Dynamic Resource Allocation for 3-D Sidelink Communication in Unlicensed Spectrum

Exponentially growing demand for mobile data is pushing the existing mobile networks to the limit. In addition to offloading traffic onto WiFi access points (APs), dual-band femtocells (DBFs) that can simultaneously access both the licensed and unlicensed bands have been proposed for cellular networks to further exploit the unlicensed spectrum. However, the coexistence between DBFs and WiFi in the unlicensed spectrum is not without difficulty, given the potentially severe co- channel interference. In this paper, we first derive the probability of coverage overlap between DBF and WiFi APs by modelling the network nodes using a spatial bivariate Poisson point process, and then propose a novel framework for DBFs to effectively coexist with WiFi APs in the unlicensed spectrum considering various possibilities of coverage overlap between them. The performance of the proposed framework in terms of DBF channel occupancy in the unlicensed band is evaluated through both theoretical analysis and simulations.

Wi-Fi networks are becoming more and more ubiquitous and represent a substantial source of energy consumption around the globe, mainly when it comes to Access Points (APs). There has been some work done on the characterization of the power consumption of Wi-Fi APs and network interface cards (NICs), and the power usage of these devices under different configurations and standards but mostly using legacy standards. A detailed AP power consumption analysis, exploring the whole set of degrees of freedom and capabilities of these devices is lacking in the state of the art. In this paper, we present a thorough power consumption analysis, covering the configuration options available in enterprise Wi-Fi APs from the three major vendors on the market. The goal is to understand how the power consumption of an AP varies with the different configurations, and provide insights on the parameters that significantly affect the AP power consumption. The obtained experimental results confirm previous state-of-the-art conclusions but contradict some of the studies and results found in the literature, while updating results and conclusions taken in the past to the most recent standards, configurations, and data rates available today. The analysis provided herein is a valuable source of information for deriving new AP power consumption models and designing energy-efficient Wi-Fi networks.

Recent IT technology trends are confronted with a new technological phenomenon. It is the intersection of technology and liberal arts. That is, IT convergence. Although the convergence trends will keep going in the future, there is the Internet of Things which are a new priming to accelerate these trends. A multitude of IoT devices will transmit various information through Internet, and the main channel of information flows will be a Wi-Fi networks. However, current Wi-Fi technology isn’t prepared to accommodate these data yet. Therefore, we propose the Efficient Data Forwarding Scheme (EDFS) to solve these problems. The proposed EDFS assigns a proper transmission opportunity (TXOP) to the IoT devices for supporting efficient data transmission. In the EDFA, Wi-Fi AP (Access Point) gives a calculated or pre-defined TXOP, which is suitable for the data transmission attributes of IoT device. Due to the fact that the data transmission feature of IoT devices isn’t the real-time traffic in the most cases. Based on the EDFA, a Wi-Fi AP can not only assign an efficient TXOP to a device, but also support various IoT device requirements within the Wi-Fi hotspot. We compared it with legacy Wi-Fi transmission scheme to prove the outperforming results by using the OPNet simulator.Keywords: Data Forwarding, Internet of Things, TXOP, Wi-Fi

Performance analysis for MU-MIMO enabled LTE-U networks coexisting with D2D and WiFi network

In view of the fact that the limited wireless resources and the asymmetric traffic between uplink and downlink in the trunking communication system based on TD-SCDMA network, a design scheme of dynamic resource allocation (DCA) is given. DCA is a very effective technology to solve those problems and enhance the utilization of resource. Based on the characteristics of the trunking communication system, we combine with the DCA algorithms of TD-SCDMA network in this paper, and give an optimal DCA strategy for the truking communication system in TD-SCDMA network. Finally, the simulation result shows the DCA strategy markedly improve the system performance and gain higher resource utilization.

Orthogonal frequency division multiple access (OFDMA) is one of the critical features adopted in IEEE 802.11ax, where multiple stations can simultaneously access the wireless channel. Although appropriate sub-channel allocation is crucial to improving channel efficiency, the allocation method is vendor specific, since there is no central controller in the Wi-Fi network. In this chapter, we propose a utility-based dynamic resource allocation (UDRA) scheme for orthogonal frequency division multiple access resource management in IEEE 802.11ax WLANs. In UDRA, each access point (AP) obtains neighbor information using a newly proposed modified clear-to-send (M-CTS) frame by overhearing stations in an area overlapping with the other APs’ signal area. After that, we formulate the network-wise utility maximization problem, which considers both throughput and fairness, to determine which sub-channels should be allocated to which stations. Furthermore, we adopt a genetic algorithm to solve the derived optimization problem since the problem is known to be NP-hard. We map the proposed scheme, UDRA, onto a terminology of genetic algorithm. Extensive simulation results demonstrate that UDRA can guarantee comparable throughput to exhaustive search while preserving improved fairness with significantly reduced computing time.

