• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권7호
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• pp.2668-2717
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• 2021

Demands for high-speed wireless data services grow rapidly. It is a big challenge to increasing the network capacity operating on licensed spectrum resources. Unlicensed spectrum cellular networks have been proposed as a solution in response to severe spectrum shortage. Licensed Assisted Access (LAA) was standardized by 3GPP, aiming to deliver data services through unlicensed 5 GHz spectrum. Furthermore, the 3GPP proposed 5G New Radio-Unlicensed (NR-U) study item. On the other hand, artificial intelligence (AI) has attracted enormous attention to implement 5G and beyond systems, which is known as Intelligent Radio (IR). To tackle the challenges of unlicensed spectrum networks in 4G/5G/B5G systems, a lot of works have been done, focusing on using Machine Learning (ML) to support resource allocation in LTE-LAA/NR-U and Wi-Fi coexistence environments. Generally speaking, ML techniques are used in IR based on statistical models established for solving specific optimization problems. In this paper, we aim to conduct a comprehensive survey on the recent research efforts related to unlicensed cellular networks and IR technologies, which work jointly to implement 5G and beyond wireless networks. Furthermore, we introduce a positioning assisted LTE-LAA system based on the difference in received signal strength (DRSS) to allocate resources among UEs. We will also discuss some open issues and challenges for future research on the IR applications in unlicensed cellular networks.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2005년도 추계학술대회 및 정기총회
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• pp.321-333
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• 2005

With the limited frequency spectrum and an increasing demand for cellular communication services, the problem of channel assignment becomes increasingly important. However, finding a conflict free channel assignment with the minimum channel span is NP hard. As demand for services has expanded in the cellular segment, sever innovations have been made in order to increase the utilization of bandwidth. The innovations are cellular concept, dynamic channel assignment and hierarchical network design. Hierarchical network design holds the public eye because of increasing demand and quality of service to mobile users. We consider the frequency assignment problem and the base station placement simultaneously. Our model takes the candidate locations emanating from this process and the cost of assigning a frequency, operating and maintaining equipment as an input. In addition, we know the avenue and demand as an assumption. We propose the network about the profit maximization. This study can apply to GSM(Global System for Mobile Communication) which has 70% portion in the world. Hierarchical network design using GA(Genetic Algorithm) is the first three-tier (Macro, Micro, Pico) model, We increase the reality through applying to EMC (Electromagnetic Compatibility Constraints). Computational experiments on 72 problem instances which have 15${\sim}$40 candidate locations demonstrate the computational viability of our procedure. The result of experiments increases the reality and covers more than 90% of the demand.

• 전자공학회논문지S
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• 제35S권3호
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• pp.65-75
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• 1998

We consider connection-oriented wireless cellular networks such as the second generation wireless cellular networks and wirelss ATM networks. In these networks, a separate forward signaling channel is provided for the transmission of paging and channel allocation packets. When a call destined to a user is requested, all the base stations in the user's current location area broadcast the corresponding paging packet across forward signaling channels. By slot mode operation and paging group allocation for fusers in a location area, we can reduce relative power consumption level at battery-operated terminals. However, a sthe number of paging groups is increased for lowering relative power consumption level, a paging packet experiences higher delay to access the forward signaling channel. For the pre-negotiated quality-of-service level, paging packet delay level must be limited. In this paper, we consider static and dynamic multiplexing schemes for paging packets, and develop an analytical method for calculating paging packet delay and relative power consumption levels. Using this analytial method, we investigate the effect of network parameters on the paging packet delay and relative power consumption levels.

• 한국통신학회논문지
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• 제28권10B호
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• pp.845-853
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• 2003

무선 LAN은 유선 LAN 대체의 한계를 넘어 셀룰라 이동 통신망과의 밀결합된 통합이 이루어질 것으로 기대된다. 이러한 통합환경에서 셀룰라 이동 통신망과 무선 LAN과의 상호 핸드오프가 필수적이다. 본 논문에서는 무선 LAN과 셀룰러 시스템과의 vertical 핸드오프 기능 구현에 필요한 요구 사항 및 핸드오프 절차를 제시하였다. 본 논문에서 제안한 vertical 핸드오프 절차는 실제로 vertical 핸드오프를 구현하는데 기초 자료로 활용될 수 있을 것으로 보인다.

• 디지털산업정보학회논문지
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• 제5권3호
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• pp.117-126
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• 2009

Wireless mesh networks (WMNs) consist of mesh routers and mesh clients, where mesh routers have minimal mobility and form the backbone of WMNs. They provide network access for both mesh and conventional clients. The integration of WMNs with other networks such as the Internet, cellular, IEEE 802.11, IEEE 802.15, IEEE 802.16, sensor networks, etc., This paper presents a secure and efficient authentication mechanism for Wireless mesh network. The validity of proposed mechanism is provided by BAN logic and the efficiency of suggested mechanism is showed through the performance evaluation.

