Mac Protocol For Sensor Networks
Sensor networks try to introduce low energy consumption MAC protocols. MAC layer in the sensor nodes presents a number of module consumers of energy. Particularly, to access the channel, the IEEE 802.15.4 MAC protocol employs CSMA/CA algorithm and there is a high probability that collision and retransmission occur.
Mac Protocols For Wireless Sensor Networks Pdf
- CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): This paper proposes S-MAC, a medium-access control (MAC) protocol designed for wireless sensor networks. Wireless sensor networks use battery-operated computing and sensing devices. A network of these devices will collaborate for a common application such as environmental monitoring.
- Various medium-access control (MAC) protocols with different objectives have been proposed for wireless sensor networks. In this article, we first outline the sensor network properties that are.
- X-MAC is a low-power MAC protocol for wireless sensor networks (WSNs). In contrast to B-MAC which employs an extended preamble and preamble sampling, X-MAC uses a shortened preamble that reduces latency at each hop and improves energy consumption while retaining the advantages of low power listening, namely low power communication, simplicity and a decoupling of transmitter.
- It is a low power RTS-CTS based synchronous MAC protocol that makes use of loose synchronization between nodes to allow for duty cycling in sensor networks. In S-MAC, active period is of fixed length.
An Energy-efficient Mac Protocol For Wireless Sensor Networks Pdf
SMAC adopts a periodic wake up scheme. SMAC tries to synchronize the listen periods of neighboring nodes. The listen period of a node is divided into three phases as shown below. The listen period is the time during which a node is awake, rest of the time node is sleeping. The listen and sleep periods in the S-MAC are fixed intervals.
Three phases of listen period
In sync phase the neighboring synchronize their listen periods, a table is maintained regarding neighbors schedules, in RTS phase all nodes wishing to communicate to a particular node send RTS in CSMA mode with additional back off and in CTS the node acknowledges a particular RTS and communication between the two nodes starts and proceeds even in their sleep periods. The neighbors synchronize periodically.
SYNC packet is used to synchronize periodically. The SYNC packet contains senders address and time of its next sleep. The next sleep time is according to the sender, the receiver will adjust its timers after it receives the SYNC packet and updates the neighbor’s schedule.
In SMAC long data messages are fragmented and sent form transmitter to receiver. The receiver has to acknowledge for every fragment, else it is retransmitted. A series of fragments are sent with only one CTS and RTS message. This method is called as message passing. A protocol called T-MAC is proposed which is similar to S-MAC but with variable Listen and Sleep periods, this will help to suit the listen and sleep periods according to the load in the network.
The main concept in SMAC is that, all the neighboring nodes form virtual clusters and synchronize their sleep and listen periods. They communicate during their listen periods and sleep rest of the time. The immediate neighbors of nodes, which are transmitting and receiving, sleep until the communication is completed. A long message is divided into many fragments and all the fragments are sent as burst.
B Mac Protocol For Wireless Sensor Networks
S-MAC contributes in these ways; reduction of idle listening(as nodes sleep and not stay in idle state),collision and overhearing avoidance by using RTS and CTS, and saving energy and time, by sending a series of fragments of a long message together, rather than going for contention after sending every fragment.
Asst. Professor, Dept of E&I, Bharath University, Chennai-600073, India
|Related article atEnergy+Consumption+in+Wireless+Sensor+Network' target='_blank'>Pubmed, Energy+Consumption+in+Wireless+Sensor+Network&btnG=&hl=en&as_sdt=0%2C5' target='_blank'>Scholar Google|
An Adaptive Energy-efficient Mac Protocol For Wireless Sensor Networks
Visit for more related articles atInternational Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering
Energy efficiency is one of the major concerns in wireless sensor networks, since it impacts the network lifetime. In this paper, we investigate the relationship between sensor network performance, particularly its lifetime, and the number of active reporting nodes N by using both analytical and simulation approaches. We first demonstrate that decreasing the number of reporting nodes increases the number of reports that need to be sent to the sink in order to achieve the desired information reliability regarding a detected event. On one side, we show that reducing the number of reporting nodes reduces the probability of collision occurrence. Based on these results and as the first main contribution, we derive the optimal number of reporting nodes Nopt energy that minimizes the energy consumed to report reliably the occurrence of an event. In other words, we prove that limiting the reporting tasks of a detected event to a small subset of sensor nodes (i.e., Nopt energy), instead of using all the sensor nodes in the event area, enables significant energy conservation. Furthermore, with regard to the latency properties, we show that the average time required to reliably report an event is a convex function of the number of reporting nodes, where the minimum is obtained for a given Nopt latency Nopt energy. Consequently and as the second main contribution, we demonstrate that the fastest way to reliably report an event does not correspond to the optimal way of consuming the scarce network energy. The trade-off between these two requirements is sensor application specific, depending on this one particular need in terms of quality of service. To the best of our knowledge, we are the first to tackle the energy efficiency problem from this perspective while considering the energy-reliability-latency trade-off.
