A partial-success-rate-based resource reservation scheme for slotted OBS networks

Optical burst switching (OBS) is a promising technology for next-generation optical networks. Slotted OBS is an improved version of OBS to reduce burst loss rate, in which wavelength channels are divided into time slots. Slotted OBS has an implicit and under-used property that resources for two bursts with the same source and the same destination are interchangeable. The property further means that resource for a long-distance burst can be partially used by a short-distance burst. In this paper, we utilize the property to design a resource reservation scheme for slotted OBS networks. The scheme reserves a batch of slots every time; the specific number of slots is calculated according to number of arrived bursts and partial success rate (a newly introduced conception in this paper) at each node. Simulation results show that the proposed scheme can get lower burst loss rate, comparing with the well-performing two-way signaling scheme.     

光突发交换网络的一种批量重调度算法

数据信道调度算法是光突发交换网络的关键算法.按需重调度算法(0DBR)只重调度一个突发,对性能提高有限,为此提出批量重调度算法.仿真结果表明该算法突发丢失率低于LAUC、LAUC-VF和按需重调度算法.     

Burst transmission algorithm to improve packet level performance in contention-free slotted OBS networks

In contention-free slotted optical burst switching (SOBS) networks, controllers are utilized in order to manage the time-slot assignment, avoiding congestions among multiple burst transmissions. In this network, bursts are never lost at intermediate nodes but packets are lost at an ingress edge node due to a burst transmission algorithm. In addition, packet transmission delay increases depending on the algorithm. In order to improve packet level performance, in this paper, we propose a new burst transmission algorithm. In this method, two different thresholds are used; one is used to send a control packet to a controller and the other is used to assemble a burst. With these thresholds, a time slot can be assigned to a burst in advance and packet level performance can be improved. In order to evaluate its packet level performance and investigate the impact of thresholds, we also propose a queueing model of a finite buffer where a batch of packets are served in a slot of a constant length. Numerical results show that our proposed method can decrease packet loss probability and transmission delay with two thresholds. In addition, we show that our analysis results are effective to investigate the performance of the proposed method when the number of wavelengths is large.     

OBS网络中改进的重调度算法

信道调度算法是提高光突发交换(OBS)网络性能的关键技术之一.文章在重调度算法的基础上首次提出了一种改进的重调度算法,通过一次性搜索保存数据信道信息,减少了重调度处理的次数与复杂性,并能降低系统的丢包率.     

一种基于IEEE802.16无线MESH网络集中调度机制的时隙分配方法

在基于IEEE 802.16的无线Mesht网络中,时隙分配算法对网络性能有重要影响.针对现有时隙分配算法只研究上行链路且时隙分配的结果导致中继节点在转发数据时频繁在相邻时隙间进行收发切换的问题,提出了一种上下行链路通用的时隙分配方法,对于上行链路,跳数较小节点的数据优先传输,而对于下行链路,跳数较大节点的数据优先传输,在传输路径上采用逐跳传输的策略.仿真结果证明了该算法的有效性.     

Throughput-based fair bandwidth allocation in OBS networks

Fair bandwidth allocation (FBA) has been studied in optical burst switching (OBS) networks, with the main idea being to map the max-min fairness in traditional IP networks to the fair-loss probability in OBS networks. This approach has proven to be fair in terms of the bandwidth allocation for differential connections, but the use of the ErlangB formula to calculate the theoretical loss probability has made this approach applicable only to Poisson flows. Furthermore, it is necessary to have a reasonable fairness measure to evaluate FBA models. This article proposes an approach involving throughput-based-FBA, called TFBA, and recommends a new fairness measure that is based on the ratio of the actual throughput to the allocated bandwidth. An analytical model for the performance of the output link with TFBA is also proposed.     

