Department of Information Engineering University of Padova, Italy COST273 May 30-31, 2002 Helsinki TD (02)-062 A note on the use of these ppt slides: We’re making these slides freely available to all, hoping they might be of use for researchers and/or students. They’re in PowerPoint form so you can add, modify, and delete slides (including this one) and slide content to suit your needs. In return for use, we only ask the following: If you use these slides (e.g., in a class, presentations, talks and so on) in substantially unaltered form, that you mention their source. If you post any slides in substantially unaltered form on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and put a link to the authors webpage: Thanks and enjoy!

On the performance of AODV and FSR routing algorithms on Bluetooth scatternets: preliminary results Department of Information Engineering University of Padova, Italy Andrea Zanella COST273 May 30-31, 2002 Helsinki TD (02)-062

May 30-31, 2002COST273 TD(02)-0623 Outline of the contents Bluetooth basic Ad-hoc routing algorithms  Ad-hoc On demand Distance Vector (AODV)‏  Fisheye State Routing (FSR)‏ Simulation model Experimental results Conclusions and future work

May 30-31, 2002COST273 TD(02)-0624 Bluetooth Technology What is Bluetooth?  A wireless technology Proposed as cable replacement for leakage portable electronic devices, BT provides short-range low-power point-to-(multi)point wireless connectivity  A global industry standard in the making Initially developed by Ericsson, now BT is promoted by an industry alliance called Special Interest Group (SIG)‏

May 30-31, 2002COST273 TD(02)-0625 Bluetooth piconet Two up to eight Bluetooth units sharing the same channel form a piconet In each piconet, a unit acts as master, the others act as slaves Channel access is based on a centralized polling scheme active slave master parked slave standby slave1 slave2 slave3 master

May 30-31, 2002COST273 TD(02)-0626 FH & TDD Each piconet is associated to frequency hopping (FH) channel  The pseudo-random FH sequence is imposed by the master  Time is divided into consecutive time-slots of 625  s  Each slot corresponds to a different hop frequency Full-duplex is supported by Time-division-duplex (TDD)  Master-to-slave (downlink) transmissions start on odd slots  Slave-to-Master (uplink) transmissions start on even slots 625  s t t master slave f(2k)‏f(2k+1)‏f(2k+2)‏

May 30-31, 2002COST273 TD(02)-0627 Bluetooth scatternets Piconets can be interconnected by Inter-piconet Units (IPUs)‏ IPUs may act as gateways, forwarding traffic among adjacent piconets IPUs must time-division their presence among the piconets Time division can be realized by using SNIFF mode

May 30-31, 2002COST273 TD(02)-0628 Next in the line… Bluetooth basic Ad-hoc routing algorithms  Ad-hoc On demand Distance Vector (AODV)‏  Fisheye State Routing (FSR)‏ Simulation model Experimental results Conclusions and future work

May 30-31, 2002COST273 TD(02)-0629 Motivations of the work Bluetooth gets out typical MANET scenario  Physical proximity does not imply connection  Connection set-up may take infinite time  Broadcast is supported only within piconets Hence, MANET algorithms have to be tested in Bluetooth environment  Table-driven algorithms: LSR, DSDV,WRP,FSR  On demand algorithms: DSR,TORA,AODV?

May 30-31, 2002COST273 TD(02) IP-layer routing Routing is performed at IP layer, making use of IP addresses Pros  No address-mapping  Independence of the network details Cons  Each node must support IP functionalities  IP datagrams must be reassembled before forwarding Access Code Access Code Layer 2 Header Layer 2 Payload SCIDDCID L2CAP Payload Source IP Address Destination IP Address IP Payload

May 30-31, 2002COST273 TD(02) AODV Algorithm (1)‏ Route discovery  Broadcast Route Request packet (RREQ), containing source and destination IP addresses Intermediate nodes that receive the RREq for the first time  Increment by one the hop count field in the packet  Add an entry containing: source IP, destination IP, predecessor IP  Broadcast the RREQ packet Source node IP1 Destination node IP7 IP2 IP3 IP4 IP5 IP6 1IP1 IP7 1IP1 IP7 2IP2IP1IP7 3IP4IP1IP7 3IP4IP1IP7 4IP5IP7IP1

