Non-real Time Research Articles

Maximization of user satisfaction in OFDMA systems using utility‐based resource allocation

AbstractIn order to keep and/or expand its share of the wireless communication market and decrease churn, it is important for network operators to keep their users (clients) satisfied. The problem to be solved is how to increase the number of satisfied non‐real time (NRT) and real time (RT) users in the downlink of the radio access network of an orthogonal frequency division multiple access system. In this context, the present work proposes a method to solve the referred problem using a unified radio resource allocation (RRA) framework based on utility theory. This unified RRA framework is particularized into two RRA policies that use sigmoidal utility functions based on throughput or delay and are suitable for NRT and RT services, respectively. It is demonstrated by means of system‐level simulations that a step‐shaped sigmoidal utility function combined with a channel‐aware opportunistic scheduling criterion is effective toward the objective of user satisfaction maximization. Copyright © 2014 John Wiley & Sons, Ltd.

Analysis of transboundary Dojran Lake mean annual water level changes

Dojran Lake located in south-eastern part of the Balkan is shared by Macedonia and Greece. This valuable water body and its ecosystem are vulnerable both to climate and anthropogenic impacts. Within the period 1988–2002, the Dojran Lake water level decreased seriously (6 m) and the littoral zone of the lake became dry. This water level decline together with the simultaneous water quality deterioration resulted in a biodiversity diminish and plankton reduction. The attack on the ecosystem had a harmful impact on the economy in the region. In the last decade, the water increasing trend of the lake water level has been observed. How much the lake is impacted by natural climatic causes, and how much by human activities in the watershed, is a question that cannot be answered easily. The main obstacle for Dojran Lake sustainable water resources management is the fact that there is no exchange of data and information between Greece and Macedonia. Hydrological analysis is obtained using data measured for the period 1951–2010 at the meteorological and hydrological Nov Dojran gauging stations located on the Macedonian side. The aim of the paper is stimulation of a close international interdisciplinary monitoring and cooperation. Of crucial importance is to facilitate the free and unrestricted exchange of data and information, products and services in real and non-real time on matters relating to the safety and security of society, economic welfare and the protection of Dojran Lake environment.

Optimized Network Selection Using Aggregate Utility Function in Heterogeneous Wireless Networks

To provide global connectivity with high speed and high quality at any place and any time is now becoming a reality due to the integration and co-ordination of different Radio Access Technologies(RAT) such as Worldwide Interoperability for Microwave Access (WiMAX), Universal mobile Telecommunication Systems (UMTS), Wireless Local Area network (WLAN) and Long Term Evolution (LTE).Such a diversity of networks offers different choices in terms of bandwidth, security, cost, latency and the coverage area for the mobile user. For such a heterogeneous wireless environment, it is important to design an intelligent handover algorithm which selects the optimal target network. The existing works do not consider the interdependence between the criteria and the use of application QoS in weight calculation during network evaluation process. To address this issue, an appropriate multicriteria network selection algorithm based on multiplicative weighted utility function is proposed to provide complete solution for seamless connectivity in heterogeneous environment based on network conditions, application QoS, Mobile Terminal (MT) battery level and user preferences. MATLAB based simulations are conducted to highlight the effectiveness of proposed scheme and simulation results confirm that the proposed scheme selects the best suitable network for both Real-Time (RT) and Non- Real Time (NRT) applications while achieving optimization between QoS, cost and energy consumption. The Cobb-Douglas based user satisfaction degree is also estimated to verify whether the selected network maximizes the end user satisfaction for the offered service.

Performance Analysis of a Prioritized Multilevel Access Allocation Scheme for Data Calls in GSM Networks

The demand of voice and data services on the Global System for Mobile Communications (GSM) is unprecedented in the annals of the history of telecommunication systems. As a result, grade of service (GoS) is no longer stable in the face of this high demand. This paper explores the use of prioritized multilevel Access Allocation (PMAA) scheme to stem the instability of data services when there is high demand. This paper classifies calls into Handover (HD), Real-Time (RT) and Non-Real-Time (NRT) based on the nature of their service and thereafter, priority was set among them. The HD has the highest priority followed by RT and NRT respectively. The channels in the cell were partitioned into three pools named as q1 , q2 , and q3. Data and voice calls have different characteristics, therefore, voice always have priority over data since it cannot tolerate delay in call processing. The q1 is reserved for voice only, q3 reserved for data only while q3 is reserved for handoff calls for both voice and data.

