Guided byProf. Chetana V. Samundre , Rajshri Suryavanshi, Abstract-Wireless sensor network(WSN)consist of compact distributed self-organizing wireless nodes with small amountof CPU memory, low processing power and low battery capacity. The wirelessnodes generates different types of data packets such as real time and non-realtime data packets because it sense environmental situations. WSN uses most existing packetsscheduling system i.e. First come first serve(FCFS).
In FCFS concept the datapackets which enter the node first will leave the node first. In this processthere might be starvation of real time data packets because data packets areprocessed according to the time but they are not processed according topriority.Scheduling different type of packagein WSN is highly important since it ensure deliver of different type of packetsbased on their priority and fairness with minimum latency. Disha Kathane, Tejashree Pandit INTRODUCTIONWireless sensor networks (WSN)consist of more than hundreds of small spatially distributed autonomous devicesusing sensors called sensor nodes to monitor the physical and environmentalsituations such as sound vibration, temperature, pressure, motion and intensityof light. WSN has gained a great value and importance due to flexibility,cheaper implementation cost, mobility etc. The sensor networks are expected toplay increasingly important role in future especially in monitoring andmilitary applications on large scales and it consists of small and inexpensivesensor nodes that have limited memory, limited computing power, and thatoperate using batteries. Scheduling of different packets atthe sensor nodes is very important as ensures the delivery of the data packeton the priority basis.
The sensed data may be real time or non-real time.Highest priority should be given to real time data sense by the node compare tonon-real time data packet. Sometime the nodes may be put to sleep mode, whenthere is no data packet available and as soon as the data packet arrives at thenode is putted into wake mode. This reduce the sensor node energy consumption.Fig.1: Diagram of energy efficient multilevel priority packet scheduling scheme forWSNSensor nodes are smart, small in sizelight weight that monitor physical and environmental situations.
The datasensed at the wireless sensor nodes is to be sent to a base station nodes viaLAN connection that connects all the nodes of WSN that uses very less bandwidthbase station collect the data from various nodes using single hope transmissionand sometimes multi hope transmission. The packet scheduling scheme for WSN, in whichovercome all drawback occurred in existing scheduling algorithm. The DMP packetscheduling scheme for WSN, in which sensor nodes are virtually organizedhierarchical structure.
In DMP packet scheduling scheme for WSN, where each node maintains three level intoits queue for three different types of data packets. This is because weclassify data packets as (1) real time (highest or priority1), (2) non realtime remote packets i.e., packet that arrive from the sensors nodes at lowerlevel (priority 2), and (3) non real time local packet(lowest priority 3).Non-real time data packets are classified based on the location on sensor nodesto balance to end-to-end delay of data packets that are generated at differentlocations. Non-real time data traffic with the same priority are processedusing the shortest job first (SJF) scheduler scheme since it is very efficientin turns of average task waiting time.RELATED WORK Inthis section, we define the following terminologies and factors that are used in packet scheduling scheme.
EarliestDeadline First (EDF): -Whenevera number of data packets are available at the node and each packet has adeadline within which it should be sent to base station. The data packet whichhas the earliest deadline is sent first. Data that have travelled the longest distance from the source node tobase station and have the shortest deadline, are given highest priority. If thedeadline of a particular data packet expires, the most suitable data packetsare send at an intermediate node.First Come First Serve (FCFS):- Thefirst come, first served scheduling system is the simplest scheduling system inwhich packets are processed as they come.
It is the method that was used to support real-time communication. Inthis scheduling system it might be possible that the data packet that shouldreach base station as early as possible take time. Therefore to avoid timeconsumption the data packets are prioritized. Packet Type Packet scheduling schemes can be classified based onthe types of data packets, which are as follows.Real-timedata packets: – Packetsat sensor nodes should be scheduled based on their types and priorities.Real-time data packets are considered as the highest priority packets among alldata packets that are present at the node.
Hence, they are processed with thehighest priority and delivered to the base station with a minimum possibleend-to-end delay. Non-real-timedata packets:- Non-real time data packets have lower priority thanreal-time data packets. They are hence delivered to BS either using first comefirst serve or shortest job first basis when no real-time packet exist sensornode.
PRELIMINARIESInThis section, we define some of the Terminologies and genera assumptions whichare used in designing the Dynamic Multilevel priority (DMP) PacketScheduling Scheme.AssumptionsWe make some of the followingassumptions to design and implement DMP packet Scheduling Scheme.Only real time data packets andnon-real time data packets are present in the data traffic medium for e.g.non-real –time data sensed by temperature data and real-time data body sensors.Both types of data packets are of samesize i.e. real-time and non-real –time.
