Random Aerial Beamforming for Underlay Cognitive Radio with Exposed Secondary Users
In this paper, we introduce the exposed secondary users problem in underlay cognitive radio systems, where both the secondary-to-primary and primary-to-secondary channels have a Line-of-Sight (LoS) component. Based on a Rician model for the LoS channels, we show, analytically and numerically, that L...
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| التنسيق: | article |
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2016
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| الوصول للمادة أونلاين: | http://hdl.handle.net/11073/8674 |
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| _version_ | 1864513437179052033 |
|---|---|
| author | Alaa, Ahmed M. |
| author2 | Ismail, Mahmoud H. Tawfik, Hazim |
| author2_role | author author |
| author_facet | Alaa, Ahmed M. Ismail, Mahmoud H. Tawfik, Hazim |
| author_role | author |
| dc.creator.none.fl_str_mv | Alaa, Ahmed M. Ismail, Mahmoud H. Tawfik, Hazim |
| dc.date.none.fl_str_mv | 2016-11-30T10:43:31Z 2016-11-30T10:43:31Z 2016 |
| dc.format.none.fl_str_mv | application/pdf |
| dc.identifier.none.fl_str_mv | Alaa, Ahmed M., Mahmoud H. Ismail, and Hazim Tawfik. "Random Aerial Beamforming for Underlay Cognitive Radio with Exposed Secondary Users." IEEE Transactions on Vehicular Technology 65, no. 7 (2016): 5364-5383. 0018-9545 http://hdl.handle.net/11073/8674 10.1109/TVT.2015.2466636 |
| dc.language.none.fl_str_mv | en_US |
| dc.publisher.none.fl_str_mv | IEEE Vehicular Technology Society |
| dc.relation.none.fl_str_mv | http://dx.doi.org/10.1109/TVT.2015.2466636 |
| dc.subject.none.fl_str_mv | Aerial degrees of freedom cognitive radio dumb antennas line-of-sight channels multiuser diversity underlay cognitive radio |
| dc.title.none.fl_str_mv | Random Aerial Beamforming for Underlay Cognitive Radio with Exposed Secondary Users |
| dc.type.none.fl_str_mv | Preprint Peer-Reviewed info:eu-repo/semantics/publishedVersion info:eu-repo/semantics/article |
| description | In this paper, we introduce the exposed secondary users problem in underlay cognitive radio systems, where both the secondary-to-primary and primary-to-secondary channels have a Line-of-Sight (LoS) component. Based on a Rician model for the LoS channels, we show, analytically and numerically, that LoS interference hinders the achievable secondary user capacity when interference constraints are imposed at the primary user receiver. This is caused by the poor dynamic range of the interference channels fluctuations when a dominant LoS component exists. In order to improve the capacity of such system, we propose to use an Electronically Steerable Parasitic Array Radiator (ESPAR) antenna at the secondary terminals. An ESPAR antenna involves a single RF chain and has a reconfigurable radiation pattern that is controlled by assigning arbitrary weights to M orthonormal basis radiation patterns via altering a set of reactive loads. By viewing the orthonormal patterns as multiple virtual dumb antennas, we randomly vary their weights over time creating artificial channel fluctuations that can perfectly eliminate the undesired impact of LoS interference. This scheme is termed as Random Aerial Beamforming (RAB), and is well suited for compact and low cost mobile terminals as it uses a single RF chain. Moreover, we investigate the exposed secondary users problem in a multiuser setting, showing that LoS interference hinders multiuser interference diversity and affects the growth rate of the SU capacity as a function of the number of users. Using RAB, we show that LoS interference can actually be exploited to improve multiuser diversity by boosting the effective number of users. |
| format | article |
| id | aus_79bb85a5af6141c50c1ac15f6ecb6414 |
| identifier_str_mv | Alaa, Ahmed M., Mahmoud H. Ismail, and Hazim Tawfik. "Random Aerial Beamforming for Underlay Cognitive Radio with Exposed Secondary Users." IEEE Transactions on Vehicular Technology 65, no. 7 (2016): 5364-5383. 0018-9545 10.1109/TVT.2015.2466636 |
