Resource constrained scheduling of uniform algorithms

A method for optimizing the schedule and allocation of uniform algorithms onto processor arrays is derived. The main results described in the following paper are: (1) single (integer) linear programs are given for the optimal schedule of regular algorithms with and without resource constraints, (2) the class of algorithms is extended by allowing certain non-convex index domains, (3) efficient branch and bound techniques are used such that problems of relevant size can be solved. Moreover, additional constraints such as cache memory, bus bandwidths and access conflicts can be considered also. The results are applied to an example of relevant size.     

Energy efficient transmission scheduling for delay constrained wireless networks

In this paper, we address the problem of energy efficient packet scheduling in a wireless environment. We consider a wireless transmitter which is limited by its finite battery resource. Our objective is to design a transmission schedule that maximizes battery lifetime subject to some delay constraints. To achieve this, we exploit two previously unconnected ideas: (i) channel coding can be used to conserve energy by transmitting at reduced power levels over longer durations; (ii) electro-chemical mechanisms in batteries allow them to recover energy during idle periods. While the first idea favors extending transmission durations, the second idea requires the transmitter to be idle to allow for recovery. In other words, bursty packet transmissions interspersed with idle periods extend battery life. Therefore, a strategy which is based entirely on either one or the other idea is not optimal. We provide a framework to merge the two ideas. We consider two kinds of delay constraints, one a deadline constraint and the other an average delay constraint and show that energy aware scheduling strategies for both these scenarios can result in significant energy savings.     

An efficient delay constrained scheduling scheme for IEEE 802.16 networks

In this paper, we propose a simple yet efficient delay-constrained scheduling scheme for IEEE 802.16 networks. The proposed scheduling scheme not only can satisfy delay constraints of different service types by manipulating a simple operation parameter but also can achieve a good fairness performance. An analytical model is developed to evaluate the performance in terms of inter-service time, average queue length, and mean waiting time, and is verified through extensive simulations. Furthermore, an implementation procedure of the proposed scheme is given, which reflects the scheme’s good features of the fast re-configurability and adaptability.     

Motion compensating field interpolation using a hierarchically structured displacement estimator

A motion compensating field interpolation algorithm is presented, which allows to interpolate several fields between every two transmitted fields of a digital television sequence. Using the model of translatorily displaced objects, a hierarchically structured displacement estimator is applied to cope with relatively large displacements. It provides a displacement vector with integer components for each picture element of the fields to be interpolated. A change detector is used to assure zero displacement vectors in unchanged areas. A two-coefficient spatio-temporal filter interpolates each picture element of the fields to be interpolated. By experimental evaluations, the model of pure translatorily displaced objects has proven to be sufficient to approximate many kinds of motion. The presented interpolation technique allows the unblurred reconstruction of omitted fields of television sequences, widely preserving the natural impression of motion.     

Multitrees and constrained networks

General counting formulas are given for the numbers of multitrees in a complete graph, and these are used together with a topological analysis procedure to reveal certain properties of the ideal transformer 4-terminal constraint.     

Analysis of constrained active networks

A simplified procedure for computing the transfer functions of an active filter involving single or multiple operational amplifiers is presented. Illustrative examples are given.     

Permissively structured transfinite electrical networks

Transfinite electrical networks of ranks larger than 1 have previously been defined by arbitrarily joining together various infinite extremities through transfinite nodes that are independent of the networks' resistance values. Thus, some or all of those transfinite nodes may remain ineffective in transmitting current through infinity. In this paper, transfinite nodes are defined in terms of the paths that permit currents to reach infinity. This is accomplished by defining a suitable metricd ^v on the node setN _S ^v of eachv-sectionS ^v, av-section being a maximal subnetwork whose nodes are connected by two-ended paths of ranks no larger thanv. Upon taking the completion ofN _S ^v under that metricd ^v, we identify those extremities (now calledv-terminals) that are accessible to current flows. These are used to define transfinite nodes that combine such extremities. The construction is recursive and is carried out through all the natural number ranks, and then through the first arrow rank and the first limit-ordinal rank . The recursion can be carried still further. All this provides a more natural development of transfinite networks and indeed simplifies the theory of electrical behavior for such networks.This work was partially supported by the National Science Foundation under Grant MIP-9423732.     

