The Radio Telephone Network C, was a first generation analog cellular phone system deployed and operated in Germany by DeTeMobil. It utilized the C450 standard and was the third and last update of a series of analog mobile phone systems used within Germany, superseding the B-Netz and the A-Netz before it, it has been replaced by both the newer D-Netz and E-Netz systems. The C-Netz was introduced in 1985 to replace the existing B-Netz/B2-Netz system used in Germany at the time. Due to problems with the B-Netz mobile networks, early adoption of C-Netz was high in rural areas which had lacked prior B-Netz coverage. However, like other first-generation analog systems, it suffered from poor call quality and was susceptible to eavesdropping; the system was built up in West Germany and West Berlin, but following German reunification in 1990, was built up in the new German states. By December 1988, the service had grown to nearly 100,000 customers, reached a peak user base of around 800,000 in the early 1990s.
It remained popular throughout the decade as a preferred system for mobile car phones rural taxi services, where it enjoyed an advantage in reception. However, it was inferior in all other ways to the newer GSM networks, by the late 1990s Deutsche Telekom stopped accepting new customers, its user base dropped rapidly. The C-Netz service was shut down on December 31, 2000; some cells near the German-Dutch border remained active for several more months but were discontinued as well. The C-Netz radio spectrum in Germany was reallocated for use with Flarion's Flash-OFDM mobile networking standard which launched in 2005, it was used to service Germany's rail service with Internet connectivity under the name Railnet. The C450 standard was developed by Siemens in 1980, it is a 1G analog cellular standard that utilized non-audible in-band signaling, audio scrambling via band-inversion and cell network call queuing when congested. Cellular nodes varied in size, supporting a primary cell size of 15-20 km and micro-cells of 2-3 km in size.
Channel bandwidth was 20 kHz, although it could be operated in a narrow-band mode of only 12 kHz. As its name implies, it was designed for the 450 MHz UHF frequency range; the C-Netz's C450 standard was a heterogeneous cellular system. France used the RadioCom 2000 analog standard while Sweden, the Netherlands and Switzerland used the NMT analog standard in the 450 or 900 MHz bands. Austria's own C-Netz system utilized the NMT standard, not C450; this differs from previous systems used in Austria. A-Netz B-Netz D-Netz E-Netz
AT&T Mobility LLC known as AT&T Wireless, marketed as AT&T, is a wholly owned subsidiary of AT&T Inc. that provides wireless services to 153 million subscribers in the United States including Puerto Rico and the U. S. Virgin Islands. AT&T Mobility is the second largest wireless telecommunications provider in the United States and Puerto Rico behind Verizon Wireless and the largest wireless telecommunications provider in North America when including AT&T Mexico. Known as Cingular Wireless from 2000 to 2007, a joint venture between SBC Communications and BellSouth, the company acquired the old AT&T Wireless in 2004. In January 2007, Cingular confirmed. Although the legal corporate name change occurred for both regulatory and brand-awareness reasons both brands were used in the company's signage and advertising during a transition period; the transition concluded in late June, just prior to the rollout of the Apple iPhone. On March 20, 2011, AT&T Mobility announced its intention to acquire T-Mobile USA from Deutsche Telekom for $39 billion.
If it had received government and regulatory approval, AT&T would have had more than 130 million subscribers. However, the U. S. Department of Justice, the Federal Communications Commission, AT&T Mobility's competitors opposed the move on the grounds that it would reduce competition in the cellular network market. In December 2011, in the face of both governmental and widespread consumer opposition, AT&T withdrew its offer to complete the merger. Customers can choose to have one of the AT&T's Mobile Share Unlimited plans; as of January 8, 2016 AT&T no longer offers 2 year contracts for subsidized smart phones to its consumer customers. Customers who have 2 year contracts are grandfathered, until they upgrade to a new device they will have to choose from AT&T's NEXT installment plans for smartphones. AT&T reintroduced unlimited data plans for its customers who have either AT&T U-verse or AT&T's DirecTV. Unlimited data plans may be speed throttled. On the TV requirement was dropped for the Unlimited Plan followed by the introduction of the new Unlimited Plus and Choice plan series.
