DYNAMIC SPECTRUM ACCESS AND SHARING USING 5G IN COGNITIVE RADIO

Transcription

1 DYNAMIC SPECTRUM ACCESS AND SHARING USING 5G IN COGNITIVE RADIO Ms.Sakthi Mahaalaxmi.M UG Scholar, Department of Information Technology, Ms.Sabitha Jenifer.A UG Scholar, Department of Information Technology, Mr.AnandaKumar.H Assistant Professor, Department of Information Technology, Abstract - Spectrum Access and sharing is mainly focused on utilizing the unused spectrum of licensed users, without interference and enlarge the spectrum usage. The frequency spectrum is selected to operate at a given location, at a given period of time to optimize the use of idle spectrum and deny interference with other radios or other system are said to be DSA. CRN focuses majorly towards primary users and this concept is accepted in DSA as the primary users are to be protected, by maximizing the performance of secondary users, considering the metrics of false alarm and missed detection. In order to face the requirements of the probability of missed detection, traditional spectrum sensing techniques can unnecessarily increase the probability of false alarm with opportunistic reuse of spectrum by lowering the ability to influence the spectrum hole. The probability of interference and the new metric of spectrum sensing consider solving this interference and missed detection. In this the secondary users pay to the primary users while accessing the band temporarily. Keywords: Cognitive radio, Dynamic Spectrum Access, Interference aware sensing, Spectrum hole discovery. I.INTRODUCTION: The main concept of cognitive radio is to detect the unused spectrum and try to utilize those free spaces to its maximum utilization. The cognitive radio is otherwise commonly known as intelligent radio as it is dynamically programmed and configured. It consists of the transceiver which automatically detects the unused channels and alters the transmission and reception as needed. The cognitive radio is the open spectrum sharing which avoids the interference with the usage of spectrum sensing that uses the spectrum management technology. The major functionalities of cognitive radio are spectrum sensing, spectrum sharing, spectrum mobility and spectrum management. The basic objective of cognitive radio is to provide better communication at any location and improve the efficiency in spectrum usage. Such a radio network is known as Cognitive Radio Network (CRN). There are two types of frequency spectrum users such as: Primary User (PU) who is non-cognitive and Secondary User (SU) who is cognitive. The PU is the licensed user of the spectrum band and the SU is the unlicensed user who needs to access the unused spectrum band of the licensed user. The CRN has the main concept of utilizing the idle spectrum in the air of the privileged user (Licensed User) by the nonprivileged user (Unlicensed User) with proper negotiation. This improves the use spectrum ISSN: Page 104

