Reliable Energy Efficient Video Routing in Wireless Multimedia Sensor Networks - SEMINAR

 

1. Introduction

 

 

            Wireless sensor networks (WSNs) typically consist of a large number of intelligent battery-powered sensor nodes with sensing, processing and wireless communicating capabilities [1]. The sensingcircuitry measures simple ambient conditions, related to the environment surrounding the sensor such as temperature, humidity or light, and transform them into an electric signal. Processing such a signalreveals some properties about objects located and/or events happening in the vicinity of the sensor.

 

            The above mentioned characteristics impose a lot of restrictions on the WSNs design such as faulttolerance, scalability, productioncosts, network topology, operating environment, hardware constraints,power consumption, etc. These challenges have led to an intensive research in the past few years that addresses the potential collaboration among sensors in data gathering and processing. In mostapplications, the deployment area has no existing infrastructure for either energy or communication.Therefore, a basic requirement for sensor nodes is to be able to survive with a limited source of energywhich is usually a small battery.

 

            The network should stay alive and active for a duration of timethat depends on the application of the deployed network, and that may last from several weeks to afew years.Nevertheless, the rapid development and progress of sensors, MEMS, embedded computing, inaddition to the availability of inexpensive CMOS (Complementary Metal Oxide Semiconductor) cameras and microphones coupled with the significant progress in distributed signal processing and multimediasource coding techniques, allowed for the emergence of so called wireless multimedia sensor networks

 

2. Literature Survey

 

 

Jamal N. Al- Karaki, Ahmed E.Kamal “Routing techniques in wireless sensor networks: A survey”

 

            We use a classification according to the network structure and protocol operation (routing criteria)[2]. The classification is shown in Figure 1

 

 

Fig 1: Routing protocols in wsn: A taxonomy

 

a) Network Structure Based Protocols

            The underlying network structure can play significant role in the operation of the routing protocol in WSNs. In this section, we survey in details most of the protocols that fall below this category.

 

Ø  Flat Routing

            The first category of routing protocols is the multihop flat routing protocols. In flat networks, each node typically plays the same role and sensor nodes collaborate together to perform the sensing task. Due to the large number of such nodes, it is not feasible to assign a global identifier to each node. This consideration has led to data centric routing, where the BS sends queries to certain regions and waits for data from the sensors located in the selected regions. Since data is being requested through queries, attribute-based naming is necessary to specify the properties of data.

            Early works on data centric routing, e.g., SPIN and directed diffusion were shown to save energy through data negotiation and elimination of redundant data. These two protocols motivated the design of many other protocols which follow a similar concept.

 

Ø  Hierarchical Routing

            Hierarchical or cluster-based routing, originally proposed in wireline networks, are well-known techniques with special advantages related to scalability and efficient communication. As such, the concept of hierarchical routing is also utilized to perform energy efficient routing in WSNs. In a hierarchical architecture, higher energy nodes can be used to process and send the information while low energy nodes can be used to perform the sensing in the proximity of the target. This means that creation of clusters and assigning special tasks to cluster heads can greatly contribute to overall system scalability, lifetime, and energy efficiency. Hierarchical routing is an efficient way to lower energy consumption within a cluster and by performing data aggregation and fusion in order to decrease the number of transmitted messages to the BS. Hierarchical routing is mainly two-layer routing where one layer is used to select clusterheads and the other layer is used for routing. However, most techniques in this category are not about routing, rather on "who and when to send or process/aggregate" the information, channel allocation etc., which can be orthogonal to the multihop routing function.

 

Ø  Location based routing protocols

            In this kind of routing, sensor nodes are addressed by means of their locations. The distance between neighbouring nodes can be estimated on the basis of incoming signal strengths. Relative coordinates of neighboring nodes can be obtained by exchanging such information between neighbors. Alternatively, the location of nodes may be available directly by communicating with a satellite, using GPS (Global Positioning System), if nodes are equipped with a small low power GPS receiver. To save energy, some location based schemes demand that nodes should go to sleep if there is no activity. More energy savings can be obtained by having as many sleeping nodes in the network as possible.