Credit-based slot allocation for multimedia mobile ad hoc networks

This paper studies resource management for multimedia mobile ad hoc networks (MANET). In particular, we focus on providing fair scheduling with quality-of-service (QoS) support for MANET. We consider two types of flows: guaranteed and best effort flows. The goal is to satisfy the QoS requirements of guaranteed flows and to provide global fairness for best effort flows. In this paper, a credit-based fair scheduling mechanism called credit-based slot allocation protocol (CSAP) is proposed. In CSAP, nodes are logically grouped into clusters, each with a scheduler. Each scheduler assigns time slots to nodes in its cluster based on the first tier algorithm. The node scheduled to send at the next time slot then in turn assigns the time slot to a relayed flow determined by the second-tier algorithm. Each multihop flow is treated as multiple single-hop flow segments. These segments are then correlated such that a downstream segment will not be allocated a slot unless the upstream segments have all been allocated. We evaluate the performance of CSAP by simulations. The results show that CSAP meets the QoS requirements of guaranteed flows, provides global fairness for best effort flows, and improves overall system throughput.     

分布式高空气球通信网络功率分配算法

针对高空气球组网通信中干扰严重和电量供应受限的问题,提出了一种基于非合作博弈的分布式功率分配模型.通过在效用函数中增加干扰限制,保证了网络的整体信干噪比,提升了网络的通信质量;通过在效用函数中关注节点的剩余能量,使高空气球的工作时间得到延长.利用数学分析验证了模型中纳什均衡点的存在性和唯一性,并给出了纳什均衡点的求解方...     

Collision avoidance slot allocation scheme for multi-cluster wireless sensor networks

This paper introduces a collision avoidance slot allocation scheme for Time Division Multiple Access (TDMA) based Medium Access Control (MAC) in multi-cluster wireless sensor networks. TDMA MAC protocols have built-in active-sleep duty cycle that can be leveraged for limiting idle listening. Also, they can overcome the overhearing problem, thus have better energy efficiency. Enabling concurrent intra-cluster communications using a single radio channel is a key issue in TDMA MAC protocols. Using orthogonal frequency channels or different Code Division Multiple Access codes for different adjacent clusters can solve the problem at the expense of cost. In this paper, we propose a new distributed slot allocation protocol called  Coordinated   Time   Slot   Allocation (CTSA) that can reduce collisions significantly using a single radio channel. We use simulations to study the effects of different system parameters on the performance of our proposed protocol. Simulation results show that applying CTSA over clustering protocols can significantly reduce collisions. It also shows fast convergence for our proposed CTSA protocol. In this paper we apply our CTSA scheme to the Low Energy Adaptive Clustering Hierarchy protocol which forms the basis for many cluster based routing protocols. CTSA is also compared with the SRSA algorithm proposed by Wu and Biswas (Wirel Netw 13(5):691–703, 2007) by means of simulation.     

一种新的无线传感网络的时隙分配策略

时隙分配是时分多址(TDMA)接入的核心。TMDA将时间划分为若干个固定时隙,使2个干扰的节点在不同时隙内传输数据,进而降低接入碰撞率。为此,提出基于分布式TDMA的时隙分配算法。该算法以Drand算法为基础,对其进行改进。利用路由信息分配时隙,降低通信时延和传输的消息数。仿真结果表明,与Drand算法相比,提出的算法传输时延降低了约8%,传输的消息数约下降了24%。     

IEEE802.16中竞争时隙的动态分配算法

文章通过对IEEE802.16中竞争方式的请求与分配关系进行分析,提出了一种竞争时隙的动态分配方法.与固定分配方式相比,该分配方法可有效提高上行带宽的使用效率,并减小竞争请求引入的时延.仿真结果表明,在各种负载条件下,该分配算法都能较高效地使用系统的上行带宽.     

OBS中的一种原波长优先批调度算法

光突发交换网络(OBS)中心节点使用波长转换器减少突发丢失率,但波长转换器价格昂贵且技术不成熟,中心节点需要减少波长转换器的使用数目.大部分数据信道调度算法都没有考虑波长转换器数目.为此,提出一种原波长优先批调度算法基于相同波长转换器数目下进一步减少突发丢失率.仿真结果表明,这种批调度算法在波长转换器不足条件下,与其它...     

