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  • 2021-04-13 12:23
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Advances in Cognitive Radio Networks: A Survey
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内容介绍
<html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta charset="utf-8"> <meta name="generator" content="pdf2htmlEX"> <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"> <link rel="stylesheet" href="https://static.pudn.com/base/css/base.min.css"> <link rel="stylesheet" href="https://static.pudn.com/base/css/fancy.min.css"> <link rel="stylesheet" href="https://static.pudn.com/prod/directory_preview_static/6255e9b6b744eb386feed92b/raw.css"> <script src="https://static.pudn.com/base/js/compatibility.min.js"></script> <script src="https://static.pudn.com/base/js/pdf2htmlEX.min.js"></script> <script> try{ pdf2htmlEX.defaultViewer = new pdf2htmlEX.Viewer({}); }catch(e){} </script> <title></title> </head> <body> <div id="sidebar" style="display: none"> <div id="outline"> </div> </div> <div id="pf1" class="pf w0 h0" data-page-no="1"><div class="pc pc1 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/6255e9b6b744eb386feed92b/bg1.jpg"><div class="t m0 x1 h2 y1 ff1 fs0 fc0 sc0 ls0 ws0">IEEE<span class="_ _0"> </span>JOURNAL<span class="_ _0"> </span>OF<span class="_ _1"> </span>SELECTED<span class="_ _1"> </span>TOPICS<span class="_ _0"> </span>IN<span class="_ _0"> </span>SIGNAL<span class="_ _1"> </span>PROCESSING,<span class="_ _1"> </span>VOL.<span class="_ _1"> </span>5,<span class="_ _0"> </span>NO.<span class="_ _0"> </span>1,<span class="_ _0"> </span>FEBR<span class="_ _2"></span>U<span class="_ _2"></span>AR<span class="_ _3"></span>Y<span class="_ _0"> </span>2011<span class="_ _4"> </span>5</div><div class="t m0 x2 h3 y2 ff1 fs1 fc0 sc0 ls1 ws0">Adv<span class="_ _3"></span>ances<span class="_ _5"> </span>in<span class="_ _5"> </span>Cogniti<span class="_ _3"></span>v<span class="_ _3"></span>e<span class="_ _6"> </span>Radio<span class="_ _5"> </span>Networks:<span class="_ _5"> </span>A<span class="_ _5"> </span>Surv<span class="_ _3"></span>ey</div><div class="t m0 x3 h4 y3 ff1 fs2 fc0 sc0 ls1 ws0">Beibei<span class="_ _7"> </span>W<span class="_ _8"></span>ang<span class="_ _9"> </span>and<span class="_ _a"> </span>K.<span class="_ _7"> </span>J.<span class="_ _b"> </span>Ray<span class="_ _7"> </span>Liu</div><div class="t m0 x4 h5 y4 ff2 fs3 fc0 sc0 ls1 ws0">Abstract&#8212;<span class="ff3">With<span class="_ _b"> </span>the<span class="_ _c"> </span>rapid<span class="_ _b"> </span>deployment<span class="_ _c"> </span>of<span class="_ _c"> </span>new<span class="_ _c"> </span>wireless<span class="_ _b"> </span>devices</span></div><div class="t m0 x1 h6 y5 ff3 fs3 fc0 sc0 ls1 ws0">and<span class="_ _d"> </span>applications,<span class="_ _d"> </span>the<span class="_ _d"> </span>last<span class="_ _d"> </span>decade<span class="_ _d"> </span>has<span class="_ _d"> </span>witnessed<span class="_ _d"> </span>a<span class="_ _d"> </span>gr<span class="_ _3"></span>owing<span class="_ _d"> </span>demand</div><div class="t m0 x1 h6 y6 ff3 fs3 fc0 sc0 ls1 ws0">for<span class="_ _e"> </span>wireless<span class="_ _e"> </span>radio<span class="_ _7"> </span>spectrum.<span class="_ _e"> </span>However<span class="_ _8"></span>,<span class="_ _e"> </span>the<span class="_ _7"> </span>&#64257;xed<span class="_ _7"> </span>spectrum<span class="_ _e"> </span>assign-</div><div class="t m0 x1 h6 y7 ff3 fs3 fc0 sc0 ls1 ws0">ment<span class="_ _d"> </span>policy<span class="_ _e"> </span>becomes<span class="_ _d"> </span>a<span class="_ _d"> </span>bottleneck<span class="_ _e"> </span>f<span class="_ _3"></span>or<span class="_ _e"> </span>more<span class="_ _d"> </span>ef&#64257;cient<span class="_ _d"> </span>spectrum<span class="_ _d"> </span>uti-</div><div class="t m0 x1 h6 y8 ff3 fs3 fc0 sc0 ls1 ws0">lization,<span class="_ _7"> </span>under<span class="_ _7"> </span>which<span class="_ _7"> </span>a<span class="_ _7"> </span>great<span class="_ _7"> </span>portion<span class="_ _7"> </span>of<span class="_ _7"> </span>the<span class="_ _7"> </span>licensed<span class="_ _7"> </span>spectrum<span class="_ _7"> </span>is</div><div class="t m0 x1 h6 y9 ff3 fs3 fc0 sc0 ls1 ws0">sever<span class="_ _3"></span>ely<span class="_ _7"> </span>under-utilized.