Optimal scheduling of coordinated multipoint transmissions in cellular networks

In this paper, we study the optimal scheduling problem in coordinated multipoint (CoMP) transmission–based cellular networks. We consider joint transmission and coordinated scheduling together in CoMP transmission–based cellular networks and develop an optimization framework to compute the optimal max‐min throughput and the optimal scheduling of the transmissions to the users. The optimization problem is found to be a complex linear program with number of variables in for a cellular network of N users and K cells. We solve the optimization problem for several network instances using an optimization tool. The numerical results show that the optimal CoMP transmission provides a significant throughput gain over a traditional transmission. We find that in optimal scheduling the fraction time of coordinated scheduling is higher than that of joint transmission. To solve the optimization problem without any optimization tool, we propose a heuristic algorithm. The performance of the heuristic algorithm is evaluated and found to be provided throughput around 97% of the optimal throughput. Further, we extend the optimization framework to study joint scheduling and power allocation (JSPA) problem in CoMP transmission–based cellular networks. We numerically solve the JSPA problem for the network instances and demonstrate that the optimal power allocation at the base stations is not binary for a significant fraction of time of scheduling. However, the gain in max‐min throughput by the optimal JSPA technique over the optimal scheduling technique is not significant.     

Complexity of coordinated beamforming and scheduling for OFDMA based heterogeneous networks

Wireless Networks - Coordination is foreseen to be an important component of future mobile radio networks. It is especially relevant in heterogeneous networks, where high power base stations...     

A scalable joint routing and scheduling scheme for large-scale wireless sensor networks

The multihop configuration of a large-scale wireless sensor network enables multiple simultaneous transmissions without interference within the network. Existing time division multiple access (TDMA) scheduling schemes exploit gain based on the assumption that the path is optimally determined by a routing protocol. In contrast, our scheme jointly considers routing and scheduling and introduces several new concepts. We model a large-scale wireless sensor network as a tiered graph relative to its distance from the sink, and introduce the notion of relay graph and relay factor to direct the next-hop candidates toward the sink fairly and efficiently. The sink develops a transmission and reception schedule for the sensor nodes based on the tiered graph search for a set of nodes that can simultaneously transmit and receive. The resulting schedule eventually allows data from each sensor node to be delivered to the sink. We analyze our scheduling algorithm both numerically and by simulation, and we discuss the impact of protocol parameters. Further, we prove that our scheme is scalable to the number of nodes, from the perspectives of mean channel capacity and maximum number of concurrent transmission nodes. Compared with the existing TDMA scheduling schemes, our scheme shows better performance in network throughput, path length, end-to-end delay, and fairness index.     

Performance evaluation of 3D video streaming services in LTE-Advanced networks

Due to the ever growing interest of 3-dimensional (3D) technology, together with the the widespread use of new generation smartphones, netbooks, and tablets, the idea to provide 3D multimedia services also to mobile users is attracting the attention of researchers worldwide. The emerging long term evolution-advanced (LTE-A) technology seems to have all the potential to offer such kind of services but no accurate studies have been yet conducted to demonstrate this assumption. To bridge this gap, we investigate herein how the LTE-A network configuration, the traffic load, and 3D video settings may influence to the quality of all services of all active flows. We consider a heterogeneous LTE-A network composed by macro and pico cells and a number of users uniformly distributed into the scenario, that receive at the same time 3D video streams, voice flows and best-effort applications. Moreover, several objective metrics, such as the ratio of lost packets, the peak signal to noise ratio, the Structural SIMilarity, the application goodput, and packet delays, have been evaluated to show the LTE-A effectiveness in delivering 3D videos in a realistic last generation mobile environment.     

Enhancing energy-efficient sleep scheduling for Narrowband Internet of Things devices in coordinated 5G networks within smart environments

This research project takes on a crucial role in the quickly changing field of integrated 5G networks inside smart environments by concentrating on the creation of an extremely effective sleep scheduling system designed especially for Narrowband Internet of Things (NB-IoT) devices. This work introduces a unique method for precisely controlling the nodes' sleep schedules through the use of convolutional neural network (CNN) architecture, which optimizes both energy usage and operating patterns. The principal goal still stands to guarantee the extended lifetime of operation and dependability of NB-IoT devices in the larger framework of intelligent ecosystems driven by synchronized 5G networks. To achieve its objectives, the research explores a number of complex domains and employs cutting-edge technologies and techniques, such as CNN-based pattern recognition. This method's real-time component is essential since it allows for prompt modifications to sleep schedules in order to optimize energy savings. Further boosting the devices' effectiveness and flexibility is continuous contact with a central server, which guarantees that the devices are updated with the most recent data and instructions. Essentially, the main objective of this study is to greatly increase the energy economy and operational lifetime of NB-IoT devices, which will allow for stable and long-lasting IoT deployments in the context of 5G networks in intelligent settings. This advancement is not only a boon for businesses and industries leveraging IoT technology but also a substantial step toward building smarter, more energy-efficient, and resilient smart ecosystems that benefit society as a whole.     

大规模网络管理中的任务分解与调度

集中式的管理模式和简单的基于移动agent的网络管理方法都已不能满足大型网络管理的需要,为此,在给出基于多agent的网络管理框架的基础上,提出了一种基于任务依赖关系的任务分解算法,把网络管理任务分解为具有不同优先级的子任务,处于同一优先层次的子任务可以并行执行,根据子任务的优先级产生结合网络管理特点的调度策略,理论分析和实验表明:在大规模网络管理中采用任务分解技术能够提高时间效率和减轻网络负载。     

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。     

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.     

