• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권9호
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• pp.4166-4182
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• 2018

We consider the Device-to-Device (D2D) communications in cellular networks where each cellular user (CU) shares the same resource with multiple D2D users (DUs). In this paper, we aim to maximize the energy efficiency (EE) of the D2D networks, subject to an interference constraint required by the CU. Since the cellular and D2D communications belong to different networks, we consider to incentivize base station (BS) while assisting the DUs. To this end, we propose a Stackelberg game based interference pricing framework for the considered D2D communications in cellular networks. Unlike most of the existing methods, we use interference pricing framework to jointly address the EE resource allocation problem and the interference management in our networks rather than only improve the EE of the DUs or protect cellular networks. In particular, BS and all the users do not need all channel state information, which is more realistic in practice. In addition, two different pricing strategies are also proposed. Based on the two strategies, we analyze the equilibrium of the game. Moreover, in the first strategy, the upper and lower boundaries of the interference price are obtained. The closed-form expression is gained with a backward induction for the second strategy. Both offer valuable insights to the considered scenarios. Finally, compared with the existing work, the EE of the D2D communications is significantly improved. The advantageous performance of our scheme are demonstrated by the simulation results.

• 한국정보통신학회논문지
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• 제19권1호
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• pp.91-96
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• 2015

이종의 셀룰러 망은 다양한 무선 환경에서의 이동 단말 서비스를 지원한다. 최근 셀룰러 망에서는 음성 서비스 및 데이터 서비스의 요구가 폭발적으로 증가하고 있는 추세로 기술적 기반이 LTE-A (Long-Term Evolution Advanced)와 IEEE 802.16m 무선망으로 전환되어 보다 많은 수의 기지국 서비스 지원을 필요로 하게 되었다. 셀룰러 망에서의 전력 수요는 대부분 기지국에서 소모되며 이에 기지국의 에너지 소모의 절감이 요구되고 있는 시점이다. 본 논문에서는 동적인 전력 관리 방안을 기반으로 기지국의 전력 소비를 줄이는 방안을 제안한다. 본 논문에서는 시뮬레이션을 통하여 저전력 기지국 수행을 위한 핸드오버 방식의 성능 분석을 수행한다.

• 대한수학회지
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• 제43권2호
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• pp.445-459
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• 2006

In this paper cellular neural networks with continuously distributed delays are considered. Sufficient conditions for the existence and exponential stability of the almost periodic solutions are established by using fixed point theorem, Lyapunov functional method and differential inequality technique. The results of this paper are new and they complement previously known results.

• 대한수학회지
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• 제44권4호
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• pp.873-887
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• 2007

In this paper cellular neutral networks with time-varying delays and continuously distributed delays are considered. Without assuming the global Lipschitz conditions of activation functions, some sufficient conditions for the existence and exponential stability of the almost periodic solutions are established by using the fixed point theorem and differential inequality techniques. The results of this paper are new and complement previously known results.

• Korean Journal of Mathematics
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• 제30권3호
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• pp.491-502
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• 2022

In this paper we investigate some sufficient conditions to guarantee the existence and uniqueness of Stepanov-like weighted pseudo almost periodic solutions of cellular neural networks on Clifford algebra for non-automomous cellular neural networks with multi-proportional delays. Our analysis is based on the differential inequality techniques and the Banach contraction mapping principle.

• 한국통신학회논문지
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• 제28권6A호
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• pp.351-360
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• 2003

무선 이동 네트워크 환경에서 양질의 멀티미디어 서비스를 제공하기 위해서는 트래픽에 대한 QoS가 보장되어야 한다. 그러나 기존의 자원 예약 기법은 유선 네트워크를 위해 설계된 것이므로 무선 이동 네트워크에서의 QoS보장 문제를 상당부분 해결하지 못하고 있다. 또한 최근에는 마이크로 셀들로 구성된 네트워크가 증가함에 따라 빈번한 핸드오프로 인한 전송지연 문제와 MN(Mobile Node)의 위치 이동을 신속하게 제어해야 하는 문제 등이 발생하고 있다. RSVP와 Mobile IP간의 상호 운용을 지원하는 기존 기법들은 매크로 셀 환경을 위해 고안되었으므로 마이크로 셀 환경에서 그대로 사용될 경우 한계점을 갖고 있다. 본 논문에서는 마이크로 셀룰러 네트워크에서 QoS를 보장하기 위해 CRSVP(Cellular RSVP Protocol)를 제안한다.