2 frequency by reducing the interference with licensed user. The Dynamic Spectrum Access(DSA) is the main application of cognitive radio network which identifies the unused frequency or the white spaces in the spectrum of the primary users for the utilization of the secondary users. The concept mainly focuses on complete utilization of the spectrum frequency to its full potential. It also vitally improves the protection level for the primary users when the spectrum is concurrently used by the secondary users. The main objective of DSA is to prevent the harmful interference made by malicious user and device malfunctioning. In DSA there are three different main functions such as Spectrum awareness, Spectrum access and Cognitive processing. The paper has been discussed with sections as follows: Section 2 describes about the information regarding the cognitive radio with spectrum sensing. Section 3 involves the discussion about the dynamic spectrum access. In Section 4, the new metric for better utilization of spectrum is given. Section 5, details about the proposed metric and section 6 contains the details about the results. In section 7 the conclusion and future progression is given. II. RELATED WORKS: In this section we will survey the literature on the dynamic spectrum access with interference aware spectrum sensing. The dynamic spectrum access and sharing allows the unlicensed users to fill in the white spaces left by the primary users for better usage of the spectrum frequency[1]. In order to make this opportunistic access the main step to be done by the secondary user is to detect the primary user using the spectrum sensing method. The missed detection and false alarm that leads to underutilization of the spectrum is the main issue in spectrum allocation. The spectrum becomes more congested due to the improved growth in the wireless services with huge and growing demand of the consumers for the communications[2]. The static allocation leads to inefficient utilization of the spectrum by producing the empty spectrum hole or white spaces. The DSA is the technique in CRN which adapts to the unused spectrum hole or white spaces which are not under usage in accordance to the circumstance and environmental constraints[3]. There are different schemes and models available for the DSA such as exclusive use model, open sharing model and hierarchical access model. There are two types of CR such as the underlay CR and Overlay CR[4]. The Underlay CR allows the coexistence of the licensed and unlicensed users when the interference level is low which does not affect the primary users. The Overlay CR mitigates the interference allowing concurrent usage by licensed and unlicensed users. The current radio spectrum allocation policy is evaluated with respective to both the technical and economic perspective[5].this evaluation result gives that the current allocation policy is inflexible, obsolete and unsuitable which needs to be altered with new flexible management policy. The nature of channel fading and background noise has the possibility that the signal detector at the unlicensed user makes an inaccurate detection[6],[7]. The fundamental deal between the two errors prevents the detector from operating with small probabilities of false alarm and missed detection[8]. Cognitive Radio is considered as the one possible way for implementing the dynamic spectrum access and sharing[9]. And also the CR has become the common term in research on radio technology where the radios are trying to utilize the free licensed spectrum. In 4G the data rates started with 100Mbps and supposed to reach 1 Gbps at a variable bandwidth of 70MHz[10]. In 5G the data rates are started with 1Gbps and supposed to have without limitation. III. DYNAMIC SPECTRUM ACCESS: The idea of dynamic spectrum access allows the secondary users to use the spectrum hole or white space that are unused by the primary user or the license holder opportunistically in order to improve the utilization of the spectrum frequency. Thus if the secondary users need to gain the opportunistic access ISSN: Page 105

3 to the licensed spectrum they need to sense the spectrum for detecting the presence of the primary user. Due to the nature of channel fading and the background noise the signal detector at the secondary user gives an incorrect detection decision. During sensing if the secondary user falsely claims that the primary user is active then it leads to underutilization of the spectrum frequency. And also if the secondary user fails to detect the presence of the primary licensed user then it leads to missed detection which creates interference to the primary users. Such occurrence of the false alarm and the missed detection are equally undesirable which should be minimized whenever possible. IV. INTERFERENCE AWARE METRIC: The missed detection occurrence leads to interference in the primary user which may not be harmful but it affects the protection measures of the licensed user. Hence the probability of suffering interference during the occurrence of missed detection should be considered. The spectrum hole discovery is another measure that helps in accessing the spectrum opportunistically in order to minimize the issues of missed detection and false alarm. Where γ is the average SINR at the primary user during reception of a packet with M symbols at worst case. Here IP 1 is the probability of causing interference during the presence of the primary and secondary transmitters. As the condition of IP MD ε becomes very protective when the unlicensed user does not interfere with the licensed user, a better metric for improving spectrum utilization can be given as IP MD IP 1 ε, to protect the interference of the primary user by the secondary user having the probability of 1-ε. The secondary user does not interfere with the primary user when this relation is satisfied. B. PROBABILITY OF SPECTRUM HOLE DISCOVERY: It is probable that the secondary user should preferably be allowed to utilize the spectrum as long it does not provide interference to the primary user. A. PROBABILITY OF INTERFERENCE: Normally, a secondary unlicensed user can only transmit if it detects the absence of the primary user after spectrum sensing. Yet in opportunistic spectrum access, a secondary user is allowed to transmit when it does not interfere with the primary user. A secondary user when coming inside the cell should confirm that the primary user can still be able to receive from its transmitter during transmission. At the same time, the transmission in the secondary user should not interfere with the primary licensed receiver that experiences largest interference in such a way that where is the desired SINR threshold. The probability of interference of the secondary user can be therefore defined as Therefore the secondary user holds the spectrum hole in the following cases: Prob(D=0 H 0 ): The primary user is not active and the false alarm regarding the spectru m usage is not made by the secondary user. The probability of spectrum hole discovery in this case is represented as (1-IP FA ) (1- ISSN: Page 106

