Najah A. Abu Ali

A performance study of uplink scheduling algorithms in point-to-multipoint WiMAX networks

The IEEE 802.16 standard defines the specifications for medium access control (MAC) and physical (PHY) layers of WiMAX networks. A critical part of the MAC layer specification is packet scheduling, which resolves contention for bandwidth and determines the transmission order of users. Evaluating the performance packet scheduling algorithms is of utmost importance towards realizing large-scale WiMAX deployment. In this paper, we conduct a comprehensive performance study of scheduling algorithms in point-to-multipoint mode of OFDM-based WiMAX networks. We first make a classification of WiMAX scheduling algorithms, then simulate a representative number of algorithms in each class taking into account that vital characteristics of the IEEE 802.16 MAC layer and OFDM physical layer. We evaluate the algorithms with respect to their abilities to support multiple classes of service, providing quality of service (QoS) guarantees, fairness amongst service classes and bandwidth utilization. To the best of our knowledge, no such comprehensive performance study has been reported in the literature. Simulation results indicate that none of the current algorithms is capable of effectively supporting all WiMAX classes of service. We demonstrate that an efficient, fair and robust scheduler for WiMAX is still an open research area. We conclude our study by making recommendations that can be used by WiMax protocol designers.

Data Management for the Internet of Things: Design Primitives and Solution

The Internet of Things (IoT) is a networking paradigm where interconnected, smart objects continuously generate data and transmit it over the Internet. Much of the IoT initiatives are geared towards manufacturing low-cost and energy-efficient hardware for these objects, as well as the communication technologies that provide objects interconnectivity. However, the solutions to manage and utilize the massive volume of data produced by these objects are yet to mature. Traditional database management solutions fall short in satisfying the sophisticated application needs of an IoT network that has a truly global-scale. Current solutions for IoT data management address partial aspects of the IoT environment with special focus on sensor networks. In this paper, we survey the data management solutions that are proposed for IoT or subsystems of the IoT. We highlight the distinctive design primitives that we believe should be addressed in an IoT data management solution, and discuss how they are approached by the proposed solutions. We finally propose a data management framework for IoT that takes into consideration the discussed design elements and acts as a seed to a comprehensive IoT data management solution. The framework we propose adapts a federated, data- and sources-centric approach to link the diverse Things with their abundance of data to the potential applications and services that are envisioned for IoT.

Quality of service in 3GPP R12 LTE-advanced

Growing demand for mobile data traffic is challenging even the capacities of next generation wireless networks. In response, operators worldwide are expanding and updating their deployment. In turn, 3GPP continues to explore ways to empower operators with features for more capable, economic, and energy-efficient networks. Toward 3GPP Release 12, focus has shifted to accommodate the inevitable traffic explosion in both magnitude and traffic types. In this work, we highlight some of the features of LTE-Advanced Release 12 relevant to improving quality of service. Specifically, we focus on solutions explored to enhance network capacity and service delivery in terms of offloading, improved services, and improved congestion control.

Measured delay distribution in a Wireless Mesh Network test-bed

A lot of work has been done to evaluate the real time applications performance over wireless networks. Some work focused on delay as a performance metric. However, no work studied the delay random behavior over a test-bed which imitates as much as possible actual operative networks. In this paper, we designed and run different experiments over heterogeneous 802.11 wireless mesh network (WMN) test-bed with a scope of studying the delay probability distribution over multihop WMN. We anticipate that by knowing the link delay distribution, we will be able to use this information to design sound algorithms to provide for QoS. For example, designing a partitioning algorithm capable of partitioning multiple end-to-end QoS requirements into link QoS requirements. We designed different experiments to measure the link and end-to-end delays over the WMN test-bed. The measured link delays are used to construct an empirical histogram. Our experiments reveal that irrespective of the number of hops along the paths and type of traffic crossing the link, the empirical histograms almost have same general shapes. The empirical histograms are fitted into different types of standard pdf distributions. We found that the best fits for almost 90% of the empirical distributions are two standard distributions: gamma and logistic.

Evaluating Uplink Schedulers in LTE in Mixed Traffic Environments

3GPPs Long Term Evolution is defined by the standardization bodys Release 8 and 9, and provides more than a substrate for 3GPPs IMT-Advanced candidate, namely LTE-Advanced, which is due to be defined in Release 10. Both LTE and LTE-Advanced have SC-FDMA in their uplink, a multi-carrier access technique requiring contiguous subcarriers allocations for each UE. No scheduling algorithm, however, is dictated by the standard and several proposals have hence been presented to implemented by vendors. A definite scheduling requirement is the support of QoS attributes of different types of uplink traffic. Our intent in this study is evaluate the connection-level performance of representative scheduling proposals, with focus on QoS aspects. Specifically, we utilize a mixed type of traffic flows and evaluate the schedulers in terms of per-user throughput, delay, packet loss and fairness.

