• Title, Summary, Keyword: femtocell

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Femtocell System Technology Analysis (Femtocell 시스템 기술 분석)

  • Jung, Jae-Hwan;Sohn, In-Soo
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.9 no.4
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    • pp.169-173
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    • 2009
  • In the recent, the communication market increased every year. Because of the user's demands and exhaustion of wireless resource, we needs a new technology of the communication system. The femtocell is one of the new technology of the communication system. 'Femto' means very small. By using the femtocell that made up the very small cell, the frequency efficiency increase. The femtocell has different cell environments. In the paper, we look around the femtocell system model, the femtocell system technology and simulation result of system performance.

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Handover Control for WCDMA Femtocell Networks

  • Chowdhury, Mostafa Zaman;Jang, Yeong-Min
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.5B
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    • pp.741-752
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    • 2010
  • The ability to seamlessly switch between the macro networks and femtocell networks is a key driver for femtocell network deployment. The handover procedures for the integrated femtocell/macrocell networks differ from the existing handovers. Some modifications of existing network and protocol architecture for the integration of femtocell networks with the existing macrocell networks are also essential. These modifications change the signal flow for handover procedures due to different 2-tier cell (macrocell and femtocell) environment. The handover between two networks should be performed with minimum signaling. A frequent and unnecessary handover is another problem for hierarchical femtocell/macrocell network environment that must be minimized. This work studies the details mobility management schemes for small and medium scale femtocell network deployment. To do that, firstly we present two different network architectures for small scale and medium scale WCDMA femtocell deployment. The details handover call flow for these two network architectures and CAC scheme to minimize the unnecessary handovers are proposed for the integrated femtocell/macrocell networks. The numerical analysis for the proposed M/M/N/N queuing scheme and the simulation results of the proposed CAC scheme demonstrate the handover call control performances for femtocell environment.

A Power Control Algorithm for Performance Enhancement in Femtocell Systems (펨토셀 시스템 용량 개선을 위한 전력 제어 알고리즘)

  • Jung, Jae-Hwan;Sohn, Insoo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.9
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    • pp.1020-1025
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    • 2016
  • In the recent, the communication market increased every year. Because of the user's demands and exhaustion of wireless resource, we needs a new technology of the communication system. The femtocell is one of the new technology of the communication system. 'Femto' means very small. By using the femtocell that made up the very small cell, the frequency efficiency increase. The femtocell has different cell environments. The Power Control is important for femtocell to avoid interference and unnecessary handover. In this paper, we propose a new femtocell power control that is improvement of handover probability and throughput. And we simulate and check the result.

Dynamic Reservation Scheme of Physical Cell Identity for 3GPP LTE Femtocell Systems

  • Lee, Poong-Up;Jeong, Jang-Keun;Saxena, Navrati;Shin, Ji-Tae
    • Journal of Information Processing Systems
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    • v.5 no.4
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    • pp.207-220
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    • 2009
  • A large number of phone calls and data services will take place in indoor environments. In Long Term Evolution (LTE), femtocell, as a home base station for indoor coverage extension and wideband data service, has recently gained significant interests from operators and consumers. Since femtocell is frequently turned on and off by a personal owner, not by a network operator, one of the key issues is that femtocell should be identified autonomously without system information to support handover from macrocell to femtocell. In this paper, we propose a dynamic reservation scheme of Physical Cell Identities (PCI) for 3GPP LTE femtocell systems. There are several reserving types, and each type reserves a different number of PCIs for femtocell. The transition among the types depends on the deployed number of femtocells, or the number of PCI confusion events. Accordingly, flexible use of PCIs can decrease PCI confusion. This reduces searching time for femtocell, and it is helpful for the quick handover from macrocell to femtocell. Simulation results show that our proposed scheme reduces average delay for identifying detected cells, and increases network capacity within equal delay constraints.

Interference-Aware Downlink Resource Management for OFDMA Femtocell Networks

  • Jung, Hyun-Duk;Lee, Jai-Yong
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.5 no.3
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    • pp.508-522
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    • 2011
  • Femtocell is an economical solution to provide high speed indoor communication instead of the conventional macro-cellular networks. Especially, OFDMA femtocell is considered in the next generation cellular network such as 3GPP LTE and mobile WiMAX system. Although the femtocell has great advantages to accommodate indoor users, interference management problem is a critical issue to operate femtocell network. Existing OFDMA resource management algorithms only consider optimizing system-centric metric, and cannot manage the co-channel interference. Moreover, it is hard to cooperate with other femtocells to control the interference, since the self-configurable characteristics of femtocell. This paper proposes a novel interference-aware resource allocation algorithm for OFDMA femtocell networks. The proposed algorithm allocates resources according to a new objective function which reflects the effect of interference, and the heuristic algorithm is also introduced to reduce the complexity of the original problem. The Monte-Carlo simulation is performed to evaluate the performance of the proposed algorithm compared to the existing solutions.