May 30-31, 2002COST273 TD(02) AODV Algorithm (2)‏ Destination responds to the RREQ by unicasting a Route Reply (RREP) packet to the source The RREP flows backward along the path traced by the RREQ Intermediate nodes that process the RREP update their entry Entries that are not updated expire after a given timeout 1IP1 IP7 1IP1 IP72IP2IP1IP7 3IP4IP1IP7 3IP4IP1IP7 4IP5IP1IP7 Source node IP1 IP7 Destination node IP2 IP3 IP4 IP5 IP6 4IP2IP7IP1 1IP7 IP1 3 3IP7 IP1 3 2IP7 IP1 2

May 30-31, 2002COST273 TD(02) AODV Algorithm (3)‏ In case of link failure, AODV propagates a Route Error (RERR) message to the upstream nodes Receiving an RERR, nodes set to infinity the distance to the destination If the path is still needed, nodes start a new path discovery procedure Source node IP1 IP7 Destination node IP2 IP3 IP4 IP5 1IP1 IP72IP2IP1IP7 3IP4IP1IP7 4IP5IP1IP7 4IP2IP7IP1 1IP7 IP1 3 3IP7 IP1 3 2IP7 IP1 2 X X X X X X X X

May 30-31, 2002COST273 TD(02) FSR Algorithm (1)‏ Each node maintains link state information for every other node FSR generates route update on a periodic basis Routing information is propagated to neighbours only Updates occur on the basis of the Fisheye algorithm:  Nodes are divided in scopes, on the basis of their distance to the source  Routing information for a given destination is updated with a frequency that is inversely proportional to the scope of the destination

May 30-31, 2002COST273 TD(02) FSR Algorithm (2)‏ Fisheye scope= set of nodes within a given number of hops Closer nodes are update more frequently than farther ones 3 or more hops 2 hop 1 hop Reference node

May 30-31, 2002COST273 TD(02) FSR Algorithm (3)‏ Getting close to the destination, the routing information becomes progressively more accurate 0:{1}2 1:{0,2,3}1 2:{5,1,4}2 3:{1,4}0 4:{5,2,3}1 5:{2,4}2 0:{1}2 1:{0,2,3}1 2:{5,1,4}2 3:{1,4}0 4:{5,2,3}1 5:{2,4}2 TT Hop TT Hop 0:{1}2 1:{0,2,3}2 2:{5,1,4}1 3:{1,4}1 4:{5,2,3}0 5:{2,4}1 0:{1}2 1:{0,2,3}2 2:{5,1,4}1 3:{1,4}1 4:{5,2,3}0 5:{2,4}1 TT Hop TT Hop 0:{1}1 1:{0,2,3}0 2:{5,1,4}1 3:{1,4}1 4:{5,2,3}2 5:{2,4}2 0:{1}1 1:{0,2,3}0 2:{5,1,4}1 3:{1,4}1 4:{5,2,3}2 5:{2,4}2 TT Hop TT Hop

May 30-31, 2002COST273 TD(02) Next in the line… Bluetooth basic Ad-hoc routing algorithms  Ad-hoc On demand Distance Vector (AODV)‏  Fisheye State Routing (FSR)‏ Simulation model Experimental results Conclusions and future work

May 30-31, 2002COST273 TD(02) Simulation platform Simulator Tool: OPNET Modeler Ver. 8.0 The simulator does support  Baseband protocols Frequency Hopping, Paging, Inquiry, Scan  Link manager (LM) protocol  Link layer control and adaptation protocol (L2CAP) Connection setup/release, Sniff Mode The simulator does not support  Handover for Bluetooth units  Multi-slot data packets

May 30-31, 2002COST273 TD(02) Model assumptions Pre-formed Scatternet  Roles of master/slave/gateway are preassigned Pure Round Robin polling strategy  Nodes in a piconet have the same priority and get polled in cyclic order 2 piconets per IPU  IPU divides it time equally between the piconets by means of the sniff mechanism  IPUs are not coordinated Network layer routing algorithms: AODV & FSR

May 30-31, 2002COST273 TD(02) Scatternet topology

May 30-31, 2002COST273 TD(02) Next in the line… Bluetooth basic Ad-hoc routing algorithms  Ad-hoc On demand Distance Vector (AODV)‏  Fisheye State Routing (FSR)‏ Simulation model Experimental results Conclusions and future work

May 30-31, 2002COST273 TD(02) Average end-to-end delay (1)‏ Simulation parameters  CBR traffic: 20 kbit/sec  5 hops connection  2 gateway units (IPUs)‏ Results  End-to-end delay grows almost linearly with the Sniff period  Short IP datagrams better exploit the pipeline effect