The new Unlimited Plans come with Entertainment perks for DirecTV, Uverse TV and DirecTV Now customers. With the inclusion of these new plans AT&T has introduced a free roaming in Mexico for its postpaid customers on select Mobile Share Plans and free Canada and Mexico roaming on Unlimited Plans. On May 21, 2018 AT&T dropped its roaming restrictions on the Unlimited Plans allowing customer to roam in Canada and Mexico without limits. AT&T allows existing customers to stay on legacy right plans. Within AT&T's 21-state landline footprint, other AT&T services are offered at the AT&T retail stores, including signing up for home phone, U-verse. AT&T stores outside of its footprint offer wireless services. All AT&T company-owned stores nationwide sell DirecTV. A large number of AT&T Mobility employees are unionized, belonging to the Communications Workers of America; the CWA represented 15,000 of the previous 20,000 AT&T Wireless employees as of early 2006. As of the end of 2009, the CWA website claims 40,000 workers of AT&T Mobility are represented by the union.
Cingular Wireless was founded in 2000 as a joint venture of SBC Communications and BellSouth. The joint venture created the nation's second-largest carrier. Cingular grew out of a conglomeration of more than 100 companies, with 12 well-known regional companies with Bell roots; the 12 companies included: Three companies spun off from Advanced Mobile Phone Service Ameritech Mobile Communications BellSouth Mobility Southwestern Bell Mobile Systems BellSouth Mobility DCS BellSouth Wireless Data CCPR Services d/b/a Cellular One of Puerto Rico and U. S. Virgin Islands Pacific Bell Wireless Pacific Bell Wireless Northwest SBC Wireless SNET Mobility Southwestern Bell WirelessSBC Wireless had operated in several northeast markets under the "Cellular One" brand, while BellSouth's wireless operations incorporated the former Houston Cellular. Cingular's lineage can be traced back to Advanced Mobile Phone Service, a subsidiary of AT&T created in 1978 to provide cellular service nationwide. AMPS was divided among the Regional Bell Operating Companies as part of the Bell System divestiture.
With the exception of Pacific Bell and BellSouth Mobility DCS, the digital network consisted of D-AMPS technology. The Pacific Bell and BellSouth Mobility DCS networks used GSM technology on the PCS frequency band. In October 2007, AT&T's president and chief executive officer Stan Sigman announced his retirement. Ralph de la Vega, group president-Regional Telecom & Entertainment, was named as president and CEO of AT&T Mobility. In February 2004, after a bidding war with Britain's Vodafone Plc Cingular announced that it would purchase its struggling competitor, AT&T Wireless Services, for $41 billion This was more than twice the company's trading value; the merger was completed on October 26, 2004. The combined company had a customer base of 46 million people at the time, making Cingular the largest wireless provider in the United States. AT&T Wireless was legally renamed New Cingular Wireless Services. Shortly after, new commercials were shown with the "AT&T" transforming into the Cingular logo, with the Cingular logo's text turned blue to acknowledge the change.
Some of the companies that co
Telemetry is an automated communications process by which measurements and other data are collected at remote or inaccessible points and transmitted to receiving equipment for monitoring. The word is derived from Greek roots: tele = remote, metron = measure. Systems that need external instructions and data to operate require the counterpart of telemetry, telecommand. Although the term refers to wireless data transfer mechanisms, it encompasses data transferred over other media such as a telephone or computer network, optical link or other wired communications like power line carriers. Many modern telemetry systems take advantage of the low cost and ubiquity of GSM networks by using SMS to receive and transmit telemetry data. A telemeter is a device used to remotely measure any quantity, it consists of a sensor, a transmission path, a display, recording, or control device. Telemeters are the physical devices used in telemetry. Electronic devices are used in telemetry and can be wireless or hard-wired, analog or digital.
Other technologies are possible, such as mechanical and optical. Telemetry may be commutated to allow. Telemetering information over wire had its origins in the 19th century. One of the first data-transmission circuits was developed in 1845 between the Russian Tsar's Winter Palace and army headquarters. In 1874, French engineers built a system of weather and snow-depth sensors on Mont Blanc that transmitted real-time information to Paris. In 1901 the American inventor C. Michalke patented the selsyn, a circuit for sending synchronized rotation information over a distance. In 1906 a set of seismic stations were built with telemetering to the Pulkovo Observatory in Russia. In 1912, Commonwealth Edison developed a system of telemetry to monitor electrical loads on its power grid; the Panama Canal used extensive telemetry systems to monitor locks and water levels. Wireless telemetry made early appearances in the radiosonde, developed concurrently in 1930 by Robert Bureau in France and Pavel Molchanov in Russia.
