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Handover Problems and Solutions for 5G Communication Technology

Introduction The continuously increasing demand of wireless communications impels the fast development of the next generation wireless communication technology. The 5G communication technology, which scheduled to be realized in the year beyond 2020, is still on its researching stage. Aim at the novel handover problems in ultra-dense network deployments and high-band communications in 5G scenarios. Handover is an important content of radio resource management. The processing and optimization of handover has a great effect on improving the effectiveness and reliability of the whole system, which plays an important role in modern wireless communication. In 5G mobile communication system, it is necessary to provide high bandwidth and high transmission rate service for different kinds of terminals in several scenarios. Handover technology is an important guarantee of communication continuity and service quality, and it is very important to the overall performance of the network. We aim to understand the possible solutions to solve the handoff challenge in hybrid 5G. As we move toward 5G, environment becomes so complex that the handoff problem faces with new challenges. 5G will not completely replace the existing technologies but be more integrative and hybrid, combining with existing technologies to provide high-rate and seamless communication service. The data rate in 5G is expected to be roughly 1,000x compared with current technology, hence the handoff problem requires a faster processing. Furthermore, as the number of Base Stations and mobile devices increases, the centralized control may not be efficient. On the contrary, more intelligent mobile devices can play important roles in handoff. Moreover, increasingly serious data security problem reminds users do not share their private information with others. We aim to understand a user centered handoff scheme for hybrid 5G environments and we aim to analyze the proposed solutions and its challenges Handover in Mobile Communication Systems A handover or handoff is a process in mobile communications and telecommunication systems in which a connected cellular call or a data session is transferred from one base station (cell site) to another without the session getting disconnected. Cellular services are based on mobility management and handover, allowing the user to be moved from one cell site range to another or to be switched to the nearest cell site for better performance. Handoff can also be described as a process in which a link is transferred from one base station to another base station due to lack of signal strength. Several operations are included in the handoff process such as initiating the handoff, allocating the channel, breaking the connection with the old base station, choosing the new base station. Types of Handoff Handoffs can be classified in two categories – hard and soft handoffs. A hard handoff can be thought of as a break before make connection. The base station transfers the user’s call to another cell and the drops the call. In the case of hard handoff, the users link to the prior base station is terminated before or as the user is transferred to the base station of the new cell. In anycase the user cannot be linked to more than one base station at any given time. Hard handoff is used in frequency division multiple access and time division multiple access where adjacent channels use different frequency ranges in order to minimize channel interference. In the case of soft handoff, a connection to the new base station is made before the connection to the previous base station is disconnected. It is performed through the parallel use of source and destination channels over a period of time. Soft handovers allow parallel connection between three or more channels to provide better service. Soft handoff is effective in poor coverage areas. Different phases in Handover Handoff Initiation Phase: This phase decides the requirement of handoff. It triggers handoff on the basis of information collected about network, mobile node and user preferences from different layers’ likes’ network layer, transport layer and application layer. These layers provide the information such as signal strength, bandwidth, link speed, throughput, jitter, cost, power, user preferences and network subscription etc. Based on this information, handoff is initiated at appropriate time. Handoff Decision Phase: After initiating handoff in first phase, the decision making phase decides the optimal networks for handoff. The comparison is made between the current and neighboring networks based on parameters such as QoS, signal strength, velocity, direction, cost, etc. There are many methods proposed to take decision about networks such as MADM approaches, fuzzy logic, genetic algorithms, for deciding the destination network. The decision making phase chooses the optimal network for transfer but the actual link transfer takes place in the next phase Handoff Execution Phase: After the selection is made and decision about the target network is taken, link transfer takes place in this phase in which the existing link is re-routed to the new network in a seamless manner. This phase also includes the reauthentication, re-association and re-authorization, and the transfer of user’s context information. Three strategies are used to detect the need of handoffs Mobile-controlled-handoff (MCHO): The mobile node keeps on monitoring the signals of the current and neighboring base stations and triggers handoff as and when needed. Network-controlled-handoff (NCHO): The base stations monitor the signal between user and the network. It initiates handoff process when there is a drop in the signal strength as the user moves away from the base station. Mobile-assisted-handoff (MAHO): The mobile node assists the network to measure the signal strength between the user and the base station. The networks make the handoff decision based on reports from the mobile node. Delays in Handoffs The complete handoff process is carried out by co-ordination and co-operating entities of different layers of OSI model. However, this leads to a system with delay. When data has to be passed between different layers’ different kinds of delays are introduced which hinder in quality of service in handoffs. Link layer