Cognitive Mesh Network Under Interference from Primary User
Tóm tắt
In a commonly accepted usage scenario, a cognitive radio appears as a secondary user of certain spectrum which is licensed to another, primary system. A prominent example of cognitive system is a mesh network operating under the interference from primary system. For such a scenario, we propose techniques for efficient secondary usage of spectrum, which rely on the adaptive array antenna in order to reduce the interference between the primary and the cognitive system. In order to keep the hardware complexity as small as possible, the number of antennas at each cognitive node should be small. However, with the simplest 2-element linear adaptive array, the created antenna pattern can result in non-optimized pattern between cognitive nodes in the mesh network. In order to solve such a problem, this paper introduces a simple antenna pattern switching where each cognitive node is equipped with three antennas, and tries to select the antenna configuration constituting 2-element linear array with the best antenna pattern for each link. The proposed configuration requires three antennas but only two transceiver chains, which can reduce the hardware complexity. We also introduce 3-element linear array and design a simple procedure to heuristically select the pattern. Our numerical results show that the proposed techniques can significantly increase the available bandwidth and networking connectivity with small complexity when a cognitive mesh network is located inside the communication area of the primary system.
Tài liệu tham khảo
McHenry, M. A. (2005). NSF Spectrum Occupancy Meaurements Project Summary, http://www.sharedspectrum.com, August 2005.
Haykin S. (2005). Cognitive radio: brain empowered wireless communication. IEEE Journal on Selected Areas in Communications 23(2): 201–222
Mitola, J. III. (1999). Cognitive radio for flexible mobile communications. In Proceedings of 6th International Workshop on Mobile Multimedia Communication MoMuC.
Akyildiz I.F., Lee W.Y., Vuran M.C., Mohanty S.H. (2006). Next generation/dynamic spectrum access/cognitive radio wireless networks: A survey. Elsevier Computer Networks 50(13): 2127–2159
Jing X., Mau S., Raychaudhuri D., Matyas R. (2005). Reactive cognitive radio algorithms for Co-existence between IEEE 802.11b and 802.16a networks. IEEE Global Telecommunications Conference (GLOBECOM ’05) 5: 2465–2469
Nishimori, K., Bottega, E., Yomo, H., Popovski, P., Takatori, Y., Prasad, R., & Kubota, S. (2006). Spatial availability for cognitive radio system under directional interference. In Proceedings of 9th International Symposium on Wireless Personal Multimedia Communications (WPMC06).
Monzingo R.A., Miller T.W. (1980). Introduction to adaptive arrays. Hughes Aircraft Company. California, Fullerton
Ichitsubo, S. (1996). 2GHz-band propagation loss prediction in urban areas; Antenna heights ranging from ground to building roof. IEICE Technical Report.
Durgin G., Rappaport T.S. (1998). Basic relationship between multipath angular spread and narrowbandfading in wireless channels. Electronics Letters 34(25): 2431–2432
Kitao K., Ichitsubo S. (2004). Path loss prediction formula for microcell in 400 MHz to 8GHz band. Electronics Letters 40(11): 685–687