Wireless Measurement Framework to Survey an Area with Required Communication Quality

In this paper, the convergence time of federated learning (FL), when deployed over a realistic wireless network, is studied. In particular, a wireless network is considered in which wireless users transmit their local FL models (trained using their locally collected data) to a base station (BS). The BS, acting as a central controller, generates a global FL model using the received local FL models and broadcasts it back to all users. Due to the limited number of resource blocks (RBs) in a wireless network, only a subset of users can be selected to transmit their local FL model parameters to the BS at each learning step. Moreover, since each user has unique training data samples, the BS prefers to include all local user FL models to generate a converged global FL model. Hence, the FL training loss and convergence time will be significantly affected by the user selection scheme. Therefore, it is necessary to design an appropriate user selection scheme that can select the users who can contribute toward improving the FL convergence speed more frequently. This joint learning, wireless resource allocation, and user selection problem is formulated as an optimization problem whose goal is to minimize the FL convergence time and the FL training loss. To solve this problem, a probabilistic user selection scheme is proposed such that the BS is connected to the users whose local FL models have significant effects on the global FL model with high probabilities. Given the user selection policy, the uplink RB allocation can be determined. To further reduce the FL convergence time, artificial neural networks (ANNs) are used to estimate the local FL models of the users that are not allocated any RBs for local FL model transmission at each given learning step, which enables the BS to improve the global model, the FL convergence speed, and the training loss. Simulation results show that the proposed approach can reduce the FL convergence time by up to 56% and improve the accuracy of identifying handwritten digits by up to 3%, compared to a standard FL algorithm.

The paper explores the quality of communication in wireless networks and the assessment of the quality of communication for the main parameters of indoor and outdoor use. The analysis of the influence of the surrounding radio waves of wireless communication networks was carried out on different types of medium. The propagation of radio waves in the room and in the open air was compared. In addition, there is some measurements of signal power passing through different obstacles.

In a wireless communication system, a cooperative communication technique is a communication method for improving performance. In the conventional scheme, when a destination user is located in the cell boundary, one base station communicates with a destination user. At a same time, a destination user communicates with other base stations which cooperate with base station. If a distance between a base station and a destination user is far, the quality of communication is degraded by the effect of channel attenuation. Therefore, this paper proposes an enhanced cooperative transmission scheme using the orthogonal frequency multiplexing in the wireless communication system. The proposed scheme uses extra relays between a base station and a destination user. When the channel state of a destination user is bad, other base stations are used. In order to obtain better performance than the conventional scheme, the cooperative decode and forward (DF), and space time cyclic delay diversity (STCDD) and cyclic delay diversity (CDD) are applied in the extra relays. In simulation results, the proposed scheme has higher error and throughput performances than the conventional scheme for obtaining diversity gain when the used modulation scheme is increased. Also, the proposed scheme which uses cooperative DF has slightly better error and throughput performances than the proposed scheme which uses cooperative STCDD and CDD due to less error propagations and resultant higher diversity gain.

We consider the problem of resource allocation for data transfer between the base station and the users within a cell of a wireless telecommunication network with infinite data queues for each user. The aim is to study the tradeoff between the conflicting objectives of maximizing the system throughput and the quality of service (QoS) to an individual user. Using a policy improvement approach based on Markov decision processes, we develop an intuitive and easy-to-implement index policy. We also demonstrate its superior performance over the existing proportional fair metric algorithm through simulation experiments.

Wireless network virtualization is an emerging technology that logically divides a wireless network element, such as a base station (BS), into multiple slices with each slice serving as a standalone virtual BS. In such a way, one physical mobile wireless network can be partitioned into multiple virtual networks each operating as an independent wireless network. Wireless virtual networks, as composed of these virtual BSs, need to provide quality of service (QoS) to mobile end user services. Key QoS parameters include buffer queue length, network delay and effective bandwidth, in particular their upper bound forms. This paper presents a QoS model for such a wireless virtual network addressing these parameters. This QoS model considers resources of both physical nodes and virtual nodes and provides a realistic modelling of the delay and bandwidth behaviours of wireless virtual networks. Network calculus (NC), which usually provides finer insight into a system, is utilized to fulfil the modelling task. The numerical results have shown the effectiveness of the proposed model. The model is useful for both off-line network planning and online network admission control.