<span class="_ _7"> </span>The<span class="_ _7"> </span>inef&#64257;cient<span class="_ _7"> </span>usage<span class="_ _7"> </span>of<span class="_ _7"> </span>the<span class="_ _7"> </span>limited<span class="_ _7"> </span>spec-</div><div class="t m0 x1 h6 ya ff3 fs3 fc0 sc0 ls1 ws0">trum<span class="_ _c"> </span>resources<span class="_ _b"> </span>urges<span class="_ _c"> </span>the<span class="_ _f"> </span>spectrum<span class="_ _c"> </span>regulatory<span class="_ _c"> </span>bodies<span class="_ _c"> </span>to<span class="_ _f"> </span>re<span class="_ _3"></span>view</div><div class="t m0 x1 h6 yb ff3 fs3 fc0 sc0 ls1 ws0">their<span class="_ _e"> </span>policy<span class="_ _e"> </span>and<span class="_ _e"> </span>start<span class="_ _7"> </span>to<span class="_ _e"> </span>seek<span class="_ _e"> </span>for<span class="_ _e"> </span>innovativ<span class="_ _3"></span>e<span class="_ _e"> </span>communication<span class="_ _e"> </span>tech-</div><div class="t m0 x1 h6 yc ff3 fs3 fc0 sc0 ls1 ws0">nology<span class="_ _d"> </span>that<span class="_ _d"> </span>can<span class="_ _d"> </span>exploit<span class="_ _d"> </span>the<span class="_ _e"> </span>wir<span class="_ _3"></span>eless<span class="_ _d"> </span>spectrum<span class="_ _e"> </span>in<span class="_ _d"> </span>a<span class="_ _d"> </span>more<span class="_ _d"> </span>intelligent</div><div class="t m0 x1 h6 yd ff3 fs3 fc0 sc0 ls1 ws0">and<span class="_ _d"> </span>&#64258;exible<span class="_ _d"> </span>way.<span class="_ _d"> </span>The<span class="_ _d"> </span>concept<span class="_ _d"> </span>of<span class="_ _0"> </span>cognitive<span class="_ _d"> </span>radio<span class="_ _d"> </span>is<span class="_ _d"> </span>pr<span class="_ _3"></span>oposed<span class="_ _d"> </span>to<span class="_ _d"> </span>ad-</div><div class="t m0 x1 h6 ye ff3 fs3 fc0 sc0 ls1 ws0">dress<span class="_ _0"> </span>the<span class="_ _d"> </span>issue<span class="_ _0"> </span>of<span class="_ _d"> </span>spectrum<span class="_ _0"> </span>ef&#64257;ciency<span class="_ _d"> </span>and<span class="_ _0"> </span>has<span class="_ _d"> </span>been<span class="_ _0"> </span>receiving<span class="_ _0"> </span>an<span class="_ _d"> </span>in-</div><div class="t m0 x1 h6 yf ff3 fs3 fc0 sc0 ls1 ws0">creasing<span class="_ _0"> </span>attention<span class="_ _d"> </span>in<span class="_ _0"> </span>recent<span class="_ _0"> </span>years,<span class="_ _d"> </span>since<span class="_ _0"> </span>it<span class="_ _d"> </span>equips<span class="_ _0"> </span>wireless<span class="_ _0"> </span>users<span class="_ _0"> </span>the</div><div class="t m0 x1 h6 y10 ff3 fs3 fc0 sc0 ls1 ws0">capability<span class="_ _1"> </span>to<span class="_ _1"> </span>optimally<span class="_ _1"> </span>adapt<span class="_ _1"> </span>their<span class="_ _1"> </span>operating<span class="_ _1"> </span>parameters<span class="_ _1"> </span>according</div><div class="t m0 x1 h6 y11 ff3 fs3 fc0 sc0 ls1 ws0">to<span class="_ _d"> </span>the<span class="_ _0"> </span>interactions<span class="_ _d"> </span>with<span class="_ _0"> </span>the<span class="_ _d"> </span>surr<span class="_ _3"></span>ounding<span class="_ _d"> </span>radio<span class="_ _d"> </span>en<span class="_ _3"></span>vironment.<span class="_ _0"> </span>There</div><div class="t m0 x1 h6 y12 ff3 fs3 fc0 sc0 ls1 ws0">hav<span class="_ _3"></span>e<span class="_ _e"> </span>been<span class="_ _d"> </span>many<span class="_ _e"> </span>signi&#64257;cant<span class="_ _d"> </span>developments<span class="_ _d"> </span>in<span class="_ _d"> </span>the<span class="_ _e"> </span>past<span class="_ _d"> </span>few<span class="_ _e"> </span>years<span class="_ _d"> </span>on</div><div class="t m0 x1 h6 y13 ff3 fs3 fc0 sc0 ls1 ws0">cognitive<span class="_ _e"> </span>radios.<span class="_ _7"> </span>This<span class="_ _7"> </span>paper<span class="_ _7"> </span>surveys<span class="_ _7"> </span>recent<span class="_ _7"> </span>advances<span class="_ _e"> </span>in<span class="_ _7"> </span>research</div><div class="t m0 x1 h6 y14 ff3 fs3 fc0 sc0 ls1 ws0">related<span class="_ _7"> </span>to<span class="_ _c"> </span>cognitive<span class="_ _b"> </span>radios.