23-1©2010 Raj JainCSE574sWashington University in St. LouisWireless Mesh and Wireless Mesh and MultiMulti--Hop Relay Hop Relay NetworksNetworksRaj Jain Washington University in Saint LouisSaint Louis, MO [email protected]/Video recordings of this lecture are available at:http://www.cse.wustl.edu/~jain/cse574-10/23-2©2010 Raj JainCSE574sWashington University in St. LouisOverviewOverview Multi-Hop Relay Networks 802.16j Mobile Multi-hop Relay (MMR) 802.15.5 WPAN Mesh Networking 802.11s Mesh Networks: Applications Wi-Fi Mesh Products23-3©2010 Raj JainCSE574sWashington University in St. LouisMultiMulti--Hop NetworksHop Networks Relay: Dedicated carrier owned infrastructure, Tree based topology. One end of the path is the base station Mesh: Routing by subscriber equipment, Multiple connections, mesh topologyRef: http://en.wikipedia.org/wiki/Mesh_networking23-4©2010 Raj JainCSE574sWashington University in St. LouisMultiMulti--Hop Relay NetworksHop Relay Networks Next generation networks need very high data rates Data rate ∝ 1/distance ⇒ High density of cell towers ⇒ High cost Multi-hop Networks have fixed infrastructure ⇒ Do not need complex routing techniques Relays are low-cost low transmit power and have no connection to wired infrastructure More capacity due to shorter distances and frequency reuse Goal: High capacity and coverage (not absence of infrastructure)BaseRelayMobile Host23-5©2010 Raj JainCSE574sWashington University in St. LouisCoverage ExtensionCoverage Extension Side streets can be covered by relays A series of relays can be used to forward traffic to base Relaying either in time domain or frequency domainBaseRelayMobile23-6©2010 Raj JainCSE574sWashington University in St. LouisThroughput EnhancementThroughput Enhancement Virtual Antenna Arrays Multiple cooperating relays act as distributed MIMO Challenges: Synchronization, Sharing of Channel State Information3×2 MIMO23-7©2010 Raj JainCSE574sWashington University in St. LouisiCARiCAR Integrated Cellular and Ad-Hoc Relaying System Relaying stations are used to divert traffic from congested cells to nearby lightly loaded cells Even existing calls can be moved ⇒ Secondary relaying23-8©2010 Raj JainCSE574sWashington University in St. Louis802.16j Mobile Multi802.16j Mobile Multi--hop Relay (MMR)hop Relay (MMR) Three types of Relays: Fixed, Nomadic (special events, Indoor), Mobile Relays (Trains)23-9©2010 Raj JainCSE574sWashington University in St. Louis802.16j Technical Issues802.16j Technical Issues Centralized vs. distributed control: Functional division between Base and Relay Scheduling Radio Resource management Power Control Call Admission and Traffic Shaping Policies QoS: Network wide load balancing, Congestion control Security ManagementNote: Routing is not an issue with fixed relays23-10©2010 Raj JainCSE574sWashington University in St. LouisMultiMulti--Hop Relay Networks: SummaryHop Relay Networks: Summary Relay concept applies to Cellular Networks and to Wireless Access Relays can help overcome obstacles Relays help improve the capacity by decreasing the distance Relays help decrease the cost since they are much cheaper than base stations Routing with fixed relays is simple Increasing delays ⇒ Number of hops must be limited to two or three Distributed MIMO ⇒ Improvement in data rates23-11©2010 Raj JainCSE574sWashington University in St. LouisMesh NetworksMesh Networks WPAN Mesh: 802.15.5 WLAN Mesh: 802.11s23-12©2010 Raj JainCSE574sWashington University in St. Louis802.15.5 WPAN Mesh Networking802.15.5 WPAN Mesh Networking Goal: Range Extension, Routing Redundancy Issues:¾ Handle Multiple Master devices¾ Handle multiple super frame coexistence¾ Fair sharing of channel time¾ Minimal changes to 802.15.3 and 802.15.4Mesh Control and Data pathPiconets23-13©2010 Raj JainCSE574sWashington University in St. Louis802.11s Mesh Networks: Applications802.11s Mesh Networks: ApplicationsCMTSSSMSOs/CLEC/Municipal10/100/1000 MbpsInternet100/1000 MbpsEnterprise CampusEmergency ResponseHome Networks23-14©2010 Raj JainCSE574sWashington University in St. Louis802.11s Device Classes802.11s Device Classes Stations (STA): Non-mesh capable station Mesh Points (MP): Mesh capable station Mesh AP (MAP): MP + AP Mesh Portal (MPP): Entry/exit to wired network. Support transparent bridging, address learning, and bridge-to-bridge communication (spanning tree etc). Root Portal: MPP configured for topology building. Elected to become the root of the default forwarding tree MPMAPMPPSTABridge/RouterMPMPRef: http://en.wikipedia.org/wiki/IEEE_802.11s23-15©2010 Raj JainCSE574sWashington University in St. Louis802.11s Hybrid Wireless Mesh Protocol802.11s Hybrid Wireless Mesh Protocol Two Configurations: With Root Portal and Without Root PortalRoute Discovery: W/O Root Portal: ¾ On-demand Radio Metric AODV (RM-AODV)Cost = Amount of air time consumed per packet transmission¾ Radio Aware OLSR Path Selection Protocol (Optional)Frequency of LS forwarding is reduced with hops(Fish eye state routing) W Root Portal: Most of the traffic is to the root.¾ Proactive. Tree based distance vector routing.23-16©2010 Raj JainCSE574sWashington University in St. LouisCommon Channel FrameworkCommon Channel Framework All stations use a single control channel Stations dynamically select the data channel They announce it on the common control channel using RTX/CTX (Not RTS/CTS) packets23-17©2010 Raj JainCSE574sWashington University in St. Louis802.11s Examples802.11s Examples59710643218X59710643218X4->94 sends RREQ9 sends RREP4->X4 sends RREQNo Resp ⇒ 4 forwards to MPP 123-18©2010 Raj JainCSE574sWashington University in St. Louis802.11s Examples802.11s Examples59710643218X59710643218X4->X4 forwards to MPP1MPP1 sends to X4->94 forwards to MPP1MPP1 sends to 99 Issues RREQ4 sends RREP23-19©2010 Raj JainCSE574sWashington University in St. LouisWiWi--Fi Mesh ProductsFi Mesh Products LocustWorld.com¾ MeshAP S/W: Freeware from locustworld.com. Allows computers to act as wireless routers.¾ Uses AODV protocol. Problem of false DVs.¾ MeshBox: Complete hw/sw package¾ MeshBox 2 or MexBox: Uses two Wi-Fi radio modules. Successive routers could share a channel, e.g., 1+2, 2+3, 3+1 among three routers. FireTide Network: ¾ HotPort 4.9 GHz Public Safety Mesh Nodes, ¾
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