混合D2D蜂窝网络中基于模拟退火算法的资源调度策略

D2D通信是未来5G网络中一种近距离直通通信方式,在通信过程中,信息直接由发送端传给接收用户,而不需要经过基站的转发.在传统蜂窝网络中引入D2D通信可以极大地提升系统的总吞吐量、增大频谱资源的利用率以及降低发射终端的功耗.主要介绍了一种适用于混合D2D蜂窝网络中的资源分配方法,通过拉格朗日乘子法结合模拟退火算法实现频谱资源的分配,提出一种同时考虑信道容量和能耗的基于模拟退火算法的资源调度策略.本算法在维也纳仿真平台上经仿真验证,相比于传统贪婪优化算法,可以明显增大系统总吞吐量和频谱资源利用率.另外,算法中采用了分布式资源调度方法,D2D用户根据算法步骤自行搜索适合的目标信道并计算其发射功率,可以有效减少基站的信令开销.     

Reliability constrained routing in QoS networks

The issue of handling network failures is becoming increasingly important. In this paper, we address the problem of constrained routing by treating reliability as one of the QoS requirements. The problem is to create a feasible path from a given node to the destination such that the bandwidth and reliability requirements of the path are satisfied and the cost of the path is minimized (Reliability Constrained Least Cost Routing Problem). To solve the problem, we propose an approach which employs a novel concept, called partial protection, wherein backup paths are created for a selected set of domains in the network so as to meet the reliability constraints. The Partial Protection Approach (PPA) has two steps: Primary Path Creation and Backup Path Creation if necessary. To implement PPA, we propose three scalable two-pass resource reservation schemes, viz., Conservative, Optimistic, and Hybrid schemes. These schemes differ depending on whether the backup paths are created during the forward pass, reverse pass, or both. We evaluate the performance of the proposed schemes for dynamic multicast groups with different bandwidth and reliability requirements using average call acceptance rate and average tree cost as performance metrics. Our studies show that group dynamics and reliability requirements have significant impact on the performance of the schemes.     

云边协同中的资源调度优化

随着业务类型的丰富和多样化,低时延、高带宽、数据私密性、高可靠性等成为业务普遍的要求。边缘计算、雾计算、分布式云、算力网络等方案相继被提出,并在产学研各界引发了深度的研究和探索。针对“多级的算力分布以及算力的协同将是未来算力结构的主流”这一观点,产业内外达成了共识,算力管理、分配、调度等与资源优化相关的问题也成为当下的研究热点和重点攻关方向。为此,面向未来的算力供给结构,首先描述了学术界、产业界资源调度优化问题的最新进展,总结了当前的主要方法论和工程实施架构;然后,针对两种典型的云边协同场景,从场景拆分、调度目标、求解方案依次进行分析,给出了适应场景特性的资源调度优化参考方案。     

Resource scheduling scheme for 5G mmWave CP-OFDM based wireless networks with delay and power allocation optimizations

In this paper, to optimize the average delay and power allocation (PA) for system users, we propose a resource scheduling scheme for wireless networks based on Cyclic Prefix Orthogonal Frequency Division Multiplexing (CP-OFDM) according to the first fifth-generation standards. For delay minimization, we solve a throughput maximization problem that considers CP-OFDM systems with carrier aggregation (CA). Regarding PA, we consider an approach that involves maximizing goodput using an effective signal-to-noise ratio. An algorithm for jointly solving delay minimization through computation of required user rates and optimizing the power allocated to users is proposed to compose the resource allocation approach. In wireless network simulations, we consider a scenario with the following capabilities: CA, 256-Quadrature Amplitude Modulation, millimeter waves above 6 GHz, and a radio frame structure with 120 KHz spacing between the subcarriers. The performance of the proposed resource allocation algorithm is evaluated and compared with those of other algorithms from the literature using computational simulations in terms of various Quality of Service parameters, such as the throughput, delay, fairness index, and loss rate.     

