Results 1 - 10
of
10
Opportunistic spectrum access for mobile cognitive radios
- in Proceedings of IEEE INFOCOM
, 2011
"... Abstract—Cognitive radios (CRs) can mitigate the impending spectrum scarcity problem by utilizing their capability of ac-cessing licensed spectrum bands opportunistically. While most existing work focuses on enabling such opportunistic spectrum access for stationary CRs, mobility is an important con ..."
Abstract
-
Cited by 9 (0 self)
- Add to MetaCart
(Show Context)
Abstract—Cognitive radios (CRs) can mitigate the impending spectrum scarcity problem by utilizing their capability of ac-cessing licensed spectrum bands opportunistically. While most existing work focuses on enabling such opportunistic spectrum access for stationary CRs, mobility is an important concern to secondary users (SUs) because future mobile devices are expected to incorporate CR functionality. In this paper, we identify and address three fundamental challenges encountered specifically by mobile SUs. First, we model channel availability experienced by a mobile SU as a two-state continuous-time Markov chain (CTMC) and verify its accuracy via in-depth simulation. Then, to protect primary/incumbent communications from SU interference, we introduce guard distance in the space domain and derive the optimal guard distance that maximizes the spatio-temporal spectrum opportunities available to mobile CRs. To facilitate efficient spectrum sharing, we formulate the problem of maximizing secondary network throughput within a convex optimization framework, and derive an optimal, distributed channel selection strategy. Our simulation results show that the proposed spectrum sensing and distributed channel access schemes improve network throughput and fairness significantly, and reduce SU energy consumption for spectrum sensing by up to 74%. I.
Spectrum-Aware Mobility Management in Cognitive Radio Cellular Networks
"... Abstract—Cognitive radio (CR) networks have been proposed as a solution to both spectrum inefficiency and spectrum scarcity problems. However, they face several challenges based on the fluctuating nature of the available spectrum, making it more difficult to support seamless communications, especial ..."
Abstract
-
Cited by 7 (0 self)
- Add to MetaCart
(Show Context)
Abstract—Cognitive radio (CR) networks have been proposed as a solution to both spectrum inefficiency and spectrum scarcity problems. However, they face several challenges based on the fluctuating nature of the available spectrum, making it more difficult to support seamless communications, especially in CR cellular networks. In this paper, a spectrum-aware mobility management scheme is proposed for CR cellular networks. First, a novel network architecture is introduced to mitigate heterogeneous spectrum availability. Based on this architecture, a unified mobility management framework is developed to support diverse mobility events in CR networks, which consists of spectrum mobility management, user mobility management, and intercell resource allocation. The spectrum mobility management scheme determines a target cell and spectrum band for CR users adaptively dependent on time-varying spectrum opportunities, leading to increase in cell capacity. In the user mobility management scheme, a mobile user selects a proper handoff mechanism so as to minimize a switching latency at the cell boundary by considering spatially heterogeneous spectrum availability. Intercell resource allocation helps to improve the performance of both mobility management schemes by efficiently sharing spectrum resources with multiple cells. Simulation results show that the proposed method can achieve better performance than conventional handoff schemes in terms of both cell capacity as well as mobility support in communications. Index Terms—Cognitive radio, spectrum pool, handoff, intercell resource allocation, spectrum mobility management, user mobility management. Ç 1
Random access wireless networks with controlled mobility
- In Proc. IFIP MEDHOCNET’09
, 2009
"... Abstract—This paper considers wireless networks where messages arriving randomly (in time and space) are collected by a mobile receiver. The messages are transmitted to the mobile receiver according to a random access scheme and the receiver dynamically adjusts its position in order to receive these ..."
Abstract
-
Cited by 5 (3 self)
- Add to MetaCart
Abstract—This paper considers wireless networks where messages arriving randomly (in time and space) are collected by a mobile receiver. The messages are transmitted to the mobile receiver according to a random access scheme and the receiver dynamically adjusts its position in order to receive these messages in minimum time. We investigate the use of wireless transmission and controlled mobility to improve the delay performance in such systems. In particular, we characterize the tradeoff between wireless transmission and physical movement of the mobile receiver. We derive a lower bound for the delay in the system and show how it is affected by different communication parameters. We show that the combination of mobility and wireless transmission results in a significant improvement in delay as compared to a system where wireless transmission is not used. I.
