Location-Aware Spectrum and Power Allocation in Joint Cognitive Communication-Radar Networks Yogesh Nijsure and Yifan Chen Newcastle University Newcastle upon Tine, UK Email: {y.nijsure;yifan.chen2}@ncl.ac.uk Chau Yuen Singapore University of Technology and Design, Singapore Email: yuenchau@sutd.edu.sg Yong Huat Chew Institute for Infocomm Research Singapore Email: chewyh@i2r.a-star.edu.sg Abstract—A novel approach to spectrum and power allocation is proposed for joint cognitive communication-radar networks, which aim at integrating cognitive radio (CR-o) and cognitive radar (CR-r) paradigms to achieve intelligent utilization of spec- trum resources in wireless networks. This approach exploits the location information offered by CR-r combined with spectrum sensing capability of CR-o to aid spectrum and power allocation by minimizing harmful interference among neighboring devices. Such systems require both coexistence and sharing of perception of radio environment and radar scene. To offer better spectrum resource utilization, entropy of the received signal is employed in order to detect spectrum holes over the network topology. This entropy-based technique also demonstrates superior performance as compared to the conventional method based on energy detec- tion. Simulation results indicate both throughput improvement and interference reduction among neighboring devices. I. I NTRODUCTION Dynamic spectrum access allows frequency bands to be as- signed based on the needs of radios without causing significant interference and degradation to the overall throughput. The concept of system cognition proves to be an effective way for intelligent spectrum management in wireless networks [1], [2]. The design and implementation of cognitive radios (CR- o) that constantly adapt their operational modes according to the changing radio environment are therefore necessary to utilize the spectrum more efficiently [3]. In terms of CR-o, primary users (PUs) of spectrum resources are referred to as the authorized users of the radio channels and secondary users (SUs) compete for the channels when PUs are inactive [1], [2]. Hence, one of the most important challenges of CR-o is spectrum hole detection, which is to acquire awareness of the frequency usage and existence of PUs in neighboring bands. On the other hand, when SUs are using the vacant channels, CR-o can also be aware of initialization of any primary communication activities in their vicinity. The detection of PUs is very important, not only to prevent interference but also to detect any opportunity of communication for SUs as shown in [1]. Location information of CR-o can prove to be beneficial in identifying spectrum holes over the network, which can be used to assist in spectrum allocation in order to avoid inter- ference among users in close vicinity. This information can be obtained from a dedicated cognitive radar (CR-r) network as discussed in [4], [5]. This motivates the design of a novel cognitive radio radar (CRR) system presented in the current work. Essentially, we combine the functionalities of CR-o and CR-r to facilitate localization as well as intelligent spectrum and power allocation. Specifically, in a CRR network, radar targets are also radio users, which results in coexistence of ra- dio environment and radar scene. Furthermore, the knowledge about the location and identification of a specific radar target, which uses certain radio channels for communications, can be fed into the CR-o network to assist in decision making about spectrum assignment strategies. Similarly, the CR-o network can also localize and identify the radio users by analyzing the received signal. This information can be fed into the CR- r network to assist in radar waveform design and selection, target state estimation, and power allocation [4]–[7]. This leads to sharing of perception of radio and radar scenes under surveillance. The key contributions of this paper are: 1) Development of an algorithm based upon entropy of the received signal for spectrum sensing; 2) Integration of CR-o and CR-r concepts to form a CRR network, which achieves location-aware spectrum and power management; and 3) Evaluation of the system throughput and comparison of the proposed method with the conventional energy-based detection in terms of true positive rates. The rest of the paper is organized as follows. In Section II, we describe the proposed CRR network architecture and the entropy-based spectrum sensing. In Section III, we describe the algorithm for spectrum and power allocation among the CR-o users. In Section IV, we present the simulation results on the system throughput and also comparison with the conventional detection technique based on the received signal energy. Finally, some concluding remarks are drawn in Section V. II. CRR NETWORK ARCHITECTURE AND ENTROPY-BASED SPECTRUM SENSING The spectrum mask defined by IEEE 802.11b requires that the signal is attenuated by at least 30 dB from its peak energy at ±11 MHz from the center frequency, and attenuated by at least 50 dB from its peak energy at ±22 MHz from the center frequency [2]. Since the spectrum mask only defines power output restrictions up to ±22 MHz from the center frequency, CROWNCOM 2011, June 01-03, Osaka, Japan Copyright © 2012 ICST DOI 10.4108/icst.crowncom.2011.245751