May 30-31, 2002COST273 TD(02) Average end-to-end delay (2)‏ Simulation parameters  Sniff period: 100 slots  5 hops connection Results  Short IP dtgs achieve lower end-to-end delay but saturate earlier  Long IP dtgs incur in higher end-to-end delay but increase capacity utilization

May 30-31, 2002COST273 TD(02) AODV: route discovery delay (1)‏ Simulation parameters  Sniff period: 100 slots  Route length increasing Results  Using Link Layer (AODV-LL) messages to refresh table entries the discovery time is shorter Path discovery query ends one hop earlier  Route discovery delay grows almost linearly with the distance of the destination

May 30-31, 2002COST273 TD(02) AODV: route discovery delay (2)‏ Simulation parameters  Sniff period ranges from 50 to 200 slots  5 hops connection Results  Route discovery delay grows almost linearly with the Sniff period  AODV-LL shows much better performance than AODV-std Impact of Sniff period is higher on longer path

May 30-31, 2002COST273 TD(02) Fisheye: control traffic Simulation parameters  Sniff time: 50 slots  Different Refresh periods  Different number of scopes Remark: # Scope=0 is the Global State Routing Results  As expected, the more the number of scopes the less the control traffic  Refresh Times less than 0.1s absorb more than 10% of the system capacity  Refresh time must be longer than 0.1s, but this increases the route updating delay

May 30-31, 2002COST273 TD(02) Fisheye: update delay (1)‏ Simulation parameters  5 hops connection  2 scopes  Sniff period: 50 slots  Refresh period ranges from 0.1 to 0.25 s Results  A refresh period of 0.1 s updates nodes 6-hop faraway from the source within 1 s

May 30-31, 2002COST273 TD(02) Fisheye: update delay (2)‏ Simulation parameters  2 scopes  Sniff perriod ranges from 50 to 300 slots  Refresh period:0.25 s  Path length increasing Results  Update delay mainly due to the path length  Sniff period has smaller impact

May 30-31, 2002COST273 TD(02) Next in the line… Bluetooth basic Ad-hoc routing algorithms  Ad-hoc On demand Distance Vector (AODV)‏  Fisheye State Routing (FSR)‏ Simulation model Experimental results Conclusions and future work

May 30-31, 2002COST273 TD(02) Final Remarks Datagram size and Sniff period have a considerable impact on IP end-to-end delay and AODV route discovery time FSR refresh time must be carefully chosen AODV appears suitable in case of  Sparse connections  Relaxed latency constraints  Semi-static topology FSR appears more convenient for  Dense connections  Dynamic and wide topology

May 30-31, 2002COST273 TD(02) Future work Coming Soon (maybe…)‏  Mathematical analysis of the scatternet efficiency  Simulator enhancements Multi-slot packets Handover  Comparison with Link Layer Routing algorithms  Implementation of dynamic scatternet formation algorithms

May 30-31, 2002COST273 TD(02) Spare slides…

May 30-31, 2002COST273 TD(02) Table-Driven algorithms Each node maintains one or more tables with routing information for every other node Nodes periodically exchange tables information Algorithms differ for the number of routing- related tables and updating strategy Examples  Fisheye State Routing (FSR)  Hierarchical State Routing (HSR)‏  Wireless Routing Protocol (WRP)‏

May 30-31, 2002COST273 TD(02) On Demand algorithms Nodes maintain route information only to the nodes for which there is an actual need Routes are built on a demand basis, by means of a route discovery mechanism Changes on the network topology are propagated only to the interested nodes Examples  Ad hoc On demand Distance Vector (AODV)‏  Cluster Based Routing (CBR)‏  Dynamic Source Routing (DSR)  Associativity Based Routing (ABR)‏

May 30-31, 2002COST273 TD(02) Routing on Bluetooth scatternet Bluetooth baseband packets contain AMA_ADDR  Temporary and local meaning only Routing must be performed above the baseband layer! Possible approaches  Data Link Layer: Routing performed between L2CAP and IP Routing Vector Method (RVM)‏ Bluetooth Network Encapsulation Protocol (BNEP)‏  Network Layer: routing performed at IP layer MANET algorithms

May 30-31, 2002COST273 TD(02) Data Link layer routing RVM lies above L2CAP and beneath IP It uses 3 bit local IDs to identify the piconets Routing is performed by means of the routing vector mechanism Pros: simplicity, bandwidth conservation, low resources requirement Cons: Topological changes determine address re-map Access Code Layer 2 Header Layer 2 Payload FFDABFRVF Layer 3 Payload Layer 3 Header Layer 3 Payload