As the demands of coverage and bandwidth increases day by day, the power consumption in wireless network becomes serious issue that needs optimization. Mainly, most of the power in wireless network is consumed in the base stations as transmission power. Reducing the transmission power may affect the QoS at the network. In practice, the network base stations load varies according to the traffic density in the region. Therefore, at low traffic density, most of the base stations are operating on partial load. This fact motivates the concept of blossoming and withering of the small base stations to utilize the full capacity of the operating base stations, and preserving more power by withering the rest of base stations. The rate of change of the network traffic density is not flat throughout the day or week. To accommodate the change of the traffic pattern and optimize the network blossomed and withered small base stations, fuzzy logic inference system is proposed. The proposed fuzzy system measures the traffic of the system and its rate of change and accordingly estimates the percentages of the small base stations to blossom and the delay required to avoid the ping-pong phenomena in the base stations. For the proposed fuzzy to keep track of the current status of the network, the percentage of blossomed small base stations is fed back as input. The results show that the capacity of the network can be maintained during different traffic loads while reducing the total power of transmission by withering some small base stations during low traffic load. The proposed system reserved up to 36.37% of the transmission power.

This paper presents an initial study on how to model user mobility in a wireless cellular network scenario. The model provides realistic patterns of movement between a number of locations. The aforementioned mobility model is built upon to introduce a base station (BS) energy efficient power state control algorithm (EESC) that is able to provide significant energy savings for the simulated scenario. Erratic subsequent on and off BS behavior is avoided by referring to an average loading curve, generated for each BS during a learning period, when making decisions. Moreover, BSs are turned off only when the users can be handed off to nearby cells with a predefined maximum allowed predicted loss in data rate. The resulting system is able to deliver an energy consumption reduction between 36% and 11% over an always on benchmark for the simulated scenarios. There is negligible loss in terms of achieved data rate per user.

With enormous growth in the telecommunication industry, energy efficiency has become a critical issue. Base stations and the core network account for a large amount of energy consumption today. Traditional energy saving techniques switch some base stations off completely during light loads to save energy. This creates problems for the backhaul network and also for quickly returning to full capacity when demand increases. In this paper, we propose novel cell zooming techniques to reduce energy consumption at base stations. With cell zooming, base stations dynamically adjust their coverage radius and hence their transmit powers based on user locations. The transmit power is set to the minimum required level depending on user locations, signal to interference and noise ratio (SINR) and quality of service (QoS) requirements of the users. Base stations are never completely switched off. Our simulations show that the proposed cell zooming algorithm reduces the energy consumption of base stations by up to 40% compared to traditional static-coverage-area base stations without compromising on the QoS requirements of any user in the cell.

Many handover algorithms are proposed in the literature. However, to make a better handover and keep the QoS in wireless networks is very difficult. In this paper, we propose a new handover system based on fuzzy logic. The proposed system uses 3 parameters for handoff decision: the change of signal strength of the present Base Station (BS), signal strength from the neighbor BS, and the distance between Mobile Station (MS) and BS. The performance evaluation via simulations shows that proposed system can avoid ping-pong effect and has a good handover decision.

Wireless access networks like wireless LANs have been diffused widely. However, as mobile devices and applications increase and become diverse, more devices with various packet generation rates are expected to access such wireless networks. In this paper, in wireless access networks in which wireless stations (STAs) and a base station (BS) communicate directly in a multichannel environment, we propose novel channel selection control. This proposal adaptively switches the channel, on which each of the STAs is operating, to assign sufficient communication bandwidth to all of the STAs and the BS regardless of their packet generation rates.

Public transportation is vital in everyday life. As a consequence, the increasing need for intelligent surveillance systems over public transportation provides promising areas for wireless vehicular communication research for in-tunnel applications. This paper particularly emphasizes on tunnel implementation regarding to a prototype surveillance system on railway environments based on autonomous, smart monitoring devices that capture data only upon the occurrence of an incident, potentially dangerous for the passengers (like an explosion blast or the triggering of the fire detector). In this paper an attempt has been made to evaluate the performance of wireless vehicular communication inside a challenging tunnel environment after an emergency event. Due to the fact that extreme tunnel conditions (i.e. blind spots, intersymbol interference, NLOS) can cause major wireless network propagation failure, we develop a wireless hybrid network architecture consisted of IEEE 802.11b/g/e and IEEE 802.16e protocols. Furthermore this network was implemented in order to transmit the captured data from the monitoring devices of the train coaches to the Base Stations that are placed towards the metro stations. Finally, we use the OMNeT++ simulator tool for creating a simulation environment of the vehicular wireless network in order to compare the results with the experimental measurements.

Network protocols in cellular wireless data networks must update routes as a mobile host moves between cells. These routing updates combined with some associated state changes are called handoffs. Most current handoff schemes in wireless networks result in data loss or large variations in packet delivery times. Unfortunately, many applications, such as real-time multimedia applications and reliable transport protocols, adapt to long term estimates of end-to-end delay and loss. Violations and rapid fluctuations of these estimates caused by handoff processing often result in degraded performance. For example, loss during handoff adversely affects TCP performance [4], and high packet loss and variable delays result in poor real-time multimedia performance. In this paper, we describe a multicast-based protocol that eliminates data loss and incurs negligible delays during a handoff. The basic technique of the algorithm is to anticipate a handoff using wireless network information in the form of received signal strengths and to multicast data destined for the mobile host to nearby base stations in advance. This routing, combined with intelligent buffering techniques at the base stations, enables very rapid routing updates and eliminates data loss without the use of explicit data forwarding. We have implemented this protocol using IP Multicast and Mobile IP-like routing. In our implementation, handoffs typically take between 8 and 15 ms to complete and result in no data loss.