Fair Class-Based Downlink Scheduling with Revenue Considerations in Next Generation Broadband Wireless Access Systems

The success of emerging Broadband Wireless Access Systems (BWASs) will depend, among other factors, on their ability to manage their shared wireless resources in the most efficient way. This is a complex task due to the heterogeneous nature, and hence, diverse Quality of Service (QoS) requirements of different applications that these systems support. Therefore, QoS provisioning is crucial for the success of such wireless access systems. In this paper, we propose a novel downlink packet scheduling scheme for QoS provisioning in BWASs. The proposed scheme employs practical economic models through the use of novel utility and opportunity cost functions to simultaneously satisfy the diverse QoS requirements of mobile users and maximize the revenues of network operators. Unlike existing schemes, the proposed scheme is general and can support multiple QoS classes with users having different QoS and traffic demands. To demonstrate its generality, we show how the utility function can be used to support three different types of traffic, namely best-effort traffic, traffic with minimum data rate requirements, and traffic with maximum packet delay requirements. Extensive performance analysis is carried out to show the effectiveness and strengths of the proposed packet scheduling scheme.

Efficient bandwidth management in Broadband Wireless Access Systems using CAC-based dynamic pricing

While the demand for mobile broadband wireless services continues to increase, radio resources remain scarce. Even with the substantial increase in the supported bandwidth in next generation Broadband Wireless Access Systems (BWASs), it is expected that these systems will severely suffer from congestion due to the rapid increase in demand of bandwidth intensive applications. Without efficient bandwidth management and congestion control schemes, network operators may not be able to meet the increasing demand of users for multimedia services, and hence they may suffer immense amount of revenue loss. In this paper, we propose an admission-level bandwidth management scheme consisting of Call Admission Control (CAC) and dynamic pricing. The main aim of our proposed scheme is to provide monetary incentives to users to use the wireless resources efficiently and rationally, hence, allowing efficient bandwidth management at the admission level. By dynamically determining the prices of units of bandwidth, the proposed scheme can guarantee that the arrival rates to the system are less than or equal to the optimal ones computed dynamically, hence, guaranteeing a congestion-free system. Simulation results show the effectiveness and strengths of our proposed approach.

Data management for the Internet of Things: Green directions

The technology pertaining to connecting objects together in the Internet of Things is already the focus of intensive research efforts. However, the mechanisms managing and utilizing the resulting significant volume of data from these objects has yet to match the maturity of the technology itself. The traditional approach of migrating raw data to centralized points for data storage and analysis may incur debilitating communication and energy costs, which will negatively affect the environment in the future. In this paper, we will discuss the life cycle of data within the Internet of Things and survey the current research in the data management field for the Internet of Things. The discussion will focus on the research pertaining to the optimization of communication overhead and storage mechanisms as they have the most significant impact on energy consumption. We prove the need for further analysis and addressing of issues concerning green data management systems designs for the Internet of Things.

Dynamic Bandwidth Provisioning with Fairness and Revenue Considerations for Broadband Wireless Communication

The success of emerging wireless broadband communication systems such as 3.5 G wireless cellular systems and 802.16 broadband wireless systems (WiMAX) will depend, among other factors, on their ability to manage their shared wireless resources in the most efficient way. This is a complex task due to the heterogeneous nature and, hence, diverse bandwidth requirements of applications that these communication systems support and the reliance on high speed shared channels for data delivery instead of dedicated ones. Therefore, bandwidth provisioning is crucial for the success of such communication systems. In this paper, we propose a novel dynamic bandwidth provisioning scheme for broadband wireless communication. The proposed scheme spans multiple time slots/frames and optimally allocates them to the different classes of traffic depending on their weights, the real-time bandwidth requirements of their connections, their channel quality conditions and the expected obtained revenues. Simulation results are provided to show the potential and effectiveness of our scheme.

A distributed bandwidth-guaranteed routing algorithm for point-to-multipoint VPLS virtual connections

Virtual private LAN services (VPLS) is a new layer 2 (L2) virtual private network (VPN), which allows connection of multipoint customers at the same time. Multi-protocol label switching (MPLS) technology is the most popular candidate for implementing VPLS because it supports traffic engineering (TE) functionality over the established label switching paths (LSP). However, MPLSs TE support is provided over point-to-point (P2P) LSPs. The functionality and signaling of point to multipoint (P2MP) LSPs are not supported in existing MPLS architecture. In this paper, we propose a new on line distributed routing algorithm for supporting QoS bandwidth flow guarantees. The algorithm provides TE functionality over the P2MP VPLS connections in the core MPLS networks. The on-line distributed routing algorithm maximizes the number of admitted requests by avoiding the critical links of other source-destinations sets. The critical links are identified based on the number of times the link is used to route the source-destinations set traffic and the load over the links. The algorithm does not assume any a priori knowledge of the network traffic. The proposed algorithm performance is compared to some existing algorithms such as the widest shortest path (WSP) and the Plotkin algorithms. It shows that it outperforms both algorithms by having lower blocking probability.