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From the mathematic expression, we can see that sidelobe power of multi-band orthogonal frequency-division multiplexing (MB-OFDM) signal is a function of the data symbols loaded on the sub-carriers. Through the derivation of the minimum of the function, relationships among data symbols, which help to suppress sidelobes, are obtained. Two types of methods, referred as sub-carrier adding (SA) method...
Two points need to be considered on power loading policy of cognitive radio (CR) systems. The first is to maximize the channel capacity over the given frequency band, which is detected usable for CR systems. The second is the out-of-band interference suppression of the CR systems. In the paper based on the mathematical expression of the interference power caused by MB-OFDM based CR systems, the relationship...
Cognitive radio systems offer the opportunity to improve spectrum utilization while avoiding the interference to primary users. Secondary users must be aware of interference caused to primary users. Therefore cognitive radio network should take primary users into account and control their transmission power. This paper focuses on the coverage analysis of cognitive radio network and finds its coverage...
Cognitive radio systems offer the opportunity to improve spectrum utilization while avoiding the interference to primary users. On the one hand, secondary users must be aware of the interference caused to primary users. Therefore, cognitive radio network should control their transmission power. On the other hand, the interference from primary network may degrade the performance of cognitive network...
A mathematical expression of side-band interferences caused by sub-carriers of multi-band (MB)-OFDM UWB based cognitive radio is derived. Based on this expression, the constraint relationship among transmitted symbols, which is satisfied to suppress the interferences, is obtained. Combined with this constraint, the design process of a type of LDPC-like modulation scheme is described. With modulation...
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