696 research outputs found
New contention resolution schemes for WiMAX
Abstract—The use of Broadband Wireless Access (BWA) technology is increasing due to the use of Internet and multimedia applications with strict requirements of end–to–end delay and jitter, through wireless devices. The IEEE 802.16 standard, which defines the physical (PHY) and the medium access control (MAC) layers, is one of the BWA standards. Its MAC layer is centralized basis, where the Base Station (BS) is responsible for assigning the needed bandwidth for each Subscriber Station (SS), which requests bandwidth competing between all of them. The standard defines a contention resolution process to resolve the potential occurrence of collisions during the requesting process. In this paper, we propose to modify the contention resolution process to improve the network performance, including end–to–end delay and throughput
Wireless broadband access: WiMAX and beyond - Investigation of bandwidth request mechanisms under point-to-multipoint mode of WiMAX networks
The WiMAX standard specifies a metropolitan area broadband wireless access air interface. In order to support QoS for multimedia applications, various bandwidth request and scheduling mechanisms are suggested in WiMAX, in which a subscriber station can send request messages to a base station, and the base station can grant or reject the request according to the available radio resources. This article first compares two fundamental bandwidth request mechanisms specified in the standard, random access vs. polling under the point-to-multipoint mode, a mandatory transmission mode. Our results demonstrate that random access outperforms polling when the request rate is low. However, its performance degrades significantly when the channel is congested. Adaptive switching between random access and polling according to load can improve system performance. We also investigate the impact of channel noise on the random access request mechanism
WLC22-4: Efficient request mechanism usage in IEEE 802.16
IEEE 802.16 protocols for metropolitan broadband wireless access systems have been standardized recently. According to the standard, a subscriber station can deliver bandwidth request messages to a base station by numerous methods. This paper provides both the simulation and analytical models for the investigation of specified random access method, which is compared with centralized polling and station- grouping mechanisms. Based on the assumptions of Bernoulli request arrival process and ideal channel conditions, the mean delay of a request transmission is evaluated for varying number of transmission opportunities and different arrival rates
Efficient Resource Management Mechanism for 802.16 Wireless Networks Based on Weighted Fair Queuing
Wireless Networking continues on its path of being one of the most commonly used means of communication. The evolution of this technology has taken place through the design of various protocols. Some common wireless protocols are the WLAN, 802.16 or WiMAX, and the emerging 802.20, which specializes in high speed vehicular networks, taking the concept from 802.16 to higher levels of performance. As with any large network, congestion becomes an important issue. Congestion gains importance as more hosts join a wireless network. In most cases, congestion is caused by the lack of an efficient mechanism to deal with exponential increases in host devices. This can effectively lead to very huge bottlenecks in the network causing slow sluggish performance, which may eventually reduce the speed of the network. With continuous advancement being the trend in this technology, the proposal of an efficient scheme for wireless resource allocation is an important solution to the problem of congestion. The primary area of focus will be the emerging standard for wireless networks, the 802.16 or “WiMAX”. This project, attempts to propose a mechanism for an effective resource management mechanism between subscriber stations and the corresponding base station
Performance Study of Bandwidth Request Mechanisms in IEEE 802.16e Networks
WiMAX (Worldwide Interoperability for Microwave Access) is the IEEE 802.16 standards-based wireless technology that provides fixed and mobile Internet access for Metropolitan
Area Networks (MAN). The IEEE 802.16 std. includes medium access control (MAC) and physical (PHY) layer pecifications and is consider to be a promising technology. Bandwidth reservation is employed to provide quality of service (QoS) to guarantee different services specified in the standard. A bandwidth request/grant scheme is defined in the IEEE 802.16 standard. There are two types of
bandwidth request (BR) mechanisms, i.e., polling
and contention resolution, which are defined in the
standard. As specified, connections belonging to
scheduling classes of extended real-time polling
service, non-real-time polling service, and best effort
have options to make BRs via both mechanisms,
depending on the scheduling decision made by the
base station (BS). This paper attempts the
comparative study of BR mechanisms for different
service classes defined in the standard
WiMAX: Performance Analysis and Enhancement of Real-time Bandwidth Request
This paper carried out a study on the bandwidth request for real-time polling services. In our study, we discovered that although the base station granted the subscriber station an allocation to send the bandwidth request, the subscriber station may not be able to allocate the bandwidth request to the allocation. It is due to processing
delay and multicast polling in the subscriber station, which results the bandwidth request being padded unintentionally. The loss of bandwidth requests will cause the degradation of the real-time polling service performance. Therefore, we propose a scheme to overcome this problem. The results of the experiment show that the proposed scheme improves the performance of real-time polling services
A Fair and Efficient Packet Scheduling Scheme for IEEE 802.16 Broadband Wireless Access Systems
This paper proposes a fair and efficient QoS scheduling scheme for IEEE
802.16 BWA systems that satisfies both throughput and delay guarantee to
various real and non-real time applications. The proposed QoS scheduling scheme
is compared with an existing QoS scheduling scheme proposed in literature in
recent past. Simulation results show that the proposed scheduling scheme can
provide a tight QoS guarantee in terms of delay, delay violation rate and
throughput for all types of traffic as defined in the WiMAX standard, thereby
maintaining the fairness and helps to eliminate starvation of lower priority
class services. Bandwidth utilization of the system and fairness index of the
resources are also encountered to validate the QoS provided by our proposed
scheduling scheme
A Survey on Scheduling in IEEE 802.16 Mesh Mode
Cataloged from PDF version of article.IEEE 802.16 standard (also known as WiMAX)
defines the wireless broadband network technology which aims
to solve the so called last mile problem via providing high
bandwidth Internet even to the rural areas for which the cable
deployment is very costly. The standard mainly focuses on the
MAC and PHY layer issues, supporting two transmission modes:
PMP (Point-to-Multipoint) and mesh modes. Mesh mode is an
optional mode developed as an extension to PMP mode and it
has the advantage of having an improving performance as more
subscribers are added to the system using multi-hop routes. In
802.16 MAC protocol, mesh mode slot allocation and reservation
mechanisms are left open which makes this topic a hot research
area. Hence, the focus of this survey will mostly be on the mesh
mode, and the proposed scheduling algorithms and performance
evaluation methods
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