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					        Ad Hoc Wireless Networks




2002년 2학기       이동인터넷프로토콜          1
                     Agenda
•   Ad Hoc Network
•   Issues
•   Power Conservation Approaches
•   Routing Protocols
•   Energy Conservation at the Network Layer




2002년 2학기            이동인터넷프로토콜                 2
                 Ad hoc network
• A collection of two or more devices equipped with
  wireless communications and networking capability
  (Infrastructure-less Infrastructure)
• Every node can forward packets
• Self-organizing, adaptive
• IETF WG
    – MANET (Mobile Ad hoc Network)
        • http://www.ietf.org/html.charters/manet-
          charter.html


2002년 2학기               이동인터넷프로토콜                     3
                     Ad Hoc Network

            ad hoc network        Infrastructured network
                 ●                            ●
            ●                          ●
                 ●    ●                      ■    ●
                                             BS
            ●                         ●
                 ●                           ●



     이동단말기가 Router 역할 수행         유선으로 연결된 BS을 통하여 통신




2002년 2학기                    이동인터넷프로토콜                      4
2002년 2학기   이동인터넷프로토콜   5
                          Ad Hoc Network
• 3 Groups (G1, G2, G3)




A has data to send to H      A looks for a route to   A finds the route
                             H through G



2002년 2학기                      이동인터넷프로토콜                                  6
                 Ad Hoc Network
• Applications
    –   Conferencing
    –   Home Networking
    –   Emergency Services
    –   Personal Area Networks (PAN) and Bluetooth
    –   Embedded Computing Applications (PDA etc.)
    –   Sensor Networks



2002년 2학기               이동인터넷프로토콜                    7
                 Ad Hoc Network
• Issues
    –   Spectrum Allocation and Purchase
    –   Media Access
    –   Routing
    –   Multicasting
    –   Energy Efficiency
    –   TCP Performance
    –   Security & Privacy


2002년 2학기                이동인터넷프로토콜         8
 Protocol Layer Power Conservation
            Techniques

• Data-Link Layer
    – MAC (Media Access Control) – IEEE802.11
• Network Layer
    – Routing Protocol
• Transport Layer
    – TCP Performance



2002년 2학기                이동인터넷프로토콜              9
              Data-Link Layer
• Avoid unnecessary retransmissions
• Avoid collisions
• Put receiver in standby mode whenever possible
• Use/allocate contiguous slots for transmission and
  reception whenever possible
• Turn radio off (sleep) when not transmitting or
  receiving


2002년 2학기           이동인터넷프로토콜                      10
                Network Layer
•   Consider route relaying load
•   Consider battery life in route selection
•   Reduce frequency of sending control message
•   Optimize size of control headers
•   Efficient route reconfiguration techniques




2002년 2학기            이동인터넷프로토콜                    11
              Transport Layer
• Avoid repeated retransmissions
• Handle packet loss in a localized manner
• Use power-efficient error control schemes




2002년 2학기           이동인터넷프로토콜                 12
                           Routing
• New routing protocols for Ad Hoc networks are
  needed
    – OSPF
        • Link-state protocol
        • High bandwidth required to maintain a current view of the
          network
    – RIP
        • Distance-vector algorithm
        • Very slow convergence (count to infinity)


2002년 2학기                  이동인터넷프로토콜                                  13
            Ad Hoc Routing Protocols
                               AD-HOC MOBILE
                             ROUTING PROTOCOLS




             TABLE DRIVEN/                  ON-DEMAND-DRIVEN/
              PROACTIVE                         REACTIVE



                                  HYBRID

                                                  DSR ABR
            DSDV WRP

                                    ZRP          TORA AODV
            CGSR STAR
                                                 CBRP RDMAR



2002년 2학기                       이동인터넷프로토콜                       14
                Routing Protocols
• Proactive (Table driven)
    – DSDV (Destination Sequenced Distance vector)
    – WRP (Wireless Routing Protocol)
    – CSGR (Cluster Switch Gateway Routing)
• Reactive (On-demand-driven)
    – AODV (Ad Hoc On-Demand Distance Vector Routing) : RREQ,
      RREP
    – DSR (Dynamic Source Routing) – use cache
    – SSR (Signal Stability Routing)
    – PAR (Power-Aware Routing)
    – ABR (Associativity-Based Long Lived Routing)
• Hybrid
    – ZRP (Zone Routing Protocol)
2002년 2학기                이동인터넷프로토콜                          15
                           DSDV
• Destination Sequenced Distance Vector
    – Charles E. Perkins
•   Table-driven
•   Based on Bellman-Ford routing algo.
•   Full dump & incremental packet
•   Too many overhead for Ad hoc