delay: This layer is responsible for horizontal handoffs. Before the mobile node switches to neighboring base station, scanning is done. During scanning, mobile node scans all the nearby base stations. It takes some time and sometimes mobile disconnects and then connects to new base station. This kind of delay which is introduced during scanning and call setup with new base station is link layer delay Network layer delay: This layer is responsible for vertical handoff which involves obtaining the IP address of new network and then switching the call from one base station to another which may cause more delay. Thus this kind of delay is called network delay. Transport Layer delay: Many protocols sit at this layer to monitor and manage transport layer handoff. Most important protocol in this case is SCTP which is responsible for multistreaming during handoff. SCTP makes new connection with the neighbor network/base station while maintaining connection with the old. As new connection becomes stable, it breaks the connection with the old base station. This disconnection can be delayed due to reauthentication or re-association phase. Application layer delay: This delay occurs when certain properties of application layer get modified e.g. change in IP using Session initiation protocol. User Centered Handoff Scheme for 5G Environments 5G will not replace all the current technologies completely but will try to combine with existing technologies to provide higher data rates and seamless communication services. As 5G technologies come into picture, the environment starts becoming more complex and the handoff problem faces new challenges. Data rates in 5G are expected to be higher than the current 4G technology, and as the number of base stations and mobile devices increase dramatically, the use of centralized control may not be efficient. On the contrary, more intelligent mobile devices can play important roles in handoff. Furthermore, increasing data security issues leads to users not sharing their private information with others. Therefore, we want a fast, distributed, privacy preservation and a user centered handoff scheme in hybrid 5G environments. Consider a scenario in the figure below in which a hybrid 5G environment is constructed using 3G, LTE, WIMAX and 5G base stations. In this scenario, users may need to transfer their network connections from one base station to another base station. This is the handoff problem wherein a user has several available base stations and the user needs to decide to the base station to which the network connection should be transferred. In the figure below as the user moves far away from the 3G base station, the signal strength received from that base station reduces drastically that the user has his network connection to a new base station. The user has 3 choices to which he can transfer his connection to, they are the LTE, WIMAX and 5G base stations. The user has to decide which base station is to be selected. In this case the handoff problem appears straightforward task of the user selecting the best performing base station. However, it is difficult for the user to know the network selection choices being made by other users in the network. If the same base station is selected by many users, there are high chances of the user being blocked by the network. Therefore, the objectives of network selection are to select a high performance base station and avoid being blocked. The handoff problem in general can be solved by the network centered approach and the user centered approach. In the network centered approach, networks are responsible for computing and making the decisions while in the user centered approach, users will be in charge of the network selection. To satisfy the requirement of privacy-preservation in hybrid 5G environment, users are not suggested to send their private information out. User Centered Handoff Scheme for Hybrid 5G Environments Figure 1 With this limitation networks can’t obtain adequate information from the users for the network selection. Thus the user centered approach is more suitable for the hybrid 5G environments than the network centered approach. Users are divided into two classes: non handoff users and handoff users. Non-handoff users will stay in the connections with their current base stations while handoff users will transfer their network connections to new base stations based on limited local information. Local information is the private information of the user which has parameters of the base stations and two parameters related to public information (i.e., the total numbers of handoff and non-handoff users inside each available base station). When a user has to select a new base station in a handoff, the user will calculate the achievable data receiving rates of all the available base stations. Additionally, the user has to infer the network selection behaviors of all the other users to estimate its block probability for each available base station. By jointly considering the achievable data receiving rate and the block probability, the user can select the most appropriate base station in a handoff. Relation between Users Based on limited local information, each handoff user tries to select a new base station which can provide the maximum achievable data receiving rate and minimal block probability. The block probability of a handoff user relates to the network selection behavior of other handoff users and a user has no idea of other handoff users due to privacy preservation. Block probability calculation relies on inference made by a handoff user to another handoff user. To assist a handoff user in inferring the network selection behaviors of other handoff users, it is important to understand the relation between any two handoff users based on their set of available base stations. The relation between a pair of handoff users can be divided into independent relation and correlated relation. When the two users are independent, the network selection behavior of user 1 has no direct impact on user 2 and vice versa. Therefore, in the handoff process a user needs to consider only those users with whom he has some amount of correlation. Correlated relation refers to the scenario when there is atleast one base station available to both the users. To understand the extent to which the two users are correlated, a metric named correlation degree is