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Topic: Time division duplex

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	Duplex (telecommunications) - Wikipedia, the free encyclopedia
		In point to multipoint networks such as cellular networks, both TDD and FDD are used in communication between the base station and the mobile transmitter.
		Time division duplex has a strong advantage in the case where the asymmetry of the uplink and downlink data speed is variable.
		In this case TDD tends to waste bandwidth during switchover from transmit to receive, has greater inherent latency, and may require more complex, more power-hungry circuitry.
	www.wikipedia.org /wiki/Half-duplex (290 words)

	United States Patent: 5,959,982
		A TDD timing device (TDD), as described with reference to the background section, is a controlling device used to time and synchronize periods of transmission and reception between the base station and an individual CPE to optimize communication at a defined physical separation.
		The time period of the offset between the beginning of base transmit and remote receive is a function primarily of the distance of separation between the base and the remote, and increases with further separation.
		The TDD for the exemplary CPE in FIG.
	www.thistle.org /Patent/nph-Parser.html (5654 words)

	Duplex - Wikipedia, the free encyclopedia
		A duplex locomotive is a type of steam locomotive.
		A duplex lamp is a type of oil lamp invented by Joseph Hinks.
		A Duplex (building) is the U.S. name for a type of housing.
	www.wikipedia.org /wiki/Duplex (118 words)

	Time-Division Duplex CDMA Communications
		Guard times of 50 µs (equivalent to a round-trip of 15 km) are placed between the forward and reverse link frames, resulting in a 3.3 percent reduction in data transmission efficiency.
		In TDD systems we can utilize the fact that for a period of time the channel impulse response is the same for the forward and reverse links.
		While TDD facilitates forward link diversity reception at the mobile unit by transmission antenna preselection at the base station, diversity reception in FDD is only possible if multiple antennas are used, while it is necessary to keep the size and cost down.
	www.comsoc.org /pci/private/1997/apr/Esmailzadeh1.html (4148 words)

	Data transmission over a time division duplex channel - Patent 5117423
		Each frame is divided into 24 time slots (or physical channels) of which the first twelve F1 to F12 are allocated for transmission in a forward direction, that is from a primary station to a secondary station, and the second twelve R1 to R12 are allocated for transmission in the reverse direction.
		The reversing of the under-utilised time slots (or physical channels) can be done dynamically in response to monitoring the duplex voice channels and detecting either the absence of signals or the presence of excessive padding and the system controller and/or secondary station deciding to reverse the particular time slots (or physical channels).
		A first possible option is to permit the use of the released time slot(s) (or physical channel(s)) for unidirectional transmission in said one direction so that the pair of time slots (or physical channels) of the or each assigned duplex voice channel are used for transmission of data packets.
	www.freepatentsonline.com /5117423.html (2969 words)

	Time division duplex communications repeater - US Patent 5726980 (Site not responding. Last check: 2007-10-07)
		wherein the signals are time division duplex signals which flow upstream and downstream along the line in alternate time periods, and wherein in the alternate periods the tapped signals are converted from a first to a second carrier frequency and from the second to the first carrier frequency.
		wherein the signals are time division duplex signals which in alternate time periods flow upstream and downstream along the line and in the alternate time periods the converting means converts the tapped signals from a first to a second carrier frequency and from the second to the first carrier frequency.
		Furthermore, it is now proposed to use a time division duplex (TDD) technique to deliver telecoms signals over a transmission line, with transmission to a subscriber and reception from a subscriber over one of a number of single frequency bearer channels.
	www.patentstorm.us /patents/5726980.html (2881 words)

	Duplex
		Duplex is the having of two principal elements or parts.
		A duplex home is a type of housing.
		A Duplex Lamp is a type of oil lamp.
	www.brainyencyclopedia.com /encyclopedia/d/du/duplex.html (352 words)

