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EC8702-ADHOC AND WIRELESS SENSOR NETWORKS-UNIT NOTES.pdf
- 1. EC8702 Ad Hoc and Wireless Sensor Networks UNIT-I AD HOC NETWORKS – INTRODUCTION AND ROUTING PROTOCOLS www.rejinpaul.com
- 2. Computer Network A set of independent computers connected together for exchanging data and other resources Interlinked by physical media such as copper cable, fiber optic and wireless radio waves www.rejinpaul.com
- 3. Wireless communication • Information can be transmitted through air without requiring any cables or wires www.rejinpaul.com
- 4. • Topics to be covered: 1. Fundamentals of Wireless communication 2. Electromagnetic Spectrum i. Types ii. Frequency Bands iii. Spectrum allocation methods 3. Radio Propagation mechanisms i. Reflection ii. Diffraction iii. Scattering 4. Characteristics of Wireless channel. 5. Mobile Adhoc Networks (MANET) 6. Wireless Sensor Networks (WSN) www.rejinpaul.com
- 5. 1. Fundamentals • Users can communicate from remote areas • Information can be communicated without wires, cables or any electrical conductors • Examples of wireless devices are Cordless telephones Mobiles GPS units Satellite television Wireless computer parts www.rejinpaul.com
- 6. Wireless devices Cordless telephones Mobiles GPS units Satellite television Wireless computer parts www.rejinpaul.com
- 8. Difference between wired and wireless communication • Wired N/W Ethernet cable • Wireless n/w Infrared / radio frequency signals www.rejinpaul.com
- 11. Advantages • Self configuring • Easy to use • Communication has enhanced due to convey the information very quickly • Military areas, flooded areas, hazardous area etc.. • Medical applications… www.rejinpaul.com
- 14. Disadvantages More attack by unauthorized users Requires strong security protocols. Disturbed by abnormal climate, noise interference etc.. Limited bandwidth Stability of network is less Speed is slower Coverage problem etc www.rejinpaul.com
- 15. Types of wireless communication • Infrared wireless communication • Cellular systems • Cordless phones • WLANs • Satellite communication • Bluetooth technology • Zigbeee • WiMax www.rejinpaul.com
- 16. Infrared wireless communication • Infrared waves are used • Short to medium range communication Features: Line of sight communication Intrusion detectors Motion detectors Home entertainment control units Medical diagnostic devices Headsets, modems, printers etc.. www.rejinpaul.com
- 17. Cellular systems • 1960 - Analog communication •Provide voice and data communication Working Coverage area is divided into non-overlapping cells – mobile devices Fixed point base station Mobile switching center – allocating channels www.rejinpaul.com
- 18. Various levels… • 1G- Advanced Mobile Phone Services (FDMA+ 30KHz FM modulated voice channel) • 2G – Global System for Mobile communication (100kbps) • 3G- different data rate depends on the mobility and location www.rejinpaul.com
- 19. Cordless phones • 1970s - initiated • Low cost and short wireless link • Radio waves with specific frequency • Specific distance from base station • It uses Base station and handset • BS call as Electrical signal– radio signal– handset of the user • Radio signal – electrical signal – speaker - sound form • Base station & handset --- > frequency pair www.rejinpaul.com
- 20. Wireless LAN • It link more wireless devices by wireless distribution method • Limited area – home, school computer lab, office building etc.. • IEEE 802.11 standard – high frequency radio waves • WLAN – LAWN • WLAN – AP – internet www.rejinpaul.com
- 21. Cond…. • AP- transmits and receives the radio frequency signals - routers • AP -- client • Clients – several devices…. • CSMA/CA for path sharing also include encryption method -- security www.rejinpaul.com
- 22. Satellite communication • It connect any where on the earth • It rotate around the earth for gathering and transmitting useful information Working Principle • Satellite (sensors) earthstation • Earth station – GHz signals Satellite • Satellite – signal to earth (all stations with in coverage area) • Tracking and command system – uplink and down link • Bigger in size, consumes more power and more expensive www.rejinpaul.com
- 23. Bluetooth technology • Short distance commn. using short wavelength • IEEE 802.15.1 • Uses ultra high frequency radio waves • Connecting two point to point devices • It transmits voice and data • Range – 32 feet (10 meters) • Data rate – 1 Mbps www.rejinpaul.com
- 24. Zigbee • low cost and low power consumption • Radio communication for prolong period without recharging • IEEE 802.15.4 • Machine to machine network • Data rate 250kbps • Coverage range 30m • Coverage area is higher than bluetooth www.rejinpaul.com
- 25. WiMAX - • Worldwide process for Microwave access broadband wireless technology • IEEE 802.16 • Data rate 30-40 Mbps • Higher speed over greater distance www.rejinpaul.com
- 26. The Electromagnetic Spectrum Principle of wireless communication transmits and receives the electromagnetic waves Low freq radio waves 30 Hz to high freq cosmic rays (> 10 million trillion Hz) Amount of information is carried by the electro magnetic waves = width of the wavelength band Freq, wave length and speed of the waves are related by c = λ x f ‘c’ is 3x108 m/s www.rejinpaul.com
- 27. Types of electromagnetic radiation • Gamma radiation • X-ray radiation • Ultraviolet radiation • Visible radiation • Infrared radiation • Microwave radiation • Radio waves www.rejinpaul.com
- 30. Frequency bands in electromagnetic spectrum • Defined by International Telecommunication Union www.rejinpaul.com
- 32. Low frequency bands • Radio waves • Micro waves • Infrared waves • Visible light portions www.rejinpaul.com
- 33. Radio waves • Long distance communication – cross the buildings easily • Omni directional – no need to align transmitter and receiver www.rejinpaul.com
- 34. High frequency bands • X-rays • Gamma rays • Ultraviolet radiation www.rejinpaul.com
- 35. Gamma rays • Wavelength : <0.01nm • Highest frequency • Medical applications - treat the cancer patient • Produced by atomic nucleus www.rejinpaul.com
- 36. Ultraviolet radiation • Wavelength: 400 nm -10nm • Sun and hot stars emitted UV rays • VLF,LF and MF ground waves few100km • HF and VHF are observed – near the earth surface • Sky wave radio wave reflected fromthe ionosphere -- > military communication www.rejinpaul.com
- 37. X-rays • Wavelength : 0.01nm to 10nm • Temp: million to 10 million degree • Generated by super heated gas from exploding stars • Produced by accelerating electrons www.rejinpaul.com
- 38. Auctioning method • Allocated based on higher bidding company in auction Example ITU designed ISM frequency bands for unlimited usage – wireless LAN www.rejinpaul.com
- 39. Radio Propagation Mechanisms • Radio waves with different frequencies -> propagate in different ways • wave length compared to the dimension of the building • Propagation mechanisms are, Reflection Diffraction Scattering www.rejinpaul.com
