Download [slides] Sensor network applications

Routing in Sensor Networks
Why Routing?
– Routing means carrying data packets from a source node to a
destination node (usually called sinks in sensor networks
terminology)
– Such routing paths helps to create energy-efficient data
dissemination paths between sources (sensors) and sinks (global
processing unit or human interface devices)
– Two kinds of routing: single-path and multi-path
– Since energy efficiency is the most essential factor, routing
algorithms must be robust to failures and secure against the
compromised and malicious nodes to ensure data delivery without
impacting the lifetime of the network
Algorithm for Robust Routing in Volatile
Environments (ARRIVE)
[Karlof+, 2002]
–
Probabilistic algorithm and makes packet forwarding decisions based on
localized information
–
Based on a tree-like topology rooted at the sink of the network
–
Uses forward approach to contribute to end-to-end reliability
–
Avoids packet loss by sending multiple packets of the single event
–
Three sources of packets loss expected:

Isolated link

Patterned node failures

Malicious or misbehaving nodes
ARRIVE
[Karlof+, 2002]
Terminology
–
Event: Identified by [SourceID, EventID]
–
Level: Each node has unique level indicating distance from source to sink (in terms
of hops)
–
Parents: Nodes one level closer to the sink
–
Neighbors: Nodes on the same level and be able hear each other
–
Push: Push packet to one of the neighbors
–
Forward: Forward packet to one of the parents
–
Forwarding Probability: Included in the packet header and used to probabilistically
select whether to push or forward
–
Reputation History: Each node keeps this information for each of its parents and
neighbors
–
Convergence: Prevents multiple packets of the same event being sent to same
source of failure
ARRIVE
[Karlof+, 2002]
–
Achieves diversity in paths in two ways:

Upon receiving a packet, the next hop is selected probabilistically
based on link reliability and node reputation

When more than two or more packets of the same event are
processed, these packets are ensured to follow different outgoing links
–
Takes advantage of passive participation and needs to be used cautiously
–
Each nodes keeps the following information:

