@article {23519,
	title = {Performance Analysis of Cognitive Relay Networks Over Nakagami-m Fading Channels},
	journal = {IEEE Journal on Selected Areas in Communications (IEEE JSAC)},
	volume = {33},
	year = {2015},
	month = {05/2015},
	pages = {865-877},
	publisher = {IEEE},
	author = {Zhang, X. and Zhang, Yan and Yan, Z. and Xiang, Jie and Wang, W.}
}
@article {23511,
	title = {Performance Analysis of Cognitive Relay Networks Over Nakagami-m Fading Channels},
	journal = {IEEE Journal on Selected Areas in Communications (IEEE JSAC)},
	volume = {33},
	year = {2015},
	month = {05/2015},
	pages = {865-877},
	publisher = {IEEE},
	author = {Zhang, X. and Zhang, Yan and Xiang, Jie and Wang, W.}
}
@inproceedings {24521,
	title = {Hybrid Spectrum Sharing in Cognitive Two-Way Relay Networks},
	journal = {WPMC 2014 (Best Paper Award)},
	year = {2014},
	author = {Zhang, X. and Zhang, Yan and Zhang, Z. and Xiang, Jie and Wang, W.}
}
@article {Simula.simula.2434,
	title = {The Nornet Edge Platform for Mobile Broadband Measurements},
	journal = {Computer Networks},
	number = {61},
	year = {2014},
	abstract = {We present Nornet Edge (NNE), a dedicated infrastructure for measurements and experimentation in mobile broadband networks. NNE is unprecedented in size, consisting of more than 400 measurement nodes geographically distributed all over Norway. Each measurement node is a Linux-based embedded computer, and is connected to multiple mobile broadband providers. In addition, NNE includes an extensive backend system for deploying and managing experiments and collecting data. NNE makes it possible to run long-term measurement experiments to assess and compare quality and performance across different network operators on a national scale. Particular focus is put on allowing experiments to run in parallel on multiple network connections, and on collecting rich context information related to the experiments. In this paper we give a detailed presentation of NNE, and describe three different measurement experiments that illustrate how the infrastructure can be used. We also provide a roadmap for further development of NNE.},
	keywords = {Conference, Internal Seminar, University of Oslo, Workshop},
	doi = {10.1016/j.bbr.2011.03.031},
	author = {Kvalbein, Amund and Baltrunas, D{\v z}iugas and Evensen, Kristian and Xiang, Jie and Elmokashfi, Ahmed and Ferlin, Simone}
}
@inproceedings {Simula.simula.1116,
	title = {Characterizing Delays in Norwegian 3G Networks},
	journal = {Proceedings PAM 2012},
	volume = {7192},
	year = {2012},
	publisher = {Springer},
	type = {Conference},
	abstract = {This paper presents a first look at long-term delay measurements from data connections in 3 Norwegian 3G Networks. We have performed active measurements for more than 6 months from 90 voting locations used in a trial with electronic voting during this fall{\textquoteright}s regional elections. Our monitors are geographically spread across all of Norway, and give an unprecedented view of the performance and stability of the total 3G infrastructure of a country. In this paper, we focus on delay characteristics. We find large differences in delay between different monitors. More interestingly, we observe that the delay characteristics of the different operators are very different, pointing to operator-specific network design and configurations as the most important factor for delays.},
	author = {Elmokashfi, Ahmed and Kvalbein, Amund and Xiang, Jie and Evensen, Kristian},
	editor = {Riciatto, Fabio and Taft, Nina}
}
@phdthesis {Simula.simula.756,
	title = {Resource Management and Optimization for Cognitive Radio Networks},
	year = {2011},
	month = {December},
	school = {University of Oslo},
	type = {phd},
	author = {Xiang, Jie}
}
@inproceedings {Simula.win.4,
	title = {Admission and Power Control for Cognitive Radio Cellular Networks: a Multidimensional Knapsack Solution},
	journal = {CogART 2010, invited paper},
	year = {2010},
	month = {November},
	publisher = {IEEE},
	type = {Workshop},
	abstract = {Admission and power control schemes play important roles in deploying cognitive radio technology to cellular networks. In this paper, we propose a method to calculate the power scale factor, introduce two pre-admission control schemes, and reformulate the problem as a multidimensional knapsack problem. In addition, we propose a novel admission and power control scheme called JAPC-MKP. Simulation results show that our proposed JAPC-MKP can very closely approach the optimal results from the optimization software MOSEK, and greatly outperform the existing schemes in most cases.},
	isbn = {978-1-4244-8132-3},
	author = {Xiang, Jie and Zhang, Yan and Skeie, Tor},
	editor = {De Sanctis, Mauro}
}
@inproceedings {Simula.simula.524,
	title = {Delay Reduction for Real Time Services in IEEE 802.22 Wireless Regional Area Network},