Molchanov's system modulated temperature and pressure measurements by converting them to wireless Morse code. The German V-2 rocket used a system of primitive multiplexed radio signals called "Messina" to report four rocket parameters, but it was so unreliable that Wernher von Braun once claimed it was more useful to watch the rocket through binoculars. In the US and the USSR, the Messina system was replaced with better systems. Early Soviet missile and space telemetry systems which were developed in the late 1940s used either pulse-position modulation or pulse-duration modulation. In the United States, early work employed similar systems, but were replaced by pulse-code modulation. Soviet interplanetary probes used redundant radio systems, transmitting telemetry by PCM on a decimeter band and PPM on a centimeter band. Telemetry has been used by weather balloons for transmitting meteorological data since 1920. Telemetry is used to transmit drilling mechanics and formation evaluation information uphole, in real time, as a well is drilled.
These services are known as Measurement while Logging while drilling. Information acquired thousands of feet below ground, while drilling, is sent through the drilling hole to the surface sensors and the demodulation software; the pressure wave is translated into useful information after noise filters. This information is used for Formation evaluation, Drilling Optimization, Geosteering. Telemetry is a key factor in modern motor racing, allowing race engineers to interpret data collected during a test or race and use it to properly tune the car for optimum performance. Systems used in series such as Formula One have become advanced to the point where the potential lap time of the car can be calculated, this time is what the driver is expected to meet. Examples of measurements on a race car include accelerations in three axes, temperature readings, wheel speed, suspension displacement. In Formula One, driver input is recorded so the team can assess driver performance and the FIA can determine or rule out driver error as a possible cause.
Developments include two-way telemetry which allows engineers to update calibrations on the car in real time. In Formula One, two-way telemetry surfaced in the early 1990s and consisted of a message display on the dashboard which the team could update, its development continued until May 2001. By 2002, teams were able to change engine mapping and deactivate engine sensors from the pit while the car was on the track. For the 2003 season, the FIA banned two-way telemetry from Formula One. Telemetry has been applied in yacht racing on Oracle Racing's USA 76. One way telemetry system has been applied in R/C racing car to get information by car's sensors like: engine RPM, temperatures, throttle. In the transportation industry, telemetry provides meaningful information about a vehicle or driver's performance by collecting data from sensors within the vehicle; this is undertaken for various reasons ranging from staff compliance monitoring, insurance rating to predictive maintenance. Telemetry is used to link traffic counter devices to data recorders to measure traffic flows and vehicle lengths and weights.
Most activities related to healthy crops and good yi
The Universal Mobile Telecommunications System is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP, UMTS is a component of the International Telecommunications Union IMT-2000 standard set and compares with the CDMA2000 standard set for networks based on the competing cdmaOne technology. UMTS uses wideband code division multiple access radio access technology to offer greater spectral efficiency and bandwidth to mobile network operators. UMTS specifies a complete network system, which includes the radio access network, the core network and the authentication of users via SIM cards; the technology described in UMTS is sometimes referred to as Freedom of Mobile Multimedia Access or 3GSM. Unlike EDGE and CDMA2000, UMTS requires new base stations and new frequency allocations. UMTS supports maximum theoretical data transfer rates of 42 Mbit/s when Evolved HSPA is implemented in the network. Users in deployed networks can expect a transfer rate of up to 384 kbit/s for Release'99 handsets, 7.2 Mbit/s for High-Speed Downlink Packet Access handsets in the downlink connection.
