• 한국통신학회논문지
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• 제40권7호
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• pp.1354-1362
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• 2015

5세대 이동통신 시스템은 4세대 LTE 시스템의 용량 대비 1000배의 용량 증대를 목표로 한다. 이를 달성하기 위해 많은 수의 소형셀을 활용하는 heterogeneous network 기술이 차세대 이동통신 기술로 각광받고 있다. 5세대 이동통신 시스템에서는 고정형 기지국과 이동형 기지국이 기하급수적으로 늘어날 것으로 예상되는데, 이러한 기지국을 모두 유선으로 연결하는 것은 비용 측면에서 합리적이지 않고, 이동형 기지국을 지원하기 위해서는 유선으로 백홀 링크를 지원하는 것보다 효율적인 무선 백홀망 시스템의 구축이 필요하다. 본 논문에서는 이러한 배경을 바탕으로 고정 및 이동 액세스 포인트와 무선 백홀 스위치를 기반으로 한 5세대 이동통신 초광역 무선 백홀망 시스템을 제안, 초광역 무선 백홀망의 link budget을 분석하고 대형 어레이 안테나를 활용한 빔 기반 초광역 무선 백홀망 시스템의 성능을 시뮬레이터 분석을 통해 검증을 진행하였다. 초광역 무선 백홀망 link budget 분석을 통해 1 nJ/Gbps의 에너지 효율의 달성 가능성을 확인하고, 전송 시뮬레이터를 통해 무선 백홀 스위치를 중심으로 $10km^2$의 면적에 이동 액세스 포인트가 여러 위치에 존재할 때 사이드로브를 제어함으로써 빔 간 간섭을 줄일 경우 빔 당 1 W의 전송 전력을 통해 평균 주파수 효율을 5 bps/Hz 이상 달성 가능함을 확인하였다.

• 한국통신학회논문지
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• 제37B권11호
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• pp.993-1003
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• 2012

본 논문에서는 무선 이동 단말이 이기종 망의 다중 연결을 통해 높은 대역폭을 이용하고 또한 이기종 망의 동시사용을 통해 손실 패킷을 감소시킬 수 있는 기법을 제안한다. 현재의 이동 단말은 하나의 네트워크를 통해 데이터를 전송한다. 하지만 제안하는 기법은 이동 단말이 WLAN과 3G망 등 다수의 망이 존재하는 환경에서 하나의 망을 사용하는 것이 아니라 이기종의 망의 동시 사용을 통해 대역폭을 넓게 사용한다. 이기종 망을 동시에 사용할 수 있는 지역으로 이동 단말이 이동하게 되면 이를 인지한 이동 단말은 서버에 이기종 무선망 동시사용 허용 요청을 하게 되고, 이를 수신한 서버는 다수의 프로토콜 연결을 통해 데이터를 전송하게 된다. 또한 제안하는 기법은 이동 단말이 다른 네트워크로 이동할 때 기존의 망을 끊지 않기 때문에 핸드오버 구간에서 발생하는 패킷 손실이 감소하게 된다. 제안하는 기법을 네트워크 시뮬레이션(NS-2)을 통해 실험하였고, 처리량이 향상되었음을 확인하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 춘계학술대회
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• pp.288-289
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• 2013

An integrated security mechanism is one of the key challenges in the open wireless network architecture because of the diversity of the wireless network in open wireless network and the unique security mechanism used in each one of these networks. Optimized security protocols and mechanisms are employed for the high performance and security. Finally, a challenge in the near future will converge the integration of Open Ubiquitous Sensor Network (OUSN) with security protocols for applying the their applications. We analysed unique network-centric features and security mechanism of various heterogeneous wireless networks.

• 융합신호처리학회논문지
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• 제13권3호
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• pp.156-161
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• 2012

임의 접속(random access) 프로토콜은 기본적으로 센싱 기능을 가지고 있으며, 이것을 이용하여 분산형 무선 네트워크 시스템 구축에 적합한 특징을 가지고 있다. 이러한 기술적 특징은 중앙식 제어(centralized control)가 어려운 이기종 시스템들이 동작하는 인지 무선 통신 환경에 대하여 장점을 가지며, 인지 무선 통신 환경에서 임의 접속의 성능을 검증해 보아야 한다는 동기를 제공한다. 이 논문에서 우리는 인지 무선 통신 환경에서 CSMA/CA(carrier-sensing multiple access with collision avoidance)기법을 도입하고, 성능을 분석하는 기본 틀을 제공한다.