Mac Protocols For Sensor Networks Ppt
|Wireless sensor networks, energy conservation, number of reporting nodes, information reliability,performance analysis|
|Nowadays, there is a huge increase of handled devices. Laptops, mobile phones and PDAs take an important place inthe everyday life. Hence, the challenge is now to make all these devices communicate together in order to build anetwork. Obviously, this kind of networks has to be wireless. Indeed, the wireless topology allows flexibility andmobility. In this context, the idea of ad hoc networks was developed. our proposal is to limit the reporting tasks of adetected event to a small subset of sensor nodes in order to save energy consumption while respecting both latency andreliability constraints. Indeed, by reducing the number of access nodes, significant energy gain can be achieved, thanksto three enabling factors: First, such a method alleviates the energy wastage by minimizing collisions. . Second, we alsoreduce the number of redundant transmitted packets, and hence, more energy is conserved. . Finally, additional nodes(i.e., the no selected nodes to report the detected event) undergo the sleep state, which reduces the idle listening. Wenote that idle listening represents the major source of energy inefficiency, we will show how we can derive theoptimal number of reporting nodes that achieve minimal energy consumption while respecting the latency andreliability constraints. Such an algorithm runs at the sink level, and it determines dynamically, according to the currentnetwork state, the optimal setting parameters (i.e., the number of active reporting nodes N and the associated requirednumber of reports to achieve the desired reliability RðNÞ). This information concerning the number of reporting nodesto be activated is then to be broadcast to all the sensor nodes, which must be able to make use of it in order to regulatetheir access. This is typically the role of the MAC protocol. Following this philosophy, the CC-MAC protocol exploitsthe information about correlation, sent by the sink node, to select only a small subset of sensor nodes among all thepotential ones to report the detected event.|
|The aim in this case is to suppress the redundant information from being injected into the WSN. The selectionprocess is achieved based on correlation radius Rcorr, which is calculated at the sink node and indicates the averagedistance allowable between selected representative nodes. Note that in our study, a new set of reporting nodes is electedfor each event occurrence, even if the same event occurs again in the same region. As such, the reporting node rolerotates among the sensor nodes within the event area, which allows us to equalize the energy consumption throughoutthe network. The operation of the CC-MAC protocol can be described as follows: At the beginning, all the sensornodes in the event area contend for the medium access according to the basic IEEE 802.11 DCF protocol, Once asensor node accesses the medium by sending correctly a RTS frame, all the other nodes within the Rcorr radius stoptheir transmission attempt and undergo the sleep mode. Then, the remaining active nodes try again to access themedium, and the selection process is executed once more until all the representative nodes are elected.|
|As stated before, communications in current deployed WSN are usually carried using the basic IEEE 802.11 DCFprotocol and its optional RTS/CTS mechanism. Specifically, once an event is detected, the N active reporting nodescompete to access the common data channel to report the event to the sink. The IEEE 802.11 DCF access method isbased on the CSMA/CA technique. Accordingly, a host wishing to transmit a frame first senses the channel activityuntil an idle period equal to a Distributed Inter frame Space (DIFS) is detected. Then, the station waits for a randomback off interval before transmitting. The back off time counter is decremented in terms of time slots, as long as thechannel is sensed free. The counter is suspended once a transmission is detected on the channel. It resumes with the oldremaining back off interval when the channel is sensed idle again for a DIFS period. The station transmits its framewhen the back off time becomes zero. In this case, the host starts the process by sending a RTS frame. If the frame iscorrectly received, the receiving host sends a CTS frame after a Short Inter frame Space (SIFS). Once the CTS frame isreceived, the sending host transmits its data frame. If the sending host does not receive the CTS frame, a collision isassumed to have occurred. In this case, the sending host attempts to send the RTS frame again when the channel is freefor a DIFS period augmented by the new backoff.|
|A sensor node, also known as a 'mote' (chiefly in North America), is a node in a wireless sensor network that iscapable of performing some processing, gathering sensory information and communicating with other connected nodesin the network. The typical architecture of the sensor node is shown in figure.|
|Components of a Sensor Node|
|The main components of a sensor node as seen from the figure are microcontroller, transceiver, external memory,power source and one or more sensors.|