2002년 2학기              이동인터넷프로토콜          16
                        AODV
• Ad Hoc On-Demand Distance Vector Routing
    – Charles E. Perkins, Elizabeth M. Royer
• Improvement on DSDV
• RREQ, RREP
• Support only bidirectioinal link




2002년 2학기              이동인터넷프로토콜               17
                          AODV

                     N2
                               N5
                                           N8   Destination

      Source   N1
                          N4
                                      N7


                    N3
                               N6




2002년 2학기                 이동인터넷프로토콜                           18
                               AODV

                          N2
      RREQ Broadcast                  N5
                                                         N8    Destination

      Source   N1
                               N4
                                                 N7


                        N3                   Each node adds previous node
                                      N6     to its routing table (to
                                             establish a reverse path)

                       Propagation of the RREQ


2002년 2학기                      이동인터넷프로토콜                                     19
                               AODV

                         N2
               RREQ
                                      N5
                                                       N8   Destination

      Source   N1
                              N4
                                                 N7


                       N3
                                      N6


                      Path of the RREP to the source


2002년 2학기                     이동인터넷프로토콜                                   20
                               AODV

                       N2
               Data
                                      N5
                                                N8   Destination

      Source   N1
                               N4
                                           N7


                      N3
                                      N6


                           Sending Data


2002년 2학기                     이동인터넷프로토콜                            21
                              DSR
• Dynamic Source Routing
    – David B. Johnson (Carnegie-Mellon Univ.)
• Two major phase
    – Route discovery
        • On cache misses
    – Route maintenance
        • Use cache -> Router Error packet (passive ack)
• Support unidirectioinal links

2002년 2학기                   이동인터넷프로토콜                      22
                               DSR

                     N2
                                N5
                                           N8   Destination

      Source   N1
                          N4
                                      N7


                    N3
                                N6




2002년 2학기                 이동인터넷프로토콜                           23
                                       DSR

                            N2     N1-N2

                                                      N1-N2-N5
                    N1                       N5
                                                                      N8    Destination
                               N1-N3-N4

      Source   N1                          N1-N3-N4                 N1-N3-N4-N7
                                  N4
                          N1-N3                           N7
                N1                N1-N3-N4
                                                      N1-N3-N4-N6
                          N3
                                             N6


                         Propagation of the RREQ


2002년 2학기                         이동인터넷프로토콜                                               24
                                     DSR

                                N1-N2-N5-N8
                           N2
            N1-N2-N5-N8                        N1-N2-N5-N8
                                         N5
                                                             N8   Destination

      Source    N1
                                N4
                                                   N7


                          N3
                                         N6


               Propagation of the route reply with the route record


2002년 2학기                       이동인터넷프로토콜                                       25
                                    DSR

                          N2
               Data
                                      N5
                                                         N8   Destination

      Source   N1
                               N4
                                                N7


                        N3
                                      N6


                      Sending Data (by Source Routing)


2002년 2학기                      이동인터넷프로토콜                                    26
                           ABR
• Associativity-Based Long Lived Routing
    – C-K Toh
• Consider
    –   Associativity Ticks/Counts
    –   Link Delay
    –   Signal Strength
    –   Power Life
    –   Route Relay Load


2002년 2학기                이동인터넷프로토콜         27
                              ZRP
• Zone Routing Protocol
    – Haas, Pearlman (Cornell University)
• Proactive + Reactive
    – Intrazone (Routing Zone) - Proactive
        • IARP(Intrazone Routing protocol)
    – Interzone - Reactive

        • BRP(Bordercast Routing protocol)
        • IERP(Interzone Routing Protocol)

