Telus Corporation is a Canadian national telecommunications company that provides a wide range of telecommunications products and services including internet access, entertainment, video, IPTV television. The company is based in the British Columbia area. Telus' wireless division, Telus Mobility, offers HSPA+, LTE-based mobile phone networks. Telus is the incumbent local exchange carrier in British Alberta. Telus' primary competitors are Shaw Communications, Bell Canada and Vidéotron. Telus is a member of the British Columbia Technology Industry Association. Telus was formed in 1990 by the government of Alberta as Telus Communications, a holding company in order to facilitate the privatization of the Alberta Government Telephones Commission, a crown corporation that provided telephone service to most of Alberta outside of Edmonton. In 1995, it acquired Edmonton Telephones Corporation, the main telephone provider for Edmonton itself, from the City of Edmonton. Making Telus the sole provider of telephone service in Alberta.
In 1996, Telus was introduced to the public as the consumer brand, replacing both EdTel. In 1998, Telus and BCTel announced a proposed merger; the merger was completed in 1999. While Telus was the nominal survivor, the merged company moved its headquarters from Edmonton to Vancouver; the corporate name was altered to the present Telus Corporation. The merger created Canada's second largest telcom, with 22% of market share compared to Bell Canada's 42%. Large swaths of rural Quebec the Gaspé Peninsula and the north shore, were served from 1927 by an entity known as Corporation de Téléphone et de Pouvoir de Québec, in 1955, this became known as Québec Téléphone. In 1966, the Anglo-Canadian Telephone Company, a subsidiary of General Telephone and Electronics of Stamford, became a majority shareholder in Québec Téléphone. Anglo-Canadian owned BCTel, GTE owned services in Barbados, Dominican Republic and Trinidad and Tobago. In 1997, Groupe QuébecTel was established to own Québec Téléphone. Following the merger of BCTel with Telus of Alberta, GTE sold its interests in Québec Téléphone to Telusin August 2000, which renamed it Telus Québec on April 2, 2001.
In late 2004, American telecom Verizon Communications sold its 20.5% stake in Telus. This was. Telus is rolling out its next generation fibre optic network, will have invested more than $51 billion in British Columbia alone between 2000–2019. After the Telus-BCTel merger, unionized employees voted to certify the Telecommunications Workers Union as the sole bargaining agent for the expanded company's workforce; the TWU had been the union representing BCTel employees – it replaced the International Brotherhood of Electrical Workers in Alberta. A labour dispute between Telus and the TWU began after the previous contract, negotiated with BCTel before the Telus merger, expired at the end of 2000. After Telus made its final offer to the TWU it informed the union of its intention to bring an end to the dispute by unilaterally implementing its April 2005 offer to employees in Alberta and British Columbia; the next day the union went on strike, although the union referred to the dispute as a "lockout."
On July 25, 2005, Telus blocked its Internet subscribers from accessing a website supporting striking union members. The company expressed concerns over content on the site, saying it identified employees crossing picket lines and encouraged disruptive behaviour, while the union alleged it amounted to censorship; the British Columbia Civil Liberties Association issued an official objection to the unilateral blocking on July 26, stating "Telus is leveraging its power as a telecommunications service provider to censor a specific group, shut down debate and limit the messages conveyed about the current labour dispute". An Alberta court injunction ordered the blocked website, Voices For Change, to remove postings of "Telus employee photos" and other "intimidating or threatening material"; the site owner agreed to comply and Telus unblocked the website. Telus and the TWU ratified a tentative agreement on November 2005, ending the dispute. Telus International is Telus' global arm, providing global contact center and business process outsourcing services to corporations in the financial services, consumer electronics and gaming, telecommunications and utilities industries.
