{"id":1397,"date":"2012-01-10T09:59:10","date_gmt":"2012-01-10T09:59:10","guid":{"rendered":"http:\/\/www.raymaps.com\/?p=1397"},"modified":"2012-02-02T05:20:14","modified_gmt":"2012-02-02T05:20:14","slug":"tapped-delay-line","status":"publish","type":"post","link":"https:\/\/www.raymaps.com\/index.php\/tapped-delay-line\/","title":{"rendered":"Implementing a Non-Uniformly Spaced Tapped Delay Line Channel Model"},"content":{"rendered":"<p>Question:<br \/>\nSince you are good on fundamentals I would like to ask you a question that puzzles me. LTE channels models are defined at irregular time intervals as shown in <a href=\"http:\/\/www.steepestascent.com\/content\/mediaassets\/html\/LTE\/Help\/PropagationConditions.html\">[1]<\/a>.<\/p>\n<p>The EPA, EVA and ETU channel taps can best be described as being sampled at multiples of 10 nsec. However, LTE signal is sampled at multiples of 3.84 MHz (Ts=260.416667 nsec). So how does one perform convolution operation.<\/p>\n<p>Answer:<br \/>\nEmpirical multipath channel is usually characterized as a \u03c4-spaced tapped delay line (TDL), whose power delay profile (PDP) is either uniformly spaced, or more frequently, spaced with arbitrary time delay(s). Converting a \u03c4-spaced empirical model to a more tractable T-spaced (sampling time-spaced) statistical model will greatly facilitate the link-level simulation and performance evaluation of the broadband digital wireless system. The practical approaches to accomplish this task could be either approximation or interpolation,<\/p>\n<p>1. Approximation<br \/>\na. Ceil or Floor a \u03c4-spaced tap to the neighbouring sampling time.<br \/>\nb. Split the energy of a \u03c4-spaced tap to the adjacent sampling times.<br \/>\n2. Interpolation<br \/>\nAn Ideal Bandlimited (sinc) Interpolator can fulfil the goal.<\/p>\n<p>It should be noted that although T-spaced statistical model is simpler for analysis, \u03c4-spaced empirical model represents the channel more accurately.<\/p>\n<p>[1] http:\/\/www.steepestascent.com\/content\/mediaassets\/html\/LTE\/Help\/PropagationConditions.html<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Question: Since you are good on fundamentals I would like to ask you a question that puzzles me. LTE channels models are defined at irregular time intervals as shown in [1]. The EPA, EVA and ETU channel taps can best be described as being sampled at multiples of 10 nsec. However, LTE signal is sampled at multiples of 3.84 MHz (Ts=260.416667 nsec). So how does one perform convolution operation. Answer: Empirical multipath channel is usually characterized as a \u03c4-spaced tapped delay line (TDL), whose power delay profile (PDP) is either uniformly spaced, or more frequently, spaced with arbitrary time delay(s). [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8,18],"tags":[47,56,114,57],"class_list":["post-1397","post","type-post","status-publish","format-standard","hentry","category-chanmod","category-lte","tag-4g","tag-channel","tag-lte","tag-multipath"],"_links":{"self":[{"href":"https:\/\/www.raymaps.com\/index.php\/wp-json\/wp\/v2\/posts\/1397","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.raymaps.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.raymaps.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.raymaps.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.raymaps.com\/index.php\/wp-json\/wp\/v2\/comments?post=1397"}],"version-history":[{"count":3,"href":"https:\/\/www.raymaps.com\/index.php\/wp-json\/wp\/v2\/posts\/1397\/revisions"}],"predecessor-version":[{"id":1461,"href":"https:\/\/www.raymaps.com\/index.php\/wp-json\/wp\/v2\/posts\/1397\/revisions\/1461"}],"wp:attachment":[{"href":"https:\/\/www.raymaps.com\/index.php\/wp-json\/wp\/v2\/media?parent=1397"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.raymaps.com\/index.php\/wp-json\/wp\/v2\/categories?post=1397"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.raymaps.com\/index.php\/wp-json\/wp\/v2\/tags?post=1397"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}