            Mariam AlNuaimi, FaragSallabi, KhaledShuaib “A survey of wireless multimedia sensor networks”

 

            Wireless Sensor Networks (WSNs) have been the focus of many researchers during the last decade due to the advances in low power and low cost hardware (i.e., micro-electromechanical systems (MEMS). A wireless sensor network consists of wirelessly interconnected devices that can interact with each other and with their surrounded environment by controlling and sensing physical parameters

 

            During the last few years, Wireless Multimedia Sensor Networks (WMSNs) appeared [3]. WMSNs technology have emerged due to the production of cheap CMOS(Complementary Metal Oxide Semiconductor) cameras and microphones, which can acquire rich media content from the environment like images and videos.

WMSN can be defined as networks of wirelessly interconnected sensor nodes equipped with multimedia devices, such as cameras that are capable of retrieving video and audio streams, images, and scalar sensor data. WMSNs are currently being used in several applications as outlined below.

 

A. Multimedia surveillance sensor networks

            Multimedia surveillance applications are used to detect, recognize and track the objects in order to take appropriate actions. These applications need to continuously capture images in order to monitor certain events. These applications are mainly used for detecting crimes or terrorist attacks.

 

B. Traffic avoidance and control systems

            Traffic avoidance applications are used to monitor car traffic and provide traffic routing advice to avoid congestion. M. Jokelaproposed a model of three different kinds of cameras to be used in monitoring a traffic situation around a vehicle to detect problems such as a near infrared camera, a thermal imaging system for animal detection, and a regular CCTV camera for ice and snow detection.

C. Advanced health care delivery

            Health and care delivery applications are used for patient monitoring and care in remote sites like monitoring patients’ facial expression, respiratory conditions or movement andforward these images to doctors in distant hospitals to make better diagnosis. In a healthcare sensor periodically captures vital signs information (e.g., body temperature, Blood pressure) and sends it to the gateway. Once the information processed by the gateway, it is forwarded to doctors to helpthem make an initial diagnosis. After that, wireless multimedia sensor nodes used to capture and send back images or videos data to help doctors obtain more detailed information and make final diagnosis.

 

D. Automated parking advice

            Automated parking advice applications keep track of available parking spaces and provide guidance to the drivers to allocate free parking spaces.

 

Wireless Multimedia Sensor Networks challenges and resource constraints:

            In this section we discuss some of the unique requirements and challenges for WMSNs application such as high bandwidth demand, multimedia coding techniques, and application-specific QoS requirements.

 

A. Multimedia Coding Techniques

            Multimedia processing and source coding has been used to handle multimedia content over wireless sensor networks and to support real time multimedia applications.

 

            These coding techniques should be designed in such a way that they meet current resource capabilities such as memory, data rate,battery, processing power and bandwidth. Thus, Multimedia coding techniques should be used to decrease the amount of multimedia content transferred over the network by extracting the useful information from the captured images and video streams while keeping the application-specific QoS requirements.

B. Application-specific QoS requirements

            A WMSNs application has different requirements from the usual scalar sensor applications. In addition to data delivery required by scalar sensor networks, multimedia data include images and streaming multimedia content. Images are multimedia data obtained in a short time period.

 

            However, streaming multimedia content is generated over longer timeperiods and requires continuous data capturing and delivery. As a result, better hardware and coding and compression algorithms are needed in order to deliver QoS required by specific applications.

 

C. Resource Constraints

            Multimedia sensors differ from the scalar sensor devices in terms of the type of data they are capturing. Video, images and audio data require more resources such as battery, memory, processing capability, and achievable data rates.

 

            Amir HosseinMohajerzadeh, Mohammad HosseinYaghmaee, Reza Monsefi “A qos based data dissemination protocol for wireless multimedia sensor networks”

 

Protocol Features In Wireless multimedia sensor networks:

Ø  Energy consumption efficiency: like wireless sensor networks nodes, nodes which are designed for wireless multimedia sensor networks also have limited primary energy resources and they mostly can't be recharged so energy consumption is still mentioned as a basic parameter.

