Delay Spread
🛑 ALL INFORMATION CLICK HERE 👈🏻👈🏻👈🏻
Delay Spread
In system evaluations, we typically prefer to address a class of channels
with properties that are likely to be encountered, rather than one specific
impulse response. Therefor we define the (local-mean) average power which is
received with an excess delay that falls within the interval ( T , T
+ dt ). Such characterization for all T gives the "delay profile"
of the channel.
The delay profile determines the frequency dispersion, that is, the extent
to which the channel fading at two different frequencies f 1
and f 2 is correlated .
MP2 audio : Measured channel
data in Edinburgh.
Source: Research group of Prof. Peter
Grant , U. of Edinbourough. See also: discussion of channel
modeling to study CDMA
array processing . Playlist
leading you through the topic of array processing and adaptive antennas
for CDMA. It includes a discussion of the channel model.
In indoor and micro-cellular channels, the delay spread is usually smaller, and rarely exceed a few hundred nanoseconds. Seidel and Rappaport reported delay spreads in four European cities of less than 8 microsec in macro-cellular channels, less than 2 microsec in micro-cellular channels, and between 50 and 300 ns in pico-cellular channels.
Figure: Typical delay profile: Exponential
Figure: Typical indoor delay profile:
In an indoor environment, early reflections
often arrive with almost identical power. This gives a fairly flat profile up to some
point, and a tail of weaker reflections with larger excess delay.
Figure: Typical "bad urban" delay profile
Besides the normal reflections from nearby obstacles (which cause reflection with a short excess delay),
remote high-rise buildings cause strong reflections with large excess delay.
The combined effects often result in multiple clusters of reflections.
From the delay profile, one can compute the correlation of the fading
at different carrier frequencies.
Figure Auto-Covariance of the received amplitude of
two carriers transmitted with certain frequency offset.
The above expressions only represent the behavior of the profile curve.
A correction factor is needed to ensure that the integral over all t equals unity, or to represent the total local-mean power.
Often propagation parameters are measured in frequency domain. Klaus Witrisal
discusses how the delay spread can be estimated
directly from a frequency transfer function .
Figure: Example of impulse response and frequency transfer function
of a multipath channel.
Figure: Measured Delay profile in a German urban environment at 1800 MHz
Delay Spread = 1.2 m sec; coherence BW = 1.3 MHz
Source: Research group of Prof. Paul Walter Baier, U. of Kaiserslautern, Germany.
See also: corresponding scatter plot .
FIGURE: R.M.S. Delay Spread vs. propagation distance in the
U.C. Berkeley, Cory Hall Building.
Source: John Davis and Jean-Paul Linnartz
Figure: Illustration of reflections of various kinds.
Source: Peter Grant, U. of Edinbourough.
exp(- t /1 m s)
0.5 exp(5- t /1 m s)
for 0 < t < 5 m s
for 5 < t < 10 m s
exp(-3.5 t /1 m s)
0.1 exp(15- t /1 m s)
for 0 < t < 2 m s
for 15 < t < 20 m s
Adaptive channel equalization
Channel estimation training sequence
Use the handset only in small cells with small delay spreads
Diversity and channel selection can help a little bit (pick a channel where late reflections are in a fade)
Rake receiver separately recovers signals over paths with excessive delays.
CDMA array processing can further improve
performance, because it also exploits angle spreads .
OFDM multi-carrier modulation: The radio
channel is split into many narrowband (ISI-free) subchannels
Delay spread — Wikipedia Republished // WIKI 2
Delay Spread
delay spread - это... Что такое delay spread ?
