• Title/Summary/Keyword: M-WiMAX

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Adjacent Interference Analysis between M-WiMAX OFDMA/TDD and WCDMA FDD System in the 2.6 GHz Band Part II : Adjacent Interference Analysis with Smart Antenna in M-WiMAX System (2.6 GHz 대역에서 M-WiMAX OFDMA/TDD 시스템과 WCDMA FDD 시스템간의 상호 간섭 분석 Part II : Adjacent Interference Analysis with Smart Antenna in M-WiMAX System)

  • Wang, Yu-Peng;Ko, Sang-Jun;Chang, Kyung-Hi
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.6A
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    • pp.588-599
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    • 2007
  • This paper presents the coexistence issues between M-WiMAX TDD and WCDMA FDD systems. To improve the M-WiMAX system performance and to reduce the adjacent channel interference to WCDMA FDD system, transmit and receive beamforming techniques are applied in the base stations of M-WiMAX system. Furthermore, we propose an adjacent channel interference modeling methodology, which captures the effect of transmit beamforming on the adjacent channel interference. Besides, we verify the performance improvement in the uplink of WCDMA system due to the transmit beamforming in M-WiMAX downlink based on the proposed adjacent channel interference modeling methodology. We also verify the performance enhancement due to the receive beamforming in the uplink of M-WiMAX system through system level Monte Carlo simulations, considering random user position, the effect of shadowing and multi-path fading channel. Discussions on the gain of applying transmit and receive beamforming in M-WiMAX system comparing the case of SISO system are also included. Furthermore, we present the performance of cosited M-WiMAX and WCDMA systems, considering commercial deployment, additional channel filter at base stations and the effects of TxBF and RxBF.

Implementation of a Smart Antenna Base Station for mobile-WiMAX (Mobile-WiMAX를 위한 스마트 안테나 기지국 구현)

  • Lee, Chang-Hoon;Choi, Seung-Won
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.47 no.1
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    • pp.43-52
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    • 2010
  • In this paper, the mobile-WiMAX (m-WiMAX) using the Smart antenna technique is implemented. Experiments are performed to compare Smart antenna system with conventional single antenna system. To implement the m-WiMAX smart antenna system there are many considerations, key issues of which are symbol time acquisition, beamforming, calibration. In the paper, symbol time acquisition, beamforming, calibration are implemented in WiMAX Smart antenna system and we verified that Smart antenna system is superior to single antenna system. The experimental results show 5.5 dB performance enhancement of implemented Smart antenna system in throughput compared with a single antenna system. The experimental result is almost same as theoretical result of 6 dB.

Implementation of WiFi-to-WiBro Access Point -WiMAX CPE (WiFi-to-WiBro Access Point 구현 -WiMAX CPE)

  • Park, Chun-Kwan;Song, Han-Young;Jeon, Byung-Chun
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.9 no.5
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    • pp.53-63
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    • 2009
  • This paper is to develop WiMAX CPE(wireless AP) that can provides Wi-Fi terminal with wireless Internet service by connecting to Wibro wireless network. This AP aims to support WiBro in upstream interface basically, and Wi-Fi and 100M Ethernet interface in downstream. So, we has developed the equipment for business that wireless ISP can provide many Internet customers with wireless Internet service by using Wi-Fi terminal in subway, car, ship, and so on, and the equipment for users that a user can purchase and then install in person. For the latter, multiple Wi-Fi terminals that be registered in WiBro service can be connected to Internet simultaneously.

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Design and Implementation of a WiMAX Connection Management and Network Monitoring Software on Linux (리눅스 상에서 WiMAX 연결 관리 및 네트워크 모니터링을 위한 소프트웨어의 설계 및 구현)