defined. The correlation degree of two users is the probability of selecting a base station that is available to both from a set of base stations that are available to each user. Figure 2 Figure above describes the calculation of correlation degree L(ui,uj) where ui and uj are two users and Bi(t) and Bj(t) are the set of base stations available to each user. x is the set of base stations that are available to both. The value of x is zero if both the users are independent and the correlation degree is zero in this case. If the coreelation degree is 1, all the base stations are available to both the two users. Network Initiated Handover In Network Initiated Handover the user gets handover information from Base Station 1. The user then performs quality measurements on Beam Reference Signals (BRSs) from neighboring cells. The user then sends the quality measurement report back to Base station 1. As soon as the Base Station 1 receives the information from the user, it replies with handover command containing connection re-configuration along with target cell Base Station 2. Using the command user then completes handover with target cell base station 2. User Initiated Handover Initially the user receives measurement configuration from serving cell base station, it performs quality measurements on BRSs from neighboring cells. The user sends measurement report to serving cell base stations and the base station responds with list of possible neighboring cells to complete the handover. The Base station then provides measurement configuration for user to complete the handover with target base station 2. The user then completes handover with target cell base station 2. Figure 3 Ultra Dense Networks Ultra-Dense Networks (UDN) are networks where there the number of cells is greater than active users. In other words, the density of access points is greater than the density of users. Different quantitative definitions exist for Ultra dense networks exist such as when the measure of cell density is greater than 1000 cells / Km squared or when there are 600 active users / Km squared. Small cells in Ultra Dense Networks are classified into fully functioning base stations which include picocells and femto-cells. It also includes macro extension access points which includes relays and Remote Radio Heads (RRHs) Ultra Dense Network with Small cells Figure 4 Small Cells in 5G Technology Small cells are short range, low power base stations which cover a small geographical area or indoor/outdoor applications. Small cells do have all the basic characteristics of a conventional base station and it is also efficient in handling high data rate for individual users. In advanced LTE and 5G deployments, small cells will play a crucial role in the efficient delivery of high speed mobile broadband and other low latency applications. Small cells are further divided into three classes, they are femtocells, picocells and microcells. Small cells are classified into these three classes based on the number of users the network can handle and the coverage area. Femtocells – These are small mobile base stations which provide extended coverage for residential applications. They have a coverage area of about 10 to 50 meters. Femtocells are low cost, can support upto 16 users and primarily used for indoor applications. Picocells – They are another category of small cells which provide extended coverage and are primarily used for small enterprise applications. They have a coverage area of 100 to 250 meters and can support upto 64 users. Picocells are low cost and require around 250 milliwatts of power. Microcells – In comparison to femtocells and picocells, microcells support a slightly larger number of users. They are capable of covering larger cell size and are used for applications such as smart cities, smart metro due to their high transmission power. As conventional mobile networks have limitations for further enhancements due to technology, infrastructure and bandwidth, small cells are used with advanced technologies like massive MIMO and beamforming to increase spectrum efficiency and data rate. Small cells work similar to conventional cells with the use of advanced techniques like MIMO, beamforming and millimeter waves for transmission. Small cell enables the deployment of low power transmitting stations. Small cell hardware units reduce complexity making the implementation faster and easier. Small base stations (transceivers) can be fixed on a wall for indoor applications and small towers. Backhaul connections can be made using fiber connections, wired connection and via microwave links. Configuration is less complex and it just needs to be connected to the power source and backhaul. Small cells are primarily added to increase capacity in hot spots with high user demand and to fill in areas not covered by the macro network – both outdoors and indoors. They also improve network performance and service quality by offloading from the large macro-cells. Frequency, power and antenna techniques are some of the factors that affect the cell coverage and data capacity. Small cells can be used extensively in future applications which are given as follows: Disaster management applications and drones Support mission critical services that require low latency and highly reliable network. Internet of thing applications like smart city, smart home and smart healthcare. Support huge number of users during special events like sports and games with multiple cell deployments. Since 5G technology is a future framework to support various applications, it has to meet all necessary specifications. Small cell concept is an apt solution for delivering enhanced mobile broadband, low latency and reliable service to users. Higher order modulation techniques, MIMO technology and millimeter wave spectrum will ensure proper working of future small cell deployments. Handover Management in small cells Several factors need to be accounted while designing handover mechanisms between small cells. The varying link quality of small cells implies that handover between small cells should involve low amount of signaling. Due to the small cell sizes frequent handovers may occur which could contribute in a major way to the signaling load on the network. Load on the core network can be minimized if handovers are anchored locally whenever possible. Additionally, the access control features at small