CREATING UBIQUITOUS INTELLIGENT SENSING

ENVIRONMENTS (CRUISE)

Neeli R. Prasad and Ramjee Prasad

Center for TeleInFrastructure (CTIF), Aalborg University, Denmark

Keywords: CRUISE, Environment, Intelligent Sensing, Applications, Mobility

, Security.

Abstract: The recent developments in the research and the technology have brought attention to the wireless sensor

networks as one of the key enabling technologies in the next 10 years. Ubiquitous Intelligent Sensing

Environments have promising future in supporting the everyday life of the European citizens, bringing

important social benefits for each person and for the society as a whole. Taking into account the current

fragmentation in the European research in this field, CRUISE Network of Excellence (NoE) intends to be a

focal point in the coordination of research on communication and application aspects of wireless sensor

networking in Europe. To make a significant contribution to the effectiveness of research, the consortium

will evaluate, update and communicate the State-of-the-Art in wireless sensor networking (WSN) to the

technical community, distilling a path from current technological status to a long term vision. This paper

gives an overview of different research topics in WSN and its open issues.

1 INTRODUCTION

In the past years, a number of mostly U.S.-based

research projects (Kahn et al., 1999) depicted WSNs

as large-scale networks of homogeneous, tiny,

resource-constraint sensor units. While this

characterization is valid for large class of

applications, an increasing number of sensor

network (SN) applications which are envisaged to

have immense social benefits for each European

citizen and for the society as a whole will play a

profound role in the future Ubiquitous Intelligent

Sensing Environments. WSNs in vehicles, smart

homes, smart offices, applications for road and

traffic safety, for emergency response, health

monitoring of humans, support for elder people,

monitoring of farm animals, etc are mentioned in the

literature (Prasad et al., 2004) (Arampatzis et al.,

2005) (Konrad Lorincz et al., 2004) (Anu Bhargava

et al., 2003). This big diversity of applications

requires different design considerations and

considerable multidisciplinary research efforts in the

areas of communications, electronics, control and

close collaboration between users, application

domain experts and developers.

The potential for innovative user-centric applications

as one of the m

ost exciting aspects of WSN creates a

high motivation for working on the variety of

challenging research topics (Arampatzis et al.,

2005).

In this respect, better coordination for the mostly

iso

lated and disconnected research activities on

sensor networks across Europe is essential.

CRUISE (CRUISE, see ref.) Network of Excellence

- CReatin

g Ubiquitous Intelligent Sensing

Environments, is the new project that deals with

WSNs. It actively works against this trend by

promoting discussion and strengthening research

cooperation and coordination between industry and

academia in the topic of communication and

application aspects of WSNs, while maintaining its

academic nature.

The project starts on 1

January 2006 and has

duration of 24 months. 32 internationally recognized

groups from Europe, from academia, from

independent research centers and from industry, are

coordinated by the Center for Telenfrastruktur

(CTIF) at Aalborg University, Denmark.

Convinced that Network of Excellence in this field

is a n

ecessity in this moment, the project partners

share the vision of the ubiquitous intelligent sensing

environments and work to reduce the current

weakness and fragmentation in this research field in

Europe taking into account the immense benefits

that WSNs have to offer to the European society.

355

R. Prasad N. and Prasad R. (2006).

CREATING UBIQUITOUS INTELLIGENT SENSING ENVIRONMENTS (CRUISE).

In Proceedings of the International Conference on Wireless Information Networks and Systems, pages 355-361

 SciTePress

The jointly executed program of project activities

has 3 major directions – integration of knowledge

and tools; joint research activities and spreading the

excellence.

The main focus is the creation of a state-of-the-art

Knowledge Base, available to the European society

and the general public, through information and data

collection, comparison, validation and then

dissemination. To support the research agenda of 6th

and 7th Framework Program of the European

Commission, CRUISE consortium contributes with

identification of the research gaps in the current

research work in all fields related to WSNs; with

creation of visionary scenarios for future

applications of WSNs; with identification of short

and long term benefits, done by stimulation of open

discussions on the issues of standardization and

international collaboration, by broadening the

collaboration with industries and the European

research initiatives active in this field,. CRUISE

partners are to establish frameworks of common

tools and methodologies to accelerate the research

processes and to build sustainable collaboration

links bringing strong commitments to be integrated

within and beyond the boundaries of the consortium.

