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105-446: The name TDMA is based on the abbreviation for time-division multiple access , a common multiple access technique which is used in most 2G standards, including GSM, as well as in IS-54 and IS-136. D-AMPS competed against GSM and systems based on code-division multiple access (CDMA). D-AMPS uses existing AMPS channels and allows for smooth transition between digital and analog systems in

210-460: A base station this becomes particularly difficult because the mobile phone can move around and vary the timing advance required to make its transmission match the gap in transmission from its peers. Most 2G cellular systems, with the notable exception of IS-95 , are based on TDMA. GSM , D-AMPS , PDC , iDEN , and PHS are examples of TDMA cellular systems. In the GSM system, the synchronization of

315-596: A scheduling algorithm dynamically reserves a variable number of time slots in each frame to variable bit-rate data streams, based on the traffic demand of each data stream. Dynamic TDMA is used in New York City New York , often called New York City or NYC , is the most populous city in the United States , located at the southern tip of New York State on one of the world's largest natural harbors . The city comprises five boroughs , each coextensive with

420-550: A 24.3- kilobaud channel rate and gives an effective 48.6 kbit/s data rate across the six time slots comprising one frame in the 30 kHz channel. AT&T Mobility , the largest US carrier to support D-AMPS (which it refers to as "TDMA"), had turned down its existing network in order to release the spectrum to its GSM and UMTS platforms in 19 wireless markets, which started on May 30, 2007, with other areas that followed in June and July. The TDMA network in these markets operated on

525-460: A cellular system has digital capability, the mobile unit is assigned a digital channel first. If no digital channels are available, the cellular system will assign an analog channel. The transmitter converts the audio signal to a radio frequency (RF), and the receiver converts an RF signal to an audio signal. The antenna focuses and converts RF energy for reception and transmission into free space. The control panel serves as an input/output mechanism for

630-412: A communication system will not be complete without the explanation of a system example. A dual-mode cellular phone as specified by the IS-54 standard is explained. A dual-mode phone is capable of operating in an analog-only cell or a dual-mode cell. Both the transmitter and the receiver support both analog FM and digital time-division multiple access (TDMA) schemes. Digital transmission is preferred, so when

735-612: A decade between Irish immigrants and Black people for work. Rioters burned the Colored Orphan Asylum to the ground. At least 120 people were killed. Eleven Black men were lynched over five days, and the riots forced hundreds of Blacks to flee. The Black population in Manhattan fell below 10,000 by 1865. The White working class had established dominance. It was one of the worst incidents of civil unrest in American history . In 1886,

840-452: A heavier hand-held portable and, even more inconvenient, a shorter time between battery recharges. A conversation's data bits makes up the DATA field. Six slots make up a complete IS-54 frame. DATA in slots 1 and 4, 2 and 5, and 3 and 6 make up a voice circuit. DVCC stands for digital verification color code, arcane terminology for a unique 8-bit code value assigned to each cell. G means guard time,

945-419: A mobile phone to be in communication with up to 6 base stations simultaneously, a type of "same-frequency handover". The incoming packets are compared for quality, and the best one is selected. CDMA's "cell breathing" characteristic, where a terminal on the boundary of two congested cells will be unable to receive a clear signal, can often negate this advantage during peak periods. A disadvantage of TDMA systems

1050-713: A poor security system which allowed people to steal a phone's serial code to use for making illegal calls. All of these triggered the search for a more capable system. The quest resulted in IS-54 , the first American 2G standard. In March 1990, the North American cellular network incorporated the IS-54B standard, the first North American dual mode digital cellular standard. This standard won over Motorola 's Narrowband AMPS or N-AMPS, an analog scheme which increased capacity, by cutting down voice channels from 30 kHz to 10 kHz. IS-54, on

1155-457: A reconstructed speech quality similar to that of the analog AMPS system using frequency modulation. The 7.95-kbit/s signal is then passed through a channel coder that loads the bit rate up to 13 kbit/s. The new half-rate coding standard reduces the overall bit rate for each call to 6.5 kbit/s, and should provide comparable quality to the 13-kbit/s rate. This half-rate gives a channel capacity six times that of analog AMPS. The discussion of

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1260-518: A respective county . The city is the geographical and demographic center of both the Northeast megalopolis and the New York metropolitan area , the largest metropolitan area in the U.S. by both population and urban area . New York is a global center of finance and commerce , culture , technology , entertainment and media , academics and scientific output , the arts and fashion , and, as home to

1365-524: A result of Sandy, and the economic losses in New York City were estimated to be roughly $ 19 billion. The disaster spawned long-term efforts towards infrastructural projects to counter climate change and rising seas, with $ 15 billion in federal funding received through 2022 towards those resiliency efforts. In March 2020, the first case of COVID-19 in the city was confirmed. With its population density and its extensive exposure to global travelers,

