Polygon Approximation Based Cognitive Information Delivery in Geo-location Database Oriented Spectrum Sharing

( Zhiqing Wei ),( Huici Wu ),( Zhiyong Feng ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.6

In geo-location database oriented spectrum sharing system, the entire geographic area is divided into meshes to classify, store and delivery the cognitive information. In this paper, we propose a flexible polygon mesh division scheme to reduce the number of meshes. Hence the cognitive information can be reduced correspondingly. Besides, polygon mesh can approximate the real environment and reduce the error of cognitive information because the edges of polygon are selected along the boundaries of the networks. We have designed the polygon approximation algorithm and have analyzed the relation between the error and the number of polygon`s edges. Finally, the simulation results are provided to verify the algorithm and analysis. The polygon mesh division scheme in this paper provides an efficient approach for cognitive information organization in database oriented spectrum sharing system.

The Asymptotic Throughput and Connectivity of Cognitive Radio Networks with Directional Transmission

Wei, Zhiqing,Feng, Zhiyong,Zhang, Qixun,Li, Wei,Gulliver, T. Aaron The Korea Institute of Information and Commucation 2014 Journal of communications and networks Vol.16 No.2

Throughput scaling laws for two coexisting ad hoc networks with m primary users (PUs) and n secondary users (SUs) randomly distributed in an unit area have been widely studied. Early work showed that the secondary network performs as well as stand-alone networks, namely, the per-node throughput of the secondary networks is ${\Theta}(1/\sqrt{n{\log}n})$. In this paper, we show that by exploiting directional spectrum opportunities in secondary network, the throughput of secondary network can be improved. If the beamwidth of secondary transmitter (TX)'s main lobe is ${\delta}=o(1/{\log}n)$, SUs can achieve a per-node throughput of ${\Theta}(1/\sqrt{n{\log}n})$ for directional transmission and omni reception (DTOR), which is ${\Theta}({\log}n)$ times higher than the throughput with-out directional transmission. On the contrary, if ${\delta}={\omega}(1/{\log}n)$, the throughput gain of SUs is $2{\pi}/{\delta}$ for DTOR compared with the throughput without directional antennas. Similarly, we have derived the throughput for other cases of directional transmission. The connectivity is another critical metric to evaluate the performance of random ad hoc networks. The relation between the number of SUs n and the number of PUs m is assumed to be $n=m^{\beta}$. We show that with the HDP-VDP routing scheme, which is widely employed in the analysis of throughput scaling laws of ad hoc networks, the connectivity of a single SU can be guaranteed when ${\beta}$ > 1, and the connectivity of a single secondary path can be guaranteed when ${\beta}$ > 2. While circumventing routing can improve the connectivity of cognitive radio ad hoc network, we verify that the connectivity of a single SU as well as a single secondary path can be guaranteed when ${\beta}$ > 1. Thus, to achieve the connectivity of secondary networks, the density of SUs should be (asymptotically) bigger than that of PUs.

The Asymptotic Throughput and Connectivity of Cognitive Radio Networks with Directional Transmission

Zhiqing Wei,Zhiyong Feng,Qixun Zhang,Wei Li,T. Aaron Gulliver 한국통신학회 2014 Journal of communications and networks Vol.16 No.2

Throughput scaling laws for two coexisting ad hoc networkswith m primary users (PUs) and n secondary users (SUs)randomly distributed in an unit area have been widely studied. Early work showed that the secondary network performs as wellas stand-alone networks, namely, the per-node throughput of thesecondary networks is (1/pn log n). In this paper, we showthat by exploiting directional spectrum opportunities in secondarynetwork, the throughput of secondary network can be improved. If the beamwidth of secondary transmitter (TX)’s main lobe is= o(1/log n), SUs can achieve a per-node throughput of(1/pn log n) for directional transmission and omni reception(DTOR), which is (log n) times higher than the throughputwithoutdirectional transmission. On the contrary, if = !(1/log n),the throughput gain of SUs is 2 / for DTOR compared with thethroughput without directional antennas. Similarly, we have derivedthe throughput for other cases of directional transmission. The connectivity is another critical metric to evaluate the performanceof random ad hoc networks. The relation between the numberof SUs n and the number of PUs m is assumed to be n = m . We show that with the HDP-VDP routing scheme, which is widelyemployed in the analysis of throughput scaling laws of ad hoc networks,the connectivity of a single SU can be guaranteed when> 1, and the connectivity of a single secondary path can be guaranteedwhen > 2. While circumventing routing can improve theconnectivity of cognitive radio ad hoc network, we verify that theconnectivity of a single SU as well as a single secondary path canbe guaranteed when > 1. Thus, to achieve the connectivity ofsecondary networks, the density of SUs should be (asymptotically)bigger than that of PUs.

Auditory Feature Driven Model Predictive Control for Sound Source Approaching

Zhiqing Wang,Wei Zou,Hongxuan Ma,Chi Zhang,Yuxin Guo,Wei Zhang 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.2

Sound source approaching is a typical task for the robot with auditory sensing. Many existing methods are based on sound source localization (SSL), and utilize the explicit location as the control input. To reduce the localization computation cost and improve the robustness against noise and reverberation, we propose a novel auditory feature driven model predictive control (AFD-MPC) method, which directly uses the auditory feature as the control input. First, a new convolution-ternarization based interaural time difference (CT-ITD) estimation method is proposed, which is more robust to noise and reverberation by eliminating signal spikes and irrelevant components. Second, a new system model is derived and established, which directly links the robot motions and the interaural time difference (ITD) feature. Third, AFD-MPC is realized based on the proposed CT-ITD feature estimation and system model. The states at multiple future time steps are predicted based on the system model, and a control objective function considering both target approaching and motion smoothness is designed. By involving the multi-step future states in the control objective function, the control outcome is more smooth on motion trajectory and more robust to instantaneous interferences. A series of experiments such as static and dynamic sound source approaching are conducted on a mobile robot equipped with a small-sized 6-microphone array to validate the effectiveness of our methods.

Practical Robotic Auditory Perception and Approaching Methods Based on Small-sized Microphone Array

Zhiqing Wang,Wei Zou,Chi Zhang,Zhaobing Kang,Jiagang Zhu 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.5

Robot control based on audition plays an important role in many robot applications, which is generally implemented by three steps: aural features extraction, sound source localization and approaching control strategy. This paper presents a novel and practical auditory perception and control method adoptable to the small-sized microphone array. Firstly, a novel aural feature extraction strategy, namely dynamic signals matching (DSM), is proposed to search for the matching points of the signals with similarity measurement based on gradient and amplitude by dynamic programming. Secondly, a new sound source localization method called steered grid search (SGS) is proposed, which combines the source localization method based on time delay of arrival (TDOA) and spatial search strategy to achieve the robustness and real-time performance. Thirdly, inspired by image-based visual control, the interaction matrix is deduced and applied to transform the spatial information of the sound source into auditory control, based on which a mechanism for robot to approach the sound source is implemented. Finally, we apply our methods to a mobile robot equipped with a small array of six microphones. The experimental results show the feasibility and the suitability of our method under adverse conditions.