- 41. Reflection • Electromagnetic waves – hit on an object (larger dimension> wavelength)- reflected wave • 180 degree phase shift b/w incident wave and reflected wave www.rejinpaul.com
- 42. Diffraction • Waves hit an edge of the object – propagated in different direction • Hit in Impenetrable (hidden) object – diffraction • Amount of diffraction is frequency dependent • Low frequency -- > diffraction more www.rejinpaul.com
- 43. Scattering • Waves hit at irregular objects ( trees, walls with rough surfaces, furniture and vehicles) • Propagate into number of outgoing weaker signal www.rejinpaul.com
- 44. Characteristics of Wireless channel • Path loss Free space propagationmodel Realistic path loss model Two-ray model • Fading Fast fading Slow fading • Interference Adjacent channel interference Co-channel interference Inter-symbol interference • Doppler shift • Transmission rate constraints Nyquist’stheorem Shannon’stheorem www.rejinpaul.com
- 45. Path loss • Ratio of transmitted power to received power • Expressed in dB • Depends on the radio frequency and nature of the ground www.rejinpaul.com
- 48. Free space propagation model • Direct path between sender and receiver • Free space path loss • Transmitted power – Pt • Transmitted gain - Gt • Received power - Pr • Received gain - Gr Relation between transmitted power and receiver power • Pr = Pt Gt Gr (λ/4πd)2 www.rejinpaul.com
- 49. Realistic path loss model • Various propagation effects • Maxwell’s equations – complex algorithms and intensive operations www.rejinpaul.com
- 50. Two-ray model • Line of sight path & reflected path Pr = Pt Gt Gr (hthr/d2)2 Pr = Pt Gt Gr (λ/4π)2 (1/dγ) www.rejinpaul.com
- 51. Fading • Fluctuations in signal strength when received by the receiver. Fast fading/ Small scale fading Slow fading/Large scale fading www.rejinpaul.com
- 52. Fast fading (different version of tx-ed signal) • Fast fluctuations in amp, phase and delay of the received signal. • Fluctuations due to ? • Interference between multiple copies of the same transmitted signal reaching the receiver at a little different times. • Occurs due to three propagation mechanisms www.rejinpaul.com
- 53. Slow fading (object blockings) • Shadow fading • Receiver inside the building or transmitted signal pass through the wall • Little variation in received power www.rejinpaul.com
- 54. Interference • Interaction of waves that are correlated with each other. • Either they travel from the same source • Or they have same frequency. • This incident occurs when two waves meet at a point while traveling along the same transmission medium. – Adjacent channel interference – Co-channel interference – Inter symbol interference www.rejinpaul.com
- 55. Adjacent channel interference • Near by freq interfere with on-going transmission signal • Avoided by using guard band www.rejinpaul.com
- 56. Co-channel interference • Narrow band interference • Same frequency can be reused by nearby systems • Avoided by multiuser detection mechanism, directional antennas and dynamic channel allocation mechanisms www.rejinpaul.com
- 57. Inter symbol interference • Distortion in telecommunication • One or more symbols interfere with other symbol • Due to multipath propagation and consequent overlapping of individual pulses – blur or mixture of signal • Adaptive equalization – allocate the time to each pulses www.rejinpaul.com
- 59. Doppler shift • Transmitter and receiver moves : – Towards – high freq – Away – low freq • Doppler shift fd =v/λ V= relative velocity between transmittter andreceiver λ= wavelength of the signal. www.rejinpaul.com
- 61. Transmission rate constraints • Todetermine the maximum data rate of transmission • Nyquist’s theorem • Shannon’s theorem www.rejinpaul.com
- 62. Nyquist’s theorem • Gives the maximum data rate of the channel (noiseless) • Number of changes (values or voltages of the transmitted signal) per second – baud rate • Ex: Transmission value 0,1,2,3 --- 00,01,10,11 C = 2xBxlog2L bits/sec B= bandwidth L= Number of discrete signal levels/ voltage levels www.rejinpaul.com
- 63. Shannon’s Theorem • Find the data rate of noise channel SNR = 10log10(S/N) Channel capacity C = Bxlog2(1+(S/N)) bits/sec www.rejinpaul.com
- 64. Basic concepts of Ad Hoc Networks •What is adhoc network ? It is a network which is formed Without any central infrastructure. •Adhoc network can be formed ? Instantly •Communication can be carried out using ? Radio waves. •Any where & Any time. •Dynamic topology •Data can be exchanged by wireless interface www.rejinpaul.com
- 65. MANET Communication • Single hop communication- direct • Multi hop communication- for away source node www.rejinpaul.com
- 66. PROTOCOLS • 1970- Norman Abramson & co – ALOHA – Single hop • 1973 – DARPA(DEFENCE RADIO) – PRNET – Multi hop • PRNET(PACKET RADIO NETWORK) – ALOHA + CSMA : to access the common wireless channel • IETF – ad hoc working group – standard protocol & functional specifications www.rejinpaul.com
- 67. Types of wireless N/W • Infrastructure based network • Infrastructure less network www.rejinpaul.com
- 68. Infrastructure based network • Nodes – fixed base station (APs) • Ex: Cellular N/W • N/W area – cells • BS – coverage area to each cell www.rejinpaul.com
- 69. Infrastructure less network • Communicate without any fixed infrastructure • MANETs and (Vehicular)VANETs • Each node act as router www.rejinpaul.com
- 70. Difference b/w cellular and ad hoc N/Ws www.rejinpaul.com
- 71. Applications of ad hoc N/W • Military applications • Emergency services Disaster relief efforts Flooded areas • Commercial applications Industries On line payment • Education Conferences Virtual class rooms www.rejinpaul.com
- 75. • Military applications soldiers – safety vehicles • Emergency services search and rescue operations also fire fighting areas • Commercial applications Data base maintenance in industry as well as on- line payment for e-commerce applications • Education For organizing conferences, meetings, lectures, virtual class rooms etc -- in universities, school & colleges www.rejinpaul.com
- 76. Design issues in ad hoc wireless N/Ws • Medium access scheme • Routing • Multicasting • Transport layer protocol • Pricing scheme • QoS • Self-organization • Security • Addressing and service discovery • Energy management • Deployment considerations www.rejinpaul.com
- 81. Medium access scheme • Distributed operation • Synchronization • Hidden terminal problem • Exposed terminal problem • Throughput Access delay • Real time traffic support • Resource reservation • Ability to measure resource availability • Capability for power control • Adaptive rate control • Use of directional antennas www.rejinpaul.com
