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Effect of inter-cluster interference on fracture morphology in multi-cluster staged fracturing for shale reservoir

FRATTURA ED INTEGRITA STRUTTURALE 2018年第44期12卷 35-48页

作者： Li, Qing-Chao Cheng, Yuan-Fang Zhou, Dong-Xian Li, Qiang Ansari, Ubedullah China Univ Petr East China Sch Petr Engn Qingdao 266580 Shandong Peoples R China

Multi-cluster staged fracturing technology is an effective measure to stimulate the reservoir properties. However, the inter-cluster interference effect is obvious when the cluster spacing is very narrow, which seriously affects the effect of fracturing. In order to understand the interference among fracturing clusters within the single fracturing section of the shale horizontal wells during multi-cluster staged fracturing, a finite element model is developed by using ABAQUS finite element simulation software. On this basis, the influences of factors on the fracture morphology are studied. The simulation results have shown that the cluster spacing is the most important factor affecting inter-cluster interference. With the increase in the distance between adjacent clusters, the interference among the fracturing fractures decreases and the propagation of different fractures become homogeneous or similar. Moreover, the increase in the elastic modulus of the shale formation promotes the propagation of the fractures longitudinally, but it hinders the crack opening of the fracture laterally. In addition, properly increasing the injection rate of fracturing fluid during fracturing is more advantageous for obtaining long and wide fractures. Besides, the effect of the fracturing fluid viscosity on fracture width is greater than that on the fracture half-length. The simulation results show the existence of inter-cluster interference comprehensively, which can provide a reference for the design and optimization of multi-cluster staged fracturing to some extent.

关键词： Multi-cluster staged fracturing inter-cluster interference Shale gas reservoir Finite element method

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Iterative Soft Intra-cluster interference Cancellation for Cell-Free Massive MIMO Networks 19

Iterative Soft Intra-Cluster Interference Cancellation for C...

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19th international Symposium on Wireless Communication Systems (ISWCS)

作者： Ssettumba, Tonny Mashdour, Saeed Landau, Lukas T. N. da Silva, Paulo Branco de Lamare, Rodrigo C. Pontificia Univ Catolica Rio de Janeiro CETUC DEE Rio de Janeiro Brazil CPqD Campinas Brazil

ISBN: (纸本)9798350362527;9798350362510

This work proposes soft iterative parallel interference cancellation (PIC) for clustered cell-free massive multiinput multi-output (MIMO) networks to mitigate intra-cluster interference. In particular, we derive new closed-form expressions for minimum mean square error linear receive filters with PIC (MMSE-PIC) receivers by assuming the presence of inter-cluster interference (ICI), channel estimation errors and additive white Gaussian noise. The derived expressions are used to develop the resulting receivers by varying the number of iterations and assuming perfect and imperfect channel state information. By determining the mean and variance of the detected signals, new closed-form expressions for the Gaussian approximation of the likelihood function are also obtained. Simulations evaluate both clustered and full cell-free mMIMO networks equipped with the proposed cluster-based MMSE-PIC and linear MMSE receivers in terms of bit error rate (BER) and complexity.

关键词： Iterative clustered cell-free systems intra-cluster interference inter-cluster interference Soft MMSE with parallel interference cancellation receiver.

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Effective User clustering and Power Control for Multiantenna Uplink NOMA Transmission

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2022年第11期21卷 8995-9009页

作者： Liu, Ming Zhang, Junxia Xiong, Ke Zhang, Mingshan Fan, Pingyi Letaief, Khaled B. Beijing Jiaotong Univ Engn Res Ctr Network Management Technol High Spee Sch Comp & Informat Technol Minist Educ Beijing 100044 Peoples R China Beijing Jiaotong Univ State Key Lab Rail Traff Control & Safety Beijing 100044 Peoples R China Intel Res Ctr Beijing 100080 Peoples R China Tsinghua Univ Beijing Natl Res Ctr Informat Sci & Technol Beijing 100084 Peoples R China Tsinghua Univ Dept Elect Engn Beijing 100084 Peoples R China Hong Kong Univ Sci & Technol HKUST Dept Elect & Comp Engn Hong Kong Peoples R China Peng Cheng Lab Shenzhen 518055 Peoples R China

This paper investigates the user clustering and power control in the uplink multiple-input single-output non-orthogonal multiple access (MISO-NOMA) networks. A joint optimization problem is formulated to minimize the system transmit power. The formulated optimization problem is prohibitively complicated, especially when the number of users is large. Alternatively, a two-step user clustering and power control algorithm is proposed. First, a K-means-based algorithm is proposed for user clustering, where both channel gain and channel correlation among users are taken into account for the distance measurement to reduce the intra- and inter-cluster interference. Then, a semi-orthogonal user selection (SUS) algorithm is designed, with which the optimal cluster number and cluster centers can be dynamically obtained. Further, the closed-form expression of the optimal intra-cluster power control is derived, and the resulting inter-cluster power control problem is solved by designing an efficient iterative algorithm. Simulation results show that the proposed K-means-based iterative power control scheme outperforms other reference methods, and can approach the optimal performance in terms of power consumption and energy efficiency at a much lower computational complexity.