• Journal of Communications and Networks
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• 제2권1호
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• pp.46-57
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• 2000

Ongoing standardization effort on 3G cellular system in 3GPP (UNTS) is based on GPRS core network and promises a global standard for systems capable of offering ubiquitous access to internet for mobile users. Considered radio access systems(FDD CDMA, TDD CDMA, and EDGE) are optimized for robust mobile use. However, there are alternative relatively high-rate radio interfaces being standardized for WLAN (IEEE802.11 and HIPER-LAN/2) which are capable of delivering significantly higher data rates to static or semi-static terminals with much less overhead. Also WPANs(BLUETOOTH, IEEE802.15), which will be present in virtually every mobile handset in the near future, are offering low cast and considerable access data rate and thus are very attractive for interworking scenarios. The prospect of using these interfaces as alternative RANs inthe modular UMTS architecture is very promising. Additionally, the recent inclusion of M-IP in the UMTS R99 standard opens the way for IP-level interfacing to the core network. This article offers an overview into WLAN-Cellular interworking. A brief overview of GPRS, UMTS cellular architectures and relevant WLAN standards is given. Possible interworking architectures are presented.

• Journal of Communications and Networks
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• 제7권2호
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• pp.192-206
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• 2005

Integration of mobile networks and Internet has started with 2.5 generation of mobile cellular networks. Internet traffic is today dominant traffic type worldwide. The hanger for higher data rates needed for data traffic and new IP based services is essential in the development of future wireless networks. In such situation, even 3G with up to 2 Mbit/s has not provided data rates that are used by Internet users with fixed broadband dial-up or through wired local area networks. The solution to provide higher bit rates in wireless access network has been found in wireless LAN although initially it has been developed to extend wired LAN into wireless domain. In this paper, we propose and describe a solution created for interoperability between mobile cellular network and WLAN. The integration between two networks, cellular and WLAN, is performed on the authentication, authorization, and accounting, i.e., AAA side. For that purpose we developed WLAN access controller and WLAN AAA gateway, which provide gateway-type access control as well as charging and billing functionalities for the WLAN service. In the development process of these elements, we have considered current development stadium of all needed network entities and protocols. The provided solution provides cost-effective and easy-to-deploy PLMN-WLAN Internetworking scenario.

• 한국멀티미디어학회논문지
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• 제18권12호
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• pp.1468-1474
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• 2015

Efficient spectrum sharing is an important issue in Device-to-Device (D2D) communications underlaying cellular networks as it can mitigate the interference to cellular users and improve the performance of the systems. In this paper, we formulate the radio resource allocation in D2D communications as a mixed nonlinear integer programing. We show the formulated problem is NP-hard and thus a polynomial time algorithm to solve is not possible. Since such a problem is very hard to obtain the optimal solution within a short running time, we instead propose a fast heuristic suboptimal algorithm to mitigate the interference caused to cellular users and improve the performance of the systems. Simulation results are provided to evaluate the performance of the proposed algorithm.

• 한국멀티미디어학회:학술대회논문집
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• 한국멀티미디어학회 2012년도 춘계학술발표대회논문집
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• pp.158-159
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• 2012

Heterogeneous cellular networks can provide high throughput and coverage compare to conventional networks of only macrocell deployment, however it operates regardless of total power consumption, which is a very important issue of modern cellular networks. We propose a policy that control the on/off state of base stations in heterogeneous networks according daily traffic profile. Under this policy, the total power consumed can be significantly reduced when the traffic is low while preserving QoS requirement.