Minimum bandwidth reservations for periodic streams in wireless real time systems
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This document discusses a method for determining minimum bandwidth reservations for periodic streams in wireless real-time systems, focusing on improving efficiency and energy consumption through reservation-based channel access. It addresses the need for real-time constraints for individual nodes and proposes a generic algorithm applicable to various scheduling policies, including fixed priority, EDF, and FIFO, with a detailed evaluation of their efficiencies. Additionally, it outlines a modular approach to bandwidth reservation management, highlighting the significance of maintaining quality of service for real-time applications.
Minimum bandwidth reservations for periodic streams in wireless real time systems
- 1. MINIMUM BANDWIDTH RESERVATIONS FOR PERIODIC STREAMS IN WIRELESS REAL-TIME SYSTEMS ABSTRACT Reservation-based (as opposed to contention-based) channel access in WLANs provides predictable and deterministic transmission and is therefore able to provide timeliness guarantees for wireless and embedded real-time applications. Also, reservation-based channel access is energy efficient since a wireless adaptor is powered on only during its exclusive channel access times. While scheduling for Quality of Service at the central authority (e.g., base station) has received extensive attention, the problem of determining the actual resource a requirement of an individual node in a wireless real-time system has been largely ignored. This work aims at finding the minimum channel bandwidth reservation that meets the real-time constraints of all periodic streams of a given node. Keeping the bandwidth reservation of a node to a minimum leads to reduced energy and resource requirements and leaves more bandwidth for future reservations by other nodes. To obtain a solution to the minimum bandwidth reservation problem, we transform it to a generic uniprocessor task schedulability problem, which is then addressed using a generic algorithm. This algorithm works for a subclass of priority-driven packet scheduling policies, including three common ones: Fixed priority, EDF, and FIFO. Moreover, we then specialize the generic algorithm to these three policies according to their specific characteristics. Their computation complexities and bandwidth reservation efficiencies are evaluated and guidelines for choosing scheduling policies and stream parameters are presented.
- 2. Proc ess Flow EXISTING SYSTEM: The problem of determining the actual resource while bandwidth transfer some amount of data. At a time we transfer large number of data means the bandwidth energy becomes low. Sometimes, data will be loss. A requirement of an individual node in a wireless real-time system has been largely ignored.
- 3. PROPOSED SYSTEM: In proposed System, we first reserve the bandwidth. If server transfer the data means, base station check the new data is to be already reserved or not. If it is reserved a channel means the data to be assigned to going. Otherwise, the data to be blocked. So, this work aims at finding the minimum channel bandwidth reservation that meets the real-time constraints of all periodic streams of a given node. Keeping the bandwidth reservation of a node to a minimum leads to reduced energy and resource requirements and leaves more bandwidth for future reservations by other nodes. MODULES: 1. Bandwidth Reservation 2. Fixed Priority 3. FIFO (First- in First- out) 4. EDF (Earliest Deadline First) 5. Traffic Analysis MODULES DESCRIPTION 1. Bandwidth Reservation Resource reservations to ensure contention free accesses. This is achieved through a central authority at a base station (BS) that regulates the channel accesses of individual nodes. Here, the BS takes control of the channel and starts polling each of the nodes in a pre-determined order (e.g., round-robin). Upon reception of a polling frame, a node gains access to the channel. The HCCA mode defined in the IEEE 802.11e standard is an example of a protocol which adopts the reservation-based
- 4. channel access approach to enhance the QoS support for real-time applications in wireless environments. 2. Fixed Priority It is a scheduling system commonly used in real-time systems. With fixed priority pre-emptive scheduling, the scheduler ensures that at any given time, the processor executes the highest priority task of all those tasks that are currently ready to execute. Bandwidth check the timeliness of the stream cannot be affected by the other streams. Every released stream with the synchronous interval needs to be checked. Only synchronous busy interval must be checked. All streams are released before this instant have completed and every stream in release a work at this instant. The interval ends with the completion of all released work within the priority. 3. FIFO (First- in First- out) In FIFO only released finished function. It checks completely time-demand function. The work will be finished/unfinished portion function and completion time function can be customized. The periodic streams are generated with random parameters within given ranges and distributions. It related to ways of organizing and manipulation of data relative to time and prioritization. This expression describes the principle of a queue processing technique or servicing conflicting demands by ordering process by first-come, first-served (fcfs) behavior: what comes in first is handled first, what comes in next waits until the first is finished, analogous to the behavior of persons standing in line, where the persons
- 5. leave the queue in the order they arrive, or waiting one's turn at a traffic control signal. 4. EDF (Earliest Deadline First) It is a dynamic scheduling. It is used in real-time operating systems. it places processes in a priority queue. Whenever a scheduling event occurs (task finishes, new task released, etc.) the queue will be searched for the process closest to its deadline. This process is the next to be scheduled for execution. 5. Traffic Analysis It can be performed even when the data are reserved and cannot be reserved. In general, the greater the number of data observed, or even intercepted and stored, the more can be inferred from the traffic. System Requirements: Hardware Requirements: System : Pentium IV 2.4 GHz. Hard Disk : 40 GB. Floppy Drive : 1.44 Mb.
- 6. Monitor : 15 VGA Colour. Mouse : Logitech. Ram : 512 Mb. Software Requirements: Operating system : - Windows XP. Coding Language : ASP.Net with C#. Data Base : SQL Server 2005