- 82. Routing • Route selected based on hop count Requirements of routing Minimum delay Quick route configuration Loop free routing Distributed routing approach Minimum control overhead Scalability QoS Time sensitive traffic and security Major design issues Mobility Bandwidth constraint shared channel Battery power Storage capacity www.rejinpaul.com
- 83. Multicasting • What is Multicasting ? Transmission of Same message • To ? A group of mobile nodes • In ? Single transmission. Major design issues • Efficiency • Control overhead • QoS • Scalability and security www.rejinpaul.com
- 84. Transport layer protocol • Protocols are used to Set up and maintain ? End-to-end connection. • Focus on? Flow control and congestion control • What is TCP ? • Transfer Control Protocol. • It is a connection oriented protocol. • Used in ? • Wired Networks. • Performance in TCP is degraded due to frequent path breaks High mobility Bandwidth Power Channel error rate Frequent network partitions • TCP is divided into two – More packet loss www.rejinpaul.com
- 85. • Performance in TCP is degraded due to frequent path breaks High mobility Bandwidth Power Channel error rate Frequent network partitions www.rejinpaul.com
- 86. Pricing scheme • 1 (sender node)-5(receiver node) • 2(power off) • 1-2-5 (optimal path) – not effective www.rejinpaul.com
- 87. QoS • If there is a better coordination and cooperation between ? - Service provider and the user - then high QoS can be achieved. QOS can differ from application to application. • Bandwidth and delay are important parameters for ? • Multimedia applications • Identifying trusty nodes and routing packets through them are key parameters of ? • Defense applications. • Multiple link disjoint paths and availability are the key parameters of ? • Emergency and rescue operations related applications. www.rejinpaul.com
- 88. Self-organization • Self – configure • Self Organization includes ? - Neighbour discovery. - Topology organization. - reorganization • Topology can be varied – high mobility, node failures and frequent N/W partitioning • Every node maintain the updated information • Beacon signals – transferred to all nodes www.rejinpaul.com
- 89. Security • Passive attack : • Caused by ? • Malicious nodes present in the network. • Toobtain ? • Information being exchanged in network. • This type of attacks would not disturb network operation. • Active attack - disturb the N/W operation Internal attack –attackers within the network External attack - attackers external the network. • Some other security threats are ? -DoS (Denial of service) - Information disclosure and interference. www.rejinpaul.com
- 90. Addressing and service discovery • Address of mobile node is ? Globally unique identifier • Used for ? Communication in Adhoc network. • Since nodes join into a ? new network and leave from the current network any time • Any auto configuration scheme is required to ? Allocate non duplicate addresses to the nodes. • Adhoc n/w also requires ? A duplicate address-detection mechanism • In order to maintain ? Unique addressing throughout the network. www.rejinpaul.com
- 91. Energy management • In a node, • It is the process of managing ? - the sources and consumers • Of ? - energy • To ? - boost up the lifetime of the node in the network. Four categories. • Transmission power management • Battery energy management • Processor power management • Device power management • Functions of energy management mechanisms are ? • Battery life enhancing of a node • Determine the routing path with minimum energy consumption. www.rejinpaul.com
- 92. Deployment considerations • Low cost deployment • Short deployment time • Re-configurability • Non-estimation of future traffic www.rejinpaul.com
- 93. Types of Wireless Ad-hoc network • Mobile ad hoc networks • Wireless sensor networks • Wireless mesh networks www.rejinpaul.com
- 94. • Wireless Sensor Network (WSN) research has enabled large scale monitoring using small Sensors with radio links. • The technological advance in wireless communications and microelectronics has enabled the development of small, low- cost Sensor Nodes. • Wireless Sensor Networks are developed to organize and control these Sensor Nodes, which have sensing, data processing, communication and control capabilities. Information collected from these Sensor Nodes is routed to a sink Node via wireless communication approach. www.rejinpaul.com
- 100. www.rejinpaul.com
- 101. Mobile Ad Hoc Networks • Basic concepts: -Self configuring & decentralised n/w -Each node– router -Topology- dynamic topology -installation- not require preplanning MANET- interconnected to Internet -Different services to the users. www.rejinpaul.com
- 103. Design challenges of MANET www.rejinpaul.com
- 106. www.rejinpaul.com
- 107. • Networking: Wired n/ w routing protocol- not suitable for MANET Re –design protocol- Toimprove robustness and adaptability Enabling tech/ are used to provide end to end reliable data delivery. Locating receiver node is difficult- high mobility. Localization mechanism-determine location of a mobile node. www.rejinpaul.com
- 108. • Middleware and applications: Its is developed to rely on each Application to handle all the services. Specialized fields: Emergency services. Disaster recovery. Environmental monitoring. Widely used in: Home n/w search and rescue operation. Educational applications www.rejinpaul.com
- 109. MANET Operations Each node act as router Exchanges its own information to its neighbors as beacon messages Discover forwarder nodes to forward packets Broadcast the packet to all other neighbors which are in its transmission range Mobile can join the network and leave the network at any time www.rejinpaul.com
- 110. MANET Routing Process of finding path in a network Routing is a big challenging issue due to dynamic topology MANET Routing protocols Proactive or table-driven routing protocol On-demand or reactive routing protocol Hybrid routing protocol www.rejinpaul.com
- 111. Proactive or table-driven routing protocol • Each node maintains a routing table to update the details of its neighbors • Each node exchanges hello packet ( which includes node identifier, message) • Based on hello message information, node updates the routing table • Easily find the route between transmitter and receiver • Reduce the time to determine the route • Ex: DSDV(Destination sequenced distance vector) www.rejinpaul.com
- 112. www.rejinpaul.com
- 113. On-demand or reactive routing protocol • Each node determines a routing path • Each protocol uses two key phases Route discovery Route maintenance Route discovery It uses route request and route reply messages Route maintenance If reliable path is broken, route maintenancephase can be used It send the route error message to sender for intimating the broken route ex: Dynamic Source Routing Protocol Ad hoc On demand Distance Vector www.rejinpaul.com
- 114. www.rejinpaul.com