关键词： NOMA Power control interference cancellation Wireless communication clustering algorithms Optimization Correlation Non-orthogonal multiple access (NOMA) multiple-input single-output (MISO) power control user clustering inter-cluster interference

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Efficient Sleep Scheduling for Avoiding inter-cluster interference in Wireless Sensor Networks

Efficient Sleep Scheduling for Avoiding Inter-Cluster Interf...

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IEEE 9th international Conference on Mobile Ad-hoc and Sensor Networks (MSN)

作者： Luo, Hong Liao, Jianming Sun, Yan Beijing Univ Posts & Telecommun Beijing Key Lab Intelligent Telecommun Software & Beijing 100088 Peoples R China

ISBN: (纸本)9780769551593

clustering sensor nodes is an effective method for achieving high energy efficiency and flexible data aggregation in wireless sensor networks. However, scheduling all clusters to avoid the inter-cluster interference and meanwhile send all observation to the sink quickly is a difficult problem. In this paper, we use interference graph to model the inter-cluster collision problem and propose an efficient sleep scheduling mechanism in the clustered wireless sensor networks. We firstly divide the clusters into layers, then transform the cluster-tree network into the interference graph of clusters, and thereby divide all clusters on one layer into different independent sets. All clusters in the same independent set can work simultaneously without interference, while all independent sets are scheduled one by one for collision-free. To reduce the total delay of data report in the whole network, we propose three kinds of rules to sort the independent sets. Simulation and analysis show that the degree-based sorting rule works best. The practical experiments also verify this conclusion.

关键词： wireless sensor networks inter-cluster interference scheduling interference graph independent set

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Adaptive Transmission Mode Switching in interference Alignment Based clustered Wireless Network

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IEICE TRANSACTIONS ON COMMUNICATIONS 2020年第4期E103B卷 485-494页

作者： Cho, Sungyoon Seo, Jeongwook Samsung Elect Seoul South Korea Namseoul Univ Dept Informat & Commun Engn Cheonan South Korea

In this paper, hierarchical interference coordination is proposed that suppresses both intra- and inter-cluster interference (ICI) in clustered wireless networks. Assuming transmitters and receivers are equipped with multiple antennas and complete channel state information is shared among all transmitters within the same cluster, interference alignment (IA) is performed that uses nulls to suppress intra-cluster interference. For ICI mitigation, we propose a null-steering precoder designed on the nullspace of a principal eigenvector of the correlated ICI channels, which eliminates a significant amount of ICI power given the exchange of cluster geometry between neighboring clusters. However, as ICI is negligible for the system in which the distance between clusters are large enough, the proposed scheme may not improve the system performance compared with the pure IA scheme that exploits all spatial degrees of freedom (DoF) to increase multiplexing gain without ICI mitigation. For the efficient interference management between intra- and inter-cluster, we analyze the decision criterion that provides an adaptive transmission mode selection between pure IA and proposed ICI reduction in given network environments. Moreover, a low computational complexity based transmission mode switching algorithm is proposed for irregularly distributed networks.

关键词： interference alignment clustered wireless network inter-cluster interference interference coordination correlated MIMO channels

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Efficient Cell-clustering Algorithm for inter-cluster interference Mitigation in Network MIMO Systems

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IEEE COMMUNICATIONS LETTERS 2011年第3期15卷 326-328页

作者： Moon, Jung-Min Cho, Dong-Ho Korea Adv Inst Sci & Technol Dept Elect Engn Seoul South Korea

Coordinated transmission in network MIMO systems, in which a set of access points form a cluster and serve each user in the network, is currently the subject of a great deal of research effort. We propose a cell-clustering algorithm that aims at finding the efficient configuration of the clusters to increase the sum-rate of the users. Through simulation, we observe the improved performance of the proposed algorithm in terms of the sum-rate and the outage probability.

关键词： Network MIMO clustering coordinated transmission inter-cluster interference

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interference-Aware clustering Algorithms in Multi-Relay Cellular Networks 15

Interference-Aware Clustering Algorithms in Multi-Relay Cell...

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15th international Conference on Computational Science and Its Applications (ICCSA)

作者： Lee, Hae Sol Kim, Il-Min Kim, Dong In Kim, Seokki Lim, Kwangae Sungkyunkwan Univ SKKU Coll Informat & Commun Engn Seoul South Korea Queens Univ Elect & Comp Engn Kingston ON K7L 3N6 Canada Elect & Telecommun Res Inst Daejeon South Korea

ISBN: (纸本)9781467373678

We consider the downlink of a wireless cellular network which consists of one Macro Base Station (MBS), multiple relays and User Equipments (UEs). In this scenario, we propose relay clustering algorithms to address the problem of inter-cluster interference. In each cluster, we adopt a time-division relaying scheme to avoid intra-cluster interference, but the inter-cluster interference still remains. In interference-aware network, an optimal clustering algorithm requires an exhaustive search, which is infeasible. Hence, we propose a clustering algorithm which improves the system capacity by exploiting the inter-cluster information. But this algorithm is implemented in a centralized manner with high complexity that requires the calculation of inter-cluster information. To circumvent this, we propose a cluster-wise distributed algorithm with manageable complexity, which shows the performance within acceptable range from the optimal one, far better than simple and intuitive algorithms because of the effect of inter-cluster interference.

