High Bandwidth Utilization Research Articles

Decentralized Time-Synchronized Channel Swapping for Ad Hoc Wireless Networks

Time-synchronized channel hopping (TSCH) is currently the most efficient solution for collision-free interference-avoiding communications in ad hoc wireless networks, such as wireless sensor networks, vehicular networks, and networks of robots or drones. However, all variants of TSCH require some form of centralized coordination to maintain the time–frequency slotting mechanism. This leads to slow convergence to steady state and moderate time–frequency slot utilization, particularly under node churn or mobility. We propose decentralized time-synchronized channel swapping (DT-SCS), which is a novel protocol for medium access control (MAC) in ad hoc wireless networks. Under the proposed protocol, nodes first converge to synchronous beacon packet transmissions across all available channels at the physical layer, with a balanced number of nodes in each channel. This is done by the novel coupling of distributed synchronization and desynchronization mechanisms —which are based on the concept of pulse-coupled oscillators—at the MAC layer. Decentralized channel swapping can then take place via peer-to-peer swap requests/acknowledgments made between concurrent transmitters in neighboring channels. We benchmark the convergence and network throughput of DT-SCS, TSCH, and the efficient multichannel MAC protocol (seen as the state of the art in decentralized, interference-avoiding, and multichannel MAC protocols) under simulated packet losses at the MAC layer. Moreover, performance results via a Contiki-based deployment on TelosB motes reveal that DT-SCS comprises an excellent candidate for decentralized multichannel MAC-layer coordination by providing for quick convergence to steady state, high bandwidth utilization under interference and hidden nodes, as well as high connectivity.

5G mobile terminals with advanced QoS-based user-centric aggregation (AQUA) for heterogeneous wireless and mobile networks

In this paper we present an advanced QoS provisioning module with vertical multi-homing framework for future fifth generation (5G) mobile terminals with radio network aggregation capability and traffic load sharing in heterogeneous mobile and wireless environments. The proposed 5G mobile terminal framework is leading to high performance utility networks with high QoS provisioning for any given multimedia service, higher bandwidth utilization and multi-RAT capabilities. It is using vertical multi-homing and virtual QoS routing algorithms within the mobile terminal, that is able to handle simultaneously multiple radio network connections via multiple wireless and mobile network interfaces. Our 5G proposal is user-centric, targeted to always-on connectivity, maximal network utilization, maximal throughput, seamless handovers and performances improvement by using vertical multi-homing, as well as session continuity. The performance of our proposed mobile terminal framework for 5G is evaluated using simulations and analysis with multimedia traffic in heterogeneous mobile and wireless scenarios with coexistence of multiple radio access technologies, such as 3G, 4G as well as future 5G radio access networks.

Branch Effects on Channel Capacity for Broadband Power-Line Communications

In this paper, a simplified method for channel capacity estimation has been derived based on the transmission-line theory under the condition of high-bandwidth utilization. This method decouples the channel capacity into several independent components which may help to investigate the effects of backbone and branch, respectively. Analysis of backbone effects with respect to the available bandwidth reveals the applicable condition for the simplified method. Single branch effects are investigated considering branch length together with the loads. Besides, coupling effects caused by branch interactions are studied in a statistical way. The simulation results show great consistencies by using the proposed method and the conventional one and reveal the way that branches affect the channel capacity in different power networks.

Block Level De-duplication Check for Shared Data on Hybrid Cloud using Convergent Key

In regards to increase in use of digital information users prefer to store information in cloud system. In cloud storage system many users can store same type of data leading to data duplication causing a high utilization of bandwidth. Some techniques are proposed for making cloud more efficient and effective regarding to storage and bandwidth. In current time data de-duplication is effective technique to avoid such data duplication caused due to privileged as well as non-privileged user. To save bandwidth to transact data when replicating it offsite for disaster recovery huge organization, companies and all education institutes supports de-duplication technique. With the help of “Content hash keying” data confidentiality is provided. Using this technique data is first encrypted and the encrypted data is outsourced to the client. To address the problem of authorized access in our proposed system deduplication check technique is introduced and privileged access which is different from traditional data de-duplication check system. Log based approach for unauthorized data duplication check in hybrid cloud architecture is also explored. For privileged as well as for non-privileged users de-duplication can be managed using the above technique. Proposed system provides clever solution for duplication of data and also works on bandwidth efficiency.