Telus International has contact centers in the Philippines, the United Kingdom, Central America, Eastern Europe, where it is known as Telus International Europe In April 2011, Telus Mobility relaunched the Clearnet brand as a limited market trial in Kelowna, British Columbia, Red Deer, Alberta. The company again closed to new business in June 2012. In February 2013, Telus exchanged all non-voting shares into common shares on a one-for-one basis. In October 2013, Telus acquired minor mobile phone provider Public Mobile and relaunched it in 2015 as a "value brand" MVNO on the Telus network. In October 2008, Telus was named one of British Columbia's Top Employers by Mediacorp Canada Inc., announced by The Vancouver Sun, The Province and the Victoria Times-Colonist. In recent years, the company has been accused of taking actions to hinder the emergence of competition in Canadian telecommunications. This, along with other industry concerns, has led to consumer and industry pressure to reform
Ontario is one of the 13 provinces and territories of Canada and is located in east-central Canada. It is Canada's most populous province accounting for 38.3 percent of the country's population, is the second-largest province in total area. Ontario is fourth-largest jurisdiction in total area when the territories of the Northwest Territories and Nunavut are included, it is home to the nation's capital city and the nation's most populous city, Ontario's provincial capital. Ontario is bordered by the province of Manitoba to the west, Hudson Bay and James Bay to the north, Quebec to the east and northeast, to the south by the U. S. states of Minnesota, Ohio and New York. All of Ontario's 2,700 km border with the United States follows inland waterways: from the west at Lake of the Woods, eastward along the major rivers and lakes of the Great Lakes/Saint Lawrence River drainage system; these are the Rainy River, the Pigeon River, Lake Superior, the St. Marys River, Lake Huron, the St. Clair River, Lake St. Clair, the Detroit River, Lake Erie, the Niagara River, Lake Ontario and along the St. Lawrence River from Kingston, Ontario, to the Quebec boundary just east of Cornwall, Ontario.
There is only about 1 km of land border made up of portages including Height of Land Portage on the Minnesota border. Ontario is sometimes conceptually divided into Northern Ontario and Southern Ontario; the great majority of Ontario's population and arable land is in the south. In contrast, the larger, northern part of Ontario is sparsely populated with cold winters and heavy forestation; the province is named after Lake Ontario, a term thought to be derived from Ontarí:io, a Huron word meaning "great lake", or skanadario, which means "beautiful water" in the Iroquoian languages. Ontario has about 250,000 freshwater lakes; the province consists of three main geographical regions: The thinly populated Canadian Shield in the northwestern and central portions, which comprises over half the land area of Ontario. Although this area does not support agriculture, it is rich in minerals and in part covered by the Central and Midwestern Canadian Shield forests, studded with lakes and rivers. Northern Ontario is subdivided into two sub-regions: Northeastern Ontario.
The unpopulated Hudson Bay Lowlands in the extreme north and northeast swampy and sparsely forested. Southern Ontario, further sub-divided into four regions. Despite the absence of any mountainous terrain in the province, there are large areas of uplands within the Canadian Shield which traverses the province from northwest to southeast and above the Niagara Escarpment which crosses the south; the highest point is Ishpatina Ridge at 693 metres above sea level in Temagami, Northeastern Ontario. In the south, elevations of over 500 m are surpassed near Collingwood, above the Blue Mountains in the Dundalk Highlands and in hilltops near the Madawaska River in Renfrew County; the Carolinian forest zone covers most of the southwestern region of the province. The temperate and fertile Great Lakes-Saint Lawrence Valley in the south is part of the Eastern Great Lakes lowland forests ecoregion where the forest has now been replaced by agriculture and urban development. A well-known geographic feature is part of the Niagara Escarpment.
The Saint Lawrence Seaway allows navigation to and from the Atlantic Ocean as far inland as Thunder Bay in Northwestern Ontario. Northern Ontario occupies 87 percent of the surface area of the province. Point Pelee is a peninsula of Lake Erie in southwestern Ontario, the southernmost extent of Canada's mainland. Pelee Island and Middle Island in Lake Erie extend farther. All are south of 42°N – farther south than the northern border of California; the climate of Ontario varies by location. It is affected by three air sources: cold, arctic air from the north; the effects of these major air masses on temperature and precipitation depend on latitude, proximity to major bodies of water and to a small extent, terrain relief. In general, most of Ontario's climate is classified as humid continental. Ontario has three main climatic regions; the surrounding Great Lakes influence the climatic region of southern Ontario. During the fall and winter months, heat stored from the lakes is released, moderating the climate near the shores of the lakes.