无线网络中的分组调度算法

探讨了将有线网络的分组调度算法引入无线网络需要改进的事项,分析了公平排队算法,建立了一个基本的无线分组调度模型,并综述了一些目前存在的无线分组调度算法。     

Implementing scheduling algorithms in high-speed networks

The fluid generalized processor sharing (GPS) algorithm has desirable properties for integrated services networks and many packet fair queueing (PFQ) algorithms have been proposed to approximate GPS. However, there have been few high-speed implementations of PFQ algorithms that can support a large number of sessions with diverse rate requirements and at the same time maintain all the important properties of GPS. The implementation cost of a PFQ algorithm is determined by: (1) computation of the system virtual time function; (2) maintenance of the relative ordering of the packets via their timestamps (scheduling); and (3) regulation of packets based on eligibility time, in some algorithms. While most of the recently proposed PFQ algorithms reduce the complexity of computing the system virtual time function, the complexity of scheduling and traffic regulation is still a function of the number of active sessions. In addition, while reducing the algorithmic or asymptotic complexity has been the focus of most analysis, it is also important to reduce the complexity of basic operations in order for the algorithm to run at high speed. We develop techniques to reduce both types of complexities for networks of both fixed and variable size packets. Regulation and scheduling are implemented in an integrated architecture that can be viewed as logically performing sorting in two dimensions simultaneously. By using a novel grouping architecture, we are able to perform this with an algorithmic complexity independent of the number of sessions in the system at the cost of a small controllable amount of relative error. To reduce the cost of basic operations, we propose a hardware-implementation framework and several novel techniques that reduce the on-chip memory size, off-chip memory bandwidth, and off-chip access latency. The proposed implementation techniques have been incorporated into commercial ATM switch and IP router products     

Queue-aware scheduling in full-duplex wireless networks

Wireless Networks - Contemporary progress in telecommunication technologies have made full-duplex wireless communications feasible. The latter promise to double the capacity of wireless networks by...     

Interference-aware broadcast scheduling in wireless networks

In this paper, we study the Interference-Aware Broadcast Scheduling problem, where all nodes in the Euclidean plane have a transmission range and an interference range equal to r and α r for α ? 1, respectively. Minimizing latency is known to be NP-Hard even when α = 1. The network radius D, the maximum graph distance from the source to any node, is also known to be a lower bound.We formulate the problem as integer programs (IP) and optimally solve moderate-size instances. We also propose six variations of heuristics, which require no pre-processing of inputs, based on the number of receivers gained by each additional simultaneous transmitting node. The experimental results show that the best heuristics give solutions that exceed the optimal solutions by only 13–20%. Further, an O(αD) schedule is proven to exist yielding an O(α) approximation algorithm.     

Fair scheduling in wireless packet networks

Fair scheduling of delay and rate-sensitive packet flows over a wireless channel is not addressed effectively by most contemporary wireline fair-scheduling algorithms because of two unique characteristics of wireless media: (1) bursty channel errors and (2) location-dependent channel capacity and errors. Besides, in packet cellular networks, the base station typically performs the task of packet scheduling for both downlink and uplink flows in a cell; however, a base station has only a limited knowledge of the arrival processes of uplink flows. We propose a new model for wireless fair-scheduling based on an adaptation of fluid fair queueing (FFQ) to handle location-dependent error bursts. We describe an ideal wireless fair-scheduling algorithm which provides a packetized implementation of the fluid mode, while assuming full knowledge of the current channel conditions. For this algorithm, we derive the worst-case throughput and delay bounds. Finally, we describe a practical wireless scheduling algorithm which approximates the ideal algorithm. Through simulations, we show that the algorithm achieves the desirable properties identified in the wireless FFQ model     