2002년 2학기                    이동인터넷프로토콜       28
            Energy conservation

                 Ad Hoc routing




2002년 2학기         이동인터넷프로토콜       29
    Geography-informed Energy
  Conservation for Ad Hoc Routing

            Ya Xu, John Heidemann, Deborah Estrin
                  ACM/IEEE Mobicom2001




2002년 2학기             이동인터넷프로토콜                     30
                       Abstract
• GAF
    – Geographical Adaptive Fidelity
• Use application- and system-level info.
• Independent of underlying ad hoc routing protocol
  (DSR, AODV)




2002년 2학기              이동인터넷프로토콜                  31
                   Introduction
• Energy dissipation in idle state cannot be ignored
• Routing fidelity
    – Uninterrupted connectivity between communication
      nodes
• Employ location info (from GPS, etc.)




2002년 2학기              이동인터넷프로토콜                         32
                    Introduction

                       2


            1                         4


                        3                 5


            1
                Nominal radio range
2002년 2학기                  이동인터넷프로토콜          33
            Energy-conserving routing
• Virtual grid
    – All nodes in a particular grid square are equivalent with
      respect to forwarding packets
    – For two adjacent grids A and B, all nodes in A can
      communicate with al nodes in B and vice versa
    – Based on the nominal radio range R




2002년 2학기                이동인터넷프로토콜                            34
     Determining node equivalence

                A   2             B        C


            1                   4

                        3                  5
            r               r          r

                r 2  ( 2r ) 2  R 2
                           R
                        r
                            5
2002년 2학기           이동인터넷프로토콜                  35
              GAF State Transition
• Three states
    – Sleeping (Ts)
    – Discovery (Td)
        • Discovery message
            – node id, grid id, enat(estimated node active time)
    – Active (Ta)
        • Periodically re-broadcast its discovery msg at intervals Td




2002년 2학기                   이동인터넷프로토콜                                   36
              GAF State Transition


               sleeping
                       receive
                       discovery msg
            after Ts   from high rank
                       nodes
                                                   active
                             after Td

                                        after Ta
              discovery



2002년 2학기                  이동인터넷프로토콜                        37
                       Tuning GAF
• enat (estimated node active time)
    – enlt/2
        • enlt : time to use up all remaining energy
• Td (discovery message interval)
    – A uniform random value between 0 and some constant
• Ta
    – enat
• Ts
    – Uniformly in [enat/2, enat]

2002년 2학기                   이동인터넷프로토콜                      38
                     Tuning GAF
• Node Ranking
    – Accorting to remaining energy level…
    1. A node in active state has higher rank than a node in
       discovery state
    2. For nodes with same state, GAF gives nodes with
       longer enat higher rank




2002년 2학기                이동인터넷프로토콜                             39
            Adapting to high mobility
• engt (expected node grid time)
    – In the discovery message
    – Ts < engt
    – engt = r/s
        • s : current speed of a node
• GAF-b (basic)
• GAF-ma (mobility adaption)


2002년 2학기                   이동인터넷프로토콜   40
                          Simulation
• 50 mobile nodes
    – random waypoint model by Johnson, CMU
    – Speed : 0~1 m/s, 0~20 m/s
    – Nominal range : 250m
• Area
    – 1500m x 300m
• Pause times (0~900ms)
• Traffic
    – CBR UDP
    – 1, 10, 20 pkts/sec by 10 traffic nodes

2002년 2학기                    이동인터넷프로토콜         41
                          Simulation
• Energy Model
    – AT&T 2Mb/s WaveLAN
        •   1.6W for transmit
        •   1.2W for receiving
        •   1.0W for listening
        •   0.025W for sleeping




2002년 2학기                   이동인터넷프로토콜   42
                           Simulation



                                                 In case of AODV,
                                                 all nodes die out
                                                  around 450ms!!




