Admission Control and Slot Reservation of Hybrid Coordination Function in a Wireless LAN Communication Protocol

Autor: Tien-Chih Wang, 王天智
Rok vydání: 2001
Druh dokumentu: 學位論文 ; thesis
Popis: 89
This work focuses on admission control and resource allocation in the wireless LAN. We propose a Hybrid Coordination Function (HCF) mechanism for the multimedia traffic first. Our HCF is an extension of Reservation CSMA/CA, which is derived from PRMA (Packet Reservation Multiple Access). The features of HCF are multi-slots allocation, infrastructure network, and threshold algorithm. multi-slots allocation means that a station may request for multi-slots according to its requirement. Under the architecture of HCF, we propose a suite of system with resource management and admission control. This system can be separated into three parts, one is admission control, another is earning-oriented slots allocation mechanism, and the other is slots re-assignment. By predicting according to the arrival rate, the admission control can estimate the number of the incoming requests at the next frame, and then combine these estimated requests with those requests that have arrived at current frame, and store the result after combined to a request-list. Depending on our proposed sorting manner, sort the request-list, and then decide which request can be admitted according to the quota in order. After decision of admission control, AP (Access Point) decides to allocate how many time slots to the admitted request according to quota and the QoS parameters of the admitted request. If the remaining resource of system is adequate to satisfy the requirements of the request, AP will fulfill that requirement. Otherwise, if the reward brought from the requesting station is greater than the penalty of elongating other stations in the system currently, AP will re-assign the time slots to the degraded stations for the requesting station. On the other hand, AP only can allocate the remaining resource to this requesting station. In aspect of slots re-assignment, we propose two kinds of methods, and will compare with each other in the simulation. At the last two chapters of this paper, we will compare the system earnings, mean delay, and utilization of our proposed algorithm with the FIFO (First In First Out) system, and analyze the simulation results. Chapter 2. Background 8 2.1 CSMA/CA 9 2.2 PRMA 11 2.3 Reservation CSMA/CA 12 2.4 PCF (Point Coordination Function) 13 Chapter 3. Hybrid Coordination Function 15 3.1 Hybrid Coordination Function Structure 16 3.2 HCF Frame Cycle 17 3.3 Beacon format 18 3.4 Reservation Procedure 19 3.5 Frame Type 20 3.6 ACK Occasion 20 Chapter 4. Earning-oriented Slots Allocation and Admission Control 21 4.1 System Modeling 22 4.2 QoS Parameters 23 4.3 The Degradation Process 23 4.4 Admission Control Algorithm 25 4.5 Earning-oriented Slots Allocation Mechanism 26 4.6 Slots Re-assignment 29 4.7 Arrival 30 Chapter 5. Simulation and Results 33 5.1 The comparison of two slots re-assignment methods 33 5.2 The comparison of earning-oriented slots allocation and FIFO 34 5.3 The comparison of with admission control and without admission control 37 Chapter 6. Conclusions 42 References 43
Databáze: Networked Digital Library of Theses & Dissertations
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