	Duplex: Definition and Links by Encyclopedian.com - All about Duplex
		In communications, duplex means "two-way" when referring to communications channels.
		Time division duplex (TDD) is the application of Time division multiple access to separate outward and return signals
		Frequency division duplex (FDD) is the application of Frequency division multiple access to separate outward and return signals
	www.encyclopedian.com /ti/Time-division-duplex.html (149 words)

	Smart Base Stations for "Dumb" Time-Division Duplex Terminals
		This scenario is well matched to time-division duplex (TDD) operation, where the uplink and downlink of a duplex channel transmit alternately, on the same frequency, with their respective transmissions separated by the propagation delay.
		Hence, TDD permits most of the functions of matching the mobile receivers to the instantaneously prevailing propagation conditions to be handled instead by preprocessing the signals transmitted from the base station.
		Indeed, when, as is likely, TDD is associated with TDM, a single time-shared equalizer and diversity combiner at the base station, reset by the initial training signal for each pair of duplex time slots, can serve the up- and downlinks of all the mobiles within the cell.
	www.comsoc.org /ci/private/1999/feb/Benjamin.html (5540 words)

	Simultaneous ringing control in the time division duplex telecommunications system - Patent 5103448
		Because portable units will be sleeping most of the time, and wake up in their own time (they are not synchronised), it is not predictable when a handset detects its own poll and starts ringing.
		Since the burst timing of the handset 11 is slaved to the timing of the base station 3, except during multiplex 3 transmissions, the timing information received by the system controller 99 from the S channel controller 101 is not used to control the timing of the operations of the programmable multiplexer 85.
		However the programmable demultiplexer 95 is controlled in accordance with the received burst timing, both to enable correct decoding of multiplex 3 transmissions from a handset 11 and to compensate for the effect of RF transmission delays on transmissions from the handset 11.
	www.freepatentsonline.com /5103448.html (9236 words)

	Combined closed loop/open loop power control in a time division duplex communication system - US Patent 6728292 (Site not responding. Last check: 2007-10-07)
		A transmission power level for the second communication in a second time slot form the user equipment is set based on in part the pathloss estimate weighted by a quality factor adjusted by the power command.
		Typically, in a TDD system, the channels used for estimating path loss are referred to as reference channels, although other channels may be used.
		The baseband signal is processed, such as by a channel estimation device 100 and a data estimation device 102, in the time slots and with the appropriate codes assigned to the communication burst of the receiving station 50.
	www.patentstorm.us /patents/6728292.html (4111 words)

	FT.com - Special Reports / FT Telecoms November 2000 (Site not responding. Last check: 2007-10-07)
		Such is the case with Time Division Duplex (TDD), a multiplexing technology that made its first tentative appearance in early digital standards for fixed networks.
		In the UK, the recent allocation of 28GHz broadband wireless licences and the inclusion of 5GHz of 'bonus' TDD spectrum in four of the five British third-generation FDD licences (the 'unpaired' spectrum component) is already generating strong interest from operators such as BT and Energis.
		In the UK, TDD allocation was bundled with 3G FDD spectrum, while in Germany, prices for TDD allocations hovered at around a mere 2-3 per cent of equivalent FDD spectrum.
	specials.ft.com /telecoms/nov00/FT3QJXIYGFC.html (1014 words)

	Time-division multiplex switching system - United States Patent 3,963,870
		Two-way links communication capability between time-division multiplexed subsystems is provided via dual time division address and data busses correlated by a recirculating memory having sections respectively associated with the address busses.
		Addresses on the address busses are recognized by the individual subsystems and further decoded to gate data to and from the busses data according to time slots assigned to terminal devices in the subsystems.
		The present switching system is preferably used to enable two transmitting/receiving devices which do not belong to the same sub-system to be interconnected, and conventional switching means, which form no part of the present invention and are not shown in the drawings, may be used to interconnected two devices in one given sub-system.
	xrint.com /patents/us/3963870 (2917 words)

