應用于實時認知無線網絡的頻譜決策方案.pdf

1、Fast and reliable wireless communication depends mainly on the available frequency bandwidth．Cognitive radio has the ability to reliably and autonomously identify unused frequency bands.With cognitive radio technology pr

2、omising to utilize spectrum bands．The question still remains；can it utilize the spectrum bands efficiently with the increasing scarcity of the spectrum?
　　The growing number of the wireless users brings challenges suc

3、h as degradation of the quality of service of the real-time applications caused by the primary user activity andinterference from increasing number of Cognitive radio users．
　　When primary users appear in the spectrum

4、 band，CR users need to move to a new availableband，resulting in a temporary communication break．To solve this problem，that multiple noncontiguous spectrum bands are assumed．they are simultaneously used for thetransmissio

5、n in the CR network．This method can create a signal that is capable of high data throughput and also immune to the PU activity．Even if a primary user appears in one of thecurrent spectrum bands，the rest of them will main

6、tain current transmissions．
　　Real-time applications need to have more reliable and time invariant communication channels to satisfy strict service requirements，such as delay constraints and sustainable rates．
　　Ho

7、wever,how to maximize the total network capacity is still a crucial problem．The proposed practical spectrum decision scheme aims at improving the quality of service by reducing delay time and data loss which occurs due t

8、o a temporary transmission breakdown．Whenever real-time application CR users fail，to get an available channel with their sustainable rate to continue transmission．They yield a high data loss which makes the QOS more unre

9、liable．The proposed assignation queuing criteria allows real-time users to queueslots for less than one as they wait for available channel to continue transmission．When compared to the tradition spectrum decision，they ar

10、e an improved data loss．
　　The Qos were investigated with the primary user activity performance in MATLAB simulations．When implementing the queuing order criteria we assumed that there was no interference from primary