These speeds are faster than the 9.6 kbit/s of a single GSM error-corrected circuit switched data channel, multiple 9.6 kbit/s channels in High-Speed Circuit-Switched Data and 14.4 kbit/s for CDMAOne channels. Since 2006, UMTS networks in many countries have been or are in the process of being upgraded with High-Speed Downlink Packet Access, sometimes known as 3.5G. HSDPA enables downlink transfer speeds of up to 21 Mbit/s. Work is progressing on improving the uplink transfer speed with the High-Speed Uplink Packet Access. Longer term, the 3GPP Long Term Evolution project plans to move UMTS to 4G speeds of 100 Mbit/s down and 50 Mbit/s up, using a next generation air interface technology based upon orthogonal frequency-division multiplexing; the first national consumer UMTS networks launched in 2002 with a heavy emphasis on telco-provided mobile applications such as mobile TV and video calling. The high data speeds of UMTS are now most utilised for Internet access: experience in Japan and elsewhere has shown that user demand for video calls is not high, telco-provided audio/video content has declined in popularity in favour of high-speed access to the World Wide Web—either directly on a handset or connected to a computer via Wi-Fi, Bluetooth or USB.
UMTS combines three different terrestrial air interfaces, GSM's Mobile Application Part core, the GSM family of speech codecs. The air interfaces are called UMTS Terrestrial Radio Access. All air interface options are part of ITU's IMT-2000. In the most popular variant for cellular mobile telephones, W-CDMA is used, it is called "Uu interface", as it links User Equipment to the UMTS Terrestrial Radio Access Network Please note that the terms W-CDMA, TD-CDMA and TD-SCDMA are misleading. While they suggest covering just a channel access method, they are the common names for the whole air interface standards. W-CDMA or WCDMA, along with UMTS-FDD, UTRA-FDD, or IMT-2000 CDMA Direct Spread is an air interface standard found in 3G mobile telecommunications networks, it supports conventional cellular voice, text and MMS services, but can carry data at high speeds, allowing mobile operators to deliver higher bandwidth applications including streaming and broadband Internet access. W-CDMA uses the DS-CDMA channel access method with a pair of 5 MHz wide channels.
In contrast, the competing CDMA2000 system uses one or more available 1.25 MHz channels for each direction of communication. W-CDMA systems are criticized for their large spectrum usage, which delayed deployment in countries that acted slowly in allocating new frequencies for 3G services; the specific frequency bands defined by the UMTS standard are 1885–2025 MHz for the mobile-to-base and 2110–2200 MHz for the base-to-mobile. In the US, 1710–1755 MHz and 2110–2155 MHz are used instead, as the 1900 MHz band was used. While UMTS2100 is the most deployed UMTS band, some countries' UMTS operators use the 850 MHz and/or 1900 MHz bands, notably in the US by AT&T Mobility, New Zealand by Telecom New Zealand on the XT Mobile Network and in Australia by Telstra on the Next G network; some carriers such as T-Mobile use band numbers to identify the UMTS frequencies. For example, Band I, Band IV, Band V. UMTS-FDD is an acronym for Universal Mobile Telecommunications System - frequency-division duplexing and a 3GPP standardized version of UMTS networks that makes use of frequency-division duplexing for duplexing over an UMTS Terrestrial Radio Access air interface.
W-CDMA is the basis of Japan's NTT DoCoMo's FOMA service and the most-commonly used member of the Universal Mobile Telecommunications System family and sometimes used as a synonym for UMTS. It uses the DS-CDMA channel access method and the FDD duplexing method to achieve higher speeds and support more users compared to most used time division multiple access and time division duplex schemes. While not an evolutionary upgrade on the airside, it uses the same core network as the 2G GSM networks deployed worldwide, allowing dual mode mobile operation al
Evolution-Data Optimized is a telecommunications standard for the wireless transmission of data through radio signals for broadband Internet access. EV-DO is an evolution of the CDMA2000 standard which supports high data rates and can be deployed alongside a wireless carrier's voice services, it uses advanced multiplexing techniques including code division multiple access as well as time division multiplexing to maximize throughput. It is a part of the CDMA2000 family of standards and has been adopted by many mobile phone service providers around the world those employing CDMA networks, it is used on the Globalstar satellite phone network. EV-DO service has been or will be discontinued in much of Canada in 2015. An EV-DO channel has a bandwidth of 1.25 MHz, the same bandwidth size that IS-95A and IS-2000 use, though the channel structure is different. The back-end network is packet-based, is not constrained by restrictions present on a circuit switched network; the EV-DO feature of CDMA2000 networks provides access to mobile devices with forward link air interface speeds of up to 2.4 Mbit/s with Rel. 0 and up to 3.1 Mbit/s with Rev. A.
