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- Diversity_scheme abstract "In telecommunications, a diversity scheme refers to a method for improving the reliability of a message signal by using two or more communication channels with different characteristics. Diversity is mainly used in radio communication and is a common technique for combatting fading and co-channel interference and avoiding error bursts. It is based on the fact that individual channels experience different levels of fading and interference. Multiple versions of the same signal may be transmitted and/or received and combined in the receiver. Alternatively, a redundant forward error correction code may be added and different parts of the message transmitted over different channels. Diversity techniques may exploit the multipath propagation, resulting in a diversity gain, often measured in decibels.The following classes of diversity schemes can be identified: Time diversity: Multiple versions of the same signal are transmitted at different time instants. Alternatively, a redundant forward error correction code is added and the message is spread in time by means of bit-interleaving before it is transmitted. Thus, error bursts are avoided, which simplifies the error correction. Frequency diversity: The signal is transmitted using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading. Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels, and one protection channel for automatic use by any faded channel. Later examples include: OFDM modulation in combination with subcarrier interleaving and forward error correction Spread spectrum, for example frequency hopping or DS-CDMA. Space diversity: The signal is transmitted over several different propagation paths. In the case of wired transmission, this can be achieved by transmitting via multiple wires. In the case of wireless transmission, it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) and/or multiple receiving antennas (reception diversity). In the latter case, a diversity combining technique is applied before further signal processing takes place. If the antennas are far apart, for example at different cellular base station sites or WLAN access points, this is called macrodiversity or site diversity. If the antennas are at a distance in the order of one wavelength, this is called microdiversity. A special case is phased antenna arrays, which also can be used for beamforming, MIMO channels and space–time coding (STC). Polarization diversity: Multiple versions of a signal are transmitted and received via antennas with different polarization. A diversity combining technique is applied on the receiver side. Multiuser diversity: Multiuser diversity is obtained by opportunistic user scheduling at either the transmitter or the receiver. Opportunistic user scheduling is as follows: at any given time, the transmitter selects the best user among candidate receivers according to the qualities of each channel between the transmitter and each receiver. A receiver must feed back the channel quality information to the transmitter using limited levels of resolution, in order for the transmitter to implement Multiuser diversity. Cooperative diversity: Achieves antenna diversity gain by using the cooperation of distributed antennas belonging to each node.".
- Diversity_scheme thumbnail Space_diversity.gif?width=300.
- Diversity_scheme wikiPageExternalLink diversity.php.
- Diversity_scheme wikiPageExternalLink ~enktwong.
- Diversity_scheme wikiPageExternalLink WongKT_APM0205.pdf.
- Diversity_scheme wikiPageExternalLink DiversityDD1.html.
- Diversity_scheme wikiPageExternalLink articles-1.
- Diversity_scheme wikiPageID "7397903".
- Diversity_scheme wikiPageLength "5184".
- Diversity_scheme wikiPageOutDegree "54".
- Diversity_scheme wikiPageRevisionID "647667720".
- Diversity_scheme wikiPageWikiLink Antenna_array.
- Diversity_scheme wikiPageWikiLink Antenna_diversity.
- Diversity_scheme wikiPageWikiLink Aperture_synthesis.
- Diversity_scheme wikiPageWikiLink Beamforming.
- Diversity_scheme wikiPageWikiLink Burst_error.
- Diversity_scheme wikiPageWikiLink Category:Antennas_(radio).
- Diversity_scheme wikiPageWikiLink Category:Radio_resource_management.
- Diversity_scheme wikiPageWikiLink Channel_(communications).
- Diversity_scheme wikiPageWikiLink Channel_access_method.
- Diversity_scheme wikiPageWikiLink Co-channel_interference.
- Diversity_scheme wikiPageWikiLink Cooperative_diversity.
- Diversity_scheme wikiPageWikiLink Cyclic_delay_diversity.
- Diversity_scheme wikiPageWikiLink Decibel.