• 한국멀티미디어학회논문지
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• 제19권8호
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• pp.1415-1423
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• 2016

Interference in device-to-device (D2D) communication underlaying cellular network needs to be elaborately investigated because of channel sharing. The objective is to improve the quality of D2D communications while maintaining high performance for cellular users. In this paper, we solve the above problem by jointly considering channel allocation and power control using coalition formation game. Our cooperative game theoric approach allows to enhance network-wide performance. We design a merge-and-split algorithm to deal with the complexity of the combinatorial structure in coalition formation problem. The analytical and numerical results show that our algorithm converges to a stable point which achieves high network performance.

• 한국IT서비스학회지
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• 제11권1호
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• pp.239-246
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• 2012

The user increases around the WiBro and in which the mobile broad band service is the wireless internet base technology HSDPA, that is the cellular phone foundation technique, and moreover the issue about the user effective quality guarantee emerges but the quality control of the wireless network is the incomplete actual condition. Therefore, the reliability verification according to the development of the system for the performance measure for the continued wireless data service and it and evaluation are needed for the quality control. In this paper, the wireless data service quality measurement system was implemented with the design. The same test environment as the existing network performance measurement program was built for the reliability verification of the embodied device for measuring quality and evaluation and the cost performance was performed. It could confirm that design and embodied wireless data service quality measurement system operated accurately in this paper through the quality measure result value analysis.

• 정보처리학회논문지C
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• 제13C권2호
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• pp.171-176
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• 2006

최근 무선통신 기술의 비약적인 발전과 함께, 이동 셀룰러 네트워크 상에서 다양한 형태의 멀티미디어 서비스에 대한 수요가 폭발적으로 증가하고 있다. 그러나, 무선 네트워크의 특성상 유선 네트워크에 비해 상대적으로 제한된 대역폭을 가지기 때문에 효율적인 대역폭 관리가 중요한 이슈이다. 본 논문에서는 이동 셀룰러 네트워크상에서의 멀티미디어 서비스를 효율적으로 지원할 수 있는 적응적 온라인 대역폭 관리 알고리즘을 제안하였다. 이 기법은 현재 네트워크의 트래픽 상황을 기반으로 하여 실시간으로 시스템을 관리하여 우선순위가 높은 서비스의 QoS 보장과 동시에 효율적인 대역폭 사용률을 제공한다. 컴퓨터 시뮬레이션을 통하여 대역폭 관리를 위해 제안된 기존의 타 기법들과의 비교, 분석을 수행하여 제안된 방법이 다앙한 네트워크 트래픽 상황에서 우수한 성능을 가지는 것을 확인할 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권2호
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• pp.462-483
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• 2016

The research on optimization of cellular network's energy efficiency (EE) towards environmental and economic sustainability has attracted increasing attention recently. In this survey, we discuss the opportunities, trends and challenges of this challenging topic. Two major contributions are presented namely 1) survey of proposed energy efficiency metrics; 2) survey of proposed energy efficient solutions. We provide a broad overview of the state of-the-art energy efficient methods covering base station (BS) hardware design, network planning and deployment, and network management and operation stages. In order to further understand how EE is assessed and improved through the heterogeneous network (HetNet), BS's energy-awareness and several typical HetNet deployment scenarios such as macrocell-microcell and macrocell-picocell are presented. The analysis of different HetNet deployment scenarios gives insights towards a successful deployment of energy efficient cellular networks.

• 한국전자통신학회논문지
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• 제3권3호
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• pp.188-194
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• 2008

병원 무선망에서 호 수락 방식과 보다 적은 범위 셀 환경에서 QoS를 보장하기 위해 통합된 페이징과 루프 정보 관리 캐시를 사용하는 Cellular IP 특성을 가진 Cellular-IP/PRC 네트워크를 제안한다. 제안한 호 수락 방식은, 이동 노드의 홈 기지국 용량이 충분하고, 인접 셀 이동 노드가 홈 기지국에서 호가 수락되었다고 가정할 경우 받을 간섭의 증가량을 고려해 통화 품질이 보장될 때, 홈 기지국은 새로운 호를 이동 노드의 송신 전력 예측에 기반을 둔 호 수락 방식이다. 병원 무선망 내의 페이징과 라우터를 관리하기 위해 사용되었던 PC(Paging Cache)와 RC(Routing Cache)를 하나의 PRC(Paging Router Cache)로 통합 관리하고, 모든 노드 내에 구성하여 운용토록 하고, 이동 노드의 핸드오프 및 로밍 상태를 효율적으로 관리 할 수 있도록 이동 노드에 핸드오프 상태 머신을 추가하며, 노드에서 관련 기능을 수행하도록 연구한다. 시스템 환경에서 통화량에 영향을 주는 인자를 분석하고 각 링크 통화권 및 불균형 정도를 예측하여, 하향링크에 의해 통화권이 제한되었는지를 판단하여 호를 수락 또는 차단하는 알고리즘 이용 총 송수신 전력을 기반으로 제안한 알고리즘을 응용해서 QoS에서 가장 밀접하고 중요한 호 차단 확률과 호 탈락 확률, GoS(Grade of Service), 셀 용량의 효율을 예측 처리하여 QoS 성능 개선을 나타낸다.