4 IP E ), where IP E is the probability of spectrum utilization by the primary user. Prob({D=0 H 1 } {γ γ t }): The missed detection is made by the secondary user when the primary user is active, but the secondary user does not interfere with the primary user during transmission such that γ γ t. Thus the probability of spectrum hole discovery can be of the secondary user can be given as the sum of the two probabilities IP SHD = IP MD (1 - IP 1 ) IP E + (1 - IP FA ) (1 - IP E ) The proposed metric can result in improved utilization of the spectrum hole by the secondary unlicensed user with maximization of its transmission opportunities without spoiling the protection of the primary user as discussed in section 4. It also improves the performance of sensing by assuming continuous state of IP 1.Compared to the conventional technique the proposed technique better utilizes the spectrum space with higher value of IP SHD during transmission. VII. CONCLUSIONS AND FUTURE WORK: In this paper initially we have discussed about dynamic spectrum sensing for spectrum utilization by the secondary user. The next part or section tells about the new metric known as the interferenceaware metric which solves the false alarm and missed detection issues with one primary transmitter. In the future, the work includes the same case with multiple transmitter in multicell network having different frequencies. References [1] You-En Lin, Kun-Hsing Liu, and Hung-Yun Hsieh, On Using Interference-Aware Spectrum Sensing for Dynamic Spectrum Access in Cognitive Radio Networks, IEEE TRANSACTIONS ON MOBILE COMPUTING, VOL. 12, NO. 3, MARCH 2013 Fig. 2. Interference-aware metric for dynamic spectrum access V. PROPOSED METHOD: The above discussed problems are due the problems in sensing techniques being used and the signal strength. It has been proposed that the interference-aware metric helps in improving the spectrum hole discovery which deduces the false alarm problem and the interference spectrum sensing allows the reduction in the missed detection. Both the measures are mainly involved in improving the spectrum utilization by the unlicensed users without disturbing the transmission of the primary users. VI. RESULT AND DISCUSSION: [2] Badr Benmammar1, Asma Amraoui1, Francine Krief2, A Survey on Dynamic Spectrum Access Techniques in Cognitive Radio Networks, International Journal of Communication Networks and Information Security (IJCNIS) Vol. 5, No. 2, August 2013 [3] Goutam Ghosh, Prasun Das and Subhajit Chatterjee, Cognitive Radio And Dynamic Spectrum Access A Study, International Journal of Next- Generation Networks (IJNGN) Vol.6, No.1, March 2014 [4] Mehedi Shams Rony, Adrian J Pullin, Design Considerations for 5G Mobile Network, International Journal of Computer Applications ( ) Volume 62 No.10, January 2013 ISSN: Page 107

5 [5] Jide Julius Popoola1, Rex van Olst, A Survey on Dynamic Spectrum Access via Cognitive Radio: Taxonomy, Requirements, and Benefit, Universal Journal of Communications and Network 2(4): 70-85, 2014 [6] T. Yucek and H. Arslan, A Survey of Spectrum Sensing Algorithms for Cognitive Radio Applications, IEEE Comm.Surveys and Tutorials, vol. 11, no. 1, pp , Jan.-Mar [7] D. Datla, A. Wyglinski, and G. Minden, A Spectrum Surveying Framework for Dynamic Spectrum Access Networks, IEEE Trans.Vehicular Technology, vol. 58, no. 8, pp , Oct Energy Detection in Cognitive Radio Networks, IEEE Trans. Wireless Comm., vol. 8, no. 12, pp , Dec [9] Survey on performance analysis of cognitive radio networks Pasi Lassila and Aleksi Penttinen COMNET Department, Helsinki University of Technology,P.O. Box 3000, FIN TKK, Finland January 9, 2009 [10] Dr. Anwar M. Mousa University of Palestine,Gaza- Palestine, Prospective of Fifth Generation Mobile Communications, International Journal of Next-Generation Networks (IJNGN) Vol.4, No.3,September 2012 [8] W. Zhang, R. Mallik, and K. Letaief, Optimization of Cooperative Spectrum Sensing with ISSN: Page 108