Non-Real-Time Network Traffic in Software-Defined Networking: A Link Bandwidth Prediction-Based Algorithm

Network traffic control is the process of managing, prioritizing, controlling or reducing the network traffic by the network scheduler. High utilization of link bandwidth is very significant for network control and maintenance in Software-Defined Networking (SDN). When we get the accurate link bandwidth predictions for T time periods of the future in a specific network topology, the residual link bandwidth could be determined by the link bandwidth capacity and corresponding prediction values. Given the non-real-time request pairs, this process can be transformed into a multi-commodity flow model. But the traditional multi-commodity model has not introduced the time dimension. In this paper, the model associated with the time dimension is to complete the transmission of the non-real-time network traffic. However, in consideration of the large scale of the problem, a heuristic algorithm on the basis of greedy strategy is proposed to schedule the non-real-time network traffic properly. The experiments show that the heuristic algorithm is superior to global optimization in computing speed and the single path resulting from heuristic algorithm occupies fewer links in the network topology for the non-real-time network traffic.

Design of WDM-RoF-PON Based on Improved OFDM Mechanism and Optical Coherent Technology

In this paper, we propose a wavelength division multiplexed radio-over-fiber passive optical network (WDM-RoF-PON) based on the improved orthogonal frequency division multiplexing (OFDM) format and optical coherent technology. With OFDM and coherent receiving technology, the access network achieves high bandwidth utility efficiency and excellent transporting properties. Using optical heterodyne, the network implements 60 GHz wireless access without adding a radio source. We evaluate the performance of the system in terms of bit error rate, coverage area, and receiving constellation and obtain a network with an excellent access property.

A Survey on Quality of Experience of HTTP Adaptive Streaming

Changing network conditions pose severe problems to video streaming in the Internet. HTTP adaptive streaming (HAS) is a technology employed by numerous video services that relieves these issues by adapting the video to the current network conditions. It enables service providers to improve resource utilization and Quality of Experience (QoE) by incorporating information from different layers in order to deliver and adapt a video in its best possible quality. Thereby, it allows taking into account end user device capabilities, available video quality levels, current network conditions, and current server load. For end users, the major benefits of HAS compared to classical HTTP video streaming are reduced interruptions of the video playback and higher bandwidth utilization, which both generally result in a higher QoE. Adaptation is possible by changing the frame rate, resolution, or quantization of the video, which can be done with various adaptation strategies and related client- and server-side actions. The technical development of HAS, existing open standardized solutions, but also proprietary solutions are reviewed in this paper as fundamental to derive the QoE influence factors that emerge as a result of adaptation. The main contribution is a comprehensive survey of QoE related works from human computer interaction and networking domains, which are structured according to the QoE impact of video adaptation. To be more precise, subjective studies that cover QoE aspects of adaptation dimensions and strategies are revisited. As a result, QoE influence factors of HAS and corresponding QoE models are identified, but also open issues and conflicting results are discussed. Furthermore, technical influence factors, which are often ignored in the context of HAS, affect perceptual QoE influence factors and are consequently analyzed. This survey gives the reader an overview of the current state of the art and recent developments. At the same time, it targets networking researchers who develop new solutions for HTTP video streaming or assess video streaming from a user centric point of view. Therefore, this paper is a major step toward truly improving HAS.

Comparative Study of Indexing Techniques for Data Dissemination in Wireless Environment

In the past few years there has been a rapid growth of mobile devices in the commercial market due to the emphasis of wireless data applications along with various evolving technologies. Data broadcast is the powerful tool for data dissemination such that it allows several users on the same channel by providing high bandwidth utilization consequently reducing the tuning time. This can be achieved if the data is indexed in the database such that the most frequently accessed data is kept together to reduce the search time in the database which in turn reduces the access time and improves the power consumption of the mobile users. This paper provides the analysis of various indexing techniques along with their advantages and disadvantages.

Multi-OLT and multi-wavelength PON-based open access network for improving the throughput and quality of services

Passive optical network (PON) provides enough bandwidth for combining multiple service providers׳ in addition to the fiber to the home (FTTH) network. Multiple optical line terminals (multi-OLT) PON-based hybrid network is an efficient access network that provides an effective solution for reducing the computational complexity of data packet processing of multiple service providers having different packet lengths and data rates. However, in the multi-OLT PON-based hybrid networks, data transmission in the single upstream channel requires a complicated dynamic bandwidth allocation (DBA) algorithm for improving the bandwidth sharing efficiency among the multiple service providers. In this paper, we propose a new network architecture for a PON-based open access network (OAN) where every optical network unit (ONU) of the PON will be shared by all the service providers and in the central office multiple OLTs will be connected to handle the data packets of multiple service providers. In the upstream direction, we propose to use multiple wavelengths for modulating the data packets of multiple service providers and to avoid the requirement of a complicated DBA algorithm. The simulation results show that the multi-OLT and multi-wavelength PON-based OAN (MM-OAN) provides higher bandwidth utilization, higher upstream efficiency and higher throughput with a lower overhead to data ratio and jitter than the single-OLT and single wavelength PON-based OAN (SS-OAN). The overall throughput of the proposed scheme has been increased more than by a factor equal to the number of wavelengths employed than that of the SS-OAN.