1470-419: A specific bit sequence known by all receivers to establish frame alignment. Also, as with GSM, the known sequence acts as a training pattern to initialize an adaptive equalizer. The IS-54 system has different synchronization sequences for each of the six time slots making up the frame, thereby allowing each receiver to synchronize to its own preassigned time slots. An additional 12 bits in every time slot are for

1575-476: A speech denying the request, which was paraphrased on the front page of the New York Daily News as "FORD TO CITY: DROP DEAD." The Municipal Assistance Corporation was formed and granted oversight authority over the city's finances. While a resurgence in the financial industry greatly improved the city's economic health in the 1980s, New York's crime rate continued to increase through that decade and into

1680-402: Is 7C/4 differential quaternary phase shift keying (DQPSK), otherwise known as differential 7t/4 4-PSK or π/4 DQPSK. This technique allows a bit rate of 48.6 kbit/s with 30 kHz channel spacing, to give a bandwidth efficiency of 1.62 bit/s/Hz. This value is 20% better than GSM. The major disadvantage with this type of linear modulation method is the power inefficiency, which translates into

1785-418: Is now used extensively in satellite communications, combat-net radio systems, and passive optical network (PON) networks for upstream traffic from premises to the operator. TDMA is a type of time-division multiplexing (TDM), with the special point that instead of having one transmitter connected to one receiver , there are multiple transmitters. In the case of the uplink from a mobile phone to

1890-405: Is one of the world's most populous megacities . The city and its metropolitan area are the premier gateway for legal immigration to the United States . As many as 800 languages are spoken in New York City, making it the most linguistically diverse city in the world. In 2021, the city was home to nearly 3.1 million residents born outside the U.S., the largest foreign-born population of any city in

1995-432: Is that they create interference at a frequency which is directly connected to the time slot length. This is the buzz which can sometimes be heard if a TDMA phone is left next to a radio or speakers. Another disadvantage is that the "dead time" between time slots limits the potential bandwidth of a TDMA channel. These are implemented in part because of the difficulty in ensuring that different terminals transmit at exactly

2100-506: Is the case in both GSM and IS-136 for example. Exceptions to this include the DECT and Personal Handy-phone System (PHS) micro-cellular systems, UMTS-TDD UMTS variant, and China's TD-SCDMA , which use time-division duplexing, where different time slots are allocated for the base station and handsets on the same frequency. A major advantage of TDMA is that the radio part of the mobile only needs to listen and broadcast for its own time slot. For

2205-473: Is the first mobile communication system which had provision for security, and the first to employ TDMA technology. The evolution of mobile communication began in three different geographic regions: North America , Europe and Japan . The standards used in these regions were quite independent of each other. The earliest mobile or wireless technologies implemented were wholly analogue, and are collectively known as 1st Generation ( 1G ) technologies. In Japan,

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2310-447: Is to maintain connectivity. The slow associated control channel or SACCH does not perform handoffs but conveys things like signal strength information to the base station. The IS-54 speech coder uses the technique called vector sum excited linear prediction (VSELP) coding. This is a special type of speech coder within a large class known as code-excited linear prediction (CELP) coders. The speech coding rate of 7.95 kbit/s achieves

2415-591: The American South . During construction in Foley Square in the 1990s, the African Burying Ground was discovered; the cemetery included 10,000 to 20,000 graves of colonial-era Africans, some enslaved and some free. The 1735 trial and acquittal in Manhattan of John Peter Zenger , who had been accused of seditious libel after criticizing colonial governor William Cosby , helped to establish freedom of

2520-780: The Atlantic port to the agricultural markets and commodities of the North American interior via the Hudson River and the Great Lakes . Local politics became dominated by Tammany Hall , a political machine supported by Irish and German immigrants . In 1831, New York University was founded. Several prominent American literary figures lived in New York during the 1830s and 1840s, including William Cullen Bryant , Washington Irving , Herman Melville , Rufus Wilmot Griswold , John Keese , Nathaniel Parker Willis , and Edgar Allan Poe . Members of

2625-664: The Bill of Rights there. The Supreme Court held its first organizational sessions in New York in 1790. In 1790, for the first time, New York City surpassed Philadelphia as the nation's largest city. At the end of 1790, the national capital was moved to Philadelphia . During the 19th century, New York City's population grew from 60,000 to 3.43 million. Under New York State's gradual emancipation act of 1799, children of slave mothers were to be eventually liberated but to be held in indentured servitude until their mid-to-late twenties. Together with slaves freed by their masters after

2730-697: The Caribbean . The attempt at a peaceful solution to the war took place at the Conference House on Staten Island between American delegates, including Benjamin Franklin , and British general Lord Howe on September 11, 1776. Shortly after the British occupation began, the Great Fire of New York destroyed nearly 500 buildings, about a quarter of the structures in the city, including Trinity Church . In January 1785,

