Interference Reduction

In live and studio recordings unexpected sound events often lead to interferences in the signal. For non-stationary interferences, sound source separation techniques can be used to reduce the interference level in the recording. In this context, we present a novel approach combining the strengths of two algorithmic families: NMF and KAM. The recent KAM approach applies robust statistics on frames selected by a source-specific kernel to perform source separation. Based on semi-supervised NMF, we extend this approach in two ways. First, we locate the interference in the recording based on detected NMF activity. Second, we improve the kernel-based frame selection by incorporating an NMF-based estimate of the clean music signal. Further, we introduce a temporal context in the kernel, taking some musical structure into account. Our experiments show improved separation quality for our proposed method over a state-of-the-art approach for interference reduction.

In live and studio recordings unexpected sound events often lead to interferences in the signal. For non-stationary interferences, sound source separation techniques can be used to reduce the interference level in the recording. In this context, we present a novel approach combining the strengths of two algorithmic families: NMF and KAM. The recent KAM approach applies robust statistics on frames selected by a source-specific kernel to perform source separation. Based on semi-supervised NMF, we extend this approach in two ways. First, we locate the interference in the recording based on detected NMF activity. Second, we improve the kernel-based frame selection by incorporating an NMF-based estimate of the clean music signal. Further, we introduce a temporal context in the kernel, taking some musical structure into account. Our experiments show improved separation quality for our proposed method over a state-of-the-art approach for interference reduction.

The interference imposes a significant negative impact on the performance of wireless networks. With the continuous deployment of larger and more sophisticated wireless networks, reducing interference in such networks is quickly being focused upon as a problem in today's world. In this paper we analyze the interference reduction problem from a graph theoretical viewpoint. A graph coloring methods are exploited to model the interference reduction problem. However, additional constraints to graph coloring scenarios that account for various networking conditions result in additional complexity to standard graph coloring. This paper reviews a variety of algorithmic solutions for specific network topologies.

There are still a lot of open questions in the field of MANETs and sensor networks. If a topology incurs a large interference, either many communication signals sent by nodes will collide, or the network may experience a serious delay at delivering the data for some nodes, and even consume more energy. So, we reach to the conclusion that interference imposes a potential negative impact on the performance of wireless networks. In the last few years, researchers actively explored topology control approaches for such networks. The motivation of topology control (TC) is to maintain the connectivity of the network, reduce the node degree and thereby reduce the interference, and reduce power consumption in the sensor nodes. Some literatures have pointed out that a node can interfere with another node even if it is beyond its communication range. To improve the network performance, designing topology control algorithms with consideration of interference is imminent and necessary. Since, it leads to fewer collisions and packet retransmissions, which indirectly reduces the power consumption and extends the lifetime of the network. In this thesis, we propose a new interference-aware connected dominating set-based topology construction algorithm, namely, IACDS algorithm, a simple, distributed, interference-aware and energy-efficient topology construction mechanism that finds a sub-optimal Connected Dominating Set (CDS) to turn unnecessary nodes off while keeping the network connected and providing complete communication coverage with minimum interference. IACDS algorithm utilizes a weighted (distance-energy-interference)-based metric that permits the network operator to trade off the lengths of the branches (distance) for the robustness and durability of the topology (energy and interference).

By increasing the number of antennas, the size and weight of massive Multiple Input Multiple Output (MIMO) become much larger and heavier, respectively. To deal with these problems, the 3GPP standardization group captured the multipanel in New Radio communications. Channel estimation is needed for accurate uplink signal recovery and downlink precoding of massive MIMO. Due to the use of hybrid structure and the nonuniform distribution of the antenna arrays, the conventional channel estimation methods cannot be used in multipanel massive MIMO. In this paper, we propose the channel estimation for the millimeter-wave multipanel MIMO systems in multiuser environments, in which the channel estimation problem is transformed to an angular domain block sparse signal recovery problem. In the following, we solve the obtained sparse model using the proposed generalized block orthogonal matching pursuit method. Also, the proper pilot sequence is designed in the proposed method. Finally, we check...

