Priority‐based adaptive access barring for M2M communications in LTE networks using learning automata

Supporting a huge number of machine‐to‐machine devices with different priorities in Long Term Evolution networks is addressed in this paper. We propose a learning automaton (LA)–based scheme for dynamically allocating random access resources to different classes of machine‐to‐machine devices according to their priorities and their demands in each cycle. We then use another LA‐based scheme to adjust the barring factor for each class to control the possible overload. We show that by appropriate updating procedure for these LAs, the system performance asymptotically converges to the optimal performance in which the evolved node B knows the number of access‐attempting devices from each class a priori. Simulation results are provided to show the performance of the proposed scheme in random access resource allocation to defined classes and adjusting the barring factor for each of them.     

Comparison of coded orthogonal frequency division multiplexing and multicarrier code division multiple access systems for power line communications

Orthogonal frequency division multiplexing (OFDM) and multicarrier code division multiple access (MC‐CDMA) systems are comparatively evaluated for power line communications (PLC) in a frequency‐selective fading environment with additive coloured Gaussian noise which is used to model the actual in‐home power line channel. OFDM serves as a benchmark in order to measure the performance of various MC‐CDMA systems, since multicarrier modulation systems are considered the best candidate for this kind of channel. Both single‐user and multi‐user cases are taken into account, making use of the appropriate combiner schemes to take full advantage of each case. System efficiency is enhanced by the application of different coding techniques, a fact which shows that powerful coding can make the difference under such a hostile medium. The impact of block interleaving is investigated, while the simulation examines how different modulation schemes fair under the imposed channel conditions as well. The performance of the system is assessed by the commonly used bit error rate vs signal‐to‐noise ratio diagrams and there is also a comparison regarding throughput efficiency among all the tested systems. As stated in Section 4, a promising PLC application is attained. Copyright © 2004 John Wiley & Sons, Ltd.     

A new family of 2D variable-weight optical orthogonal codes for OCDMA systems supporting multiple QoS and analysis of its performance

A new family of two-dimensional variable-weight and constant-length optical orthogonal codes (2D VWOOCs) is proposed, and the code cardinality and BER performance for the corresponding OCDMA system are analyzed in this article. It is shown that the cardinality of 2D VWOOC is larger than that of constant-weight 2D OOC and close to the upper bound in theory. In an OCDMA network, the users employing 2D VWOOC codewords with larger Hamming weight outperform the users using 2D VWOOC codewords with smaller Hamming weight in bit-error-rate performance. Therefore, the OCDMA network employing 2D VWOOC can support diverse quality-of-services (QoS) classes and multimedia services, and make the better use of bandwidth resources in optical networks.

Service based CAC with QoS guarantee in mobile wireless cellular networks

The increasing variety and complexity of traffic in today's mobile wireless networks means that there are more restrictions placed on a network in order to guarantee the individual requirements of the different traffic types and users. Call admission control (CAC) plays a vital role in achieving this. In this paper, we propose a CAC scheme for multiple service systems where the predicted call usage of each service is used to make the admission decision. Our scheme enables real‐time traffic to be transmitted using shared bandwidth without quality of service (QoS) requirements being exceeded. This ensures that the utilization of the available wireless bandwidth is maximized. Information about the channel usage of each service is used to estimate the capacity of the cell in terms of the number of users that can achieve a certain bit error rate (BER). Priorities assigned to each service are used to allocate the network capacity. An expression for the handoff dropping probability is derived, and the maximum acceptance rate for each service that results in the estimated dropping probability not exceeding its QoS requirements is calculated. Each call is then accepted with equal probability throughout the duration of a control period. Achieved QoS during the previous control period is used to update the new call acceptance rates thus ensuring the dropping probability remains below the specified threshold. Simulations conducted in a wideband CDMA environment with conversational, streaming, interactive and background sources show that the proposed CAC can successfully meet the hard restraint on the dropping probability and guarantee the required BER for multiple services. Copyright © 2005 John Wiley & Sons, Ltd.     

