Interference Control Scheme Research Articles

Self-Detecting Traffic Interference Control for Multi-Zone Services under 5G-Based Cellular Networks.

In this paper, we propose a multi-zone service control scheme to maximize the performance of each service zone when a large number of cellular service zones and Device-to-Device (D2D) service zones are composed into the 5G cellular network. This paper also improves performance of service zone by dividing traffic into real-time traffic and non-real-time traffic in order to minimize traffic interference. Real-time traffic and non-real-time traffic have a significant impact on communication performance. We propose a new self-detection traffic interference control technique to improve the Quality of Service (QoS) and throughput of D2D and Cellular-to-Device (C2D) communication in a cellular network, Self-detecting Traffic Interference Control Scheme (STICS). The proposed STICS mechanism distinguishes between short-term traffic congestion process and long-term traffic congestion process according to traffic characteristics to detect and control traffic. When the proposed scheme is applied to the 5G-based cellular network environment, it is expected that the traffic type will be efficiently classified by self-detecting the traffic according to the flow. Such classified traffic is less sensitive to communication between the D2D and C2D links, thereby reducing traffic overload. We evaluate the performance of the proposed scheme through simulation and show that the proposed scheme is more efficient than other comparison schemes.

Decentralized Slot-Ordered Cross Link Interference Control Scheme for Dynamic Time Division Duplexing (TDD) in 5G Cellular System

Dynamic time-division duplexing (TDD) allows for flexible resource allocation for the varying downlink (DL) and uplink (UL) traffic demands in the 5G cellular network. It becomes more useful when the number of active users is highly limited, especially for the small cells in a ultra-dense network. However, traffic imbalance between DL and UL in adjacent cells incurs crosslink interference (CLI), which may seriously reduce the system throughput. In order to deal with CLI induced by dynamic TDD, full or partial information on slot assignment and/or mutual interference must be shared among all cells for coordinating dynamic slot assignment throughout the system. In this paper, we propose the fully decentralized slot assignment policies that can reduce the CLI without resorting to side information shared among the cells. It is based a bi-directional slot-ordered scheduling scheme in each subframe, which exploits implicit location-dependent information such as signal-to-interference-plus-noise ratio (SINR) and/or three-dimensional spatial angle for all UEs in each cell under a full-dimension multi-input and multi-output (FD-MIMO) operation. Our system-level performance evaluation in 5G system scenario has shown that the proposed approach can maintain total interference almost constant even subject to the CLI. Furthermore, it achieves the average system throughput as much as 95% and 91% of the performance that can be achieved by a centralized greedy search for DL and UL, respectively, without much compromising the lower 5% system throughput.

Downlink Interference Control of LAA-LTE for Coexistence With Asymmetric Hidden Wi-Fi APs

To confront the increasing mobile traffic demand and the scarcity of the licensed band, 3GPP has standardized a new type of LTE, called License Assisted Access (LAA) LTE (LAA-LTE), which aggregates licensed bands with unlicensed bands. Since the conventional Wi-Fi devices employ −62 dBm clear channel assessment threshold to LAA-LTE's signals, the appearance of LAA-LTE in the unlicensed band leads to a new phenomenon, asymmetric hidden terminal problem , which severely degrades the throughput and delay performance of LAA-LTE as well as Wi-Fi. We propose a downlink interference control scheme for an LAA-LTE eNB to prevent the asymmetric hidden Wi-Fi APs nearby from recklessly transmitting and thereby interfering the eNB's transmission. Specifically, we analyze the distortion of Wi-Fi's signals received at LAA-LTE and LAA-LTE's signals received at Wi-Fi due to the difference of physical-layer parameters between LAA-LTE and Wi-Fi. Based on this analysis, we develop an AP suppression and power control technique to control incoming and outgoing interference of the LAA-LTE eNB. Extensive simulations confirm that the proposed scheme improves the throughput and delay performance of LAA-LTE while maintaining or even improving the performance of Wi-Fi.

