Wireless Broadband Services Research Articles

Optimizing radio resources for multicasting on high-altitude platforms

High-altitude platforms (HAPs) are quasi-stationary aerial wireless communications platforms meant to be located in the stratosphere, to provide wireless communications and broadband services. They have the ability to fly on demand to temporarily or permanently serve regions with unavailable infrastructure. In this paper, we consider the development of an efficient method for resource allocation and controlling user admissions to multicast groups in a HAP system. Power, frequency, space and time domains are considered in the problem. The combination of these many aspects of the problem in multicasting over an OFDMA HAP system were not, to the best of our knowledge, addressed before. Due to the strong dependence of the total number of users that could join different multicast groups on the possible ways we may allocate resources to the different multicast groups, it is important to consider a joint user to multicast group assignments and radio resource management across the groups. From the service provider’s point of view, it would be in its best interest to be able to admit as many users as possible, while satisfying their quality of service requirements.The problem turns out to be a mixed integer non-convex non-linear program for which branch and bound solution framework is guaranteed to solve the problem. Branch and bound (BnB) can be also used to obtain sub-optimal solutions with desired quality. Even though branch and bound is guaranteed to find the optimal solution, the computational cost could be extremely high, which is why we considered different types of enhancements to BnB. Mainly, we consider reformulations by linearizing a specific set of quadratic constraints in the derived formulation, as well as the application of different branching techniques to find the one that performs the best. Based on the conducted numerical experiments, it was concluded that linearization, applied for at least 100 presolving rounds, and cloud branching achieve the best performance.

Performance Analysis of Radio over Fiber Simulation Model using DPSK Modulation Technique

In this paper, performance analysis of radio over fiber (ROF) system has been proposed to analyze the performance of the system using differential phase shift keying method. RoF Systems exhibits the unique characteristic of combining the featuring of fiber optic link and free space radio path which brings many advantages and challenges to new mobile networks. RoF systems has the provision of large bandwidth and has fewer losses for the transmission that make the ROF suitable for the future wireless broadband services and fulfill demands of high data rate. The proposed simulation model helps in improving the system capacity and their effects on the output in terms of Q factor, minimum BER is analyzed by using optisystem software.

New Zealand Consumer Interest Growing for 5G Mobile

This paper summarizes results from a survey of the New Zealand mobile market by Venture Insights in October 2018. The survey had over 1,000 respondents, all of whom were responsible for making their mobile purchasing decisions, with a representative spread across New Zealand, all adult age groups, and customers from the three major mobile service providers. The survey identified a strong consumer interest in and awareness of 5G, with 31% of respondents willing to consider a move to 5G within two years of launch. Mobile video will be a strong driver, with 69% of respondents having viewed video on their mobile and, again, a willingness to move to 5G within two years. Fixed wireless broadband service was also strongly supported, with 18% of those with a household fixed broadband service indicating a possible transition within two years to a 5G fixed wireless service. However, the Ultra-Fast Broadband fixed service is likely to be a strong competitor to fixed wireless broadband.

Communication-Free Inter-Operator Interference Management in Shared Spectrum Small Cell Networks

Emergence of shared spectrum, such as the 3.5-GHz citizen broadband radio service (CBRS) band in the U.S., promises to broaden the mobile operator ecosystem and lead to proliferation of small cell deployments. We consider the inter-operator interference problem that arises when multiple small cell networks access the shared spectrum. Towards this end, we take a novel communication-free approach that seeks implicit coordination between operators without explicit communication. The key idea is for each operator to sense the spectrum through its mobiles to be able to model the channel vacancy distribution and extrapolate it for the next epoch. We use reproducing kernel Hilbert space kernel embedding of channel vacancy and predict it by vector-valued regression. This predicted value is then relied on by each operator to perform independent but optimal channel assignment to its base stations taking traffic load into account. Via numerical results, we show that our approach, aided by the above channel vacancy forecasting, adapts the spectrum allocation over time as per the traffic demands and more crucially, yields as good as or better performance than a coordination-based approach, even without accounting the overhead of the latter.

Deep Learning Classification of 3.5 GHz Band Spectrograms with Applications to Spectrum Sensing.

