Cognitive radio network is discussing how to enhance frequency reuse by allowing the unlicensed users to utilize the frequency bands of licensed users when these bands are not currently being used. Generally speaking, we called these unlicensed users as secondary users and these licensed users as primary users. In order to enhance frequency reuse, the secondary users need to monitor the spectrum continuously to avoid possible interference with the primary users, and once the primary users are found to be active, the secondary users are required to vacate the frequency bands. Therefore, spectrum sensing plays a significant important role in cognitive radio network. There are two probability values associated with spectrum sensing: probability of detection and probability of false alarm. The higher the probability of detection means the better theprimary users are protected. However, from the secondary users¡¦ perspective, the lower the probability of false alarm, the more chances the frequency bands can be reused when it is available, thus the higher the achievable throughput for the secondary network. In this thesis, we study the problem of designing the sensing duration to maximize the achievable throughput for the secondary network under the constraint that the primary user is sufficiently protected. We formulate the sensing-throughput tradeoff problem mathematically, and use energy detection ¡]ED¡^[4] sensing scheme to prove that the formulated problem indeed has oneoptimal sensing time that yields the highest throughput for the secondary network. We also discuss the case of two secondary users with the concept of cooperative systems.

Abstract It¡¦s a radio revolution, Has always been absolute leadership - the China Broadcasting and the traffic professional radio stations, beginning at the third quarter of 2009. For the first time, they stand behind the BEST RADIO (Taipei best 98.9, Taichung best radio 90.3, Hualien best 93.5) according AC Nielsen survey of audio-visual, listening to the population and total listening time is also lagging behind. The writer Study on the long-term observation of engaged in full-time research and development of broadcasting, This made observation of visions and recommendations. Researches have shown, being able to follow the rules of Format radio, at the time of operation, step by step without hesitation, the commercially successful is not too difficult. However, we also feel to, AC Format broadcasting company will program production simplified for digital system, is from which lost some human nature, deny audience self-control of rights. And changed artist characteristics. Broadcasting company decided has social of collective interest and collective hobby. Format radio told audience to listening to of is what, and what they should like. This is worth discussion of issues.

Summary It is the most important divide in 1993, before that, the broadcasting in Taiwan is self-contained and monopolized. The government authorities had made applications of channels open to the public access officially for 10 years since 1993. Early and late, there¡¦re more than 100 low-powered, medium-powered, and high-powered radio stations have established and the amount has reached around 300~350 ones if you count illegal underground broadcasting stations in. That is the highest density and most chaotic area all over the world. Not only variety devices but also new fantastic guise, the broadcasting market in Taiwan with furious and flaming competitions, and each one goes his own way. Because an excess of radio stations, all of them are tired out to operate. Opening up newspapers and TV programs, as a result of high initiative limits, few companies have acceded to the market and competed with each other intensely. Recently years, most mess mediums are in a red. As long as you can talk, you can have a chance to be a DJ. Not going into the program quality, it still has specific audiences. And even more some radio stations are striving for their listeners by showing political standpoints instead of caring about the profit and custom. Therefore, the feature of broadcasting industry of Taiwan is carrying on broadcasting stations¡¦s extremely difficult and tough. The superficial measure of Taiwan is not vast and the population is not multitudinous either, and the social structure between northern and southern part is widely dissimilar. Professor Wang ming-sheng said, the people who live in south part in Taiwan are short of citizen accomplishments, then it makes cultural standings are quite different. By this way, marketing tactics are changing, too. Such as languages, industries, educational standings and elder age level, they are business elements you have to consider. This is the key subject we want to keep researching and making a study constantly. Key words: Format, DAB, Internet Radio

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Texte remanié de: Diss.--Universität Bielefeld, 1994. / Bibliogr. p. 323-333.

Extrait de: Doctoral dissertation--Faculty of social sciences--Rome--Pontifical Gregorian university, 2006. / Bibliogr. p. 69-83.

Texte remanié de: Mémoire--Histoire--Paris 4, 2001. / Bibliogr. p. 259-260. Notes bibliogr.

Thesis (M. Ed.)--York University, 1998. Graduate Programme in Education. / Typescript. Includes bibliographical references (leaves 117-121). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ39232.

Texte remanié de : Thèse de doctorat : Sciences du langage : Paris 13 : 2002. / Bibliogr. p. 165-170. Index.

Proefschrift--Amsterdam. / Published also without thesis note as deel 1 of his Omroep en publiek in Nederland tot 1940. "Literatuur en bronnen in de achterstaande noten opgenomen": p. 224-225.