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Transcript
Integrating UMTS and Mobile Ad Hoc Networks MASc. Student: Jade Wu Computer Networks, Department of Electrical and Computer Engineering, Ryerson University Supervisor: Dr. Muhammad Jaseemuddin Sep 21, 2005 1 Presentation Contents Background Design Details Simulation & Results Conclusion Q&A 2 Wireless Communication Systems 2G – 2.5G 3G 4G GSM – GPRS UMTS WLAN Integrating the existing wireless technologies 3 Motivation Packet-Switched External Packet Switched Network SGSN GGSN UMTS Network External Circuit Switched Network Wide area coverage, but low data rate Speed: hundreds kbps MSC/VLR RNC GMSC Circuit-Switched Email (PS) Phone call (CS) Node B Hot Spot Coffee Shop Local area coverage, high data rate Speed: ~ 54 Mbps 802.11 Router User moves to a hot spot. Can we use this high-speed connection for PS services? Different ISPs? Different interfaces? 4 Objective Integrating UMTS and ad hoc network Two interfaces UMTS interface: always on 802.11 interface: on when MN detects 802.11 beacons Integration point is located in UMTS CN. (operated by the same ISP) Inter-system handover procedures occur when MN moves in or out of 802.11 local area. 802.11 ad hoc mode enhances flexibility (ondemand routing and multihop features) Internet UMTS Connection 802.11 Connection CN UMTS BS Ad hoc Gateway 802.11 Beacon ON UMTS Interface OFF 802.11 Interface ON UMTS Interface ON !!! 802.11 Interface 5 Presentation Contents Background Design Details Simulation & Results Conclusion Q&A 6 Overview Key Approaches UMTS Core Network Internet SGSN GGSN SGSN Signaling RNC Ad hoc network Node B Gateway UTRAN PS MI ig li na ng Integration point: GGSN Apply SGSN signaling for communication between UMTS CN and ad hoc netowrk Inter-SGSN handover GTP tunneling Apply MIP signaling for ad hoc mobility management Gateway discovery Route discovery 7 Signaling between UMTS and Ad hoc networks Why not IP Signaling? Full MIP structure: HA (any GSN) FA (Gateway)+ MN Modifying GSNs is costly and risky. No official standard for implementing MIP on GSNs. SGSN Signaling Ad hoc gateway acts as SGSN. GGSN is the integration point. Apply inter-SGSN handover signaling between new SGSN, old SGSN and GGSN. (standard by 3GPP) Use GTP tunneling between GGSN and ad hoc gateway Maintain 3GPP standard in UMTS CN with some minor modifications Modifying ad hoc gateways is less expensive. UMTS Core Network UMTS Core Network Internet Internet SGSN SGSN GGSN/HA GGSN MIP SGSN Signaling Signaling RNC RNC Node B Node B Gateway/SGSN Gateway/FA Ad hoc network UTRAN Ad hoc network UTRAN 8 Ad Hoc Mobility Management MIP signaling is used for ad hoc mobility management. Gateway acts as a FA. All the mobile nodes must register with the gateway. Registration procedure is simplified. No home registration. Gateway Discovery Receive ad hoc beacons from neighbours Send out Gateway Query (Route Request for “All Mobility Agents”) Receive Gateway Reply from the neighbour who knows gateway or gateway itself Send Registration Request to the gateway After Registration Reply is received, Mobile IP installs a default route to the gateway. Receiving a Router Advertisement directly triggers registration process. 9 Ad Hoc Mobility Management Ad hoc forwarding is modified. Route Discovery: Network ID: Carrying a different network ID means the destination must be located in the Internet. Routing Table: Host route found means the destination is in ad hoc network. Destination is unknown: Forward the packet to the gateway. Gateway determines whether or not this destination is in ad hoc network. If so, gateway sends back error message to inform the sender to perform ad hoc route discovery. If not , gateway tunnels the packet to GGSN. Packet Ready to send. Determine Destination Add. Same Network ID? No Yes Routing Table Lookup. Find Host Route? Forward Packet via Default Route No Yes Forward Packet via Next Hop Perform Route Discovery in Ad hoc Network 10 Inter-System Handovers: UMTS-MANET Handover When MN moves in an area where it receives ad hoc beacons from other ad hoc nodes Perform gateway discovery in ad hoc network Registration message triggers inter-system handover Inter-SGSN handover between new SGSN (ad hoc gateway) and old SGSN (SGSN) Buffering is enabled on SGSNs. Receiving a Router Advertisement directly triggers the registration process. MNx MN MN Gateway Gateway SGSN SGSN GGSN GGSN Ad hoc Beacon Gateway Discovery Router Advertisment RARP RARP Reply Registration Request with IP@ of MNx Gateway