2835-857: The Hudson River , which he named Río de San Antonio ('Saint Anthony's River'). In 1609, the English explorer Henry Hudson rediscovered New York Harbor while searching for the Northwest Passage to the Orient for the Dutch East India Company . He sailed up what the Dutch called North River (now the Hudson River), named first by Hudson as the Mauritius after Maurice, Prince of Orange . Hudson claimed

2940-687: The Lower Hudson Valley . The first documented visit into New York Harbor by a European was in 1524 by explorer Giovanni da Verrazzano . He claimed the area for France and named it Nouvelle Angoulême (New Angoulême ). A Spanish expedition, led by the Portuguese captain Estêvão Gomes sailing for Emperor Charles V , arrived in New York Harbor in January 1525 and charted the mouth of

3045-699: The New York City Fire Department and 71 law enforcement officers. The area was rebuilt with a new World Trade Center , the National September 11 Memorial and Museum , and other new buildings and infrastructure, including the World Trade Center Transportation Hub , the city's third-largest hub. The new One World Trade Center is the tallest skyscraper in the Western Hemisphere and the seventh-tallest building in

3150-503: The Statue of Liberty , a gift from France , was dedicated in New York Harbor. The statue welcomed 14 million immigrants as they came to the U.S. via Ellis Island by ship in the late 19th and early 20th centuries, and is a symbol of the United States and American ideals of liberty and peace. In 1898, the City of New York was formed with the consolidation of Brooklyn (until then a separate city),

3255-683: The Stonewall riots were a series of violent protests by members of the gay community against a police raid that took place in the early morning of June 28, 1969, at the Stonewall Inn in Greenwich Village . They are widely considered to be the single most important event leading to the gay liberation movement and the modern fight for LGBT rights . Wayne R. Dynes , author of the Encyclopedia of Homosexuality , wrote that drag queens were

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3360-580: The United Kingdom , Italy and Ireland ), and TMA-900 (Spanish version of TACS). North American standards were Advanced Mobile Phone System (AMPS) and Narrow-band AMPS (N-AMPS). Despite the Nordic countries ' cooperation, European engineering efforts were divided among the various standards, and the Japanese standards did not get much attention. Developed by Bell Labs in the 1970s and first used commercially in

3465-586: The United States in 1983, AMPS operates in the 800 MHz band in the United States and is the most widely distributed analog cellular standard. (The 1900 MHz PCS band, established in 1994, is for digital operation only.) The success of AMPS kick-started the mobile age in the North America. The market showed an increasing demand because it had higher capacity and mobility than the then-existing mobile communication standards were capable of handling. For example,

3570-575: The headquarters of the United Nations , international diplomacy . With an estimated population in 2023 of 8,258,035 distributed over 300.46 square miles (778.2 km ), the city is the most densely populated major city in the United States. New York City has more than double the population of Los Angeles , the nation's second-most populous city. With more than 20.1 million people in its metropolitan statistical area and 23.5 million in its combined statistical area as of 2020, New York City

3675-586: The steamship General Slocum caught fire in the East River , killing 1,021 people. In 1911, the Triangle Shirtwaist Factory fire , the city's worst industrial disaster, killed 146 garment workers and spurred the growth of the International Ladies' Garment Workers' Union and major improvements in factory safety standards. New York's non-White population was 36,620 in 1890. New York City

3780-411: The 1900 MHz frequency and did not coexist with an AMPS network. Service on the remaining 850 MHz TDMA markets was discontinued along with AMPS service on February 18, 2008, except for in areas where service was provided by Dobson Communications . The Dobson TDMA and AMPS network was shut down March 1, 2008. On May 31, 2007, Rogers Wireless decommissioned its D-AMPS and AMPS networks and moved

3885-525: The 19th century, the city was transformed by both commercial and residential development relating to its status as a national and international trading center , as well as by European immigration, respectively. The city adopted the Commissioners' Plan of 1811 , which expanded the city street grid to encompass almost all of Manhattan. The 1825 completion of the Erie Canal through central New York connected

3990-882: The 1G standards were: Nippon Telegraph and Telephone (NTT) and the high capacity version of it ( Hicap ). The early systems used throughout Europe were not compatible to each other, meaning the later idea of a common 'European Union' viewpoint/technological standard was absent at this time. The various 1G standards in use in Europe included C-Netz (in Germany and Austria), Comviq (in Sweden), Nordic Mobile Telephones /450 (NMT450) and NMT900 (both in Nordic countries), NMT-F (French version of NMT900), TMA-450 (Spanish version of NMT450), Radiocom 2000 (RC2000) (in France), TACS (Total Access Communication System) (in

4095-579: The Bell Labs system in the 1970s could carry only 12 calls at a time throughout all of New York City . AMPS used Frequency Division Multiple Access (FDMA) which enabled each cell site to transmit on different frequencies, allowing many cell sites to be built near each other. AMPS also had many disadvantages, as well. Primarily, it did not have the ability to support the ever-increasing demand for mobile communication usage. Each cell site did not have much capacity for carrying higher numbers of calls. AMPS also had