<span class="_ _b"> </span>The<span class="_ _b"> </span>fundamentals<span class="_ _b"> </span>of<span class="_ _b"> </span>cognitive<span class="_ _b"> </span>radio</div><div class="t m0 x1 h6 y15 ff3 fs3 fc0 sc0 ls1 ws0">technology<span class="_ _3"></span>,<span class="_ _0"> </span>architecture<span class="_ _0"> </span>of<span class="_ _0"> </span>a<span class="_ _d"> </span>cognitive<span class="_ _1"> </span>radio<span class="_ _d"> </span>network<span class="_ _1"> </span>and<span class="_ _d"> </span>its<span class="_ _0"> </span>appli-</div><div class="t m0 x1 h6 y16 ff3 fs3 fc0 sc0 ls1 ws0">cations<span class="_ _1"> </span>are<span class="_ _1"> </span>&#64257;rst<span class="_ _1"> </span>intr<span class="_ _2"></span>oduced.<span class="_ _1"> </span>The<span class="_ _1"> </span>existing<span class="_ _1"> </span>works<span class="_ _1"> </span>in<span class="_ _1"> </span>spectrum<span class="_ _1"> </span>sensing</div><div class="t m0 x1 h6 y17 ff3 fs3 fc0 sc0 ls1 ws0">are<span class="_ _1"> </span>re<span class="_ _2"></span>viewed,<span class="_ _0"> </span>and<span class="_ _1"> </span>important<span class="_ _0"> </span>issues<span class="_ _0"> </span>in<span class="_ _0"> </span>dynamic<span class="_ _0"> </span>spectrum<span class="_ _0"> </span>allocation</div><div class="t m0 x1 h6 y18 ff3 fs3 fc0 sc0 ls1 ws0">and<span class="_ _e"> </span>sharing<span class="_ _d"> </span>are<span class="_ _d"> </span>investigated<span class="_ _d"> </span>in<span class="_ _d"> </span>detail.</div><div class="t m0 x4 h5 y19 ff2 fs3 fc0 sc0 ls1 ws0">Index<span class="_ _7"> </span>T<span class="_ _8"></span>erms&#8212;<span class="ff3">Cognitive<span class="_ _b"> </span>radio<span class="_ _7"> </span>(CR),<span class="_ _b"> </span>platf<span class="_ _2"></span>orms<span class="_ _7"> </span>and<span class="_ _b"> </span>standards,</span></div><div class="t m0 x1 h6 y1a ff3 fs3 fc0 sc0 ls1 ws0">radio<span class="_ _c"> </span>spectrum<span class="_ _c"> </span>management,<span class="_ _c"> </span>software<span class="_ _c"> </span>radio,<span class="_ _c"> </span>spectrum<span class="_ _c"> </span>sensing,</div><div class="t m0 x1 h6 y1b ff3 fs3 fc0 sc0 ls1 ws0">wireless<span class="_ _d"> </span>communication.</div><div class="t m0 x5 h7 y1c ff1 fs4 fc0 sc0 ls1 ws0">I.<span class="_ _5"> </span>I<span class="fs5">NTR<span class="_ _3"></span>ODUCTION</span></div><div class="t m0 x1 h8 y1d ff3 fs6 fc0 sc0 ls1 ws0">T</div><div class="t m0 x6 h7 y1e ff1 fs4 fc0 sc0 ls1 ws0">HE<span class="_ _e"> </span>usage<span class="_ _e"> </span>of<span class="_ _e"> </span>radio<span class="_ _e"> </span>spectrum<span class="_ _e"> </span>resources<span class="_ _e"> </span>and<span class="_ _e"> </span>the<span class="_ _7"> </span>regulation</div><div class="t m0 x6 h7 y1f ff1 fs4 fc0 sc0 ls1 ws0">of<span class="_ _d"> </span>radio<span class="_ _e"> </span>emissions<span class="_ _d"> </span>are<span class="_ _e"> </span>coordinated<span class="_ _d"> </span>by<span class="_ _e"> </span>national<span class="_ _d"> </span>regulatory</div><div class="t m0 x1 h7 y20 ff1 fs4 fc0 sc0 ls1 ws0">bodies<span class="_ _c"> </span>like<span class="_ _b"> </span>the<span class="_ _c"> </span>Federal<span class="_ _f"> </span>Communications<span class="_ _b"> </span>Commission<span class="_ _c"> </span>(FCC).</div><div class="t m0 x1 h7 y21 ff1 fs4 fc0 sc0 ls1 ws0">The<span class="_ _7"> </span>FCC<span class="_ _7"> </span>assigns<span class="_ _b"> </span>spectrum<span class="_ _7"> </span>to<span class="_ _7"> </span>licensed<span class="_ _b"> </span>holders,<span class="_ _7"> </span>also<span class="_ _7"> </span>known<span class="_ _7"> </span>as</div><div class="t m0 x1 h7 y22 ff4 fs4 fc0 sc0 ls1 ws0">primary<span class="_ _7"> </span>users<span class="ff1">,<span class="_ _7"> </span>on<span class="_ _b"> </span>a<span class="_ _7"> </span>long-term<span class="_ _7"> </span>basis<span class="_ _7"> </span>for<span class="_ _b"> </span>large<span class="_ _7"> </span>geographical<span class="_ _7"> </span>re-</span></div><div class="t m0 x1 h7 y23 ff1 fs4 fc0 sc0 ls1 ws0">gions.<span class="_ _c"> </span>Howe<span class="_ _3"></span>ver<span class="_ _3"></span>,<span class="_ _f"> </span>a<span class="_ _c"> </span>large<span class="_ _c"> </span>portion<span class="_ _c"> </span>of<span class="_ _f"> </span>the<span class="_ _c"> </span>assigned<span class="_ _f"> </span>spectrum<span class="_ _c"> </span>re-</div><div class="t m0 x1 h7 y24 ff1 fs4 fc0 sc0 ls1 ws0">mains<span class="_ _0"> </span>under<span class="_ _1"> </span>utilized<span class="_ _0"> </span>as<span class="_ _0"> </span>illustrated<span class="_ _0"> </span>in<span class="_ _0"> </span>Fig.