|Microcontroller performs tasks, processes data and controls the functionality of other components in the sensor node.Other alternatives that can be used as a controller are: General purpose desktop microprocessor, Digital signalprocessors, Field Programmable Gate Array and Application-specific integrated circuit. Microcontrollers are mostsuitable choice for sensor node. Each of the four choices has their own advantages and disadvantages. Microcontrollersare the best choices for embedded systems. Because of their flexibility to connect to other devices, programmable,power consumption is less, as these devices can go to sleep state and part of controller can be active. In general purposemicroprocessor the power consumption is more than the microcontroller; therefore it is not a suitable choice for sensornode. Digital Signal Processors are appropriate for broadband wireless communication. But in Wireless SensorNetworks, the wireless communication should be modest i.e., simpler, easier to process modulation and signalprocessing tasks of actual sensing of data is less complicated. Therefore the advantages of DSP’s are not that much ofimportance to wireless sensor node. Field Programmable Gate Arrays can be reprogrammed and reconfiguredaccording to requirements, but it takes time and energy. Therefore FPGA's is not advisable. Application SpecificIntegrated Circuits are specialized processors designed for a given application. ASIC's provided the functionality in theform of hardware, but microcontrollers provide it through software.|
|Sensor nodes make use of ISM band which gives free radio, huge spectrum allocation and global availability. Thevarious choices of wireless transmission media are Radio frequency, Optical communication (Laser) and Infrared.Laser requires less energy, but needs line-of-sight for communication and also sensitive to atmospheric conditions.Infrared like laser, needs no antenna but is limited in its broadcasting capacity. Radio Frequency (RF) basedcommunication is the most relevant that fits to most of the WSN applications. WSN’s use the communicationfrequencies between about 433 MHz and 2.4 GHz. The functionality of both transmitter and receiver are combined intoa single device know as transceivers are used in sensor nodes. Transceivers lack unique identifier. The operationalstates are Transmit, Receive, Idle and Sleep.|
|Current generation radios have a built-in state machines that perform this operation automatically. Radios used intransceivers operate in four different modes: Transmit, Receive, Idle, and Sleep. Radios operating in Idle mode resultsin power consumption, almost equal to power consumed in Receive mode. Thus it is better to completely shutdown theradios rather than in the Idle mode when it is not Transmitting or Receiving. And also significant amount of power isconsumed when switching from Sleep mode to Transmit mode to transmit a packet.External Memory|
|From an energy perspective, the most relevant kinds of memory are on-chip memory of a microcontroller andFLASH memory - off-chip RAM is rarely if ever used. Flash memories are used due to its cost and storage capacity.Memory requirements are very much application dependent. Two categories of memory based on the purpose ofstorage a) User memory used for storing application related or personal data. b) Program memory used forprogramming the device. This memory also contains identification data of the device if any.|
|Power consumption in the sensor node is for the Sensing, Communication and Data Processing. More energy isrequired for data communication in sensor node. Energy expenditure is less for sensing and data processing. Theenergy cost of transmitting 1 Kb a distance of 100 m is approximately the same as that for the executing 3 millioninstructions by 100 million instructions per second/W processor. Power is stored either in Batteries or Capacitors.Batteries are the main source of power supply for sensor nodes. Namely two types of batteries used are chargeable andnon-rechargeable. They are also classified according to electrochemical material used for electrode such asNiCd(nickel-cadmium), NiZn(nickel-zinc), Nimh (nickel metal hydride), and Lithium-Ion. Current sensors aredeveloped which are able to renew their energy from solar, thermo generator, or vibration energy. Two major powersaving policies used are Dynamic Power Management (DPM) and Dynamic Voltage Scaling. DPM takes care ofshutting down parts of sensor node which are not currently used or active. DVS scheme varies the power levelsdepending on the non-deterministic workload. By varying the voltage along with the frequency, it is possible to obtainquadratic reduction in power consumption.|
|Sensors are hardware devices that produce measurable response to a change in a physical condition like temperatureand pressure. Sensors sense or measure physical data of the area to be monitored. The continual analog signal sensedby the sensors is digitized by an Analog-to-digital converter and sent to controllers for further processing.Characteristics and requirements of Sensor node should be small size, consume extremely low energy, operate in highvolumetric densities, are autonomous and operate unattended, and be adaptive to the environment. As wireless sensornodes are micro-electronic sensor device, can only be equipped with a limited power source of less than 0.5 Ah and 1.2V. Sensors are classified into three categories.|