cells mean that the admission control decisions at the target small cell during handover should account for the access privileges available for the mobile user and must not impact the performance of the users already being served at the target small cell. Sectoring Sectoring is the process of dividing a congested cell into smaller cells each having its own base station and their antenna height being reduced. Cell sectoring leads to an increase in the channel capacity. Omni directional antennas at the base stations are replaced by several directional antennas. Cell sectoring is done to reduce co-channel interference. Figure 4. Cell Splitting with Umbrella Approach The cell shape is chosen to be hexagonal. This is due to the fact that it successfully avoids overlap that would have occurred between circular shaped cells. The Umbrella approach saves one from building multiple base stations. In the Umbrella cell approach, a single base tower serves all the split cells via antennas which are mounted on it at different heights. Cell splitting leads to increased number of antennas per base station and an increase in the number of handoffs. Figure 5. Skipping With the use of small cells, the number of handoffs required increases in comparison to conventional networks. To overcome this problem, a skipping scheme can be used to reduce the unnecessary handovers. Figure 6. from Reference [3] Types of Skipping techniques: Alternating Handover(a) – This is the simplest of all the skipping schemes. If a user trajectory is passing through lot of small cells it skips every alternate cell. This nearly reduces the number of handovers required to half. Location-Aware Handover Skipping(b) – The location aware handover skipping scheme looks for the shortest distance between the user trajectory and the target base station to decide the handover skipping. The handover skips associating to the target base station if and only if the minimum distance along the user trajectory and the target base station becomes larger than a pre-defined threshold L. This threshold L can be designed such that the user can skip the base stations in which the trajectory passes through the cell edge only. Cell-Size Aware Handover Skipping(c) – Cell-size aware handover skipping scheme enables the users to skip handover to target base stations that have a footprint less than a pre-defined threshold S. Since the cell dwell time is dependent on the footprint size of the base station, size aware skipping scheme aims at avoiding large blackout durations. Hence, it allows users to skip small sized cells and associate with large sized cells. Hybrid Handover Skipping: The true cell dwell time is not correctly reflected by the location aware skipping nor the size aware skipping. Hence, combining both schemes gives a better inference about the cell dwell time, which can improve the handover skipping decisions and performance. Subsequently, the hybrid HO skipping scheme combines both location awareness and cell-size awareness to decide which base stations are to be skipped. That is, it takes user location and cell area into account while making the decision for the handoff. Conclusions We reviewed a user centered approach for handover in hybrid 5G environment and understood that a user centered approach is needed for 5G technology. We also reviewed 5G cell structure and its impact on handover process. References Li Qiang, Jie Li, Corinne Touati “A User Centered Multi-Objective Handoff Scheme for Hybrid 5G Environments”, IEEE Commun. Mag., vol. 5, no., 3 July-Sept. 1 2017. R. Arshad, H. Elsawy, S. Sorour, T. Y. Al-Naffouri and M. Alouini, “Handover Management in 5G and Beyond: A Topology Aware Skipping Approach,” in IEEE Access, vol. 4, pp. 9073-9081, 2016. doi: 10.1109/ACCESS.2016.2642538 Nisha Panwar, Shantanu Sharma, Awadhesh Kumar Singh “A survey on 5G: The next generation of mobile communication” Physical Communication, Volume 18, Part 2, March 2016
Statistics homework help. This is a paper that is focusing on the context of nursing practice and healthcare delivery review. The paper also provides additional information to use in writing the assignment paper well.,Context of nursing practice and healthcare delivery review,Assignment: Literature Review: The Use of Clinical Systems to Improve Outcomes and Efficiencies,New technology—and the application of existing technology—only appears in ,healthcare settings, after careful and significant research. The stakes are high, and new clinical systems need to offer evidence of positive impact on outcomes or efficiencies.,Nurse informaticists and healthcare leaders formulate clinical system strategies. As these strategies are often based on technology trends, informaticists and others have then benefited from consulting existing research to inform their thinking.,In this Assignment, you will review existing research focused on the application of clinical systems. After reviewing, you will summarize your findings.,To Prepare:,Firstly, review the Resources and reflect on the impact of clinical systems on outcomes and efficiencies within the context of nursing practice and healthcare delivery., Secondly, conduct a search for recent (within the last 5 years) research focused on the application of clinical systems. The research should provide evidence to support the use of one type of clinical system to improve outcomes and/or efficiencies, such as “the use of personal health records or portals to support patients newly diagnosed with diabetes.”, Thirdly, identify and select 4 peer-reviewed research articles from your research.,The Assignment: (5 pages),In a 4- to 5-page paper, synthesize the peer-reviewed research you reviewed. Format your Assignment as an Annotated Bibliography. Be sure to address the following:,Firstly, identify the 4 peer-reviewed research articles you reviewed, citing each in APA format., Secondly, summarize each study, explaining the improvement to outcomes, efficiencies, and lessons learned from the application of the clinical system each peer-reviewed article described. Be specific and provide examples., In your conclusion, synthesize the findings from the 4 peer-reviewed research articles,Attachments,Click Here To Download,Statistics homework help
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The type of diabetes mellitus most strongly associated with obesity is Type 2 or non-insulin-dependent diabetes.