4200-620: The Continental Army at the Battle of Fort Washington in November 1776 eliminated the last American stronghold in Manhattan, causing George Washington and his forces to retreat across the Hudson River to New Jersey , pursued by British forces. After the battle, in which the Americans were defeated, the British made the city their military and political base of operations in North America. The city

4305-558: The County of New York (which then included parts of the Bronx), the County of Richmond, and the western portion of the County of Queens. The opening of the New York City Subway in 1904, first built as separate private systems, helped bind the new city together. Throughout the first half of the 20th century, the city became a world center for industry, commerce, and communication. In 1904,

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4410-618: The Duke of York (the future King James II and VII). The duke gave part of the colony to proprietors George Carteret and John Berkeley . On August 24, 1673, during the Third Anglo-Dutch War , Anthony Colve of the Dutch navy seized New York at the behest of Cornelis Evertsen the Youngest and rechristened it "New Orange" after William III , the Prince of Orange . The Dutch soon returned

4515-683: The Dutch West India Company had operated as a monopoly in New Netherland, on authority granted by the Dutch States General . In 1639–1640, in an effort to bolster economic growth, the Dutch West India Company relinquished its monopoly over the fur trade, leading to growth in the production and trade of food, timber, tobacco, and slaves (particularly with the Dutch West Indies ). In 1647, Peter Stuyvesant began his tenure as

4620-405: The New York metropolitan area is the largest metropolitan economy in the world , with a gross metropolitan product of over US$ 2.16 trillion. If the New York metropolitan area were its own country , it would have the tenth-largest economy in the world . Despite having a 24/7 rapid transit system , New York also leads the world in urban automobile traffic congestion . The city is home to

4725-699: The Revolutionary War and escaped slaves, a significant free-Black population gradually developed in Manhattan. The New York Manumission Society worked for abolition and established the African Free School to educate Black children. It was not until 1827 that slavery was completely abolished in the state . Free Blacks struggled with discrimination and interracial abolitionist activism continued. New York City's population jumped from 123,706 in 1820 (10,886 of whom were Black and of which 518 were enslaved) to 312,710 by 1840 (16,358 of whom were Black). Also in

4830-507: The SACCH (i.e. system control information). The digital verification color code (DVCC) is the equivalent of the supervisory audio tone used in the AMPS system. There are 256 different 8-bit color codes, which are protected by a (12, 8, 3) Hamming code. Each base station has its own preassigned color code, so any incoming interfering signals from distant cells can be ignored. The modulation scheme for IS-54

4935-415: The air activation and expanded data applications. IS-136 systems needed to support millions of AMPS phones, most of which were designed and manufactured before IS-54 and IS-136 were considered. IS-136 added a number of features to the original IS-54 specification, including text messaging, circuit switched data (CSD), and an improved compression protocol. IS-136 TDMA traffic channels use π/4-DQPSK modulation at

5040-636: The assembly of the Congress of the Confederation made New York City the national capital. New York was the last capital of the U.S. under the Articles of Confederation and the first capital under the Constitution of the United States . As the U.S. capital, New York City hosted the inauguration of the first President, George Washington , and the first Congress , at Federal Hall on Wall Street . Congress drafted

5145-441: The available spectrum, catering to diverse user demands and improving the adaptability of 3G networks to different operational environments. The ITU-T G.hn standard, which provides high-speed local area networking over existing home wiring (power lines, phone lines and coaxial cables) is based on a TDMA scheme. In G.hn , a "master" device allocates "Contention-Free Transmission Opportunities" (CFTXOP) to other "slave" devices in

5250-543: The beginning of the 1990s. By the mid-1990s, crime rates started to drop dramatically due to revised police strategies, improving economic opportunities, gentrification , and new residents, both American transplants and new immigrants from Asia and Latin America. New York City's population exceeded 8 million for the first time in the 2000 United States census ; further records were set in 2010 , and 2020 U.S. censuses. Important new sectors, such as Silicon Alley , emerged in

5355-583: The business elite lobbied for the establishment of Central Park , which in 1857 became the first landscaped park in an American city. The Great Irish Famine brought a large influx of Irish immigrants, of whom more than 200,000 were living in New York by 1860, representing over a quarter of the city's population. Extensive immigration from the German provinces meant that Germans comprised another 25% of New York's population by 1860. Democratic Party candidates were consistently elected to local office, increasing

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5460-409: The call. If an IS-54 signal is detected it gets assigned a digital traffic channel if one is available. The fast associated channel or FACCH performs handoffs during the call, with no need for the mobile to go back to the control channel. In case of high noise, FACCH embedded within the digital traffic channel overrides the voice payload, degrading speech quality to convey control information. The purpose

5565-605: The capacity of AMPS traffic channels. TDMA was initially defined by the IS-54 standard and is now specified in the IS-13x series of specifications of the EIA/TIA. The channel transmission bit rate for digitally modulating the carrier is 48.6 kbit/s. Each frame has six time slots of 6.67-ms duration. Each time slot carries 324 bits of information, of which 260 bits are for the 13-kbit/s full-rate traffic data. The other 64 bits are overhead; 28 of these are for synchronization, and they contain