|• Passive, Omni Directional Sensors: Passive sensors sense the data without actually manipulating theenvironment by active probing. They are self powered i.e energy is needed only to amplify their analog signal. There isno notion of “direction” involved in these measurements.|
|• Passive, narrow-beam sensors: These sensors are passive but they have well-defined notion of direction ofmeasurement. Typical example is ‘camera’.|
|• Active Sensors: This group of sensors actively probes the environment, for example, a sonar or radar sensor orsome type of seismic sensor, which generate shock waves by small explosions.|
|The overall theoretical work on WSN’s considers Passive, Omni directional sensors. Each sensor node has a certainarea of coverage for which it can reliably and accurately report the particular quantity that it is observing. Severalsources of power consumption in sensors are a) Signal sampling and conversion of physical signals to electrical ones,b) signal conditioning, and c) analog-to-digital conversion. Spatial density of sensor nodes in the field may be as highas 20 nodes/ m3.|
|Sensor nodes in order to save energy consumption while respecting both latency and reliability constraints. Indeed,by reducing the number of access nodes, significant energy gain can be achieved, thanks to three enabling factors: First,such a method alleviates the energy wastage by minimizing collisions. . Second, we also reduce the number ofredundant transmitted packets, and hence, more energy is conserved. . Finally, additional nodes (i.e., the non selectednodes to report the detected event) undergo the sleep state, which reduces the idle listening. We note that idle listeningrepresents the major source of energy inefficiency; we will show how we can derive the optimal number of reportingnodes that achieve minimal energy consumption while respecting the latency and reliability constraints. Such analgorithm runs at the sink level, and it determines dynamically, according to the current network state, the optimalsetting parameters (i.e., the number of active reporting nodes N and the associated required number of reports toachieve the desired reliability RðNÞ).|
|This information concerning the number of reporting nodes to be activated is then to be broadcast to all the sensornodes, which must be able to make use of it in order to regulate their access. This is typically the role of the MACprotocol. Following this philosophy, the CC-MAC protocol exploits the information about correlation, sent by the sinknode, to select only a small subset of sensor nodes among all the potential ones to report the detected event.|
|The aim in this case is to suppress the redundant information from being injected into the WSN. The selectionprocess is achieved based on correlation radius Rcorr, which is calculated at the sink node and indicates the averagedistance allowable between selected representative nodes. Note that in our study, a new set of reporting nodes is electedfor each event occurrence, even if the same event occurs again in the same region. As such, the reporting node role rotates among the sensor nodes within the event area, which allows us to equalize the energy consumption throughoutthe network.The operation of the CC-MAC protocol can be described as follows: At the beginning, all the sensor nodesin the event area contend for the medium access according to the basic IEEE 802.11 DCF protocol,Once a sensor nodeaccesses the medium by sending correctly a RTS frame, all the other nodes within the Rcorr radius stop theirtransmission attempt and undergo the sleep mode. Then, the remaining active nodes try again to access the medium,and the selection process is executed once more until all the representative nodes are elected.|
|As stated before, communications in current deployed WSN are usually carried using the basic IEEE 802.11 DCFprotocol and its optional RTS/CTS mechanism. Specifically, once an event is detected, the N active reporting nodescompete to access the common data channel to report the event to the sink.|