Energy-saving centric uplink scheduling scheme for broadband wireless access networks

Abstract This study proposes an energy-saving centric uplink scheduling (ESC-US) scheme to support efficient energy usage and satisfy the quality of service (QoS) requirements of Worldwide Interoperability for Microwave Access (WiMax) networks. The uplink resource allocation is different from that of the downlink resource allocation scheme because the uplink traffic is queued at the mobile station (MS) and the base station (BS) has no information regarding it without using a polling procedure. The considered resource scheduling schemes maximize the sleep efficiency and consider the QoS requirements of individual MSs. The proposed scheduling scheme in this study considers the delay budget of MSs with real-time connections and the required minimum reserved traffic rate (MRTR) of MSs with non-real time connections when maximizing sleep efficiency. Both scheduling schemes for the traffic of real-time polling services (rtPS) and non-real-time polling services (nrtPS) apply the ‘just enough QoS’ and ‘sleep before transmission’ (SbT) concepts to achieve this energy-saving centric objective. Exhaustive simulations were conducted to examine the performance of the proposed schemes. The simulation results show that both schemes guarantee the desired QoS and achieve superior energy-savings efficiencies compared to the conventional scheme.

Traffic Priority Based Adaptive and Responsive Congestion and Rate Control for Wireless Mesh Networks

Congestion Control in Wireless Mesh Networks (WMNs) has been a widely studied context oriented utilization maximization problem. The traffic in WMNs has a wide range of variations (i.e. bandwidth, jitter, delay jitter sensitive applications) due to its use as the backbone network for accessing Internet. Eventually, traffic variation contributes to channel saturation and may bring up congestion due to contention caused by concurrent transmission, buffer overflows and time varying wireless channel condition. In this paper, we propose a distributed congestion control scheme for wireless mesh networks to ensure higher network throughput while avoiding congestion and maintaining inter-flow fairness where real time and non-real time traffic coexists. Our proposed technique handles congestion by restricting the available transmission rate of downstream nodes among the upstream nodes according to their flow demands based on three basic parameters: packet arrival rate, service rate and buffer occupancy. We also introduce prioritized queues in each node to treat real time and non-real time traffic differently. Therefore, congestion degree calculation, rate allocation and prioritizing traffic ensures higher network throughput and guaranteed delivery of real time traffic. Experiments conducted on ns-2 simulations demonstrate that our proposed algorithm can achieve significant improvements in both overall network throughput and inter-flow fairness for both non real time and delay bound traffic.

Performance Analysis of Scheduling Mechanisms in WiMAX Networks

The IEEE 802.16 standard for broadband wireless metropolitan area network supports real time and non-real time services. It has a provision to design new packet scheduling algorithms based on the requirements to support Quality of Service (QoS) for all type of traffic. Several scheduling algorithms are available in the literature for inter-class and intra-class scheduling. In this paper, scheduling algorithms like Earliest Deadline First (EDF), Weighted Fair Queuing (WFQ) and Deficit Weighted Round Robin (DWRR) are implemented for intra-class scheduling. Performances are analyzed in terms of Delay, Packet Loss and Throughput. The results illustrate that EDF provides better QoS for traffic with variable sized packets.

On a near-optimal control approach for a wave energy converter in irregular waves

