Unicast Services Research Articles

Online AL-FEC policy problem on mobile unicast services

Forward error correction (FEC) is a method for error control of data transmission adopted in several mobile multicast standards. FEC is a feedback free error recovery method where the sender introduces redundant data in advance with the source data enabling the recipient to recover from different arbitrary packet losses. Recently, the adoption of FEC error control method has been boosted by the introduction of powerful Application Layer FEC (AL-FEC) codes, e.g. RaptorQ codes. Furthermore, several works have emerged aiming to address the shortcomings of AL-FEC protection application utilizing deterministic or randomized online algorithms to enhance the efficiency of AL-FEC error control method. In this work, since the investigation of AL-FEC application as primary or auxiliary error protection method over mobile multicast environments is a well investigated field but the opportunity of utilizing the AL-FEC over mobile unicast services as the only method for error control replacing common feedback based methods that are now considered to be obsolete, we provide an analysis on the feasibility of AL-FEC protection over unicast delivery utilizing online algorithms in conjunction with AL-FEC codes with exceptional recovery performance.

Hybrid services efficient provisioning over the network coding–enabled elastic optical networks

As a variety of services have emerged, hybrid services have become more common in real optical networks. Although the elastic spectrum resource optimizations over the elastic optical networks (EONs) have been widely investigated, little research has been carried out on the hybrid services of the routing and spectrum allocation (RSA), especially over the network coding–enabled EON. We investigated the RSA for the unicast service and network coding–based multicast service over the network coding–enabled EON with the constraints of time delay and transmission distance. To address this issue, a mathematical model was built to minimize the total spectrum consumption for the hybrid services over the network coding–enabled EON under the constraints of time delay and transmission distance. The model guarantees different routing constraints for different types of services. The immediate nodes over the network coding–enabled EON are assumed to be capable of encoding the flows for different kinds of information. We proposed an efficient heuristic algorithm of the network coding–based adaptive routing and layered graph-based spectrum allocation algorithm (NCAR-LGSA). From the simulation results, NCAR-LGSA shows highly efficient performances in terms of the spectrum resources utilization under different network scenarios compared with the benchmark algorithms.

Seamless Mobile Multimedia Broadcasting Using Adaptive Error Recovery

Multimedia services over mobile networks present several challenges, such as ensuring a reliable delivery of multimedia content, avoiding undesired service disruptions, or reducing service latency. HTTP adaptive streaming addresses these problems for multimedia unicast services, but it is not efficient from the point of view of radio resource consumption. In Long-Term Evolution (LTE) networks, multimedia broadcast services are provided over a common radio channel using a combination of forward error correction and unicast error recovery techniques at the application level. This paper discusses how to avoid service disruptions and reduce service latency for LTE multimedia broadcast services by adding dynamic adaptation capabilities to the unicast error recovery process. The proposed solution provides a seamless mobile multimedia broadcasting without compromising the quality of the service perceived by the users.

Restoration methods for cloud multicast virtual networks

Providing reliability guarantees for services hosted in cloud data center networks is a well studied problem that received much attention from the literature in recent years. Yet, the existing literature failed to account for the mode of communication that these hosted services may exhibit. Rather, it is assumed that the constituent Virtual Machines (VMs) are always exchanging traffic in a one-to-one communication mode. This paper is concerned with the problem of restoring failed services with a one-to-many communication mode, the mode of communication for a multitude of multicast applications and services hosted today in the cloud. Through motivational examples we show that the problem of restoring multicast Virtual Networks (VNs) greatly differs from that of unicast services, thereby demanding separate attention. To this extent, we formally define the problem of restoring multicast services in event of facility node failure, and we mathematically formulate it using an Integer Linear Programming (ILP) model. Further, we propose REAL: a multicast virtual network re storation al gorithm. REAL distinguishes the failure of multicast source node from that of multicast terminal nodes, and adopts a hop-to-hop search to handle receiver or terminal node failures, and a path convergence approach to recover from source node failures. We evaluate our proposed schemes against a Greedy and a Steiner-based restoration schemes, and we show that our suggested method outperforms its peers in terms of restoration ratio and total achievable revenue.