- 115. Hybrid routing protocol • It combines the advantages of proactive and reactive routing protocols • Within coverage area – Proactive • Communicate with out of coverage - Reactive • Ex: Zone Routing Protocol Order One MANET Routing Protocol www.rejinpaul.com
- 116. Applications of MANET • Commercial Environments E- commerce Business Vehicular services • Home and enterprise networking • Educational applications Set up virtual class rooms Set up communication during conferences, official meetings etc • Disaster management • Medical emergency • Military applications www.rejinpaul.com
- 117. Wsn: wireless sensor network www.rejinpaul.com
- 119. WSN Distributed network Formed by small, lightweight wireless nodes It is deployed to monitor the environment For measuring the physical parameters like temperature, pressure, humidity, sound, characteristics of objects and their motion WSN is configured automatically with out any human intervention Sensor nodes are small, powerful and inexpensive It performs multi-hop communication Coverage area is limited due to low energy and simple antenna For data transmission, each node has to form ad hoc network WSN is a special type of MANET www.rejinpaul.com
- 120. WSN : Wireless sensor network www.rejinpaul.com
- 122. www.rejinpaul.com
- 123. Subsystems of sensor node • Sensor subsystem • Processing subsystem • Communication subsystem www.rejinpaul.com
- 124. Sensor subsystem • Senses the environment www.rejinpaul.com
- 125. Processing subsystem • It performs the local computations on the sensed data www.rejinpaul.com
- 126. Communication subsystem • It is responsible for exchanging the processed message with neighboring sensor nodes www.rejinpaul.com
- 127. Advantages • Many sensor nodes are sensing same event which tends to fault tolerant • Data dissemination – Spreading information • Data gathering www.rejinpaul.com
- 128. Limitations • Cannot be protected from physical attack • have very little storage capacity • Works in short communication • It provide little energy • troubled processing power www.rejinpaul.com
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- 132. Terrestrial WSNs m e d Consists of hundreds to thousands of WS nodes. Deployed in Ad-Hoc or structured manner- communicating with base station. Sensor nodes dropped fro a plane and randomly plac into target area. In preplanned deployment, grid deployment,2-d, 3-d placement models are used. www.rejinpaul.com
- 133. Underground WSNs • No. of sensor nodes- hidden in the ground. • Monitor underground conditions. • Nodes- more expensive than terrestrial WSNs. • Maintenance, careful planning- require high cost. • Suitable components- reliable communication-soil, rocks and other mineral components. www.rejinpaul.com
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- 137. Cond… • Communication between underground sensor nodes-big challenge • Due to signal losses and high level attenuation. • Require sink nodes to fwd message from the sensor nodes to the base station. • Limited battery power-very difficult to recharge. www.rejinpaul.com
- 138. Under water WSNs • Consists of no. of sensor nodes and vehicles. • Under water vehicle are used-searching and gathering data from sensor nodes. • Sensor nodes –communicate themselves – using acoustic waves. • Acoustic waves are limited bandwidth, long propagation delay, signal fading problem. www.rejinpaul.com
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- 141. Multimedia WSNs • Used to enable tracking and monitoring purpose. • Information in the form of imaging , video and audio. • Low cost sensor nodes equipped with microphones and cameras. • Challenges-high energy consumption, high bandwidth Requirement, QoS, Data processing and compression techniques. www.rejinpaul.com
- 144. Mobile WSN • Collection of mobile nodes. • Have capability to compute, sense and communicate with physical environment. • Each mobile node can communicate with other sensor nodes if it is in the visibility of other sensor nodes. • Data can be distributed using dynamic routing. www.rejinpaul.com
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- 155. Design Challenges of Sensor Networks • 1) Sensor nodes are randomly deployed and hence do not fit into any topology. • Once deployed, do not require any human intervention. • Hence, setup and maintanence of the network should be entirely autonomous. www.rejinpaul.com
- 156. Design Issues/Challenges of WSN • 2) Sensor networks are infrastructure less networks. • Therefore, all routing and maintanence algorithms need to be distributed. www.rejinpaul.com
- 157. Design Issues/Challenges of WSN • 4) Sensor nodes are battery driven. • Difficult to change/recharge • Usually deployed in remote places. • Design based on applications to minimize the energy consumption • So as to increase the battery life. www.rejinpaul.com
- 158. Design Issues/Challenges of WSN • 3) While designing sensor node , cost is also an important factor to be considered. www.rejinpaul.com
- 159. Design Issues/challenges of WSN • 5) In forest sensor nodes would be throwing from aeroplane to deploy on ground. • In that situation, it is the responsibiltiy of sensor nodes to form ? - network - Connection Identification - Distribution www.rejinpaul.com
- 160. Design Issues/challenges of WSN • 7) Minimizing network life time for a prolong period is a major design issue in WSNs. • Thus the design of a good WSN needs to be energy efficient. www.rejinpaul.com
- 161. Design Issues/challenges of WSN • 8) Toidentify the location of sensor nodes, • Location discovery protocols are used. • It must provide accurate location. www.rejinpaul.com
- 162. Design Issues/challenges of WSN • 9) Performing secured operations using sensor network is very critical. • In ? • Miltiary areas. • Few issues are : i) Secured key exchange ii)key establishment iii)authentication iv) authorization v) secure routing vi) trust set up vii) prevention of physical attack. www.rejinpaul.com
- 163. Sensor Network Architecture • A large number of sensors deployed on different areas • Would form a network • To? • Communicate with Each other. • Each sensor has a wireless communication capability. • A sensor can gather information from? • Other sensor nodes • And can disseminate(broadcast) the processed information to? • Other sensor nodes which is in the network. • Architecture Types: – Layered – Clustured. www.rejinpaul.com
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- 166. • UNIFIED NETWORK PROTOCOL FRAMEWORK. (UNPF) • UNPF: • It integrates 3 operations in its structure: -Network initialization and Maintenance protocol - MAC - Routing protocols www.rejinpaul.com
- 167. Network initialization and Maintenance protocol • BS Can communicate with all nodes • Using ? One hop communication • Over ? Shared media. • BS broadcasts its identifier (ID) • To ? Sensor nodes using CDMA . Sensor nodes which receive the ID of BS will store the ID. • As a response message: • Each sensor node sends its ID at lowest power level. • This can be listened by BS at layer one • Because ? • All the nodes are single hop distance away from BS. • Now, the BS broadcasts control message to all the layer one nodes with their ID. • All sensor nodes send a beacon message again. www.rejinpaul.com