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According to researchers cited in the text, what is the minimum number of miles a person should walk each week to gain optimal health benefits?Question 3 options:10 to 15 miles5 to 10 miles15 to 20 miles20 to 25 miles
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Health Sciences homework help

Health Sciences homework help. This is a paper that is focusing on the counterrorism or cyberspace operation research and analysis. The paper also provides additional information to use in writing the assignment paper.,Counterrorism or cyberspace operation research and analysis,Objective: This assignment, in accordance with undergraduate academic endeavors, provides an opportunity to evaluate assimilation of course topics, and sharpen and evaluate students’ research & critical thinking skills.,Type: This assignment consists of a research-analysis paper approximately four pages in length, double-spaced (This page count does not include a title page, abstract (optional), table of contents (optional). Reference listing page(s), or end-notes page(s) (if used)). The source material should result primarily from self-led research of the required texts and readings from this course. The paper should have approximately four pages of content which are the written results of your research efforts.,Topic: Research and analyze a counterrorism or cyberspace operation which primarily utilized defensive counterintelligence support. Discuss the historical events that let to the mission, identify the agency and the opponent, and identify the defensive principles of deter and detect in the countermeasures. Some examples of relevant counterterrorism operations may include: 1983’s Marine Barracks in Lebanon, 1993 WTC bombing, 1996 USS Cole, 1998 US Embassies in Africa, Sept 11 2001, 2005 London bombings, etc. Some examples of relevant cyberspace operations may include: 2001-2005 ,Chinese cyberespionage,. (Titan Rain), 2011 Duqu worm(surveillance malware targeted at Iranian nuclear facilites), 2012 Flame (surveillance malware targeted at the Iranian oil industry), 2012-2013 cyberattacks against U.S. banking industry, etc.,Format: Your paper requires a Title page, citations, and a References list. Your paper should be in the Chicago style.,Remember, ensure  that the paper is at least three pages exclusive of the cover and the reference pages. Also, ensure that you include all the references you use in finding research for this assignment paper. References should be at least three for the paper. All references, citation, and writing should follow the Chicago formatting and styling guidelines. Finally, ensure you focus on the assignment topic in detail.,Attachments,Click Here To Download,Health Sciences homework help