On control plane algorithms for Carrier Ethernet networks: Unicast, multicast provisioning and control traffic reduction

Carrier Ethernet systems are actively replacing SONET/SDH networks for transport of provider data. After much standardization in both the IEEE and the IETF, Carrier Ethernet has evolved as a rich carrier-class technology. The standards do not focus on specific implementation aspects of providing guaranteed service-oriented features that are intrinsic towards successful replacement of SONET/SDH by Carrier Ethernet solutions. In this paper, we consider the engineering aspects of the Carrier Ethernet software defined control plane for provisioning, managing and maintaining services. Specifically, we propose methods for provisioning guaranteed unicast services considering the underlying network state. The problem is difficult due to the complex nature of admission control coalesced with subjective user requirement that is not easy to rationalize across a network. We also investigate the problem of sub-50ms protection of multicast connections and propose a unique, tractable algorithm within the control plane for enabling carrier-class multicast services. Finally, we focus on overall control traffic reduction schemes. An intuitive merging algorithm is proposed that minimizes control traffic in Carrier Ethernet domains. A simulations study extensively evaluates the proposed techniques.

Optimal Polynomial Time Algorithm for Restoring Multicast Cloud Services

The failure-prone nature of data center networks has evoked countless contributions to develop proactive and reactive countermeasures. Yet, most of these techniques were developed with unicast services in mind. When in fact, multiple services hosted in data center networks today rely on multicast communication to disseminate traffic. Hence, the existing survivability schemes fail to cater to the distinctive properties and quality of service requirements that multicast services entail. This letter is devoted to understanding the ramifications of facility node or substrate link failure on multicast services residing in cloud networks. We formally define the multicast virtual network restoration problem and prove its NP-complete nature in arbitrary graphs. Furthermore, we prove that the problem can be solved in polynomial-time in multi-rooted treelike data center network topologies.

Instantly Decodable Network Coding for Multiple Unicast Retransmissions in Wireless Point-to-Multipoint Networks

Instantly decodable network coding (IDNC) reduces the completion delay of packet retransmission for multicast services in wireless point-to-multipoint (PMP) networks. Compared with multicast services, multiple unicast services may be more common in PMP networks. Reducing completion delay using IDNC for multiple unicast services is still an open problem. According to the construction features of IDNC, we find that if some unicast retransmissions are combined as a retransmission group, IDNC benefits from network coding (NC) considerably, which increases retransmission efficiency. Based on this observation, we study the total completion delay of all these unicast transmissions with intersession NC. In this paper, we provide an intersession insight into the IDNC method. Specifically, we propose a framework that contains 1) a general solution to this minimum completion delay (MCD) problem, which is modeled as a bin-packing problem, and 2) a lower bound of completion delay for the MCD solution. Additionally, we provide a high-efficiency greedy algorithm to solve the MCD problem with low computational complexity. Simulation results demonstrate that the proposed method saves almost 43% retransmissions in PMP networks and makes 87.5% retransmission packets benefit from the NC transmission.

Fast and low-complexity encoding of Raptor codes based on operation lists for known source block lengths

Raptor codes can provide good error correction capability and efficient encoding and decoding rate. Its fountain code property is effective in avoiding packet retransmission for both unicast and multicast service delivery. Hence, there are many mobile, vehicular and broadband applications adopting it such as mobile multimedia broadcasting, multimedia communications for high-speed rails and broadband IPTV systems. In this paper, we present an efficient systematic Raptor codes encoder based on operation lists for known source block lengths. For a Raptor codes application that can frequently use one or several fixed source block lengths (i.e., the number of source symbols in a source block), we could produce the corresponding operation lists in advance and use them to generate the encoding symbols more efficiently. We first introduce the basic architecture of the proposed Raptor encoder, and then describe the details about how to generate operation lists and Raptor intermediate symbols. The simulation results show that our encoder is at least two times faster than the conventional Raptor codes encoder which is adopted by 3GPP and DVB-H. Besides, the reduction on CPU utilization for a real Raptor-based streaming server is described, which is from 11.59 % to 53.41 %, depending on the employed source block length and symbol size.