关键词： inter-cluster interference interference-aware clustering cluster-wise distributed algorithm

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Relay Selection in Multiple clustered Relay Networks 14

Relay Selection in Multiple Clustered Relay Networks

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Wireless Telecommunications Symposium (WTS)

作者： Kim, Woo Suk Kim, Woo Jin Lee, Hae Sol Kim, Il Min Kim, Dong In Kim, Seokki Lim, Kwangae Sungkyunkwan Univ SKKU Coll Informat & Commun Engn Seoul South Korea Queens Univ Elect & Comp Engn Kingston ON K7L 3N6 Canada Elect & Telecommun Res Inst Daejeon South Korea

ISBN: (纸本)9781479967766

We consider the downlink of a realistic cellular network composed of multiple clusters, each of which includes multiple relays and a destination terminal. In this scenario, the interference among the clusters is a critical issue, affecting the end-to-end performance of the system significantly. Considering the inter-cluster interference, we propose optimal and suboptimal relay selection schemes to maximize the sum rate of the network. The first algorithm is a truly optimal network-wise relay selection scheme which provides the ultimate performance upper bound. However, the computational complexity and the signaling overhead involved with the optimal scheme are fairly high. Addressing the issues, we propose a suboptimal cluster-wise scheme with a much less computational complexity and signaling overhead. Numerical results demonstrate that the proposed algorithms provide excellent performance.

关键词： clustered relay networks mutual information inter-cluster interference relay selection

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On the Capacity of cluster-Based Cooperative MIMO Cellular System with Universal or Fractional Frequency Reuse

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WIRELESS PERSONAL COMMUNICATIONS 2014年第2期74卷 891-908页

作者： Piao, Dazhi Commun Univ China Dept Commun Engn Beijing 100024 Peoples R China

The information-theoretic capacity for the cluster-based multicell cooperative processing (MCP) network with inter-cluster interference is investigated in this paper. An upper bound for the ergodic capacity is derived by the QR decomposition of the channel matrix, which is concisely expressed and close to the results from numerical simulations. Capacity results for the universal frequency reuse (UFR) network show that the cluster-based MCP system has great advantages over the non-cooperated system, and the capacity gain depends mainly on the size of the cooperative cluster, the radius of the cell and the path loss exponent (PLE). However, the cluster-based UFR system is still interference limited, whose capacity declines sharply due to the inter-cluster interference. Therefore, a cluster-based fractional frequency reuse (FFR) network is proposed to improve the system capacity, simulation results show that the cluster-based FFR system can outperform the UFR system, especially for the cases of small radius of cell or small PLE.

关键词： Multicell cooperative processing network Capacity inter-cluster interference Fractional frequency reuse

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inter-cluster Design of Precoding and Fronthaul Compression for Cloud Radio Access Networks

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IEEE WIRELESS COMMUNICATIONS LETTERS 2014年第4期3卷 369-372页

作者： Park, Seok-Hwan Simeone, Osvaldo Sahin, Onur Shamai, Shlomo New Jersey Inst Technol Dept Elect & Comp Engn ECE Ctr Wireless Commun & Signal Proc Res CWCSPR Newark NJ 07102 USA InterDigital Inc Melville NY 11747 USA Technion Israel Inst Technol Dept Elect Engn IL-32000 Haifa Israel

This work studies the joint design of precoding and fronthaul compression for the downlink of multi-cluster cloud radio access networks (C-RANs). In these systems, each cluster of radio units (RUs) is managed by a different control unit (CU) through fronthaul links of limited capacity. Each CU performs baseband processing, including channel coding and linear precoding, for all the connected RUs, and then compresses the pre-coded signals for transmission to the RUs over the corresponding fronthaul links. In a recent work, it was shown that joint, rather than conventional separate, compression of the signals of different RUs leads to significant performance gains. However, the approach therein was limited to the intra-cluster optimization of precoding and joint compression, hence leading to significant performance loss in the presence of mutually interfering clusters. This work proposes instead to perform the inter-cluster optimization of precoding and joint compression. Specifically, the problem of maximizing the weighted sum-rate maximization across multiple clusters is tackled by deriving an iterative algorithm that converges to a locally optimal point of the problem. From numerical results, it is confirmed that the proposed scheme significantly outperforms the existing approach based on intra-cluster optimization.

关键词： Cloud radio access networks (C-RANs) inter-cluster interference constrained fronthaul multivariate compression

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