Interest in broadband wireless access (BWA) has been growing due to increased user mobility and the need for data access at all times. IEEE 802.16e based WiMAX networks promise the best available quality of experience for mobile data service users. Unlike wireless LANs, WiMAX networks incorporate several quality of service (QoS) mechanisms at the Media Access Control (MAC) level for guaranteed services for data, voice and video. The problem of assuring QoS is basically that of how to allocate available resources among users in order to meet the QoS criteria such as delay, delay jitter and throughput requirements. IEEE standard does not include a standard scheduling mechanism and leaves it for implementer differentiation. Scheduling is, therefore, of special interest to all WiMAX equipment makers and service providers. This paper discusses the key issues and design factors to be considered for scheduler designers. In addition, we present an extensive survey of recent scheduling research. We classify the proposed mechanisms based on the use of channel conditions. The goals of scheduling are to achieve the optimal usage of resources, to assure the QoS guarantees, to maximize goodput and to minimize power consumption while ensuring feasible algorithm complexity and system scalability.

https://www.cse.wustl.edu/~jain//papers/ftp/sched.pdf

Scheduling in IEEE 802.16e mobile WiMAX networks: key issues and a survey

Internet protocol television (IPTV) will be the killer application for the next-generation Internet and will provide exciting new revenue opportunities for service providers. However, to deploy IPTV services with a full quality of service (QoS) guarantee, many underlying technologies must be further studied. This article serves as a survey of IPTV services and the underlying technologies. Technical challenges also are identified.

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Internet Protocol Television (IPTV): The Killer Application for the Next-Generation Internet

This paper describes the design and implementation of a network virtualization substrate (NVS ) for effective virtualization of wireless resources in cellular networks. Virtualization fosters the realization of several interesting deployment scenarios such as customized virtual networks, virtual services, and wide-area corporate networks, with diverse performance objectives. In virtualizing a base station's uplink and downlink resources into slices, \ssr NVS meets three key requirements-isolation, customization, and efficient resource utilization-using two novel features: 1) NVS introduces a provably optimal slice scheduler that allows existence of slices with bandwidth-based and resource-based reservations simultaneously; and 2) NVS includes a generic framework for efficiently enabling customized flow scheduling within the base station on a per-slice basis. Through a prototype implementation and detailed evaluation on a WiMAX testbed, we demonstrate the efficacy of \ssr NVS. For instance, we show for both downlink and uplink directions that \ssr NVS can run different flow schedulers in different slices, run different slices simultaneously with different types of reservations, and perform slice-specific application optimizations for providing customized services.

NVS: a substrate for virtualizing wireless resources in cellular networks

Since its formal introduction to IP networks in 1993 as a viable complementary approach for congestion control, there has been a steady stream of research output with respect to Active Queue Management (AQM). This survey attempts to travel the trajectory of AQM research from 1993 with the first algorithm, Random Early Detection (RED), to current work in 2011. In this survey we discuss the general attributes of AQM schemes, and the design approaches taken such as heuristic, control-theoretic and deterministic optimization. Of interest is the role of AQM in QoS provisioning particularly in the DiffServ context, as well as the role of AQM in the wireless domain. For each section, example algorithms from the research literature are presented.

Active Queue Management: A Survey

Scheduling solution for the IEEE 802.16 base station

IEEE 802.16 standard defines the wireless broadband access network technology called WiMAX. WiMAX introduces several interesting advantages, and one of them is the support for QoS at the MAC level. For these purposes, the base station must allocate slots based on some algorithm. We propose a simple, yet efficient, solution for the WiMAX base station that is capable of allocating slots based on the QoS requirements, bandwidth request sizes, and the WiMAX network parameters. To test the proposed solution, we have implemented the WiMAX MAC layer in the NS-2 simulator. Several simulation scenarios are presented that demonstrate how the scheduling solution allocates resources in various cases. Simulation results reveal the proposed scheduling solution is ensures the QoS requirements of all the WiMAX service classes and shares fairly free resources achieving the work-conserving behaviour.

Ensuring the QoS requirements in 802.16 scheduling

The IEEE 802.16 technology defines the ARQ mechanism that enables a connection to resend data at the MAC level if an error is detected. In this paper, we analyze the key features and parameters of the 802.16 ARQ mechanism. In particular, we consider a choice for the ARQ feedback type, an algorithm to build block sequences, a scheduling of the ARQ feedbacks and retransmissions, the ARQ block rearrangement, ARQ transmission window and ARQ block size. We run a number of simulation scenarios to study these parameters and how they impact a performance of application protocols. The simulation results reveal that the ARQ mechanism and its correct configuration play an important role in transmitting data over wireless channels in the IEEE 802.16 networks.

Performance analysis of the ieee 802.16 arq mechanism

In the IEEE 802.16 the number of errors and the MAC PDU size have an impact on the performance of the network. We present a way to estimate the optimal PDU size and we run a number of simulation scenarios to study these parameters and how they impact on the performance of application protocols. The simulation results reveal that the channel bit error rate has a major impact on the optimal PDU size in the IEEE 802.16 networks. Also, the ARQ block rearrangement influences the performance.

Optimal MAC PDU Size in IEEE 802.16

IEEE 802.16 standard defines the wireless broadband access network technology called WiMAX which introduces several interesting advantages including its the support for quality of service (QoS) at the MAC layer. Its several features, such as multicast polling support the base station (BS) to provide the QoS guarantees for subscriber stations (SSs). The specification, however, does not define very exactly how this optional multicast polling technique should be used. We propose a way to use this feature on the base stations and also suggest an addition to the specification, to serve several different delay requirements. To test the proposed solution and the performance of the multicast polling in general, we have run several simulation scenarios in the NS-2 simulator. Voice over IP (VoIP) is considered as a specific application, since its tight delay requirements benefit most from the positive effect of multicast polling.

O. Alanen

Papers

Ensuring the QoS requirements in 802.16 scheduling

Scheduling solution for the IEEE 802.16 base station

Performance analysis of the ieee 802.16 arq mechanism

Optimal MAC PDU Size in IEEE 802.16

Multicast polling and efficient voip connections in ieee 802.16 networks