- 168. • Layer 1 nodes form layer two • With ? • Nodes which are one hop away from layer one nodes • And records its ID’s. • Layer -1 node inform this to ? • BS of Layer-2 nodes • Which in turn will broadcast to all the nodes. • In this manner, the layered architecture can be built by BS and Sensor nodes. www.rejinpaul.com
- 169. MAC Protocol • For the data transmission, • Distributed TDMA Receiver Oriented Channel (DTROC) assignment MAC protocol is used. • Two operations of DTROC protocol are: – Channel allocating – Channel scheduling www.rejinpaul.com
- 170. • Channel allocation: - What it is? It is the process of ? • Channel Scheduling: • Sharing of ? • Reception channel • With ? Assigning reception channel to ? every node. • Neighbours. • DTROC uses suitable channel allocating algorithms. • www.rejinpaul.com
- 171. • Separate receiving channel is assigned • for ? • each node • by ? • BS. • Each node make ? • transmission slot schedule and broadcast to ? • its neighbours • thereby enabling ? • collision free transmission and saves energy. www.rejinpaul.com
- 172. UNPF - R • It makes the sensor nodes • To ? • Vary their communication range • To ? • Improve performance. • Small transmission range would make many network partitions • Whereas, large Covered area may reduce spatial reuse of frequencies. www.rejinpaul.com
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- 174. Clustured Architecture • It organized the nodes in n/w into clusters. • Each cluster contains – Cluster head • Nodes in each cluster would Exchange message within the cluster. • Each cluster head can also communicate with the BS which is an access point and connected to a wired network. www.rejinpaul.com
- 175. Clustered architecture • Used in ? • Sensor networks to achieve data fusion. • Clustering can be extended to various numbers of depths hierarchically. • Data collected by all the cluster members can be fused to cluster head and the resulting information can be communicated to BS. • The cluster formation and the selection of cluster heads are fully autonomous and distributed process. • This could be achieved through network layer protocols such as Low-Energy Adaptive Clustering Hierarchy. www.rejinpaul.com
- 176. • What is LEACH ? • One of the clustering based protocols • What it do ? • It minimizes energy dissipation • In ? • Sensor networks. www.rejinpaul.com
- 177. UNIT-II SENSOR NETWORKS – INTRODUCTION & ARCHITECTURES www.rejinpaul.com
- 178. • In ad hoc network, • Each node contends for common shared wireless channel. • To ? Transmit data packet @ the same time • If all the nodes are starting to transmit data packet simultaneously, - Then data would be corrupted. • So , a suitable shared medium access control mechanism has to be deployed . • In a such a way that all nodes share the common channel in an efficient manner. • This task can be performed by a protocol called MAC. • Responsibility of MAC Protocol: – Transmitting data packets from one device to another device across a shared channel. www.rejinpaul.com
- 179. Responsibilities of MAC protocol • Allocation of wireless channel • To ? - Different nodes - Which are competing at the same time. • No node is waiting for prolong period. • Operation is distributed. • Performs framing, physical addressing, flow control and error control • Total available bandwidth is allocated efficiently • Hidden and exposed terminal problem has to be eliminated www.rejinpaul.com
- 180. Condt.. • Maximization of utilization of channel • Minimize the delay • Support different types of traffic • It should be robust in equipment failure and N/W failure • Require well power control • Provide QoS support • Provide time synchronization among nodes www.rejinpaul.com
- 181. Design issues • Bandwidth efficiency Bandwidth is restricted – MAC protocol is responsible- divide the bandwidth into effective manner Efficiency = bandwidth used for actual data transmission/ total bandwidth www.rejinpaul.com
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- 183. QoS support • Due to mobility of nodes from time to time QoS is not effective www.rejinpaul.com
- 184. Synchronization • Transmission between the sender and receiver nodes • has to be synchronized for ? - achieving error free -Minimized packet loss transmission. • Synchronization is also important in ? - bandwidth reservation. • It requires ? -exchange of control packets between sender and receiver. www.rejinpaul.com
- 185. Hidden terminal problem - sender nodes are hidden from each other www.rejinpaul.com
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- 192. Exposed terminal problem- -block the current transmission due to neighboring node transmit with some other node www.rejinpaul.com
- 193. Error prone shared broadcast channel • Due to each node broadcast the information to be transmitted to designated receiver----- • ----- Nodes do not start the communication • Compete many nodes at a time www.rejinpaul.com
- 194. • Lack of central coordination • Mobility of nodes www.rejinpaul.com
- 195. Classification of MAC protocols • Contention – Based Protocols • Contention based protocols with reservation mechanism • Contention based protocols with scheduling mechanism www.rejinpaul.com
- 196. • Contention – Based Protocols • Contention based protocols with reservation mechanism • Contention based protocols with scheduling mechanism www.rejinpaul.com
- 197. www.rejinpaul.com
- 199. www.rejinpaul.com
- 200. Contention based protocols • No nodes make prior reservation • When node wants to transmit to other node- compete with all other node – transmit • Do not guarantee for QoS Sender – initiated protocol Receiver – initiated protocol www.rejinpaul.com
- 201. www.rejinpaul.com
- 202. Sender – initiated protocol • Single channel sender initiated protocol- total bandwidth is not divided Multi- channel sender initiated protocol – bandwidth is divided into several channels www.rejinpaul.com
- 203. Receiver – initiated protocol If receiver node ready to receive – initiate to compete all the nodes to transmit the packets www.rejinpaul.com
- 204. www.rejinpaul.com
- 205. Contention based protocols with reservation mechanism • Provide guarantee for QoS • Reserve the bandwidth prior Synchronous protocols Asynchronous protocols www.rejinpaul.com
- 206. www.rejinpaul.com
- 207. www.rejinpaul.com
- 208. Synchronous protocol • Time synchronization among all nodes • So all nodes about reservation www.rejinpaul.com
- 209. Asynchronous protocol • Not required global time synchronization • Use relative time information make reservation www.rejinpaul.com