Recently, a promising network topology for wireless networks, called the Hierarchical Layer Graph (HL graph), has been introduced and analyzed by Meyer auf der Heide et al. 2004. This graph can be used as a topology for wireless networks with variable transmission ranges. In this paper we present a distributed, localized and resource-efficient algorithm for constructing this graph. The performance of the HL graph depends on the domination radius and the publication radius, which affect the amount of interference in the network. Worst case analysis shows a tradeoff between these parameters. We investigate the performance on randomly distributed vertex sets and show that the restrictions on these parameters are not so tight using realistic settings. Here, we present the results of our extensive experimental evaluation, measuring congestion, dilation and energy. Congestion includes the load that is induced by interfering edges. We distinguish between congestion and realistic congestion where we take also the signal-to-interference ratio into account. Our extensive experiments show that the HL graph contains energy-efficient paths as well as paths with a few number of hops while preserving a low congestion.

Large-scale, self-organizing wireless sensor and mesh network deployments are being driven by recent technological developments such as The Internet of Things (IoT), Smart Grids and Smart Environment applications. Efficient use of the limited energy resources of wireless sensor network (WSN) nodes is critically important to support these advances, and application of topology control methods will have a profound impact on energy efficiency and hence battery lifetime. In this survey, we focus on the energy efficiency issue and present a comprehensive study of topology control techniques for extending the lifetime of battery powered WSNs. First, we review the significant topology control algorithms to provide insights into how energy efficiency is achieved by design. Further, these algorithms are classified according to the energy conservation approach they adopt, and evaluated by the trade-offs they offer to aid designers in selecting a technique that best suits their applications. Since the concept of "network lifetime" is widely used for assessing the algorithms' performance, we highlight various definitions of the term and discuss their merits and drawbacks. Recently, there has been growing interest in algorithms for non-planar topologies such as deployments in underwater environments or multi-level buildings. For this reason, we also include a detailed discussion of topology control algorithms that work efficiently in three dimensions. Based on the outcomes of our review, we identify a number of open research issues for achieving energy efficiency through topology control.

One of the critical constraints for lifetime and operability of sensor networks is the limited amount of available energy. Reducing the interference is one of the important positive steps towards this as high interference number increases the probability of packet loss and hence forces the sender node to retransmit the packets resulting in more energy consumption. Minimum Interference Strong Bidirectional Topology (MISBT) problem is to assign transmit power to each sensor in a sensor network such that the maximum/average node interference of a sensor is minimised subject to the constraint that the induced topology containing bidirectional links only is strongly connected. In this paper we propose two new models for measuring the interference, namely the MAX model and SUM model. We present algorithms for minimising maximum and average node interference under these models. The average interference obtained by our algorithms for MAX and SUM models is at most twice the optimal. The simulation results show that the total power consumptions by the solution produced by our algorithm under the SUM model is less than the solution produced by the existing algorithm under the OR model. Furthermore, our algorithms under different models are 2-approximation algorithms for the average receiver-centric interference as well.

Energy consumption is one of the most important performance metrics for wireless ad hoc networks because it directly relates to the operational lifetime of the network. Based on this thought, in this article we will establish an ad-hoc network where the power consumption during transmission can be controlled. To minimize the total energy consumption, we have adopted a simple network layer/routing model that serves as a benchmark for performance evaluation. Herein we have worked with the mesh topology, and each nodes of the network are substituted using directional antenna. The four directional antennas are used to represent each node. When a node needs to send information to others it only enables its particular sector or sectors through which it is connected to those nodes. We have also replaced the nodes in the network with sectors and found that the total energy consumed by the network is much less. We devised an algorithm to find the average dominating set without varying the radius of the network. Also, we found the minimum dominating set within a graph by varying the number of nodes only i.e. the density of the graphs. After establishing our own set of algorithm to find the minimum dominating set in a network, it is compared with Dai & Wu's Algorithm .We believe by using such a generic model, with special added advantages, we will succeed in meeting our goal.

Topology control is a technique used in wireless sensor networks to maximize energy efficiency and network lifetime. In previous literature, many tree based techniques have been proposed to save energy and increase the network lifetime. In tree based algorithms, the most promising solution is the formation of a network backbone, which serves on behalf of rest of the nodes in the network and therefore leading towards Connected Dominating Set (CDS) formulation. However, one imminent problem with all tree based solution is a compromise on network reliability. Therefore, to address reliability issues in tree based solutions, in this paper, we propose Poly3 which maintains cliques of size three in order to achieve network reliability on top of the CDS algorithm. This makes the network more robust to link removal. Our empirical and mathematical analysis reveals that Poly3 provides better reliability than algorithms of the same kind.

