• Title/Summary/Keyword: Multiple access interference

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Interference Avoidance Resource Allocation for Device-to-Device Communication Based on Graph-Coloring (단말 간 직접 통신을 위한 그래프-컬러링 기반 간섭 회피 자원 할당 방법)

  • Lee, Changhee;Oh, Sung-Min;Park, Ae-Soon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39A no.12
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    • pp.729-738
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    • 2014
  • In this paper, we propose interference avoidance resource allocation scheme based on graph-coloring algorithm to introduce performance gain using spatial reuse in D2D (Device-to-Device) system. By assigning multiple D2D pairs to a single D2D resource, interference from neighboring D2D pairs is inevitable, which leads to performance degradation. Therefore, we first introduce the feedback information and the method considering the amount of information that can be practically provided by a D2D pair. Then, we propose how to construct a graph, which is corresponding to the D2D system, using the feedback information and adopt a graph-coloring algorithm to efficiently avoid interference. Simulation results show that the proposed resource allocation scheme outperforms traditional resource allocation schemes in both overall sum rate and spectral efficiency of D2D system while reducing the outage probability. Moreover, the outage probability, which indicates a failure rate of D2D communication, can be reduced by adopting the proposed scheme.

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.

Construction of Spread Spectrum Power Line Communication Equipment Using Power Line Synchronization (전원동기를 이용한 스펙트럼 확산 전원선 통신장치의 구성)

  • 이동욱;변건식;김명기
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.15 no.6
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    • pp.475-484
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    • 1990
  • This paper proposes a method for the implementation of a power line communication equipment using power line synchronization in a direct-sequence spread spectrum communication system. In order to implement a network using a power line as a transmission channel we have investigated the utilization of direct-sequence speread spctrum which gives such advantages as robustness against narrow-band interference and noise, and realization of multiple access. In a power line, however, complexity of synchronization makes it difficult to realize a multiple access and cost down and system simplification. The proposed technique of power line synchronization makes it possible to get cost down and system size small, and the realization of multiple communication can be achieved by the addition of address setting circuit.

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Joint Space-time Coding and Power Domain Non-orthogonal Multiple Access for Future Wireless System

  • Xu, Jin;Ding, Hanqing;Yu, Zeqi;Zhang, Zhe;Liu, Weihua;Chen, Xueyan
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.1
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    • pp.93-113
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    • 2020
  • According to information theory, non-orthogonal transmission can achieve the multiple-user channel capacity with an onion-peeling like successive interference cancellation (SIC) based detection followed by a capacity approaching channel code. However, in multiple antenna system, due to the unideal characteristic of the SIC detector, the residual interference propagated to the next detection stage will significantly degrade the detection performance of spatial data layers. To overcome this problem, we proposed a modified power-domain non-orthogonal multiple access (P-NOMA) scheme joint designed with space-time coding for multiple input multiple output (MIMO) NOMA system. First, with proper power allocation for each user, inter-user signals can be separated from each other for NOMA detection. Second, a well-designed quasi-orthogonal space-time block code (QO-STBC) was employed to facilitate the SIC-based MIMO detection of spatial data layers within each user. Last, we proposed an optimization algorithm to assign channel coding rates to balance the bit error rate (BER) performance of those spatial data layers for each user. Link-level performance simulation results demonstrate that the proposed time-space-power domain joint transmission scheme performs better than the traditional P-NOMA scheme. Furthermore, the proposed algorithm is of low complexity and easy to implement.

Dynamic Channel Allocation Considering the Interference Range in Multi-cell Downlink Systems (다중 셀 하향링크 시스템에서 간섭 영역을 고려한 동적 채널 할당)

  • Lee, Neung-Hyung;Bahk, Sae-Woong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.2A
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    • pp.179-187
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    • 2007
  • As wireless networks evolve to orthogonal frequency division multiple access(OFDMA) systems, inter-cell interference control becomes a critical issue in radio resource management. The allocation of the same channels in neighbor cells cause inter-cell interference, so the channel allocation needs to be taken carefully to lower the inter-cell interference. In distributed channel allocation, each cell independently tries to allocate channels that suffer low interference level. In this paper, under the assumption of static users, we introduce the concept of interference range and use it in designing our two algorithms; basic and combined. The basic algorithm performs interference range detection and determines whether to use the considered channel, while the combined algorithm checks the channel quality in addition to detecting the interference range. The two algorithms dynamically perform channel allocation with low complexity and show good throughput and fairness performance.

