• Title/Summary/Keyword: Co-Channel Interference

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Error Rate Performance Variation by the Reception Phase Error in a Frequency-Selective Rayleigh Fading Channel Environment (주파수 선택성 레일리 페이딩 채널환경에서 수신 오차위상에 의한 오율 특성 변화)

  • 김용로;금홍식;류흥균
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.30A no.9
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    • pp.6-13
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    • 1993
  • In is well-known that system performance in the high speed digital radio communication system is usually deteriorted due to the frequency selective fading distortion. In this paper, bit error rate(BER) performance by the reception phase error in cellular mobile communication systems is derived and analyzed. The system is modeled as a frequency selective fast Rayleigh fading channel corrupted by additive white gaussian noise(AWGN) and co-channel interference(CCI). Our numerical results show that for the 24KBaud(48Kb/s) $\pi$/4-DQPSK operated at carrier frequency 800 MHz and C/I<20 dB, the BER will be dominated by CCI if the vehicular speed is below 100 Km/h. The results show that performance, when reception phase error is below $\pi$/12, is deterioreted less than 3 dB, and that performance, when reception phase error is above $\pi$/12, is degraded over 3 dB.

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An Auction based Hierarchical Link Allocation Algorithm for Throughput Improvement of Relay Station Systems (Relay Station 시스템의 Throughput 향상을 위한 Auction 기반 계층적 링크 할당 알고리듬)

  • Kang, Hae-Lynn;Yu, Hye-In;Kim, Nak-Myeong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.46 no.6
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    • pp.11-18
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    • 2009
  • In this paper, a hierarchical link allocation algorithm between mobile stations (MSs) and the corresponding base station (BS) by an optimal utilization of relay stations (RSs) is proposed to improve throughput of RS systems. In the proposed hierarchical algorithm, each RS operates cognitive radio functions to sense the degree of satisfaction in the quality of services (QoSs) and then selects the candidate set of MSs to have links with the RS. Such information is reported to the BS, where an auction process is performed to get an optimal allocation of communication links between the MSs and the BS. To maximize system throughput, the proposed auction algorithm is conducted upon bidding prices of communication links, considering both the co-channel interference (CCI) information shared among adjacent cells and the QoS enhancement information for each MS collected from RSs. The BS then switches the communication links of the auction winner MSs through the corresponding RS. The computer simulation shows that the proposed algorithm enhances the user QoS more than the conventional algorithm, especially for RS systems with more users requiring higher QoS. The proposed algorithm has also been proved to have more robust performance than the conventional one when the traffic load is higher and the CCI becomes stronger.

A Study on A Mathematical Formulation of Protection Ratio and Its Calculation for Fixed Radio Relay System with Diversity (다이버시티를 갖는 고정 무선 중계 시스템에 대한 보호비의 수학적 표현과 계산에 대한 연구)

  • Suh Kyoung-Whoan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.4 s.107
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    • pp.358-367
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    • 2006
  • In this paper, a mathematical formulation of protection ratio and its calculation method are suggested for a radio relay system with diversity techniques. The analysis of protection ratio and its physical meaning have been performed for the space or frequency diversity system, and in particular protection ratios are reviewed in terms of the parameters of diversity improvement factor, which comprises antenna gain, separation distance between antennas, frequency and its difference between carriers, and distance. As one of simulated results, the co-channel protection ratio of 60 dB is obtained for the space diversity system regarding 6.2 GHz, 60 km, 64-QAM, and 25 m between antennas, which gives 15 dB less than the co-channel protection ratio of the non-space diversity system. In addition, the co-channel protection ratio for the frequency diversity system gives 64 dB in case of frequency offset of 0.5 GHz under the same conditions as the space diversity system, which brings about 11 dB less than the co-channel protection ratio of non-frequency diversity system. In consequency, it is interesting to note that the space diversity system is less sensitive to interference in comparison to the frequency diversity system and provides better quality of service for a given interference.

Downlink Power Allocation of the OFDMA Femtocell for Inter-cell Interference Mitigation (OFDMA 초소형 기지국의 인접셀 간섭을 최소화하기 위한 하향링크 전력 할당 기법)

  • Jung, Hyun-Duk;Lee, Jai-Yong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.8A
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    • pp.743-751
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    • 2010
  • OFDMA femtocell becomes an effective solution to support indoor high data rate services instead of the macrocell systems. Although the advantage of the femtocell, the co-channel interference between the femocell and the macrocell is the most significant problem that reduces the system performance. Macrocell users who have no permission to access the femtocell suffer from interference of the downlink transmission of femtocell. Therefore, the femtocell should use transmission power as small as possible to reduce interference to macrocell users. In this paper, we define the margin adaptive power allocation problem for the femtocell and propose a heuristic power allocation algorithm to solve the problem. Simulation results show the performance of the proposed algorithm.