The reverse link rate for Rel. 0 can operate up to 153 kbit/s, while Rev. A can operate at up to 1.8 Mbit/s. It was designed to be operated end-to-end as an IP based network, can support any application which can operate on such a network and bit rate constraints. There have been several revisions of the standard, starting with Release 0; this was expanded upon with Revision A to support Quality of Service and higher rates on the forward and reverse link. In late 2006, Revision B was published, whose features include the ability to bundle multiple carriers to achieve higher rates and lower latencies; the upgrade from EV-DO Rev. A to Rev. B involves a software update of the cell site modem, additional equipment for new EV-DO carriers. Existing cdma2000 operators may have to retune some of their existing 1xRTT channels to other frequencies, as Rev. B requires all DO carriers be within 5 MHz; the initial design of EV-DO was developed by Qualcomm in 1999 to meet IMT-2000 requirements for a greater-than-2Mbit/s down link for stationary communications, as opposed to mobile communication.
The standard was called High Data Rate, but was renamed to 1xEV-DO after it was ratified by the International Telecommunication Union under the designation TIA-856. 1xEV-DO stood for "1x Evolution-Data Only", referring to its being a direct evolution of the 1x air interface standard, with its channels carrying only data traffic. The title of the 1xEV-DO standard document is "cdma2000 High Rate Packet Data Air Interface Specification", as cdma2000 is another name for the 1x standard, numerically designated as TIA-2000. Due to possible negative connotations of the word "only", the "DO"-part of the standard's name 1xEV-DO was changed to stand for "Data Optimized", the full name - EV-DO now stands for "Evolution-Data Optimized." The 1x prefix has been dropped by many of the major carriers, is marketed as EV-DO. This provides a more market-friendly emphasis of the technology being data-optimized; the primary characteristic that differentiates an EV-DO channel from a 1xRTT channel is that it is time multiplexed on the forward link.
This means that a single mobile has full use of the forward traffic channel within a particular geographic area during a given slot of time. Using this technique, EV-DO is able to modulate each user’s time slot independently; this allows the service of users in favorable RF conditions with complex modulation techniques while serving users in poor RF conditions with simpler. The forward channel is divided into each being 1.667 ms long. In addition to user traffic, overhead channels are interlaced into the stream, which include the'pilot', which helps the mobile find and identify the channel, the Media Access Channel which tells the mobile devices when their data is scheduled, the'control channel', which contains other information the network needs the mobile devices to know; the modulation to be used to communicate with a given mobile unit is determined by the mobile device itself. It communicates this information back to the serving sector in the form of an integer between 1 and 12 on the "Digital Rate Control" channel.
Alternatively, the mobile can select a "null" rate, indicating that the mobile either cannot decode data at any rate, or that it is attempting to hand off to another serving sector. The DRC values are as follows: Another important aspect of the EV-DO forward link channel is the scheduler; the scheduler most used is called "proportional fair". It's designed to maximize sector throughput while guaranteeing each user a certain minimum level of service; the idea is to schedule mobiles reporting higher DRC indices more with the hope that those reporting worse conditions will improve in time. The system incorporates Incremental Redundancy Hybrid ARQ; each sub-packet of a multi-slot transmission is a turbo-coded replica of the original data bits. This allows mobiles to acknowledge a packet. For example, if a mobile transmits a DRC index of 3 and is scheduled to receive data
Personal Handy-phone System
The Personal Handy-phone System marketed as the Personal Communication Telephone in Thailand, the Personal Access System and commercially branded as Xiaolingtong in Mainland China, is a mobile network system operating in the 1880–1930 MHz frequency band, used in Japan, China and some other Asian countries and regions. PHS is a cordless telephone like DECT, with the capability to handover from one cell to another. PHS cells are small, with transmission power of base station a maximum of 500 mW and range measures in tens or at most hundreds of metres, contrary to the multi-kilometre ranges of CDMA and GSM; this makes PHS suitable for dense urban areas, but impractical for rural areas, the small cell size makes it difficult if not impossible to make calls from moving vehicles. PHS uses TDMA/TDD for its radio channel access method, 32 kbit/s ADPCM for its voice codec. Modern PHS phone can support many value-added services such as high speed wireless data/Internet connection, WWW access, e-mailing, text messaging.