5670-605: The city from New Jersey. The East River—a tidal strait —flows from Long Island Sound and separates the Bronx and Manhattan from Long Island. The Harlem River , another tidal strait between the East and Hudson rivers, separates most of Manhattan from the Bronx. The Bronx River , which flows through the Bronx and Westchester County , is the only entirely freshwater river in the city. The city's land has been altered substantially by human intervention, with considerable land reclamation along

5775-439: The city rapidly replaced Wuhan , China as the global epicenter of the pandemic during the early phase, straining the city's healthcare infrastructure. Through March 2023, New York City recorded more than 80,000 deaths from COVID-19-related complications. New York City is situated in the northeastern United States , in southeastern New York State, approximately halfway between Washington, D.C. and Boston . Its location at

5880-613: The city's economy. The advent of Y2K was celebrated with fanfare in Times Square . New York City suffered the bulk of the economic damage and largest loss of human life in the aftermath of the September 11, 2001, attacks . Two of the four airliners hijacked that day were flown into the twin towers of the World Trade Center, resulting in the collapse of both buildings and the deaths of 2,753 people, including 343 first responders from

5985-615: The city's ties to the South and its dominant party. In 1861, Mayor Fernando Wood called on the aldermen to declare independence from Albany and the United States after the South seceded, but his proposal was not acted on. Anger at new military conscription laws during the American Civil War (1861–1865), which spared wealthier men who could afford to hire a substitute, led to the Draft Riots of 1863 , whose most visible participants were ethnic Irish working class. The draft riots deteriorated into attacks on New York's elite, followed by attacks on Black New Yorkers after fierce competition for

6090-669: The context of 3G systems, the integration of Time-Division Multiple Access (TDMA) with Code-Division Multiple Access (CDMA) and Time-Division Duplexing (TDD) in the Universal Mobile Telecommunications System (UMTS) represents a sophisticated approach to optimizing spectrum efficiency and network performance. UTRA-FDD (Frequency Division Duplex) employs CDMA and FDD, where separate frequency bands are allocated for uplink and downlink transmissions. This separation minimizes interference and allows for continuous data transmission in both directions, making it suitable for environments with balanced traffic loads. UTRA-TDD (Time Division Duplex), on

6195-417: The development of large housing tracts in eastern Queens and Nassau County , with Wall Street leading America's place as the world's dominant economic power. The United Nations headquarters was completed in 1952, solidifying New York's global geopolitical influence, and the rise of abstract expressionism in the city precipitated New York's displacement of Paris as the center of the art world. In 1969,

6300-418: The early 18th century, New York grew in importance as a trading port while as a part of the colony of New York . It became a center of slavery , with 42% of households enslaving Africans by 1730. Most were domestic slaves ; others were hired out as labor. Slavery became integrally tied to New York's economy through the labor of slaves throughout the port, and the banking and shipping industries trading with

6405-527: The end user; it supports a keypad, a display, a microphone, and a speaker. The coordinator synchronizes the transmission and receives functions of the mobile unit. A dual-mode cellular phone consists of the following: By 1993 American cellular was again running out of capacity, despite a wide movement to IS-54. The American cellular business continued booming. Subscribers grew from one and a half million customers in 1988 to more than thirteen million subscribers in 1993. Room existed for other technologies to cater to

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6510-427: The existing AMPS cellular telephone system, the primary forward and reverse control channels in IS-54 cellular systems use the same signaling techniques and modulation scheme (binary FSK) as AMPS. An AMPS/IS-54 infrastructure can support use of either analog AMPS phones or D-AMPS phones. The access method used for IS-54 is Time Division Multiple Access (TDMA), which was the first U.S. digital standard to be developed. It

6615-461: The former territory of New Netherland , including the city of New Amsterdam , when the Kingdom of England seized it from Dutch control. In the pre-Columbian era , the area of present-day New York City was inhabited by Algonquians , including the Lenape . Their homeland, known as Lenapehoking , included the present-day areas of Staten Island , Manhattan , the Bronx , the western portion of Long Island (including Brooklyn and Queens ), and

6720-479: The growing market. The technologies that followed IS-54 stuck to the digital backbone laid down by it. A pragmatic effort was launched to improve IS-54 that eventually added an extra channel to the IS-54 hybrid design. Unlike IS-54, IS-136 utilizes time-division multiplexing for both voice and control channel transmissions. Digital control channel allows residential and in-building coverage, dramatically increased battery standby time, several messaging applications, over

6825-410: The ice (and its subsequent retreat) contributed to the separation of what is now Long Island and Staten Island. That action left bedrock at a relatively shallow depth, providing a solid foundation for most of Manhattan's skyscrapers. The Hudson River flows through the Hudson Valley into New York Bay . Between New York City and Troy, New York , the river is an estuary . The Hudson River separates