Resource Allocation for D2D Communication in Cellular Networks Based on Stochastic Geometry and Graph-coloring Theory

  • Xu, Fangmin;Zou, Pengkai;Wang, Haiquan;Cao, Haiyan;Fang, Xin;Hu, Zhirui
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.12
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    • pp.4946-4960
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    • 2020
  • In a device-to-device (D2D) underlaid cellular network, there exist two types of co-channel interference. One type is inter-layer interference caused by spectrum reuse between D2D transmitters and cellular users (CUEs). Another type is intra-layer interference caused by spectrum sharing among D2D pairs. To mitigate the inter-layer interference, we first derive the interference limited area (ILA) to protect the coverage probability of cellular users by modeling D2D users' location as a Poisson point process, where a D2D transmitter is allowed to reuse the spectrum of the CUE only if the D2D transmitter is outside the ILA of the CUE. To coordinate the intra-layer interference, the spectrum sharing criterion of D2D pairs is derived based on the (signal-to-interference ratio) SIR requirement of D2D communication. Based on this criterion, D2D pairs are allowed to share the spectrum when one D2D pair is far from another sufficiently. Furthermore, to maximize the energy efficiency of the system, a resource allocation scheme is proposed according to weighted graph coloring theory and the proposed ILA restriction. Simulation results show that our proposed scheme provides significant performance gains over the conventional scheme and the random allocation scheme.

Relay Protocol applied to Optimal Power Allocation (최적의 전력 분배 방안이 적용된 중계기 프로토콜)

  • Kim, Tae-Wook;Kong, Hyung-Yun
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.15 no.4
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    • pp.93-97
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    • 2015
  • In this Paper, we proposed optimization of system performance, optimal splitting factor applied to power splitting protocol with relay in the cooperative communication undergo co-channel interference. We can possible to optimize and maximize the channel capacity of the receiver through optimal factor of splitting protocol. So, we can solve inability in system, and to increase the efficiency of the network. Finally, performance of the proposed protocol is analyzed in terms of outage probability, capacity of system.

A Predistortion Linearizer which is composed of common-gate MESFET circuits (공통 게이트 회로로 구성된 MESFET 전치왜곡 선형화기)

  • Jeung, Seung-Il;Kim, Han-Suk;Kang, Jeung-Jin;Lee, Jong-Arc
    • Journal of IKEEE
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    • v.4 no.2 s.7
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    • pp.241-248
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    • 2000
  • A linear power amplifier is particular emphasized on the CDMA system using a linear modulation scheme, because intermodulation distortion which cause adjacent channel interference and co channel interference is mostly generated in a nonlinear power amplifier. In this paper, a new type of linearization technique proposed. It is presented that balanced MESFET predistortion linearizer added. Experimental result are present for Korea PCS(Personal Communication Service) frequency band. The implemented linearizer is applied to a 30dBm class A power amplifier for simulation Performance. The predistortion linearizer improves the 1dB compression point of the HPA about 2dBm, and intermoudulation distortion about 12.5dBc.

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Design of Predistortion Linearizer using Common-Gate MESFET (공통 게이트 MESFET를 이용한 전치왜곡 선형화기 설계)

  • 주성남;박청룡;최조천;최충현;김갑기
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2003.10a
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    • pp.53-56
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    • 2003
  • A linear power amplifier is particularly emphasized on the CDMA system using a linear modulation scheme, because IMD which cause adjacent channel interference and co channel Interference is mostly generated in a nonlinear power amplifier. In this paper, a new type of linearization technique proposed. It is presented that balanced MESFET predistortion linearizer added. Experimental result are present for Korea PCS frequency band. The implemented linearizer is applied to a 30dBm class. A power amplifier for simulation performance. Two-tone signals at 1850 MHz and 1851.23 MHz are injected into the main power amplifier. The main power amplifier with a 12.1dB gain and a P1dB of 30 dBm(two-tone) was utlized. The reduction of IMD is around 22dB.

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A Study on Multi-Site Radar Operations Based on LFM Signal (LFM 신호에 기반한 다중국소 레이더 운영에 관한 연구)

  • Suh, Kyoung-Whoan
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.15 no.3
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    • pp.91-98
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    • 2015
  • As one of solutions to obtain efficient use of limited spectrum resource, we suggest a methodology for the co-channel multi-site radar operations with a shifted linear frequency modulation (SLFM) based on GPS clock. The proposed algorithm is that we find a candidate set of SLFM signals with the minimum acceptable level of the correlation from the cross-correlation characteristics among selected SLFM signals. To verify the proposed methodology, numerical analysis has been accomplished for several radars operating in the same channel with a sawtooth or triangle LFM signal. The computational results of detected distances as well as range profiles are also examined for interference, noise, and algorithm limitation including the error of clock synchronization.

A study on the Design of Predistortion Linearizer using Common-Gate MESFET (공통 게이트 MESFET를 이용한 전치왜곡 선형화기 설계에 관한 연구)

  • 김갑기
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.7 no.7
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    • pp.1369-1373
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    • 2003
  • A linear power amplifier is particularly emphasized on the CDMA system using a linear modulation scheme, because IMD which cause adjacent channel interference and co channel interference is mostly generated in a nonlinear power amplifier. In this paper, a new type of linearization technique proposed. It is presented that balanced MESFET Predistortion linearizer added. Experimental result are present for Korea PCS frequency band. The implemented linearizer is applied to a 30㏈m class A power amplifier for simulation performance. Two-tone signals at 1850 MHz and 1851.23 MHz are injected into the main power amplifier. The main power amplifier with a 12.1㏈ gain and a P1㏈ of 30 ㏈m(two-tone) was utilized. The reduction of IMD is around 22㏈.