 

Ø  Self-configuration: usually there is no way to monitor wireless sensor networks nodes, so nodes should be designed in a way that they have the ability to continue their function without user interference.

 

Ø  Capability of sending data with different real time requirements: for different reasons traffics with different priorities are forwarded in wirelessmultimedia sensor networks. Protocols should havethe ability to send the traffics simultaneously and asa result each traffic receives its own real timerequirements.

 

Ø  The ability of sending data with different reliabilities: wireless multimedia sensor networks traffics need different reliabilities. These networks protocolsshould have the ability of sending these traffics.

 

3. Problem Statement

 

 

            For a given wireless multimedia sensor network, including the source node and one sink node as destination. Due to communication capacity limitation, most of the nodes need to send their data by multipath method to sink node. We aim to design a routing protocol that can guarantee the reliability of data transmission and balance the energy consumption while delivering data from all source nodes to the sink node

 

 

4. Proposed Methodologies

 

4.1            Reliable Routing In Wireless Multimedia Sensor Networks Based On Energy Prediction:

            The reliable routing based on energy prediction(REP), includes energy prediction and power allocationmechanism [4]. The introduced prediction mechanism makes thesensor nodes predict the remaining energy of other nodes [5], whichdramatically reduces the overall information needed for balancing energy.

 

4.1.1 Multimedia Location Aided Flooding (MLAF):

            MLAF considers network as a virtual grid. Network nodes are aware of their own geographical position.Before MLAF protocol is designed for data dissemination in wireless multimedia sensor networks. To send sink node'sdata to all of network nodes is the main aim of datapropagation algorithms.

 

MLAF protocol follows 3 main goals:

1.      Sending data to all of network nodes using proper energy consumption.

2.      Sending data with different delays based on itspriorities.

3.      Considering different reliabilities for data with different priorities.

 

            In figure 2, we can see structure of a grid cell and its 4 neighbors. Each grid cell has 2, 3 or 4 neighbors.

Fig 2: A Grid Cell

 

A. Directional Forwarding

            As you see in figure, the 4 neighbors of a grid cell are identified with E, N, S and W. normally data enter the cell from 4 directions. In data propagation as done in LAF, packets with redundant data enter the cell from 4 directions. In MLAF protocol, we can consider traffics with differentpriorities. Two priorities are needed:

 

1.      For low priority data, each grid cell should receive data only from the southern(S) cell and other data entering from other side cells should be destroyed.It happens when sink node is one of the southernnodes of network.

2.      For high priority data, each grid cell receives data from all its neighbor cells.

 

            Considering two rules above, network is capable of sendingtwo types of data: low priority traffic and high priority traffic. Facing packet loss, Low priority traffic has less sensitiveness rather than that of high priority traffic. In otherwords, low priority traffic has a more flexible packet loss threshold in comparison to high priority traffics. MLAF sends data with high priority using method 2 and the ones with low priority using method 1.

 

B. Delay Sensitive Forwarding:

            Delay in wireless multimedia sensor networks depends on the number of hops. Generally, in computer networks, delayparameter is consists of two parts; link propagation delay andintermediate nodes delay. Link propagation delay is the timespent on sending packet from one node to its neighbor node.Intermediate node delay is the time that one packet spends ineach of intermediate nodes.

 

            In MLAF, different traffics with different threshold delay can be sent; So Two priorities are considered for traffics, high priority and low priority. Packet with high prioritybelongs to the traffic which needs less delay comparing to low priority traffic. To send high priority packets, MLAF reduces the number of hops between receiver and transmitter by reducing the number ofintermediate nodes.

 

 

4.1.2 Multimedia Reliable Energy Efficient Routing Protocol(MREEP):

            MREEP is a data centric routing protocol which considers end to end delay, reliability, energy consumption, lifetime and fairness have been taken into account. MREEP (Multimedia Reliable Energy Efficient routing Protocol) [7] provides sending traffics with different priorities and QoS requirements based on constraint based routing.