  • Lee, Moonsup;Kim, Hyoungseok;Kim, Ikhwan;Kim, Taehyoun
    • Proceedings of the Korea Information Processing Society Conference
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    • 2009.11a
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    • pp.499-500
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    • 2009
  • 최근 차세대 휴대 인터넷 기술로 WiMAX (Worldwide Interoperability for Microwave Access)가 주목을 받고 있으며 성능 향상을 위한 많은 연구가 진행되고 있다. WiMAX의 성능향상을 위해서는 실제 네트워크 환경에서 연구가 수행되어야 하지만 아직 연구 목적으로 사용할 수 있는 소프트웨어가 부족하다. 본 연구에서는 WiMAX 네트워크의 연결을 관리하고, 연결된 WiMAX 네트워크의 환경 및 PHY/MAC 계층의 정보를 모니터링할 수 있는 소프트웨어인 WiMAX CM(Connection Manager)를 개발하였다. 개발된 WiMAX CM은 확장성을 고려하여 핵심 기능이 SDK(Software Development Kit)형태로 설계되었으며 다양한 WiMAX 네트워크 연결을 위해 접속 프로파일을 관리하고, 네트워크 정보를 실시간으로 모니터링하여 사용자에게 제공한다.

Joint Scheme of IQ Imbalance Compensation and AGC for Optimal DFE in M-WiMAX Mobile Modem (M-WiMAX 시스템의 DFE 최적화를 위한 IQ 불균형 보상과 AGC 결합 기법)

  • Kim, Jong-Hun;Kim, Young-Bum;Chang, Kyung-Hi
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.5A
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    • pp.341-346
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    • 2009
  • M-WiMAX (Mobile-Worldwide Interoperability for Microwave Access) system, which uses OFDM (Orthogonal Frequency Division Multiplexing) technique, is known to be proper for mobile high-speed data transmission system. Nevertheless, M-WiMAX is seriously sensitive to IQ imbalance caused by the LO (Local Oscillator) at the receiver. In this paper, we analyze the effect of IQ imbalance on the system, and then propose a joint optimization scheme that can optimize DFE (Digital Front-end) of mobile modem by combining operation duplicated between AGC (Automatic Gain Control) and the estimation and compensation of IQ imbalance. Simulation results show that the proposed scheme achieves the same performance of the conventional scheme while reducing the complexity of the H/W implementation.

Frame Synchronization for Mobile WiMAX Femtocells Using IEEE802.11 Based Wireless Backhaul (IEEE 802.11 기반의 무선 백홀을 사용하는 Mobile WiMAX 펨토셀을 위한 프레임 동기화 기법)

  • Choi, Ji-Hoon;Oh, Hyuk-Jun;Yun, Jae-Yeun;Ko, Hyun-Mo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.8C
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    • pp.667-679
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    • 2010
  • The use of femtocells in buildings and homes has been widely studied as a means to enlarge the cell coverage and increase the network capacity of mobile communication systems. Femtocells for Mobile WiMAX (M-WiMAX) using time division duplexing (TDD) requires frame synchronization with neighboring base stations to avoid interference between uplink and downlink signals. In this paper, we propose a new frame synchronization method for femtocell using IEEE 802.11 based wireless backhaul, which transfers the time information of mobile network to femtocells via the beacon signal provided by IEEE 802.11. Also, in order to reduce timing error of the proposed method, we modify the collision avoidance scheme in the transmitter of IEEE 802.11 and apply a timing estimation technique designed in the sense of least squares to the receiver of IEEE 802.11. Through computer simulations using the proposed scheme, we evaluate the performance of frame synchronization for femtocells and show that the recovered timing information satisfies the timing specification defined by M-WiMAX standard.

Adjacent Interference Analysis between M-WiMAX OFDMA/TDD and WCDMA FDD System in the 2.6 GHz Band Part I : Adjacent Interference Analysis in SISO System (2.6 GHz 대역에서 M-WiMAX OFDMA/TDD 시스템과 WCDMA FDD 시스템간의 상호 간섭 분석 Part I : SISO 시스템에서의 상호 간섭 분석)

  • Ko, Sang-Jun;Wang, Yu-Peng;Chang, Kyung-Hi
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.6A
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    • pp.573-587
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    • 2007
  • In this paper, we analyze the adjacent interference between WCDMA and M-WiMAX systems in the 2.6GHz Band under the SISO (Single Input Single Output) configuration. The interference scenarios are characterized into 8 scenarios with different victim and interfering links. Among the 8 scenarios, we find that the most performance loss is observed in the scenarios of victim uplink suffering interference from downlink in both systems. Besides, guard band is applied to mitigate the adjacent interference in all the scenarios. Especially, we reveal that M-WiMAX system is much more sensitive to adjacent interference than WCDMA system due to the lower transmission power. In this paper, we consider the worst interference environment, where interferers always transmit with the maximum power, a loose spectrum mask is adapted, and no additional channel fitters are equipped in both systems.