The interference imposes a significant negative impact on the performance of wireless network. With the continuous development of larger and more sophisticated wireless networks, reducing interference in such networks is quickly being focused upon as a problem in today's world. In this paper we analyze the inference reduction problem from a graph theoretical view point. A graph colouring provides various networking conditions, results and variety of algorithms solutions and network topologies.

The problem of reducing interference in wireless networks is becoming increasingly important with the continuous deployment of larger and more sophisticated wireless networks. In this report we analyze the interference problem from a graph theoretical viewpoint. The interference reduction problem is modeled as a graph coloring problem. However, additional constraints to graph coloring scenarios that account for various networking conditions result in additional complexity to standard graph coloring. This paper discusses a variety of algorithmic solutions for specific network topologies and makes recommendations for implementation.

Topology control is a well-known strategy to save energy and extend the lifetime of wireless sensor networks. This paper introduces the A3 (a tree) algorithm, a simple, distributed, and energy-efficient topology construction mechanism that finds a sub-optimal Connected Dominating Set (CDS) to turn unnecessary nodes off while keeping the network connected and providing complete communication coverage. A3 utilizes a weighted distance-energy-based metric that permits the network operator to trade off the lengths of the branches (distance) for the robustness and durability of the tree (energy). Comparisons with other well-known topology construction mechanisms show the superiority of the proposed scheme in terms of the number of active nodes and energy efficiency. Simulation experiments show that to achieve complete communication coverage, A3 needs only 6% and 41% of the nodes active in dense and sparse scenarios, versus 8% and 43% and 5% and 43% of the EECDS and CDS-Rule-K algorithms, respectively. More importantly, the proposed protocol presents a low linearly bounded worst-case amount of messages per node that limits the overhead and the energy usage compared to a non-linear increase of the EECDS and CDS-Rule-K algorithms.

Abstract The communication topology plays a key rule in the overall network performance. Topology management via power control has been addressed by many researchers to attain better utilization of available resources by reducing the complexity of the network topology. Energy conservation in these protocols is mainly achieved by utilizing lower transmission power levels. Like other types of wireless ad hoc networks, this feature makes their applicability in sensor networks equally attractive.

There are still a lot of open questions in the field of mobile ad hoc networks (MANETs) and sensor networks. If a topology incurs a large interference, either many communication signals sent by nodes will collide, or the network may experience a serious delay at delivering the data for some nodes, and even consume more energy. So, we reach the conclusion that interference imposes a potential negative impact on the performance of wireless networks. In the last few years, researchers actively explored topology control approaches for such networks. The motivation of topology control (TC) is to maintain the connectivity of the network, reduce the node degree and thereby reduce the interference, and reduce power consumption in the sensor nodes. Some literatures have pointed out that a node can interfere with another node even if it is beyond its communication range. To improve the network performance, designing topology control algorithms with consideration of interference is imminent and necessary. Since, it leads to fewer collisions and packet retransmissions, which indirectly reduces the power consumption and extends the lifetime of the network. In this paper, we propose a new interference-aware connected dominating set-based (IACDS) topology construction algorithm, namely, IACDS algorithm, a simple, distributed, interference-aware and energy-efficient topology construction mechanism that finds a sub-optimal connected dominating set (CDS) to turn unnecessary nodes off while keeping the network connected and providing complete communication coverage with minimum interference. IACDS algorithm utilizes a weighted distance-energy-interference-based metric that permits the network operator to trade off the lengths of the branches (distance) for the robustness and durability of the topology (energy and interference).

considerable amount of energy is dissipated due to interference. Therefore,
interference is one of the major challenges in wireless ad hoc and sensor networks.
It alters or disrupts a message as it is being transmitted along a channel
between source and destination. Since the messages are disrupted when the
interference occurs, they have to be detected and the interfered messages have
to be retransmitted. In this paper, we propose central and distributed heuristic
algorithms for reducing average interference in receiver-centric interference model.
In the literature, Minimum Spanning Tree (MST) algorithm is generally used
through the interference coverage graph directly or indirectly in order to generate
minimum average interference topology. Our algorithm, Dynamic Average
Interference (DAI), however generates lower average interference as well as more
sparse topology than MST. We realized that if the transmission ranges of nodes
are taken into consideration at each stage of topology control algorithm, the
interference of links are changed dynamically. This interference changing enables
up to 22 % more energy saving than MST algorithm. Thus, DAI provides energy
saving by reducing the interference as far as possible in generated topology.