Transcript Remote Deployment of Wireless Sensor Networks

Remote Deployment of
Wireless Sensor Networks
Final Presentation
April 28, 2005
Mark Robinton & Brandon Balkind
Overview
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Uplink Nodes
Protocol Review
Implementation in NS2
Future Work
Robinton&Balkind 4/28/05
Uplink Nodes
• Is it feasible to make a disposable, rapidly
deployable, remotely operating sensor uplink
node for satellite communication?
• Remember: Cost not too much of an issue—this
is military contract.
• Iridium operates at a data rate of 2400 baud,
which requires very aggressive voice
compression and decompression algorithms.
• 10 Kbps is achievable with good compression
(from Wikipedia)
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Uplink Nodes Cont’d
• By conservative estimate, this new device
should be designed to consistently operate with
15 minutes uplink tx time (for simulation
purposes)
• 900 seconds * 10 Kbps = 9000 Kbits total tx
capacity, neglecting effects of normal battery
drain (rx, think, idle, etc)
• Assume 100:1 Uplink:Sensor nodes and counter
at 3000Kbits
• 3000Kbits / 100 nodes = 30Kbits per node
3.75Kbytes per node
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Uplink Nodes Cont’d
• Remember: Sensors will only transmit
when they have meaningful information
• 100:1 is a taxing load on one uplink node
• We are using very conservative estimates
on the time a node would last
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The Protocol
• Need a method of initially electing a head
node for a randomly distributed network.
• Need to gracefully transition when the
head node’s power begins to wane.
• What to do if head node drops off the
map?
• What to do if next in line is not available?
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Network State Machine
Initial count for
home clusters
Flood collision,
Wait for end of count
Count timeout,
transfer count
Instant election,
flood results after
timeout
Low power
Running phase
(keep alives if nec.)
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Initial Packets Needed
• Discovery
– Broadcast by a head node to find out how many sensor nodes
are in its tree
• DiscoveryAck
– Reply by sensor node so uplink node can keep count
• InitElection
– Sent to any head node that needs to participate in the elction
• ElectionResult
– Packets that indicates the winner and how each sensor node
should redirect its infomation
• CountSwap
– Used to propagate any changes in the count of a node including
initial count.
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Making a packet in NS2
Header Macro
#define HDR_AODV_DIS(p) ((struct hdr_aodv_discovery*)hdr_aodv::access(p))
This casts the return of the access function as a particular type of packet
struct defintion:
Define a struct that has all the header information contained in the packet
including type, source, destination, hop count
struct hdr_aodv_discovery_ack {
u_int8_t
da_type;
// Packet Type
nsaddr_t
da_dst;
// destination
inline int size() {
int sz = 0;
/*
sz = sizeof(u_int8_t)
// da_type
+ sizeof(nsaddr_t)
// da_dst
*/
sz = sizeof(u_int8_t) + sizeof(nsaddr_t);
assert (sz >= 0);
return sz;
}
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};
Receiving a DiscoveryPkt
struct hdr_aodv *ah = HDR_AODV(p);
switch(ah->ah_type) {
case AODVTYPE_DIS:
recvDIS(p);
break;
}
Function to receive a Discovery Packet
void AODV::recvDIS(Packet *p) {
struct hdr_aodv_discovery *ds = HDR_AODV_DIS(p);
printf("Received a Discovery Packet\n");
sendDiscoveryAck(ds->dis_src);
}
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Sending a DiscoveryPkt
void AODV::sendDiscovery() {
Packet *p = Packet::alloc();
struct hdr_ip *ih = HDR_IP(p);
struct hdr_aodv_discovery *dis = HDR_AODV_DIS(p);
dis->dis_type = AODVTYPE_DIS;
dis->dis_src = index;
dis->dis_src_seqno = seqno;
dis->dis_dst = IP_BROADCAST;
dis->dis_hop_count = hop_count;
ih->saddr() = index;
ih->daddr() = IP_BROADCAST;
ih->sport() = RT_PORT;
ih->dport() = RT_PORT;
ih->ttl_ = 1;
Scheduler::instance().schedule(target_, p, 0.0);
}
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Future Work
• Finish implementation in NS2 and simulate
with different applications running.
• Add more robust features to the algorithm
to cover aforementioned corner cases
Robinton&Balkind 4/28/05
Q&A
Robinton&Balkind 4/28/05