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1. INTRODUCTION

1. INTRODUCTION. WIRELESS NETWORKS. Wireless Networking. Single Hop. Multi-hop. Infrastructure-based (APs). Infrastructure-less (Ad Hoc). Hybrid. Infrastructure-less (MANETs). 802.11. 802.16. 802.11. Bluetooth. Cellular Networks. VANETs. Wireless Sensor Networks.

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1. INTRODUCTION

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  1. 1. INTRODUCTION

  2. WIRELESS NETWORKS Wireless Networking Single Hop Multi-hop Infrastructure-based (APs) Infrastructure-less (Ad Hoc) Hybrid Infrastructure-less (MANETs) 802.11 802.16 802.11 Bluetooth Cellular Networks VANETs Wireless Sensor Networks WIRELESS MESH NETWORKS

  3. ARCHITECTURE of WMNs • WMNs consist of two types of nodes: Mesh Routers and Mesh Clients • A wireless mesh router contains additional routing functions to support mesh networking • Same coverage as a conventional router but with much lower transmission power through multi-hop communication

  4. Mesh Routers

  5. Zigbee Mesh Router @ BWN Lab

  6. Mesh Routers

  7. Mesh Routers

  8. MESH CLIENTS

  9. Network Architecture Classification 1. INFRASTRUCTURE MESHING 2. CLIENT MESHING 3. HYBRID MESHING

  10. INFRASTRUCTURE MESHING

  11. CLIENT MESHING

  12. HYBRID MESHING

  13. IEEE 802.11 Based Mesh Network Wired Network Ri Mesh Point (MP) Gi Mesh Point Portal (MPP) Ai Mesh Access Point (MAP) G2 G1 R2 R1 R3 A2 A1 A3

  14. CHARACTERISTICS (Required) • Multi-hop Wireless Network • Support for Ad Hoc Networking • Capability of Self-Forming, Self-Healing, and Self- Organization • Compatible and Interoperable with Existing Wireless Networks

  15. CHARACTERISTICS (Typical) • Multiple radios and multiple channel systems • Advanced radio techniques: Directional and smart antennas, MIMO system, reconfigurable radios, frequency agile/cognitive radios, software radios • Multiple Types of Network Access (WiMAX, WiFis)

  16. WMNs vs Ad Hoc Networks Dedicated Routing and Configuration: • In ad-hoc networks, end-user devices also perform routing and configuration functionalities for all other nodes. • However, WMNs contain mesh routers for these functionalities.  the load on end-user devices is significantly decreased,  lower energy consumption and high-end application capabilities • End-user requirements are limited  decreases the cost of devices in WMNs

  17. WMNs vs Ad Hoc Networks Multiple Radios: * Multiple radios perform routing and access functionalities * Example: One radio  routing between mesh routers Another radio  access to the network from end-users  significantly improves the capacity of the network * These functionalities are performed in the same channel in ad-hoc networks  performance affected !

  18. WMNs vs Ad Hoc Networks Mobility: (in ad hoc networks) • Routing is realized by end-user devices  the network topology and connectivity depend on the movement of users  Additional challenges on * routing protocols * network configuration and * deployment

  19. WMNs vs Ad Hoc Networks Mobility: (in WMNs) • Since mesh routers provide the infrastructure, the coverage can be engineered easily. • While providing continuous connectivity throughout the network, the mobility of end-users is still supported, without compromising the performance of the network.

  20. WMNs vs Ad-Hoc Networks Wireless Mesh Networks Ad-Hoc Networks • Multihop • Nodes are wireless, possibly mobile • May rely on infrastructure • Most traffic is useruser • Multihop • Nodes are wireless, some mobile, some fixed • It relies on infrastructure • Most traffic is usergateway

  21. WMNs vs WIRELESS SENSOR NETWORKS Wireless Sensor Networks Wireless Mesh Networks • Bandwidth is high (>1Mbps) • Some nodes mobile, some fixed • Not energy limited • Resources are not an issue • Most traffic is user-to-gateway • Bandwidth is limited (tens of kbps) • In most applications, fixed nodes • Energy constraints • Resource constraints • Most traffic is user-to-gateway

  22. * Low up-front costs* Easy incremental deployment* Easy maintenance* Provide NLOS coverage* Wireless AP backbone provides connectivity and robustness which is not always achieved with selfish and roaming users in ad-hoc networks* Take load off of end-users* Stationary APs provide consistent coverage ADVANTAGES OF WIRELESS MESH NETWORKS

  23. Applications: Broadband Home Networking • Current home network realized through IEEE 802.11 WLANs • Problem  location of the access points • Homes have many dead zones without service coverage • Site surveys are expensive and not practical • Installation of multiple access points is also expensive and not convenient • Communications between nodes under two different access points have to go through the access hub, not an efficient solution

  24. Applications: Broadband Home Networking WMN is the SOLUTION!

  25. Applications: Community and Neighborhood Networking Community networks based on cable, DSL and last-hop wireless • All traffic must flow through Internet  significantly reduces network resource utilization. • Large percentage of areas in between houses is not covered by wireless services • Gateways may not be shared and wireless services must be set up individually, network service costs may increase • Each home has single path to access Internet

  26. Applications: Community and Neighborhood Networking WMNs can mitigate these disadvantages and provide many applications such as distributed file storage, distributed file access, and video streaming.