As a result of the drastic increase in the number of mobile device users, there is considerable public debate about possible health hazards especially due to base stations and Wi-Fi access points. For this reason, in this study the effects of the number of users in a base station and wireless fidelity (Wi-Fi) access point on electric field strength (E) levels were investigated using real-time measurements. Two-stage E measurements were performed on Ondokuz Mayıs University's (OMU) Kurupelit Campus with a PMM-8053 and SRM-3006 electromagnetic field (EMF) meter. In the first stage, 24-h measurements were performed with PMM-8053 at the location where the maximum E was measured and from which the busiest times of the day were then determined. The relationship among band selective E values was assessed using the number of users per minute provided by three cellular system operators for the location. Upper and lower bounds of E according to the number of users were calculated, and then an empirical model that helps calculate the E of medium with 86% accuracy was proposed. In the second stage, the effect of the number of users in a Wi-Fi access point on E level was investigated. For this purpose, the measurement environment was set as including one Wi-Fi access point with needed measurement devices. The number of users was increased as per user per minute. The number of users was validated with the data obtained from OMU IT Department. Using the measurement result, a model with a 96% accuracy between the E value in the environment and the number of users accessing the Wi-Fi system is proposed. With the use of these models, E level in the medium can be determined without using any EMF meters, thus precautions can be taken to stay within regulatory limits.

We leverage stochastic geometry to characterize key performance metrics for neighboring Wi-Fi and LTE networks in unlicensed spectrum. Our analysis focuses on a single unlicensed frequency band, where the locations for the Wi-Fi access points (APs) and LTE eNodeBs (eNBs) are modeled as two independent homogeneous Poisson point processes. Three LTE coexistence mechanisms are investigated: (1) LTE with continuous transmission and no protocol modifications; (2) LTE with discontinuous transmission; and (3) LTE with listen-before-talk (LBT) and random back-off (BO). For each scenario, we have derived the medium access probability (MAP), the signal-to-interference-plus-noise ratio (SINR) coverage probability, the density of successful transmissions (DST), and the rate coverage probability for both Wi-Fi and LTE. Compared to the baseline scenario where one Wi-Fi network coexists with an additional Wi-Fi network, our results show that Wi-Fi performance is severely degraded when LTE transmits continuously. However, LTE is able to improve the DST and rate coverage probability of Wi-Fi while maintaining acceptable data rate performance when it adopts one or more of the following coexistence features: a shorter transmission duty cycle, lower channel access priority, or more sensitive clear channel assessment (CCA) thresholds.

Assuring the required quality of service, despite the growing volume and variety of Internet of Things (IoT) traffic, has remained an immense challenge in the popular WiFi networks. The IoT devices using short TCP flows often attain very different levels of service due to the complicated interactions between the transport layer protocol and the shared dynamic wireless medium. We develop in this paper a novel queue management policy by using a transient model to capture the interactions of IoT (short TCP) flows over traditional traffic in WiFi networks. Based on the Markov regenerative processes coupled with fluid model, we discover that the adaptive admission control (AAC) mechanism at the WiFi access point (AP) improves the response time and fairness of IoT traffic over the lossy WiFi links. To this end, under the proposed AAC, packets are admitted into the AP in such a way that the fractions of packets in the AP buffer belonging to the different IoT devices are balanced resulting in a comparable level of service. We furthermore prove the stability of the system dynamics under AAC which provides important practical insights in designing home WiFi IoT system.

This chapter considers the challenges faced by network operators and service providers accommodating the increasing traffic demands in cellular networks in the most efficient yet inexpensive way. It proposes that these challenges are addressed by offloading part of the traffic to femto cell access points (FAPs) and WiFi access points (WiFiAPs). Whereas 4G micro and pico cell base stations are assumed to be managed by the network operator in terms of setup and maintenance, FAPs and WiFiAPs are normally bought and operated by the end-user. The main difference between these two solutions is that the FAPs operate on the frequency bands assigned to the network operator by national regulators, while WiFiAPs work on unlicensed spectrum. This chapter analyzes the pros and cons of such approaches, and the tradeoffs related to the different mechanisms employed in cellular and WiFi networks for interference management. Moreover, various methods for traffic offloading by the mobile network operator are discussed in detail, including local IP access (LIPA), selective IP traffic offloading (SIPTO), IP flow mobility (IFOM), access network discovery and selection function (ANDSF), and Hotspot 2.0, etc. In the experimental part of this chapter, means for traffic management from the network operator's perspective are discussed, taking into account costs and energy savings. Furthermore, a novel resource usage coordination concept in conjunction with the WiFi offloading concept is presented. Introduction The traffic served by cellular networks grows significantly on a yearly basis, making the efficient, fair, and inexpensive management of users’ traffic demands a real challenge. Various forecasts provided both by legal bodies and commercial companies show that this trend will not change in the future. One can, for example, consider the expectations provided in Table 6.1, created based on the data delivered in the Cisco Visual Networking Index [1, 2] in 2012 and 2013. It is shown that the monthly average traffic generated by mobile devices is foreseen to grow exponentially. Based on [3], it can be stated that in 2017 IP traffic originating from mobile devices will comprise more than 13% of fixed IP traffic, while in 2013 this comprised only around 4% of fixed IP traffic.