Network lifetime comparisons : GAF-b vs. AODV at low
node speed (1m/s) under various pause time.
Movement : 1m/s, traffic : 20 pkts/s
    2002년 2학기                    이동인터넷프로토콜                           43
            Simulation




2002년 2학기    이동인터넷프로토콜   44
2002년 2학기   이동인터넷프로토콜   45
   BECT: A Balanced Energy Consumption Algorithm
   by Threshold-Tuning for Mobile Ad Hoc Networks


                   2002. 11. 1
             Real Time Internet Lab.
                    Jaeho Chang




2002년 2학기          이동인터넷프로토콜                  46
                      Agenda
• DSR
    – Dynamic Routing Protocol
• BECT
    – DSR modification
    – Energy-Balancing by Threshold Tuning
• Simulation
• Conclusion & Future Work


2002년 2학기             이동인터넷프로토콜              47
                               DSR
• Dynamic Source Routing
    – Monarch Project (CMU)
        • http://www.monarch.cs.rice.edu
    – On-demand wireless Ad Hoc routing protocol
    – Source routing
    – Promiscuous mode (overhear), cache
• Two major phase
    – Route discovery
        • RREQ, RREP msg
    – Route maintenance
        • On receiving RERR msg -> cache -> Route Discovery

2002년 2학기                   이동인터넷프로토콜                         48
                                       DSR

                            N2     N1-N2

                                                      N1-N2-N5
                    N1                       N5
                                                                      N8    Destination
                               N1-N3-N4

      Source   N1                          N1-N3-N4                 N1-N3-N4-N7
                                  N4
                          N1-N3                           N7
                N1                N1-N3-N4
                                                      N1-N3-N4-N6
                          N3
                                             N6


                         Propagation of the RREQ


2002년 2학기                         이동인터넷프로토콜                                               49
                                     DSR

                                N1-N2-N5-N8
                           N2
            N1-N2-N5-N8                        N1-N2-N5-N8
                                         N5
                                                             N8   Destination

      Source    N1
                                N4
                                                   N7


                          N3
                                         N6


               Propagation of the route reply with the route record


2002년 2학기                       이동인터넷프로토콜                                       50
                               DSR

                     N2
                                N5
                                           N8   Destination

      Source   N1
                          N4
                                      N7


                    N3
                                N6




2002년 2학기                 이동인터넷프로토콜                           51
                                DSR

                           N4         N5




        Source   N1              N3             N2   Destination




                      N6                   N8
                                 N7




2002년 2학기                   이동인터넷프로토콜                              52
                           BECT
• BECT
    – Energy-Balancing by Threshold Tuning
    – Two phases
        • Route Discovery by Threshold
        • Route Change by Threshold




2002년 2학기                 이동인터넷프로토콜          53
                                      BECT

                            N2
               RREQ (th)
                                            N5
                                                      N8   Destination

      Source      N1
                                    N4
                                                 N7
            RREQ (th)
                                RREQ (th)

                           N3
                                            N6




2002년 2학기                           이동인터넷프로토콜                            54
            BECT (Route Discovery)

                       N2
                                 N5
                                             N8   Destination

      Source    N1
                            N4
                                        N7
               Data

                      N3
                                 N6




2002년 2학기                   이동인터넷프로토콜                           55
                    Basic Operation 1

                                N4            N5




      Source (th)   N1                   N3               N2   Destination
                             RREQ (th)




                           N6                        N8
                                         N7


                         Route Change by Threshold

2002년 2학기                         이동인터넷프로토콜                                  56
                    Basic Operation 2

                               N4         N5




      Source (th) N1                 N3             N2   Destination
        N1-N3-N5              RREP
        N1-N4-N5-N2
        N1-N6-N7-N8-N2


                         N6                    N8
                                     N7




2002년 2학기                        이동인터넷프로토콜                             57
                    Basic Operation 3

                              N4           N5




      Source (th) N1                  N3             N2   Destination
        N1-N3-N5          Data (th)
        N1-N4-N5-N2
        N1-N6-N7-N8-N2


                         N6                     N8
                                      N7




2002년 2학기                      이동인터넷프로토콜                                58
                    Basic Operation 4

                                  N4        N5
                 Data (th)



      Source (th) N1                   N3             N2   Destination
        N1-N3-N5
        N1-N4-N5-N2
        N1-N6-N7-N8-N2


                             N6                  N8
                                       N7




2002년 2학기                          이동인터넷프로토콜                             59
                    Basic Operation 5

                              N4          N5




      Source (th) N1                 N3             N2   Destination
        N1-N3-N5
        N1-N4-N5-N2      data (th)
        N1-N6-N7-N8-N2