An important aspect of CRUISE potential impact is

the new contribution to teaching and training in the

field of WSNs. E-learning@CRUISE is the ultimate

goal in promoting the research in Wireless Sensor

Network and in the spreading of the results to the

general public and in particular to the European

industry so that it can compete in this domain.

The project consortium is consulted by External

advisory board (EAB) on international developments

especially desires for (new) actions, projects and

activities in the area of wireless sensor networks and

applications. EAB consist of international experts in

the field of WSNs from all over the world (USA,

Turkey, Canada, Australia, Japan, The Netherlands,

UK, Switzerland, Portugal), from industry and

academia.

This paper is organized as follows: section II

provides overview of the Applications and

scenarios; section III discussed the mobility in

WSN, section IV gives the insight of security issues

in WSN and finally the paper is concluded in section

2 CRUISE APPLICATIONS AND

SCENARIOS

Within the next few years, distributed sensing and

computing will be everywhere, i.e., homes, offices,

factories, automobiles, shopping centers,

supermarkets, farms, forests, rivers, lakes, and even

pockets.

Some of the immediate commercial applications of

WSN are

• Industrial automation (process control)

• Environmental (ecology system monitoring)

• Defense (unattended sensors, real-time

monitoring)

• Utilities (automated meter reading),

• Weather prediction (temperature, humidity)

• Security (smart building, tracking, car theft

detecting)

• Building automation (HVAC controllers).

• Disaster relief operations (earthquake,

firefighting)

• Medical monitoring and instrumentation (remote

sensing and health care)

• Intelligent transportation (unmanned driving)

Research Challenges

• Numerous unattended and resource-constrained

sensors, deployed at high density in regions

requiring surveillance and monitoring. Network

topology is unknown due to unexpected node

failures.

• Sensors are memory as well as energy

constrained, and power consumption in WSN can

be divided into three domains:

• Communication, Data Processing, and Sensing

• A sensor expends maximum energy in data

communication (both for transmission and

reception), and the transceiver circuitry has both

active and start-up power consumption.

• Power consumption in data processing is much

less than in communication, so local data

processing is crucial in minimizing power

consumption in a multi-hop network.

• Tradeoff between energy and QoS

• Prolong network lifetime by sacrificing

application requirements, such as delay,

throughput, reliability, data fidelity.

3 MOBILITY

The existing state-of-the-art can be organized, on

one hand, into the analysis of different sensors,

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depending on the application and on the other hand,

the processing algorithms involved taking into

account the constrains of the devices (motes), the

monitoring process and the trade-off between delay

and throughput.

For the targeted applications, environmental

monitoring and road traffic monitoring, we have

different approaches in the state-of-the-art. For

environmental monitoring: U.S. NSF (US NSF, see

ref.) , DARPA (DARPA, see ref.) and INTEL

(INTEL, see ref.) , in U.S.; IBM Zurich (IBM , see

ref), EPFL (MICS, see ref.) in Switzerland;

Australian Research Council (Australian Research

Council, see ref.) and for road traffic monitoring:

Pravin Varaiya’s Group (Berkeley) (Pravin

Varaiya’s Group, see ref.) and Cartel People (MIT)

(Cartel People (MIT), see ref.).

Different sources of mobility are:

• Node mobility

• A node participating as source/sink (or

destination) or a relay node might move around

• Deliberately, self-propelled or by external force;

targeted or at random

• Happens in both WSN and MANET

• Sink mobility

• In WSN, a sink that is not part of the WSN

might move

• Mobile requester

• Event mobility

• In WSN, event that is to be observed moves

around (or extends, shrinks)

• Different WSN nodes become “responsible” for

surveillance of such an event

The processing algorithms to optimize sensors in

environment application and scenario within the

WSN framework can be determined by the objective

of these applications such as:

For environmental monitoring:

• Watershed and quality water monitoring, where

data is used to: a) analyze the effect of pollution in

water and soil conditions, b) track groundwater

flows

• Early detection of forest fires, where WSNs will

include temperature, light, soil moisture and air

humidity sensors to estimate evaporation, as well

as sensors to measure wind speed and direction,

allowing inferring fire risk levels and probable fire

direction.

