@inproceedings{liu_li_yin_dai_2016, title={Connectivity for overlaid wireless networks with outage constraints}, DOI={10.1109/icassp.2016.7472382}, abstractNote={We study the connectivity of overlaid wireless networks where two users can communicate if the signal-to-interference ratio is larger than a threshold subject to an outage constraint. By using percolation theory, we first specify a 2-dimensional connectivity region defined as the set of density pairs-the density of secondary users and the density of primary users- within which the secondary network is percolated. Several interesting properties of this region are also revealed. Our work provides a new perspective for better understanding of the connectivity of large-scale overlaid networks.}, booktitle={International conference on acoustics speech and signal processing}, author={Liu, Y. and Li, C. Z. and Yin, C. C. and Dai, H. Y.}, year={2016}, pages={3771–3775} }
 @inproceedings{liu_li_yin_dai_2015, title={A unified framework for wireless connectivity study subject to general interference attack}, DOI={10.1109/icc.2015.7249471}, abstractNote={Connectivity is crucial to ensure information availability and survivability for wireless networks. In this paper, we propose a unified framework to study the connectivity of wireless networks under a general type of interference attack, which can address diverse applications including Cognitive Radio, Jamming attack and shadowing effect. By considering the primary users, jammers and deep fading as unified Interferers, we investigate a 3-dimensional connectivity region, defined as the set of key system parameters - the density of users, the density of Interferers and the interference range of Interferers - with which the network is connected. Further we study the impact of the Interferers' settings on node isolation probability, which is a fundamental local connectivity metric. Through percolation theory, the sufficient and necessary conditions for global connectivity are also derived. Our study is supported by simulation results.}, booktitle={2015 ieee international conference on communications (icc)}, author={Liu, Y. and Li, C. Z. and Yin, C. C. and Dai, H. Y.}, year={2015}, pages={7174–7179} }
 @article{li_dai_2014, title={Throughput Scaling of Primary and Secondary Ad Hoc Networks With Same-Order Dimensions}, volume={63}, ISSN={["1939-9359"]}, DOI={10.1109/tvt.2014.2310424}, abstractNote={In this paper, the scaling law of the network throughput of a special type of heterogeneous networks is studied, where a secondary network composed of cognitive users shares the same resources opportunistically with a primary network of licensed users. Some pioneering works in this area showed that this type of heterogeneous networks performs as well as two stand-alone networks under the dense network model. A key assumption behind this conclusion is that the density of the secondary network is higher than that of the primary network in the order sense, which essentially decouples the two overlaid networks as the secondary network dominates asymptotically. In this paper, we endeavor to investigate this problem with a weaker condition that the dimensions of the two overlaid networks are on the same order, under the extended network model. Our analysis shows that, with the ratio of the two network sizes larger than a threshold, this weaker (and arguably more practical) condition does not degrade either network throughput scaling. Our result further reveals the potential of cognitive radio (CR) technology in real applications.}, number={8}, journal={IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY}, author={Li, Chengzhi and Dai, Huaiyu}, year={2014}, month={Oct}, pages={3957–3966} }
 @inproceedings{li_dai_2011, title={On the throughput scaling of cognitive radio ad hoc networks}, DOI={10.1109/infcom.2011.5935063}, abstractNote={Due to the emergence of Cognitive Radio, a special type of heterogeneous networks attracts increasing interest recently, in which a secondary network composed of cognitive users shares the same resources opportunistically with a primary network of licensed users. Network throughput in this setting is of essential importance. Some pioneer works in this area showed that this type of heterogeneous networks performs as well as two stand-alone networks, under the dense network model where the size of a network grows with the node density in a fixed area. A key assumption behind this conclusion is that the density of the secondary network is higher than that of the primary one in the order sense, which essentially decouples the two overlaid networks, as the secondary network dominates asymptotically. In this paper we endeavor to investigate this problem with a weaker condition that the dimensions of the two overlaid networks are on the same order, and consider the extended network model where the size of a network scales with the area with the node density fixed. Surprisingly, our analysis shows that this weaker (and arguably more practical) condition does not degrade either network throughput in terms of scaling law. Our result further reveals the potentials of CR technology in real applications.}, booktitle={2011 proceedings ieee infocom}, author={Li, C. Z. and Dai, H. Y.}, year={2011}, pages={241–245} }