Long-term estimation-based burst control algorithm in OBS networks

By taking advantage of statistical multiplexing gain in the burst level, optical burst switching (OBS) technology enables optical Internet to handle huge volume of data in an efficient manner without requiring optical buffers in the optical domain. However, when congestion builds up in the optical network core, large amount of data might be lost. In this article, we propose an efficient optical burst control algorithm that operates based on the awareness of future burst traffic condition to eliminate the effect of congestion reaction delay. The proposed algorithm takes advantage of multiple statistics to improve the estimation accuracy.Through performance evaluation, it is verified that the proposed algorithm proactively controls inbound burst traffic so that the OBS network can stay in a stable traffic condition while keeping the network throughput high.

OBS网络中的最小间隙组调度算法

根据OBS网络的结构和特点,分析了OBS网络核心节点的数据信道调度算法,提出了一种新的数据信道调度算法--最小间隙组调度(SGGS)算法,并详细讨论了该算法的具体实现.该算法将到达核心节点的控制包分组,然后将这一组控制包按数据包到达先后的次序调度数据信道,从而达到合理调度和使用数据信道,最终实现改善整个OBS网络性能的目的.     

Dynamic subchannel and slot allocation for OFDMA networks supporting mixed traffic: upper bound and a heuristic algorithm

Optimizing resource allocation over only the frequency dimension in a single-cell OFDMA network is strictly suboptimal when heterogeneous non-real-time data users coexist. In this work we examine how to jointly exploit multi-user diversity on frequency and time domains towards maximizing cell throughput performance and satisfying individual rate and fairness QoS constraints.We develop a performance upper bound as well as an efficient heuristic algorithm for subcarrier and slot allocation which outperforms existing algorithms under polynomial complexity.     

一种基于混合门限的快速前向资源预留OBS组装算法

研究了一种以突发组装的时间门限与包长门限的乘积为混合门限的按照步长大小进行自适应调整的突发组装算法,并且当第一个IP包进入组装队列时就对突发的大小及组装时间进行预测,最大程度上降低了端到端的延迟;仿真结果表明,在进行快速前向资源预留组装的基础上引入重传机制,可以在减少端到端延时的同时降低突发丢包率,较大地提高了OBS网络的性能.     

Implicit scheduling algorithm for dynamic slot assignment inwireless ATM networks

A novel scheduling algorithm is proposed for the MAC (medium access control) protocol in wireless asynchronous transfer mode networks. The proposed algorithm has been demonstrated to be an effective means of implementing dynamic slot assignment without explicitly transmitting the dynamic parameters for variable bit rate traffic     

A prioritized resource allocation algorithm for multiple wireless body area networks

This paper presents a prioritized resource allocation algorithm to share the limited communication channel resource among multiple wireless body area networks. The proposed algorithm is designed based on an active superframe interleaving scheme, one of the coexistence mechanisms in the IEEE 802.15.6 standard. It is the first study to consider the resource allocation method among wireless body area networks within a communication range. The traffic source of each wireless body area network is parameterized using the traffic specification, and required service rate for each wireless body area networks can be derived. The prioritized resource allocation algorithm employs this information to allocate the channel resource based on the wireless body area networks’ service priority. The simulation results verified that the traffic specification and the wireless body area network service priority based resource allocation are able to increase quality of service satisfaction, particularly for health and medical services.     

A game-based algorithm for fair bandwidth allocation in Fibre-Wireless access networks

Fibre-Wireless (FiWi) access networks have been proposed as flexible and cost-effective solutions for future access networks. At the wireless mesh section, wireless routers have to forward both local traffic from directly connected users and foreign traffic from neighbour wireless routers. How to allocate resources to local and foreign traffic at each router in a balanced way, while avoiding starvation of routers requiring less resources, is a fundamental issue that must be solved so that new services emerge. Here, we develop a repeated game framework for bandwidth allocation and propose an algorithm that allocates bandwidth in a fair manner. The algorithm is able to detect over claiming routers and avoid possible denial of service that these may cause to others. Moreover, unfruitful use of resource is prevented, avoiding the forwarding of packets that would be dropped at some point later in the path, and queueing delay conditions are kept similar among local and foreign traffic. These fair network conditions open way for QoS support since it is easier to ensure the operationality of services.