Distributed Load Balancing for Multi-User Multi-Class Traffic in MIMO-LTE-A Networks

In LTE network, load imbalance is the crucial issue which needs to be handled in order to exploit most of the benefit from LTE without degrading the throughput. In this study, we have proposed a Distributed Load Balancing for Multi-user Multi-class Traffic in MIMO-LTE Networks. First, we have proposed a robust load balancing framework to efficiently handle the traffic and also to keep the throughput as high as possible. To detect the overloaded cell, Call Blocking Ratio (CBR) is used as triggering mechanism. To minimize the load, optimization solution is implemented for unicast service and multicast service by selecting the proper transmission mode between Single Frequency Network (SFN) and Point to Multipoint (PTM) network. Moreover, to efficiently balance the congested cell detected by CBR Heaviest-First-Load-Balancing algorithm is implemented to avoid congestion in the traffic.

Impact of Playout Buffering on Mobile TV Performance

We study in this work the quality of experience of live mobile TV users in the presence of a playout buffer at the receiver side. We specifically consider an LTE network delivering both unicast and broadcast services, and study two cases: i. lossless channels where interruptions in mobile TV delivery are due to the absence of resources at the base station because they are totally consumed by higher priority real-time voice services, and ii. lossy channels, where we propose to exploit the existence of feedback channels to request, if possible, retransmission of the lost video frame. We derive in both cases several QoS metrics pertaining to mobile TV performance, such as interruption frequency and duration as well as video frame loss probability. Our results show the trends of these metrics as a function of several system parameters and yield design rules for network planning as well as for the playout buffer so as to enhance efficiently the live TV watching experience.

Correction to “An Efficient Game Form for Unicast Service Provisioning” [Feb 12 392-404

This note corrects an error in the above paper (ibid., vol. 57, no. 2, pp. 392-404, Feb. 2012).

A General Mechanism Design Methodology for Social Utility Maximization with Linear Constraints

Social utility maximization refers to the process of allocating resources in a way that maximizes the sum of agents' utilities, under the system constraints. Such allocation arises in several problems in the general area of communications, including unicast (and multicast multi-rate) service on the Internet, as well as in applications with (local) public goods, such as power allocation in wireless networks, spectrum allocation, etc. Mechanisms that implement such allocations in Nash equilibrium have also been studied but either they do not possess the full implementation property, or are given in a case-by-case fashion, thus obscuring fundamental understanding of these problems. In this paper we propose a unified methodology for creating mechanisms that fully implement, in Nash equilibria, social utility maximizing functions arising in various contexts where the constraints are convex. Two additional design goals are the focus of this paper: a) the size of the message space scaling linearly with the number of agents (even if agents' types are entire valuation functions), b) allocation being feasible on and off equilibrium.

Survivable provisioning for multicast service oriented virtual network requests in cloud-based data centers

Network virtualization technology plays an important role in cloud-based data centers that serve as an effective method for provisioning a flexible and highly adaptable shared substrate network to satisfy the demands of various applications. Although there has been some work on efficient mapping of unicast service oriented virtual networks there has been very limited work on addressing the problem of efficient mapping of multicast oriented virtual networks. Furthermore, how to guarantee survivability of multicast service oriented virtual network request has not been studied.In this work, we investigate the survivable multicast service oriented virtual network mapping (SMVNM) problem and propose an efficient algorithm for solving this problem. We first formulate the SMVNM problem with the objective of minimizing mapping cost by using mixed integer linear programming. We then design an efficient algorithm to solve this problem since it is NP-hard. We validate and evaluate our framework and algorithms by conducting extensive simulations on different realistic networks under various scenarios, and by comparing with existing approaches. The simulation results show that our approach outperforms existing solutions.

