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Symmetric Detection

Symmetric Detection. Overview. In this phase, each mote will maintain a neighbor table. It provide a command bool isSymmetric( u int16_t neighborID) for the backbone creation phase . The judgment is based on the statistic. Overview. Provides interface SDNeighborTable StdControl

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Symmetric Detection

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  1. Symmetric Detection

  2. Overview • In this phase, each mote will maintain a neighbor table. • It provide a command boolisSymmetric(uint16_t neighborID)for the backbone creation phase . • The judgment is based on the statistic.

  3. Overview • Provides interface • SDNeighborTable • StdControl • Used components • SDM • RoutingC • RandomLFSR • TimerC • TinyAlloc

  4. Data Structure 2 1 18 Every neighborID occupies 2 bytes, so one packet can accommodate 18/2=9 neighborID MAX_NEIGHBOR = 40 Totally we need 5 packets at most. MAX_SD_BUFFER_SIZE = (MAX_NEIGHBOR+5)/10, Shall we use MAX_NEIGHBOR/9+1? Or shall we change the SD_PAYLOAD_SIZE = 18 ?

  5. Data Structure typedef struct{ uint16_t neighborID[MAX_NEIGHBOR]; uint8_t symmChannel[MAX_NEIGHBOR]; uint8_t asymmChannel[MAX_NEIGHBOR]; uint8_t noChannel[MAX_NEIGHBOR]; uint8_t currStatus[MAX_NEIGHBOR]; /* 0------noChannel 1------asymmChannel 2------symmeChannel */ uint8_t aliveLastTime[MAX_NEIGHBOR]; } NEIGHBOR_TABLE; Note: neighborID[0..MAX_NEIGHBOR] is initialed to be 0xffff

  6. Workflow Check Neighbor table Check Neighbor table Scan the neighbor table Generate packets to be send Start a new Timer Send Packet Interval of T1:SEND_BEACON_PERIODInterval of T2:(Random.rand()) % (SEND_BEACON_PERIOD/global_size)

  7. Workflow • How about the last packet in the T1 interval • If the process to generate packets is too long or due to other delay, then the last packet will be lost. • Guarantee that SEND_BEACON_PERIOD/global_size - beacon_delay > 640

  8. Rules • checkNT() will examine the previous round status and update the statistical value. • Once a mote receive a packet, it examine the sendID first, then examine the string of neighbor ID to judge whether it is symmetric in previous round. • If a node does not receive a packet from a certain node in a round &&nodeId is in the neighbortable-> no channel in this round.

  9. Overflow checkNTSyn[0]=1noChan[0]=2 checkNTSyn[0]=1noChan[0]=1 checkNTSyn[0]=1 Neighbor[0]=11 Cur[0]=asy Cur[0]=sym Cur[0]=noChan Cur[0]=noChan Node 10 Node 11 Cur[0]=asy Cur[0]=asy Cur[0]=sym Cur[0]=sym Neighbor[0]=10 checkNTSyn[0]=1 checkNTSyn[0]=2 checkNTSyn[0]=2 Ayn[0]=1

  10. Parameters • SEND_BEACON_PERIOD • Interval for T1 • CHECKNT_WAIT_TIMES • In which round it starts to do checkNT() • global_threshold • numSymm /(numAsymm + numSymm + numNone) >= (global_threshold/100) • Also, the system should carefully the number of round to detect symmetric

  11. Parameters checkNTSyn[0]=1noChan[0]=2 checkNTSyn[0]=1noChan[0]=1 checkNTSyn[0]=1 Neighbor[0]=11 Cur[0]=asy Cur[0]=sym Cur[0]=noChan Cur[0]=noChan Node 10 Node 11 Cur[0]=asy Cur[0]=asy Cur[0]=sym Cur[0]=sym Neighbor[0]=10 checkNTSyn[0]=1 checkNTSyn[0]=2 checkNTSyn[0]=2 Ayn[0]=1 If the motes are fully synchronized ,then the third time it could do checkNT()

  12. If motes are not fully synchronized, then forth timer is the best time to start do checkNT().

  13. Neighbor table: 7byte*MAX_NEIGHBOR • MAX_SD_BUFFER_SIZE*sizeof(TOS_Msg)) • If we do not plan to do the judgment on multiple rounds. Then we do not need to have uint8_t symmChannel[MAX_NEIGHBOR]; uint8_t asymmChannel[MAX_NEIGHBOR]; uint8_t noChannel[MAX_NEIGHBOR]; uint8_t aliveLastTime[MAX_NEIGHBOR];

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