                         N6                    N8
                                     N7




2002년 2학기                       이동인터넷프로토콜                              60
                    Basic Operation 6

                              N4        N5




      Source (th) N1               N3             N2   Destination
        N1-N3-N5
        N1-N4-N5-N2
        N1-N6-N7-N8-N2


                         N6                  N8
                                   N7




2002년 2학기                      이동인터넷프로토콜                             61
                    Basic Operation 7

                              N4            N5




    Source (th-c)   N1                 N3             N2   Destination
                         RREQ (th-c)




                         N6                      N8
                                       N7




2002년 2학기                       이동인터넷프로토콜                                62
                    Basic Operation 8

                               N4         N5




    Source (th-c)   N1               N3             N2   Destination
        N1-N3-N5              RREP
        N1-N4-N5-N2
        N1-N6-N7-N8-N2


                         N6                    N8
                                     N7




2002년 2학기                        이동인터넷프로토콜                             63
                    Basic Operation 9

                              N4            N5




    Source (th-c)   N1                 N3             N2   Destination
        N1-N3-N5         Data (th-c)
        N1-N4-N5-N2
        N1-N6-N7-N8-N2


                         N6                      N8
                                       N7




2002년 2학기                      이동인터넷프로토콜                                 64
                  BECT Algorithm

• Addition to DSR
    – Node
        • EnergyThreshold
        • EnergySelf = INIT_ENERGY – EnergyComsumed
    – Packet Headers
        • EnergyThreshold
            – data, rreq, rrep, rerr packet




2002년 2학기                   이동인터넷프로토콜                 65
                  BECT Algorithm

  • Threshold Tuning
      – 보내는 모든 packet에 자신의 Th추가
      – 수신 또는 overhear하는 모든 packet
            • Packet th < 자신의 th 이면 자신의 th tuning
  • Route Discovery
      – RREQ시 자신의 th 삽입
            • 중간 노드에서 RREQ수신시 packet th > 자기 E 이면 drop
      – SRC에서 RREP 못받으면 th낮추어 다시 RREQ
            • THRESHOLD_RESOLUTION

2002년 2학기                 이동인터넷프로토콜                  66
                     BECT Algorithm

 • 중간노드 Data전송
     – Data packet의 th > 자신의 E 이면, drop없이 RERR
            • Packet th > E – (Th_resolution*0.2)이면 RRER


      Source    N1         N2          N3        N4     Destination



                                  N6               N8
                         N5
                                            N7



2002년 2학기                     이동인터넷프로토콜                               67
       BECT Algorithm (Summary)
            Node                                              Action

            Source    When initiating a RREQ;
                       Set ethp to ethn;
                      When a RREQ timeout;
                       ethn -= eth_dec;
                       Initiate a new RREQ;
                      When receiving or overhearing packets;
                            If ethn > ethp, then set ethn to ethp;


       Intermediate   When receiving a RREQ;
                       If rel < ethp, then drop the RREQ;
                      When forwarding a data packet;
                       If ethp > (rel – eth_dec / m), then initiate a RERR;
                      When receiving or overhearing packets;
                            If ethn > ethp, then set ethn to ethp;


        Destination   When receiving or overhearing packets;
                          If ethn > ethp, then set ethn to ethp;
2002년 2학기                          이동인터넷프로토콜                                  68
                           Simulation

                           N4        N5




        Source   N1             N3             N2   Destination




                      N6                  N8
                                N7




2002년 2학기                   이동인터넷프로토콜                             69
          Simulation (Simple Topology)

                                                     Path

                                            N1-N6-N7-N8-N2


                                              N1-N4-N5-N2
              N4        N5
                                                                                          DSR
                                                 N1-N3-N2


                                                             t1       t2   t3   t4   t5    t6         t
  N1               N3             N2                 Path

Source                        Destination   N1-N6-N7-N8-N2
                                                                  t                             BECT
                                              N1-N4-N5-N2