Downlink scheduling optimization in CDMA networks

The problem of allocating radio resources in the downlink of a code-division multiple access (CDMA) network is studied. The modulation and coding schemes, numbers of multicodes, and transmit powers used for all mobile stations (MS) are jointly chosen so as to maximize the total transmission bit rate, subject to certain constraints. Based on the discrete and nonlinear nature of the proposed model, a mixed-integer nonlinear programming optimization problem is formulated. It is shown that the optimal allocation generally involves simultaneous transmissions to several MS. A scheduler which uses knowledge of MS traffic loads is also proposed and shown to yield a significant improvement in throughput.     

QoS-guaranteed packet scheduling in wireless networks

To guarantee the quality of service (QoS) of a wireless network, a new packet scheduling algorithm using cross-layer design technique is proposed in this article. First, the demand of packet scheduling for multimedia transmission in wireless networks and the deficiency of the existing packet scheduling algorithms are analyzed. Then the model of the QoS-guaranteed packet scheduling (QPS) algorithm of high speed downlink packet access (HSDPA) and the cost function of packet transmission are designed. The calculation method of packet delay time for wireless channels is expounded in detail, and complete steps to realize the QPS algorithm are also given. The simulation results show that the QPS algorithm that provides the scheduling sequence of packets with calculated values can effectively improve the performance of delay and throughput.     

Modular static scheduling of synchronous data-flow networks

This paper addresses the question of producing modular sequential imperative code from synchronous data-flow networks. Precisely, given a system with several input and output flows, how to decompose it into a minimal number of classes executed atomically and statically scheduled without restricting possible feedback loops between input and output?Though this question has been identified by Raymond in the early years of Lustre, it has almost been left aside until the recent work of Lublinerman, Szegedy and Tripakis. The problem is proven to be intractable, in the sense that it belongs to the family of optimization problems where the corresponding decision problem—there exists a solution with size c—is NP-complete. Then, the authors derive an iterative algorithm looking for solutions for c=1,2,… where each step is encoded as a satisfiability (SAT) problem.Despite the apparent intractability of the problem, our experience is that real programs do not exhibit such a complexity. Based on earlier work by Raymond, the current paper presents a new encoding of the problem in terms of input/output relations. This encoding simplifies the problem, in the sense that it rejects some solutions, while keeping all the optimal ones. It allows, in polynomial time, (1) to identify nodes for which several schedules are feasible and thus are possible sources of combinatorial explosion; (2) to obtain solutions which in some cases are already optimal; (3) otherwise, to get a non trivial lower bound for c to start an iterative combinatorial search. The method has been validated on several industrial examples.The solution applies to a large class of block-diagram formalisms based on atomic computations and a delay operator, ranging from synchronous languages such as Lustre or Scade to modeling tools such as Simulink.     

Optimal scheduling of handoffs in cellular networks

The phenomenon of hard handoffs (as applicable to FDMA- and TDMA-based networks) as well as soft handoffs (as applicable to DS/CDMA-based networks) is formulated as stochastic optimization problems. The signals received by a mobile user are treated as stochastic processes with associated rewards, which are functions of some measurable characteristics of the received signals, while the handoff is associated with a switching penalty. This formulation captures the trade-offs involved in handoffs in a flexible manner and captures many facets of popular cellular communication systems in use currently. Using dynamic programming, necessary and sufficient conditions for determining the optimal base station(s) the mobile should be associated with during each decision epoch are derived. For the cases where the above-mentioned necessary and sufficient conditions fail to determine an optimal decision, “limited lookahead” arguments are used for determining handoff decisions. The decisions are taken in a decentralized manner, which makes its implementation easier compared to centralized algorithms. Simulation results show that for the hard handoffs, performance gain by the proposed algorithm over the simpler threshold algorithms proposed in the literature is small; however, for the case of soft handoffs, the proposed algorithm offers considerable improvement over the algorithm proposed in the IS-95 standard