• Title/Summary/Keyword: interference cancellation

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Interference Cancellation System to Prevent the Oscillation of the Wireless Communication System using the Same Frequency (동일 주파수 무선통신 시스템의 발진방지를 위한 간섭잡음제거기)

  • 김선진;김남영
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.3
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    • pp.253-262
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    • 2003
  • In this paper, the interference cancellation system, which is used to cancel the feedback signal in the wireless communication system with the same frequency, is studied. The time varying feedback signal generated from transmitter antenna to receiver antenna reduces the performance of the receiver system. the interference cancellation system using adaptive feedback method(AF-ICS) is suggested to prevent the oscillation of the receiver system and maintain the maximum output power of the power amplifier by the reduction of time-varying feedback signal and also this paper conforms that the oscillation disappears from the output signal by cancellation of the feedback signal and the total output power is satisfied the system specification.

Delayed Parallel Interference Cancellation for GPS C/A Code Receivers

  • Glennon, Eamonn P.;Bryant, Roderick C.;Dempster, Andrew G.
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • v.2
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    • pp.261-266
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    • 2006
  • A number of different techniques are available to mitigate the problem of cross correlations caused by the limited dynamic range of the 10-bit Gold codes in the GPS C/A code. These techniques include successive-interference cancellation (SIC) and parallel-interference cancellation (PIC), where the strong signals are subtracted at IF prior to attempting to detect the weak signals. In this paper, a variation of these techniques is proposed whereby the subtraction process is delayed until after the correlation process, although still employing a pure reconstructed C/A code signal to permit prediction of the cross correlation process. The paper provides details on the method as well as showing the results obtained when the method was implemented using a software GPS receiver. The benefits of this approach are also described, as is the application of the method to the cancellation of CW interference.

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Hybrid Interference Cancellation for OFDMA Uplink in Time-Varying Fading Channels (시변 페이딩 채널에서 상향 직교 주파수 분할 다중 접속을 위한 혼합 간섭 제거 기법)

  • Song, Hyung-Joon;Hong, Dae-Sik
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.46 no.6
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    • pp.78-85
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    • 2009
  • In time-varying multipath fading channels, orthogonal frequency division multiple access (OFDMA) uplink systems suffer severe performance degradation caused by inter-channel interference (ICI). In this paper, we propose a hybrid interference cancellation (HIC) for suppressing the degradation effect of ICI. The proposed HIC can achieve both exact interference cancellation and low detection complexity through efficient combination of parallel detection and serial cancellation. Simulation results show that, as the effect of Doppler increases, the proposed HIC achieves bit error rate (BER) performance enhancement in compared with severe performance degradation of conventional OFDMA receivers. In addition, both the computational complexity and total detection time are reduced.

Performance of Interference Cancellation Scheme for Multihop Military Communication Systems (멀티 홉 군통신 시스템을 위한 간섭 제거 기법 성능 분석)

  • Kim, Yo-Cheol;Kim, Jin-Young
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.11 no.3
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    • pp.17-22
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    • 2011
  • In this paper, we analyze co-channel interference cancellation performance to be generated in multi-hop military communication system. First, remove interference using zero-forcing (ZF) and minimum mean square error (MMSE) scheme as interference cancellation methods, and then obtain additional diversity gain and improve interference cancellation performance by applying successive interference cancellation (SIC). We consider Rayleigh fading channel and system performance is analyzed as respect of bit error probability. From simulation results, we confirm MMSE improves significantly BER performance than ZF in multi-hop wireless network environment. It is also confirmed ZF and MMSE schemes applying SIC algorithm have better performance comparing to the existing schemes. Therefore, MMSE-SIC method can provide more reliable signal transmission in the multi-hop military communication system.

A Study on Hybrid Interference Cacellation for Multirate DS-CDMA (Multirate DS/CDMA 시스템을 위한 하이브리드 간섭제거기법에 관한 연구.)

  • 유종엽;이승호;우대호;변윤식
    • Proceedings of the IEEK Conference
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    • 2000.09a
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    • pp.47-50
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    • 2000
  • In the Multirate DS/CDMA system based on VSL(Variable Spreading Length), the problem of the multiple access interference and effect similar to near-far effects in current system is generated. This problem can degrade performance of the system badly. Therefore, In this paper we proposed Hybrid Interference Cancellation to overcome this problems, Simulation result presents that the proposed Hybrid Interference Cancellation has the better performance than the conventional decorrelator, Parallel Interference Cancellation.

