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Dec 1, 2010

Recent papers on wideband spectrum sensing for cognitive radio sytems

Wideband spectrum sensing. In this post I include a list of papers recently published on the topic of wideband detection in cognitive radio. This post complements and updates the survey I did some time ago on wideband spectrum sensing.

A Class of Spectrum-Sensing Schemes for Cognitive Radio Under Impulsive Noise Circumstances: Structure and Performance in Nonfading and Fading Environments, by HG Kang, I Song, S Yoon, YH Kim. This paper exploits a nonlinear diversity-combining strategy together with the generalized likelihood ratio test detectors on each of the antenna branches.

A Parallel Cooperative Spectrum Sensing in Cognitive Radio Networks. In this work S. Xie, Y. Liu, Y. Zhang and R. Yu propose a sensing scheme in which several secondary users are selected to perform sensing in different channels. They present an analytical model to investigate the tradeoff between the transmitted data and the sensing overhead, which results into a throughput maximization problem.

Multiantenna spectrum sensing: The case of wideband rank-one primary signals. In this work D Ramırez, J Via and I Santamaria derive multiantenna detector based on the asymptotic likelihood under the asumptions of a wideband rank-one signal under spatially uncorrelated noise with equal or different power spectral densities.

Distributed Compressive Spectrum Sensing in Cooperative Multihop Cognitive Networks. In this paper F Zeng, C Li, Z Tian present a cooperative approach to wideband spectrum sensing. Their scheme utilizes a compressive sampling mechanism which exploits the signal sparsity induced by network spectrum under-utilization by enforcing consensus among local spectral estimates.

A Wideband Spectrum Sensing Method for Cognitive Radio using Sub-Nyquist Sampling. In this preprint M Rashidi, K Haghighi, A Owrang and M Viberg present a wideband spectrum sensing scheme that utilizes a sub-Nyquist sampling in order to reconstruct the correlation matrix. This method does not require the knowledge of signal properties mitigating the uncertainty problem. Also by Moslem Rashidi is this long preprint (maybe a book chapter?): Non-uniform sampling and reconstruction of multi-band signals and its application in wideband spectrum sensing of cognitive radio. It may be an useful introduction to the topic.

On the use of Compressive Sampling for Wide-band Spectrum Sensing by D. Sundman, S. Chatterjee and M. Skoglund. For wideband signals sampling at the Nyquist rate is a major challenge. In this work they propose a wideband detection scheme of multiple simultaneous signals using sub-Nyquist sampling rates. This work is extended to incorporate memory from previous slots in slow varying scenarios.

Evidence Theory Based Cooperative Spectrum Sensing with Efficient Quantization Method in Cognitive Radio. In this work N. Nguyen-Thanh and I. Koo study an enhanced scheme for cooperative spectrum sensing based on efficient quantization and the Dempster-Shafer Theory of Evidence. They propose an effective quantizer for the sensing data which takes advantage of special properties of the statistic distribution for different signal-to-noise ratios of the primary signal, hence reducing the required bandwidth for the reporting channel occupancy.

Adaptive Spectrum Sensing and learning in Cognitive Radio Networks by A. Taherpour, S. Gazor and A. Taherpour. This paper proposes an iterative primary user activity detection algorithm for a wideband frequency range using a Markov Model (MM) with two states to model the activity of the primary users.

If you know any additional paper related to wideband sensing which has been recently published you can leave a comment with the link.

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Blogger M said...

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?


December 7, 2010 at 9:00 AM  
Blogger Gonzalo said...

Hello M.Aman,

this is a good question with a difficult answer. I will try to answer it without extending so much.

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:
- If you have multiple antennas and you are transmitting only one stream, you can perform the detection in an orthogonal subspace.
- 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.
- If you know exactly the transmitted waveform, this can be cleaned from the "sensed" signal.
- Etc...

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.

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: "quiet period" cognitive radio sensing.

Regards, Gonzalo

December 7, 2010 at 11:50 PM  
Blogger M said...

Hello Gonzalo,

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?


December 9, 2010 at 3:26 PM  
Blogger M said...

Hello Gonzalo,

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?


December 9, 2010 at 3:44 PM  
Blogger Gonzalo said...


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.

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.

December 12, 2010 at 10:25 PM  
Blogger frank said...

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.

September 2, 2013 at 5:18 PM  

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