Long Island University Brooklyn SARS-CoV-2 Infection in Children Article Review

term paper help Long Island University Brooklyn SARS-CoV-2 Infection in Children Article Review.

In this assignment, you are required to address questions based on a published research article. You will select this article on your own from a reputable journal in your field or area of interest and readings in the course thus far. The article must have been peer reviewed before being published. Please contact the library for help if you need assistance finding peer reviewed articles. You also are required to post the summary of your responses to share it with your peers. You will need to:

Attach the accompanying article or provide a link to it.
Provide feedback to one of your peers.
Learn from your peers’ feedback.
Explain what you gained giving and receiving feedback.

Action Items

Initial Post: Create a post in the discussion board. Your research article summary should contain all your responses to the questions asked.

Based on your selected published article from a reputable journal in your field or area of interest (for example, articles in the Academy of Management Journal, American Educational Research Journal, and other such journals), review the article focusing on issues related to content covered thus far in the course. Write a summary essay of your review. In particular, address the following:

What is the research problem or research question addressed by the study?
What type of research design was used, e.g. experimental, observational?
What are the variables, and which ones are dependent and independent, or continuous or discrete?
Describe the population of the study or sampling frame, the sampling technique, and sample size.
Describe the data collection methods, including procedures, instruments, and unit of analysis.
What descriptive statistics were used in the study to summarize the data (graphs, summary tables, etc.)?
Describe the statistical techniques used to analyze the data. Are these techniques adequate? Why or why not?
What do the results of the study mean?
Note: Be sure to attach or provide a link to your selected article when posting the summary of your responses to the discussion board.

Long Island University Brooklyn SARS-CoV-2 Infection in Children Article Review

UV Data Beneficial Mining in Small Business Ensure Security Processes Discussion

UV Data Beneficial Mining in Small Business Ensure Security Processes Discussion.

. Your goal is to develop a strong research question together based on this topic, changing whatever you need to so that the research question is debatable, researchable, feasible, and makes a contribution to ongoing conversations about the topic. It’s also fine if your group develops multiple strong research questions, but the focus should be on the quality of the question rather than number of questions. This may involve finding related sources to analyze and share with each other, doing background research, asking questions, etc. (see readings for specific ideas about how to move this work forward). Sample
UV Data Beneficial Mining in Small Business Ensure Security Processes Discussion

Sources of Capital Essay

The entrepreneur’s likely sources of venture capital are banks, private capital investments, and customer contributions. With sufficient capital investments, the entrepreneur can easily secure loans to aggressively pursue his business goals and objectives. Featured as a risk taker, innovative, and visionary coupled with initiative and true business abilities, these qualities make him worth of external capital injection. Success is evident from gains made in business sales revenues in the range of $750,000 a year. This is also demonstrated by a striking rise from a humble beginning when the business consisted of an old computer and a single two head machine to its current status. Advantages and Disadvantages of Sources of Capital A bank loan is a reliable source of capital for any business enterprise. Bank loans are offered at competitive interest rates which are pegged on current market rates (Grossman

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