Modeling and Analytical Study of Link Properties in Multihop Wireless Networks
"... Abstract—The radio link between a pair of wireless nodes is determined by radio channels, transmission range, node mobility and node-pair distance, which form a set of random factors in multihop wireless networks. The properties of such radio links can be characterized by link lifetime, residual lin ..."
Abstract
-
Cited by 3 (1 self)
- Add to MetaCart
(Show Context)
Abstract—The radio link between a pair of wireless nodes is determined by radio channels, transmission range, node mobility and node-pair distance, which form a set of random factors in multihop wireless networks. The properties of such radio links can be characterized by link lifetime, residual link lifetime and link change rate, which, in fact, have been widely used for network design and performance evaluation. In this paper, we take a new modeling approach that captures the dynamics of radio channels and node movements in small-scale. More specifically, distance transition probability matrix is designed in order to describe the joint effects of dynamic transmission range due to radio channel fading and relative distance of a node-pair resulting from random movements. We find that the PDF of link lifetime can be approximated by an exponential distribution with parameter characterized by the ratio of average node speed ¯ to effective transmission range
Efficient Self-optimization of Neighbour Cell Lists in Macrocellular Networks
, 2011
"... Abstract—The neighbour cell list (NCL) in cellular networks has an important impact on the number of dropped calls and is traditionally optimized manually with the help of planning tools. In this paper, a method for automatically optimizing a NCL is presented, which consists of an initialization usi ..."
Abstract
-
Cited by 2 (1 self)
- Add to MetaCart
(Show Context)
Abstract—The neighbour cell list (NCL) in cellular networks has an important impact on the number of dropped calls and is traditionally optimized manually with the help of planning tools. In this paper, a method for automatically optimizing a NCL is presented, which consists of an initialization using a selfconfiguration phase, followed by a self-optimization phase that further refines the NCL based on measurements provided by mobile stations during the network operation. The performance of the proposed methods is evaluated for different user speeds and different NCL sizes. Besides, the convergence speed of the proposed self-optimization method is evaluated. It is shown that when about 6000 measurements are reported by mobile stations, the proposed self-optimization method attains a stable maximum performance about 99 % of success rate. Index Terms—neighbour cell list, self-optimization, selfconfiguration, cellular networks I.
The unheralded power of cloudlet computing in the vicinity of mobile devices
- in IEEE Globecom Workshops (GC Wkshps
, 2013
"... Abstract—With the popularity of smartphones and explosion of mobile applications, mobile devices are becoming the prevalent computing platform for convenient communication and rich entertainment. Because mobile devices still have limited processor power, computing-intensive applications need to be o ..."
Abstract
-
Cited by 2 (1 self)
- Add to MetaCart
(Show Context)
Abstract—With the popularity of smartphones and explosion of mobile applications, mobile devices are becoming the prevalent computing platform for convenient communication and rich entertainment. Because mobile devices still have limited processor power, computing-intensive applications need to be offloaded to either remote clouds or nearby cloudlets for processing. But, remote cloud computing is hindered by the long latency and expensive roaming charges of cellular radio access. Therefore, cloudlet computing becomes appealing to provide instant and low-cost service through resource-rich devices (e.g., desktops) in the vicinity of mobile devices. It is evident that cloudlet computing is challenged by the intermittent connection between cloudlets and mobile devices due to user mobility. The question is how to evaluate the impact of user mobility on cloudlet computing perfor-mance. In this paper, we examine the cloudlet access probability, task success rate, and task execution speed to measure the impact of mobility. We discover that the cloudlet access probability is µTC/(µTI +µTC) determined by mean connection time µTC and mean inter-connection time µTI between the mobile device and the cloudlet. Furthermore, we find that the task success rate and execution speed depend on not only task computation demand and cloudlet computing speed but also cloudlet access probability. Our findings reveal that the ratio µTC/(µTI + µTC) quantifies the impact of node mobility on both cloudlet access probability and cloudlet computing performance. I.
Wireless Link Quality Modelling and Mobility Management for Cellular Networks Reviewers:
, 2012
"... framework of Conventions Industrielles de Formation par la REcherche (CIFRE) ..."
Abstract
- Add to MetaCart
(Show Context)
framework of Conventions Industrielles de Formation par la REcherche (CIFRE)
Wireless Link Quality Modelling and Mobility Management for Cellular Networks
, 2011
"... HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte p ..."
Abstract
- Add to MetaCart
(Show Context)
HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et a ̀ la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Opportunistic Spectrum Access for
, 2016
"... Opportunistic spectrum access for mobile cognitive radios ..."
(Show Context)