 @inproceedings{li_dai_2011, title={Transport throughput of secondary networks in spectrum sharing systems}, DOI={10.1109/infcom.2011.5935105}, abstractNote={Spectrum sharing systems such as cognitive radio networks have drawn much attention recently due to their potential to resolve the conflict between increasing demand for spectrum and spectrum shortage. Such systems are typically composed of primary and secondary networks; the configuration of the latter depends on spectrum opportunity unexploited in the former. In this paper we explore the characteristics of the single hop transport throughput (STT) of the secondary network with outage constraints imposed on both networks. STT is a new metric that inherits the merits of both the traditional transport capacity and another popular metric, transmission capacity, incorporating transmission distance and outage probability into a uniform framework. We first derive the limit of STT, single hop transport capacity (STC), together with a practical upper bound for it. Then we investigate STT with secondary receivers randomly located in the field of interest. Three models regarding the selection of receivers are considered: optimally selected, randomly selected, or the nearest. Study on these models provides a comprehensive view of achievable secondary network throughput, and offers insights into the configuration of secondary networks. In addition, the broadcast transport throughput (BTT) of the secondary networks is also investigated as an extension of STT, and its similarity with STT in the nearest neighbor model is revealed.}, booktitle={2011 proceedings ieee infocom}, author={Li, C. Z. and Dai, H. Y.}, year={2011}, pages={2732–2740} }
 @article{li_dai_li_2010, title={Collaborative Quickest Spectrum Sensing via Random Broadcast in Cognitive Radio Systems}, volume={9}, ISSN={["1558-2248"]}, DOI={10.1109/twc.2010.07.091667}, abstractNote={Quickest detection is applied in spectrum sensing in cognitive radio systems when multiple secondary users collaborate with limited communication time slots. When the transmissions of sensing results are not coordinated to avoid confliction, random broadcast is used to exchange information. A necessary condition for the optimal broadcast probability, as a function of the log likelihood ratio of local observation, is obtained using variational analysis. To alleviate the difficulty of computing the optimal broadcast probability, a simple threshold broadcast scheme is proposed. Simulation shows that the proposed threshold broadcast scheme can achieve substantial performance gain (less than 60% in detection delay for the same false alarm rate) over schemes of random broadcast without regulation and single-user spectrum sensing.}, number={7}, journal={IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS}, author={Li, Husheng and Dai, Huaiyu and Li, Chengzhi}, year={2010}, month={Jul}, pages={2338–2348} }
 @article{li_dai_2010, title={Transport Capacity and Connectivity of Cognitive Radio Networks with Outage Constraint}, DOI={10.1109/isit.2010.5513267}, abstractNote={In this paper we study two basic properties, capacity and connectivity, of Cognitive Radio networks. Our goal is to quantitatively characterize the relationship and tradeoff among key system parameters involved in these properties, incorporating channel randomness and interference into the performance analysis. In particular, we explore the characterization of a capacity metric, single-hop transport capacity, with respect to arbitrarily and randomly located receivers, and investigate a fundamental connectivity metric, node isolation probability. The tradeoff between capacity and connectivity is also revealed.}, journal={2010 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY}, author={Li, Chengzhi and Dai, Huaiyu}, year={2010}, pages={1743–1747} }
 @inproceedings{li_dai_li_2009, title={adaptive quickest change detection with unknown parameter}, DOI={10.1109/icassp.2009.4960315}, abstractNote={Quickest detection of an abrupt distribution change with an unknown time varying parameter is considered. A novel adaptive approach is proposed to tackle this problem, which is shown to outperform the celebrated Parallel CUSUM Test. Performance is evaluated through theoretical analysis and numerical simulations.}, booktitle={International conference on acoustics speech and signal processing}, author={Li, C. Z. and Dai, H. Y. and Li, H. S.}, year={2009}, pages={3241–3244} }