For road traffic monitoring:

• Vehicle tracking, detection and classification (e.g.

length, speed, etc.), using acoustic, magnetic and

infrared sensors and tiny cameras

• Intelligent & efficient parking on public streets,

finding free parking spots for drivers, decreasing

the risk of possible accidents and pollution

Mobility can be described along two-axis: location

coordinate and time

• Mobile enabled WSN will provide time-varying

topological view to task managers

• Mobility maybe can be leveraged to realize the

“divide and conquer” idea, i.e. not acting until

appropriate opportunity

• Mobility management in WSN requires nano-

scale location management and topology

management

Sensor relocation can assist the deployment of

sensor network to meet certain coverage

requirement. Sensor mobility provides a time-

varying coverage that is of benefit to monitor

moving intrusion target. Mobile sink can collect

information from vicinal sensors and make decision

about its mobility pattern. The sink’s mobility

pattern can be learned and leveraged by sensors to

dynamically choose best route and finally, mobile

relay is another alternative to alleviate the burden of

energy consumption bottleneck of the sensor nodes

around the sink.

4 SECURITY

When designing a secure WSN, the following

security requirements should be considered:

authentication, integrity, freshness, availability,

confidentiality, robustness, autonomous recovery,

privacy protection, trust establishment. In the

following paragraphs, state-of-the-art for each of

them is provided and open research issues are

identified.

Authentication:

The broadcast nature of the transmission medium

makes information more vulnerable than in wired

applications. Thus, security mechanisms such as

encryption and authentication are essential to protect

information transfers.

Key management protocol:

Symmetric encryption/decryption algorithms and

hashing functions are between two to four orders of

magnitude faster than Public-key algorithms, such as

RSA, and constitute the basic tools for securing

sensor networks communications.

In (Tassos Dimitriou et al., 2005) a localized

algorithm for key establishment between a source

node and the base station suitable for sensor network

deployment is proposed. The protocol provides

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security against a large number of attacks and

guarantees that data securely reaches the base station

in an energy efficient manner.

Encryption algorithms:

TEA, SEAL, RC4, RC5 (Xiaohua Luo et al.,

2004).These encryption algorithms are suitable for

sensor networks with harsh resource constraints.

According to the comparison performed in (Xiaohua

Luo et al., 2004). TEA is the most perfect encryption

algorithm to minimize memory footprint and

maximize speed. Disadvantage of SEAL - it requires

several kilobytes of RAM space and rather intensive

computation.

RC4 is widely used in many applications and is

generally regarded to be secure.

µTesla (John Kelsey et al., 1997): Broadcast

authentication is a critical security service in sensor

networks; it allows a sender to broadcast messages

to multiple nodes in an authenticated way. µTESLA

and multi-level µTESLA have been proposed to

provide such services for sensor networks. The

propose approach removes the authentication delay

as well as the vulnerability to DOS attacks during

the distribution of µTESLA parameters, and at the

same time allows a large number of senders but

requires loosely time synchronization between

senders and receivers.

Integrity:

The danger is that information could be altered when

exchanged over insecure networks. An attacker can

perform a wide variety of attacks (once the attacker

compromised the base station or the aggregators, the

attacker could perform a denial-of-service attack and

stop responding to any queries). Since it is assumed

that a compromised node is under the full control of

the attacker, there is nothing to prevent the attacker

from mounting such denial-of-service attacks.

The approach introduced in (Bartosz Przydatek et

al., 2004) against stealthy attack is for of secure

information aggregation in sensor networks, with

analysis of the attack model and security

requirements. It proposes the aggregate-commit-

prove framework for designing secure information

aggregation protocols; proposes the approach of

forward secure authentication to ensure that even if

an attacker corrupts a sensor node at a point in time,

it will not be able to change any previous readings

the sensor has recorded locally.