Discovery Gateway Query SGSNaddress Context Request (unicast RREQ to MNx asking for mutlicast "All Mobility Agents") SGSN Context Response Gateway Reply Buffer (unicast RREP with Gateway info back to MN) Inter-SGSN Handover SGSN Context Ack Registration Request MIP Signaling Forward Packets Buffer SGSN Context Request Update PDP Context Request SGSN Context Response Inter-SGSN Handover Buffer Response Update PDP Context MIP Signaling SGSN Context Ack Registration Reply Forward Packets Buffer Update PDP Context Request Update PDP Context Response Registration Reply 11 Inter-System Handovers: MANET-UMTS Handover When MN moves out of ad hoc network Missing beacons causes registration entry to expire and triggers intersystem handover Perform inter-SGSN handover procedure between new SGSN(SGSN) and old SGSN (ad hoc gateway) MNx MN Gateway SGSN GGSN No Ad hoc Beacon No Registration Request Registration Entry Expires Routing Area Update Request SGSN Context Request SGSN Context Response Inter-SGSN Handover Buffer SGSN Context Ack Forward Packets Buffer Update PDP Context Request Update PDP Context Response Routing Area Update Accept Routing Area Update Complete 12 Addressing & Tunneling Packet Switched Network (Internet) Addresses for Links to Internet: Assigned by ISP (public addresses) n Tun GTP elin g GGSN GTP Tunneling UMTS Core Network RNC UTRAN GTP Tunneling SGSN Addresses in Core Network: Assigned by ISP (private or public addresses) Gateway WLAN/ Ad hoc MN Addresses for MNs in Adhoc: Assigned by Mobile Agent (care-of addresses) MN Addresses for MNs in UTRAN: Assigned by GGSN (home addresses) 13 Presentation Contents Background Design Details Simulation & Results Conclusion Q&A 14 Simulation Properties Simulation tool: OPNET 10.5 Simulation area: 3km x 3km Simulation duration: 3,600 secs (1 hour) Ad hoc node transmission range: 200 meters No. of ad hoc nodes in MANET: 0, 2, 4, 6, 8, 10 Traffic: CBR: Packet size: 128 bytes Packet arrival rate: 200, 400, 600, 800 packets/ sec FTP: File size: 30000, 85000, 200000 bytes Inter-request time: 30 secs 15 Simulation Timeline and Trajectory Attach UMTS Power-up Node B RNC MANET-UMTS UMTS-MANET Handover Handover SGSN UMTS CN UTRAN Registration Internet Gateway GGSN Ad hoc network Simulation Timeline (minute) 0 10 11 41 42 60 16 Results UMTS-MANET Handover Time GGSN 2 SGSN Context Requet 3 SGSN Context Response SGSN Gateway 4 SGSN Context Ack 120 100 80 60 40 20 0 0 2 4 6 8 10 12 d1 MN 7 Reqistration Reply handover _ time 2d1 3d 2 2d 3 1 Registration Request d2 Handover Time (msecs) 140 d3 5 Update PDP Context Response 6 Update PDP Context Request UMTS-MANET Handover Time No. of MANET nodes MN where d1 No_of_intermedia_nodes 17 Results MANET-UMTS Handover Time GGSN 5 Update PDP Context Response 6 Update PDP Context Request d3 2 SGSN Context Requet 3 SGSN Context Response SGSN Gateway 4 SGSN Context Ack 7 Routing Area Update Accepted 1 Routing Area Update Request d1 MN d2 Handover Time (msecs) MANET-UMTS Handover Time 90 80 70 60 50 40 30 20 10 0 0 2 4 6 8 10 12 No. of MANET Nodes handover _ time 2d1 3d 2 2d 3 where d1 is the transmission delay between SGSN and MN 18 Results Throughput (file size = 30,000 bytes) Max: 48,000 Average data rate: 8kbps 19 Results Throughput (file size = 85,000 bytes) 2.8 times Average data rate: 22.6kbps 20 Results Throughput (file size = 200,000 bytes) Buffer/Retransmission 6.8 times Average data rate: 53.3 kbps > Max. bit rate 48kbps 21 Results Packet Loss Packets start to be dropped when buffer is overflow during handovers. Default buffer size = 8172 bytes. Total Packet Dropped During MANET-UMTS Handover Total Packet Dropped During UMTS-MANET Handover 70 80 60 70 40 10 mobile nodes 30 8 mobile nodes 20 6 mobile nodes 10 4 mobile node 0 2 mobile nodes 0 mobile nodes 200 400 600 800 1000 60 No. of MANET nodes 50 10 mobile nodes 30 40 8 mobile nodes 20 6 mobile nodes 10 4 mobile node 0 2 mobile nodes 0 mobile nodes 200 Packet Arrival Rate(packets/sec) No. of Packet Dropped No. of MANET nodes No. of Packet Dropped 50 400 600 800 1000 Packet Arrival Rate (packets/sec) overflow _ byte _ during _ handover(bytes) handovertime(sec) packet _ arrival _ rate( packets sec) packet _ size (bytes packet ) 22 Throughput (file size= 85,000) 2 mobile nodes move randomly. 23 Throughput (file size= 85,000) 5 mobile nodes move randomly. 