| language_invalid_str_mv | en_US |
| network_acronym_str | aus |
| network_name_str | aus |
| oai_identifier_str | oai:repository.aus.edu:11073/8674 |
| publishDate | 2016 |
| publisher.none.fl_str_mv | IEEE Vehicular Technology Society |
| repository.mail.fl_str_mv | |
| repository.name.fl_str_mv | |
| repository_id_str | |
| spelling | Random Aerial Beamforming for Underlay Cognitive Radio with Exposed Secondary UsersAlaa, Ahmed M.Ismail, Mahmoud H.Tawfik, HazimAerial degrees of freedomcognitive radiodumb antennasline-of-sight channelsmultiuser diversityunderlay cognitive radioIn this paper, we introduce the exposed secondary users problem in underlay cognitive radio systems, where both the secondary-to-primary and primary-to-secondary channels have a Line-of-Sight (LoS) component. Based on a Rician model for the LoS channels, we show, analytically and numerically, that LoS interference hinders the achievable secondary user capacity when interference constraints are imposed at the primary user receiver. This is caused by the poor dynamic range of the interference channels fluctuations when a dominant LoS component exists. In order to improve the capacity of such system, we propose to use an Electronically Steerable Parasitic Array Radiator (ESPAR) antenna at the secondary terminals. An ESPAR antenna involves a single RF chain and has a reconfigurable radiation pattern that is controlled by assigning arbitrary weights to M orthonormal basis radiation patterns via altering a set of reactive loads. By viewing the orthonormal patterns as multiple virtual dumb antennas, we randomly vary their weights over time creating artificial channel fluctuations that can perfectly eliminate the undesired impact of LoS interference. This scheme is termed as Random Aerial Beamforming (RAB), and is well suited for compact and low cost mobile terminals as it uses a single RF chain. Moreover, we investigate the exposed secondary users problem in a multiuser setting, showing that LoS interference hinders multiuser interference diversity and affects the growth rate of the SU capacity as a function of the number of users. Using RAB, we show that LoS interference can actually be exploited to improve multiuser diversity by boosting the effective number of users.IEEE Vehicular Technology Society2016-11-30T10:43:31Z2016-11-30T10:43:31Z2016PreprintPeer-Reviewedinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfAlaa, Ahmed M., Mahmoud H. Ismail, and Hazim Tawfik. "Random Aerial Beamforming for Underlay Cognitive Radio with Exposed Secondary Users." IEEE Transactions on Vehicular Technology 65, no. 7 (2016): 5364-5383.0018-9545http://hdl.handle.net/11073/867410.1109/TVT.2015.2466636en_UShttp://dx.doi.org/10.1109/TVT.2015.2466636oai:repository.aus.edu:11073/86742024-08-22T12:08:13Z |
| spellingShingle | Random Aerial Beamforming for Underlay Cognitive Radio with Exposed Secondary Users Alaa, Ahmed M. Aerial degrees of freedom cognitive radio dumb antennas line-of-sight channels multiuser diversity underlay cognitive radio |
| status_str | publishedVersion |
| title | Random Aerial Beamforming for Underlay Cognitive Radio with Exposed Secondary Users |
| title_full | Random Aerial Beamforming for Underlay Cognitive Radio with Exposed Secondary Users |
| title_fullStr | Random Aerial Beamforming for Underlay Cognitive Radio with Exposed Secondary Users |
| title_full_unstemmed | Random Aerial Beamforming for Underlay Cognitive Radio with Exposed Secondary Users |
| title_short | Random Aerial Beamforming for Underlay Cognitive Radio with Exposed Secondary Users |
| title_sort | Random Aerial Beamforming for Underlay Cognitive Radio with Exposed Secondary Users |
| topic | Aerial degrees of freedom cognitive radio dumb antennas line-of-sight channels multiuser diversity underlay cognitive radio |
| url | http://hdl.handle.net/11073/8674 |