In the United States, the Federal Communications Commission has adopted rules permitting commercial wireless networks to share spectrum with federal incumbents in the 3.5 GHz Citizens Broadband Radio Service band. These rules require commercial systems to vacate the band when sensors detect radars operated by the U.S. military; a key example being the SPN-43 air traffic control radar. Such sensors require highly-accurate detection algorithms to meet their operating requirements. In this paper, using a library of over 14,000 3.5 GHz band spectrograms collected by a recent measurement campaign, we investigate the performance of thirteen methods for SPN-43 radar detection. Namely, we compare classical methods from signal detection theory and machine learning to several deep learning architectures. We demonstrate that machine learning algorithms appreciably outperform classical signal detection methods. Specifically, we find that a three-layer convolutional neural network offers a superior tradeoff between accuracy and computational complexity. Last, we apply this three-layer network to generate descriptive statistics for the full 3.5 GHz spectrogram library. Our findings highlight potential weaknesses of classical methods and strengths of modern machine learning algorithms for radar detection in the 3.5 GHz band.

GreenLoading: Using the citizens band radio for energy-efficient offloading of shared interests

Cellular networks are susceptible to being severely capacity-constrained during peak traffic hours or at special events such as sports and concerts. Many other applications are emerging for LTE and 5G networks that inject machine-to-machine (M2M) communications for Internet of Things (IoT) devices that sense the environment and react to diurnal patterns observed. Both for users and devices, the high congestion levels frequently lead to numerous retransmissions and severe battery depletion. However, there are frequently social cues that could be gleaned from interactions from websites and social networks of shared interest to a particular region at a particular time. Cellular network operators have sought to address these high levels of fluctuations and traffic burstiness via the use of offloading to unlicensed bands, which may be instructed by these social cues. In this paper, we leverage shared interest information in a given area to conserve power via the use of offloading to the emerging Citizens Broadband Radio Service (CBRS). Our GreenLoading framework enables hierarchical data delivery to significantly reduce power consumption and user fairness variation and includes a Broker Priority Assignment (BPA) algorithm to select data brokers for users. With the use of in-field measurements and web-based Google data across four diverse U.S. cities, we show an order of magnitude power savings via GreenLoading over a 24-hour period, on average, and power savings up to 97% at peak traffic times. Finally, we consider the role that a relaxation of wait times can play in the power efficiency of a GreenLoading network.

Combined triple band circularly polarised and compact UWB monopole antenna

A new design of a compact ultra-wide band (UWB) monopole antenna with triple-band, triple-sense circular polarisation (CP) is presented here. It is composed of a compact quad-circular monopole, a fractal parasitic ring resonator, a triangular ring resonator, rectangular ring resonator, and modified `T' and `I' shaped slots on the ground plane along with a rectangular stub with `E'-shaped slot on the right side of the monopole. The proposed antenna radiates left-hand circularly polarised (LHCP) wave at lower and mid-frequency bands, while right-hand circularly polarised (RHCP) wave at upper frequency band. The results show that the antenna covers an ultra-wide bandwidth from 3.1 to 11 GHz (112%). Moreover, the proposed antenna achieves good CP characteristics at Citizens Broadband Radio Services in USA (3.55-3.72 GHz), artificial magnetic conductors and WLAN upper frequency spectrum (4.81-5.61 GHz), VSAT services & Satellite Communication and Ground Surveillance RADAR (9.29-10.95 GHz), respectively. Novelty of this article lies in designing a compact printed UWB monopole antenna with combined triple band CP characteristics controllable by adjusting the antenna design parameters. The simulated and measured results of the antenna have been compared and seen to be in reasonable agreement.

The Wireless Threat to Fixed Broadband Services

This paper provides results from a survey of broadband customers in Australia in November 2017. Respondents included both NBN customers and non-NBN broadband customers. The survey showed an increasing acceptance of mobile broadband, in line with other market trends, but identified significant dissatisfaction – one quarter of mobile broadband respondents and about one third of fixed broadband respondents – with current services. Factors that may affect a decision to switch from fixed to mobile broadband, or vice versa, included price, reliability, bundling of phone with broadband, and the capability of streaming video on demand. Negative perceptions of the NBN are also significant. Overall, we identify that about 30% of existing fixed broadband households would consider switching to a wireless broadband service. We also note the future rollout of 5G wireless service and the resultant market positioning of telcos, which may support further positive perceptions of wireless broadband.

Maritime Networking: Bringing Internet to the Sea

Maritime networks establish wireless multi-hop networks to provide wireless broadband service at sea, connecting various kinds of ships, maritime buoys, and beacons. The maritime networks possess two distinguishing characteristics highly affected by maneuver at sea-dynamic link quality and bandwidth constrained, and dynamic network topology-that warrant specific attention. Unlike land vehicles, maneuver at sea is affected by sea surface movement and wave occlusions, which can cause unstable environment with a high rate of link breakages caused by low link stability, as well as low and highly variable bandwidth. In spite of the need to achieve performance close to high-speed terrestrial wireless broadband service on land, there is only a perfunctory effort to investigate maritime networks. There is an urgent need to refresh the interest to investigate, as well as to further enhance, maritime networks. This paper presents a review of the limited research works of this topic, which revolve around the networking issues in the link, network, and upper layers, in the literature. The objective is to establish a foundation in order to motivate a new research interest in maritime networks. Open issues are also presented to foster new research initiatives in this burgeoning and exciting area.