	journal = {The 21st Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC 2010)},
	year = {2010},
	month = {September 2010},
	pages = {1836-1841},
	publisher = {IEEE},
	type = {Conference},
	abstract = {Real time traffic such as voice and video have strict requirements on the acceptable end-to-end packet delay. When there are different types of traffic with different requirements on tolerable latency, priority based packet scheduling schemes are normally used in order to reduce the queuing delay for real time services. However, in cognitive radio networks, the time that the system spends on spectrum sensing adds further delay to the packet transmission. In this paper, we propose a new scheme to significantly reduce the overall packet delay, including the delay due to sensing for real time services in cognitive radio networks. We derive the expression for average packet delay for the proposed scheme and the simulation results match well with the analytical results. The numerical results show that the priority based scheduling scheme combined with our scheme substantially reduces the packet delay for real time applications.},
	isbn = {978-1-4244-8017-3},
	doi = {10.1109/PIMRC.2010.5671631},
	author = {Maharjan, Sabita and Xiang, Jie and Zhang, Yan and Gjessing, Stein},
	editor = {IEEE, }
}
@article {Simula.win.6,
	title = {Downlink Spectrum Sharing for Cognitive Radio Femtocell Networks},
	journal = {IEEE Systems Journal},
	volume = {4},
	number = {4},
	year = {2010},
	note = {Special issue on Broadband Access Networks},
	month = {December},
	pages = {524-534},
	abstract = {Femtocell is envisioned as a highly promising solution for indoor wireless communications. The spectrum allocated to femtocells is traditionally from the same licensed spectrum bands of macrocells. In this case, the capacity of femtocell networks is highly limited due to the finite number of licensed spectrum bands and also the interference with macrocells and other femtocells. In this paper, we propose a radically new communication paradigm by incorporating cognitive radio in femtocell networks. The cognitive radio enabled femtocells are able to access spectrum bands not only from macrocells but also from other licensed systems (e.g. TV systems) provided the interference from femtocells to the existing systems is not harmful. It results in more channel opportunities for femtocells. Thus, the co-channel interference in femtocells can be greatly reduced and the network capacity can be significantly improved. Because of the difference from other traditional wireless networks, we argue the traditional spectrum sharing schemes such as coloring methods are not efficient to femtocell networks especially for dense deployment scenarios. We formulate the downlink spectrum sharing problem in cognitive radio femtocell networks, and employ decomposition theories to solve the problem. Simulation results indicate that cognitive radio enabled femtocells could achieve much higher capacity than the femtocell networks which do not employ agile spectrum access. Simulation results also show that our proposed scheme without any iteration can achieve almost twice of the average capacity by coloring method when the number of available channels is less than five. Moreover, our proposed scheme can converge very fast with a typical value of only five iterations, and it can achieve around two percent extra average capacity than the fixed power control scheme.},
	doi = {10.1109/JSYST.2010.2083230},
	author = {Xiang, Jie and Zhang, Yan and Skeie, Tor and Xie, Lang}
}
@article {Simula.ND.383,
	title = {Medium Access Control Protocols in Cognitive Radio Networks},
	journal = {Wiley Wireless Communications and Mobile Computing},
	volume = {10},
	number = {1},
	year = {2010},
	note = {Special issue on Recent Advances in Wireless Communications and Networks},
	month = {January},
	pages = {31-49},
	abstract = {In cognitive radio (CR) networks, medium access control (MAC) protocols play an important role to exploit the spectrum opportunities, manage the interference to primary users (PUs), and coordinate the spectrum access amongst secondary users (SUs). In this paper, we first introduce the challenges in the design and implementation of CR MAC protocols. Then, we make a comprehensive survey of the state-of-the-art CR MAC protocols and categorize them on the basis of spectrum sharing modes, i.e., overlay and underlay modes. We also introduce some other classification metrics such as architecture (centralized or distributed), sharing behaviors (cooperative or non-cooperative), and access modes (contention based or contention free). Through the study, we find out that most CR MAC protocols are designed for the overlay mode. The CR MAC protocols in underlay mode could yield higher spectrum utilization efficiency with the cost of more complicated power and admission control schemes. The centralized CR MAC protocols are more suitable to do spectrum sensing using quiet period of whole network, while the distributed CR MAC protocols are more flexible to deploy. We identify several future directions, such as more practical CR MAC protocols for underlay mode, MAC protocols considering security, MAC protocols considering heterogeneous coexistence, etc.},
