Sensing analysis for cognitive radio in multipath and shadowing conditions over composite fading | |
| Author | Rasheed, Haroon |
| Call Number | AIT Diss no.TC-11-04 |
| Subject(s) | Cognitive radio networks Radio resource management (Wireless communications) |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering in Telecommunications, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. TC-11-04 |
| Abstract | This thesis is concerned with the detection of primary user unknown signal in cognitive radio over composite channel modeling. The sensing problem is treated within the framework of energy detection based binary hypothesis testing. In cognitive radio paradigm discovering of free bands to opportunistically utilize the unused or idle licensed spectrum with energy detection is highly regarded as prospective technique. An analytical solution is presented in terms of a new tractable closed-form expression for average detection probability (Pd) using energy detection over generalized-K (Ka) fading channel. It involves the direct integration of modified Bessel and MarcumQ functions product, which seems computationally intractable. However, the expression is obtained in terms of Confluent Hypergeometric function by using series representation of Marcum-Q function. Moreover, truncation error and convergence rate analysis for derived expression are shown to achieve specific significant accuracy. T he adverse impressions of fading can be mitigated by diversity techniques. We derive closed-form infinite series expression of Pd for more general diversity receiver i. e., maximal ratio combiner (MRC) and selection combiner (SC) over Ka compound shadow-fading. Significant performance improvement is achieved in terms of detection under low SNR region and severe shadow-fading situations. In this exercise, use of the PDF based approach and alternative infinite series representations of Marcum-Q function to overcome the mathematical difficulties is indicated. We further investigate the effects of user collaboration in cognitive radio network on energy detection based sensing performance under composite Ka fading. The decision st atistics based on fusion rule is used to analyze the sensing performance with respect to number of cooperating user and detector parameters adjustment. And and OR fusion rules are evaluated for a given targeted Pd and probability of false alarm P1. Considerably, the scheme not only decreases the probabilities of miss-detection (Pm) and P1, but also it reduces sensing time. To enhance the reliability of primary user signal detection and achieve the full diversity gain in cognitive network relay based cooperation is considered. Two user general time division multiple access (TDMA) based relay cooperation operating in the amplify-and-forward (AF) mode with fixed gain over Ka fading is analyzed. Cooperation versus non-cooperation schemes are compared to examine the performance evaluation of spectrum sensing in light, moderate and severe shadowing for practical scenarios. For non-coherent detection, pulse position modulation (PPM) based energy detection is analyzed for spectrum sensing in cognitive radio. We considered numerical formulation and theoretical curves for error probability calculation in compound shadow-fading in addition to additive white Gaussian noise (AWGN). Error probability performance is analyzed in comparison to threshold selection, time bandwidth product and sub intervals duration, hence, provide a basic point of reference for further exploration. The main contribution of this dissertation is to provide a statistical and analytical framework to evaluate the sensing performance using energy detection in composite Ka fading. Furthermore, we compared various conventional and composite fading channels to pave the way of realistic channel modeling for practical system design. The derived expressions are validated and verified for scenarios of practical interest complimented by the simulation model. With these derivations, various aspects of detection in composite fading are treated and unveil more scope of it for spectrum sensing in cognitive radio network. Furthermore, significant reduction in the computational burden is obtained for evaluating systems performance using derived expression. |
| Year | 2011 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. TC-11-04 |
| Type | Dissertation |
| 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) | Ahmed, Kazi M. ;Tripathi, Nitin K ;Sakari, Latva-aho Matti; |
| Scholarship Donor(s) | Higher Education Commission(HEC),Pakistan - AIT Fellowship ; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2011 |