Level

Neighbors list

Parents list

Reputation history of neighbors and parents

Convergence history of specific events
ARRIVE
[Karlof+, 2002]
Assumptions
–
The networks is assumed to be dense enough that sufficient multiplicity of paths
between sources and sink for algorithm to perform well
–
The network is almost considered as a static network
–
Sensors are considered to have a low per-node cost
–
Routes used by the packets are unlikely to be optimal due to the probabilistic nature
of the algorithm
–
Messages flow from nodes to sink, not the other way around
–
There is only one sink available
Performance Metrics
–
Event delivery ratio
–
Three other metrics measuring the cost of deploying ARRIVE
ARRIVE
[Karlof+, 2002]
Algorithm Description
–
Bread first search rooted at sink is used to initialize level, parents, neighbors state
information at each node
–
When a nodes hears a packets, it checks to see if the packet is addressed for it
–
If so, threshold processing takes place. Nodes are filtered by their reputation and
convergence history of the neighbors and parents
–
A decision needs to be made to either to choose to forward the packet to a parent or
push it to one of its neighbors with the probability value found in the packet header.
This is randomly determined by the forwarding probability function Pr(f).
–
Each node is weighed by their reputation. The destination is randomly selected from
the rest of the nodes (since bad reputation nodes are eliminated)
–
If the the packet is forwarded to one of the parents, Pr(f) is not changed; however, its
value is increased
Algorithm for Robust Routing in Volatile
Environments (ARRIVE) [Karlof+, 2002]
Figure 0: Overview of ARRIVE
Adapted from [Karlof+ 2002]
ARRIVE
[Karlof+, 2002]
Advantages:
–
High end-to-end reliability
–
Provides security by eliminating the compromised or malicious nodes
–
By using multiple paths to forward the same event, the probability of the
event reaching sink is increased and this also ensures to avoid packets
being forwarded to the same broken link
–
Reputation history assists in establishing a reliable path
ARRIVE
[Karlof+, 2002]
Disadvantages:
–
Extra power consumption for inactive nodes (passive listeners) are not
considered
–
Better mechanism to take care problems caused by passive listening
–
There is only one sink, packets are sent from sources to sink and not the
other way around
–
Sensor may have storage problems due to maintaining information
about its neighbors and parents (reputation history)
–
Maintaining multiple paths requires more resources
ARRIVE
[Karlof+, 2002]
Suggestions/Improvements/Future Work:
–
Beneficial to measure how much passive listening affects energy use
–
Nodes can be mobile during the simulation instead of static
–
If there is a significant mobility, state information should be updated using a
better mechanism than flooding
–
Explanation of how multiple packets are generated
–
How much redundant data is sufficient to optimize the network
–
Energy-awareness needs to be taken into consideration
–
Possibly use energy level parameter in the decision making
–
Include probabilistic analysis of the algorithm
–
Study the tradeoff the communication cost of ARRIVE vs. its robustness
–
Consider load balancing issues such that nodes near the sink deplete their
resources sooner than nodes farther away
–
Lack of quantitative analysis of passive participation for security reasons
–
Experiment with larger number of events
Rumor Routing Algorithm for Sensor Networks
[Braginsky+ 2002]
Preliminaries
Each node has its neighbor list, and an events table, with forwarding
information to all the events it knows.
After a node witnesses an event, an agent may be created, which is a
long-lived packet and travels around the network. Each agent contains
an events table, including the routing information for all events it knows.
Since an event happens in a zone, composed of several or many
nodes, it’s possible more than one agents are created from the zone
and moving in the network.
Rumor Routing Algorithm for Sensor Networks
[Braginsky+ 2002]
Algorithm Description
 When a node observes an event, it will add the event to its event table
and may also create an agent
 An agent will travel in the network and its routing table will be updated if
there is a shorter path to an event within the routing table of the node it
is visiting
In a similar way, the routing table of the currently visited node will be
updated if its route to an event is more costly than the agent’s
 Any node may generate a query for a particular event. If it knows the
route to the event, it will transmit the query. Otherwise, the query will be
sent in a random direction, and this continues until the query reach a
node which has a route to the event
Rumor Routing Algorithm for Sensor Networks
[Braginsky+ 2002]
Adapted from [Braginsky+ 2002]
Rumor Routing Algorithm for Sensor Networks
[Braginsky+ 2002]
Figure 3: The agent modifies the exist path (left)
to a more optimal one (right)
Adapted from [Braginsky+ 2002]
Rumor Routing Algorithm for Sensor Networks
[Braginsky+ 2002]
Advantages:
Deliver queries to events in large networks with less average
cumulative hops and lower energy requirements than simple flooding.
The algorithm can handle node failure gracefully, degrading its delivery
rate linearly with the number of failed nodes.
Rumor Routing Algorithm for Sensor Networks
[Braginsky+ 2002]
Disadvantages:
 The path found by the agent sometimes is not the shortest and could be
unavailable if one of the links of the path is broken.
 The agent may carry lots of routing information of events even some events
have disappeared.
 No hints from the paper about the number of agents which should be created
from the event zone.
 Can the nodes make a query for an event if no such event is existing in the
network?
 It seems that each event should have an id, but no information is provided in the
paper.
 Optimization is not considered
References
[Braginsky+ 2002] D. Braginsky and D. Estrin, Rumor Routing Algorithm for Sensor Networks, First
Workshop on Sensor Networks and Applications (WSNA), September 28, 2002, Atlanta,
Georgia, pp. 22-31.
[De+ 2003] S. De, C. Qiao, and H. Wu, Meshed multipath routing with selective forwarding: an
efficient strategy in wireless sensor networks, Computer Networks, 43, Elsevier Journal, 2003,
pp. 481-497.
[Ganesan+ 2002] D. Ganesan, R. Govindan, S. Shenker and D. Estrin, Highly Resilient, Energy
Efficient Multipath Routing in Wireless Sensor Networks, Mobile Computing and
Communications Review (MC2R) Vol 1., No. 2. 2002.
[Intanagonwiwat + 2000] C. Intanagonwiwat, R. Govindan and D. Estrin, Directed Diffusion: A
Scalable and Robust Communication Paradigm for Sensor Networks, In Proceedings of the
Sixth Annual International Conference on Mobile Computing and Networks (MobiCOM 2000),
August 2000, Boston, Massachusetts.
[Karlof+ 2002] C. Karlof, Y. Li and J. Polastre, ARRIVE: Algorithm for Robust Routing in Volatile
Environments, UC Berkley, Tech Report, May 2002.
[Pottie+ 2000] G. Pottie, W. Kaiser, L. Clare, and H. Marcy, Wireless Integrated Sensor Networks,
Communications of the ACM, Vol. 43, No. 5, pp. 51-58, May 2000
[Weilian+ 2002] W. Su and I. Akyildiz, A Stream Enabled Routing (SER) Protocol for Sensor
Networks, Med-hoc-Net 2002, Sardegna, Italy, September 2002.