Opportunistic delay‐margin‐based resource allocation for next‐generation wireless networks

This paper studies and develops efficient traffic management techniques for downlink transmission at the base station (BS) of multi‐service IP‐based networks by combining quality‐of‐service (QoS) provision and opportunistic wireless resource allocation. A delay‐margin‐based scheduling (DMS) for downlink traffic flows based on the delays that each packet has experienced up to the BS is proposed. The instantaneous delay margin, represented by the difference between the required and instantaneous delays, quantifies how urgent the packet is, and thus it can determine the queuing priority that should be given to the packet. The proposed DMS is further integrated with the opportunistic scheduling (OPS) to develop various queueing architectures to increase the wireless channel bandwidth efficiency. Different proposed integration approaches are investigated and compared in terms of delay outage probability and wireless channel bandwidth efficiency by simulation. Copyright © 2010 John Wiley & Sons, Ltd.     

光无线混合宽带接入网QoS感知DBA算法

针对光无线混合宽带接入网的特点,提出一种考虑公平性的Qo S感知DBA算法(QDBA)。仿真结果表明:与已有算法相比,QDBA具有较高的吞吐量和较低的平均时延,同时具有更好的公平性和Qo S保障。     

Multiple access interference and multipath interference analysis of orthogonal complementary code‐based ultra‐wideband systems over multipath channels

In order to alleviate multiple access interference and multipath interference of ultra‐wideband (UWB) system, we propose the orthogonal complementary code (OCC)‐based direct‐sequence UWB system and offset‐stacking (OS)‐UWB system. OCC has perfect partial autocorrelation and cross‐correlation characteristics. With the application of OCC in UWB system, we can obtain better performance in multiple access interference and multipath interference. The proposed OS‐UWB structure can also achieve variable data rate transmission because of its innovative OS spreading technique. Theoretical analysis and simulation results show that the proposed UWB system can achieve excellent performance and outperform the unitary code‐based direct‐sequence UWB system. Copyright © 2013 John Wiley & Sons, Ltd.     

Construction and performance analysis of 2-D variable-length variable-weight optical orthogonal codes

In this paper, a new generation algorithm of a two-dimensional variable-length and variable-weight optical orthogonal codes (2-D VLVWOOCs) is proposed. By analysis of the BER performance for the corresponding optical code division multiple access (OCDMA) system, it is shown that the users with different codewords have significant differences in performance. Users with heavier-weight address matrices always outperform those with lighter-weight address matrices, and shorter-length and longer-length matrices support high bit-rate and low bit-rate in OCDMA applications, respectively. Therefore, heavier-weight shorter-length matrices can accommodate high bit-rate and high-quality of services (QoS) (e.g., real-time video), and lighter-weight longer-length matrices can achieve low bit-rate and low-QoS (e.g., voice). The system performance becomes worse as the users concentrate on one type of service. Especially, a surge of the number of users with shorter-length matrices has particularly impact on system performance. Thus, the 2-D VLVWOOCs can be used to provide many different types of services with different rate-levels and different levels of QoS, and simultaneously make better use of bandwidth resources in optical networks.

QoS routing through alternate paths in wireless ad hoc networks

Quality of service (QoS) routing plays an important role in QoS provisioning for mobile ad hoc networks. This work studies the issue of route selection subject to QoS constraint(s). Our method searches for alternate routes with satisfied QoS requirement(s) to accommodate each communication request when the shortest path connecting the source–destination pair of the request is not qualified. In order to effectively reduce protocol overhead, a directed search mechanism is designed to limit the breadth of the searching scope, which aims at achieving a graceful tradeoff between the success probability in QoS route acquisition and communication overhead. Efficient hop‐by‐hop routing protocols are designed for route selection subject to delay and bandwidth constraint, respectively. Simulation results show that the designed protocols can achieve high performance in acquiring QoS paths and in efficient resource utilization with low control overhead. Copyright © 2004 John Wiley & Sons, Ltd.     

