{"title":"A spectrum handoff scheme based on comprehensive cost in cognitive radio system","authors":"Tianwei Wen, Yafeng Wang, C. Li","doi":"10.1109/VITAE.2014.6934485","DOIUrl":"https://doi.org/10.1109/VITAE.2014.6934485","url":null,"abstract":"In the cognitive radio networks, the spectrum handoff scheme directly determines the system performance. That's to say a handoff scheme that cannot fully uses the information of users and channels will not provide the best choice. In this paper, a spectrum handoff scheme based on comprehensive cost is proposed. By jointly computing multiple factors such as transmission delay, channel bandwidth, SNR and the characteristics of users and so on, we get a Judgment Matrix for channel selection so that we can give consideration to all these factors' influence on the final system performance. In this paper we also set up a cognitive radio scenario to simulate the process and verify our scheme. Comparing with the random access scheme, the simulation results show that our scheme can reduce the probability of spectrum handoff and enhance the throughput capacity significantly and finally result in larger service carrying capacity and lower service drop number.","PeriodicalId":161998,"journal":{"name":"International Conference on Wireless Communications, Vehicular Technology, Information Theory and Aerospace & Electronic Systems","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125136120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Performance improvement of two-hop cooperative relay system under correlated Ricean fadings","authors":"Maja Delibasic, M. Pejanovic","doi":"10.1109/VITAE.2014.6934401","DOIUrl":"https://doi.org/10.1109/VITAE.2014.6934401","url":null,"abstract":"This paper studies performance of two-hop cooperative relaying system employing regenerative decode-and-forward (DF) technique. Infrastructure based relay equipped with dual-polarized antenna is assumed, performing maximal ratio combining of the received signals. Link between the source and the relay is characterized as two correlated and non-identical Ricean fading channels. There is also direct communication between the source and the destination. In order to determine the level of improvement introduced through the implementation of polarization diversity, performances of the considered system are compared with the DF relay system with single antenna relay. The obtained results show that, using polarization diversity, the same BER (Bit Error Rate) values can be obtained with significantly lower SNR (Signal to Noise Ratio), despite a certain level of correlation and power unbalance between the diversity branches. In that manner, compared to the system with no diversity, the total needed transmit power for achieving the same level of system performances is reduced, and thus more energy efficient communication is enabled.","PeriodicalId":161998,"journal":{"name":"International Conference on Wireless Communications, Vehicular Technology, Information Theory and Aerospace & Electronic Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126219072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}