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.     

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     

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.     

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...     

The design of large-scale networks

The application of computer techniques to difficult large-scale network problems is discussed. The physical characteristics of two types of systems are described--computer-communication networks and cable television distribution systems. Two fundamental algorithms are presented, and applications to routing, reliability, and design of computer networks are given. The detailed engineering decisions that can be made by computer in the design of practical large-scale networks are illustrated by example for cable television systems. These examples are chosen to indicate the richness and difficulty of the problem of applying computers to network design.     

Inter‐cell coordinated beamforming with opportunistic scheduling

This paper proposes a distributed coordination framework with opportunistic scheduling among multiple users as opposed to the existing works on the multiple‐cell cooperative beamforming problem that deals with a single active user in each cell. In this cross‐layer design framework that deals with the beamforming in the physical layer and multiuser scheduling in the upper layer, radio resource management and inter‐cell coordination issues are jointly considered to improve the cell‐edge throughput performance by trading off their individual benefit in an optimal manner. Our simulation results demonstrated that its performance can reach up to 85% of its upper bound at the cell boundary. Copyright © 2015 John Wiley & Sons, Ltd.     

Aging analysis in large-scale wireless sensor networks

Most research on the lifetime of wireless sensor networks has focused primarily on the energy depletion of the very first node. In this study, we analyze the entire aging process of the sensor network in a periodic data gathering application. In sparse node deployments, it is observed that the existence of multiple alternate paths to a sink leads to a power law relation between connectivity to a sink and hop levels, where the probability of connection to a sink decreases in proportion to the hop level with an exponent, when device failures occur over time. Then, we provide distance-level analysis for the dense deployment case by taking into account the re-construction of a data gathering tree and workload shift caused by the energy depletion of nodes with larger workload. Extensive simulation results obtained with a realistic wireless link model are compared to our analytical results. Finally, we show through an analysis of the aging of first-hop nodes that increasing node density with a fixed radio range does not affect the network disconnection time.     

Bandwidth-satisfied multicast trees in large-scale ad-hoc networks

The purpose of this paper is to construct bandwidth-satisfied multicast trees for QoS applications in large-scale ad-hoc networks (MANETs). Recent routing protocols and multicast protocols in large-scale MANETs adopt two-tier infrastructures to avoid the inefficiency of the flooding. Hosts with a maximal number of neighbors are often chosen as backbone hosts (BHs) to forward packets. Most likely, these BHs will be traffic concentrations/bottlenecks of the network. In addition, since host mobility is not taken into consideration in BH selection, these two-tier schemes will suffer from more lost packets if highly mobile hosts are selected as BHs. In this paper, a new multicast protocol is proposed for partitioning large-scale MANET into two-tier infrastructures. In the proposed two-tier multicast protocol, hosts with fewer hops and longer remaining connection time to the other hosts will be selected as BHs. The objective is not only to obtain short and stable multicast routes, but also to construct a stable two-tier infrastructure with fewer lost packets. Further, previous MANET quality-of-service (QoS) routing/multicasting protocols determined bandwidth-satisfied routes for QoS applications. Some are implemented as a probing scheme, but the scheme is inefficient due to high overhead and slow response. On the contrary, the others are implemented by taking advantage of routing and link information to reduce the inefficiency. However, the latter scheme suffers from two bandwidth-violation problems. In this paper, a novel algorithm is proposed to avoid the two problems, and it is integrated with the proposed two-tier multicast protocol to construct bandwidth-satisfied multicast trees for QoS applications in large-scale MANETs. The proposed algorithm aims to achieve better network performance by minimizing the number of forwarders in a tree.     

大规模ASON中路由协议优化的研究

路由协议是自动交换光网络(ASON)控制平面的重要组成部分,其负责泛洪网络的链路状态信息,并进行路由计算.在ASON的实际运行过程中,路由协议存在一些不足,如占用大量数据通信网(DCN)带宽以及链路状态数据库同步时延过大等,这些问题对网络的可扩展性有较大影响.文章针对上述问题提出了路由协议的优化方案,包括为路由信息的泛洪设定阈值,以及给路由协议增加数据库自更新功能.     

Interference reduction in cognitive networks via scheduling

In this letter, we first define a cognitive network to be useful if at least one node can be scheduled to transmit without causing significant simultaneous interference to any primary user and then investigate the interaction between secondary network size and the probability of the secondary network being useful. First the size of the primary network is fixed, and we analyze how quickly the interference threshold limit of the primary network can be reduced as a function of secondary network size. Here there is a tradeoff between the rate of interference threshold reduction and the probability that the secondary network is useful which is completely characterized for Rician fading. We then allow both networks to grow simultaneously. Here the tradeoff is determined in the regime that the interference decreases sufficiently fast for Rayleigh fading. We also investigate the effect of primary channel correlation. Finally, we say that the secondary network is -useful provided at least one of any secondary nodes can be scheduled. We show that in the asymptotic regime, the probabilities of the secondary network being -useful are uniquely related and do not depend on the asymptotic behavior of the interference threshold, the rates at which the networks grow or even the distribution of the fading.