Downlink Interference Control in Heterogeneous Cellular Networks: Macroscopic and Microscopic Control

In heterogeneous cellular networks that consist of macrocells and small cells, efficient interference management schemes between macrocells and small cells are crucial for overall system performance. To mitigate intercell interference, we propose macroscopic and microscopic interference control schemes. First, as a macroscopic interference control scheme, we propose a dynamic coordinated silencing. This scheme dynamically controls optimal bandwidth silencing between macrocells and small cells. It is carried out from a system quality of service (QoS) perspective on a long-term basis. Second, as a microscopic interference control scheme, we propose a user QoS-based rate splitting. This scheme controls optimal transmit power and rate for the split messages of scheduled users. It works as the complements of the proposed macroscopic control and is carried out on a short-term basis. The performance evaluations with ten small-cell deployment in each macrocell confirm that the proposed macroscopic control offers $28\%$ and $8\%$ enhanced cell-average spectral efficiency when it is compared with soft fractional reuse control and static silencing control, respectively, and $55\%$ and $23\%$ enhanced cell-edge spectral efficiency when it is compared to partitioning-based control and static silencing control, respectively. Further, it is shown that the proposed microscopic control can additionally enhance cell-edge spectral efficiency by preventing users from being interfered in dead-zone area.

Blind Interference Alignment in Two-Cell Z Interference MIMO Channel

This paper proposes a blind interference alignment (BIA) scheme in two-cell Z interference multiple-input multiple-output channel where the cell edge user equipment (UE) of the first cell is interfered by the base station of the second cell during downlink transmissions, while the UE of the second cell is free from inter-cell interference. By employing the reconfigurable antennas at receivers, the transmit strategy of the proposed scheme is designed. The achievable degree of freedom (DoF), the achievable rates, and the bit error rate performance of the proposed BIA scheme are analyzed. Simulation results show that the achievable DoF and the throughput of the proposed scheme are improved compared with conventional interference control scheme. Furthermore, in the proposed BIA scheme, all UEs can achieve a good diversity gain to combat fading.

Distributed uplink interference control based on resource splitting in heterogeneous cellular networks

Heterogeneous cellular networks that consist of macrocells and small cells can offer significant capacity gain by utilizing the resources of the small cells. However, for this purpose, the interference between the macrocells and the small cells should be carefully managed. In this paper, we propose two types of uplink inter-cell interference control schemes: handover-assisted bandwidth-splitting and quality-of-service (QoS)-aware power-splitting. The bandwidth-splitting interference control scheme is a win---win strategy that enhances the rates of both interfering user and interfered user via handover and frequency partitioning. On the other hand, the power-splitting interference control scheme is a yield-win strategy that enhances the rate of interfered user while reducing the rate of interfering user via message and power partitioning. Each scheme has its own operation region. The bandwidth-splitting scheme can be employed when the interfering user is located in the outer cell region having low signal-to-noise ratio (SNR), whereas the power-splitting scheme can be employed when the interfering user is located in the inner cell region having high SNR. We also propose an operational framework with low feedbacks and computational complexity. Simulation results show that the proposed controls significantly reduce interference while guaranteeing the target user QoS at best; therefore, they provide enhanced rate distribution, average ergodic rate and outage ratio under the typical target rate and range expansion bias, as compared to legacy interference control schemes.

Efficient Interference Control Technology for Vehicular Moving Networks

This paper proposes an efficient interference control scheme for vehicular moving networks. The features of the proposed scheme are as follows: radio resources are separated into two resource groups to avoid interference between the cellular and vehicle-to-vehicle (V2V) links; V2V links are able to share the same radio resources for an improvement in the resource efficiency; and vehicles can adaptively adjust their transmission power according to the interference among the V2V links (based on the distributed power control (DPC) scheme derived using the network utility maximization method). The DPC scheme, which is the main feature of the proposed scheme, can improve both the reliability and data rate of a V2V link. Simulation results show that the DPC scheme improves the average signal-to-interference-plus-noise ratio of V2V links by more than 4 dB, and the sum data rate of the V2V links by 15% and 137% compared with conventional schemes.