	doi = {10.1002/wcm.906},
	author = {Xiang, Jie and Zhang, Yan and Skeie, Tor}
}
@inproceedings {Simula.netsys.20,
	title = {Reliable Channel Selection and Routing for Real-Time Services Over Cognitive Radio Mesh Networks},
	journal = {Qshine 2010},
	year = {2010},
	publisher = {ACM},
	type = {Conference},
	abstract = {In Cognitive Radio Mesh Networks (CogMesh), Secondary Mesh Routers (SMRs) can opportunistically utilize the licensed spectrums for the traffic of the Secondary Mesh Users (SMUs). How to guarantee Quality of Service (QoS) for real-time services over CogMesh is still an opening issue. In this paper, we present a discrete-time vacation queueing system to abstract the Primary User (PU) interruption to SMR data transmission. Moreover, we formulate the optimization problem of joint channel selection and routing, to achieve minimum end-to-end delay for SMR while guaranteeing the channel unavailability. A heuristic method is proposed to solve this problem and results show our proposed method performs the most close to the optimal scheme, and outperforms the minimal unavailability scheme and minimal delay scheme in terms of end-to-end delay and solution rate.},
	author = {Xie, Lang and Poul E. {Heegaard} and Zhang, Yan and Xiang, Jie},
	editor = {Zhang, Xi}
}
@inproceedings {Simula.win.2,
	title = {System State Aware Admission Control Scheme for IEEE 802.16 WiMAX-Based Healthcare System},
	journal = {Proceedings of the 6th International Wireless Communications and Mobile Computing Conference (IWCMC {\textquoteright}10)},
	year = {2010},
	publisher = {ACM},
	type = {Conference},
	abstract = {Wireless healthcare is an evolutionary concept which is able to provide pervasive healthcare services to anyone, anytime and anywhere. IEEE 802.16e WiMAX, well known as the novel broadband wireless access technology, seems to be a feasible solution to implement wireless healthcare functionalities. In this paper, we consider wireless healthcare scenario using IEEE 802.16e WiMAX systems. After analyzing the characteristics of WiMAX technology and its application in healthcare service, we focus on the Quality of Service (QoS) guaranteeing issues and present a system state aware connection admission control scheme. In the proposed scheme, the resource utilization is modeled as a finite state machine (FSM) with three states and different admission control strategies is adopted adaptively. Our aim is to achieve a trade-off between satisfying Quality of Service (QoS), fairness and system bandwidth load. Simulation results are presented to demonstrate the performance of the proposed scheme.},
	isbn = {978-1-4503-0062-9},
	doi = {10.1145/1815396.1815608},
	author = {Xie, Lang and Poul E. {Heegaard} and Zhang, Jin and Xiang, Jie},
	editor = {Helmy, Ahmed and Mueller, Peter}
}
@inproceedings {Simula.ND.405,
	title = {Dynamic Spectrum Sharing in Cognitive Radio Femtocell Networks},
	journal = {2009 Fourth International Conference on Access Networks (ACCESSNETS 2009), invited paper},
	volume = {37},
	year = {2009},
	month = {November},
	pages = {164-178},
	publisher = {Springer},
	type = {Conference},
	abstract = {Femtocell is envisioned as a highly promising solution to tackle the communications in the indoor environments, which has been a very challenging problem for mobile network operators. Currently, the spectrum allocated to femtocells is from the same licensed spectrum of macrocells, and the same mobile network operator. In this case, the capacity of femtocell networks may be largely limited due to the finite number of licensed spectrum bands and also the interference with other femtocells and macrocells. In this paper, we propose a radically new communications paradigm by incorporating cognitive radio in femtocell networks (COGFEM). In COGFEM, the cognitive radio enabled femtocells are able to access licensed spectrum bands not only from macrocells but also from other licensed systems (e.g. TV systems). Thus, the co-channel interference in femtocells can be greatly reduced and the network capacity can be significantly improved. We formulate a joint channel allocation and power control problem in COGFEM, and present two intelligent algorithms for efficient spectrum sharing in COGFEM. Results indicate that COGFEM is able to achieve much higher capacity than the femtocell networks which does not employ agile spectrum access.},
	isbn = {978-3-642-11663-6},
	author = {Xiang, Jie and Zhang, Yan and Skeie, Tor},
	editor = {Xiao Jun {Hei} and Cheung, Lawrence}
}
@inproceedings {Simula.ND.253,
