Ad-Hoc Networking Course Instructor: Carlos Pomalaza-Ráez A Paper Presentation of ”Multihop Sensor Network Design for Wide-Band Communications” Proceedings of the IEEE, VOL.91, NO.8, August 2003 Terho Hautala

2 Outline Introduction New Cluster-Based Network AODV Mobility and handoff Ipv6-in-IPv4 Tunneling IEEE Measurements Conclusions

3 Introduction New cluster-based network architecture Mixture of two different types of network: Infrastructure (master-and-slave) Ad-hoc Slave Nodes (SN) are communicating via their respective Master Nodes (MNs) Base stations (MNs) are mobile (AODV routing) MNs act as a Home Agent (HA) and gateways for the cluster All nodes in a cluster typically move as a group If node changes cluster MIPv6 is deployed

4 Introduction Static addressingMobile IPMobile IP + Ad-hoc routing Ad-hoc Mobility Relatively fixed Increasing mobility Wired and wireless Wireless only Headquarters Airbase

5 Introduction Traditional cluster-based networking has difficulties when the number of nodes increases routing complexity network management large overheads In the paper a simple cluster networking is proposed. There WLAN is utilized. The goal is to provide a wide-band access for multimedia communication (video).

6 New Cluster-Based Network Ad-hoc channel Infrastructure channel AP LAN WLAN LAN AP Master node 4 (MN4) Master node 3 (MN3) AP LAN WLAN LAN AP Master node 2 (MN2) AP LAN WLAN Master Node 1 (MN1) Slave Node (SN) GW

7 AODV AODV is used to manage routes between Master Nodes. Instead of AODV DSR could also have been used, but it was not further investigated in the paper. AODV discovers routes by means of route request (RREQ) and route reply (RREP). Each node will reply to RREQ if it is either destination node or an intermediate node. In the case on link breakage error message (RERR) will be sent back to the source.

8 Mobility and handoff If SN moves to a new cluster mobile IPv6 (MIPv6) handoff is performed. SN will automatically configure link-local address and care-of-address (CoA) address based on the router advertisements. The home-agent is informed of the new CoA, so it can tunnel packets arriving to the home network (original cluster) to the new location. If SN receives a tunneled packet it should inform the source SN of the new location (route optimization).

9 Mobility and handoff AP LAN WLAN LAN AP LAN WLAN LAN AP (MN1)(MN3) (MN4) (MN2) Router Advertisement by IPv6 ROUTER SN automatically configures care-of-address (CoA) address based on the router advertisements BU SN sends Binding Update to inform Master Node 1 about the movement. Binding Cache is updated. BUs should also be sent to Correspondent Nodes (CNs) of SN BACK Master Node1 (HA for SN1) replies with Binding Acknowledgement and tunnels the packets to SN1

10 IPv6-in-IPv4 Tunneling IPv6 is used for operation in the infrastructure mode. The communication in the ad-hoc mode (between the master nodes) is based on IPv4 and AODV. If SN communicates with SN in another cluster, IPv6-in-IPv4 tunneling is used. Master node encapsulates the IPv6 packets received from SN and sends them to the master node of the destination cluster. The source address in IPv4 header is the address of the master node.

11 IPv6-in-IPv4 tunneling AP LAN WLAN AP LAN WLAN (MN1) (MN3) WLAN LAN AP (MN2) Data packets MN1 encapsulates the IPv6 packets received from SN1 IPv6 SN1 Packets are sent to the master node of the destination cluster. The source address in IPv4 header is the address of the master node.

12 IEEE IEEE supports direct sequence spread spectrum (DSSS) and frequency hopping spread spectrum (FHSS) modes. The DSSS mode is preferred if the number of clusters if small. If the number of clusters is large, FHSS can be more suitable. FHSS can select 79 possible hopping sequences to avoid inteference. IEEE is allowed several retransmission attempts (the number retransmission affects the performance)

13 Experimental setup Stationary, throughput and delay Retrans = 0 and retrans = 3 Bitrate = 128 / 384 / 768 kb/s

14 Experimental setup AP LAN WLAN AP LAN WLAN (MN1) (MN3) WLAN LAN AP (MN2) SN1

15 Scenarios (MN1) (MN2) WLAN LAN AP (MN3) AP LAN WLAN LAN AP SN-D 1-hop case: Same radio channel  resources are overwhelmed at higher bit rates SN-S 2 hops case: SN-S SN-D 3-hops case:

16 Results(throughput) Fig.1. Throughput performance for one node

17 Results(throughput) Fig.2. Throughput performance for two node

18 Results(delay) Fig.3. Propagation delay distributions for 1-hop communication (time resolution 10ms)

19 Results(delay) Fig.4. Propagation delay distributions for 2-hop communication (time resolution 10ms)

20 Results(delay) Fig.5. Propagation delay distributions for 3-hop communication (time resolution 10ms)

21 Results(delay) Fig.6. Average delay (time resolution 10ms)

22 AODV Route Change Scenario Cluster is moving (routes change), delay + tput Route change: 2-hop => 3-hop At low bitrate delay remains almost the same At high bitrate delay increases Route change a->b, duration about 2 sek

23 AODV route change scenario (MN2) (MN1) (MN3) 2-hops SN-S SN-D

24 (MN2) (MN1) (MN3) AODV route change scenario 3-hops SN-S SN-D

25 AODV route change results Fig.7. Delays in AODV route change

26 Mobile IP handoff scenario SN is moving (MIPv6 handover ja tunneling + BUs), delay + troughput Route A (original) Route B (BU has sent to HA and it is receiving packets from CN) Route C ( CN has received BU because SN sent it after receiving a tunneled packet) Handover delay remains same regardless the bitrate and max retries

27 (MN3) (MN1) (MN2) SN-D Mobile IP handoff scenario SN-S SN-D Route A: SN-S  MN-2  MN-1  SN-D Route B: SN-S  MN-2  MN-1   MN-2  MN-3  SN-D Route C: SN-S  MN-2  MN-3  SN-D HA CN

28 Mobile IP handoff scenario In he pa Fig.8. Average packet loss in Mobile IP

29 Mobile IP handoff scenario Fig.9. Delays in Mobile IP

30 Future work In he pa Use forward error correction (FEC) codes at the application layer Use Dynamic Source Routing (DSR) and Optimized Link State Routing (OLSR) Measure the network performance when a larger number of clusters have been utilized Develop robust error resilient coding for video streaming

31 Conclusions In he pa Assumption was that all the nodes within each cluster move as a group To allow handoffs for some isolated nodes Mobile IP has been considered AODV routing protocol has been used for ad-hoc routing Experimental testbed was developed for video based sensor network and was successfully tested

32 Thanks! In he pa