A survey on hybrid beamforming techniques in 5G : architecture and system model perspectives

The increasing wireless data traffic demands have driven the need to explore suitable spectrum regions for meeting the projected requirements. In the light of this, millimeter wave (mmWave) communication has received considerable attention from the research community. Typically, in fifth generation (5G) wireless networks, mmWave massive multiple-input multiple-output (MIMO) communications is realized by the hybrid transceivers which combine high dimensional analog phase shifters and power amplifiers with lower-dimensional digital signal processing units. This hybrid beamforming design reduces the cost and power consumption which is aligned with an energy-efficient design vision of 5G. In this paper, we track the progress in hybrid beamforming for massive MIMO communications in the context of system models of the hybrid transceivers' structures, the digital and analog beamforming matrices with the possible antenna configuration scenarios and the hybrid beamforming in heterogeneous wireless networks. We extend the scope of the discussion by including resource management issues in hybrid beamforming. We explore the suitability of hybrid beamforming methods, both, existing and proposed till first quarter of 2017, and identify the exciting future challenges in this domain

Journal of Telecommunications and Information Technology, nr 3

kwartalni

Low-Power Wide-Area Networks: A Broad Overview of its Different Aspects

Low-power wide-area networks (LPWANs) are gaining popularity in the research community due to their low power consumption, low cost, and wide geographical coverage. LPWAN technologies complement and outperform short-range and traditional cellular wireless technologies in a variety of applications, including smart city development, machine-to-machine (M2M) communications, healthcare, intelligent transportation, industrial applications, climate-smart agriculture, and asset tracking. This review paper discusses the design objectives and the methodologies used by LPWAN to provide extensive coverage for low-power devices. We also explore how the presented LPWAN architecture employs various topologies such as star and mesh. We examine many current and emerging LPWAN technologies, as well as their system architectures and standards, and evaluate their ability to meet each design objective. In addition, the possible coexistence of LPWAN with other technologies, combining the best attributes to provide an optimum solution is also explored and reported in the current overview. Following that, a comparison of various LPWAN technologies is performed and their market opportunities are also investigated. Furthermore, an analysis of various LPWAN use cases is performed, highlighting their benefits and drawbacks. This aids in the selection of the best LPWAN technology for various applications. Before concluding the work, the open research issues, and challenges in designing LPWAN are presented.publishedVersio

Applications of Repeated Games in Wireless Networks: A Survey

A repeated game is an effective tool to model interactions and conflicts for players aiming to achieve their objectives in a long-term basis. Contrary to static noncooperative games that model an interaction among players in only one period, in repeated games, interactions of players repeat for multiple periods; and thus the players become aware of other players' past behaviors and their future benefits, and will adapt their behavior accordingly. In wireless networks, conflicts among wireless nodes can lead to selfish behaviors, resulting in poor network performances and detrimental individual payoffs. In this paper, we survey the applications of repeated games in different wireless networks. The main goal is to demonstrate the use of repeated games to encourage wireless nodes to cooperate, thereby improving network performances and avoiding network disruption due to selfish behaviors. Furthermore, various problems in wireless networks and variations of repeated game models together with the corresponding solutions are discussed in this survey. Finally, we outline some open issues and future research directions.Comment: 32 pages, 15 figures, 5 tables, 168 reference

Internet of Things From Hype to Reality

The Internet of Things (IoT) has gained significant mindshare, let alone attention, in academia and the industry especially over the past few years. The reasons behind this interest are the potential capabilities that IoT promises to offer. On the personal level, it paints a picture of a future world where all the things in our ambient environment are connected to the Internet and seamlessly communicate with each other to operate intelligently. The ultimate goal is to enable objects around us to efficiently sense our surroundings, inexpensively communicate, and ultimately create a better environment for us: one where everyday objects act based on what we need and like without explicit instructions

Smart vest for respiratory rate monitoring of COPD patients based on non-contact capacitive sensing

In this paper, a first approach to the design of a portable device for non-contact monitoring of respiratory rate by capacitive sensing is presented. The sensing system is integrated into a smart vest for an untethered, low-cost and comfortable breathing monitoring of Chronic Obstructive Pulmonary Disease (COPD) patients during the rest period between respiratory rehabilitation exercises at home. To provide an extensible solution to the remote monitoring using this sensor and other devices, the design and preliminary development of an e-Health platform based on the Internet of Medical Things (IoMT) paradigm is also presented. In order to validate the proposed solution, two quasi-experimental studies have been developed, comparing the estimations with respect to the golden standard. In a first study with healthy subjects, the mean value of the respiratory rate error, the standard deviation of the error and the correlation coefficient were 0.01 breaths per minute (bpm), 0.97 bpm and 0.995 (p < 0.00001), respectively. In a second study with COPD patients, the values were -0.14 bpm, 0.28 bpm and 0.9988 (p < 0.0000001), respectively. The results for the rest period show the technical and functional feasibility of the prototype and serve as a preliminary validation of the device for respiratory rate monitoring of patients with COPD.Ministerio de Ciencia e Innovación PI15/00306Ministerio de Ciencia e Innovación DTS15/00195Junta de Andalucía PI-0010-2013Junta de Andalucía PI-0041-2014Junta de Andalucía PIN-0394-201