Real-time smooth reactive control and optimal damping of wave energy converters in irregular waves is difficult in part because the radiation impulse response function is real and causal, which constrains the frequency-dependent added mass and radiation damping according to the Kramers–Kronig relations. Optimal control for maximum energy conversion requires independent synthesis of the impulse response functions corresponding to these two quantities. Since both are non-causal (one being odd and other even), full cancellation of reactive forces and matching of radiation damping requires knowledge or estimation of device velocity into the future. To address this difficulty and the non-causality of the exciting force impulse response function, this paper investigates the use of propagating-wave surface elevation up-wave of the device to synthesize the necessary forces. Long-crested waves are assumed, and the approach is based on the formulations of Naito and Nakamura [2] and Falnes [22]. A predominantly heaving submerged device comprised of three vertically stacked discs driving a linear power take-off is studied. The overall formulation leads to smooth control that is near-optimal, given the approximations involved in the time-shifting of the non-causal impulse response functions and the consequent up-wave distances at which wave surface elevation is required. Absorbed power performance with the near-optimal approach is compared with two other cases, (i) when single-frequency tuning is used based on non-real time adjustment of the reactive and resistive loads to maximize conversion at the spectral peak frequency, and (ii) when no control is applied with damping set to a constant value. Simulation results for wave spectra over a range of energy periods and significant wave heights are compared for the three situations studied. While practical implementation presents engineering challenges, in terms of time-averaged absorbed power, unconstrained near-optimal control is found to perform significantly better than single-frequency tuning in the spectra with longer energy periods (>10s for the present device), and somewhat better in the spectra with shorter energy periods (here ≤10s).

Performance approximations and bounds for non‐real‐time traffic in an integrated service system

The authors consider an integrated service system, where real-time (RT) calls of multiple rate requirements and non-real-time (NRT) calls share the total system capacity. Typically, RT calls are given strict priority over NRT calls; therefore NRT performance is dependent on the RT process. When RT call arrivals do not follow a Poisson process, the effect of the RT traffic burstiness on the NRT performance has not been investigated. In this study, the authors investigate this effect and provide computationally efficient approximations and bounds for the NRT performance evaluation in the integrated service system with multi-rate non-Poisson RT traffic. With known first and second moments of the RT call arrival processes, the authors propose to consider the multi-rate non-Poisson RT traffic streams as an equivalent single-rate Poisson traffic stream. Then, the authors evaluate the NRT performance by converting the original system to a system offered with the equivalent RT traffic and the NRT traffic. The authors’ approximations and bounds are validated by extensive numerical examples.

Enhancing QoS Through Dynamic and Fare AP Selection in a Wireless LAN

The IEEE 802.11 WLAN is primarily used for web browsing which belongs to the category of nonreal time application. But the demand of real time applications like VOIP and video conferencing has become very much common to such WLAN. With IEEE 802.11e Mac protocol it is possible to improve the QoS for both real and non-real time traffic by service differentiation. To ensure efficient utilization of the radio resources and enhanced QoS the load imbalance should be resolved among APs from different BSSs. In large scale WLAN inter AP communication mechanism can be employed along side the current admission controller under EDCA. Beside service differentiation inter AP differentiation based QoS management can lead to efficient utilization of radio resources by moving STAs from heavily laded to a less loaded AP and ensure better QoS for all types of traffics. In this paper we propose a dynamic and fair AP selection mechanism to improve the QoS in a WLAN. The simulations have been carried out with NSv2.34. Index Terms — EDCA, QoS, Contention Window, VoIP, AC.

Collaborative Pharmacy Student Learning Outline for Mobile Atmosphere

the idea of this research is for the concern of Collaborative learning based mobile factors by applying via pharmacy students of the college. We focus on three features, computer mutual learning, learning process module, and student learning mode. In this paper, student-focused instruct module, student edge section, teacher interface section, learner section, solution problem section, curriculum section, control section, and diagnose section are planned. This system permits students to be sustained with a real time approach, non-real time approach, mixture approach. The devices used contain smart phone, PDAs, mobile devices, transportable computers and tablet PDAs. This system is to become a more capable student learning environment so that student can get student’s learning done more efficiently. The development of a collaborative learning combines the advantages of an adaptive learning environment with the advantages of mobile telecommunication and the suppleness of mobile devices.

Analysis of a Cellular Network Model with Multiparameter Control for Call Admission to Channels and to Data Call Buffer1

A numerical method is proposed to calculate the quality of service (QoS) of multi-service cellular networks with multi-parameter call admission control. A finite or infinite queue for non-real time traffic only is allowed. A decision for the access of new and handover voice calls is chosen on the basis of the number of such calls in channels while appropriate decision for handover data calls depend on the total number of such calls in the buffer.