         N6        N7        N8
                                                 N1-N3-N2


                                                             t1       t2   t3   t4   t5    t6     t




2002년 2학기                               이동인터넷프로토콜                                                         70
              Simulation (GloMoSim)
•   SIMULATION-TIME 900S
•   TERRAIN-DIMENSIONS (1000, 1000)
•   NUMBER-OF-NODES 50
•   NODE-PLACEMENT    UNIFORM/RANDOM
•   ROUTING-PROTOCOL DSR/BECT
•   Traffic
    –   cbr
    –   10 /20 sources
    –   Packet size : 128/512/1024 Bytes
    –   Packet Interval : 5 packets/s
•   Movement
    – Random-waypoint
         • pause time : 0/100/300/600/900 sec
         • speed : min 0, max 1 m/s


2002년 2학기                          이동인터넷프로토콜    71
                           Simulation
• Energy Model
    – Lucent 2Mb/s WaveLAN 802.11 cards.
        •   1.4W for transmit
        •   1.0W for receiving
        •   0.83W for listening/idle
        •   0.043W for sleeping




2002년 2학기                     이동인터넷프로토콜    72
                                         Simulation (Avg Consumed Energy)


                             2.650                                                                        5.050
Energy Consumption (mWhr)




                                                                              Energy Consumption (mWhr)
                             2.600                                                                        5.000
                             2.550                                                                        4.950
                             2.500                                                                        4.900
                             2.450                                                                        4.850
                             2.400                                                                        4.800
                             2.350                             D SR                                                                       D SR
                                                                                                          4.750
                                                               B EC T (1)                                                                 B EC T (1)
                             2.300                                                                        4.700
                                                               B EC T (0.2)                                                               B EC T (0.2)
                             2.250                                                                        4.650
                                     0    100       300       600      900                                        0   100       300       600      900

                                                       i
                                                pause t m e                                                                        i
                                                                                                                            pause t m e


                                                10 src                                                                      20src

                            2002년 2학기                                 이동인터넷프로토콜                                                                          73
                                        Simulation (Standard Deviation)


                            3.500                                                                       4.000




                                                                            Standard Deviation (mWhr)
Standard Deviation (mWhr)




                                                                                                        3.500
                            3.000
                                                                                                        3.000
                            2.500
                                                                                                        2.500
                            2.000
                                                                                                        2.000
                            1.500
                                                                                                        1.500
                            1.000                            D SR                                                                        D SR
                                                                                                        1.000
                                                             B EC T (1)                                                                  B EC T (1)
                            0.500                                                                       0.500
                                                             B EC T (0.2)                                                                B EC T (0.2)
                            0.000                                                                       0.000
                                    0   100      300        600      900                                        0   100      300        600     900

                                              pause t m e
                                                     i                                                                           i
                                                                                                                          pause t m e



                                              10 src                                                                      20src

                 2002년 2학기                                           이동인터넷프로토콜                                                                     74
                                     Simulation (Data Delivery Fraction)


                         1.000                                                                     0.980




                                                                          Data Delivery Fraction
Data Delivery Fraction




                         0.990
                                                                                                   0.975
                         0.980

                         0.970                                                                     0.970

                         0.960
                                                           D SR                                    0.965         D SR
                         0.950                             B EC T (1)                                            B EC T (1)
                                                           B EC T (0.2)                                          B EC T (0.2)
                         0.940                                                                     0.960
                                 0    100      300        600     900                                      0   100       300       600   900

                                                   i
                                            pause t m e                                                                     i
                                                                                                                     pause t m e


                                            10 src                                                                     20src

           2002년 2학기                                               이동인터넷프로토콜                                                                   75
                           Simulation (Control Overhead Fraction)


                   0.060                                                              0.040
                                                                                      0.035
                   0.050
Control Overhead




                                                                   Control Overhead
                                                                                      0.030
                   0.040
                                                                                      0.025
                   0.030                                                              0.020
                                                                                      0.015
                   0.020                            D SR
                                                                                      0.010                            D SR
                   0.010                            B EC T (1)                                                         B EC T (1)
                                                    B EC T (0.2)                      0.005
                                                                                                                       B EC T (0.2)
                   0.000                                                              0.000
                           0   100      300        600      900                               0   100      300        600      900

                                            i
                                     pause t m e                                                               i
                                                                                                        pause t m e



                                     10 src                                                             20src

  2002년 2학기                                                 이동인터넷프로토콜                                                                 76

				
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