24 Presentation Contents Background Design Details Simulation & Results Conclusion Q&A 25 Conclusion We assume that a mobile node is equipped with two interfaces – a UMTS interface and a MANET interface. We consider MANET is connected to UMTS CN and integrated at GGSN. We developed vertical handover scheme for a mobile node to move from UMTS to MANET and vice versa. We addressed the issue of signaling and Quality of Service during the intersystem handover. 26 Conclusion We developed a simulation model of the integrated system in OPNET and evaluated the performance of the integrated system under variety of scenarios. We analyzed the results and concluded as the following: Tolerable handover delays Significant throughput improvement Low packet loss rate The purpose of this research relates to the idea of improving data transmission rates and mobility in existing wide area network (UMTS). For mobile hosts in an ad hoc network to enjoy the connectivity from both networks and be able to switch some types of services (i.e. packet data service) which require higher capacity to the 802.11 links. 27 Presentation Contents Objective Design Details Simulation & Results Conclusion Q&A 28 Thank you for attending my presentation. Questions? 29 THE END 30 Why release buffer before Update PDP Context? Distribute the packet load to both side buffers. Both SGSNs are enabled with buffering. This way keep the packets in order. Packets can be forwarded from the GGSN and old SGSN during handover. 31 Why early expiration? Missing beacons means mobile node has left the ad hoc network. Therefore should perform handover immediately in order to minimize the packet loss or delay Why not on gateway side? Gateway will be informed by new SGSN with the SGSN context request during the handover. Could be a period of time gateway still sees mobile node is reachable 32 How buffer works? In SGSN the packets will be assigned NPDU before being sent. When SGSN received a SGSN Context Request, the SGSN stop assigning N-PDU for the downlink PDUs toward this mobile node. Unsigned PDU will be put into buffer. 33 How multicast address works for gateway discovery Multicast address 224.0.0.11 is reserved for all mobility agents. Which mean Foreign Agents or Home agents for Mobile IP. All the agent join this multicast group when it powers up in the network. Every router acts as “multicast routers” which in charge of forwarding packets to the modes that related to this multicast address. Multicast Routing enable Multicast address list Default Multicast address IPC_ALL_MOBILITY_AGENT_MULTICAST_ADDR Interface Multicast enabled 34 What are ad hoc parameters Hello interval:1 sec Allow hello loss = 3 Route Request rate 10 packets/sec 0.1 sec / request Retries: 5 Local repair TTL: The hop count# to the destination + Local add TTL (default 2) 35 WLAN interface parameters Beacon interval 0.02sec 11 Mbps Max failed polls : 2 PHY: Direct Sequence Spread Spectrum Chip Sequence: barker code XOR Robustness against interference MAC: DFWMAC PCF Point Coordination function F , DCF Distributed coordination function. CTS/RTS CSMA/CA– no hidden node problem INTER-FRAME SPACING AND BACKOFF TIME DFIS PIFS SIFS 36 Mobile IP parameters Agent: IRDP interval: 12-16 Hold time: 3x 16 = 48 Mobile nodes: Registration retries: 4 Registration interval: 4 37 What if the network partition? Trick: do not send out ad hoc beacons unless it registers with foreign agent. Even it received beacons, then the intersystem handover starts. However, the handover will fail due to no way to get to the gateway. Therefore it will still be using UMTS connections. 38 Gateway Discovery Repair 3 beacon missing from neighbour A neighbour A related to FA? No Yes Delete this route from RT Receive beacons from other nodes? Delete this route from RT and send out RERRs No Yes Local Repair Perform gateway discovery. Send out gateway query Mark this registration entry invalid in FA list Perform MANET-UMTS Handover 39 RFC or internet draft RFC 2002 IP Mobility Support 40 How packets being forward by gateway to MNs? MIP agent deliver packets to MNs through link-layer connectivity; however in ad hoc network, its multihop functionality need to use layer-3 identifier. On gateway, the ad hoc routing protocol must be used instead of MIP forwarding. 41 Delay – 2 mobile nodes 42 Delay – 5 mobile nodes 43 Why MANET-UMTS Handover doesn’t count Routing Area Update Complete It’s on SGSN side.!! We measured on MN side. Received Accepted and send out Complete is at almost the same time! 44 Ad hoc beacon Each node maintains its own timer for Beacon interval Back off random time algorithm Medium busy Only one beacon wins Adjust beacon interval with other nodes when received beacons. 45