• Title/Summary/Keyword: interference cancellation

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Multi user interference cancellation in satellite to ground uplink system Based on improved WPIC algorithm

  • Qingyang, Guan
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.11
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    • pp.5497-5512
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    • 2016
  • An improved optimal weights based on parallel interference cancellation algorithm has been proposed to cancel for interference induced by multi-user access satellite to ground uplink system. Due to differences in elevation relative motion between the user and the satellite, as well as access between users, resulting in multi-user access interference (Multi-user Access Interference, MUI), which significantly degrade system performance when multi-user access. By steepest gradient method, it obtained based on the MMSE criterion, parallel interference cancellation adjust optimal weights to obtain the maximum SINR. Compared to traditional parallel interference cancellation (Parallel Interference Cancellation, PIC) algorithm or serial interference cancellation ( Successive interference Cancellation, SIC), the accuracy of which is not high and too many complex iterations, we establish the multi-user access to the satellite to ground up link system to demonstrate that the improved WPIC algorithm could be provided with high accuracy and relatively low number of iterations.

Linear versus Non-linear Interference Cancellation

  • Buehrer, R.Michael;Nicoloso, Steven P.;Gollamudi, Sridhar
    • Journal of Communications and Networks
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    • v.1 no.2
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    • pp.118-133
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    • 1999
  • In this paper we compare linear and non-linear inter-ference cancellation for systems employing code division multi-ple access (CDMA) techniques. Specifically, we examine linear and non-linear parallel interference cancellation(also called multi-stage cancellation) in relationship to other multiuser detection al-gorithms. We show the explicit relationship between parallel inter-ference cancellation and the decorrelator (or direct matrix inver-sion). This comparison gives insight into the performance of paral-lel interference cancellation (PIC) and leads to vetter approaches. We also show that non-linear PIC approaches with explicit chan-nel setimation can provide performance improvement over linear PIC, especially when using soft non-linear symbol estimates. The application of interference cancellation to non-linear modulation techniques is also presented along with a discussion on minimum mean-squared error(MMSE) symbol estimation techniques. These are shown to further improve the performance of parallel cancella-tion.

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SSD(Simultaneous Single Band Duplex) System Using RF Cancellation and Digital Cancellation (RF Cancellation과 Digital Cancellation을 사용한 SSD(Simultaneous Single Band Duplex) 시스템)

  • An, Changyoung;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39A no.2
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    • pp.100-108
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    • 2014
  • In this paper, we design SSD(simultaneous single band duplex) system using RF(radio frequency) cancellation and digital cancellation. we analyze characteristic of residual self-interference after RF Cancellation signal when error of phase shifter occur in RF cancellation. When phase shifter error of $0^{\circ}$, $0.5^{\circ}$, $1^{\circ}$ and $2^{\circ}$ occur in RF cancellation, residual self-interference signal power after RF cancellation is bigger than desired signal power of distant station. So, it is impossible to receive transmit data of distant station. but we confirm that it is possible to receive transmit data of distant station by digital cancellation with frame structure. Also, in digital cancellation with frame structure, if residual self-interference signal after RF cancellation is too large then LMS algorithm requires more time to estimate self-interference channel. That is, performance degradation occurs because self-interference channel estimation has not completed in estimation frame.

Performance Analysis of the Multi-User Detector Employing a Hybrid Interference Cancellation Scheme in a WCDMA System (WCDMA 시스템에서 Hybrid Interference Cancellation 기법을 적용한 다중사용자 검파기의 성능분석)

  • 서정욱;오창헌;장은영;조성준
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.6 no.2
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    • pp.221-227
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    • 2002
  • In this paper, in order to know the effect of the interference, we have analyzed the BER (Bit Error Rate) performance of the MUD(Multi-User Detector) employing HIC(Hybrid Interference Cancellation) scheme for the asynchronous WCDMA system based on 3GPP(3rd Generation Partnership Project) Spec. through the In this paper, in order to know the effect of the interference, we have analyzed the BER (Bit Error Rate) performance of the MUD(Multi-User Detector) employing HIC(Hybrid Interference Cancellation) scheme for the asynchronous WCDMA system based on 3GPP(3rd Generation Partnership Project) Spec. through the computer simulation. we have assumed Rayleigh fading channel. And we have compared its BER performance with SIC's(Successive Interference Cancellation) and with PIC's(Parallel Interference Cancellation), which are the representative schemes in the subtractive interference cancellation. From the results, it is shown that PlC or HIC is effective for high data-rate users and SIC of HIC for low data-rate users to eliminate the interference. Regardless of the data rate, it is reasonable to use the HIC structure for WCDMA system to satisfy all of users' services. The reason is that the SIC scheme in front of HIC can guarantee the performance of low power users to cancel the serious interference caused by the high power users, while PIC in the rear of it can guarantee the performance of high power users to cancel the interference caused by the low power users.

Performance Analysis of Uplink Cognitive Radio Transmission based on Overloaded MC-DS-CDMA

  • Sundararajan, Mohandass;Govindaswamy, Umamaheswari
    • IEIE Transactions on Smart Processing and Computing
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    • v.3 no.4
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    • pp.181-190
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    • 2014
  • This paper reports a cognitive radio network architecture based on overloaded multicarrier direct sequence code division multiple access (O-MC-DS-CDMA). The O-MC-DSCDMA technique combines CDMA with a multicarrier modulation technique to overcome the channel fading effects. In this technique, secondary users are enabled to share the available bandwidth with the existing primary users. Two sets of orthogonal Gold codes are used to support the primary and secondary users simultaneously. The orthogonality between the spreading codes is lost due to the non-zero cross correlation between the codes and the timing synchronization error in the uplink transmission, which causes interference between primary and secondary users. This paper proposes two modified hybrid parallel/successive interference cancellation techniques for primary and secondary user base station receivers with multiple antennas to suppress the interference among users. Interference among the same group of users is cancelled by parallel interference cancellation and the interference among groups is cancelled using successive interference cancellation. The simulation results confirmed that the proposed modified interference cancellation techniques show better BER performance over conventional interference cancellation techniques.