- 210. Contention based protocols with scheduling mechanism • Packet scheduling at nodes • Scheduling nodes for accessing the channel www.rejinpaul.com
- 211. Contention based MAC protocol • No reservation • Compete all the nodes • Node capture the channel – winning node • Protocols are, Media access protocol for wireless LAN Floor acquisition multiple access protocols Busy tone multiple access protocols MACA – by invitation Media access with reduced handshake www.rejinpaul.com
- 212. Media access protocol for wireless LAN • Protocols used in wireless LAN MACA protocol MACAW protocol www.rejinpaul.com
- 213. MACA protocol • Alternate for CSMA • CSMA- sense the channel & transmit www.rejinpaul.com
- 214. • Channel busy – wait for some time • Channel idle – transmit • Does not overcome hidden and exposed terminal problem • Utilization of bandwidth is less www.rejinpaul.com
- 215. Condt.. • Drawbacks of CSMA is overcome by MACA • It use RTS and CTS www.rejinpaul.com
- 216. www.rejinpaul.com
- 217. Solution to hidden & exposed terminal problem By MACA protocol www.rejinpaul.com
- 218. • Packet loss- transmission. • Nodes uses-Binary Exponential Back off algorithm. • In BEB mechanism- collision is detected. • Nodes doubles the maximum back-off window. www.rejinpaul.com
- 219. Solution to exposed terminal problem • B node ----- A node • B node send RTS- A node--- heard by node C • C node not actual receiver.- may not response. • C node can starts transmission www.rejinpaul.com
- 220. IEEE 802.11 • What is this ? • IEEE 802.11 refers to the set of standards • that define ? Communication • For ? wireless LANs (wireless local area networks, or WLANs). • The technology behind 802.11 is branded to consumers as Wi-Fi. www.rejinpaul.com
- 221. WLAN provides support for ? • Connection management • Link reliability • Power management in MANET. • It uses three physical layer specifications which operate in ? • 2400 to 2483.5 MHz band. • 902-928 MHz • 5.7 – 5.85 GHz region. • 3 physical layers are ? • FHSS-Frequency Hopping Spread Spectrum • DSSS-Direct Sequence Spread Spectrum • IF-Infrared Physical Layer. • It deals with Physical and MAC layer in WLAN. www.rejinpaul.com
- 222. Architecture Operates into 2 modes: • Infrastructure less mode • Infrastructure based mode. When two or more stations communicate with each other, They form, Basic service set (BSS). www.rejinpaul.com
- 223. Physical layer of IEEE 802.11 • How many physical layers defined in 802.11 ? • 3 • They are ? • Radio techniques (2) • IR (1) • Radio techniques: - 2.4 GHz ISM band. - Increases reliability & throughput www.rejinpaul.com
- 224. Physical Layer divided into? • Two sublayers: • Physical Medium Dependent sublayer (PMD) • Physical layer convergence protocol sublayer (PLCP) • PMD Performs: -Encoding, Decoding , Modulation and Demodulation of signals. • PLCP provides: -Service access point and a clear channel assignment carrier sense signal to the MAC Layer of WLAN. www.rejinpaul.com
- 225. MAC Layer • 2 MAC Protocols used in WLAN. • 1) Point Coordination Function (PCF) • 2) Distributed Coordination Function (DCF) • PCF: - Centralized scheme - Polling scheme • DCF: - Distributed scheme. - Based on CSMA/CA Hidden and exposed terminal problem can be avoided using handshaking messages : RTS & CTS www.rejinpaul.com
- 226. IFS • Time interval • Between ? the transmission • Of ? two successive frames • By ? Any node. www.rejinpaul.com
- 227. • Short Inter Frame Spacing (SIFS) • PCF Inter Frame Spacing (PIFS) • DCF Inter Frame Spacing (DIFS) • Extended Inter Frame Spacing (EIFS) www.rejinpaul.com
- 228. SIFS • Shortest IFS and takes highest priority to access the medium. www.rejinpaul.com
- 229. PIFS • The waiting time values between SIFS and DIFS. www.rejinpaul.com
- 230. DIFS • This amount of waiting time can be used by the nodes if it operates under DCF mode. www.rejinpaul.com
- 231. EIFS • Extended Inter Frame Spacing : • It is the longest IFS and gets least priority to access the medium. www.rejinpaul.com
- 232. UNIT-III WSN NETWORKING CONCEPTS AND PROTOCOLS www.rejinpaul.com
- 233. 3 www.rejinpaul.com
- 234. 4 www.rejinpaul.com
- 235. 5 www.rejinpaul.com
- 236. 6 www.rejinpaul.com
- 237. 7 www.rejinpaul.com
- 238. 8 www.rejinpaul.com
- 239. 9 www.rejinpaul.com
- 240. 10 www.rejinpaul.com
- 241. 11 www.rejinpaul.com
- 242. 12 www.rejinpaul.com
- 243. 13 www.rejinpaul.com
- 244. 14 www.rejinpaul.com
- 246. 16 www.rejinpaul.com
- 247. ISSUES IN DESIGNING ROUTING PROTOCALS FOR AD HOC NETWORKS. • Mobility • Bandwidth constraint • Error prone shared broadcast radio channel • Hidden and exposed terminal problems • Resource constraints • Security issues 17 www.rejinpaul.com
- 249. • Mobility cause frequent path break. 19 www.rejinpaul.com
- 251. Error Prone Shared • Collision occur at node because of ? • Hidden and exposed terminal problem. 21 www.rejinpaul.com
- 252. Types of ad hoc routing protocol • Proactive or table driven routing protocols • Reactive or on demand routing protocols • Hybrid routing protocols 22 www.rejinpaul.com
- 253. Proactive • Other name table driven routing protocol • Each node maintains a routing table. • Routing table contains up to date routing information of the entire network. • Whenever a node wants to send a packet to the receiver node, - it looks up in own routing table To ? Find the routing table To ? Find the routing path From ? Itself to receiver. Tables – Updated periodically. To ? Maintain the current stable/ available paths. This can be achieved by ? Exchanging or broadcasting the periodic beacon signals between nodes. So that, Each node can have the knowledge about the complete network topology. Hence, Each node can update its routing table based on beacon signal it has received from its negihbours. 23 www.rejinpaul.com
- 254. Reactive routing protocol • On demand routing protocols • Mixed: • Best features of two. 24 www.rejinpaul.com
- 255. Proactive Routing Protocols • Protocols which use the concept of Proactive routing – Destination sequenced distance vector routing protocol – Wireless routing protocol – Cluster –head gateway switch routing protocol – Fisheye state routing 25 www.rejinpaul.com
- 256. Destination sequenced distance vector routing protocol • @ DSDV Protocol in adhoc. • One of the Popular proactive routing protocols • DSDV-each node keeps record of route information- form of routing table 26 www.rejinpaul.com
- 257. Each node contains.... • ID of destination node • Details of next hop • Metric • Sequence number • Time to live parameter 27 www.rejinpaul.com
- 258. Cond... • Each route broadcast message includes • List of ID of Destination node • No of hop required • Next hop • Recent sequence number • Metric parameter 28 www.rejinpaul.com
- 259. 29 www.rejinpaul.com
- 260. • Each node updated its routing table with each other • Updation of routing in two ways *Full dump update--node sends whole routing table to neighbours-increases network over head. *Incremental update—recent update only sent-suitable-large n/w &stable- avoid heavy traffic. 30 www.rejinpaul.com