<span class="_ _0"> </span>1.<span class="_ _0"> </span>The<span class="_ _0"> </span>inef&#64257;cient<span class="_ _1"> </span>usage</div><div class="t m0 x1 h7 y25 ff1 fs4 fc0 sc0 ls1 ws0">of<span class="_ _9"> </span>the<span class="_ _9"> </span>limited<span class="_ _9"> </span>spectrum<span class="_ _9"> </span>necessitates<span class="_ _9"> </span>the<span class="_ _9"> </span>development<span class="_ _f"> </span>of<span class="_ _9"> </span>dy-</div><div class="t m0 x1 h7 y26 ff1 fs4 fc0 sc0 ls1 ws0">namic<span class="_ _c"> </span>spectrum<span class="_ _c"> </span>access<span class="_ _c"> </span>techniques,<span class="_ _c"> </span>where<span class="_ _f"> </span>users<span class="_ _b"> </span>who<span class="_ _f"> </span>hav<span class="_ _3"></span>e<span class="_ _c"> </span>no</div><div class="t m0 x1 h7 y27 ff1 fs4 fc0 sc0 ls1 ws0">spectrum<span class="_ _e"> </span>licenses,<span class="_ _e"> </span>also<span class="_ _e"> </span>known<span class="_ _e"> </span>as<span class="_ _e"> </span><span class="ff4">secondary<span class="_ _e"> </span>users</span>,<span class="_ _e"> </span>are<span class="_ _e"> </span>allo<span class="_ _3"></span>wed</div><div class="t m0 x1 h7 y28 ff1 fs4 fc0 sc0 ls1 ws0">to<span class="_ _1"> </span>use<span class="_ _0"> </span>the<span class="_ _0"> </span>temporarily<span class="_ _0"> </span>unused<span class="_ _0"> </span>licensed<span class="_ _1"> </span>spectrum.<span class="_ _0"> </span>In<span class="_ _0"> </span>recent<span class="_ _0"> </span>years,</div><div class="t m0 x1 h7 y29 ff1 fs4 fc0 sc0 ls1 ws0">the<span class="_ _d"> </span>FCC<span class="_ _d"> </span>has<span class="_ _0"> </span>been<span class="_ _d"> </span>considering<span class="_ _d"> </span>more<span class="_ _d"> </span>&#64258;e<span class="_ _2"></span>xible<span class="_ _d"> </span>and<span class="_ _0"> </span>comprehensive</div><div class="t m0 x1 h7 y2a ff1 fs4 fc0 sc0 ls1 ws0">uses<span class="_ _e"> </span>of<span class="_ _e"> </span>the<span class="_ _e"> </span>a<span class="_ _3"></span>vailable<span class="_ _e"> </span>spectrum<span class="_ _e"> </span>[1],<span class="_ _e"> </span>through<span class="_ _d"> </span>the<span class="_ _e"> </span>use<span class="_ _e"> </span>of<span class="_ _e"> </span><span class="ff4">cognitive</span></div><div class="t m0 x1 h7 y2b ff4 fs4 fc0 sc0 ls1 ws0">radio<span class="_ _e"> </span><span class="ff1">technology<span class="_ _7"> </span>[2].</span></div><div class="t m0 x7 h7 y2c ff1 fs4 fc0 sc0 ls1 ws0">Cognitiv<span class="_ _3"></span>e<span class="_ _b"> </span>radio<span class="_ _7"> </span>is<span class="_ _b"> </span>the<span class="_ _7"> </span>key<span class="_ _7"> </span>enabling<span class="_ _7"> </span>technology<span class="_ _b"> </span>that<span class="_ _7"> </span>enables</div><div class="t m0 x1 h7 y2d ff1 fs4 fc0 sc0 ls1 ws0">next<span class="_ _c"> </span>generation<span class="_ _c"> </span>communication<span class="_ _f"> </span>networks,<span class="_ _c"> </span>also<span class="_ _f"> </span>known<span class="_ _c"> </span>as<span class="_ _c"> </span>dy-</div><div class="t m0 x8 h9 y2e ff1 fs5 fc0 sc0 ls1 ws0">Manuscript<span class="_ _e"> </span>recei<span class="_ _2"></span>ved<span class="_ _d"> </span>October<span class="_ _e"> </span>30,<span class="_ _e"> </span>2009<span class="_ _d"> </span>accepted<span class="_ _e"> </span>October<span class="_ _e"> </span>24,<span class="_ _e"> </span>2010.<span class="_ _d"> </span>Date<span class="_ _e"> </span>of</div><div class="t m0 x1 h9 y2f ff1 fs5 fc0 sc0 ls1 ws0">publication<span class="_ _d"> </span>Nov<span class="_ _3"></span>ember<span class="_ _d"> </span>18,<span class="_ _d"> </span>2010;<span class="_ _0"> </span>date<span class="_ _d"> </span>of<span class="_ _d"> </span>current<span class="_ _0"> </span>version<span class="_ _d"> </span>January<span class="_ _0"> </span>19,<span class="_ _d"> </span>2011.