부 어레이 빔포밍을 활용하는 간섭 제어 기법 및 셀룰러 시스템에서의 성능 평가

늘어나는 트래픽 양을 감당하기 위한 방안 중 하나로, 기지국 간의 간섭을 줄여 데이터 전송 속도를 최대화 시키는 방식의 연구가 활발히 진행 중이다. 본 연구에서도 간섭 제어를 위해 안테나 부 어레이를 활용하는 빔포밍을 통하여 간섭을 제어하는 두 가지 기법을 제안한다. 첫 번째 방식은 수평 빔 회전방식으로써 세 종류의 좁은 빔 패턴을 만들고, 이 빔 패턴을 시간 축에서 회전시키면서 간섭을 제어하는 방식이다. 두 번째 방식은 사용자 별 부 어레이 빔포밍 방식으로써 전송받는 사용자 위치에 맞춰 빔포밍 행렬을 적용함으로써 여타 사용자에 대한 간섭을 최소화하는 방식이다. 제안하는 방식의 활용을 통해 셀 내에서 수신 신호 세기 증가 및 외부 셀로부터의 간섭 신호를 억제하는 효과를 얻을 수 있으며, 시뮬레이션을 통해 제안하는 방식들의 성능 이득을 정량적으로 평가하여 제시한다. To cope with an increasing amount of data traffic, research efforts are being made to maximize the data rate by reducing the interference between the transmission nodes. This paper also focuses on interference control schemes utilizing antenna sub-array beam-forming. The first scheme relies on horizontal beam rotation which utilizes three types of narrow beam patterns. Different beam patterns are applied to transmit signals in rotating fashion to control the interference. The second scheme is based on user-specific sub-array beamforming, which uses the precoding matrix based on users' location and controls the amount of interference in the multi-user environment. The performance of the proposed schemes is evaluated using the computer simulation to demonstrate the performance enhancement.

Cooperative Strategies for Wireless Relay Networks With Cochannel Interference Over Time-Correlated Fading Channels

Practical mobile communication systems suffer from time-variant channel fading and cochannel interference, both of which give rise to challenges concerning strategy design and performance analysis in wireless relay networks. Although these two aspects have attracted concerns in recent studies, most researchers still focused on dealing with a single problem and avoided intricate joint considerations. In this paper, we investigate the cooperative strategies for the communications of two cochannel pairs over time-correlated Rayleigh channels, and the system consists of a relay-assisted pair (Pair 1) along with a direct transmission pair (Pair 2). We begin with a theoretical evaluation on a conventional relay selection (RS) algorithm that maximizes outdated signal-to-interference-plus-noise ratio (M-SINR), and then develop a more sophisticated method that involves extra statistical and interference information based on the concept of minimizing outage probability (MOP). Closed-form outage probability expressions are derived for both pairs with each RS algorithm, and the MOP-type selection is confirmed to outperform M-SINR in robustness against channel fluctuation when the network operates on medium-to-high signal-to-noise ratio (SNR). Implementation issues of the RS methods are discussed to clarify their overhead and to support their practicability. Further, an interference control scheme is proposed to guarantee Pair 2 communication quality under either RS algorithm by disqualifying the relays that probably cause severe cochannel interference to Pair 2. The interference control mechanism is carried out via a novel threshold parameter e that represents the tolerance of outage performance degradation of Pair 2 resulting from interference. The closed-form analysis validates that the given e is rational for an arbitrary network scenario, and it can balance the two pairs' outage behavior under a proper configuration. We reveal the influence of factors such as average SNR, transmit rate, and network topology on system performance to make a comprehensive comparison between diverse cooperative strategies.

Interference Control for Cognitive Network with High Mobility

Interference control (IC) between the secondary system and the primary system is an important issue for underlay cognitive radio network (CRN). The secondary system should limit the interference power to primary system by adjusting its transmission power. Many relevant works have been done based on the assumption of the quasistatic channel which is not suitable for the fast time-varying fading channel; the performance of IC in underlay CRN will become worse when the channel varies fast. This paper studies the IC issue in high mobility environment. By considering the channel state information (CSI) outdatedness, a short frame structure scheme and a mean interference power constraint scheme are proposed to reduce the influence of CSI outdatedness on IC performance. Furthermore, by considering the channel estimation error, a spherical error region model based robust IC scheme is designed as well. The proposed IC schemes of the secondary system are converted to the power allocation problems, and then they are formulated to optimization problem whose objects are to maximize the capacity of the secondary system with the interference constraints. The above optimization problems are solved by the water-filling style method. The simulation results show that the proposed IC schemes can effectively control the interference power to the primary system.

Price-based interference control for two-tier femtocell networks

This paper presents a novel price-based interference control scheme for two-tier femtocell networks, aiming to limit the interference from femtocell users to macrocell base station (MBS). Assuming that the MBS protects itself by pricing the interference power from the femtocell users, the femtocell users set their transmission powers by competitively selecting the interference power fractions under the constraint of the total tolerable interference. The problem of femtocell users’ competitive interference occupation process is cast into a non-cooperative interference power purchase game, and the existence and uniqueness of the Nash equilibrium is proved. Then, a distributed interference power fraction iterative algorithm is developed to find the Nash equilibrium of the game, and the convergence analyses in both synchronous and asynchronous cases are presented. The distributed implementations are also shown. Simulation results show the convergence of the interference power fraction iterative algorithm and the effectiveness of the proposed interference control scheme.