6930-448: The island to England under the Treaty of Westminster of November 1674. Several intertribal wars among the Native Americans and epidemics brought on by contact with the Europeans caused sizeable population losses for the Lenape between 1660 and 1670. By 1700, the Lenape population had diminished to 200. New York experienced several yellow fever epidemics in the 18th century, losing ten percent of its population in 1702 alone. In

7035-599: The last Director-General of New Netherland. During his tenure, the population of New Netherland grew from 2,000 to 8,000. Stuyvesant has been credited with improving law and order; however, he earned a reputation as a despotic leader. He instituted regulations on liquor sales, attempted to assert control over the Dutch Reformed Church , and blocked other religious groups from establishing houses of worship. In 1664, unable to summon any significant resistance, Stuyvesant surrendered New Amsterdam to English troops, led by Colonel Richard Nicolls , without bloodshed. The terms of

7140-545: The local population as a representative of the Dutch colonists. A permanent European presence near New York Harbor was established in 1624, making New York the 12th-oldest continuously occupied European-established settlement in the continental United States , with the founding of a Dutch fur trading settlement on Governors Island . In 1625, construction was started on a citadel and Fort Amsterdam , later called Nieuw Amsterdam (New Amsterdam), on present-day Manhattan Island. The colony of New Amsterdam extended from

7245-420: The mobile phones is achieved by sending timing advance commands from the base station which instruct the mobile phone to transmit earlier and by how much. This compensates for the speed-of-light propagation delay . The mobile phone is not allowed to transmit for its entire time slot; there is a guard interval at the end of each time slot. As the transmission moves into the guard period, the mobile network adjusts

7350-419: The mobile-to-base direction has a 6-bit ramp time to enable its transmitter time to get up to full power, and a 6-bit guard band during which nothing is transmitted. These 12 extra bits in the base-to-mobile direction are reserved for future use. Once a call comes in the mobile switches to a different pair of frequencies; a voice radio channel which the system carrier has made analog or digital. This pair carries

7455-419: The most populous urbanized area in the world in the early 1920s, overtaking London . The metropolitan area surpassed 10 million in the early 1930s, becoming the first megacity . The Great Depression saw the election of reformer Fiorello La Guardia as mayor and the fall of Tammany Hall after eighty years of political dominance. Returning World War II veterans created a post-war economic boom and

7560-544: The mouth of the Hudson River , which feeds into a naturally sheltered harbor and then into the Atlantic Ocean , has helped the city grow in significance as a trading port. Most of the city is built on the three islands of Long Island, Manhattan, and Staten Island. During the Wisconsin glaciation , 75,000 to 11,000 years ago, the New York City area was situated at the edge of a large ice sheet . The erosive forward movement of

7665-421: The network. If the mobile is near the base station, the propagation delay is short and the initiation can succeed. If, however, the mobile phone is just less than 35 km from the base station, the delay will mean the mobile's transmission arrives at the end of the time slot. In this case, the mobile will be instructed to transmit its messages starting nearly a whole time slot earlier so that it can be received at

7770-474: The network. Only one device can use a CFTXOP at a time, thus avoiding collisions. FlexRay protocol which is also a wired network used for safety-critical communication in modern cars, uses the TDMA method for data transmission control. In radio systems, TDMA is usually used alongside frequency-division multiple access (FDMA) and frequency-division duplex (FDD); the combination is referred to as FDMA/TDMA/FDD. This

7875-445: The only " transgender folks around" during the June 1969 Stonewall riots. The transgender community in New York City played a significant role in fighting for LGBT equality. In the 1970s, job losses due to industrial restructuring caused New York City to suffer from economic problems and rising crime rates. Growing fiscal deficits in 1975 led the city to appeal to the federal government for financial aid; President Gerald Ford gave

7980-609: The other hand, combines CDMA with TDMA and TDD. In this scheme, the same frequency band is used for both uplink and downlink, but at different times. This time-based separation is particularly advantageous in scenarios with asymmetric traffic loads, where the data rates for uplink and downlink differ significantly. By dynamically allocating time slots based on demand, UTRA-TDD can efficiently manage varying traffic patterns and enhance overall network capacity. The combination of these technologies in UMTS allows for more flexible and efficient use of

8085-443: The other hand, increased capacity by digital means using TDMA protocols. This method separates calls by time, placing parts of individual conversations on the same frequency, one after the next. TDMA tripled call capacity. Using IS-54, a cellular carrier could convert any of its system's analog voice channels to digital . A dual mode phone uses digital channels where available, and defaults to regular AMPS where they are not. IS-54

8190-424: The period between each time slot. RSVD stands for reserved. SYNC represents synchronization, a critical TDMA data field. Each slot in every frame must be synchronized against all others and a master clock for everything to work. Time slots for the mobile-to-base direction are constructed differently from the base-to-mobile direction. They essentially carry the same information but are arranged differently. Notice that