<span class="_ _d"> </span>The</div><div class="t m0 x1 h9 y30 ff1 fs5 fc0 sc0 ls1 ws0">associate<span class="_ _0"> </span>editor<span class="_ _d"> </span>coordinating<span class="_ _0"> </span>the<span class="_ _d"> </span>re<span class="_ _3"></span>view<span class="_ _0"> </span>of<span class="_ _d"> </span>this<span class="_ _0"> </span>manuscript<span class="_ _0"> </span>and<span class="_ _d"> </span>approving<span class="_ _0"> </span>it<span class="_ _0"> </span>for</div><div class="t m0 x1 h9 y31 ff1 fs5 fc0 sc0 ls1 ws0">publication<span class="_ _d"> </span>was<span class="_ _d"> </span>Dr.<span class="_ _d"> </span>Sastri<span class="_ _d"> </span>Kota.</div><div class="t m0 x8 h9 y32 ff1 fs5 fc0 sc0 ls1 ws0">B.<span class="_ _0"> </span>W<span class="_ _3"></span>ang<span class="_ _1"> </span>is<span class="_ _0"> </span>with<span class="_ _0"> </span>Corporate<span class="_ _0"> </span>Research<span class="_ _1"> </span>and<span class="_ _0"> </span>Development,<span class="_ _1"> </span>Qualcomm,<span class="_ _0"> </span>Inc.,<span class="_ _1"> </span>San</div><div class="t m0 x1 h9 y33 ff1 fs5 fc0 sc0 ls1 ws0">Diego,<span class="_ _0"> </span>CA<span class="_ _d"> </span>92121<span class="_ _d"> </span>USA<span class="_ _d"> </span>(e-mail:<span class="_ _d"> </span>beibeiw@qualcomm.com).</div><div class="t m0 x8 h9 y34 ff1 fs5 fc0 sc0 ls1 ws0">K.<span class="_ _f"> </span>J.<span class="_ _c"> </span>R.<span class="_ _f"> </span>Liu<span class="_ _f"> </span>is<span class="_ _f"> </span>with<span class="_ _f"> </span>the<span class="_ _f"> </span>Department<span class="_ _f"> </span>of<span class="_ _c"> </span>Electrical<span class="_ _f"> </span>and<span class="_ _f"> </span>Computer<span class="_ _f"> </span>Engi-</div><div class="t m0 x1 h9 y35 ff1 fs5 fc0 sc0 ls1 ws0">neering,<span class="_ _f"> </span>University<span class="_ _f"> </span>of<span class="_ _f"> </span>Maryland,<span class="_ _9"> </span>College<span class="_ _f"> </span>Park,<span class="_ _f"> </span>MD<span class="_ _9"> </span>20742<span class="_ _9"> </span>USA<span class="_ _f"> </span>(e-mail:</div><div class="t m0 x1 h9 y36 ff1 fs5 fc0 sc0 ls1 ws0">bebewang@umd.edu;<span class="_ _0"> </span>kjrliu@umd.edu).</div><div class="t m0 x8 h9 y37 ff1 fs5 fc0 sc0 ls1 ws0">Color<span class="_ _0"> </span>versions<span class="_ _0"> </span>of<span class="_ _0"> </span>one<span class="_ _d"> </span>or<span class="_ _1"> </span>more<span class="_ _0"> </span>of<span class="_ _d"> </span>the<span class="_ _1"> </span>&#64257;gures<span class="_ _d"> </span>in<span class="_ _1"> </span>this<span class="_ _0"> </span>paper<span class="_ _d"> </span>are<span class="_ _1"> </span>available<span class="_ _1"> </span>online</div><div class="t m0 x1 h9 y38 ff1 fs5 fc0 sc0 ls1 ws0">at<span class="_ _d"> </span>http://ieeexplore.ieee.org.</div><div class="t m0 x8 h9 y39 ff1 fs5 fc0 sc0 ls1 ws0">Digital<span class="_ _d"> </span>Object<span class="_ _d"> </span>Identi&#64257;er<span class="_ _0"> </span>10.1109/JSTSP.2010.2093210</div><div class="t m0 x9 h9 y3a ff1 fs5 fc0 sc0 ls1 ws0">Fig.<span class="_ _d"> </span>1.<span class="_ _5"> </span>Spectrum<span class="_ _d"> </span>usage<span class="_ _d"> </span>[5].</div><div class="t m0 xa h7 y3b ff1 fs4 fc0 sc0 ls1 ws0">namic<span class="_ _f"> </span>spectrum<span class="_ _9"> </span>access<span class="_ _9"> </span>(DSA)<span class="_ _9"> </span>networks,<span class="_ _f"> </span>to<span class="_ _9"> </span>utilize<span class="_ _9"> </span>the<span class="_ _9"> </span>spec-</div><div class="t m0 xa h7 y3c ff1 fs4 fc0 sc0 ls1 ws0">trum<span class="_ _e"> </span>more<span class="_ _e"> </span>ef<span class="_ _3"></span>&#64257;ciently<span class="_ _e"> </span>in<span class="_ _e"> </span>an<span class="_ _e"> </span>opportunistic<span class="_ _e"> </span>fashion<span class="_ _e"> </span>without<span class="_ _d"> </span>inter-</div><div class="t m0 xa h7 y3d ff1 fs4 fc0 sc0 ls1 ws0">fering<span class="_ _7"> </span>with<span class="_ _b"> </span>the<span class="_ _b"> </span>primary<span class="_ _7"> </span>users.