机器类设备基于不同时延需求分组的随机接入方法

针对大规模机器类通信中拥塞导致的时延敏感设备时延高和接入成功率低的问题,提出将小区中设备按时延要求分组,对不同组设备引入不同的退避模型,分析时延敏感设备的时延和吞吐量,按照不同组中设备的时延需求动态分配前导数目,同时通过调整接入类限制因子实现吞吐量的优化。仿真结果表明,在给定时延敏感设备的时延限制条件时,与统一退避的机制对比,所提分组机制的时延敏感设备能够满足时延要求,并且提高了接入效率。     

Telesurgery QoS improvement over SDN based on a Type‐2 fuzzy system and enhanced cuckoo optimization algorithm

Telemedicine is a new area based on the information and communication technology for collecting, storing, organizing, retrieving and exchanging medical information. One of the most important applications of telemedicine is indeed telesurgery in which an efficient telecommunication infrastructure between the surgery room and remote surgeons need to be established. One of the most important issues to be tackled in telesurgery is to find favorable links for routing as well as providing high Quality of Service (QoS). In this paper, an efficient model based on the hybridization of Type‐2 Fuzzy System (T2FS) and Cuckoo Optimization Algorithm (COA) over the Software Defined Networks (SDN) is proposed in order to achieve optimal and reliable routes for telesurgery application. Using T2FS, the fitness of the links is determined; then, a COA is conducted over the Constraint Shortest Path (CSP) problem to find the best routes. Delay is considered as a CSP problem which is satisfied by trying to find the paths with minimum cost. Due to the NP‐completeness of the CSP problem, an Enhanced COA (so‐called E‐COA) is proposed and utilized as a metaheuristic solver. To the best of our knowledge, this paper is the first SDN‐based communication model that applies both T2FS and E‐COA for assigning proper costs to the network's links, and solves the consequence CSP problem according to the QoS requirement for telesurgery. The model also recognizes and preserves the second‐best routes in order to keep the reliability for such a critical application. In addition to the simulations, the performance evaluation is also conducted on a real experimental scenario. Many comparisons are carried out between the proposed model and other conventional methods, and the evaluation study shows the superiority of the proposed model on all the three QoS‐related metrics, i.e. average end‐to‐end delay, packet loss ratio and PSNR.     

Improving node behaviour in a QoS control environment by means of load‐dependent resource redistributions in LANs

An important means to guarantee an acceptable quality of service in networks with real‐time communication requirements is the reservation of resources at connection setup time. However, such reserved resources, e.g. transmission bandwidth, may be unused as a consequence of the variations in the actual resource demands. Therefore, a more efficient resource utilization is possible if communicating stations or end‐users dynamically hand over some of the free resources temporarily to the other communication partners, e.g. of a ‘broadcast network’. This paper concentrates on two fundamental problems of such a demand‐based sharing of resources: on the one hand, estimation of the current resource requirement on the basis of load measurements is investigated and, on the other hand, we elaborate efficient algorithms for resource sharing respecting real‐time requirements. The algorithms proposed for load estimation and for resource sharing are evaluated analytically with respect to their efficiency for worst‐case, average‐case and realistic load scenarios. Our approach suggested for resource and traffic management allows one to achieve significantly better utilization of network resources. Copyright © 2005 John Wiley & Sons, Ltd.     