Performance analysis and improvement of loss recovery mechanisms in star OBS networks

In OBS networks, burst loss affects negatively the performance of the higher layers. Proactive loss recovery mechanisms, such as burst cloning, have the advantage of low burst delay but it suffers from low bandwidth utilization. However, reactive loss recovery mechanisms, such as burst retransmission, have the advantage of high bandwidth utilization but at the cost of high burst delay. In this paper, we present an analysis of this trade-off and we propose two new schemes to improve bandwidth utilization while keeping burst delay as low as possible in star OBS networks. The first scheme controls the retransmissions. The second scheme combines burst cloning and burst retransmission mechanisms. Analytical and simulation results show that the both schemes achieve high bandwidth utilization. The results confirm also that compared to basic burst retransmission scheme, the first scheme reduces burst delay only at moderate and high load, however, the second scheme reduce delay at every load.

The design of bidirectional RoF system based on optical coherent technology and improved OFDM mechanism

In this paper, we propose a bidirectional radio over fiber system based on the improved orthogonal frequency division multiplexing (OFDM) format and optical heterodyne. With OFDM and coherent receiving technology, the system achieves high bandwidth utility efficiency and excellent transporting property. Using optical heterodyne, the system implements the 60 GHz wireless access without adding radio source. We evaluate the performance of system in terms of bit error rate, coverage area, receiving constellation through Monte-Carlo simulation method and obtain the system as excellent access property.

Green multicast grooming based on cross-shared protection in optical WDM networks

Currently, multicast survivability in optical network obtains more attention. This paper focuses on the field of multicast grooming shared protection in green optical network and designs a novel auxiliary graph and a shared matrix to address the survivable multicast resource consumption. This paper also proposes a new heuristic called Green Multicast Grooming algorithm based on spanning path Cross-Shared protection (GMG-CSP), in which network reliability, energy efficiency and resource utilization are jointly considered. Simulation results testify that, compared to other algorithms, the proposed GMG-CSP not only has lower blocking probability and higher bandwidth utilization ratio, but also saves more energy.

Adaptive-Acceleration Data Center TCP

Providing deadline-sensitive services is a challenge in data centers. Because of the conservativeness in additive increase congestion avoidance, current transmission control protocols are inefficient in utilizing the super high bandwidth of data centers. This may cause many deadline-sensitive flows to miss their deadlines before achieving their available bandwidths. We propose an Adaptive-Acceleration Data Center TCP, A $\!^2$ DTCP, which takes into account both network congestion and latency requirement of application service. By using congestion avoidance with an adaptive increase rate that varies between additive and multiplicative, A $\!^2$ DTCP accelerates bandwidth detection thus achieving high bandwidth utilization efficiency. At-scale simulations and real testbed implementations show that A $\!^2$ DTCP significantly reduces the missed deadline ratio compared to D $\!^2$ TCP and DCTCP. In addition, A $\!^2$ DTCP can co-exist with conventional TCP as well without requiring more changes in switch hardware than D $\!^2$ TCP and DCTCP.

A Dynamic Bandwidth Allocation Algorithm with QoS Support in Multilink Access Network

Aiming at the problem of high packets delay and low bandwidth utilization ratio of bandwidth allocation algorithm with QoS in multilink access network environment, the structure of bandwidth allocation with QoS support is analyzed, an algorithm that using residual bandwidth reallocation dynamically for different QoS request is designed. We compared our proposed algorithm to other existing DBAQoS algorithms through extensive simulations, the simulation experiments show that the algorithm can reduce the data transmission delay and improve the bandwidth utilization ratio effectively.

A beacon-based handover scanning mechanism with QoS support in WiMAX femtocell architecture

WiMAX femtocell architecture has gained a lot of attention because of its better indoor service provision through traffic sharing between WiMAX and femtocell. However, since the signal of a WiMAX base station (BS) is usually stronger than that of a femtocell base station (fBS), the handover procedure of mobile stations may not be triggered due to the stronger signal association. And, a huge number of fBSs deployed within a WiMAX BS coverage area will require extra power to scan all fBSs for a handover determination. In this article, we propose a beacon-based handover scanning mechanism with Quality of Service (QoS) support. Through the modified beacons and MOB_NBR-ADV messages, a neighbor cell list with QoS parameters is generated automatically at each mobile station. The decision criteria for handover triggering and an appropriate target cell selection are also presented. The QualNet simulation results demonstrate that along with increased fBSs, the proposed mechanism can improve the total system throughput from 37% to 51% and obtain higher bandwidth utilization in the case of increasing number of fBSs, as compared with Full Scan and Neighbor Cell Information Mechanisms.