Delay Spread - YouTube
Delay Spread | Doppler Spread
Все языки Абхазский Адыгейский Африкаанс Айнский язык Акан Алтайский Арагонский Арабский Астурийский Аймара Азербайджанский Башкирский Багобо Белорусский Болгарский Тибетский Бурятский Каталанский Чеченский Шорский Чероки Шайенского Кри Чешский Крымскотатарский Церковнославянский (Старославянский) Чувашский Валлийский Датский Немецкий Долганский Греческий Английский Эсперанто Испанский Эстонский Баскский Эвенкийский Персидский Финский Фарерский Французский Ирландский Гэльский Гуарани Клингонский Эльзасский Иврит Хинди Хорватский Верхнелужицкий Гаитянский Венгерский Армянский Индонезийский Инупиак Ингушский Исландский Итальянский Японский Грузинский Карачаевский Черкесский Казахский Кхмерский Корейский Кумыкский Курдский Коми Киргизский Латинский Люксембургский Сефардский Лингала Литовский Латышский Маньчжурский Микенский Мокшанский Маори Марийский Македонский Коми Монгольский Малайский Майя Эрзянский Нидерландский Норвежский Науатль Орокский Ногайский Осетинский Османский Пенджабский Пали Польский Папьяменто Древнерусский язык Португальский Кечуа Квенья Румынский, Молдавский Арумынский Русский Санскрит Северносаамский Якутский Словацкий Словенский Албанский Сербский Шведский Суахили Шумерский Силезский Тофаларский Таджикский Тайский Туркменский Тагальский Турецкий Татарский Тувинский Тви Удмурдский Уйгурский Украинский Урду Урумский Узбекский Вьетнамский Вепсский Варайский Юпийский Идиш Йоруба Китайский
Все языки Абхазский Адыгейский Африкаанс Айнский язык Алтайский Арабский Аварский Аймара Азербайджанский Башкирский Белорусский Болгарский Каталанский Чеченский Чаморро Шорский Чероки Чешский Крымскотатарский Церковнославянский (Старославянский) Чувашский Датский Немецкий Греческий Английский Эсперанто Испанский Эстонский Баскский Эвенкийский Персидский Финский Фарерский Французский Ирландский Галисийский Клингонский Эльзасский Иврит Хинди Хорватский Гаитянский Венгерский Армянский Индонезийский Ингушский Исландский Итальянский Ижорский Японский Ложбан Грузинский Карачаевский Казахский Кхмерский Корейский Кумыкский Курдский Латинский Лингала Литовский Латышский Мокшанский Маори Марийский Македонский Монгольский Малайский Мальтийский Майя Эрзянский Нидерландский Норвежский Осетинский Пенджабский Пали Польский Папьяменто Древнерусский язык Пушту Португальский Кечуа Квенья Румынский, Молдавский Русский Якутский Словацкий Словенский Албанский Сербский Шведский Суахили Тамильский Таджикский Тайский Туркменский Тагальский Турецкий Татарский Удмурдский Уйгурский Украинский Урду Урумский Узбекский Водский Вьетнамский Вепсский Идиш Йоруба Китайский
Мы разработали для вас новый сервис!
Пользуясь Скидки.Академик.ру , вы поддерживаете Академик.ру!
English - Russian electronics dictionary .
Delay spread — In telecommunications , the delay spread is a measure of the multipath richness of a communications channel . In general , it can be interpreted as the difference between the time of arrival of the earliest significant multipath component ( typically … Wikipedia
Delay Tolerant Networking — ( DTN ) is an approach to computer network architecture that seeks to address the technical issues in heterogeneous networks that may lack continuous network connectivity . Examples of such networks are those operating in mobile or extreme … … Wikipedia
spread — spread1 [ spred ] ( past tense and past participle spread ) verb *** ▸ 1 affect larger area ▸ 2 disease affects many ▸ 3 cover surface with something ▸ 4 divide / reduce something ▸ 5 be present in wide area ▸ 6 give information to many ▸ 7 move … … Usage of the words and phrases in modern English
spread — I UK [ spred ] / US verb Word forms spread : present tense I / you / we / they spread he / she / it spreads present participle spreading past tense spread past participle spread *** 1 ) a ) [ intransitive ] to gradually affect or cover a larger area UN leaders … … English dictionary
Delay - action bomb — A delay action bomb is an aerial bomb designed to explode some time after impact , with the bomb s fuzes set to delay the explosion for times ranging from very brief to several weeks . Short delays were used to allow the bomb to penetrate before … … Wikipedia
Power delay profile — The power delay profile ( PDP ) gives the intensity of a signal received through a multipath channel as a function of time delay . The time delay is the difference in travel time between multipath arrivals . The abscissa is in units of time and the … … Wikipedia
History of delay tolerant networking — The history of delay tolerant networking examines the bulk of the technologies that began the field that is known today as Delay Tolerant Networking . Research began as projects under United States government grants relating to the necessity of … … Wikipedia
Global spread of H5N1 in 2004 — The global spread of ( highly pathogenic ) H5N1 in birds is considered a significant pandemic threat . While prior H5N1 strains have been known , they were significantly different from the current H5N1 strain on a genetic level , making the global … … Wikipedia
Global spread of H5N1 — The global spread of highly pathogenic H5N1 in birds is considered a significant pandemic threat . While other H5N1 strains are known , they are significantly different from a current , highly pathogenic H5N1 strain on a genetic level , making the … … Wikipedia
Cyclic delay diversity — ( CDD ) is a diversity scheme used in OFDM based telecommunication systems , transforming spatial diversity into frequency diversity avoiding intersymbol interference . CDD was introduced in 2001 and can gain frequency diversity at the receiver … … Wikipedia
Digital Radio Mondiale — ( abbreviated DRM ; mondiale being Italian and French for worldwide ) is a set of digital audio broadcasting technologies designed to work over the bands currently used for AM broadcasting , particularly shortwave . DRM can fit more channels than AM … Wikipedia
Public Beach Sex
Mature Cum Sperm
Shaved Mature
Naked Dance
Japanese Sleep Sex Video