- 261. Table maintenance in DSDV • Each node receives the route information with most sequence number from other nodes • Updates its table • Nodes looks –table –to find shortest path • According to path information- each node construct another routing table • New table will broadcast • On receipt of these messages – neighbour node updates its table 31 www.rejinpaul.com
- 262. 32 www.rejinpaul.com
- 263. 33 www.rejinpaul.com
- 264. Maintaining metric field • All nodes are moving • Topology changes dynamically • Each node sent routing table update packet to its neighbours • Procedure: - Routing table update packet starts with a metric one. -Neighbour node increment this metric by 1 & rebroadcast the updated packet to neighbours. -This will be continued until all node receives update copy message - Receives more than 1 packet-select smallest metric value 34 www.rejinpaul.com
- 265. Significance of sequence number • When node receives an update packet from its neighbour node • Sequence number = or > than the sequence no.-routing packet will be updated in the table 35 www.rejinpaul.com
- 266. Wireless routing protocol • It is one of the Proactive routing protocol • When compare with DSDV , WRP differs-table maintenance & procedures in updating routing tables. • WRP- maintains 4 tables – Distance table – Routing table – Link cost table – Message re-transmission list 36 www.rejinpaul.com
- 267. 37 www.rejinpaul.com
- 268. 38 www.rejinpaul.com
- 269. 39 www.rejinpaul.com
- 270. Fisheye state routing • Each node broadcasts and exchanges the details • of ? • farthest node • Rather than ? • broadcasting neighbours information frequently in order to reduce the control overhead. 40 www.rejinpaul.com
- 271. 3 PHASES • Neighbour discovery • Information dissemination • Route Computation 41 www.rejinpaul.com
- 272. 42 www.rejinpaul.com
- 273. Reactive Routing Protocols • Dynamic source routing protocol • Ad hoc On-demand routing protocol • Temporarily ordered routing algorithm • Location aided routing • Associativity based routing • Signal stability based routing protocol • Flow oriented routing protocol. 43 www.rejinpaul.com
- 274. • Dynamic Source Routing (DSR) Protocol. • It discover a route between ? • Sender and destination when required. • Operation is based on source routing. • Sender knows complete route to reach the destination. • Each data packet carries the Source route in the packet header. 44 www.rejinpaul.com
- 275. • Since each packet carries the complete route information in the packet., • The intermediate nodes do not maintain routing information to route the packets to the destination. • Nodes which use reactive routing protocol does not maintain routing table. • Hence, number of messages exchanges between nodes is very low and hence leads to less network overhead. 45 www.rejinpaul.com
- 276. Advantage of DSR • Bandwidth usage is limited • How ? • By avoiding the periodic table updates. • However, • At the time of route discovery: • The sender node has to exchange control messages to establish a path between source and destination. • DSR protocol comprises two phases • Route discovery and Route maintenance. 46 www.rejinpaul.com
- 277. 47 www.rejinpaul.com
- 278. 48 www.rejinpaul.com
- 279. 49 www.rejinpaul.com
- 280. 50 www.rejinpaul.com
- 281. 51 www.rejinpaul.com
- 282. 52 www.rejinpaul.com
- 284. 54 www.rejinpaul.com
- 285. AODV Protocol • Ad hoc on demand routing protocols • Used in MANET. • Like DSR (Dynamic Source Routing) AODV Works in two phases. - Route discovery - Route maintenance. Only difference between DSR & AODV is: Source will not carry the complete path. Each node only knows its previous hop and next hop information of the established path. 55 www.rejinpaul.com
- 286. 56 www.rejinpaul.com
- 287. 57 www.rejinpaul.com
- 288. 58 www.rejinpaul.com
- 289. 59 www.rejinpaul.com
- 290. Temporarily Ordered routing Algorithm. (TORA) • Reactive Routing protocol. • Works on ‘link reversal algorithm’ • Main motive of TORA ? • Reduce • the transmission of ? • Control messages in mobile environment. • Performs? - Route discovery - Route maintenance - Removing route if not valid. • Every node maintains local topology based on ? • Information received from its neighbours. • In TORA, nodes have an ability to discover the network the partitions. 60 www.rejinpaul.com
- 291. 61 www.rejinpaul.com
- 292. 62 www.rejinpaul.com
- 293. 63 www.rejinpaul.com
- 294. 64 www.rejinpaul.com
- 295. 65 www.rejinpaul.com
- 296. LAR-Location aided routing • @ Geographical Routing Protocol 66 www.rejinpaul.com
- 297. 67 www.rejinpaul.com
- 298. 68 www.rejinpaul.com
- 299. 69 www.rejinpaul.com
- 300. 70 www.rejinpaul.com
- 301. 71 www.rejinpaul.com
- 303. 73 www.rejinpaul.com
- 304. 74 www.rejinpaul.com
- 306. 76 www.rejinpaul.com
- 308. Hybrid Routing Protocol • Advantages of both • Nodes are grouped into zones(region). • Nodes want to communicate within region - Act Proactive / table driven maintains routing table, path finding. • Otherwise, - Reactive / on demand. 78 www.rejinpaul.com
- 309. • Core extraction distributed adhoc routing protocol (CEDAR) • Zone Routing protocol (ZRP) • Zone based hierarchical link state routing protocol (ZHRP) 80 www.rejinpaul.com
- 310. 81 www.rejinpaul.com
- 311. 82 www.rejinpaul.com
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- 313. 84 www.rejinpaul.com
- 314. 85 www.rejinpaul.com
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- 316. 87 www.rejinpaul.com
- 317. TCP Over ADHOC n/w • Why TCP ? - reliable end-end connection - single connection b/w sender and receiver - error control - flow control Adhoc provides dynamic topology , 88 www.rejinpaul.com
- 319. 90 www.rejinpaul.com
- 320. 91 www.rejinpaul.com
- 321. TCP Explicit link failure notification 92 www.rejinpaul.com
- 322. 93 www.rejinpaul.com
- 323. 94 www.rejinpaul.com
- 324. 95 www.rejinpaul.com
- 325. 96 www.rejinpaul.com
- 326. UNIT - IV SENSOR NETWORK SECURITY www.rejinpaul.com
- 327. • Single Node Architecture: – Hardware Subsystems of sensor node. – Software Subsystems of sensor node. www.rejinpaul.com
- 328. www.rejinpaul.com
- 329. Sensor node architecture • Sensor node is a device used in sensor network for performing Data gathering Processing Communicating with other sensor nodes www.rejinpaul.com
- 330. • Sensing Unit • Processing Unit • Communication Unit • Battery www.rejinpaul.com
- 331. Architecture of a sensor node www.rejinpaul.com
- 332. Sensing unit • Measure the physical quantities (temperature, pressure etc..) • Produce analog signals. • ADC: Convert analog to digital signal • Sensor node is small size, so it consumes energy during operation. www.rejinpaul.com
- 333. Processing unit • It perform specific task, processing data and control the operation of other components in the sensor node • External memory – store the collected information • Flash memory – low cost and high storage capacity www.rejinpaul.com