<span class="_ _b"> </span>It<span class="_ _b"> </span>is<span class="_ _b"> </span>de&#64257;ned<span class="_ _7"> </span>as<span class="_ _b"> </span>a<span class="_ _b"> </span>radio<span class="_ _7"> </span>that<span class="_ _b"> </span>can</div><div class="t m0 xa h7 y3e ff1 fs4 fc0 sc0 ls1 ws0">change<span class="_ _7"> </span>its<span class="_ _7"> </span>transmitter<span class="_ _e"> </span>parameters<span class="_ _b"> </span>according<span class="_ _e"> </span>to<span class="_ _7"> </span>the<span class="_ _7"> </span>interactions</div><div class="t m0 xa h7 y3f ff1 fs4 fc0 sc0 ls1 ws0">with<span class="_ _b"> </span>the<span class="_ _c"> </span>en<span class="_ _3"></span>vironment<span class="_ _c"> </span>in<span class="_ _c"> </span>which<span class="_ _b"> </span>it<span class="_ _c"> </span>operates<span class="_ _b"> </span>[3].<span class="_ _c"> </span>It<span class="_ _c"> </span>differs<span class="_ _b"> </span>from</div><div class="t m0 xa h7 y40 ff1 fs4 fc0 sc0 ls1 ws0">con<span class="_ _3"></span>ventional<span class="_ _b"> </span>radio<span class="_ _7"> </span>devices<span class="_ _b"> </span>in<span class="_ _7"> </span>that<span class="_ _c"> </span>a<span class="_ _b"> </span>cogniti<span class="_ _2"></span>ve<span class="_ _7"> </span>radio<span class="_ _b"> </span>can<span class="_ _b"> </span>equip</div><div class="t m0 xa h7 y41 ff1 fs4 fc0 sc0 ls1 ws0">users<span class="_ _f"> </span>with<span class="_ _f"> </span><span class="ff4">cognitive<span class="_ _c"> </span>capability<span class="_ _f"> </span></span>and<span class="_ _f"> </span><span class="ff4">recon&#64257;gur<span class="_ _3"></span>ability<span class="_ _f"> </span><span class="ff1">[4],<span class="_ _f"> </span>[5].</span></span></div><div class="t m0 xa h7 y42 ff1 fs4 fc0 sc0 ls1 ws0">Cognitiv<span class="_ _3"></span>e<span class="_ _e"> </span>capability<span class="_ _e"> </span>refers<span class="_ _d"> </span>to<span class="_ _e"> </span>the<span class="_ _e"> </span>ability<span class="_ _d"> </span>to<span class="_ _e"> </span>sense<span class="_ _e"> </span>and<span class="_ _d"> </span>gather<span class="_ _e"> </span>in-</div><div class="t m0 xa h7 y43 ff1 fs4 fc0 sc0 ls1 ws0">formation<span class="_ _e"> </span>from<span class="_ _e"> </span>the<span class="_ _d"> </span>surrounding<span class="_ _e"> </span>environment,<span class="_ _d"> </span>such<span class="_ _e"> </span>as<span class="_ _e"> </span>informa-</div><div class="t m0 xa h7 y44 ff1 fs4 fc0 sc0 ls1 ws0">tion<span class="_ _e"> </span>about<span class="_ _7"> </span>transmission<span class="_ _e"> </span>frequency<span class="_ _3"></span>,<span class="_ _e"> </span>bandwidth,<span class="_ _7"> </span>po<span class="_ _3"></span>wer,<span class="_ _e"> </span>modula-</div><div class="t m0 xa h7 y45 ff1 fs4 fc0 sc0 ls1 ws0">tion,<span class="_ _e"> </span>etc.<span class="_ _7"> </span>W<span class="_ _3"></span>ith<span class="_ _7"> </span>this<span class="_ _7"> </span>capability<span class="_ _3"></span>,<span class="_ _e"> </span>secondary<span class="_ _7"> </span>users<span class="_ _7"> </span>can<span class="_ _e"> </span>identify<span class="_ _7"> </span>the</div><div class="t m0 xa h7 y46 ff1 fs4 fc0 sc0 ls1 ws0">best<span class="_ _7"> </span>available<span class="_ _7"> </span>spectrum.<span class="_ _7"> </span>Recon&#64257;gurability<span class="_ _b"> </span>refers<span class="_ _b"> </span>to<span class="_ _b"> </span>the<span class="_ _7"> </span>ability</div><div class="t m0 xa h7 y47 ff1 fs4 fc0 sc0 ls1 ws0">to<span class="_ _f"> </span>rapidly<span class="_ _9"> </span>adapt<span class="_ _9"> </span>the<span class="_ _9"> </span>operational<span class="_ _9"> </span>parameters<span class="_ _9"> </span>according<span class="_ _9"> </span>to<span class="_ _9"> </span>the</div><div class="t m0 xa h7 y48 ff1 fs4 fc0 sc0 ls1 ws0">sensed<span class="_ _0"> </span>information<span class="_ _d"> </span>in<span class="_ _0"> </span>order<span class="_ _0"> </span>to<span class="_ _d"> </span>achie<span class="_ _3"></span>ve<span class="_ _0"> </span>the<span class="_ _d"> </span>optimal<span class="_ _0"> </span>performance.