• Journal of Communications and Networks
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• v.13 no.6
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• pp.639-654
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• 2011

In this paper, we present a channel access mechanism, referred to as the enhanced mesh coordinated channel access (eMCCA) mechanism, for IEEE 802.11s-based wireless mesh networks. The current draft of IEEE 802.11s includes an optional medium access control (MAC), denoted as MCCA, which is designed to provide collision-free and guaranteed channel access during reserved periods. However, the MCCA mechanism fails to achieve the desired goal in the presence of contending non-MCCA nodes; this is because non-MCCA nodes are not aware of MCCA reservations and have equal access opportunities during reserved periods. We first present a probabilistic analysis that reveals the extent to which the performance of MCCA may be affected by contending non-MCCA nodes. We then propose eMCCA, which allows MCCA-enabled nodes to enjoy collision-free and guaranteed channel access during reserved periods by means of prioritized and preemptive access mechanisms. Finally, we evaluate the performance of eMCCA through extensive simulations under different network scenarios. The simulation results indicate that eMCCA outperforms other mechanisms in terms of success rate, network throughput, end-to-end delay, packet-loss rate, and mesh coordinated channel access opportunity-utilization.

• Journal of Korea Multimedia Society
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• v.10 no.12
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• pp.1612-1621
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• 2007

In this paper, we introduced our designed TDMA (Time Division Multiple Access) based MAC (Medium Access Control) protocol for Home Networks called HomeTDMA. We have implemented and tested it in a test bed using crossbow motes and TinyOS. We also have compared HomeTDMA and CSMA (Carrier Sense Multiple Access) in terms of space and time complexity, channel access time, delivery success ratio, and throughput. Based on our results, HomeTDMA has an advantage over CSMA on channel access time, throughput and delivery success ratioIn the case of complexity, HomeTDMA is more complex compared to CSMA. Thus, CSMA is more appropriate in wireless sensor networks (WSNs) where memory, energy, and throughput are important parameters to be considered. However, HomeTDMA has a natural advantage of collision free medium access and is very promising for home networks where a reliable transmission or data transfer and congestion control is highly preferred.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2150-2162
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• 2012

In accordance with evolution of next-generation mobile Internet, 2G, 3G, 4G, and B4G mobile communication wireless access networks will be co-existed and service providers will be merged as an integrated service provider. In addition, multiple virtual service operators will appear. In order to provide complicated unified-services, in the future Internet, wireless network virtualization where network resource is shared by various service operators is necessary. Therefore, in this paper, we investigate network architectures and virtualization scenarios for wireless access network virtualization where various wireless access technologies are flexibly operated by multiple service providers over next-generation wireless access networks. We expect that the virtualization scenario and network architecture yielded from this study can play a role as a basis for development of wireless access network virtualization algorithms.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.4
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• pp.216-222
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• 2009

This paper proposes an integrated mobile sink networks management system which can monitor and control various kinds of wireless lan access points, located in many different areas divided by their managing groups, from multi-vendors, and their operations in networks. The proposed system has the center-local interoperability structure cooperating with local-center servers which can perform the same operations as the central servers for wireless lan access points from multi-vendors and wireless lan centric management features. For this purpose, we propose a new way of data design, messaging policy, and hierarchical system structure such that we can achieve stable and consistent management methods for various wireless access points on distributed networks.

• Journal of Communications and Networks
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• v.18 no.2
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• pp.135-149
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• 2016

Cloud radio access network (C-RAN) refers to the virtualization of base station functionalities by means of cloud computing. This results in a novel cellular architecture in which low-cost wireless access points, known as radio units or remote radio heads, are centrally managed by a reconfigurable centralized "cloud", or central, unit. C-RAN allows operators to reduce the capital and operating expenses needed to deploy and maintain dense heterogeneous networks. This critical advantage, along with spectral efficiency, statistical multiplexing and load balancing gains, make C-RAN well positioned to be one of the key technologies in the development of 5G systems. In this paper, a succinct overview is presented regarding the state of the art on the research on C-RAN with emphasis on fronthaul compression, baseband processing, medium access control, resource allocation, system-level considerations and standardization efforts.