8295-410: The preceding analog design by dividing each 30 kHz channel pair into three time slots and digitally compressing the voice data, yielding three times the call capacity in a single cell. A digital system also made calls more secure because analog scanners could not access digital signals. The IS-54 standard specifies 84 control channels, 42 of which are shared with AMPS. To maintain compatibility with

8400-697: The press in North America . In 1754, Columbia University was founded. The Stamp Act Congress met in New York in October 1765, as the Sons of Liberty organization emerged in the city and skirmished over the next ten years with British troops stationed there. The Battle of Long Island , the largest battle of the American Revolutionary War , was fought in August 1776 within modern-day Brooklyn. A British rout of

8505-440: The proper time. Finally, if the mobile is beyond the 35 km cell range of GSM, the transmission will arrive in a neighbouring time slot and be ignored. It is this feature, rather than limitations of power, that limits the range of a GSM cell to 35 km when no special extension techniques are used. By changing the synchronization between the uplink and downlink at the base station, however, this limitation can be overcome. In

8610-523: The region for the Dutch East India Company. In 1614, the area between Cape Cod and Delaware Bay was claimed by the Netherlands and called Nieuw-Nederland (' New Netherland '). The first non–Native American inhabitant of what became New York City was Juan Rodriguez , a merchant from Santo Domingo who arrived in Manhattan during the winter of 1613–14, trapping for pelts and trading with

8715-527: The remaining customers on these older networks onto its GSM network. Alltel completed their shutdown of their D-AMPS and AMPS networks in September 2008. The last carrier in the United States to operate a D-AMPS network was U.S. Cellular , who shut down its D-AMPS network on February 10, 2009. Time-division multiple access Time-division multiple access ( TDMA ) is a channel access method for shared-medium networks . It allows several users to share

8820-688: The rest of the time, the mobile can carry out measurements on the network, detecting surrounding transmitters on different frequencies. This allows safe inter frequency handovers , something which is difficult in CDMA systems, not supported at all in IS-95 and supported through complex system additions in Universal Mobile Telecommunications System (UMTS). This in turn allows for co-existence of microcell layers with macrocell layers. CDMA, by comparison, supports "soft hand-off" which allows

8925-470: The same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This allows multiple stations to share the same transmission medium (e.g. radio frequency channel) while using only a part of its channel capacity . Dynamic TDMA is a TDMA variant that dynamically reserves a variable number of time slots in each frame to variable bit-rate data streams, based on

9030-417: The same area. Capacity was increased over the preceding analog design by dividing each 30 kHz channel pair into three time slots (hence time division ) and digitally compressing the voice data, yielding three times the call capacity in a single cell. A digital system also made calls more secure in the beginning, as analogue scanners could not access digital signals. Calls were encrypted, using CMEA , which

9135-546: The same with its 800 MHz spectrum as the equipment failed. Rogers deactivated its IS-136 network (along with AMPS) on May 31, 2007. AT&T soon followed in February 2008, shutting down both TDMA and AMPS. Alltel , who primarily used CDMA2000 technology but acquired a TDMA network from Western Wireless , shut down its TDMA and AMPS networks in September 2008. US Cellular , which now also primarily uses CDMA2000 technology, shut down its TDMA network in February 2009. IS-54

9240-596: The southern tip of Manhattan to modern-day Wall Street , where a 12-foot (3.7 m) wooden stockade was built in 1653 to protect against Native American and English raids. In 1626, the Dutch colonial Director-General Peter Minuit , as charged by the Dutch West India Company , purchased the island of Manhattan from the Canarsie , a small Lenape band, for "the value of 60 guilders " (about $ 900 in 2018). A frequently told but disproved legend claims that Manhattan

9345-507: The supported range would be mostly impractical anyway. TDMA (Time Division Multiple Access) is a communication method that allocates radio frequency (RF) bandwidth into discrete time slots, allowing multiple users to share the channel in a sequential manner. This approach not only improves spectrum efficiency compared to analog systems but also offers several specific advantages that enhance communication quality and system performance. In dynamic time-division multiple access ( dynamic TDMA ),

9450-545: The surrender permitted Dutch residents to remain in the colony and allowed for religious freedom. In 1667, during negotiations leading to the Treaty of Breda after the Second Anglo-Dutch War , the victorious Dutch decided to keep the nascent plantation colony of what is now Suriname , which they had gained from the English, and in return the English kept New Amsterdam. The settlement was promptly renamed "New York" after

9555-443: The times required. Handsets that are moving will need to constantly adjust their timings to ensure their transmission is received at precisely the right time, because as they move further from the base station, their signal will take longer to arrive. This also means that the major TDMA systems have hard limits on cell sizes in terms of range, though in practice the power levels required to receive and transmit over distances greater than