</div><div class="t m0 xa h7 y49 ff1 fs4 fc0 sc0 ls1 ws0">By<span class="_ _7"> </span>exploiting<span class="_ _e"> </span>the<span class="_ _7"> </span>spectrum<span class="_ _7"> </span>in<span class="_ _7"> </span>an<span class="_ _e"> </span>opportunistic<span class="_ _7"> </span>fashion,<span class="_ _7"> </span>cogni-</div><div class="t m0 xa h7 y4a ff1 fs4 fc0 sc0 ls1 ws0">tiv<span class="_ _3"></span>e<span class="_ _d"> </span>radio<span class="_ _d"> </span>enables<span class="_ _d"> </span>secondary<span class="_ _d"> </span>users<span class="_ _d"> </span>to<span class="_ _d"> </span>sense<span class="_ _d"> </span>which<span class="_ _d"> </span>portion<span class="_ _d"> </span>of<span class="_ _d"> </span>the</div><div class="t m0 xa h7 y4b ff1 fs4 fc0 sc0 ls1 ws0">spectrum<span class="_ _7"> </span>are<span class="_ _7"> </span>a<span class="_ _3"></span>vailable,<span class="_ _7"> </span>select<span class="_ _e"> </span>the<span class="_ _7"> </span>best<span class="_ _7"> </span>av<span class="_ _3"></span>ailable<span class="_ _7"> </span>channel,<span class="_ _7"> </span>coor-</div><div class="t m0 xa h7 y4c ff1 fs4 fc0 sc0 ls1 ws0">dinate<span class="_ _d"> </span>spectrum<span class="_ _d"> </span>access<span class="_ _d"> </span>with<span class="_ _e"> </span>other<span class="_ _d"> </span>users,<span class="_ _d"> </span>and<span class="_ _d"> </span>vacate<span class="_ _d"> </span>the<span class="_ _d"> </span>channel</div><div class="t m0 xa h7 y4d ff1 fs4 fc0 sc0 ls1 ws0">when<span class="_ _e"> </span>a<span class="_ _e"> </span>primary<span class="_ _d"> </span>user<span class="_ _e"> </span>reclaims<span class="_ _e"> </span>the<span class="_ _e"> </span>spectrum<span class="_ _d"> </span>usage<span class="_ _e"> </span>right.</div><div class="t m0 xb h7 y4e ff1 fs4 fc0 sc0 ls1 ws0">Considering<span class="_ _e"> </span>the<span class="_ _e"> </span>more<span class="_ _7"> </span>&#64258;exible<span class="_ _e"> </span>and<span class="_ _e"> </span>comprehensi<span class="_ _3"></span>ve<span class="_ _e"> </span>use<span class="_ _7"> </span>of<span class="_ _e"> </span>the</div><div class="t m0 xa h7 y4f ff1 fs4 fc0 sc0 ls1 ws0">spectrum<span class="_ _f"> </span>resources,<span class="_ _f"> </span>especially<span class="_ _f"> </span>when<span class="_ _f"> </span>secondary<span class="_ _9"> </span>users<span class="_ _f"> </span>coexist</div><div class="t m0 xa h7 y50 ff1 fs4 fc0 sc0 ls1 ws0">with<span class="_ _d"> </span>primary<span class="_ _e"> </span>users,<span class="_ _d"> </span>traditional<span class="_ _d"> </span>spectrum<span class="_ _e"> </span>allocation<span class="_ _d"> </span>schemes<span class="_ _e"> </span>[6]</div><div class="t m0 xa h7 y51 ff1 fs4 fc0 sc0 ls1 ws0">and<span class="_ _f"> </span>spectrum<span class="_ _f"> </span>access<span class="_ _f"> </span>protocols<span class="_ _9"> </span>may<span class="_ _f"> </span>no<span class="_ _f"> </span>longer<span class="_ _f"> </span>be<span class="_ _9"> </span>applicable.</div><div class="t m0 xa h7 y52 ff1 fs4 fc0 sc0 ls1 ws0">New<span class="_ _7"> </span>spectrum<span class="_ _b"> </span>management<span class="_ _b"> </span>approaches<span class="_ _c"> </span>need<span class="_ _b"> </span>to<span class="_ _b"> </span>be<span class="_ _b"> </span>developed</div><div class="t m0 xa h7 y53 ff1 fs4 fc0 sc0 ls1 ws0">to<span class="_ _7"> </span>solve<span class="_ _7"> </span>new<span class="_ _7"> </span>challenges<span class="_ _b"> </span>in<span class="_ _7"> </span>research<span class="_ _b"> </span>related<span class="_ _7"> </span>to<span class="_ _b"> </span>cogniti<span class="_ _3"></span>ve<span class="_ _7"> </span>radio,</div><div class="t m0 xa h7 y54 ff1 fs4 fc0 sc0 ls1 ws0">speci&#64257;cally<span class="_ _3"></span>,<span class="_ _1"> </span>in<span class="_ _0"> </span>spectrum<span class="_ _d"> </span>sensing<span class="_ _1"> </span>and<span class="_ _0"> </span>dynamic<span class="_ _0"> </span>spectrum<span class="_ _d"> </span>sharing.</div><div class="t m0 xb h7 y55 ff1 fs4 fc0 sc0 ls1 ws0">As<span class="_ _7"> </span>primary<span class="_ _7"> </span>users<span class="_ _7"> </span>have<span class="_ _e"> </span>priority<span class="_ _b"> </span>in<span class="_ _7"> </span>using<span class="_ _7"> </span>the<span class="_ _7"> </span>spectrum,<span class="_ _7"> </span>when</div><div class="t m0 xa h7 y56 ff1 fs4 fc0 sc0 ls1 ws0">secondary<span class="_ _b"> </span>users<span class="_ _b"> </span>coexist<span class="_ _b"> </span>with<span class="_ _b"> </span>primary<span class="_ _c"> </span>users,<span class="_ _b"> </span>they<span class="_ _b"> </span>hav<span class="_ _2"></span>e<span class="_ _b"> </span>to<span class="_ _b"> </span>per-</div><div class="t m0 xa h7 y57 ff1 fs4 fc0 sc0 ls1 ws0">form<span class="_ _b"> </span>real-time<span class="_ _7"> </span>wideband<span class="_ _b"> </span>monitoring<span class="_ _b"> </span>of<span class="_ _b"> </span>the<span class="_ _b"> </span>licensed<span class="_ _b"> </span>spectrum</div><div class="t m0 xa h7 y58 ff1 fs4 fc0 sc0 ls1 ws0">to<span class="_ _e"> </span>be<span class="_ _7"> </span>used.