Introduction It is envisioned that the capacity demand in fifth generation (5G) wireless networks will increase by 1000 times before the year 2020, and this huge demand will be fueled by high-definition video and content streaming applications, which not only consume immense wireless bandwidth but also have stringent real-time quality of service (QoS) requirements. Small-cell dense wireless networks are regarded as a key candidate 5G technology to meet such aggressive demand. By dense deployment of small-cell base stations (BSs), the network becomes closer to mobile users, and thus the spectral efficiency per unit area can be significantly improved. Moreover, relay stations (RSs) without wired backhaul can also be deployed to enhance the coverage area and provide signal-to-noise ratio (SNR) gain. While there are many potential opportunities associated with dense wireless networks, the potential spectrum efficiency gain they can provide is significantly limited by increasingly severe interference due to the densification of BSs. There are several common schemes to mitigate interference. In the strong-interference case, channel orthogonalization, such as frequency division multiple access (FDMA) or time division multiple access (TDMA), is used to avoid interference [1], and advanced schemes, such as interference alignment (IA) [2, 3] and interference coordination [4, 5], have been proposed to increase the spectral efficiency of interference channels by jointly mitigating the interference using shared channel state information (CSI). However, these approaches may lead to inefficient use of channel resources because the transmitters do not share payload information and therefore are not fully cooperative. To improve the spectrum efficiency further, coordinated multipoint (CoMP) transmission has been proposed as one of the most important core technologies for Long Term Evolution-Advanced (LTE-A) and future 5G wireless networks [6]. By sharing both CSI and payload data among the BSs concerned, CoMP transmission can transform the wireless network from an unfavorable interference topology to a favorable broadcast topology, where the interference can be mitigated much more efficiently. However, the conventional CoMP scheme is quite costly because it requires a high-capacity backhaul for payload exchange between the BSs, and this poses a huge challenge for practical applications of CoMP, especially for small-cell dense wireless networks.

A wireless network gives flexibility to the user in terms of mobility that attracts the user to use wireless communication more. The video communication in the wireless network experiences Quality of Services (QoS) and Quality of Experience (QoE) issues due to network dynamics. The parameters, such as node mobility, routing protocols, and distance between the nodes, play a major role in the quality of video communication. Scalable Video Coding (SVC) is an extension to H.264 Advanced Video Coding (AVC), allows partial removal of layers, and generates a valid adapted bit-stream. This adaptation feature enables the streaming of video data over a wireless network to meet the availability of the resources. The video adaptation is a dynamic process and requires prior knowledge to decide the adaptation parameter for extraction of the video levels. This research work aims at building the adaptation parameters that are required by the adaptation engines, such as Media Aware Network Elements (MANE), to perform adaptation on-the-fly. The prior knowledge improves the performances of the adaptation engines and gives the improved quality of the video communication. The unique feature of this work is that, here, we used an experimental evaluation method to identify the video levels that are suitable for a given network condition. In this paper, we estimated the adaptation parameters for streaming scalable video over the wireless network using the experimental method. The adaptation parameters are derived using node mobility, link bandwidth, and motion level of video sequences as deciding parameters. The experimentation is carried on the OMNeT++ tool, and Joint Scalable Video Module (JSVM) is used to encode and decode the scalable video data.

Most of mobile nodes and wireless devices are equipped with 4G/LTE cellular connections and WiFi short range connections. Since these nodes/devices use cellular connections to access to the mobile core network at the same time, many of them cannot establish the cellular connections due to the limited wireless resources of the cellular base stations so that data messages cannot be disseminated from a source node to those nodes.The information dissemination schemes which accommodate these nodes for the base stations and utilize the wireless multi-hop communication have been proposed so far. In this paper, we propose an information dissemination scheme which uses autonomous clustering and epidemic routing, and it provides lower mobile core network load in wireless networks. The proposed scheme accommodates the number of mobile nodes which access to the base stations to reduce the mobile core network load and disseminates the data messages to them. The nodes which received the information messages through the mobile core network forward them to nearby nodes in a wireless multi-hop fashion. In addition, they are forwarded by epidemic routing for nodes which cannot receive them even in a wireless multi-hop fashion. Finally, we evaluate the proposed information dissemination scheme through simulation experiments and confirm the higher information dissemination rate with low mobile core network load in comparison with the existing scheme.