International Journal of Engineering Sciences & Emerging Technologies, April 2012. ISSN: 2231 – 6604 Volume 2, Issue 1, pp: 8-15 ©IJESET  DYNAMIC SPECTRUM SHARING IN WIRELESS COMMUNICATION Mugdha Rathore 1 ,Nipun Kumar Mishra 2 ,Vinay Jain 3 1&3 Depatment of Electronics & Telecommunication Engineering, SSGI, CSVTU, Bhilai. 2 Depatment of Electronics & Telecommunication Engineering, ITGGV, Bilaspur. mugdha06_rathore@yahoo.co.in ABSTRACT Wireless technology is proliferating rapidly and the vision of pervasive wireless computing and Communications offers the promise of many societal and individual benefits. While consumer devices such as cell phones and laptops receive a lot of attention, the impact of wireless technology is much broader. This explosion of wireless applications creates an ever-increasing demand for more radio spectrum, but the radio spectrum has a fixed range that is not much larger and this limited range of the spectrum is major problem in the wireless networks. Spectrum sharing is one method which gives the solution of this problem by shared the limited band of spectrum between the different users. This increases the spectral efficiency of the wireless networks .Dynamic spectrum access is one method of spectrum sharing in which spectrum should be shared by two users i.e. licensed and unlicensed user. The request of unlicensed would be blocked if the spectrum should occupied by the licensees. In this paper we simulated the dynamic spectrum access approach by using hierarchical access model. We also analyzed the blocking probability of secondary users(unlicensed).Blocking should be reduced by applying queueing process and based on queuing model i.e. Erlang model we analyzed the delay probability waiting time waiting probability for secondary user. KEYWORDS: Dynamic Spectrum Access, Opportunistic Spectrum Access, Primary user, Secondary user, Spectrum sensing. Blocking probability. I. INTRODUCTION The utilization of the radio spectrum band is given by some national regulatory bodies. In the U.S., the main authorities for radio spectrum regulation are the Federal Communications Commission (FCC).The FCC’s spectrum policy gives the actual spectrum usage measurements [1] According to spectrum policy radio spectrum divided into many frequency bands, and licenses for the often exclusive usage of these bands are provided to the service operators Depending on the type of radio service that is then provided by the licensees, frequency bands are often idle in many areas, and inefficiently used. In this condition radio sources are not fully utilized, the alternative way for proper utilization of radio spectrum is Dynamic spectrum access or cognitive radio (CR). Standing for the opposite of the current static spectrum management policy, the term dynamic spectrum access has broad connotations that encompass various approaches to spectrum reform. Dynamic spectrum access strategies can be broadly categorized under three models as shown in figure1. In the first type of DSA, spectrum bands are licensed to [2] services for exclusive use. Two approaches have been proposed under this model: Spectrum property rights & Dynamic spectrum allocation. The first approach allows licensees to sell and trade spectrum and to freely choose technology. The aim of second approach is to improve spectrum efficiency through dynamic spectrum assignment by exploiting the spatial and temporal traffic statistics of different services. Open sharing model employs open sharing among peer users as the basis for managing a spectral region.