• Journal of Internet Computing and Services
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• v.18 no.2
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• pp.1-11
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• 2017

There are two kinds of wireless network access to a certain place by using smart devices - 1) open (anonymous) - access and 2) user-authorized access. The open-access is a non-authorization connection method which does not need to require Smart device's user authorized information. It means open-access use only user's SSID (Service Set Identifier) information to access the wireless AP devices following public wireless network standard. This access mechanism is not suitable to use all of public wireless networks because users have to get all wireless network information around them. As a result, huge data for smart devices should be one of the most critical overload problems for them. Secondly, the user-authorized access method uses wireless network information (SSID and password) chosen by the users. So, the users have to remember and use the network access information data manually whenever accessing the network. Like open-access, this access method also has the operational and inconvenient problem for the users - manually inputting access information whenever connecting to the network. To overcome this problem in both schemes, we propose two improved wireless network access methods: 1) the implementation of automatic AP connection mechanism using user-authorization and iBeacon messages, and 2) SSID registration form for public wireless networks.

• ETRI Journal
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• v.31 no.1
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• pp.83-85
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• 2009

Compared with unicast, multicast over wireless ad-hoc networks do not support reliability due to their inability to exchange request-to-send/clear-to-send (RTS/CTS) and ACK packets with multiple recipients. Although several media access control (MAC) layer protocols have been proposed to provide reliable multicast, these introduce additional overhead, which degrades system performance. A novel MAC protocol for reliable wireless multicast is proposed in this paper. By adapting orthogonal frequency division multiple access characteristics in CTS and ACK packets, the protocol achieves reliability over wireless multicast with minimized overhead.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.3131-3149
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• 2016

In-band Full-duplex (IBFD) wireless communication allows improved throughput for wireless networks. The current Half-duplex (HD) medium access mechanism Request to Send/Clear to Send (RTS/CTS) has been directly applied to IBFD wireless networks. However, this is only able to support a symmetric dual link, and does not provide the full advantages of IBFD. To increase network throughput in a superior way to the HD mechanism, a novel three-way handshaking access mechanism RTS/SRTS (Second Request to Send)/CTS is proposed for point to multipoint (PMP) IBFD wireless networks, which can support both symmetric dual link and asymmetric dual link communication. In this approach, IBFD wireless communication only requires one channel access for two-way simultaneous packet transmissions. We first describe the RTS/SRTS/CTS mechanism and the symmetric/asymmetric dual link transmission procedure and then provide a theoretical analysis of network throughput and delay using a Markov model. Using simulations, we demonstrate that the RTS/SRTS/CTS access mechanism shows improved performance relative to that of the RTS/CTS HD access mechanism.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4293-4304
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• 2014

In order to ensure the wireless connectivity and seamless service to mobile users, the next generation network system will be an integration of multiple wireless access networks. In a heterogeneous wireless access system, bandwidth allocation becomes crucial for load balancing to avoid network congestion and improve system utilization efficiency. In this article, we propose a new dynamic bandwidth allocation scheme for hierarchical wireless network systems. First, we derive a multi-objective decision criterion for each access point. Second, a bargaining strategy selection algorithm is developed for the dynamic bandwidth re-allocation. Based on the intervenient Stackelberg game model, the proposed scheme effectively formulates the competitive interaction situation between several access points. The system performance of proposed scheme is evaluated by using extensive simulations. With a simulation study, it is confirmed that the proposed scheme can achieve better performance than other existing schemes under widely diverse network environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.5
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• pp.1973-1991
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• 2018

Multimedia applications over wireless networks have been evolving to augmented reality or virtual reality services. However, a rich data size compared to conventional multimedia services causes bandwidth bottlenecks over wireless networks, which is one of the main reasons why those applications are not used widely. To overcome this limitation, bandwidth aggregation techniques, which exploit a multi-path transmission, have been considered to maximize link utilization. Currently, most of the conventional researches have been focusing on the user end problems to improve the quality of service (QoS) through optimal load distribution. In this paper, we address the joint pricing and load distribution problem for multi-homing in heterogeneous wireless access networks (ANs), considering the interests of both the users and the service providers. Specifically, we consider profit from resource allocation and cost of power consumption expenditure for operation as an utility of each service provider. Here, users decide how much to request the resource and how to split the resource over heterogeneous wireless ANs to minimize their cost while supporting the required QoS. Then, service providers compete with each other by setting the price to maximize their utilities over user reactions. We study the behaviors of users and service providers by analyzing their hierarchical decision-making process as a multileader-, multifollower Stackelberg game. We show that both the user and service provider strategies are closed form solutions. Finally, we discuss how the proposed scheme is well converged to equilibrium points.