This gives some parts of southern Ontario milder winters than mid-continental areas at lower latitudes. Parts of Southwestern Ontario have a moderate humid continental climate, similar to that of the inland Mid-Atlantic states and the Great Lakes portion of the Midwestern United States; the region has warm to cold winters. Annual precipitation is well distributed throughout the year. Most of this region lies in the lee of the Great Lakes. In December 2010, the snowbelt set a new record when it was h
Amazon.com, Inc. is an American multinational technology company based in Seattle, Washington that focuses in e-commerce, cloud computing, artificial intelligence. Amazon is the largest e-commerce marketplace and cloud computing platform in the world as measured by revenue and market capitalization. Amazon.com was founded by Jeff Bezos on July 5, 1994, started as an online bookstore but diversified to sell video downloads/streaming, MP3 downloads/streaming, audiobook downloads/streaming, video games, apparel, food and jewelry. The company owns a publishing arm, Amazon Publishing, a film and television studio, Amazon Studios, produces consumer electronics lines including Kindle e-readers, Fire tablets, Fire TV, Echo devices, is the world's largest provider of cloud infrastructure services through its AWS subsidiary. Amazon has separate retail websites for some countries and offers international shipping of some of its products to certain other countries. 100 million people subscribe to Amazon Prime.
Amazon is the largest Internet company by revenue in the world and the second largest employer in the United States. In 2015, Amazon surpassed Walmart as the most valuable retailer in the United States by market capitalization. In 2017, Amazon acquired Whole Foods Market for $13.4 billion, which vastly increased Amazon's presence as a brick-and-mortar retailer. The acquisition was interpreted by some as a direct attempt to challenge Walmart's traditional retail stores. In 1994, Jeff Bezos incorporated Amazon. In May 1997, the organization went public; the company began selling music and videos in 1998, at which time it began operations internationally by acquiring online sellers of books in United Kingdom and Germany. The following year, the organization sold video games, consumer electronics, home-improvement items, software and toys in addition to other items. In 2002, the corporation started Amazon Web Services, which provided data on Web site popularity, Internet traffic patterns and other statistics for marketers and developers.
In 2006, the organization grew its AWS portfolio when Elastic Compute Cloud, which rents computer processing power as well as Simple Storage Service, that rents data storage via the Internet, were made available. That same year, the company started Fulfillment by Amazon which managed the inventory of individuals and small companies selling their belongings through the company internet site. In 2012, Amazon bought Kiva Systems to automate its inventory-management business, purchasing Whole Foods Market supermarket chain five years in 2017; as of March 2019, the board of directors is: Jeff Bezos, President, CEO, Chairman Tom Alberg, Managing partner, Madrona Venture Group Rosalind Brewer, Group President, COO, Starbucks Jamie Gorelick, Wilmer Cutler Pickering Hale, Dorr Daniel P. Huttenlocher and Vice Provost, Cornell University Judy McGrath, former CEO, MTV Networks Indra Nooyi, former CEO, PepsiCo Jon Rubinstein, former Chairman, CEO, Inc. Thomas O. Ryder, former Chairman, CEO, Reader's Digest Association Patty Stonesifer, CEO, Martha's Table Wendell P. Weeks, President, CEO, Corning Inc.
In 2000, U. S. toy retailer Toys "R" Us entered into a 10-year agreement with Amazon, valued at $50 million per year plus a cut of sales, under which Toys "R" Us would be the exclusive supplier of toys and baby products on the service, the chain's website would redirect to Amazon's Toys & Games category. In 2004, Toys "R" Us sued Amazon, claiming that because of a perceived lack of variety in Toys "R" Us stock, Amazon had knowingly allowed third-party sellers to offer items on the service in categories that Toys "R" Us had been granted exclusivity. In 2006, a court ruled in favor of Toys "R" Us, giving it the right to unwind its agreement with Amazon and establish its own independent e-commerce website; the company was awarded $51 million in damages. In 2001, Amazon entered into a similar agreement with Borders Group, under which Amazon would co-manage Borders.com as a co-branded service, Borders pulled out of the arrangement in 2007, with plans to launch its own online store. On October 18, 2011, Amazon.com announced a partnership with DC Comics for the exclusive digital rights to many popular comics, including Superman, Green Lantern, The Sandman, Watchmen.