- Diversity_scheme wikiPageWikiLink Direct-sequence_spread_spectrum.
- Diversity_scheme wikiPageWikiLink Diversity_combining.
- Diversity_scheme wikiPageWikiLink Diversity_gain.
- Diversity_scheme wikiPageWikiLink Fading.
- Diversity_scheme wikiPageWikiLink File:Space_diversity.gif.
- Diversity_scheme wikiPageWikiLink Forward_error_correction.
- Diversity_scheme wikiPageWikiLink Frequency-hopping_spread_spectrum.
- Diversity_scheme wikiPageWikiLink Frequency_diversity.
- Diversity_scheme wikiPageWikiLink Fresnel_zone.
- Diversity_scheme wikiPageWikiLink MIMO.
- Diversity_scheme wikiPageWikiLink Macrodiversity.
- Diversity_scheme wikiPageWikiLink Microdiversity.
- Diversity_scheme wikiPageWikiLink Microwave_transmission.
- Diversity_scheme wikiPageWikiLink Multipath_propagation.
- Diversity_scheme wikiPageWikiLink Multiuser_diversity.
- Diversity_scheme wikiPageWikiLink Orthogonal_frequency-division_multiplexing.
- Diversity_scheme wikiPageWikiLink Polarization_(waves).
- Diversity_scheme wikiPageWikiLink Radio.
- Diversity_scheme wikiPageWikiLink Site_diversity.
- Diversity_scheme wikiPageWikiLink Space–time_code.
- Diversity_scheme wikiPageWikiLink Spread_spectrum.
- Diversity_scheme wikiPageWikiLink Telecommunication.
- Diversity_scheme wikiPageWikiLink Time_diversity.
- Diversity_scheme wikiPageWikiLink Transmit_diversity.
- Diversity_scheme wikiPageWikiLink Tropospheric_scatter.
- Diversity_scheme wikiPageWikiLink Wavelength.
- Diversity_scheme wikiPageWikiLink Wideband.
- Diversity_scheme wikiPageWikiLinkText "Diversity scheme".
- Diversity_scheme wikiPageWikiLinkText "diversity reception".
- Diversity_scheme wikiPageWikiLinkText "diversity scheme".
- Diversity_scheme wikiPageWikiLinkText "diversity techniques".
- Diversity_scheme wikiPageWikiLinkText "diversity".
- Diversity_scheme wikiPageWikiLinkText "frequency diversity".
- Diversity_scheme wikiPageWikiLinkText "physically diverse".
- Diversity_scheme subject Category:Antennas_(radio).
- Diversity_scheme subject Category:Radio_resource_management.
- Diversity_scheme type Protocol.
- Diversity_scheme comment "In telecommunications, a diversity scheme refers to a method for improving the reliability of a message signal by using two or more communication channels with different characteristics. Diversity is mainly used in radio communication and is a common technique for combatting fading and co-channel interference and avoiding error bursts. It is based on the fact that individual channels experience different levels of fading and interference.".
- Diversity_scheme label "Diversity scheme".
- Diversity_scheme sameAs Q1230593.
- Diversity_scheme sameAs Diversity-Technik.
- Diversity_scheme sameAs Διαφορική_λήψη.
- Diversity_scheme sameAs روش_دایورسیتی.
- Diversity_scheme sameAs ダイバーシティ.
- Diversity_scheme sameAs Diversity_(telefonie).
- Diversity_scheme sameAs m.0260gpv.
- Diversity_scheme sameAs வலைவாசல்:தமிழ்க்கணிமை.
- Diversity_scheme sameAs Phân_tập.
- Diversity_scheme sameAs Q1230593.
- Diversity_scheme sameAs 分集.
- Diversity_scheme wasDerivedFrom Diversity_scheme?oldid=647667720.
- Diversity_scheme depiction Space_diversity.gif.
- Diversity_scheme isPrimaryTopicOf Diversity_scheme.