• ETRI Journal
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• 제41권4호
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• pp.452-464
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• 2019

The use of wireless body area networks (WBANs) in healthcare applications has made it convenient to monitor both health personnel and patient status continuously in real time through wearable wireless sensor nodes. However, the heterogeneous and complex network structure of WBANs has some disadvantages in terms of control and management. The software-defined network (SDN) approach is a promising technology that defines a new design and management approach for network communications. In order to create more flexible and dynamic network structures in WBANs, this study uses the SDN approach. For this, a WBAN architecture based on the SDN approach with a new energy-aware routing algorithm for healthcare architecture is proposed. To develop a more flexible architecture, a controller that manages all HUBs is designed. The proposed architecture is modeled using the Riverbed Modeler software for performance analysis. The simulation results show that the SDN-based structure meets the service quality requirements and shows superior performance in terms of energy consumption, throughput, successful transmission rate, and delay parameters according to the traditional routing approach.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권10호
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• pp.4642-4660
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• 2016

One major concern of applying Multipath TCP (MPTCP) to data delivery in heterogeneous wireless networks is that the utilization of asymmetric paths with diverse networking-related parameters may cause severe packet reordering and receive buffer blocking (RB²LOC). Although many efforts are devoting to addressing MPTCP's packet reordering problems, their sender-controlled solutions do not consider balancing overhead between an MPTCP sender and receiver, and their fully MPTCP mode cannot make MPTCP achieve a desired performance. This paper proposes a novel receiver-centric buffer blocking-aware data scheduling strategy for MPTCP (dubbed MPTCP-rec) necessitating the following aims: (1) alleviating MPTCP's packet reordering and RB²LOC problems, (2) improving the MPTCP performance, and (3) balancing load between the MPTCP sender and receiver. Simulation results show that the proposed MPTCP-rec solution outperforms the existing MPTCP solutions in terms of data delivery performance in heterogeneous wireless networks.

• Journal of Information Processing Systems
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• 제13권3호
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• pp.500-517
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• 2017

In this paper, an improved zone-based routing protocol for heterogeneous wireless sensor networks is proposed. The proposed protocol has fixed the sized zone according to the distance from the base station and used a dynamic clustering technique for advanced nodes to select a cluster head with maximum residual energy to transmit the data. In addition, we select an optimal route with minimum energy consumption for normal nodes and conserve energy by state transition throughout data transmission. Simulation results indicated that the proposed protocol performed better than the other algorithm by reducing energy consumption and providing a longer network lifetime and better throughput of data packets.

• 한국정보기술학회 영문논문지
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• 제8권2호
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• pp.13-25
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• 2018

The paper analyzes the sum spectral efficiency (SE) for a heterogeneous cellular network (HetNet) which has the backhaul, provided with wireless full-duplex massive multiple-input multiple-out (MIMO) with hardware distortions. We derive approximate expressions to obtain the uplink/downlink sum SE of the backhaul. The analytic results have been shown to be exact when compared to Monte Carlo simulations. From the analysis, it is shown that the desired signal and the hardware distortion noise have the same order. The sum SE generally improves when the number of receive antennas increases but degrades when the hardware quality reduces. A sum SE performance ceiling is introduced by the hardware quality level.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.768-771
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• 2006

In WSN(Wireless Sensor Network) environment, a large amount of sensors, which are small and heterogeneous, generates data stream successively in physical space. These sensors are composed of measured data and metadata. Metadata includes various features such as location, sampling time, measurement unit, and their types. Until now, wireless sensors have been managed with individual specification, not the explicit standardization of metadata, so it is difficult to collect and communicate between heterogeneous sensors. To solve this problem, OGC(Open Geospatial Consortium) has proposed a SensorML(Sensor Model Language) which can manage metadata of heterogeneous sensors with unique format. In this paper, we introduce a metadata model using SensorML specification to manage various sensors, which are distributed in a wide scope. In addition, we implement the metadata management module applied to the sensor data stream management system. We provide many functions, namely generating metadata file, registering and storing them according to definition of SensorML.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권3호
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• pp.1336-1356
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• 2017

The spectrum scarcity crisis has resulted in a shortage of resources for many emerging wireless services, and research on dynamic spectrum management has been used to solve this problem. Game theory can allocate resources to users in an economic way through market competition. In this paper, we propose a bidding game-based spectrum allocation mechanism in cognitive radio network. In our framework, primary networks provide heterogeneous wireless service and different numbers of channels, while secondary users have diverse bandwidth demands for transmission. Considering the features of traffic and QoS demands, we design a weighted interference graph-based grouping algorithm to divide users into several groups and construct the non-interference user-set in the first step. In the second step, we propose the dynamic bidding game-based spectrum allocation strategy; we analyze both buyer's and seller's revenue and determine the best allocation strategy. We also prove that our mechanism can achieve balanced pricing schema in competition. Theoretical and simulation results show that our strategy provides a feasible solution to improve spectrum utilization, can maximize overall utility and guarantee users' individual rationality.