	title = {Joint Bandwidth Reservation and Admission Control in IEEE 802.16e Based Networks},
	journal = {the IEEE International Conference on Communications (ICC 2009)},
	year = {2009},
	month = {June},
	pages = {1-6},
	publisher = {IEEE},
	type = {Conference},
	abstract = {The IEEE 802.16e is a compatible and reasonable technology to solve the last mile access problem. Since the multiple services in the system are connection-oriented, it is crucial to provide effective admission control and resource allocation mechanisms to guarantee the Quality of Service (QoS) of the system. In this paper, we investigate the joint bandwidth reservation and admission control in the IEEE 802.16e networks. Foremost, we consider two system models: model without buffer and model with buffer. Then two optimization problems are formulated for the two models separately. To solve the two min-max optimization problems, we propose a bandwidth reservation algorithm. In addition, the bandwidth reservation thus obtained can be used with admission control jointly. Our aim is to enhance fairness while satisfying QoS requirement. Numerical results are presented to demonstrate the performance of the proposed scheme in terms of maximal call blocking probability and fairness.},
	keywords = {Conference},
	isbn = {978-1-4244-3435-0},
	doi = {10.1109/ICC.2009.5199109},
	author = {Xie, Lang and Xiang, Jie and Zhang, Yan and Zhang, Jin},
	editor = {Akhavan, Hamid}
}
@inproceedings {Simula.ND.349,
	title = {Joint QoS-Aware Admission Control, Channel Assignment, and Power Allocation for Cognitive Radio Cellular Networks},
	journal = {Proceedings of the 6th IEEE International Conference on Mobile Ad-hoc and Sensor Systems (IEEE MASS 2009)},
	year = {2009},
	publisher = {IEEE},
	type = {1},
	isbn = {978-1-4244-5113-5},
	author = {Xin, Qin and Xiang, Jie}
}
@inproceedings {Simula.ND.281,
	title = {Minimum-Latency Gossiping in Multi-Hop Wireless Mesh Networks},
	journal = {Proceedings of the IEEE 44th International Conference on Communications (ICC{\textquoteright}09)},
	year = {2009},
	publisher = {IEEE},
	type = {Conference},
	abstract = {Wireless Mesh Networks (WMNs) is an emerging communication paradigm to enable resilient, cost-efficient and reliable services for the future-generation wireless networks. We study the minimum-latency communication primitive of gossiping (all-to-all communication) in multi-hop ad-hoc WMNs. Each mesh node in the WMN is initially given a message and the objective is to design a minimum-latency schedule such that each mesh node distributes its message to all other mesh nodes. Minimum-latency gossiping problem is known to be NP-hard even for the scenario in which the topology of the WMN is known to all mesh nodes in advance. We show an approximation scheme that can complete gossiping task in O(n{\l}og^{\frac{3}{2}} n) time units with high probability at least 1-\frac{1}{n} in any ad-hoc WMN of size n. Our algorithm allows the labels (identifiers) of the mesh nodes to be polynomially large in n. To the best of our knowledge, this is the first time that randomized algorithm has been considered in ad-hoc WMNs with large labels. Moreover, our gossiping scheme also significantly improved all current gossiping algorithms in terms of approximation ratio. Our work has approximation ratio at most O({\l}og^{\frac{3}{2}} n) which is a great improvement of the current best known state-of-the-art algorithm with approximation ratio O({\l}og^2 n) but for linearly large node labels by Czumaj and Rytter \cite{CR03} [FOCS\&$\#$39;03].},
	isbn = {978-1-4244-3435-0},
	author = {Xin, Qin and Zhang, Yan and Xiang, Jie}
}
@inproceedings {Simula.ND.331,
	title = {Optimal Sensing Cooperation for Spectrum Sharing in Cognitive Radio Networks},
	journal = {European Wireless 2009 (EW 2009)},
	year = {2009},
	month = {May},
	pages = {216-221},
	publisher = {IEEE},
	type = {Conference},
	abstract = {Cognitive radio is a highly promising technology to efficiently solve the spectrum scarcity challenge and harmonize the networks heterogeneity. Through component spectrum sharing, Secondary Users (SUs) are able to opportunistically access licensed spectrum shared with the primary system. In the literature, spectrum sharing is normally investigated on the basis of the assumption that the spectrum sensing is perfect. However, in reality, the spectrum sensing can not be ideal, as demonstrated by two non-zero metrics, probability of misdetection and the probability of false alarm. In this paper, we focus on the interaction between spectrum sensing and spectrum sharing. In particular, we will study the optimization of cooperative spectrum sensing for achieving maximum spectrum utilization in cognitive radio networks. A new percentage rule is proposed for the spectrum sensing cooperation, which is more generic than quantity-based rules and is applicable in both sparse and dense sensing scenarios. An analytical model is presented to analyze the spectrum sharing performance. Numerical examples are presented to show the optimal percentage of cooperating sensors in achieving maximum utilization, which simultaneously achieve minimum blocking probabilities. Results are also shown to explore the impact of key system parameters on the performance metrics.},