 

            MREEP is a data centric protocol which is composed of the following 4 different phases: request dissemination, event occurrence report, route establishment and data forwarding.The proposed protocol structure is shown in Fig.3.

 

 

Fig 3. Protocol structure

 

A. Data Dissemination Phase:

            Across MREEP phases this phase is done first. In this phase sink sends its desirable requests to the entire network nodes. In other words, sink requests are propagated through entire networks using a data dissemination algorithm. The mentioned data dissemination algorithm is very significant here. In many applications one request should be sent to all nodes (broadcast), but in other applications request will be sent to nodes based on their position (multicast).

 

            This phase is begun by the sink. All the packets which areused in this phase have the same format. The proposed protocol MREEP uses the MLAF [4] protocol to perform this phase.

 

B. Event Occurrence Report Phase:

            In this phase the relevant information to the occurred event will be sent to the sink but sending of the fundamentalinformation relevant to the event will be done in the datasending phase. Furthermore the very phase paves the way forproviding packet routing. With this end in mind a packet willbe created by a node and the relevant data to the sensed eventwill be located there. Through sending the packet to the sinkthe necessary routing tables will be provided for the aim of data routing in the nodes.

 

            The final routing will be executed in theroute establishment phase. Indeed in the second phase in each node the completion of the final routing will be done bygathering all the essential information in each node in the form of permanent routing table. This act will end in the creation ofrouting tables for each specific node in the third phase.

 

            In the figure 4 part<a> the pseudo code of the second phase for the event sensor node and in part <b>pseudo code in thesecond phase for other nodes (the packet transmitting packet).

 

 

<a>

/* Phase 2 pseudo code for sensor node */

/* when a node sense an event */

If( is this event relevant to node’s task )

Then continue;

Else ignore event;

Collect necessary information as determined in request packets;

Send packet to all node’s neighbors;

 

<b>

/* Phase 2 pseudo code for relay nodes */

/* the node got packet from its neighbor */

If ( the node is closer to sink than sender node )

Then continue;

Else ignore packet;

If ( the packet is not repetitive )

Then create a record for it in proposed routing table;

Else ignore packet;

Send packet to all nodes neighbors

 

 

Fig 4. Pseudo code for event occurrence report phase.

 

C. Route Establishment Phase:

            After the sink received all the second phase packets, it sends back and acknowledge packet (this packet is called thethird packet phase) to the source node announcing to send allits gathered data to the sink. It is possible for an event to besensed by more than a sensor node. At this stage according tothe sent data by the source node, the sink chooses one or morenodes for the final data sending. In the second phase packet,each packet specifies its own sensing accuracy.  After choosing the source node, the thirdphase packet will be sent to its destination.

 

            As the third phase packet traverses the path, it creates the third phase table in the middle nodes. The third phase routingtable is the final routing table which made the sent data routingpossible from the source node. The sending acknowledgement depends on the sensed event priority. Two differentacknowledgements are considered, acknowledgement for highpriority (real time traffic) and acknowledgement for lowpriority (non- real time traffic).

 

Figure 5, shows the pseudo code for route establishment phase.

 

 

/* sink receives packet type 2 */

Sink determines packet information type;

If (packet information is high priority )

Then do high priority module;

Else do low priority module;

<a>

/* high priority module */

Find packet source;

Look up proposed routing table for determined source;

Select first relevant row;

Add a record for selected source in RT-routing-table;

Send packet type 3 to node which is declared in selected row;

 

<b>

/* low priority module */

Find packet source;

Look up proposed routing table for determined source;

/* for each record, variable X is calculated as (path length/hop count) */

Select two records with highest value X;

Add a record for source, based on each selected record in NRT-routing-table;

Send packet type 3 to nodes which are declared in two selected records

 

 

Fig 5. Pseudo Code for Route Establishment Phase.

 

 

 

 

 

D. The data forwarding phase

            At the end of the third phase the real time and non-real time routing table will be created. Each node owns a real time andnon-real time third phase routing table.

 

            The source node (the event sensor node) depending on thetype of event sensed can send its data to the sink once it hasreceived real time acknowledgement (the real time third phasepacket) and non-real time acknowledgement (the non-real timeacknowledgement).