Statistically controlled opportunistic resource block sharing for femto cell networks

In this paper, we propose an efficient interference management technique which controls the number of resource blocks (or subcarriers) shared with other cells based on statistical interference levels among cells. The proposed technique tries to maximize average throughput of a femto cell user under a constraint on non-real time control of a femto cell network while guaranteeing a target throughput value of a macro cell user. In our proposed scheme, femto cells opportunistically use resource blocks allocated to other cellsif the required average user throughputis not attained with the primarily allocated resource blocks. The proposed method is similar to the underlay approach in cognitive radio systems, but resource block sharing among cells is statistically controlled. For the statistical control, a femto cell sever constructs a table storing average mutual interference among cells and periodically updates the table. This statistical approach fully satisfies the constraint of non-real time control for femto cell networks. Our simulation results show that the proposed scheme achieves higher average femto user throughput than conventional frequency reuse schemes for time varying number of users.

Detection of offshore ship and well platform based on optical remote sensing images

To improve situations as follows: in the strategies of offshore ship and well platform detection,most masks of sea zones use non-real time shoreline database;targets seeking algorithms lack capability of searching targets in large scale images,a strategy of ship and well platform detection based on optical remote sensing images was proposed.The strategy included building masks of sea zones using morphological operations,determining decision algorithms of targets' existence,and extracting targets' locations based on iterative optimal Threshold Segmentation(TS) in Sliding Windows(SW).Parameters in the decision algorithm and the size of sliding window were analyzed,and the corresponding results were cross validated with that of artificial visual interpretation.The experimental results prove that the absolute accuracy of targets extraction arrives 0.981 while relative accuracy of targets extraction arrives 0.954 with proper parameters set.This strategy shows practical value.

다중 홉 해양통신망에서 실시간 통합 서비스를 위한 MAC 프로토콜

In this paper, we propose a new frame structure and the underlying dynamic resource control mechanism to support an integrated service, including a real-time (RT) service that requires to serve the end-to-end delay performance, as well as non-real-time (NRT) service, using Self-Organizing Time Division Multiple Access (SO-TDMA)-based MAC protocol in a multi-hop ad-hoc maritime communication network. The underlying frame structure is dynamically configured by resource allocation to guarantee the average target outage performance of the real-time service. Toward this end, we analyze the average outage probability and its performance is verified for the proposed frame structure by simulation.

A Survey on Routing Protocols in Wireless Multimedia Sensor Networks

ABSTRACT The recent technological advances in micro electromechanical systems have promoted the development of a powerful class of sensor-based distributed intelligent systems capable of ubiquitously retrieving multimedia information, namely Wireless Multimedia Sensor Networks (WMSNs). WMSNs are gaining more popularity day by day as they are envisioned to support a large number of both non-real time and real-time multimedia applications. In this paper, current state-of-the-art in energy-efficient routing techniques for WM-SNs is surveyed together with the highlights of the performance issues of each strategy. This paper outlines the design challenges of routing protocols for WMSNs. Architectures for WMSNs are explored, along with their advantages and drawbacks. Further, a classification of recent routing protocols for WMSNs and a discussion of possible future research trends are presented. General Terms Your general terms must be any term which can be used for general classification of the submitted material such as Pattern Recognition, Security, Algorithms et. al.