|The IEEE 802.11 DCF access method is based on the CSMA/CA technique. Accordingly, a host wishing to transmita frame first senses the channel activity until an idle period equal to a Distributed Inter frame Space (DIFS) is detected.Then, the station waits for a random backoff interval before transmitting. The backoff time counter is decremented interms of time slots, as long as the channel is sensed free. The counter is suspended once a transmission is detected onthe channel. It resumes with the old remaining backoff interval when the channel is sensed idle again for a DIFS period.The station transmits its frame when the backoff time becomes zero. In this case, the host starts the process by sendinga RTS frame. If the frame is correctly received, the receiving host sends a CTS frame after a Short Inter frame Space(SIFS). Once the CTS frame is received, the sending host transmits its data frame. If the sending host does not receivethe CTS frame, a collision is assumed to have occurred. In this case, the sending host attempts to send the RTS frameagain when the channel is free for a DIFS period augmented by the new backoff, Successful transmission from the firstattempt. We propose the spatial Correlation-based Collaborative MAC (CC-MAC) protocol that aims tocollaboratively regulate sensor node transmissions. It follows from our earlier discussion in Section III that thedistortion constraint can be achieved even though the number of nodes sending information about an event isdecreased. Furthermore, by intelligently selecting the locations of representative nodes, the distortion DE(M) can befurther reduced.|
|In order resides at the sink, determines the correlation radius, rcorr for a distortion constraint, Dmax, as explained inSection IV. This information is then broadcast to each sensor node during the network setup. The CC-MAC protocol,which is implemented at each sensor node, then performs MAC distributively. CC-MAC exploits spatial correlation inthe MAC layer by using the correlation radius, rcorr, to suppress the redundant information from being injected into theWSN. We now present the principles of CC-MAC protocol in detail. When a specific source node, ni, transmits itsevent record to the sink, all of its correlation neighbors have redundant information with respect to the distortionconstraint, Dmax. This redundant information, if sent, increases the overall latency and contention within thecorrelation region, as well as wasting scarce WSN energy resources. Our proposed spatial Correlation-basedCollaborative MAC (CC-MAC) protocol aims to prevent the transmission of such redundant information and inaddition, prioritize the forwarding of filtered data to the sink. In WSN, the sensor nodes have the dual functionality ofbeing both data originators and data routers. Hence, the medium access is performed for two reasons:|
|• Source Function: Source nodes with event information perform medium access in order to transmit their packets tothe sink.|
|• Router Function: Sensor nodes perform medium access in order to forward the packets received from other nodesto the next destination in the multi-hop path to the sink.|
|In order to address these two different contention attempts in WSN, our spatial Correlation-based CollaborativeMAC (CCMAC) protocol contains two components corresponding to the source and router functionalities. Event MAC(E-MAC), filters out the correlated records and Network MAC (N-MAC) ensures prioritization of route-thru packets.More specifically, a node performs E-MAC when it wants to transmit its sensor reading to the sink, while N-MAC isperformed when a node receives a packet and tries to forward it to the next hop. A typical WSN with the E-MAC andN-MAC application areas are shown in|
|Since centralized medium access is not preferred in WSN, we use a distributed protocol to determine therepresentative nodes. Both E-MAC and N-MAC use a CSMA/CA based medium access control with appropriatemodifications and enhancements. The information about correlation formation is embedded inside theRTS/CTS/DATA/ACK packets. Each node is informed about the correlation information about a node using thesepackets. As a result, additional signalling is not required for our CC-MAC protocol. We explain the packet structureand the principles of both E-MAC and N-MAC in the following sub-sections.|
|A.Event MAC (E-MAC)|
|The Event MAC (E-MAC) protocol aims to filter out correlated event information by forming correlation regionsbased on the correlation radius, rcorr, in each correlation region; a single representative sensor node transmits data for aspecific duration, while all other nodes stop their transmission attempts. After each transmission duration a newrepresentative node is selected as a result of the contention protocol. All sensor nodes contend for the medium for thefirst time so that the representative nodes are selected by the help of the spatialreuse property of the wireless channel.This initial phase is called as the first contention phase and is explained as follows.|
|B.Network MAC (N-MAC)|
|As a node records an event and transmits its packets using E-MAC, these packets are forwarded through thenetwork by intermediate nodes which perform the router functionality. In addition, node deployment over large sensorfields may have to deal with multiple concurrent events. Hence, when a packet is routed to the sink, it may traversethrough nodes corresponding to other concurrent events. However, since the correlation has already been filtered outusing E-MAC, the route-thru packet must be given priority over the packets generated by another concurrent event.This is the reason why we need a Network MAC (N-MAC) component. When an intermediate node receives a DATApacket, it performs N-MAC to further forward that packet to the next hop. The route-thru packet is given precedence intwo phases. When a correlation neighbor receives an RTS regarding a route-thru packet during the random listeningperiod of the SSS, it switches from SSS to receive state and receives the packet. During the transmission, therepresentative node defers its transmission and the route-thru packet is received by the correlation neighbor. In order tofurther exploit the higher priority of the routethru packet, we use a priority scheme similar to that in IEEE 802.11 PointCoordinate Function (PCF).|