 

 

 

4.1.3 Minimum Hop Disjoint Multipath Routing Algorithm(MHDM):

            MHDM aim to construct the fully disjoint multipath [6] from source to sink with least time delay andenergy consuming. It should be simple which cause leastcomputation in inner sensor nodes. The sensors only havelocal knowledge of neighbor nodes and their hop counts, no global topology and geography information required.

 

            The algorithm [8] is divided into two phases, the first phaseis built up the path, and the second is path acknowledgment. We consider multiple sources need to construct paths to sink and will have joint nodes between different sources. Threepaths will be built up for each source. The first one is theprimary path, second one is the alternate path and the third one is the backup path. Backup path by default is not used at start only with path failure of either primary or alternatepath will trigger using backup path for data transmit.

 

A. Phase 1: Path build-up

1) Step 1: When a video sensor (source) [10] be activated, it will send out the path build request package to the neighborswhich hop count is smaller than the source. The neighborsreceive the request package and add node number of itself into the package, also add the timestamp of this node, then send out to its smaller hop count neighbors. This package which contain the route node number and transmit from high hop count to low will finally reach to the sink. The first package reaches the sink which with least time delay contains the primary path information. So the primary path is build up.

 

2) Step 2: After the first package reach the sink, there still have other packages come from different routes to thesink. When a new package arrives, extract the route andcompare to the primary path. The compare is simple. If thereis joint node, then discard the package. If not, the alternatepath is found. Continue to receive package and compare with both primary and alternate path to find the backup path. If after a timeout the backup path is not found, then give up onbackup path. At last, paths are found.

B. Phase 2: Path acknowledgement

Step 3: After paths build up, sink should send back acknowledgment message (ACK) back to the sources.

 

5. Conclusion

 

 

 

            As a resource constrained network, wireless multimedia sensor network should try to reduce the unnecessary energyconsumption. We study the optimization of balancing energy consumption with reliable data transmission. Then we propose a reliable routing based on energy prediction for WMSN [9]. Power allocation and energy prediction mechanism are both adopted in REP, which can be used to realize energy balance under the condition of ensuring the reliabletransmission.

 

 

REFERENCES

 

 

[1]        I.F.Akyildiz, W. su, Y. sankarasubramaniam “A survey of wireless sensor networks”, IEEE wireless communication 2010

 

[2]        Jamal N. Al- Karaki, Ahmed E.Kamal “Routing techniques in wireless sensor networks: A survey”

 

[3]        Mariam AlNuaimi, Farag Sallabi, Khaled Shuaib “A survey of wireless multimedia sensor networks”, IEEE wireless communication, 2011

 

[4]        Amir Hossein Mohajerzadeh, Mohammad Hossein Yaghmaee, Reza Monsefi “A qos based data dissemination protocol for wireless multimedia sensor networks”, IEEE transactions on computers, 2010

 

[5]        Ye Ming Lu, Vincent W.S.Wong “An energy efficient multipath routing protocol for wireless sensor networks”

 

[6]        Shobha Poojary, Manohar Pai M M “Multipath data transfer in wireless multimedia sensor networks” IEEE 2010

 

[7]        Amir Hossein Mohajerzadeh, Mohammed Hossein Yaghmaee, Najmeh Najmi Toroghi “MREEP:A qos based routing protocol for wireless multimedia sensor networks” IEEE 2011

 

[8]        Kai Lin, Min Chen “Reliable routing based on energy prediction for wireless multimedia sensor networks” IEEE org,2010

 

[9]        Guannan Sun, Jiandong Qi, Zhe Zang “A reliable multipath routing algorithm with related congestion control scheme in wireless multimedia sensor networks” IEEE 2011

[10]      Elham Karimi, Behzad Akbari “Improving video delivery over wireless multimedia sensor networks based on queue priority scheduling” IEEE 2011

 

[11]      Bastien Mainand, Mariem Zekri “Improving routing reliability on wireless sensor networks” IEEE 2008.