主动队列管理机制在无线系统中的优化

主动队列管理(AQM)是对抗拥塞的重要手段,其经典算法之一是随机早期丢弃,简称RED。为使其能适应无线传输高突发误帧的特点,本文提出了一种基于平均队列长度和平均包到达速率的改进RED算法,分析了其相对于传统RED算法在预防和处理拥塞时的优势。同时针对无线信道的时变特性,提出自适应MIR速率调整,以提高频谱利用率和进一步降低拥塞概率,并讨论了其对于系统性能的改善。     

The revisit of QoS routing based on non‐linear Lagrange relaxation

The development of efficient quality of service (QoS) routing algorithms in a high‐speed networking or the next generation IP networking environment is a very important and at the same time very difficult task due to the need to provide divergent services with multiple QoS requirements. Recently, a heuristic algorithm H_MCOP, which is based on a non‐linear Lagrange relaxation (NLR) technique, has been proposed to resolve the contradiction between the time complexity and the quality of solution. Even though H_MCOP has demonstrated outstanding capability of finding feasible solutions to the multi‐path constrained (MCP) problem, it has not exploited the full capability that an NLR‐based technique could offer. In this paper, we propose a new NLR‐based heuristic called NLR_MCP, in which the search process is interpreted from a probability's perspective. Simulation results indicate that NLR_MCP can achieve a higher probability of finding feasible solutions than H_MCOP. We also verify that the performance improvement of a MCP heuristic has a tremendous impact on the performance of a higher level heuristic that uses a MCP heuristic as the basic step. Copyright © 2006 John Wiley & Sons, Ltd.     

E-OBS网络中一种基于窗口的资源预留机制

为了有效地降低突发包的阻塞率和保证网络的服务质量,提出了模拟光突发交换（E-OBS）网络中一种偏置时间连续可变的基于窗口资源预留机制。在E-OBS核心路由器的控制信道（CC）上设置资源预留窗口,以此决定是否允许控制包为相应的突发包预留链路资源,并且给出了该机制下关于阻塞概率的近似方程式。仿真结果表明,适当增加资源预留窗...     

Space‐time diversity‐enhanced QoS provisioning for real‐time service over MC‐DS‐CDMA based wireless networks

In order to support the quality‐of‐service (QoS) requirements for real‐time traffic over broadband wireless networks, advanced techniques such as space‐time diversity (STD) and multicarrier direct‐sequence code division multiple access (MC‐DS‐CDMA) are implemented at the physical layer. However, the employment of such techniques evidently affects the QoS provisioning algorithms at the medium access control (MAC) layer. In this paper, we propose a space‐time infrastructure and develop a set of cross‐layer real‐time QoS‐provisioning algorithms for admission control, scheduling, and subchannel‐allocations. We analytically map the parameters characterizing the STD onto the admission‐control region guaranteeing the real‐time QoS. Our analytical analyses show that the proposed algorithms can effectively support real‐time QoS provisioning. Also presented are numerical solutions and simulation results showing that the STD can significantly improve the QoS provisioning for real‐time services over wireless networks. Copyright © 2007 John Wiley & Sons, Ltd.     

A study on a receiver‐based management scheme of access link resources for QoS‐controllable TCP connections

Although the bandwidth of access networks is rapidly increasing with the latest techniques such as DSL and FTTH, the access link bandwidth remains a bottleneck, especially when users activate multiple network applications simultaneously. Furthermore, since the throughput of a standard TCP connection is dependent on various network parameters, including round‐trip time and packet loss ratio, the access link bandwidth is not shared among the network applications according to the user's demands. In this thesis, we present a new management scheme of access link resources for effective utilization of the access link bandwidth and control of the TCP connection's throughput. Our proposed scheme adjusts the total amount of the receive socket buffer assigned to TCP connections to avoid congestion at the access network, and assigns it to each TCP connection according to characteristics in consideration of QoS. The control objectives of our scheme are (1) to protect short‐lived TCP connections from the bandwidth occupation by long‐lived TCP connections, and (2) to differentiate the throughput of the long‐lived TCP connections according to the upper‐layer application's demands. One of the results obtained from the simulation experiments is that our proposed scheme can reduce the delay of short‐lived document transfer perceived by the receiver host by up to about 90%, while a high utilization of access link bandwidth is maintained. Copyright © 2006 John Wiley & Sons, Ltd.     