Error Handling and Data Synchronization in Policy and Charging Control Architecture in WiMAX (WiMAX 정책 제어 시스템의 정보 동기화)

  • Seol, Soonuk;Cho, Sungsoo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38B no.5
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    • pp.355-367
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    • 2013
  • In the Policy and Charging Control(PCC) architecture of the 3GPP and WiMAX forum, the Policy and Charging Rule Function(PCRF) controls and configures the policies of quality of services(QoS) and accounting to a Policy and Charging Rule Enforcement Function(PCEF). In this paper, we categorize the errors into three types that include a disconnection with peer entity, a delayed or no response and a response with failure result, and propose a scheme to automatically synchronize the data between the PCRF and the PCEF for each type of error. Also, we conduct a quantitative analysis to see how much it can help to maintain the cell capacity of the mobile VoIP service in a WiBro network, which is implemented in Korea according to the standards of WiMAX. We can see that our proposed scheme improves the performances of PCC by preventing the waste of radio resources, the overload of systems, the memory leakage of servers, the system shutdown, and so on. We have validated the scheme by implementation, and reflected it in WiMAX standard documents.

Performance Analysis of the TCP Congestion Control Algorithms over WiMAX Networks (WiMAX 네트워크 상에서 TCP 혼잡제어 알고리즘간 성능 비교 분석)

  • Lee, Moonsup;Kim, Taehyoun
    • Proceedings of the Korea Information Processing Society Conference
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    • 2009.11a
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    • pp.503-504
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    • 2009
  • 최근 차세대 휴대 인터넷 기술로 주목받고 있는 WiMAX 네트워크의 성능을 향상시키기 위한 연구가 많이 진행되고 있다. WiMAX 네트워크을 이용하는 대부분의 응용들이 TCP/IP 계층을 사용하며 기존 TCP 전송기법들이 유선망을 주로 고려한 한계가 있으므로, WiMAX 네트워크 상에서의 전송 계층 성능 향상에 대한 연구의 필요성이 증대되고 있다. 본 논문에서는 실제 WiMAX 네트워크 상에서 기존 유선 네트워크에서 사용되던 TCP Reno, Veno, Westwood, Cubic 등의 TCP 혼잡제어 알고리즘들의 성능을 측정하고 비교, 분석하여 WiMAX 네트워크에서 TCP의 동작 특성을 살펴본다.

Enhancement of Hearability in Geolocation Using Mobile WiMAX Network with Interference Cancellation and Long Integration (간섭 상쇄 기법과 장기 누적 기법을 이용한 WiBro 지상파 측위 시스템의 가청성 향상)

  • Park, Ji-Won;Lim, Jeong-Min;Sung, Tae-Kyung
    • Journal of Institute of Control, Robotics and Systems
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    • v.18 no.4
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    • pp.375-383
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    • 2012
  • Together with the GPS-based approach, geolocation through mobile communication networks is a key technology for location-based service. Since the Mobile WiMAX system is considered as a candidate for fourth-generation mobile systems, it is important to investigate its location capability. The geolocation of Mobile WiMAX can be realized when the preamble symbols in the down-link channel are appropriately used for a TDOA (Time-Difference-of-Arrival) approach. However, the cellular structure of Mobile WiMAX inevitably generates co-channel interference, and it is difficult for the mobile terminal to acquire distance measurements from multiple base stations. Therefore, for geolocation via multilateration using the Mobile WiMAX network, it is very important to increase hearability. This paper proposes a geolocation method for Mobile WiMAX which employs interference cancellation and preamble signal overlapping for the enhancement of hearability. A novel interference cancellation strategy for complex-valued Mobile WiMAX signals is presented which has an iterative structure. Simulation results show that the proposed geolocation method provides the user's position with an accuracy of less than 20 m through the Mobile WiMAX cellular network if there is no multi-path or NLOS (None-Line-of-Sight).