| Author | Banjade, Vesh Raj Sharma |
| Call Number | AIT Thesis no.TC-11-06 |
| Subject(s) | Cognitive radio networks
|
| Note | A thesis submitted in partial fulfillment of the requirements for the
degree of Master of Engineering in
Telecommunications, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. TC-11-06 |
| Abstract | Recent studies have revealed vast underutilization of the statically allocated licensed
spectrum bands across space and time. Cognitive radio (CR) technology is an
evolutionary concept for efficient radio spectrum utilization that performs detection of
the unused bands and temporarily uses them without inflicting any serious interference
to primary user (PU) of such bands. We consider energy detector based PU sensing
using multiple correlated antenna CR deploying a square law combiner operating under
Nakagami-m faded, AWGN corrupted channels from PU to CR. We derive the average
probability of detection explicitly for two, three and four correlated antenna CR and
also illustrate a generalized approach for L correlated antennas. We take this scenario
further to a cooperative detection network that has a number of multiple correlated
antenna CRs assuming Nakagami-m faded and AWGN corrupted channels from each
CR to a fusion center (FC) which produces the ultimate decision regarding the spectrum
vacancy. We derive an optimal log-likelihood ratio (LLR) at the FC for two,
three and four antenna CR and generalize the results for any number of antennas. Our
analysis suggests that the existence of correlation among antennas degrades the detection
performance of each individual CR and of the overall cognitive network. However,
the improvement in detection capability due to antenna diversity is more pronounced
than the deterioration in it due to antenna correlation. Hence, antenna diversity is
beneficial for boosting the individual as well as the overall detection capability of cooperative
CRs even in presence of antenna correlation. We next consider an optimal
allocation of the total transmit power of a PU in a bid to maximize the capacity of PU
to base station (BS) such that the m out of N fused probability of detection of PU by
an N number of collaborating CRs is above a certain threshold guaranteeing a reliable
cooperative detection performance. We formulate and solve the problem after proving
it to be convex to analyze the effect of m out of N fusion rule on both the optimal
capacity and the corresponding fused detection probability. The MAJORITY rule has
the best detection probability whereas the OR rule tends to somewhat balance the
tradeoff between high PU capacity and high fused detection probability requirements. |
| Year | 2011 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. TC-11-06 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Telecommunications (TC) |
| Chairperson(s) | Rajatheva, R.M.A.P. ; |
| Examination Committee(s) | Teerapat Sanguankotchakorn;Poompat Saengudomlert; |
| Scholarship Donor(s) | Government of Finland–AIT Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2011 |