- 334. Communication unit • Communication media are Radio frequency Optical communication www.rejinpaul.com
- 335. Power supply unit • Consumes power for sensing, data gathering, communicating and data processing • Sensor nodes consumes more power for data communication • Changing the sensor node can be costly • Ensure to take Adequate energy www.rejinpaul.com
- 336. Hardware subsystems of a sensor node • Computing subsystem • Power supply subsystem • Communication subsystem • Sensing subsystem www.rejinpaul.com
- 337. Computing subsystem • Each sensor node consists of microprocessor to control the sensor • Microprocessor is responsible for Executing and managing communication protocol Data processing and manipulation Error correction and encryption Digital modulation and demodulation www.rejinpaul.com
- 338. Power supply subsystem • Each sensor – battery – limited power • Power supply subsystem – monitor the amount of power used by the sensor node www.rejinpaul.com
- 339. Communication subsystem • Short range radios are used to enable the communication between sensor nodes • Transmit mode – high energy consumption • Receive mode - high energy consumption • Idle mode • Sleep mode www.rejinpaul.com
- 340. Sensing subsystem • Sensing the environment and exchanging the information with each other sensor nodes www.rejinpaul.com
- 341. www.rejinpaul.com
- 342. Software subsystems of a sensor node 1. Operating system (OS) microcode 2. Sensor drivers 3. Communication Processor 4. Communication drivers 5. Data-processing mini-apps www.rejinpaul.com
- 343. www.rejinpaul.com
- 344. Operating system (OS) microcode • OS microcode is used by High level module of node resident software • It protect the software from the machine level functionality www.rejinpaul.com
- 345. Sensor drivers • These drivers manage the key functions of transceivers which are embedded in sensors • Sensors are plug-in type • Depending upon the operating environment of sensor nodes, the configuration and settings must be installed into the sensor. www.rejinpaul.com
- 346. Communication Processor • Routing the packets • Buffering • Forwarding packets • Contention mechanisms using MAC protocols • Encryption and error correction www.rejinpaul.com
- 350. www.rejinpaul.com
- 354. Communication drivers • Transmission through radio channels • Synchronization • Encoding and decoding • Error correction and checking • Counting of bits • Signal levels • Modulation and demodulation www.rejinpaul.com
- 355. Data-processing mini-apps • It is responsible for performing data processing at node level in sensor network. www.rejinpaul.com
- 356. Data Aggregation Strategies of WSN • To avoid the usage of more resources and battery power data sensed by sensor nodes must be aggregated and disseminated to other nodes. • Collecting the information from several nodes- data aggregation • Enhance the life time www.rejinpaul.com
- 357. Continuous packet sensing and Dissemination • Does not perform actual aggregation – zero aggregation • Fixed time interval – sense the data – immediately transmit the received data to cluster head • Need fresh message – very urgent case – CPSD is required www.rejinpaul.com
- 358. Continuous packet collection and dissemination • Each node uses buffer – to store the collected and sensed data • Sensor nodes sense the data – until fill the buffer • Buffer is filled – data dissemination will be started • It reduces highly network overhead and consumption of power www.rejinpaul.com
- 359. Programmed packet collection and dissemination • Dissemination time interval is set • Buffer overflow occur before dissemination time interval, old packet is replaced by new packet • This scheme is used when not a critical case. www.rejinpaul.com
- 360. Programmed Packet aggregation and Dissemination • Each node stored only aggregated data not sensed data • Aggregation functions are AVG,MIN,MAX and STDDEV etc. www.rejinpaul.com
- 361. Programmed demand based aggregation and dissemination • On – demand basis • Whenever data is required – data can be disseminated to access point • Data gathering is done by access point www.rejinpaul.com
- 362. Weighted event and demand based data aggregation • Below or above the fixed threshold, sensed data can be stored in each node • Disseminated to cluster head • Cluster head set the weight based on distance between cluster head to sensor node • Based on the weight data can be disseminated www.rejinpaul.com
- 363. Data relaying in WSN • Event node collect the information and reported to some other node • Sink node collect the events by a node www.rejinpaul.com
- 364. Data diffusion Two steps • Interest propagation Broadcast interest (temperature) – other node maintain the received interest • Data propagation Data propagation includes the shortest path www.rejinpaul.com
- 365. Algorithms used • Flooding • Gossiping • Rumor routing • Sequential assignment routing • Directed diffusion www.rejinpaul.com
- 366. Flooding • Broadcasting the packets in the network • Every node can broadcast its own information or the information received from other nodes • Does not require any specific routing algorithm • Disadvantage: high network overhead and life time is reduced www.rejinpaul.com
- 367. Gossiping • Sending a packet to the randomly selected neighbor node • Adv: less network overhead www.rejinpaul.com
- 368. Rumor routing • Agent based routing algorithm • Packets are in the form of agents or ants disseminated among nodes to find out shortest path www.rejinpaul.com
- 369. Sequential assignment routing • It generates more number of trees • From sender node to which node has high delay and low throughput that path will be removed www.rejinpaul.com
- 370. Directed Diffusion • It improves the data diffusion • For each path gradient is assigned. • For positive path, data transmission is allowed • For negative path, data transmission is prevented www.rejinpaul.com
- 371. MAC layer protocols • Self-organizing • Hybrid TDMA/FDMA • CSMA based MAC www.rejinpaul.com
- 372. Self-organizing • Major functions are Network Initialization Link layer organization Neighbor discovery Channel assignment • It has pair of time slots at a fixed frequency • Each communication link has different frequency • A channel is assigned to each link • No interference between nodes due to large bandwidth • Power can be saved while idle slot – turned off; data transmission slot – turned on. www.rejinpaul.com
- 373. Hybrid TDMA/FDMA • Communicate nearby fixed station • FDMA: Each cluster head uses fixed frequency Neighboring nodes does not have same frequency TDMA: Allot the time slot to the sender node Transmitter in idle – power off Receiver use more power for time synchronization www.rejinpaul.com
- 374. CSMA based MAC • S-MAC • T-MAC • D-MAC • B-MAC • X-MAC • Wise - MAC www.rejinpaul.com