A new interference cancellation applying widowing technique in PCS environment (PCS 환경에서 윈도우 기법을 적용한 새로운 직렬 간섭 제거 기술)

  • 도상현;김의묵;최형진
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.22 no.11
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    • pp.2388-2400
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    • 1997
  • In this paper, we analyzed the serial interference cancellation scheme and proposed the new serial interference cancellation scheme suppressing multiple access interference. Compensating for the near-far effect and the multiple access interference is critical for the stable performance of DS/CDMA system, and the serial multiple access interference cancellation has been proposed as one of the compensation methods. But this serial interference cancellation scheme has a linear variation in the number of cancellation operation each users. Becaure of this variation, it is difficult to show a stable performance. Hence, we suggested a new serial interference applying window technique to overcome this fault and made a performance estiamation.

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Performance Enhancement Technique in Visible Light Communication System for Smart Building (스마트 빌딩을 위한 가시광 통신 시스템의 성능 향상 기법)

  • Seo, Sung-Il
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.20 no.5
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    • pp.39-43
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    • 2020
  • In this paper, we propose the multi-channel interference cancellation algorithm for visible light communication (VLC) in smart building. The VLC system is communication technology using visible rays that come out in Light Emitting Diode (LED) device. It has energy curtailment effect and possible to use in ubiquitous network service applications. When a large number of users communicate indoors, the performance can be reduced due to channel interference. To remove interference, at the first, the minimum mean square error (MMSE) scheme as interference cancellation methods used, and then the successive interference cancellation (SIC) is applied to obtain additional diversity gain and improve interference cancellation performance. Indoor VLC channel model is employed. The performance is evaluated in terms of bit error rate (BER). From the simulation results, it is confirmed that the proposed scheme has better BER performance compared to the previous systems. As a result, the proposed interference cancellation improves the signal quality of VLC systems by effectively removing the channel noise. The results of the paper can be applied to VLC for smart building and general communication systems.

Design and Performance Analysis of Hybrid Receiver based on System Level Simulation in Backhaul System (백홀 시스템에서 시스템 레벨 시뮬레이션 기반 하이브리드 수신기 설계 및 성능 분석)

  • Moon, Sangmi;Choe, Hun;Chu, Myeonghun;Kim, Hanjong;Hwang, Intae
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.5
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    • pp.23-32
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    • 2015
  • The advanced receiver which can manage inter-cell interference is required to cope with the explosively increasing mobile data traffic. 3rd Generation Partnership Project (3GPP) has discussed network assisted interference cancellation and suppression (NAICS) to improve signal-to-noise-plus-interference ratio (SINR) and receiver performance by suppression or cancellation of interference signal from inter-cells. In this paper, we propose the novel hybrid receiver Full Suppression Cancellation (FSC) to reduce the interference from neighbor cell in backhaul system. The proposed receiver can suppress and cancel the interference by combining Interference Rejection Combining (IRC) with Successive Interference Cancellation (SIC). We perform the system level simulation based on 20MHz bandwidth of 3GPP LTE-Advanced system. Simulation results show that the proposed receiver can improve error rate and throughput of conventional system.

On-Frequency Repeater using Interference Cancellation System (적응성 간섭잡음제거기를 이용한 동일 주파수 중계기)

  • 김선진;이제영;이종철;김종헌;이병제;김남영
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2002.11a
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    • pp.177-181
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    • 2002
  • In this paper, the cancellation or suppression of the feedback interference from Tx antenna using the same frequency is studied. The major problems on the wireless communication system using the same frequency or on-frequency repeater (OFR) are the coupling and isolation between Rx and Tx antenna. In order to increase the isolation between Rx and Tx antenna and to Prevent the self-oscillation of the receiver system, this paper is verified the possibility of the application of interference cancellation system and proposed the design method of the OFR using interference cancellation system.

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Joint Precoding Technique for Interference Cancellation in Multiuser MIMO Relay Networks for LTE-Advanced System (LTE-Advanced 시스템의 다중 사용자 MIMO Relay 네트워크에서 간섭 제거를 위한 Joint Precoding 기술)

  • Malik, Saransh;Moon, Sang-Mi;Kim, Bo-Ra;Kim, Cheol-Sung;Hwang, In-Tae
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.49 no.6
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    • pp.15-26
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    • 2012
  • In this paper, we perform interference cancellation in multiuser MIMO (Multiple Input Multiple Output) relay network with improved Amplify-and-Forward (AF) and Decode-and-Forward (DF) relay protocols. The work of interference cancellation is followed by evolved NodeB (eNB), Relay Node (RN) and User Equipment (UE) to improve the error performance of whole transmission system with the explicit use of relay node. In order to perform interference cancellation, we use Dirty Paper Coding (DPC) and Thomilson Harashima Precoding (THP) allied with detection techniques Zero Forcing (ZF), Minimum Mean Square Error (MMSE), Successive Interference Cancellation (SIC) and Ordered Successive Interference Cancellation (OSIC). These basic techniques are studied and improved in the proposal by using the functions of relay node. The performance is improved by Decode-and-Forward which enhance the cancellation of interference in two layers at the cooperative relay node. The interference cancellation using weighted vectors is performed between eNB and RN. In the final results of the research, we conclude that in contrast with the conventional algorithms, the proposed algorithm shows better performance in lower SNR regime. The simulation results show the considerable improvement in the bit error performance by the proposed scheme in the LTE-Advanced system.