	isbn = {978-1-4244-5935-3},
	doi = {10.1109/EW.2009.5357760},
	author = {Zhang, Yan and Xiang, Jie and Xin, Qin and Geir Egil {{\O}ien}},
	editor = {Marcos Katz Frank {Fitzek}}
}
@article {Simula.ND.241,
	title = {Power-Fixed and Power-Aware MAC Protocols for Multi-Hop Wireless Networks With Large Interference Area},
	journal = {IEEE Transactions on Vehicular Technology},
	volume = {58},
	number = {6},
	year = {2009},
	pages = {2966-2976},
	author = {Zhang, Yan and Chen, H. and Xiang, Jie and Guizani, M.}
}
@article {Simula.ND.287,
	title = {QoS Aware Admission and Power Control for Cognitive Radio Cellular Networks},
	journal = {Wiley Wireless Communications and Mobile Computing},
	volume = {9},
	number = {11},
	year = {2009},
	month = {November},
	pages = {1520-1531},
	publisher = {Wiley},
	abstract = {In cognitive radio cellular networks, the Secondary Users (SUs) are allowed to access the channels licensed to the Primary Users (PUs) including Primary Transmitters (PTs) and Primary Receivers (PRs), only if the interference to the PRs is less than the predefined threshold, and the Quality of Service (QoS) requirements of PTs are guaranteed. In addition, different SUs may require different levels of QoS, and pay differently depending on the provided QoS. The network operator achieves different secondary revenues by admitting SUs in different QoS levels. The problem we address in this paper is to maximize the total secondary revenue relative to the interference constraints on PRs, and QoS requirements for both PTs and SUs. We formulate this optimization problem, and propose a power control scheme for both PTs and SUs. Then, we introduce three solutions including an exact solution using dynamic programming, a greedy heuristic algorithm, and a minimal SINR removal algorithm. Based on these algorithms, we propose three QoS aware admission and power control schemes, one optimal solution called QAPC-Dynamic, and two approximate solutions called QAPC-Greedy and QAPC-MSRA, respectively. Numerical results show that QAPC-Dynamic always achieves the highest secondary revenue while QAPC-MSRA gives the lowest secondary revenue. Since the time complexity of QAPC-Dynamic is much higher than the other two schemes, QAPC-Greedy is recommended considering the trade-off between the computation complexity and performance gain.},
	doi = {10.1002/wcm.765},
	author = {Xiang, Jie and Zhang, Yan and Skeie, Tor and He, Jianhua}
}
@inproceedings {Simula.ND.197,
	title = {Joint Admission and Power Control for Cognitive Radio Cellular Networks},
	journal = {the 11th IEEE International Conference on Communication Systems 2008 (ICCS 2008), invited paper},
	year = {2008},
	month = {November},
	pages = {1519-1523},
	publisher = {IEEE},
	type = {Conference},
	abstract = {In cognitive radio cellular networks (CogCell), the Secondary Users (SUs) can be admitted to the Base Station (BS) provided that the interference caused by SUs to the Primary Users (PUs) is no higher than the pre-defined threshold. In addition, different SUs may require different Quality of Service (QoS) and hence make different payment based on the provided QoS level. In this paper, we investigate the maximally achievable revenue obtained from SUs subjected to the interference constraints on PUs and QoS requirements of SUs. To solve the identified issue, we introduce the revenue efficiency factor and propose an efficient Joint Admission and Power Control scheme using a Minimal Revenue Efficiency Removal algorithm (JAPC-MRER). With comparison to the other two schemes JAPC-MSRA and JAPC-Random, our strategy is able to achieve much higher revenue with guaranteed interference requirements and QoS demands. In addition, the proposed scheme is evaluated with the effects of the key parameters, i.e. the number of PUs, the number of SUs and the interference threshold.},
	isbn = {978-1-4244-2423-8},
	doi = {10.1109/ICCS.2008.4737437},
	author = {Xiang, Jie and Zhang, Yan and Skeie, Tor},
	editor = {Gang Wei Lawren {Wong}}
}
@inproceedings {Simula.ND.149,
	title = {A Novel Bandwidth Degradation Scheme for Admission Control in IEEE 802.16e Networks},
	journal = {the 4th IEEE International Conference on Wireless Communications, Networking and Mobile Computing (WiCOM 2008)},
	year = {2008},
	pages = {1-4},
	publisher = {IEEE},
	type = {Conference},