An optimal solution to resource allocation among soft QoS traffic in wireless network

Optimization theory and nonlinear programming method have successfully been applied into wire‐lined networks (e.g., the Internet) in developing efficient resource allocation and congestion control schemes. The resource (e.g., bandwidth) allocation in a communication network has been modeled into an optimization problem: the objective is to maximize the source aggregate utility subject to the network resource constraint. However, for wireless networks, how to allocate the resource among the soft quality of service (QoS) traffic remains an important design challenge. Mathematically, the most difficult comes from the non‐concave utility function of soft QoS traffic in the network utility maximization (NUM) problem. Previous result on this problem has only been able to find its sub‐optimal solution. Facing this challenge, this paper establishes some key theorems to find the optimal solution and then present a complete algorithm called utility‐based allocation for soft QoS to obtain the desired optimal solution. The proposed theorems and algorithm act as designing guidelines for resource allocation of soft QoS traffic in a wireless network, which take into account the total available resource of network, the users’ traffic characteristics, and the users’ channel qualities. By numerical examples, we illustrate the explicit solution procedures.Copyright © 2013 John Wiley & Sons, Ltd.     

A survey of QoS enhancements for IEEE 802.11 wireless LAN

Quality‐of‐service (QoS) is a key problem of today's IP networks. Many frameworks (IntServ, DiffServ, MPLS etc.) have been proposed to provide service differentiation in the Internet. At the same time, the Internet is becoming more and more heterogeneous due to the recent explosion of wireless networks. In wireless environments, bandwidth is scarce and channel conditions are time‐varying and sometimes highly lossy. Many previous research works show that what works well in a wired network cannot be directly applied in the wireless environment. Although IEEE 802.11 wireless LAN (WLAN) is the most widely used IEEE 802.11 wireless LAN (WLAN) standard today, it cannot provide QoS support for the increasing number of multimedia applications. Thus, a large number of 802.11 QoS enhancement schemes have been proposed, each one focusing on a particular mode. This paper summarizes all these schemes and presents a survey of current research activities. First, we analyze the QoS limitations of IEEE 802.11 wireless MAC layers. Then, different QoS enhancement techniques proposed for 802.11 WLAN are described and classified along with their advantages/drawbacks. Finally, the upcoming IEEE 802.11e QoS enhancement standard is introduced and studied in detail. Copyright © 2004 John Wiley & Sons, Ltd.     

Throughput enhancement of cognitive M2M networks based on NOMA for 5G communication systems

One of the promising technologies for 5G cellular networks is machine‐to‐machine (M2M) communications. We propose a cognitive radio network (CR) that includes a primary cellular system and a secondary cognitive system. The primary cellular system has a primary client (PC) and the secondary cognitive system has M2M clients which are called secondary clients (SCs). In a conventional system of CR network based on orthogonal frequency division multiple access (CR‐OFDMA), when the primary client (PC) is absent, only one SC can obtain the idle spectrum. But, the SC must leave the spectrum when detecting the existence of the PC. So, the spectrum usage of this system is very low. This paper proposes a cooperative CR network based on nonorthogonal multiple access (CCR‐NOMA) for spectrum sensing using energy detection (ED) to allow multiple SCs to share the same frequency at the same time, but are differentiated according to the power domain or code domain, to improve spectrum efficiency of 5G communications and the transmission performance of CR network at the absence and presence of the PC. To evaluate the channel sensing performance of the ED technique in CCR‐NOMA, we derived a closed‐form expression between the achievable throughput and sensing time for the CCR‐NOMA system. The same analysis for the case of CR‐OFDMA is reproduced for the sake of comparison. The analysis showed that the CR‐NOMA system for M2M communication outperforms the CR‐OFDMA system for M2M communication for the same noncooperative and cooperative spectrum sensing and physical layer parameters.