The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
OFDM‐based cognitive radio systems are spectrally flexible and efficient, but they are vulnerable to intercarrier interference (ICI), especially in high mobility environments. High mobility of the terminal causes large Doppler frequency spread resulting in serious ICI. Such ICI severely degrades the system performance, which is ignored in the existing resource allocation of OFDM‐based cognitive radio...
This paper considers a power minimization problem for Quality-of-Service provisioning in the downlink of multiuser OFDMA-based cognitive radio systems with real-time services by jointly optimizing over subcarrier and power allocation. An average interference constraint is imposed to protect the primary transmission. The optimal solution is obtained by using Lagrange methods. It can be seen that the...
In OFDMA-based Cognitive Radio (CR) systems, how to deal with the time-varying nature of avaliliable spectrum resources has become a hotspot and challenging problem in resource allocation. Traditional resource allocation algorithm can not guarantee proportional rates among non-real-time CR user (CRU) because the number of available subchannels is smaller than the number of CRUs in some OFDM symbol...
In this paper, the adaptive power allocation problem on the downlink of a multiuser orthogonal frequency division multiplexing (OFDM) based cognitive radio (CR) systems with real-time (RT) services is investigated. The objective is to minimize the total transmit power of all CR users with satisfying the minimum bit rate requirements for RT services and limiting the interference to primary users' (PUs)...
In this paper, we study the resource allocation problem for real-time services in OFDMA-based cognitive radio (CR) systems. A novel resource allocation algorithm is proposed to maximize the sum-rate of all CR users while keeping the interference introduced to the primary user (PU) under a specified threshold and at the same time to meet the constant transmission rate for each CR user to guarantee...
Cognitive radio (CR) has the ability to sense the wireless channel and make use of the vacant spectrum bands. One of the main challenges in CR systems lies in striking a balance between the conflicting goals of minimizing the interference to the primary user (PU) and maximizing the performance of all secondary users (SUs). A joint optimization strategy of sensing time and decision thresholds for wideband...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.