Femtocell Subband Selection Method for Managing Cross- and Co-tier Interference in a Femtocell Overlaid Cellular Network

  • Kwon, Young Min;Choo, Hyunseung;Lee, Tae-Jin;Chung, Min Young;Kim, Mihui
    • Journal of Information Processing Systems
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    • v.10 no.3
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    • pp.384-394
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    • 2014
  • The femtocell overlaid cellular network (FOCN) has been used to enhance the capacity of existing cellular systems. To obtain the desired system performance, both cross-tier interference and co-tier interference in an FOCN need to be managed. This paper proposes an interference management scheme that adaptively constructs a femtocell cluster, which is a group of femtocell base stations that share the same frequency band. The performance evaluation shows that the proposed scheme can enhance the performance of the macrocell-tier and maintain a greater signal to interference-plus-noise ratio than the outage level can for about 99% of femtocell users.

Spectrum Reuse with Power Control for Two-Tier Femtocell Networks

  • Kim, Youngju;Wang, Hano;Hong, Daesik
    • IEIE Transactions on Smart Processing and Computing
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    • v.3 no.5
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    • pp.275-284
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    • 2014
  • This paper considers two-tier networks consisting of macrocells and femtocells operating in the same spectrum. This paper proposes a femtocell spectrum reuse scheme that determines the shared spectrum and transmit power for the femtocells to mitigate the effects of cross-tier interference between the macrocells and femtocells. The proposed scheme provides macrocell throughput that is unaffected by the increasing number of femtocells per cell site and improves the femtocell signal quality at the same time by limiting the cross-tier interference. This study analyzed the per-tier signal-to-interference ratio (SIR) and outage probability of the proposed scheme to investigate the macrocell and femtocell performance. The total throughput of the proposed scheme was analyzed based on the outage probabilities. The analysis and numerical results proved that high femtocell throughput can be achieved using only a small fraction of the spectrum while protecting the macrocell throughput. As a result, an improved total throughput was achieved enforcing higher spatial reuse.

Interference Avoidance through Pilot-Based Spectrum Sensing Algorithm in Overlaid Femtocell Networks

  • Sambanthan, Padmapriya;Muthu, Tamilarasi
    • ETRI Journal
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    • v.38 no.1
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    • pp.30-40
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    • 2016
  • Co-channel interference between macro-femtocell networks is an unresolved problem, due to the frequency reuse phenomenon. To mitigate such interference, a secondary femtocell must acquire channel-state knowledge about a co-channel macrocell user and accordingly condition the maximum transmit power of femtocell user. This paper proposes a pilot-based spectrum sensing (PSS) algorithm for overlaid femtocell networks to sense the presence of a macrocell user over a channel of interest. The PSS algorithm senses the pilot tones in the received signal through the power level and the correlation metric comparisons between the received signal and the local reference pilots. On ensuring the existence of a co-channel macrocell user, the maximum transmit power of the corresponding femtocell user is optimized so as to avoid interference. Time and frequency offsets are carefully handled in our proposal. Simulation results show that the PSS algorithm outperforms existing sensing techniques, even at poor received signal quality. It requires less sensing time and provides better detection probability over existing techniques.

System Capacity and Coverage Analysis of Hierarchical Femtocell Networks (펨토셀 기반 계층셀 구조 시스템 용량 및 서비스 반경 분석)

  • O, Nam-Geol;Kim, Hoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.6A
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    • pp.476-483
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    • 2009
  • Recently much attention has been devoted to femtocell's potential to improve indoor cellular coverage and high speed wireless communications. Femtocell based commercial services have been already launched in some countries and standardization activities are actively on-going, there has been concern however over potential issues of interference between femtocells and the micro/macro networks. With universal frequency reuse, the ensuing cross-tier interference causes unacceptable data rate and outage probability, so an analysis of effect of interference in femtocell embedded networks would be necessary for a stable system design. This paper investigates the effect of interference on system performances of femtocell embedded hierarchical cell structure (HCS) networks considering the characteristics of propagation environments. Various channel parameters are specially considered for indoor environments where most of femtocells are deployed to investigate the effect of interference of femtocell embedded RCS networks. System capacity and coverage are provided with variant distance between macrocell and femtocell, location of the user in femtocell coverage, and characteristic of building structures.

Constructing femtocell service clusters with improved scalability (확장성을 고려한 안전한 Femtocell 서비스 클러스터 구성 기법)

  • Lee, JongHyup;Seo, SungHoon;Song, JooSeok
    • Proceedings of the Korea Information Processing Society Conference
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    • pp.1126-1127
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    • 2009
  • 이동통신의 급속한 발전과 함께 사용자의 서비스 요구를 만족시키기 위한 femtocell 기술이 개발되고 있다. Femtocell 기지국은 적은 사용자를 대상으로 고품질의 서비스를 제공할 수 있지만, 기존 기지국에 비하여 숫자가 많고 별도의 사용자 접속 리스트를 유지한다는 점에서 확장성 측면에서 한계를 보이고 있다. 따라서, 본 논문에서는 지리적 특성과 사용자 연관성이 높은 femtocell 기지국 간 하나의 관리 영역을 가지기 위한 서비스 클러스터 구성 기법을 제안한다. 제안하는 기법은 femtocell 기지국들과 이동단말들의 상호 작용만을 통하여 수행되므로 높은 확장성을 가진다.

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