Coordinated Spectrum Allocation and Coexistence Management in CBRS-SAS Wireless Networks

Since the introduction of the idea of cognitive radio, various approaches towards spectrum sharing have been considered, for example, the Licensed Shared Access (LSA), which is considered in Europe, or Citizens Broadband Radio Service (CBRS) with Spectrum Access System (SAS) regulated by the US. This paper deals with the problem of coordinated resource allocation among a set of available base stations. A detailed definition of the problem is provided, followed by a discussion on a set of heuristics proposed for solving the problem. Four solutions are presented that are based on existing standards as well as on the approaches described in the literature. Next, new multi-selection (multi-choice) algorithm is proposed and discussed in detail. The main problem is divided in two subproblems, which are solved by using graph theorem and analytical description. The performance of the proposed solutions is analyzed in various scenarios. Finally, a trade-off between power allocation and frequency use is provided. All challenges identified during the investigation of the problem are presented.

Resource Allocation in Moving and Fixed General Authorized Access Users in Spectrum Access System

Spectrum access system (SAS) is a spectrum sharing framework proposed to share the spectrum between the incumbent users and the citizen broadband radio service devices, i.e. Priority access users and general authorized access (GAA) users. In this paper, we propose an interfering angle based method for the joint resource (channel and transmit power) allocation problem to the mobile and fixed GAA users. With mobile GAA users, the set of GAA users that can hear each other will change at different time instants making the resource allocation problem more challenging. The resource allocation of fixed and mobile GAA users is done considering coexistence with priority users, as well as coexistence between mobile and fixed GAA users. For the conflict-free resource allocation to fixed and mobile GAA users, we propose to use the maximum allowed transmit power for the beams of fixed GAA users that lie within the interference range of mobile GAA users. The simulation results show improved capacity from our proposed method while satisfying a predetermined interference constraint.

Spectrum Management Application for Virtualized Wireless Vehicular Networks: A Step Toward Programmable Spectrum Management in Future Wireless Networks

Spectrum management is a key challenge in the domain of wireless network virtualization. An efficient tool is needed to support dynamic, yet policy-compliant allocation of the frequency resources in virtual networks. In this article, we discuss the idea of a spectrum management application (SMA) as a tool for solving this technoeconomic issue in virtualized networks. The generic idea is exemplified in the application of the Citizen Broadband Radio Service (CBRS) model for spectrum sharing, and it has been tested in field trials with real operating networks. The results of this study show that the fully automated allocation of frequency resources, following the rules provided by the SMA, may be used for better spectrum utilization, while preserving the quality of all managed networks. This result may be treated as an important step toward efficient network management in a virtualized wireless networks.

Online Algorithm for Leasing Wireless Channels in a Three-Tier Spectrum Sharing Framework

The three-tier spectrum sharing framework (3-TSF) is a spectrum sharing model adopted by the Federal Communications Commission. According to this model, under-utilized federal spectrum like the Citizens Broadband Radio Service band is released for shared use where the highest preference is given to Tier-1 followed by Tier-2 (T2) and then Tier-3 (T3). In this paper, we study how a wireless operator, who is interested in maximizing its profit, can strategically operate as a T2 and/or a T3 user. T2 is characterized by paid but ”almost” guaranteed and interference-free channel access while T3 access is free but has the lesser guarantee and also faces channel interference. So the operator has to optimally decide between paid but better channel quality and free but uncertain channel quality. Also, the operator has to make these decisions without knowing future market variables like customer demand or channel availability. The main contribution of this paper is a deterministic online algorithm for leasing channels that has finite competitive ratio, low time complexity, and that does not rely on the knowledge of market statistics. Such algorithms are desirable in the early stages of the deployment of 3-TSF because the knowledge of market statistics may be rather inaccurate. We use tools from the ski-rental literature to design the online algorithm. The online optimization problem for leasing channels is a novel generalization of the ski-rental problem. We, therefore, make fundamental contributions to the ski-rental literature, the applications of which extend beyond this paper. We also conduct simulations using synthetic traces to compare our online algorithm with the benchmark and state-of-the-art algorithms.