This paper studies how to maximize the per-user-based throughput in an M-tier heterogeneous wireless network (HetNet) by optimally managing traffic flows among the access points (APs) in the HetNet. The APs in the first M - 1 tiers can use the licensed spectrum at the same time whereas they share the unlicensed spectrum with the APs in the Mth tier by the proposed opportunistic CSMA/CA protocol. The APs that access the licensed and unlicensed spectra simultaneously are able to integrate their spectrum resources by the carrier aggregation technique. For an AP in each tier, the tight bounds on its mean spectrum efficiencies in the licensed and unlicensed spectra are derived in a low-complexity form for general random channel gain and AP association weight models, and they can provide some insights into how channel gains, AP association weights and void AP probabilities affect the mean spectrum efficiencies of APs. The per-user throughput based on the mean spectrum efficiencies in the licensed and unlicensed spectra is found and maximized by the proposed decentralized traffic management scheme. Numerical results show that the mean spectrum efficiencies and the per-user throughput can be significantly improved by the proposed decentralized traffic management scheme.

Wireless fidelity (WiFi) networks are deployed in several varied environments all around the World. Usually, the wireless fidelity access points are always on in houses and other small companies. In buildings of large companies and public organizations and in university campuses the number of access points is elevated; they are powered using power over the ethernet and are always on. Consequently, they consume a considerable amount of electric energy. The last versions of the International Electric and Electronic Engineers 802.11 standardized procedures to save energy in a wireless fidelity terminal but not in the access point. We designed a formal method to show when energy can be saved in wireless fidelity access points considering different power supplies for the access point: an electric energy battery and a standard voltage supply. We use an external battery that stores electric energy during an interval of time from a standard voltage supply (Charge period). After that interval (Discharge period), the energy supply for the access point is the external battery. Those intervals of time are repeated sequentially (Charge and Discharge cycles). We verified our formal model implementing a hardware circuit that controls the power supply for the access point. The amount of energy saving for a large number of of access points during a long period of time is considerably high.

we apply the concept of the common spectrum coordination channel (CSCC) etiquette protocol to form a spectrum sharing protocol among access points in 802.11 networks. It efficiently allocates operating frequencies among access points. As a result, it reduces interference from wireless devices using the 802.11 MAC/PHY protocol. This is motivated by the lack of intelligent spectrum sharing among Wi-Fi access points. We show that the CSCC protocol is not suitable for point to multipoint (PMP) networks. Through simulation, our proposed spectrum sharing protocol improves throughput and reduces media access delay in Wi-Fi networks.

Wireless Wi-Fi networks are becoming increasingly popular these days. Wi-Fi zones appear in more and more public places. However, despite all the advantages of Wi-Fi networks, such networks are often subject to attacks: an attacker can gain access to the local network of a user or an organization and use the traffic for criminal purposes.This article analyzes the security issues of Wi-Fi access points. The work investigates the frames of Wi-Fi 802.11 standard, which defines various types of frames, used for communication, management and control of a wireless connection, to detect attacks. In order to track attacks on the access point, the following access point parameters can be obtained from the frames are checked: MAC address, SSID, RSSI.Various types of frames of the Wi-Fi 802.11 standard are also being explored to track attacks on networks, such as detecting and capturing Disassociation and Deauthentication frames, which may indicate an attack.

In today's modern life, wireless access to the internet is in many cases a necessity. The purpose of the overall project was to design and build a smart mobile repeater. And how to create a portable Access Point with Wi-Fi repeater capabilities. The repeater will navigate an environment in search of the signal strength from a distant router. After it sufficiently acquires a high-level signal, it will act as a relay so that other computers may connect to the router through it. A Raspberry Pi WIFI Extender is a cheap and power efficient way of increasing the total range of your WIFI Network. A WIFI extender differs a fair bit from a WIFI access point. The main difference being that instead of getting its network connection from Ethernet, it instead gets its network connection from a WIFI adapter. For this reason, to complete this tutorial you will require two WIFI adapters, one of these must be access point capable. You will face a fair bit of degradation in the speed of your network connection when connecting to the WIFI repeater. The main reason for this is that you must wait for the traffic to go over your initial Wi-Fi connection then be repeated from your Raspberry Pi for devices to connect to.