On The Combined Effect Of Directional Antennas And Imperfect Spectrum Sensing Upon Ergodic Capacity Of Cognitive Radio Systems

Abstract

We consider a cognitive radio system, consisting of a primary transmitter (PUtx), a primary receiver (PUrx), a secondary transmitter (SUtx), and a secondary receiver (SUrx). The secondary users (SUs) are equipped with steerable directional antennas. We assume the SUs and primary users (PUs) coexist. We find the ergodic capacity of channel between SUtx and SUrx, and study how spectrum sensing errors affect the capacity. In our system, the SUtx first senses the spectrum and then transmits data at two power levels, according to the result of sensing. The optimal SUtx transmit power levels and the optimal directions of SUtx transmit antenna and SUrx receive antenna are obtained by maximizing the ergodic capacity, subject to average transmit power and average interference power constraints. To study the effect of fading channel, we considered three scenarios: 1) when SUtx knows fading channels between SUtx and PUrx, PUtx and SUrx, SUtx and SUrx, 2) when SUtx knows only the channel between SUtx and SUrx, and statistics of the other two channels, and, 3) when SUtx only knows the statistics of these three fading channels. For each scenario, we explore the optimal SUtx transmit power levels and the optimal directions of SUtx and SUrx antennas.

Publication Date

4-10-2018

Publication Title

Conference Record of 51st Asilomar Conference on Signals, Systems and Computers, ACSSC 2017

Volume

2017-October

Number of Pages

1702-1706

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

DOI Link

https://doi.org/10.1109/ACSSC.2017.8335650

Socpus ID

85050974904 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85050974904

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