13694

12445

كارشناسي ارشد

مهندسي كامپيوتر- معماري

اصفهان: دانشگاه صنعتي اصفهان، دانشكده برق و كامپيوتر

۱۳۹۷

دوازده، ۸۵ص.: مصور، جدول، نمودار

مجيد نبي

شادرخ سماوي، علي فانيان

1397/05/08

كتابنامه

برق و كامپيوتر

مهندسي برق و كامپيوتر

ID12445

A low latency distributed scheduling algorithm for Time Slotted Channel Hopping based Networks Hajar Hajian hajar hajian@ec iut ac ir May 12 2018 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Dr Majid Nabi nabi@cc iut ac ir Abstract Wireless Sensor Networks WSNs play an important role in the Internet of Things IoTs There are several standardprotocol stacks developed for communications in such networks The IEEE 802 15 4 standard is one of the widely usedtechnologies that provides physical and Medium Access Control MAC layers for low power WSNs The new versionsof this standard introduce a MAC operational mode called Time Slotted Channel Hopping TSCH which has become apart of the IETF 6TiSCH standard protocol stack for IoT This mode makes the network more reliable by alleviating theimpact of cross technology interference and multi path fading This is achieved by employing a channel hopping technique Moreover the Time Division Multiple Access TDMA nature of the TSCH mechanism leads to efficient and deterministicuse of the RF channel resources in the WSN However the TSCH standard does not specify a scheduling mechanism forpackets transmissions in the network it is left for the upper layers in the protocol stack Since the performance of thescheduling mechanism directly influences the performance of the TSCH based networks considerable research is beingdone to develop efficient scheduling mechanisms for these networks The scheduling algorithms may be centralized ordistributed Although the centralized mechanism are able to provide optimum schedules they are slow and impose a hightraffic overhead to the network In this thesis a low latency distributed scheduler called LaDiS is proposed The mainobjective is to reduce the end to end latency of data packets and to provide low duty cycle in 6TiSCH based networks The6TiSCH stack uses the RPL routing protocol This protocol used some control packet exchanges to construct the routingtree The proposed LaDiS scheduling algorithm schedules packet transmission timing of the nodes using the available RPLinformation and the required traffic of the nodes Thus the communication overhead is very low and the scheduling isaccomplished very fast Moreover the timeslots are dedicated to different node in such a way so that the timeslot of eachparent node is after the timeslots of its children in the RPL tree This leads to a very low end to end data delivery latency On the other hand it provides the possibility for the parent nodes to perform data aggregation and integration to reduce datatraffic load in the network LaDiS is implemented and tested in MATLAB as well as the Contiki operating system Thesimulation results show that this mechanism outperforms the state of the art distributed schedulers with respect to end to endlatency and data delivery ratio while it is faster and imposes lower overhead Therefore it is a good option for WSNs withstringent latency and reliability requirements Key Words Internet of Things IoT Wireless Sensor Networks WSNs IEEE 802 15 4 Time Slotted Channel Hopping TSCH Distributed Scheduling RPL

مجيد نبي

شادرخ سماوي، علي فانيان