9660-419: The timing advance to synchronize the transmission. Initial synchronization of a phone requires even more care. Before a mobile transmits there is no way to know the offset required. For this reason, an entire time slot has to be dedicated to mobiles attempting to contact the network; this is known as the random-access channel (RACH) in GSM. The mobile transmits at the beginning of the time slot as received from

9765-520: The traffic demand of each data stream. TDMA is used in the digital 2G cellular systems such as Global System for Mobile Communications (GSM), IS-136 , Personal Digital Cellular (PDC) and iDEN , and in the Digital Enhanced Cordless Telecommunications (DECT) standard for portable phones . TDMA was first used in satellite communication systems by Western Union in its Westar 3 communications satellite in 1979. It

9870-578: The world by pinnacle height, with its spire reaching a symbolic 1,776 feet (541.3 m), a reference to the year of U.S. independence . The Occupy Wall Street protests in Zuccotti Park in the Financial District of Lower Manhattan began on September 17, 2011, receiving global attention and popularizing the Occupy movement against social and economic inequality worldwide. New York City

9975-483: The world's two largest stock exchanges by market capitalization of their listed companies: the New York Stock Exchange and Nasdaq . New York City is an established safe haven for global investors. As of 2023 , New York City is the most expensive city in the world for expatriates and has by a wide margin the highest U.S. city residential rents; and Fifth Avenue is the most expensive shopping street in

10080-521: The world. New York City traces its origins to Fort Amsterdam and a trading post founded on Manhattan Island by Dutch colonists around 1624. The settlement was named New Amsterdam in 1626 and was chartered as a city in 1653. The city came under English control in 1664 and was temporarily renamed New York after King Charles II granted the lands to his brother, the Duke of York , before being permanently renamed New York in November 1674. New York City

10185-402: The world. New York City is home by a significant margin to the highest number of billionaires , individuals of ultra-high net worth (greater than US$ 30 million), and millionaires of any city in the world. In 1664, New York was named in honor of the Duke of York (later King James II of England ). James's elder brother, King Charles II , appointed the Duke as proprietor of

10290-405: Was backward compatible with analogue cellular and indeed co-existed on the same radio channels as AMPS. No analogue customers were left behind; they simply could not access IS-54's new features. IS-54 also supported authentication , a help in preventing fraud. IS-54 employs the same 30 kHz channel spacing and frequency bands (824-849 and 869-894 MHz) as AMPS. Capacity was increased over

10395-552: Was heavily affected by Hurricane Sandy in late October 2012. Sandy's impacts included flooding that led to the days-long shutdown of the subway system and flooding of all East River subway tunnels and of all road tunnels entering Manhattan except the Lincoln Tunnel . The New York Stock Exchange closed for two days due to weather for the first time since the Great Blizzard of 1888 . At least 43 people died in New York City as

10500-525: Was a haven for Loyalist refugees and escaped slaves who joined the British lines for freedom promised by the Crown , with as many as 10,000 escaped slaves crowded into the city during the British occupation, the largest such community on the continent. When the British forces evacuated New York at the close of the war in 1783, they transported thousands of freedmen for resettlement in Nova Scotia , England, and

10605-525: Was a prime destination in the early 20th century for Blacks during the Great Migration from the American South, and by 1916, New York City had the largest urban African diaspora in North America. The Harlem Renaissance of literary and cultural life flourished during the era of Prohibition . The larger economic boom generated construction of skyscrapers competing in height. New York City became

10710-455: Was adopted by the TIA in 1992. TDMA subdivides each of the 30 kHz AMPS channels into three full-rate TDMA channels, each of which is capable of supporting a single voice call. Later, each of these full-rate channels was further sub-divided into two half-rate channels, each of which, with the necessary coding and compression, could also support a voice call. Thus, TDMA could provide three to six times

10815-601: Was later found to be weak. IS-136 added a number of features to the original IS-54 specification, including text messaging , circuit switched data (CSD), and an improved compression protocol. SMS and CSD were both available as part of the GSM protocol, and IS-136 implemented them in a nearly identical fashion. Former large IS-136 networks, including AT&T in the United States, and Rogers Wireless in Canada, have upgraded their existing IS-136 networks to GSM/GPRS. Rogers Wireless removed all 1900 MHz IS-136 in 2003, and has done

10920-415: Was purchased for $ 24 worth of glass beads. Following the purchase, New Amsterdam grew slowly. To attract settlers, the Dutch instituted the patroon system in 1628, whereby wealthy Dutchmen ( patroons , or patrons) who brought 50 colonists to New Netherland would be awarded land, local political autonomy, and rights to participate in the lucrative fur trade. This program had little success. Since 1621,

11025-417: Was the U.S. capital from 1785 until 1790. The modern city was formed by the 1898 consolidation of its five boroughs : Manhattan , Brooklyn , Queens , the Bronx , and Staten Island . Anchored by Wall Street in the Financial District, Manhattan , New York City has been called both the world's premier financial and fintech center and the most economically powerful city in the world. As of 2022 ,

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