Resources Allocation Scheme Based on Mode Switch for Multicast Services in MBSFN

The multimedia broadcast and multicast services (MBMS) in 3GPP LTE is characterized by multicast broadcast single frequency network (MBSFN) operation. The multicast services are transmitted by single frequency network (SFN) mode, and the unicast services are delivered with point-to-point (PTP) mode. To avoid the network congestion of the multicast services in MBSFN, a novel resources allocation scheme (RAS) based on mode switch for the multicast services is proposed. The RAS takes advantages of the mode switch between SFN and PTP for the multicast services and minimizes the demanded radio resources of the maximum load cell. The simulation results show that the proposed RAS needs less demanded radio resources of the maximum load cell than SFN mode for all the multicast services.

A Novel Authentication Scheme for V2I Communication Based on WAVE Unicast Services

One of the most challenging issues in vehicular network designs is security matter. Particularly, there have been several potential attacks (e.g., message alteration, eavesdropping, privacy violation, and replay) on Vehicle to Infrastructure (V2I) communication. Most previous studies have based on Public Key Infrastructure (PKI) and authentication in broadcast services. By relying on the PKI solutions, cryptographic overhead and the management difficulties of public key certificates can be problematic. Furthermore, broadcast services can cause network flooding. Hence, this paper proposes a novel authentication scheme based on WAVE unicast services to reduce the PKI overhead between vehicles and Road Side Units (RSU). The new scheme is based on Pairwise Transient Key (PTK) procedures with a few extra authentication steps. To evaluate the new scheme, we have experimented on a Network Simulator (NS-2) under both city and highway scenarios. The experimental results have demonstrated that our new scheme introduces only small WAVE Short Message (WSM) delay. The new scheme is also flexible to use in various scenarios under different road situations.

Radio Resource Allocation for Scalable Video Services Over Wireless Cellular Networks

Good quality video services always require higher bandwidth. Hence, to provide the video services e.g., multicast/broadcast services (MBSs) and unicast services along with the existing voice, internet, and other background traffic services over the wireless cellular networks, it is required to efficiently manage the wireless resources in order to reduce the overall forced call termination probability, to maximize the overall service quality, and to maximize the revenue. Fixed bandwidth allocation for the MBS sessions either reduces the quality of the MBS videos and bandwidth utilization or increases the overall forced call termination probability and of course the handover call dropping probability as well. Scalable video coding (SVC) technique allows the variable bit rate allocation for the video services. In this paper, we propose a bandwidth allocation scheme that efficiently allocates bandwidth among the MBS sessions and the non-MBS traffic calls (e.g., voice, unicast, internet, and other background traffic). The proposed scheme reduces the bandwidth allocation for the MBS sessions during the congested traffic condition only to accommodate more calls in the system. Instead of allocating fixed bandwidths for the MBS sessions and the non-MBS traffic, our scheme allocates variable bandwidths for them. However, the minimum quality of the videos is guaranteed by allocating minimum bandwidth for them. Using the mathematical and numerical analyses, we show that the proposed scheme maximizes the bandwidth utilization and significantly reduces the overall forced call termination probability as well as the handover call dropping probability.