|A node in a correlation region with a route-thru packet listens to the channel for PCF Inter Frame Space (PIFS) timeunits, which is smaller than the DCF Inter Frame Space (DIFS) used by the nodes performing E-MAC. The routernode, then, sets its backoff window size to a random number which is between [0, CWmax − 1], where CW max is avalue smaller than the actual CWmax used by the representative node. Such a principle increases the probability thatthe router node captures the channel since the router node begins backoff before the representative node of thecorrelation region. As a result, the route-thru packet is given precedence. Since backoff procedure is still used, thecollision between multiple route-thru packets that may be in the same correlation region is prevented. If, on the otherhand, the representative node receives the routethru packet, it simply gives precedence to the route-thru packet over itsgenerated packet and forwards the route-thru packet.|
|C. AOMDV Protocol|
|When a source has data to transmit to an unknown destination,it broadcasts a Route Request (RREQ) for thatdestination . At each intermediate node, when a RREQ is received a route to the source is created. If the receiving nodehas not received this RREQ before, is not the destination and does not have a current route to the destination, itrebroadcasts the RREQ. If the receiving node is the destination or has a current route to the destination, it generates aRoute Reply (RREP). The RREP is unicast in a hop-byhop fashion to the source. As the RREP propagates, eachintermediate node creates a route to the destination. When the source receives the RREP, it records the route to thedestination and can begin sending data. If multiple RREPs are received by the source, the route with the shortest hopcount is chosen. As data _ows from the source to the destination, each node along the route updates the timersassociated with the routes to the source and destination, maintaining the routes in the routing table.|
|Figure AOMDV in NS2|
|Network simulator 2 is used as the simulation tool in this project. NS was chosen as the simulator partly because ofthe range of features it provides and partly because it has an open source code that can be modified and extended. Thereare different versions of NS and the latest version is ns-2.1b9a while ns-2.1b10 is under development.|
|Network Imulator (Ns)|
|Network simulator (NS) is an object–oriented, discrete event simulator for networking research. NS providessubstantial support for simulation of TCP, routing and multicast protocols over wired and wireless networks. Thesimulator is a result of an ongoing effort of research and developed. Even though there is a considerable confidence inNS, it is not a polished product yet and bugs are being discovered and corrected continuously.|
|NS is written in C++, with an OTcl1 interpreter as a command and configuration interface. The C++ part, which isfast to run but slower to change, is used for detailed protocol implementation. The OTcl part, on the other hand, whichruns much slower but can be changed very quickly, is used for simulation configuration. One of the advantages of thissplit-language program approach is that it allows for fast generation of large scenarios. To simply use the simulator, itis sufficient to know OTcl. On the other hand, one disadvantage is that modifying and extending the simulator requiresprogramming and debugging in both languages.|
|NS can simulate the following:|
|1.Topology: Wired, wireless|
|2. Sheduling Algorithms: RED, Drop Tail,|
|3. Transport Protocols: TCP, UDP|
|4. Routing: Static and dynamic routing|
|5. Application: FTP, Telnet, Traffic generators.|
|The spatial Correlation-based Collaborative MAC (CCMAC) protocol proposed in this work is designed fordistributed implementation and has two components: Event MAC (E-MAC) that filters out the correlation in sourcerecords and Network MAC (N-MAC) that prioritizes the transmission of route-thru packets over other packets. Routethrupackets are representative of an entire correlation region and hence given higher priority on their way to the sink.Using simulations, the performance of the CC-MAC protocol is investigated and significant performance gains in termsof energy consumption, latency and packet drop rate are shown. Our work shows that, by exploiting spatial correlation,the transmission of redundant nodes can be controlled. Moreover, controlling the transmission of sensor nodes has alsobeen investigated in the application layer in terms of topology control these protocols focus on connectivity of thenetwork and the traffic properties of the generated traffic, CC-MAC provides a localized control based on the spatialcorrelation in the physical phenomenon.|