	abstract = {IEEE 802.16e networks can be widely applied in broadband wireless access scenarios. Admission control is an essential mechanism in IEEE 802.16e networks to guarantee the QoS of different subscribers. In this paper, we propose a novel bandwidth degradation scheme for the admission control in IEEE 802.16e networks. Simulation results are presented to demonstrate the performance of the proposed scheme in terms of service flow blocking rate and system bandwidth utilization.},
	isbn = {978-1-4244-2107-7},
	doi = {10.1109/WiCom.2008.18},
	author = {Xie, Lang and Xiang, Jie},
	editor = {Cuthbert, L.}
}
@inproceedings {Simula.ND.123,
	title = {Optimal Spectrum Scheduling in Cognitive Wireless Mesh Networks},
	journal = {Proceedings of International Wireless Communications and Mobile Computing Conference 2008 (IWCMC{\textquoteright}08)},
	year = {2008},
	pages = {724-728},
	publisher = {IEEE press},
	type = {Conference},
	abstract = {In a Cognitive Wireless Mesh Network (CogMesh), each Cognitive Radio (CR) enabled mesh node can sense and opportunistically access the under-utilized spectrums in the primary system. Since the unoccupied spectrum is location-dependent and time-dependent, the available spectrums in each mesh node are different. With this spectrum heterogeneity, each node shall have the knowledge of spectrum, scheduling, and routing path of other nodes such that it cacommunicate with them with minimal cost and no collision. The problem may occur in a number of the situations, e.g. the routing table re-building and the unicast real-time applications. In this paper, we focus on the 2-hop spectrum scheduling, which will enable any pair of 2-hop neighborhood nodes know the spectrum, collision-free scheduling, and minimal-cost routing path. Two optimal strategies are proposed to address the spectrum scheduling: Optimal Deterministic Spectrum Scheduling (ODS) and Optimal Randomized Spectrum Scheduling (ORS). In the deterministic situation, with the scheme ODS, the 2-hop spectrum scheduling can be solved in polynomial time. In the randomized situation, with the scheme ORS, the 2-hop spectrum scheduling can be solved in polynomial time with high probability at least (1-\frac{1}{n}) where n denotes the network size. The simulation experiment is carried out to show the achievable performance of the proposed algorithms.},
	isbn = {978-1-4244-2202-9},
	author = {Xin, Qin and Zhang, Yan and Xiang, Jie},
	editor = {Chen, Hsiao-Hwa and Zhang, Xi and Guizani, Mohsen and Athanasios V. {Vasilakos}}
}
@inproceedings {Simula.ND.147,
	title = {QoS-Aware Channel Selection in Cognitive Radio Networks: a Game-Theoretic Approach},
	journal = {IEEE Global Communications Conference (GLOBECOM 2008)},
	year = {2008},
	pages = {1-7},
	publisher = {IEEE},
	type = {Conference},
	abstract = {Abstract-In a cognitive radio wireless network, each node can sense and opportunistically access the under-utilized spectrums in the primary system. Since the unoccupied spectrum is locationdependent and time-dependent, the available spectrums in each node are different.With this spectrum heterogeneity and different Quality-of-Service (QoS) requirement, different node may have different preference in using a particular channel to communicate with its neighboring nodes. In this paper, we formulate this channel selection problem using a cooperative game theoretical approach such that the QoS requirement of each node is guaranteed and the total throughput is maximized. To further improve the performance, a learning negotiation mechanism is introduced. The key motivation is to derive new mixed strategies of the nodes with the reference to the historical profiles of all selected strategies in the past. Simulation results are presented to show the fast convergence of the game, the high efficiency of the learning mechanism, and the effect of mobility.},
	isbn = {978-1-4244-2324-8},
	doi = {10.1109/GLOCOM.2008.ECP.934},
	author = {Hai Ngoc {Pham} and Xiang, Jie and Zhang, Yan and Skeie, Tor},
	editor = {Richard W. {Miller}}
}
@inproceedings {Simula.ND.145,
	title = {Revenue-Based Admission Control for Cognitive Radio Cellular Systems},
	journal = {2008 International Workshop on Cognitive Networks and Communications (COGCOM 2008), in conjunction with CHINACOM 2008},
	year = {2008},
	publisher = {IEEE VTS},
	type = {Workshop},
	isbn = {978-1-4244-2373-6},
	author = {Xie, Lang and Xiang, Jie and Zhang, Yan},
	editor = {IEEE, }
}
@inproceedings {Simula.ND.68,
	title = {Ad Hoc Network State Aware Routing Protocol},
	journal = {2007 IEEE Wireless Communications and Networking Conference (WCNC 2007)},
	year = {2007},
	month = {March},
	pages = {3746-3751},
	publisher = {IEEE Communications Society},
	type = {Conference},
