tag:blogger.com,1999:blog-1749403077049578138.post7355929632636330441..comments2015-05-27T14:04:51.591+02:00Comments on Spectral Holes: Recent papers on wideband spectrum sensing for cognitive radio sytemsLa vidahttp://www.blogger.com/profile/15643052307264731416noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-1749403077049578138.post-64399911042600987752013-09-02T17:18:25.573+02:002013-09-02T17:18:25.573+02:00While compressive sensing seems to be able to solv...While compressive sensing seems to be able to solve some of the problems related with the ADC limited speed, the problem of the non-linear Power Amplifier remains unaddressed with such solution. Thus, for me, only the cooperative approaches for wideband sensing seem viable.frankhttps://www.blogger.com/profile/16283466535263015864noreply@blogger.comtag:blogger.com,1999:blog-1749403077049578138.post-2389034334903694892010-12-12T22:25:15.287+01:002010-12-12T22:25:15.287+01:00M.Aman,
Cognitive radio is a general concept and...M.Aman, <br /><br />Cognitive radio is a general concept and it is not restricted to vacant TV bands... however the first standards which explicitly use the term "Cognitive Radio" are intended for this spectrum part, hence your confusion. The term "white space" is a cool designation adopted to refer to any hole in the spectrum not being restricted to the television band.<br /><br />Hope this can help you. You can find my email in my webpage, however due to time constraints I do not when/if I will be able to answer your doubts. I recommend you to read some of the many "high level" introductory articles about cognitive radio you can find online.La vidahttps://www.blogger.com/profile/15643052307264731416noreply@blogger.comtag:blogger.com,1999:blog-1749403077049578138.post-16077884039219139552010-12-09T15:44:58.798+01:002010-12-09T15:44:58.798+01:00Hello Gonzalo,
Thank You :) I did search with the...Hello Gonzalo,<br /><br />Thank You :) I did search with the key word you mentioned. I came across a Paper, "Spectrum Sensing with active cognitive systems", which proposes a spectrum sensing technique while the CR is active. I am still confused about a few things,like, are cognitive radios only to operate in vacant TV bands? when they use the term 'White Space', does it only mean vacant TV channels? i also have a few more questions,i was wondering if i can have your email address please? <br /><br />Regards,<br />M.AmanUnknownhttps://www.blogger.com/profile/03306844724491223820noreply@blogger.comtag:blogger.com,1999:blog-1749403077049578138.post-52850722216640372092010-12-09T15:26:17.957+01:002010-12-09T15:26:17.957+01:00Hello Gonzalo,
Thank You :) i did search with ...Hello Gonzalo,<br /><br /> Thank You :) i did search with the key word you mentioned, i came across a paper, " Spectrum Sensing with Active Cognitive Systems" which kind of proposes sensing technique while cognitive radio is active. There is one thing i am still confused about, are cognitive radios only to operate in TV bands? when they use the term 'White Space' does it only mean vacant TV channels? I also have a few more questions in this area, i was wondering if i can have your email address please?<br /><br />Regards,<br />M.AmanUnknownhttps://www.blogger.com/profile/03306844724491223820noreply@blogger.comtag:blogger.com,1999:blog-1749403077049578138.post-32173063265750124952010-12-07T23:50:40.102+01:002010-12-07T23:50:40.102+01:00Hello M.Aman,
this is a good question with a diff...Hello M.Aman,<br /><br />this is a good question with a difficult answer. I will try to answer it without extending so much.<br /><br />On the one hand we have that it is theoretically possible to perform sensing and transmission simultaneously (if your hardware allows full duplex transmission). This can be done, for example:<br />- If you have multiple antennas and you are transmitting only one stream, you can perform the detection in an orthogonal subspace.<br />- If you know certain signal features of the secondary network, such as preambles or pilots, in principle these signals can be subtracted, and detection performed in these cleaned dimensions.<br />- If you know exactly the transmitted waveform, this can be cleaned from the "sensed" signal.<br />- Etc...<br /><br />However, these techniques, even when theoretically possible, they are very difficult to bring into practice. The main reason is that multiple non-idealities exist in a practical system, from the power amplifier, to the ADC... including automatic gain control loops and so on. This makes extremely difficult to completely clean certain dimensions existing always a leakage from the secondary signal in the signal used in the detection process. This hinders detection of primary systems with very low SNR.<br /><br />Summing up, the answer is that it is theoretically possible, but challenging in practice. However, quite a bunch of papers have already been published in this topic. I recommend you to start with a search with the keywords: <a href="http://www.google.com/search?ie=UTF-8&q=%22quiet+period%22+cognitive+radio+sensing" rel="nofollow">"quiet period" cognitive radio sensing</a>.<br /><br />Regards, GonzaloLa vidahttps://www.blogger.com/profile/15643052307264731416noreply@blogger.comtag:blogger.com,1999:blog-1749403077049578138.post-6134570596683562052010-12-07T09:00:58.629+01:002010-12-07T09:00:58.629+01:00Hi...i am also doing research in CR.I wanted to kn...Hi...i am also doing research in CR.I wanted to know if a Cognitive Radio can sense during its transmission on a vacant channel? like, is the CR smart enough to perform sensing and transmission simultaneously?<br /><br />Regards,<br />M.AmanUnknownhttps://www.blogger.com/profile/03306844724491223820noreply@blogger.com