The partnership has caused well-known bookstores like Barnes & Noble to remove these titles from their shelves. In November 2013, Amazon announced a partnership with the United States Postal Service to begin delivering orders on Sundays; the service, included in Amazon's standard shipping rates, initiated in metropolitan areas of Los Angeles and New York because of the high-volume and inability to deliver in a timely way, with plans to expand into Dallas, New Orleans and Phoenix by 2014. In June 2017, Nike confirmed a "pilot" partnership with Amazon to sell goods directly on the platform; as of October 11, 2017, AmazonFresh sells a range of Booths branded products for home delivery in selected areas. In September 2017, Amazon ventured with one of its sellers JV Appario Retail owned by Patni Group which has recorded a total income of US$ 104.44 million in financial year 2017–18. In November 2018, Amazon reached an agreement with Apple Inc. to sell selected products through the service, via the company and selected Apple Authorized Resellers.
As a result of this partnership, only Apple Authorized Resellers may sell Apple products on Amazon effective January 4, 2019. Amazon.com's product lines available at its website include several media, baby products, consumer electronics, beauty products, gourmet food, groceries and perso
A colocation centre or "carrier hotel", is a type of data centre where equipment and bandwidth are available for rental to retail customers. Colocation facilities provide space, power and physical security for the server and networking equipment of other firms and connect them to a variety of telecommunications and network service providers with a minimum of cost and complexity. Many colocation providers sell to a wide range of customers, ranging from large enterprises to small companies; the customer owns the IT equipment and the facility provides power and cooling. Customers retain control over the design and usage of their equipment, but daily management of the data center and facility are overseen by the multi-tenant colocation provider. Cabinets – A cabinet is a locking unit that holds a server rack. In a multi-tenant data center, servers within cabinets share raised-floor space with other tenants, in addition to sharing power and cooling infrastructure. Cages – A cage is dedicated server space within a traditional raised-floor data center.
Cages share power and cooling infrastructure with other data center tenants. Suites – A suite is a dedicated, private server space within a traditional raised-floor data center. Suites may share power and cooling infrastructure with other data center tenants, or have these resources provided on a dedicated basis. Modules – data center modules are purpose-engineered modules and components to offer scalable data center capacity, they use standardized components, which make them added, integrated or retrofitted into existing data centers, cheaper and easier to build. In a colocation environment, the data center module is a data center within a data center, with its own steel walls and security protocol, its own cooling and power infrastructure. "A number of colocation companies have praised the modular approach to data centers to better match customer demand with physical build outs, allow customers to buy a data center as a service, paying only for what they consume." Buildings with data centres inside them are easy to recognize due to the amount of cooling equipment located outside or on the roof.
Colocation facilities have many other special characteristics: Fire protection systems, including passive and active elements, as well as implementation of fire prevention programmes in operations. Smoke detectors are installed to provide early warning of a developing fire by detecting particles generated by smouldering components prior to the development of flame; this allows investigation, interruption of power, manual fire suppression using hand held fire extinguishers before the fire grows to a large size. A fire sprinkler system is provided to control a full scale fire if it develops. Clean agent fire suppression gaseous systems are sometimes installed to suppress a fire earlier than the fire sprinkler system. Passive fire protection elements include the installation of fire walls around the space, so a fire can be restricted to a portion of the facility for a limited time in the event of the failure of the active fire protection systems, or if they are not installed. 19-inch racks for data equipment and servers, 23-inch racks for telecommunications equipment Cabinets and cages for physical access control over tenants' equipment.
Depending on one's needs a cabinet can house multiple racks. Overhead or underfloor cable rack and fibreguide, power cables on separate rack from data Air conditioning is used to control the temperature and humidity in the space. ASHRAE recommends a temperature range and humidity range for optimal electronic equipment conditions versus environmental issues; the electrical power used by the electronic equipment is converted to heat, rejected to the ambient air in the data centre space. Unless the heat is removed, the ambient temperature will rise, resulting in electronic equipment malfunction. By controlling the space air temperature, the server components at the board level are kept within the manufacturer's specified temperature and humidity range. Air conditioning systems help keep equipment space humidity within acceptable parameters by cooling the return space air below the dew point. Too much humidity and water may begin to condense on internal components. In case of a dry atmosphere, ancillary humidification systems may add water vapour to the space if the humidity is too low, to avoid static electricity discharge problems which may damage components.