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Multipath Interference Cancellation Algorithm in WCDMA forward link (WCDMA 순방향 링크에서의 다중 경로 간섭 제거 알고리즘)

  • 유현규;권종형;류탁기;홍대식;강창언
    • Proceedings of the IEEK Conference
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    • 2001.06a
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    • pp.353-356
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    • 2001
  • In WCDMA systems, it is difficult to use high level modulation schemes in Rayleigh fading channel. Components of Multipath interference give signals much inteferences. Multipath interference cancellation is one of the method to overcome this problem. In this paper, multistage PIC algorithm is used to verify a performance of multipath interference cancellation. It is algorithm gradually canceling the multipath interferences as a stage number is increases. In computer simulations, it is verified that multipath interference cancelation is necessary and using its algorithm give much better performances than not using.

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Performance Evaluation of Multi-User Detectors Employing Subtractive Interference Cancellation Schemes for a DS-CDMA System (감산형 간섭제거기법을 적용한 DS-CDMA 다중사용자 검파기의 성능분석)

  • Seo, Jung-Wook;Kim, Young-Chul;Oh, Chang-Heon;Ko, Bong-Jin;Cho, Sung-Joon
    • Journal of Advanced Navigation Technology
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    • v.6 no.1
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    • pp.17-26
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    • 2002
  • In this paper, we have analyzed the BER (Bit Error Rate) performance of multi-user detectors employing SIC(Successive Interference Cancellation) and PIC (Parallel Interference Cancellation) which are the representative schemes in the subtractive interference cancellation. We have considered the MUD structure employing HIC (Hybrid Interference Cancellation) which combines SIC with PIC scheme, and then analyzed the BER performance. We have evaluated the BER performance of SIC and HIC schemes which execute the soft decision to generate the tentative data bit for the purpose of the interference cancellation in MAI and noise environments. Through the numerical analysis and computer simulation, it is shown that HIC can remove the effect of MAI more efficiently than the others, that improve the BER performance and increase the capacity of DS-CDMA systems regardless of the power control conditions. The reason is that the SIC scheme in front of HIC can solve the near-far problem caused by the imperfect power control and PIC scheme in the rear of it can improve the performance much more.

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Self-Interference Cancellation and Turbo Equalizer Design for the Single-band Full Duplex System using Single Antenna (단일 안테나를 사용하는 단일대역 전이중 통신을 위한 자기간섭신호제거와 터보 등화기 설계)

  • Choi, Jinkyu;An, Changyoung;Ryu, Heung-Gyoon
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.2
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    • pp.7-17
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    • 2015
  • In this paper, we propose a single antenna SSD(simultaneous single band duplex) system using turbo equalizer. The proposed system communicates simultaneously on single band. That is the proposed system is full-duplex system. The proposed system uses balanced feed network circuit to improve isolation in single antenna structure. Also, the proposed system uses RF(radio frequency) cancellation and digital cancellation to cancel self-interference. Additionally, the proposed system uses turbo equalizer to equalize ISI(inter-symbol interference) by harsh multipath fading and to collect bit errors by residual self-interference signals. By using turbo equalizer, the proposed system guarantees QoS(quality of service). In this paper, we uses Simulink simulation program to analyze performance of the proposed system. The simulation results confirm that proposed system can communicate simultaneously by using balanced feed network, RF cancellation, digital cancellation and turbo equalizer in harsh multipath channel on single band.

Improvement of Applebaum Array Interference Cancellation in Smart Antenna System by Using Covariance Matrix Adjustment

  • Tanakorn Sukontapong;Chuwong Phogcharoenpanich;Phaisan Ngamjanyaporn;Monai Krairiksh
    • Proceedings of the IEEK Conference
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    • 2002.07b
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    • pp.727-730
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    • 2002
  • This paper proposes the interference cancellation improvement in smart antenna system by using Applebaum array covariance matrix adjustment. This technique adds the specific adjustable multipliers with both desired signal covariance matrix and interference signal covariance matrices in order to overcome some disadvantages and improve the interference cancellation efficiency of Applebaum array. It is based on the desired and undesired signal power or desired signal-to-interference-plus-thermal noise ratio (SINR). As the result from demonstration, the proposed technique can improve and increase the interference cancellation efficiency in smart antenna better than the conventional technique.

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Interference Cancellation Based on Adaptive Signal Processing for MIMO RF Repeaters (MIMO RF 중계기를 위한 적응 신호처리 기반의 간섭 제거)

  • Lee, Kyu-Bum;Choi, Ji-Hoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.9C
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    • pp.735-742
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    • 2010
  • In this paper, we propose adaptive algorithms for interference cancellation in RF repeaters with multiple transmit and receive antennas. When multiple antennas are used in a repeater, the imperfect isolation between transmit and receive antennas causes the feedback interference which is modeled as multi-input multi-output (MIMO) channel. To remove the feedback interference, we derive the least mean square (LMS) algorithm and the recursive least squares (RLS) algorithm for interference cancellation based on adaptive signal processing techniques. Through computer simulations for the proposed algorithms, we analyze the convergence characteristics and compare the steady-state performance for interference cancellation.