  27. Applications: Enterprise Networking • IEEE 802.11 WLANs • Isolated islands, connections among them are achieved through wired Ethernet • Adding more backhaul access modems only increases capacity locally • Does not improve robustness to link failures, network congestion and other problems

  28. Applications: Enterprise Networking • WMNs Solutions • Multiple backhaul access modems can be shared by all nodes in the entire network • Scalable

  29. Applications: Metropolitan Area Networks • WMNs provide higher transmission rate than cellular networks • Communication between nodes does not rely on a wired backbone • An economic alternative to broadband networking • Covers larger area than home, enterprise, building, or community networks • Higher scalability

  30. Applications: Metropolitan Area Networks

  31. Applications: Transportation Systems • WMNs can extend access from stations into buses, ferries, and trains. • Convenient passenger information services, remote monitoring of in-vehicle security video, and driver communications. • Two key techniques are needed • High-speed mobile backhaul from a vehicle to the Internet • Mobile mesh networks within the vehicle.

  32. Applications: Transportation Systems

  33. Applications: Building Automation • Various electrical devices need to be controlled and monitored. • Standard wired networks is very expensive • Wi-Fi networks can reduce the cost of such networks • However, Wi-Fis are still expensive • Low deployment cost of BACnet (Building Automation and Control Networks) with WMNs

  34. Applications: Building Automation

  35. Application: Broadband Internet Access

  36. Qualitative Comparisons for Broadband Internet Access Very Good Very Good Bandwidth Limited Good Upfront Investments Very High Low High High Total Investments Very High Moderate High High Market Coverage Modest Good Good Good Cellular (2.5-3G) Cable DSL WMAN (802.16) WMNs

  37. Mobile Internet Access • Direct competition with 3G cellular systems

  38. Qualitative Comparisons for Mobile Internet Access Upfront Investments High Low Bandwidth Limited Good Geo-location Limited Good Upgrade Cost High Low Cellular 3G WMNs

  39. Applications: Health and Medical Systems • Monitoring and diagnosis data need to be processed and transmitted across rooms for various purposes • Large data volume by high resolution medical images, various periodical monitoring information • Wi-Fi based networks must rely on the existence of Ethernet connections, cause high system cost, complexity and dead spots • However, these issues do not exist in WMNs

  40. Applications: Security and Surveillance Systems • Security surveillance systems are necessary for enterprise buildings, shopping malls, grocery stores, etc. • Still images and videos are the major traffic flowing in the network • They demand much higher network capacity than other applications • WMNs are a good solution for these applications

  41. More Applications • Disaster Relief and Emergency Networks • P2P Networking

  42. ANOTHER APPLICATION: Hybrid Network Architecture for Electrical System Automation • Wireless Automatic Meter Reading (WAMR): • Energy consumption statistics • Effective billing management • Remote activation and deactivation of the customer services Project No.04-157: Communications Infrastructure for Electric System Automation

  43. ANOTHER APPLICATION: Hybrid Network Architecture for Electrical System Automation • Electric System Monitoring: • Equipment (e.g., distribution transformer, feeder, recloser/sectionalizer, capacitor, etc.) monitoring • Fast identification of service interruptions and incipient faults • Timely restoration of the electric utility services Project No.04-157: Communications Infrastructure for Electric System Automation

  44. ANOTHER APPLICATION: Hybrid Network Architecture for Electrical System Automation Project No.04-157: Communications Infrastructure for Electric System Automation

  45. Applications: Layer 2 Connectivity Internet • The entire wireless mesh cloud becomes one (giant) Ethernet switch • Simple, fast installation • Short-term events (e.g., conferences, conventions, shows) • Where wires are not desired (e.g., hotels, airports) • Where wires are impossible (e.g., historic buildings)

  46. Qualitative Comparisons Layer 2 Connectivity Speed/Ease of Deployment Slow/Difficult Fast/Easy Very Good Bandwidth Good Mobile Users 802.11 needed support Total Cost Moderate Low-Moderate Ethernet WMN

  47. Critical Factors influencing Network Performance 1. Advanced Radio Techniques Typical Examples: * Directional and smart antennas * MIMO systems  (Key Technology for IEEE 802.11n) * Multi-radio/multi-channel systems * Reconfigurable radios More Advanced Technologies (not mature yet for commercialization): * Frequency agile/cognitive radios and * Software radios These advanced radio technologies require revolutionary design in higher layer protocols, in particular, MAC and routing.

  48. Critical Factors Influencing Network Performance 2. Scalability (NW performance degrades with increasing NW size) e.g., throughput degrades with the number of hops. Max. available bandwidth degrades at the rate of 1/2,1/4,1/8 depending on the number of hops; 4 hops away from the sender the max BW becomes 1/16 of the total available BW.

  49. Critical Factors Influencing Network Performance 3. Mesh Connectivity (for protocol design) 4. Broadband and QoS (end-to-end delay, fairness, delay, jitter, aggregate and per-node throughput, packet loss ratios) 5. Compatibility and Inter-Operability (for mesh and conventional clients; mesh routers must be capable for inter-operation)

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