Low-impedance electrical ground Few, if any, windowsColocation data centres are audited to prove that they live up to certain standards and levels of reliability. For service organizations today, SSAE 16 calls for a description of its "system"; this is far more detailed and comprehensive than SAS 70's description of "controls". Other data center compliance standards include Health Insurance Portability and Accountability Act audit and PCI DSS Standards. Colocation facilities have generators that start automatically when utility power fails running on diesel fuel; these generators may have varying levels of redundancy, depending on. Generators do not start instantaneously, so colocation facilities have battery backup systems. In many facilities, the operator of the facility provides large inverters to provide AC power from the batteries. In other cases, customers may install smaller UPSes in their racks; some customers choose to use equipment
Limelight Networks is an American company that provides a content delivery network service, used for delivery of digital media content and software. As of March 2018, the company's network has more than 80 points-of-presence and delivers between 40-80 petabytes of data daily, with 31+ Terabits per second of egress capacity across the globe. Limelight Networks was founded in 2001 in Tempe, Arizona as a provider of content delivery network services; the Company's Limelight Orchestrate Platform delivers Live and On-Demand video and online content to any connected device anywhere in the world. In July 2006, the company closed a $130 million equity financing round led by Goldman Sachs Capital Partners. Limelight Networks raised $240 million in an initial public offering, during June 2007, selling 16 million shares at $15. In April 2008, company founder Michael Gordon was recognized as a "Streaming Media All-Star" by StreamingMedia Magazine, for his contributions to the industry. Over the years Limelight has received several other awards for its services including, receiving Frost & Sullivan's prestigious award for Product Line Strategy in 2012.
Forrester Research named Limelight a Strong Performer in The Forrester Wave™: Online Video Platforms, Q1 2013. In October 2017 Limelight Networks was recognized on Streaming Media's List of "100 Companies that Matter Most in Online Video" Limelight operates its own private network with more than 31+ terabits per second of global egress capacity as of March 2018; the network consists of dense clusters of specially configured servers in more than 80 delivery locations which are interconnected through the company’s global network and connected to more than 900 Internet service provider networks. Limelight caches web content for its customers in multiple delivery locations around the world, serving it to users from the fastest location. A private fiber network backbone between its delivery locations allows cache-fill traffic and dynamic content to bypass the public internet and improve the delivery speed of content; this architecture is managed by intelligent proprietary software that increases the speed of delivery with fewer cache misses and can scale to handle surges in end-user demand.
The Orchestrate Platform is composed of services including content delivery, video packaging and content management, web acceleration, cloud security, cloud storage. In August 2007, the company announced a technology and services agreement with Microsoft under which Limelight will help improve the performance and reliability of Internet delivery of media content and online services, including video, games and social media, across Microsoft's global Internet properties. In March 2008, the company was the infrastructure provider for the webcast of Oprah's "A New Earth" classroom series, featuring author Eckhart Tolle; the live event drew over 800,000 users. The server crashed during the event because of an error in the programming code. In May 2008, NBC announced that the company would be the content delivery network for the 2008 Summer Olympics webcast on NBCOlympics.com. The company delivered "more than 50 million unique visitors, resulting in 1.3 billion page views, 70 million video streams, 600 million minutes of video watched" for NBCOlympics.com, using Microsoft Silverlight technology.
In June 2008, the company was the primary source of content delivery services for the online debut of Disney's Camp Rock. The 24-hour online event saw more than 863,000 total plays for the movie. In January 2009, the company delivered the inauguration of U. S. President Barack Obama to 2.5 million Internet viewers around the world, resulting in more than 9 million simultaneous multimedia streams overall flowing through the company's network. That year, in March, the company was the exclusive mobile content delivery provider for CBS' coverage of the 2009 NCAA Tournament. Limelight Networks' technology was used to deliver coverage of the college basketball games to the Apple iPhone. In 2012, Limelight helped deliver sporting events like the Wimbledon Tennis Championships, the Indian Cricket League, the European Championship and the RBS Six Nations’ rugby championships and helped several broadcasters deliver the 2012 Summer Games. Described and Captured Media Program, a non profit educational organization uses Limelight Networks to accelerate distribution by caching videos on servers as close to the user as possible.