	abstract = {The environment of a mobile ad hoc network may vary greatly depending on nodes{\textquoteright} mobility, traffic load and resource conditions. In this paper we categorize the environment of an ad hoc network into three main states: an ideal state, wherein the network is relatively stable with sufficient resources; a congested state, wherein some nodes, regions or the network is experiencing congestion; and an energy critical state, wherein the energy capacity of nodes in the network is critically low. Each of these states requires unique routing schemes, but existing ad hoc routing protocols are only effective in one of these states. This implies that when the network enters into any other states, these protocols run into a sub optimal mode, degrading the performance of the network. We propose an ad hoc network state aware routing protocol (ANSAR) which conditionally switches between earliest arrival scheme and a joint load-energy aware scheme depending on the current state of the network. Comparing to existing schemes, it yields higher efficiency and reliability as shown in our simulation results.},
	isbn = {1-4244-0659-5},
	author = {Xiang, Jie and Sesay, Samba and Wang, Yiming and He, Jianhua},
	editor = {Ben Letaief, Khaled}
}
@inproceedings {Simula.ND.48,
	title = {Ad Hoc Network State Aware Routing Protocol},
	journal = {the 2007 IEEE Wireless Communications and Networking Conference (WCNC 2007)},
	year = {2007},
	pages = {3746-3751},
	publisher = {IEEE},
	type = {Conference},
	abstract = {The environment of a mobile ad hoc network may vary greatly depending on nodes{\textquoteright} mobility, traffic load and resource conditions. In this paper we category the environment of ad hoc network into three main states: an ideal state, wherein the network is relatively stable with sufficient resources; a congested state, wherein some nodes, regions or the network is experiencing congestion; and an energy critical state, wherein the energy capacity of nodes in the network is critically low. Each of these states requires unique routing schemes, but existing ad hoc routing protocols are only effective in one of these states. This implies that when the network enters into any other states, these protocols run into a sub optimal mode, degrading the performance of the network. We propose an Ad hoc Network State Aware Routing Protocol (ANSAR) which conditionally switch between earliest arrival scheme and a joint Load-Energy aware scheme depending on the current state of the network. Comparing to existing schemes, it yields higher efficiency and reliability as shown in our simulation results.},
	isbn = {1-4244-0658-7},
	author = {Xiang, Jie and Sesay, Samba and Wang, Yiming and He, Jianhua},
	editor = {Ben Letaief, Khaled}
}
@inproceedings {Simula.ND.67,
	title = {A New Adaptive Energy Management Scheme in IEEE 802.16e Mobile WiMAX},
	journal = {Norwegian Informatics Conference 2007 (NIK 2007)},
	year = {2007},
	pages = {111-114},
	publisher = {Tapir Akademisk Forlag},
	type = {Conference},
	isbn = {978-82-519-2272-2},
	author = {Zhang, Yan and Xiang, Jie},
	editor = {Frode Eika {Sandnes}}
}
@inproceedings {Simula.ND.153,
	title = {Hotspot Mitigation With Measured Node Throughput in Mobile Ad Hoc Networks},
	journal = {the 6th International Conference on ITS Telecommunications (ITST 2006)},
	year = {2006},
	month = {June},
	pages = {749-752},
	publisher = {IEEE},
	type = {Conference},
	abstract = {A network node or region is said to be experiencing hotspot when it is subjected to a traffic load substantially larger than the design load, creating a situation wherein demand for network resources exceeds that available for use. Due to the dynamics and lack of central control in mobile ad hoc wireless network (MANET), it is common to have imbalance in the distribution of network traffic load. This issue compounded by the utilization of shortest path route selection metrics makes hotspot intrinsic to MANET. Under hotspot conditions a network would experience high contention and congestion that may in turn result in increased packet loss, end-to-end delay, transmission errors and faster battery power depletion. This phenomenon generally degrades the overall performance of the network. At a node, hotspot can be detected through high buffer occupancy, packet loss, and excessive MAC contention delay. No single one of these metrics alone can accurately detect hotspot. Monitoring these parameters independently and combining them to accurately detect hotspot would result in a complex scheme. In this paper, we are proposing a simple and effective hotspot mitigation scheme {\textquoteright}HUNT{\textquoteright} based on the throughput of network nodes. Through simulation experimentation, we prove that HUNT can effectively mitigate hotspot in best effort on-demand routing protocols such as DSR and yields improved efficiency, reliability and robustness.},
	isbn = {0-7803-9587-5},
	author = {Sesay, Samba and Xiang, Jie and He, Jianhua and Yang, Zongkai and Cheng, Wenqing},
	editor = {Li, Lemin}
}
@inproceedings {Simula.ND.157,
	title = {Ensuring Efficiency and Robustness in MANET},