	UTRA TDD Physical Layer
		Time slots are units of time in UTRA TDD which have a duration of 625us each or 2560 chips at 4.096Mcps.
		Generally, the spreading factor would be chosen such that an integer number of time slots are completely occupied, and another one partiallu used with a different spreading factor.
		This is achieved by using the time division property, so that both uplink and downlink can be transmitted at the same carrier frequency.
	www.tsp.ece.mcgill.ca /Telecom/Docs/UTRA-TDD.html (800 words)

	Andrew and IPWireless Jointly Develop Technology That Enables Sharing of 3G Cell Site Antennas
		This new duplexer allows wireless operators to deploy both UMTS Frequency Division Duplex (FDD) and UMTS Time Division Duplex (TDD) systems using a single antenna, efficiently taking full advantage of their 3G spectrum to deploy new broadband services and offload traffic from their circuit switched networks.
		Now commercially available, the UMTS FDD/TDD duplexer has already been proven in a number of trials across Europe, and will be used by a number of operators including the recently announced UMTS TDD deployment by Sonaecom in Portugal.
		The TDD systems use time division to separate the uplink and downlink instead of using separate frequency bands, allowing the TDD system to have flexible asymmetry and better match typical data traffic patterns.
	www.theautochannel.com /news/2004/02/23/181576.html (635 words)

	Technology Transfer - Analog Time Division Duplex (ATDD)
		Despite its inconvenience, the half duplex mode is used quite commonly in order to minimise the use of radio frequencies which are at a premium.
		Integr ation of half duplex radio links to telephone networks creates problems when the direction of information flow is controlled from the presence and absence of speech signal.
		A voice signal with duration of T seconds is compressed into T/2 seconds and a time division duplex (TDD) scheme is then used to alternate the transmission of compressed speech signals from each end.
	www.crc.ca /en/html/crc/home/tech_transfer/10101 (358 words)

	Public Notice: Time Division Duplex (TDD) Technology: Applications, Benefits, and Opportunities (Site not responding. Last check: 2007-10-07)
		Therefore, efficient use of systems resources may suggest utilizing a duplexed approach that supports the asymmetric nature of this form of traffic, such as TDD.
		At the tutorial, representatives of the TDD Coalition will provide a comparative overview of duplexing schemes including both frequency division and time division duplexing.
		The current worldwide markets and applications for TDD technology in both mobile and fixed wireless areas will then be discussed.
	www.fcc.gov /Bureaus/Engineering_Technology/Public_Notices/2001/da012754.html (350 words)

	TDD - Time Division Duplex, Training, UMTS
		The use of TDD (Time Division Duplex) across the UMTS air interface to offer low range asymmetric data flows appear an attractive option to operators who are planning to offer 3G data hotspots to subscribers.
		This module explores UMTS TDD operation in detail and discusses the frame formats and procedures that may be used across the air interface.
		The module also describes the issues surrounding TDD operation such as cell blocking and power control as well as the advantages that can be leveraged from such a system.
	www.mpirical.com /TTD.html (106 words)

	Business Wire: Wavtrace Awarded Patent for Invention of Point ... @ HighBeam Research (Site not responding. Last check: 2007-10-07)
		Robert Foster, Wavtrace's founder and chief technology officer, filed for a series of patents related to adaptive TDD and other aspects of third generation point to multipoint systems of which this patent is the first to be awarded.
		Adaptive TDD is the method of establishing a bi-directional communications link using a single channel, whereby any part of the channel up to its full capacity can be used in either the upstream or downstream direction in response to demand.
		The adaptability of TDD, when combined with other dynamically adjustable system parameters, such as variable information densities, link distances, and the sharing of bandwidth among remote units, allows for an overall system design of unprecedented efficiency, providing 20 to 50% greater throughput than systems using older FDD technology (depending on level of asymmetry).
	highbeam.com /library/doc0.asp?DOCID=1G1:59581350&... (682 words)