In the network all sensors node aretime synchronized.For real- time data there is no dataaggregation is performed at intermediate nodes.Depending upon the Number of hop countsnodes are considered located at different levels.By Using TDMA scheme timeslots arelocated to nodes.
Each sensor nodes have ready queuewhich is divided into three individual queues only (For real –time data pr1,For non-real-time data pr2 andnon-real-time local data pr3.The length is variable for data queuesin sensor nodes. For instant pr1 length is smaller than pr2 and pr3 queues aresame. TERMINOLOGIESInthis section, we described the following factors and terminologies which areimportant in designing the DMP packet Scheduling scheme.RoutingprotocolRoutingprotocol in which network is a virtually arrange into a hierarchical structure,considering base station act as the root node, and the sensor nodes that areadjacent to the base station are deem to be at level and nodes in zone with hopdistance of 1 from base node are refer to be at level1 and so on, and nodeswhich are situated at the boundry are called as leaf nodes. To avoid completedepletion of Energy of a sensors node, a Zone-based Routing protocol isused. TDMA schemePacketor Task Scheduling at every nodal level is done using a Time Division MultipleAccess(TDMA) scheme.
Every level in the Routing protocol is distributed with atime slot. There is a variation of time slots. In the design of DMP schedulingvariable time slots are used because nodes at lower levels have more number ofpackets as compared to the nodes which are far from the base station.Considering the Observation, the length of time slots at upper-level nodes isset to a higher value.Fig.2: Proposed dynamic multilevelpriority (DMP) packet scheduling schemeRound-robinscheduling within the Queue-Dependingon the scheduling the DMP packet scheduling, Data packets i.e.
real-time andnon-real time data packets are scheduled among the multiple queues. Existingscheduling technique are SJF and FCFS scheduling within in queue of thesescheduling techniques of starvation free, so we propose a round robinscheduling neither round robin approach. In this approach the ready queue isperformed as circular queue.
Followingare some observations of Round robin:Bydefault it is preemptive algorithm rather than non-preemptive.Forprocessing at least once it allocates CPU to a packets in a row. PRIORITYAs we discussed before, there are two types of data packets, in which real-timedata packets and emergency data should have highest priority and non-real-timedata packets is transfer the priority depending on the sensed location and sizeof data.
The data packets that are received by node n from the lower level aregiven highest priority. however, If itis noted that the lower priority non-real timer local data cannot betransmitted due to continuous coming up of higher priority and non-real-timeremote data, they are preempted to allow low-priority data packets to bepreserve after a inescapable waiting period. FAIRNESSThismetric convince hat packets of extraneous priorities find out with a minimumwaiting time at the ready queue based on the priority of tasks or packets. Forinstance, if any lower-priority packets waits for a long period of time for thecontinuous reach of greater-priority packets, fairness defines a constraintthat permit the lower-priority packets to attain processed after a securewaiting time. Locationon sensor nodes to balance to end-to-end delay of data packets that aregenerated at different locations. Non-real time data traffic with the samepriority are processed using the shortest job first (SJF) scheduler schemesince it is very efficient in turns of average task waiting time CONCLUSIONAn energy efficient multilevel priority taskscheduler has better than FCFS, and multilevel queue scheduler in terms ofaverage task waiting time, both for real-time tasks, and all types of tasks.Using the concept of three level priority queues at each node, the proposed DMPtask scheduling scheme allow different types of data packets to be processedbase on their priorities.
Dynamic Multilevel Priority (DMP) packet schedulingscheme, its prerequisites and the factors that are being considered in thealgorithm. This paper deals with issues such as – how the starvation of bothtypes of data packets is avoided, how the processing overload, averageend-to-end delay is reduced for the delivery of both real-time andnon-real-time data packets. We studied the DMP packets scheduling scheme thatimproves the overall performance of scheduling in a WSN. REFERENCES1.
B. Pooja Priyanka, P.D. Chidambara Rao, “Dynamic multilevel priority packetscheduling scheme for wireless sensor network” in, international journals ofinnovative technologies vol.04, Issue.10, August-2016.2.
J. Nivetha, A.Deepa, “An energy efficientpacket scheduling scheme in wireless sensor networks to prevent deadlock” in,international journal of innovative research in computer and communicationengineering vol.2, Issue.11, November-2014.3. PallaviSawale, Dr.
D.J. Pete “DMP packet scheduling for wireless sensor network” in,American journal of engineering research vol.
04, Issue.01, August-2015.4. Shantveer,Dr.Jagadish S.
Kallimani,”A study on dynamic multilevel priority packetscheduling scheme for WSNs” in, international journal of latest technology inengineering, management and applied science vol.05,Issue.8, August-2016. AN ENERGY EFFICIENT MULTILEVEL PRIORITY PACKETSCHEDULING SCHEME FOR WIRELESS SENSOR NETWORK