Study analysis of Cross QoS based Scheduler for 3.9G LTE Network

The proposed algorithm prolongs the scheduler from scheduling the Real Time (RT) and Non Real Time (NRT) services based upon their priority required on Quality of Service (QoS). The proposed Cross QoS Scheduling Algorithm (XQSA) is capable of scheduling data, video and voice services over the same wireless channel. The complimentary advantages of both RT (video & voice) and NRT (Best Effort of service, BE) services and cross layering technology is utilized by XQSA which prioritizing services in the scheduler to achieve a significant cell user throughput, a low delay, normalized fairness and a low packet loss ratio. The XQSA adapted the two different scheduling principles together to govern the effective channel utilization. The simulation of the XQSA under multiple cell scenarios for scheduling in the 3.9G LTE (Long Term Evolution) network is done using LTE-Sim tool. In the XQSA policy, the traditional RT and NRT scheduling algorithm are integrated together to support the multi-service scheduling (i.e., Modified Long Weighted Delay First/Proportional Fair (M_LWDF/PF) & Exponential Proportional Fair/Proportional Fair (EXP_PF/PF)). The study analysis of the XQSA is examined experimentally through simulation in terms of throughput, packet loss ratio, delay and cell spectral efficiency and fairness index. The simulation based comparison indicates that M_LWDF/PF and EXP_PF/PF scheduler outperforms PF scheduler especially during RT service. The PF scheduler has high throughput for the NRT service. In all the simulations, the performance level of EXP_PF/PF scheduling algorithm for multi-service scheduling seems to be an optimal solution for guaranteeing required QoS (Quality of Service). Index Terms—Channel Quality Indicator (CQI), Channel Utilization, Cross Layering, Cross QoS Scheduling Algorithm (XQSA), 3.9G, LTE- Sim, LTE, Multi-service scheduling, Quality of Service (QoS), Spectral Efficiency, User's Fairness. ——————————  ——————————

Multi-path Stable QoS Routing for Real-time Traffic Applications in MANET

mobile ad hoc networks (MANET), the existing routing protocols consider the routing metrics such as bandwidth, delay and link stability in partial manner. Also the real time and non- real time traffic flows are not distinguished based on delay and bandwidth requirements. In order to overcome these issues, in this paper multipath stable QoS routing for real time traffic in MANET is proposed. In this technique, multiple paths are discovered among source and destination. Among the discovered routes, the optimal paths are selected based on bandwidth constraints, delay constraints and path stability. When any flow request is received, it is initially categorized as real time and non-real time flows where real time flows are given higher priority. For real time flows, bandwidth and delay constrained paths are chosen. For non-real time flows, the stable paths are chosen. By simulation results, the proposed approach is validated and the approach minimizes delay and overhead.

QoS based Adaptive Admission Control Algorithm for Wireless Multimedia Networks

In wireless multimedia networks, the process of offering Quality of Service (QoS) guaranteed multimedia services becomes more challenging owing to the limited bandwidth, dynamic environment and mobility. This problem can be overcome by a call admission control mechanism that restricts the network access based on resource availability. In this paper QoS based Adaptive admission control algorithm for wireless multimedia networks is proposed. Initially the calls entering the network cell are categorized as real time handoff calls, non-real time handoff calls and new calls which are handled in the similar progression. In common, any call category entering the cell undergoes bandwidth test and when the bandwidth value is satisfied, the call is admitted. Otherwise cell performs different cell resizing technique for respective call categories. The proposed work is implemented in Network simulator (NS-2). It is shown that the proposed admission control algorithm achieves better bandwidth utilization, fairness with reduced call dropping rate, when compared with the existing technique. A mobile cellular architecture based on WCDMA is considered for implementation of this technique. Conclusion The proposed methodology prevents call rejection thereby avoid data losses.

Modelling of Differentiated Bandwidth Requests in IEEE 802.16m Systems

In order to support a large number of mobile stations (MSs) with statistical multiplexing in cellular networks, a random access scheme is widely used for uplink (UL) bandwidth request (BR). In the design of a random access based BR scheme, there are two important requirements: short connection delay and diverse Quality of Services (QoSs) support. Such requirements are crucial for IMT-Advanced systems like IEEE 802.16m to provide various types of fourth generation (4G) data services. IEEE 802.16m provides advanced UL BR schemes for non-real time polling service (nrtPS) and best-effort (BE) service to meet the requirements of short connection time and multiple QoS level support. In order to provide short connection time and multiple QoS support, three-step and differentiated BR procedures are adopted. In this paper, a novel modelling of IEEE 802.16m contention based BR scheme is proposed that uses a 2-dimensional discrete time Markov chain. Both the short access delay three-step BR procedures and normal five-step BR procedure are considered in the model. Our proposed model also incorporates the IEEE 802.16m differentiated BR procedure. With the proposed model, we extensively evaluate the performance of IEEE 802.16m BR for two different service classes by changing QoS parameters, such as backoff window size and BR timer. Computer simulations are performed to corroborate the accuracy of the proposed model for various operation scenarios. With the proposed model, accurate QoS parameter values can be derived for the IEEE 802.16m contention-based BR scheme.