Efficient IPv6 Neighbor Discovery in Wireless Environment

As the address space of IPv4 is being depleted with the development of IoT (Internet Of Things), there is an increasing need for permanent transition to the IPv6 protocol as soon as possible. Nowadays, many 3GPP (3rd Generation Partnership Project) Networks have implemented or will implement IPv6 in the near future for Internet access. These networks will also use NDP (Neighbor Discovery Protocol), which is the IPv6 tailored version of ARP (Address Resolution Protocol). The protocol is responsible for address auto-configuration, maintaining lists of all neighbors connected to a network, verifying if they are still reachable, managing prefixes and duplicate address detection. The protocol is defined in RFC 4861 and although it works fine for wired connected devices, it has been proven highly inefficient in terms of battery lifetime saving, when wireless networks came to the market and its use increased tremendously. This thesis work is a continuation of a previous master thesis and complements the work done previously by showing how the solutions suggested in the new draft can be implemented at the router and host side and practically confirms the previous results of the theoretical analysis through simulation scenarios of sleep and wake-up of the nodes, performed in OMNeT++. Subsequently, the scalability of the system as a whole was analyzed with a simulation model containing a range of hosts from 1 to 100, and shows it can operate efficiently on a larger scale, reducing multicast messaging by almost 100%, presumably saving their battery power.The introduction and rise of Internet of Things (IoT), and the use of more and more wireless devices in the communication between users, has depleted the available addresses of IPv4. The introduction of the new IPv6 protocol solves the address depletion problem, but on the other hand, many of the existing protocols have to be redesigned. This thesis is based on RFC 4861’s NDP (Neighbor Discovery Protocol for IPv6 Networks, the equivalent protocol of ARP (Address Resolution Protocol) for IPv4 Networks. Like ARP, NDP is used in all Networks, wired or wireless, and it’s main feature is to check and update periodically the state of the Network, provide L2 addresses to hosts in the same Network and verify their reachability. While wired devices experience no issues regarding power supply, as they are constantly hooked to a power source and rarely experience network failures, wireless devices have limited power, as they rely on battery lifetime. This is also the case of machines running NDP - the protocol relies on periodic exchange of multicast ICMPv6 (Internet Control Message Protocol version 6) control messages, creating unnecessary traffic overhead in the Network, as all hosts in a Network would receive those messages, regardless if they are meant for them or not. As a general working mode of a battery operated device, one enters predefined sleeping cycles (stand-by), which are designed by each manufacturer in different ways. Therefore, multicast signaling inside Networks disrupt those sleeping cycles, causing increased battery consumption, as a result of more required processing power and more consumed bandwidth. RFC 6775, together with [3], propose updates to NDP, which would solve the problems mentioned above. The major update is that each host can update the router about its state, by sending unicast messages, without involving the other hosts in the Network. The router, instead of sending periodic control messages to every host, it sends control messages to each host separately in specific time intervals. Only when a major change occurs in the Network, for instance an addition of a new host, or when a host leaves the Network, multicast messages are sent to every host to update their state. Together with the establishment of unicast signaling, a new method of address registration is introduced in the documents cited above, called Address Registration Option. This registration method is fully compatible with the two standard mechanism which provide the L3 addresses to hosts - Stateless Address Autoconfiguration (SLAAC) and Dynamic Host Configuration Protocol (DHCP). The previous thesis work took the first steps in implementing the proposed protocol changes, by investigating functions inside RADVD - the Router Advertisement Daemon, run on all routers and responsible for sending the multicast periodic control messages to the hosts (Router Advertisements). A full implementation of the proposed changes require covering both sides of the Network, i.e Host and Router. While RADVD is handling the Router side, the implementation at the Host side needs to be done inside the Linux Kernel. In this thesis work, the RADVD implementation was completed and possible implementation methods were shown inside the Linux Kernel. Due to the overall complexity of the Linux Kernel, while the proposed code could cover most aspects from RFC 6775, it wasn’t possible to test it, in order to conclude how much workload is left. Simulations took place to compare the two protocols and verify, in what extend these proposed changes can potentially improve battery lifetime. So, sleep and wake up scenario was tested in same time intervals in order to observe Network traffic. The goal was to have a decrease in control messages in the case where the suggested changes were applied. Different number of hosts were selected to see if these changes can be applied to larger network. In both cases, the best case scenario was tested and parameters which would normally hinder network performance were neglected. This decision was made to reduce the complexity of the Network as well. The results of the simulations indicated that there could be a decrease in control messages and the Network seems stable and scalable as number of host increases