P2-Cycles: p-Cycles with parasitic protection links

The p-cycle and its Failure Independent Path Protection (FIPP) extension are known to be efficient and agile protection strategies. The p-cycle is pre-configured such that if there is a failure, only the switches at two end nodes need to be reconfigured. In this paper, we extend the p-cycle by allowing cycles to have attached links, called Parasitic Protection Links (PPL), in order to protect paths whose source and destination nodes are not only located on the cycle but also connected by a PPL to the cycle. A p-cycle with PPL is named p2-cycle.We address the unicast service protection problem against single-link failures by using p2-cycle in mesh networks for both static and dynamic traffic scenarios. In the static case, the problem is formulated as an Integer Linear Program (ILP). We further propose two p2-cycle based heuristic algorithms, Strict Routing Protection (SRP) and Flexible Routing Protection (FRP), to address the dynamic traffic case. The numerical results show that the p2-cycle scheme provides better capacity efficiency than the FIPP p-cycle scheme in all the traffic scenarios considered and achieves only less than 1% extra total cost over the optimum in COST239, provided by Shared Backup Path Protection (SBPP) approach when the traffic load is high. We also study the failure recovery performance in terms of average number of switch reconfigurations (NOR), and show that the performance of the p2-cycle becomes much better than that of SBPP and gets close to FIPP as the traffic demand increases. In the dynamic case, both SRP and FRP outperform FIPP p-cycle schemes in terms of blocking probability in most scenarios considered. In general, the p2-cycle protection scheme outperforms the p-cycle based in terms of capacity efficiencies which being slightly slower in terms of traffic recovery speed.

A resource allocation algorithm for OFDM-based cellular system serving unicast and multicast services

In this article, we propose a resource allocation algorithm for orthogonal frequency division multiplexing-based cellular system that serves users each of which requests a regular service or a multimedia broadcast multicast service (MBMS). We assume that the MBMSs are considered for video services such as mobile TV. In order to efficiently serve the users with heterogeneous channel conditions, we employed channel-adaptive video streams by using scalable video coding (SVC), where a realistic multicast configuration is considered for multicasting the SVC streams. Therefore, we designed the cellular system to serve constant and flexible bit rates for the regular services and the MBMSs, respectively. Thus, we consider three objectives when allocating the bandwidth resources, where total transmit power is regulated. First, the bit rate of each regular service has to be guaranteed. Second, the minimum bit rate of each MBMS for achieving the minimum video quality has to be guaranteed. Third, the average video quality of the users requesting MBMSs has to be maximized. In order to achieve the objectives, we propose to quantify the service quality of each service, and then find the resource allocation that maximizes the total service quality. By using the computer simulation results, we could verify that the three objectives can efficiently be achieved. Also, we could verify that the performance of the proposed algorithm is superior to that of the previous algorithm designed to maximize the total bit rate while guaranteeing the minimum bit rates.

Integrated power‐saving scheduling algorithm in IEEE 802.16e networks

In IEEE 802.16e networks, with the popularisation of multimedia services, multicast and unicast services can coexist in one mobile subscriber station (MSS). The mobile devices are generally powered by battery, which is limited in energy. Thus, power saving is an important issue to be considered for extending the lifetime of the MSSs. The authors have proposed a multicast services-based scheduling (MSBS) algorithm that improves the energy efficiency of both unicast and multicast services, while satisfying the quality of service requirements of the MSSs in 802.16e wireless networks. MSBS schedules the packets in such a way that each packet is transmitted before its deadline and the energy consumed by the MSSs is reduced by minimising the number of state transitions by the MSSs. The simulation results show that MSBS can produce significant overall energy-saving and prolonged lifetime as compared to other scheduling schemes in 802.16e wireless networks.

Channel-aware adaptive resource allocation for multicast and unicast services in orthogonal frequency division multiplexing systems

To support the multicast and unicast services in the orthogonal frequency division multiplexing system simultaneously, a channel-aware adaptive resource allocation algorithm is proposed to maximise the total throughput of the unicast service while guaranteeing the required quality of service (QoS) for the multicast service. The two-step optimisation scheme is developed to solve the problem based on the perfect channel state information at the base station: first, subcarriers are allocated to the multicast and the unicast services under the assumption that power is divided equally to every subcarrier. Especially, the noisy chaotic neural network with a new parameter set is applied to allocate the subcarriers to the unicast service by elaborately constructing the energy function to fully exploit the multiuser diversity gain, the optimal solution is found successfully through its rich neurodynamics; Secondy, the power averagely allocated to the unicast service is reallocated quickly in a linear water-filling fashion. Compared with existing algorithms the proposed algorithm achieves higher spectrum efficiency and better bit-error rate for the multicast service, also higher throughput for the unicast service.