Self-Stabilizing TDMA Algorithms for Dynamic Wireless Ad Hoc Networks

In dynamic wireless ad hoc networks (DynWANs), autonomous computing devices set up a network for the communication needs of the moment. These networks require the implementation of a medium access control (MAC) layer. We consider MAC protocols for DynWANs that need to be autonomous and robust as well as have high bandwidth utilization, high predictability degree of bandwidth allocation, and low communication delay in the presence of frequent topological changes to the communication network. Recent studies have shown that existing implementations cannot guarantee the necessary satisfaction of these timing requirements. We propose a self-stabilizing MAC algorithm for DynWANs that guarantees a short convergence period, and by that, it can facilitate the satisfaction of severe timing requirements, such as the above. Besides the contribution in the algorithmic front of research, we expect that our proposal can enable quicker adoption by practitioners and faster deployment of DynWANs that are subject changes in the network topology.

Radio resource allocation algorithms for multi-service OFDMA networks: the uniform power loading scenario

Adaptive Radio Resource Allocation is essential for guaranteeing high bandwidth and power utilization as well as satisfying heterogeneous Quality-of-Service requests regarding next generation broadband multicarrier wireless access networks like LTE and Mobile WiMAX. A downlink OFDMA single-cell scenario is considered where heterogeneous Constant-Bit-Rate and Best-Effort QoS profiles coexist and the power is uniformly spread over the system bandwidth utilizing a Uniform Power Loading (UPL) scenario. We express this particular QoS provision scenario in mathematical terms, as a variation of the well-known generalized assignment problem answered in the combinatorial optimization field. Based on this concept, we propose two heuristic search algorithms for dynamically allocating subchannels to the competing QoS classes and users which are executed under polynomially-bounded cost. We also propose an Integer Linear Programming model for optimally solving and acquiring a performance upper bound for the same problem at reasonable yet high execution times. Through extensive simulation results we show that the proposed algorithms exhibit high close-to-optimal performance, thus comprising attractive candidates for implementation in modern OFDMA-based systems.

Dynamic Bandwidth Allocation Algorithm With Proper Guard Time Management Over Multi-OLT PON-Based Hybrid FTTH and Wireless Sensor Networks

A passive optical network (PON) is a highly capable access network that effectively converges several service providers, without suffering from any bandwidth deficiency. However, a PON consisting of a single optical line terminal (OLT) for multiple service providers increases the computational complexity for data packet processing in the OLT, resulting in a longer time delay and more packet loss. A multi-OLT PON-based access network is an effective solution for reducing the computational complexity of data packet processing in a hybrid network of multiple service providers. The most important issue concerning the multi-OLT PON is the sharing efficiency of upstream channels among multiple service providers having different packet lengths and data rates. In this paper, we propose a dynamic bandwidth allocation algorithm called adaptive limited dynamic bandwidth allocation for multi-OLT PON (ALDBAM). The proposed scheme is a modified version of adaptive limited dynamic bandwidth allocation (ALDBA) algorithms that we proposed before, where both the ALDBA1 and ALDBA2 schemes are combined with proper guard time management and a modified multipoint control protocol. The simulation results show that the ALDBAM scheme provides lower packet delay with higher bandwidth utilization, higher upstream efficiency, and higher throughput than the conventional ALDBA1 and ALDBA2 schemes.

A New P2P Streaming Media VOD System Based on Window

Currently some P2P video-on-demand patterns using the corresponding technique to adjust and monitor network peer state, effectively reduce the multilayer peer forwarding delay, so as to ensure that the system has good stability and expansibility, but in response to the sudden resource request can not guarantee that the system load balancing. This paper presents a new P2P streaming media VOD system based on window, using a resource reservation mechanism for load balancing algorithm which can realize video server in each media stream between the rational allocation, give full play to the peer load capacity. The simulation shows that the system is able to respond to sudden resource request, and has high bandwidth utilization, effectively improves the performance of the system.

Relativity‐based access strategy for frequency hopping system

In this study, two relativity-based access strategies are proposed for frequency hopping system with cognitive ability (C-FH). Sensing module is added in the receiver to perform real-time measurement of channel states. The first access strategy is studied in consideration of partial relative FH pattern. The spectrum band is divided into several groups and each C-FH user can only jump over the channel group authorised by the active user. In the second access strategy, the C-FH user will adaptively choose an active user as the scheduler to apply for access. The application users may be rejected because of lack of resources or accepted to access the available channels in order of arranged sequence. The chosen scheduler will accept applications according to number of available channels and the spectrum resource will be shared in condition of being temporally correlated. With relativity-based strategies, FH patterns of users have the minimum Hamming correlation, even to zero. Markov chains are built to model the access processes. The performance analysis and the simulation results show that the relativity-based access strategy brings lower collision probability, higher bandwidth utilisation and higher normalised average throughput.