Performance Evaluation of Time Hopping Binary PPM Impulse Radio System according to Interference Environment (간섭 환경에 따른 TH Binary PPM IR 시스템의 성능 평가)

  • Lee, Yang-Sun;Kang, Heau-Jo
    • Journal of Advanced Navigation Technology
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    • v.6 no.4
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    • pp.318-325
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    • 2002
  • In this paper, the effects of the interference environments on the performance of the time hopping(TH) binary PPM impulse radio(IR) system are presented. Based on the monocycle pulse available within the frequency of 3.1~10.6 GHz permitted for application by FCC, a PPM-modulated TH IR system simulator was designed and followed by the analysis of the monocycle pulse characteristics as well as the system performance. Particularly for the evaluation of the system performance, the multiple access interference and the narrowband system interference signals were considered as the interference signals. Since the narrowband system interference signal has very narrow bandwidth and very large amplitude compared with those of IR system, the analysis of the IR system performance was implemented by considering the interference power and band fraction ratio of the narrowband interference signal.

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Up/Downlink Hybrid Inter-Cell Coordination Patterns of the TDD/MC-CDMA System, TDD/MC-CDMA

  • Han, Sang-Jin;Lee, Sung-Jin;Lee, Sang-Hoon;Gil, Gye-Tae
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.5A
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    • pp.421-428
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    • 2009
  • Inter-cell coordination has been an emerging issue for mitigating inter-cell interference in broadband wireless access networks such as IEEE802.16 and 3GPP LTE (Long Term Evolution). This paper proposes uplink/downlink hybrid inter-cell coordination patterns for a TDD (Time Division Duplex)/MC-CDMA (Multi-Carrier Code Division Multiple Access) system. For the performance analysis, closed forms of inter-cell interferences are derived when uplink and downlink transmissions coexist over a multi-cell environment. In the analysis, we find an optimal ratio of downlink transmit powers of BSs (Base Stations) based on the target outage probability and the performance according to ratios of uplink/downlink transmit powers of MSs (Mobile Stations)/BSs is explored. Our numerical results show that interference mitigation utilizing the characteristics of the uplink and downlink power ratio is very effective in improving system performance in terms of QoS.

Implementation of IEEE 802.15.4 Channel Analyzer for Evaluating WiFi Interference (WiFi의 간섭을 평가하기 위한 IEEE 802.15.4 채널분석기의 구현)

  • Song, Myong-Lyol;Jin, Hyun-Joon
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.63 no.2
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    • pp.81-88
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    • 2014
  • In this paper, an implementation of concurrent backoff delay process on a single chip with IEEE 802.15.4 hardware and 8051 processor core that can be used for analyzing the interference on IEEE 802.15.4 channels due to WiFi traffics is studied. The backoff delay process of IEEE 802.15.4 CSMA-CA algorithm is explained. The characteristics of random number generator, timer, and CCA register included in the single chip are described with their control procedure in order to implement the process. A concurrent backoff delay process to evaluate multiple IEEE 802.15.4 channels is proposed, and a method to service the associated tasks at sequentially ordered backoff delay events occurring on the channels is explained. For the implementation of the concurrent backoff delay process on a single chip IEEE 802.15.4 hardware, the elements for the single channel backoff delay process and their control procedure are used to be extended to multiple channels with little modification. The medium access delay on each channel, which is available after execution of the concurrent backoff delay process, is displayed on the LCD of an IEEE 802.15.4 channel analyzer. The experimental results show that we can easily identify the interference on IEEE 802.15.4 channels caused by WiFi traffics in comparison with the way displaying measured channel powers.

A Study on the New Hybrid Interference Cancellation Scheme for Multirate DS-CDMA (다중전송률 DS-CDMA 시스템을 위한 새로운 하이브리드 간섭제거기)

  • Kim, Nam-Sun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.9C
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    • pp.1219-1226
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    • 2004
  • The objective of this paper is to proposed a new Hybrid Interference Cancellation(HlC) receiver to cancel MAI in a multirate DS-CDMA system based on multiple processing gain(MPG). We propose a new improved HIC scheme that divides the active users with different data rates split into a number of groups for effectives cancellation Between each group, GW-PIC is performed to cancel other group signals and within them, SIC is carried out to remove multiple access interference in group. We analyze the performance of the proposed receiver in terms of the bit error rate(BER) and examine its performance. As a conclusion, computer simulations show that the proposed schemes outperforms adaptive multistage PIC and conventional SIC receiver over AWGN channel.