Utilization and Balance in Channel Assignment for Rural Wireless Mesh Networks

Wireless mesh networks with directional antennas are expected to be a new promising technology and an economic approach for providing wireless broadband services in rural areas. In these networks, the effective use of multiple non-overlapping channels can significantly enhance the network capacity by allowing more concurrent transmissions. However, the performances of wireless mesh networks are severely degraded by interference between links with overlapping channels in nearby areas. In this paper, we address the issue of joint utilization and balance in channel assignment for rural wireless mesh networks. We design a new channel assignment framework with the goal of optimizing the channel resource utilization across the entire network while taking balanced allocation into account. This balanced channel assignment allows for the cost-effective reuse of channels without a consequent loss of quality in the rural wireless mesh networks. We also evaluate the proposed framework on some Cartesian product graphs that are popular interconnection network topologies. The framework guarantees that these topologies require a small number of channels for balanced allocation.

Reduced-Power Almost Black Subframe Based Pulse Radar Spectrum Sharing for LTE System

Cochannel pulse radar and long term evolution (LTE) deployments are considered by the FCC citizen broadband radio service (CBRS) and also 5G spectrum sharing. This paper proposes a radar spectrum sharing method based on LTE reduced-power almost blank subframe (RP-ABS) mechanism, which is used to mitigate interference to pulse radar while maintaining high LTE throughput. For LTE, payload bits are first packed into nonradar interfered time domain subframes (SFs), and then RP-ABS or even zero-power almost blank subframe (ABS) are adopted in the rest SFs. For pulse radar, target detection performance is guaranteed, thanks to the decreased interference caused by LTE RP-ABS power. We also formulate and solve an optimization problem for radar and RP-ABS-based LTE spectrum sharing, which consider tradeoffs between RP-ABS-based LTE performance (bit error rate and throughput) and radar detection probability concurrently. Using 3rd generation partnership project (3GPP) LTE sensitivity test as a benchmark, 28.83% throughput gain can be obtained for RP-ABS-based method. A hardware-in-the-loop testbed is also designed to prove spectrum sharing between RP-ABS-based LTE and radar viable.

Two-Stage Rate Allocation Game in Wireless Access Networks With PON Backhaul

To support the increasing demand for the mobile broadband service by a massive number of users, the 5G communication standard facilitates the convergence of wireless access networks with backhauling supported by the passive optical network. A key challenge of this type of converged network architecture is the distribution of bandwidth or data rate from the central office to the different mobile operators providing wireless broadband services at access networks and then to the end users. This letter investigates the application of a novel pricing-based rate allocation scheme using two-stage Stackelberg competition on an optical-wireless hybrid network architecture considering the users’ satisfaction level and pricing affordability. Numerical calculations have been carried out for one specific network scenario to study the data-rate distribution and the behavior of utilities of different network entities with the variation of different parameters.

Code shift keying based joint radar and communications for EMCON applications

Due to the explosion in the demand for broadband wireless services by consumers, wireless network service providers require increased frequency allocations from an already crowded frequency spectrum. In an effort to satisfy the increased frequency spectrum requirements of wireless communications networks, several methods have been proposed to allow communication systems and radars to co-exist within the same bandwidth or adjacent frequency bands while minimizing or preventing mutual interference. Most methods explored in the literature focus on the use of cognitive sensing and dynamic spectrum allocation. Other proposed methods to prevent mutual interference between radar and communications systems focus on waveform design. In this manuscript, a dual function communication and radar system with EMCON applications is investigated that uses Gold or Kasami codes in a code shift keying digital modulation scheme. The use of both binary phase shift keying (BPSK) and quaternary phase shift keying (QPSK) to modulate the code bits is investigated. The communications signal is used as the radar signal to implement a pseudo-random BPSK or QPSK coded radar. The symbol error rate (SER) of the communication system is determined through Monte Carlo simulations and compared to an SER upper bound for M-ary frequency shift keying. The radar signal's periodic autocorrelation function (PACF) and periodic ambiguity function are also examined demonstrating the schemes potential for use in a low probability of intercept radar application. The radar signal's characteristics are compared when using pseudo-random BPSK and QPSK modulations.

