Wireless networks - Lecture 31: Wireless mesh networks (Part 1). The main topics covered in this chapter include: introduction to WMN; characteristics; WMN vs MANET; architecture; applications; critical factors influencing performance; dynamically self-organized and self-configured;...
Wireless Networks Lecture 31 Wireless Mesh Networks Dr Ghalib A Shah Outlines Introduction to WMN Characteristics WMN vs MANET Architecture Applications Critical factors influencing performance ► Radio techniques, scalability, QoS, security, Ease of Use, Mesh connectivity Last Lecture Limitations of QoS in IEEE 802.11 Overview of 802.11e Traffic Categories EDCF HCF Mobile IP ► ► ► ► ► Care-of-address, MIP Protocol (Discovery, Registration, Tunneling) Routing Inefficiencies MIPv6 Introduction Wireless mesh networks (WMNs) comprised of mesh routers and clients Mesh clients not only work as host but also perform routing for multi-hop destinations Mesh routers support bridge/gateway functionalities enabling integration of WMNs with existing wireless networks such as cellular, WSN, WiMAX etc WMN is dynamically self-organized and self-configured Conventional nodes e.g PC, PDA, PocketPC, phones , equipped with wireless NIC can connect directly to mesh routers Without Wireless NIC, Ethernet connection is also possible Thus WMN will allow always-on-line anywhere anytime Gaining interest as a possible way of ISPs Can be deployed incrementally as needed Source: NC State university, dept of computer engineering Deploying WMN is not difficult because most of the components/protocols are readily available to some extent e.g IEEE 802.11, WEP etc However scalability in existing protocol is a great concern Characteristics Multi-hop ► To extend the coverage range of wireless networks without sacrificing the channel capacity and non lineof-sight Support for ad hoc networking ► Due to flexible architecture, easy deployment and configuration, fault tolerance and mesh connectivity is possible ► Low up-front investment requirements Mobility dependence on type of mesh nodes ► Mesh routers usually have minimal mobility ► Mesh clients can be stationary or mobile Multiple type of network access ► Both backhaul access to internet and P2P communication are supported ► Integration of WMN with other wireless networks allow endusers access to WMN Dependence of power-consumption constraints on the type of mesh nodes Compatibility and interoperability with existing wireless networks ► WMN based on IEEE 802.11 should support both mesh clients as well as Wi-Fi clients ► It should also be interoperable with other networks 10 WMN Clients Examples of mesh clients: (a) Laptop, (b) PDA, (c) WiFi IP Phone and (d) WiFi RFID Reader 17 Infrastructure/backbone WMNs Built using various wireless technologies in addition 802.11 With gateway functions, mesh router can connect to internet 18 Infrastructure meshing allowing integration of different networks If client has different technology then it can connect through BS and BS through Ethernet The most common type For example, community and neighborhood networks can be built ► ► ► ► Mesh routers can be placed on the roof of houses Serve as access point for users inside the house and along the roads Two types of radio; one for backbone and other for users Backbone communication can be established using long range and end-user using short range 19 Clients WMNs Client meshing provides P2P network among client devices No mesh router required Clients in this arch require more functionalities for configuration and routing Formed using single radio 20 Hybrid WMNs Combination of infrastructure and client meshing Most applicable/practical scenario 21 Application scenario Research and development in WMNs is motivated by several applications which can be supported on cellular, WiMAX etc 22 Broadband home networking WLAN is not practical because AP leave dead zones and multiple APs require backbone network or access hub Dead zones can be eliminated with multiple routers and adjusting their transmission power 23 Community and neighborhood networking 24 The common architecture is to use cable or DSL through internet It has drawbacks ► ► ► ► All traffic must flow through internet Dead zones Services between end-users can not be shared Single path for internet and neighborhood user 25 Enterprise networking Scalable with enterprise growth 26 Other applications Transportation system ► Instead of limiting access to stations, WMNs can extend access into buses, trains, ferries ► Remote monitoring of in-vehicle security video and passenger information system Building automation Health and medical system Security surveillance system 27 Critical factors influencing network performance Radio techniques ► ► ► ► Directional and smart antennas MIMO systems Multi-radio chipsets More advanced techniques such as reconfigurable radios, cognitive radios ► These require revolutionary design changes in higher layers 28 Scalability ► Multihop routing is common in WMN, which degrades performance ► IEEE 802.11 MAC is not scalable and throughput significantly reduces as number of hops increases to or higher Mesh connectivity ► Network self-organization and topology control algorithms are needed 29 Broadband and QoS ► Different from ad hoc networks, most applications of WMN are broadband services with various QoS requirements Compatibility and inter-operability ► Network access to both conventional and mesh clients Security ► No centralized control Ease of use 30 Summary Introduction to WMN Characteristics WMN vs MANET Architecture Applications Critical factors influencing performance ► Radio techniques, scalability, QoS, security, Ease of Use, Mesh connectivity 31 ... MIPv6 Introduction Wireless mesh networks (WMNs) comprised of mesh routers and clients Mesh clients not only work as host but also perform routing for multi-hop destinations Mesh routers support... other wireless networks allow endusers access to WMN Dependence of power-consumption constraints on the type of mesh nodes Compatibility and interoperability with existing wireless networks. .. fault tolerance and mesh connectivity is possible ► Low up-front investment requirements Mobility dependence on type of mesh nodes ► Mesh routers usually have minimal mobility ► Mesh clients can