PHS technology is a popular option for providing a wireless local loop, where it is used for bridging the "last mile" gap between the POTS network and the subscriber's home. It was developed under the concept of providing a wireless front-end of an ISDN network, thus a PHS base station is compatible with ISDN and is connected directly to ISDN telephone exchange equipment e.g. a digital switch. In spite of its low-cost base station, micro-cellular system and "Dynamic Cell Assignment" system, PHS offers higher number-of-digits frequency use efficiency with lower cost, compared with typical 3G cellular telephone systems, it enables flat-rate wireless service such as AIR-EDGE, throughout Japan. The speed of an AIR-EDGE data connection is accelerated by combining lines, each of, 32 kbit/s; the first version of AIR-EDGE, introduced in 2001, provided 32 kbit/s service. In 2002, 128 kbit/s service started and in 2005, 256 kbit/s service started. In 2006, the speed of each line was upgraded to 1.6 times with the introduction of "W-OAM" technology.
The speed of AIR-EDGE 8× is up to 402 kbit/s with the latest "W-OAM" capable instrument. In April 2007, "W-OAM typeG" was introduced allowing data speeds of 512 kbit/s for AIR-EDGE 8x users. Furthermore, the "W-OAM typeG" 8× service was planned to be upgraded to a maximum throughput of 800 kbit/s, when the upgrading for access points in its system are completed, thus it was expected to exceed the speeds of popular W-CDMA 3G service like NTT DoCoMo's FOMA in Japan. Developed by NTT Laboratory in Japan in 1989 and far simpler to implement and deploy than competing systems like PDC or GSM, the commercial services were started by three PHS operators in Japan in 1995, forming the PIAF. However, the service was pejoratively dubbed as the "poor man's cellular", due to its limited range and roaming abilities. Market share in Japan has been declining and NTT DoCoMo, which has absorbed NTT Personal, ASTEL terminated the PHS service in January 2008. Most other countries with PHS networks have terminated offering PHS services and migrated to GSM.
In Thailand, TelecomAsia integrated the PHS system with Intelligent Network and marketed the service as Personal Communication Telephone. The integrated system was the world's first that allowed the fixed line telephone subscribers of the public switched telephone network to use PHS as a value added service with the same telephone number and shared the same voice mailbox; the PCT service was commercially launched in November 1999 with the peak of 670,000 subscribers in 2001. However, the number of subscribers had declined to 470,000 in 2005 before the breakeven in 2006 after six years of heavy investment up to 15 billion THB. With the popularity of other cellular phone services, the company shifted the focus of the PCT to a niche market segment of youths ages 10-18. Wireless local loop systems based on PHS technology are in use in some of the above-mentioned countries. WILLCOM DDI-Pocket, introduced flat-rate wireless network and flat-rate calling in Japan, which reversed the local fate of PHS up to an extent.
In China, there was an explosive expansion of subscribers until around 2005. In Chile, Telefónica del Sur launched a PHS-based telephony service in some cities of the southern part of the country in March 2006. In Brazil, Suporte Tecnologia has a PHS-based telephony service in Betim, state of Minas Gerais, Transit Telecom announced a rollout of a PHS network in 2007. China Telecom operated a PAS system in China, although technically it was not regarded as allowed to provide mobile services, because of some particularities of the Chinese governance. China Netcom, the other fixed-line operator in China provides Xiaolingtong service; the system was a runaway hit, with over 90 million subscribers signed up as of 2007. However, low priced mobile phones replaced PHS; the Ministry of Industry and Information Technology of the People's Republic of China issued notices on 13 February 2009 that both registration of new users and expansion of the network were to be discontinued, with the service to be ended by the end of 2011.
A PHS global roaming service was available between Japan and Thailand. This is a list of commercial PHS deployments around the world: PHS-enabled PCMCIA/CompactFlash cards include: TDK DF56CF NTT DoCoMo P-in Comp@ct NTT DoCoMo P-in m@ster NTT DoCoMo P-in memory DDI AirH”Ca