Efficient MAI Cancellation Scheme in MC-DS-CDMA Using SIC

As of late, the group of multi carrier direct sequence code division multiple access (MC-DS-CDMA) transmission technologies has drawn a considerable measure of consideration in giving broadband wireless communication services. It stands as a promising procedure to help multiple clients with secured high speed wireless communications. In any case, the limit of the MC-DS-CDMA is restricted via multiple access interference (MAI) as of different clients and furthermore it influences the CDMA frameworks performance. To beat such disadvantage, a proficient wireless transmission plot that mitigates the MAI for dual tree complex wavelet transform centered MC-DS-CDMA frameworks is proposed by this given paper. In the proposed conspire, total mean square error equalizer is utilized to presents the initial appraisal of clients’ data and the successive interference cancellation plot is after that utilized to regenerate and call off the MAI from the desired client. In this proposed scheme, MAI is revived; subsequently as of the signal that was received it is subtracted in time domain ahead of equalization. The proposed system successfully maintains a deliberate distance from the MAI and also enhances the limit is revealed in experimental outcomes.

Fuzzy-Estimation Control for Improvement Microwave Connection for Iraq Electrical Grid

The demand for broadband wireless services is increasing day by day (as internet or radio broadcast and TV etc.) for this reason and optimal exploiting for this bandwidth may be other reasons indeed be there is problem in the communication channels. it’s necessary that exploiting the good part form this bandwidth. In this paper, we propose to use estimation technique for estimate channel availability in that moment and next one to know the error in the bandwidth channel for controlling the possibility data transferring through the channel. The proposed estimation based on the combination of the least Minimum square (LMS), Standard Kalman filter, and Modified Kalman filter. The error estimation in channel use as control parameter in fuzzy rules to adjusted the rate and size sending data through the network channel, and rearrangement the priorities of the buffered data (workstation control parameters, Texts, phone call, images, and camera video) for the worst cases of error in channel. The propose system is designed to management data communications through the channels connect among the Iraqi electrical grid stations. The proposed results show that the modified Kalman filter have a best result in time and noise estimation (0.1109 for 5% noise estimation to 0.3211 for 90% noise estimation) and the packets loss rate is reduced with ratio from (35% to 385%).

Modelling the Impact of Spectrum Sharing on Spectrum Value: The US Citizen Broadband Radio Service Ecosystem

In 2015, the US Federal Communications Commission released a Report and Order to enhance the availability of spectrum across the nation with a particular focus on wireless broadband services.The decision consisted of designating the 3.5 GHz band (3550 to 3700 MHz) as a three-tiered spectrum sharing space, knows as Citizens Broadband Radio Service (CBRS). The tiers are occupied by incumbent users in the upper tier (mainly federal aeronautical uses and non-federal fixed satellite services and terrestrial wireless operations), new entities known as Priority Access Licensees (PALs) on the middle tier, and a non-licensed access mode called General Authorised Access (GAA) on the bottom tier. Fast, and seemingly chaotic, technological progress and the pressing interests from stakeholders demand a closer, sharper consideration of an integral approach to determining the value of the spectrum. The assumptions in this paper rely strongly on stating that the goal of efficient spectrum management is to maximize the social and economic value of spectrum subject to conditions and constraints set by policy makers, possible via a spectrum authority. The proposed US 3.5 GHz ecosystem, or CBRS, provides a rich structure that allows for an assessment of spectrum value distribution among the ecosystem actors and uses. Building upon recent work in the UK that proposes three components for spectrum value, namely private use value, private external use value, and broad social value, our paper presents and discusses a descriptive model of spectrum value aimed to investigate the effects of spectrum sharing on the value of spectrum perceived by the players sharing the band. The short story of utilization of the upper part of the 3.5 GHz band by Wireless Interent Service Providers, or WISPs, in the US, and the spectrum regulatory changes occurred over the last 10 years are used to exemplify the complex arrangements that need to be considered in order to assess the value of spectrum. The case reveals the importance of using the above mentioned three components of value. The fact that no definitive clear boundaries can be defined between the value components adds to the complex task of assessing how valuable spectrum is and how changes to permitted uses affect its value. Currently divergent interests clash over what pathway to regulatory conditions must be adopted for tier-2 PALs. The struggle centers on the license terms and auction conditions. Currently PALs would be allocated via an auction in census tract areas if there is enough competition; upon assignment, a PAL would get 3-year licenses with no assurance for renewal. Big telecommunications companies, thirsty for more spectrum capacity for 5G services, want longer terms with assurance of renewal, a change from census tracts to larger “Partial Economic Areas”, and the abolition of “enough competition” for PAL assignment so that even when there is only one license seeker, the FCC will have to grant a license. In a new notice of consultation the FCC is also considering hybrid solutions that might allow combinations of such competing terms to apply to different geographical areas. Our model of value allows us to understand not only how value is distributed across the CBRS but also how the proposed changes may affect such distribution, hence the social and economic goals expected from the 3.5 GHz ecosystem.