) to create a cell, or adjacent cells, in a cellular network. The raised structure typically supports antenna and one or more sets of transmitter/receivers transceivers, digital signal processors, control electronics, a GPS receiver for timing (for CDMA2000/IS-95 or GSM systems), primary and backup electrical power sources, and sheltering. Multiple cellular providers often save money by mounting their antennas on a common shared mast; since separate systems use different frequencies, antennas can be located close together without interfering with each other. Some provider companies operate multiple cellular networks and similarly use colocated base stations for two or more ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ephemeris
In astronomy and celestial navigation, an ephemeris (; ; , ) is a book with tables that gives the trajectory of naturally occurring astronomical objects and artificial satellites in the sky, i.e., the position (and possibly velocity) over time. Historically, positions were given as printed tables of values, given at regular intervals of date and time. The calculation of these tables was one of the first applications of mechanical computers. Modern ephemerides are often provided in electronic form. However, printed ephemerides are still produced, as they are useful when computational devices are not available. The astronomical position calculated from an ephemeris is often given in the spherical polar coordinate system of right ascension and declination, together with the distance from the origin if applicable. Some of the astronomical phenomena of interest to astronomers are eclipses, apparent retrograde motion/planetary stations, planetary es, sidereal time, positions for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base Transceiver Station
A base transceiver station (BTS) or a baseband unit (BBU) is a piece of equipment that facilitates wireless communication between user equipment (UE) and a network. UEs are devices like mobile phone A mobile phone or cell phone is a portable telephone that allows users to make and receive calls over a radio frequency link while moving within a designated telephone service area, unlike fixed-location phones ( landline phones). This rad ...s (handsets), WLL phones, computers with wireless Internet connectivity, or antennas mounted on buildings or telecommunication towers. The network can be that of any of the wireless communication technologies like GSM, CDMA, wireless local loop, Wi-Fi, WiMAX or other wide area network (WAN) technology. BTS is a part of a '' base station'' (BS). Though the term BTS can be applicable to any of the wireless communication standards, it is generally associated with mobile communication technologies like GSM and CDMA. In this rega ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Global Positioning System
The Global Positioning System (GPS) is a satellite-based hyperbolic navigation system owned by the United States Space Force and operated by Mission Delta 31. It is one of the global navigation satellite systems (GNSS) that provide geolocation and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. It does not require the user to transmit any data, and operates independently of any telephone or Internet reception, though these technologies can enhance the usefulness of the GPS positioning information. It provides critical positioning capabilities to military, civil, and commercial users around the world. Although the United States government created, controls, and maintains the GPS system, it is freely accessible to anyone with a GPS receiver. Overview The GPS project was started by the U.S. Department of Defense in 1973. The first prototype spacecraft was launched in 1978 an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internet Service Provider
An Internet service provider (ISP) is an organization that provides a myriad of services related to accessing, using, managing, or participating in the Internet. ISPs can be organized in various forms, such as commercial, community-owned, non-profit, or otherwise privately owned. Internet services typically provided by ISPs can include internet access, internet transit, domain name registration, web hosting, and colocation. History The Internet (originally ARPAnet) was developed as a network between government research laboratories and participating departments of universities. Other companies and organizations joined by direct connection to the backbone, or by arrangements through other connected companies, sometimes using dialup tools such as UUCP. By the late 1980s, a process was set in place towards public, commercial use of the Internet. Some restrictions were removed by 1991, shortly after the introduction of the World Wide Web. During the 1980s, online s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunications Tariff
A telecommunications tariff is an open contract between a telecommunications service provider and the public, filed with a regulating body such as state and municipal Public Utilities Commissions and federal entities such as the Federal Communications Commission (FCC). Such tariffs outline the terms and conditions of providing telecommunications service to the public including rates, fees, and charges. Reasons for tariffs At a minimum, tariffs imposed must cover the cost of providing the service to the consumer. The consumer may be the final user or an intermediary such as a service provider. If a telecommunications operator cannot recover its costs, it will make a loss and the company will go bankrupt. Tariffs must also be used to cover maintenance, additional research and other indirect costs associated with providing the service. However, telecommunications service providers must be careful not to over-price each service, as prices have a direct influence on demand for that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Access
Data access is a generic term referring to a process which has both an IT-specific meaning and other connotations involving access rights in a broader legal and/or political sense. In the former it typically refers to software and activities related to storing, retrieving, or acting on data housed in a database or other information repository, repository. Details Two fundamental types of data access exist: # sequential access (as in magnetic tape data storage, magnetic tape, for example) # random access (as in indexed digital media, media) Data access crucially involves authorization to access different data repositories. Data access can help distinguish the abilities of administrators and users. For example, administrators may have the ability to remove, edit and add data, while general users may not even have "read" rights if they lack access to particular information. Historically, each repository (including each different database, file system, etc.), might require the use of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