In February 2017 Limelight was one of three content delivery networks to stream the NFL's Super Bowl. May 2009, the company acquired Kiptronic, Inc. a held provider of device-optimized content delivery solutions and dynamic advertising insertion. It exists today as the Orchestrate Video offering. April 2010, the company acquired EyeWonder, Inc. a held provider of rich media advertising founded in 1999 for $110 million. As part of the purchase of EyeWonder, Limelight Networks, Inc. purchased chors GmbH. Both of these businesses, which consisted of the EyeWonder business unit, were sold to DG. August 2011 the company acquired Delve Networks, Inc. a held provider of cloud-based video publishing and analytics services. It exists today as the Orchestrate Video offering. May 2011, the company acquired AcceloWeb for $20 million, it exists today as the Orchestrate Performance offering. May 2011, the company acquired Clickability, a web content management system company, for $10 million. On December 23, 2013 Upland Software announced.
In June 2006, Limelight Networks was sued by Akamai Technologies and the Massachusetts Institute of Technology over alleged
Cologix, a network neutral interconnection and data center company, provides data center solutions from 24 interconnection locations across 9 North American markets. The edge markets that Cologix operates in are: Ohio; the company supports five Internet exchanges. Cologix acquired DataCenter. BZ in February 2014, procuring 86,000 square feet across two data center facilities at 555 Scherers Court in Columbus, Ohio; the site is located at the intersection of two trunks of nationwide fiber optic network that carries most Internet transmissions. Cologix is building a 160K SQF, 18+MW data center on its existing 8 acre campus in Columbus; the new $130M+ facility will become Columbus’s largest neutral data center and will be directly linked to Cologix’s existing data centers, offering connectivity to 45+ network service providers, 20+ cloud service providers and the Ohio-IX Internet Exchange. The data center is built based on a concurrently maintainable design with N +1 cooling. Further attributes include K-rated perimeter fence and 24x7 guards.
The redundancy, scale and connectivity enables Cologix to address growing market demand ranging from individual cabinets to multi-megawatt deployments. Dallas is situated at the major crossroads of network connectivity in the South Central United States. Cologix operates 40,000 square feet across two data centers in the Dallas Infomart, including a meet-me-room; the Dallas INFOMART building, is the region’s preeminent carrier hotel located at 1950 North Stemmons Freeway. The INFOMART has the largest number of carriers out of any single building in a 900-mile radius, with more than 8,700 strands of fiber. Cologix operates two data centers in Jacksonville, including one site, JAX 1, at 421 West Church Street and a second data center, JAX 2, at 4800 Spring Park Road which provides enterprise colocation and disaster recovery. Cologix maintains a meet-me-room in the 421 West Church Street building, wired with submarine communications cable to connect to Central and South America. Cologix connects the NAP of the Americas in Miami to Cologix's Jacksonville data center and meet-me-room at 421 West Church Street.
The 421 West Church Street site facilitates connections at the intersection of metro, long-haul and subsea fiber routes. Cologix operates 100,000 square feet of data center space in Lakeland, Florida offering disaster recovery and colocation services from their data center. Cologix operates data center space and the meet-me-room at the carrier hotel at the 511 Building in downtown Minneapolis, Minnesota providing access to more than 80+ network providers. Cologix provides the Midwest Internet Cooperative Exchange with space and power in the 511 Building. Cologix’s Northern New Jersey data centers are located about 30 miles outside of Manhattan and 280+ feet above sea level. Cologix operates four New Jersey data centers and business continuity sites, within more than 230,000 SQF of usable floor space, provide enterprise‐grade colocation and managed services. Cologix operates 11 network neutral data centers in Montreal and Vancouver. Cologix operates more than 100,000 square feet of colocation space across seven data centers in Montreal, including in the carrier hotel at 1250 Rene Levesque West.