	Duplex : Time division duplex (Site not responding. Last check: 2007-10-07)
		terms defined : Duplex : Time division duplex
		And as it had got to the ears of fool.html">fool, but a crazy man, to represent us abroad, sundry grave senators curious itching to peep into them.
		And as the president lost no time reader's impatience has never been doubted, I have purloined one, honor.html">honor that it is a precious sample of the flock, and reads as October 14th, 18-.
	www.termsdefined.net /ti/time-division-duplex.html (299 words)

	SurfWax: News, Reviews and Articles On Time Division
		MONMOUTH-Big time Division I campuses usually are full of excitement when their college team is having a successful season.
		Support for both time division duplexing (TDD) and frequency division duplexing (FDD) was incorporated -- providing for both half duplex and full duplex data transmission in cases where FDD is used.
		Those bulky PBX's (phone switches) and time division multiplexed (TDM) systems cost a bundle and won't be dispensed with until their useful life is over.
	telecom.surfwax.com /files/Time_Division.html (4679 words)

	Siemens AG - Coming Soon: Wireless Video Conferencing
		TDD is a radio technology that provides wireless data transfers of up to 2 Mbps over emerging 3G UMTS (Third Generation Universal Mobile Telecommunications System) networks.
		Siemens' UMTS solution is based on two multiplexing modes: TDD and FDD (Frequency Division Duplex).
		Siemens is currently running projects on FDD and TDD in China, Europe and Japan.
	www.siemens.com /page/1,3771,246811-1-999_0_0-0,00.html (177 words)

	TDD
		TDD can stand for several things: telecommunications device for the deaf[?] time division duplex test driven development[?] The airport code for Trinidad, BoliviaThis is a disambiguation page; that is, one that just points to other pages that might otherwise have the same name.
		I'll be a corpse this time next week was already in a weakened condition.
		Here, this is the shanty; at least it's where he cottage, revealing a family group within.
	www.termsdefined.net /td/tdd.html (311 words)

	Interference Considerations for the Time Division Duplex Mode of the UMTS Terrestrial Radio Access (Site not responding. Last check: 2007-10-07)
		However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
		The air interface of the UMTS Terrestrial Radio Access (UTRA) covers both a frequency division duplex (FDD) part for the paired bands and a time division duplex (TDD) part for the unpaired bands of the UMTS spectrum.
		Synchronization and coordination requirements of UTRA TDD are evaluated based on the results.
	www.comsoc.org /sac/private/2000/aug/1386_18sac08-holma.html (338 words)

	PULSAR Wireless Networks - Eliminate self-interference, increase network capacity ten-fold.
		With point to multipoint and linear network topologies, the fixed TDD scheme becomes somewhat more complex as the two phases may be split and used by multiple devices.
		The essential aspect however, is that with a fixed TDD scheme across all topologies, co-located radios are never in the situation depicted in figure 1.
		If at any time the current master device is turned off, the other devices perform a new negotiation and choose a new master.
	www.afar.net /solution/pulsar.htm (1456 words)

	3G Operators Will Find It Hard To Ignore TD-SCDMA - 12/3/2001 - Wireless Week - CA184229 (Site not responding. Last check: 2007-10-07)
		This happened at a time when we were looking at the mainland Chinese market as a major focus.
		At the same time, the lack of these features makes WLANs very cheap, easy to deploy, extremely fast and available, which is especially interesting for enterprises.
		In Germany, we have five operators that also bought TDD licenses based on the fact that they want to use this frequency as well for a pretty low investment, compared to the FDD licenses.
	www.wirelessweek.com /article/CA184229.html?spacedesc=News&stt=001 (1525 words)

	Citations: A Review of Time Division Duplex CDMA Techniques - Povey, Nakagawa (SMEALSearch) - ... (Site not responding. Last check: 2007-10-07)
		Thus, D TDD is robust to asymmetric and time varying multimedia traffic by adapting its boundary to dynamic traffic load level
		It has been established that the throughput of TDD systems is decreased, as the cell coverage is increased.
		This is mainly due to the increase in the guard time.
	smealsearch2.psu.edu /context/38180/0 (164 words)

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