	journal = {the 2nd International Conference on Mobile Technology, Applications and Systems (Mobility 2005)},
	year = {2005},
	month = {November},
	pages = {152-157},
	publisher = {IEE},
	type = {Conference},
	abstract = {This paper introduces a joint load balancing and hotspot mitigation protocol for Mobile Ad-hoc Network (MANET) termed by us as "Load Energy Balance + Hotspot Mitigation protocol (LEB+HM)". We argue that although Ad-hoc Wireless Networks have limited network resources - Bandwidth and Power, prone to frequent link/node failures and have high security risk; existing ad hoc routing protocols do not put emphasis on maintaining robust link/node, efficient use of network resources and on maintaining the security of the network. Typical route selection metrics used by existing ad hoc routing protocols are shortest hop, shortest delay, and loop avoidance. These routing philosophy have the tendency to cause traffic concentration on certain regions or nodes, leading to heavy contention, congestion and resource exhaustion which in turn may result in increased end-to-end delay, packet loss and faster battery power depletion, degrading the overall performance of the network. Also in most existing on-demand ad hoc routing protocols intermediate nodes are allowed to send route reply RREP to source in response to a route request RREQ. In such situation a malicious node can send a false optimal route to the source so that data packets sent will be directed to or through it, and tamper with them as wish. It is therefore desirable to adopt routing schemes which can dynamically disperse traffic load, able to detect and remove any possible bottlenecks and provide some form of security to the network. In this paper we propose a combine Adaptive load energy balancing and hotspot mitigation scheme that aims at evenly distributing network traffic load and energy, mitigate against any possible occurrence of hotspot and provide some form of security to the network. This combine approach is expected to yield high reliability, availability and robustness, that best suits any dynamic and scalable ad hoc network environment. Dynamic Source Routing (DSR) was use as our underlying protocol for the implementation of our algorithm. Simulation comparison of our protocol to that of original DSR shows that our protocol has reduced node/link failure, even distribution of battery energy, and better network service efficiency.},
	isbn = {981-05-4573-8},
	author = {Sesay, Samba and Yang, Zongkai and He, Jianhua and Xiang, Jie and Du, Xu},
	editor = {Boo, Ivan}
}
@inproceedings {Simula.ND.155,
	title = {A Packet Loss Salvation Scheme for Voice Over MANET},
	journal = {the 2nd International Conference on Mobile Technology, Applications and Systems (Mobility 2005)},
	year = {2005},
	month = {November},
	pages = {311-316},
	publisher = {IEE},
	type = {Conference},
	abstract = {This paper experiments a hybrid of Mobile ad hoc wireless network (MANET) and fixed land network. We analyze the issues of transferring voice over such networks, and provide a packet loss salvation scheme to reduce packet loss rate. We also provide a new estimation mechanism by utilizing information gleaned from the upstream intermediate node. We take jitter into consideration and analyze how jitter exerts its influence. According to this packet transmission metrics decisions could be made on whether or not a packet should be transmitted at a particular time. Our protocol algorithm was implemented on Ad hoc On-demand Distance Vector (AODV) routing protocol. From our simulation results and analysis it is shown that our scheme can reduce packet loss rate in voice over MANET compared to that of the original AODV.},
	isbn = {981-05-4573-8},
	author = {Xie, Nan and Xiang, Jie and He, Jianhua and Sesay, Samba},
	editor = {Boo, Ivan}
}
@inproceedings {Simula.ND.69,
	title = {Subjective Quality Evaluation for Voice Over MANET},
	journal = {the 2005 International Conference on Wireless Communications, Networking and Mobile Computing(WCNM 2005)},
	volume = {2},
	year = {2005},
	month = {September},
	pages = {1112-1115},
	publisher = {IEEE},
	type = {Conference},
	abstract = {Due to the dynamic and multihop nature of the mobile ad-hoc network (MANET), voice communication over MANET may encounter many challenges. We set up a subjective quality evaluation model using ITU-T E-model with extension. And through simulation in NS-2, we evaluate how the following factors impact voice quality in MANET: the number of hops, the number of route breakages, the number of communication pairs and the background traffic. Using AODV as the underlying routing protocol, and with the MAC layer changed from 802.11 DCF to 802.11e EDCF, we observe that 802.11e is more suitable for implementing voice communication over MANET.},
	isbn = {0-7803-9335-X},
	author = {Xiang, Jie and He, Jianhua and Sesay, Samba and Xie, Nan},
	editor = {Zhou, Huaibei}
}