<span class="_ _e"> </span>When<span class="_ _e"> </span>secondary<span class="_ _7"> </span>users<span class="_ _e"> </span>are<span class="_ _7"> </span>allo<span class="_ _2"></span>wed<span class="_ _e"> </span>to<span class="_ _7"> </span>transmit<span class="_ _e"> </span>data</div><div class="t m0 xa h7 y59 ff1 fs4 fc0 sc0 ls1 ws0">simultaneously<span class="_ _f"> </span>with<span class="_ _c"> </span>a<span class="_ _f"> </span>primary<span class="_ _f"> </span>user<span class="_ _3"></span>,<span class="_ _f"> </span>interference<span class="_ _f"> </span>temperature</div><div class="t m0 xa h7 y5a ff1 fs4 fc0 sc0 ls1 ws0">limit<span class="_ _e"> </span>should<span class="_ _e"> </span>not<span class="_ _e"> </span>be<span class="_ _e"> </span>violated<span class="_ _e"> </span>[7].<span class="_ _e"> </span>If<span class="_ _e"> </span>secondary<span class="_ _e"> </span>users<span class="_ _e"> </span>are<span class="_ _e"> </span>only<span class="_ _7"> </span>al-</div><div class="t m0 xa h7 y5b ff1 fs4 fc0 sc0 ls1 ws0">lowed<span class="_ _1"> </span>to<span class="_ _d"> </span>transmit<span class="_ _0"> </span>when<span class="_ _0"> </span>the<span class="_ _d"> </span>primary<span class="_ _0"> </span>users<span class="_ _0"> </span>are<span class="_ _d"> </span>not<span class="_ _0"> </span>using<span class="_ _0"> </span>the<span class="_ _d"> </span>spec-</div><div class="t m0 xa h7 y5c ff1 fs4 fc0 sc0 ls1 ws0">trum,<span class="_ _e"> </span>the<span class="_ _2"></span>y<span class="_ _d"> </span>need<span class="_ _e"> </span>to<span class="_ _e"> </span>be<span class="_ _d"> </span>aware<span class="_ _d"> </span>of<span class="_ _e"> </span>the<span class="_ _e"> </span>primary<span class="_ _d"> </span>users&#8217;<span class="_ _e"> </span>reappearance</div><div class="t m0 xa h7 y5d ff1 fs4 fc0 sc0 ls1 ws0">through<span class="_ _d"> </span>various<span class="_ _d"> </span>detection<span class="_ _e"> </span>techniques,<span class="_ _d"> </span>such<span class="_ _e"> </span>as<span class="_ _d"> </span>energy<span class="_ _d"> </span>detection,</div><div class="t m0 xa h7 y5e ff1 fs4 fc0 sc0 ls1 ws0">feature<span class="_ _d"> </span>detection,<span class="_ _0"> </span>matched<span class="_ _d"> </span>&#64257;ltering<span class="_ _d"> </span>and<span class="_ _d"> </span>coherent<span class="_ _0"> </span>detection.<span class="_ _d"> </span>Due</div><div class="t m0 xa h7 y5f ff1 fs4 fc0 sc0 ls1 ws0">to<span class="_ _d"> </span>noise<span class="_ _d"> </span>uncertainty<span class="_ _3"></span>,<span class="_ _d"> </span>shadowing,<span class="_ _d"> </span>and<span class="_ _d"> </span>multipath<span class="_ _d"> </span>effect,<span class="_ _d"> </span>detection</div><div class="t m0 xa h7 y60 ff1 fs4 fc0 sc0 ls1 ws0">performance<span class="_ _7"> </span>of<span class="_ _7"> </span>single<span class="_ _7"> </span>user<span class="_ _7"> </span>sensing<span class="_ _7"> </span>is<span class="_ _b"> </span>pretty<span class="_ _7"> </span>limited.<span class="_ _7"> </span>Coopera-</div><div class="t m0 xa h7 y61 ff1 fs4 fc0 sc0 ls1 ws0">tiv<span class="_ _3"></span>e<span class="_ _7"> </span>sensing<span class="_ _7"> </span>has<span class="_ _7"> </span>been<span class="_ _7"> </span>considered<span class="_ _7"> </span>ef<span class="_ _3"></span>fective<span class="_ _e"> </span>in<span class="_ _7"> </span>improving<span class="_ _e"> </span>detec-</div><div class="t m0 xc h9 y62 ff1 fs5 fc0 sc0 ls1 ws0">1932-4553/$26.00<span class="_ _d"> </span>&#169;<span class="_ _d"> </span>2011<span class="_ _e"> </span>IEEE</div><div class="t m0 xd ha y63 ff5 fs7 fc0 sc0 ls1 ws0">Downloaded from https://iranpaper.ir</div><div class="t m0 xe hb y64 ff6 fs8 fc0 sc0 ls1 ws0">https://www.tarjomano.com/order</div></div><div class="pi" data-data='{"ctm":[1.616162,0.000000,0.000000,1.616162,0.000000,0.000000]}'></div></div> </body> </html>
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