A dedicated fiber ring connects the seven Cologix Montreal sites to share connectivity. Additionally, the Quebec Internet Exchange deployed a core node with Cologix at 1250 Rene Levesque. Cologix operates two downtown Toronto data centers at 151 Front 905 King West in Toronto; the sites share connectivity through the use of a diverse metro fiber ring. Cologix Toronto offers access to more than 150+ networks and provides a direct on-ramp to the Toronto Internet Exchange. Cologix operates two data centers in Vancouver, British Columbia in the Harbour Centre at 555 West Hastings Street and 1050 West Pender; the Vancouver Internet Exchange, an open and participant-run non-profit Internet exchange, deployed a core node in Cologix's facility at 1050 West Pender Street in Vancouver. Cologix is partnered with VANIX, contributing space and fiber optic network connections
Code-division multiple access
Code-division multiple access is a channel access method used by various radio communication technologies. CDMA is an example of multiple access, where several transmitters can send information over a single communication channel; this allows several users to share a band of frequencies. To permit this without undue interference between the users, CDMA employs spread spectrum technology and a special coding scheme. CDMA is used as the access method in many mobile phone standards. IS-95 called "cdmaOne", its 3G evolution CDMA2000, are simply referred to as "CDMA", but UMTS, the 3G standard used by GSM carriers uses "wideband CDMA", or W-CDMA, as well as TD-CDMA and TD-SCDMA, as its radio technologies; the technology of code-division multiple access channels has long been known. In the Soviet Union, the first work devoted to this subject was published in 1935 by Dmitry Ageev, it was shown that through the use of linear methods, there are three types of signal separation: frequency and compensatory.
The technology of CDMA was used in 1957, when the young military radio engineer Leonid Kupriyanovich in Moscow made an experimental model of a wearable automatic mobile phone, called LK-1 by him, with a base station. LK-1 has a weight of 3 kg, 20–30 km operating distance, 20–30 hours of battery life; the base station, as described by the author, could serve several customers. In 1958, Kupriyanovich made the new experimental "pocket" model of mobile phone; this phone weighed 0.5 kg. To serve more customers, Kupriyanovich proposed the device, which he called "correlator." In 1958, the USSR started the development of the "Altai" national civil mobile phone service for cars, based on the Soviet MRT-1327 standard. The phone system weighed 11 kg, it was placed in the trunk of the vehicles of high-ranking officials and used a standard handset in the passenger compartment. The main developers of the Altai system were VNIIS and GSPI. In 1963 this service started in Moscow, in 1970 Altai service was used in 30 USSR cities.
One of the early applications for code-division multiplexing is in the Global Positioning System. This is distinct from its use in mobile phones; the Qualcomm standard IS-95, marketed as cdmaOne. The Qualcomm standard IS-2000, known as CDMA2000, is used by several mobile phone companies, including the Globalstar network; the UMTS 3G mobile phone standard, which uses W-CDMA. CDMA has been used in the OmniTRACS satellite system for transportation logistics. CDMA is a spread-spectrum multiple-access technique. A spread-spectrum technique spreads the bandwidth of the data uniformly for the same transmitted power. A spreading code is a pseudo-random code that has a narrow ambiguity function, unlike other narrow pulse codes. In CDMA a locally generated code runs at a much higher rate than the data to be transmitted. Data for transmission is combined by bitwise XOR with the faster code; the figure shows. The data signal with pulse duration of T b is XORed with the code signal with pulse duration of T c. Therefore, the bandwidth of the data signal is 1 / T b and the bandwidth of the spread spectrum signal is 1 / T c.
Since T c is much smaller than T b, the bandwidth of the spread-spectrum signal is much larger than the bandwidth of the original signal. The ratio T b / T c is called the spreading factor or processing gain and determines to a certain extent the upper limit of the total number of users supported by a base station; each user in a CDMA system uses a different code to modulate their signal. Choosing the codes used to modulate the signal is important in the performance of CDMA systems; the best performance occurs when there is good separation between the signal of a desired user and the signals of other users. The separation of the signals is made by correlating the received signal with the locally generated code of the desired user. If the signal matches the desired user's code the correlation function will be high and the system can extract that signal. If the desired user's code has nothing in common with the signal, the correlation should be as close to zero as possible. If the code is correlated with the signal at any time offset other than zero, the correlation should be as close to zero as possible.
This is used to reject multi-path interference. An analogy to the problem of multiple access is a room in which people wish to talk to each other simultaneously. To avoid confusion, people could take turns speaking, speak at different pitches, or speak in different languages. CDMA is analogous to the last example where people speaking the same language can understand each other, but other languages are perceived as noise and rejected. In radio CDMA, each group of users is given a shared code. Many codes occupy the same channel, but only users associated