Freshness:

Verifying physical presence of a neighbor in

wireless networks is one of the key components in

developing protocols resilient to replay-based

attacks. One of the key issues is how to verify

whether the given two neighbors are actually within

each other’s transmission range or not without

increasing the complexity or requiring additional

hardware; if this fundamental question can be

addressed in an efficient and scalable manner, then

the replay-based attacks can easily be determined

and eliminated by canceling fake neighboring

relations.

The Two methods proposed in (Turgay Korkmaz,

2005) are possible solutions with the objective of

increasing the rate of making correct decisions when

checking neighboring relations, supporting and

justifying the proposed ideas.

Focusing on RTS/CTS patterns in a given

neighborhood and analyze them with the objective

of detecting physically impossible neighboring

relations.

Availability:

In a sensor network many risks can result in a loss of

availability such as denial of service attacks etc. In

(Wood et al., 2002) a geographic routing protocol

for sinkhole and wormholes attack is proposed.

Sinkhole and wormholes attacks: geographic

routing protocol - Sensor networks are susceptible

to sinkhole attacks because of their specific

communication pattern, and also because all packets

share the same ultimate destination (in networks

with only one base station). Wormholes are hard to

detect because they use a private, out-of-band

channel invisible to the underlying sensor network.

Sinkholes are difficult to defend against in protocols

that use advertised information such as remaining

energy or an estimate of end-to-end reliability to

construct a routing topology because this

information is hard to verify. The situation becomes

worse when the two are used in combination.

One class of protocols resistant to these attacks is

geographic routing protocols. Geographic protocols

construct a topology on demand using only localized

interactions and information and without initiation

from the base station. Because traffic is naturally

routed towards the physical location of a base

station, it is difficult to attract it elsewhere to create

a sinkhole.

Sybil attack (Karlof et al., 2002) - In a Sybil attack,

a single node presents multiple identities to other

nodes in the network. The Sybil attack can

significantly reduce the effectiveness of fault-

tolerant schemes such as distributed storage, and

multipath. Sybil attacks also pose a significant threat

to geographic routing protocols. Location aware

routing often requires nodes to exchange coordinate

information with their neighbors to efficiently route

geographically addressed packets because by using

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the sybil attack, an adversary can “be in more than

one place at once”.

Intrusion and Misbehavior detection:

In sensor networks, many potential sources of faulty

packets exist. The source may be benign, such as a

malfunctioning sensor reporting impossible data, or

the source may be malicious - an outside attacker

performing a denial-of-service by injecting garbage

data, or a compromised node triggering false alarms

or misleading data. As possible solution, Sensor

Node Traceback Scheme (SNTS) to trace malicious

packets into the network is proposed in (Damon

Smith et al., 2004).

As the same time reliable and timely detection of

deviation from legitimate protocol operation is

recognized as a prerequisite for ensuring efficient

use of resources and minimizing performance losses.

The basic feature of attack and misbehavior

strategies is that they are entirely unpredictable. The

random nature of protocol operation together with

the inherent difficulty of monitoring in the open and

highly volatile wireless medium poses significant

challenges.

Resilience to node capture and ensuring

Confidentiality:

By using cryptography in the sensors, it is easy to

prevent attacks by unauthorized intruders. On the

other side, cryptography by itself cannot prevent

node capture or inside attackers because in this case

the attacker would have the full control over the

sensor, including the cryptographic keys.

One-time sensors - In (Kemal Bicakci et al., 2005)

the concept of one-time sensors to mitigate node-

capture attacks is proposed by utilizing the low-cost

property of sensor nodes. The idea is to preload

every sensor with a single cryptographic token

before deployment, so that any node can only insert

one legitimate message. If the sensor is captured,

this sensor can only inject a single malicious

message in the sensor network.

However this approach is not an appropriate choice

for applications that require sensors to send arbitrary

messages and the integrity and/or confidentiality of

these messages should be protected, in particular

dealing with medical care sensors.

Robustness against attacks:

WSN protocols need to be able to identify failed

neighbor nodes in real time and to adjust

accordingly to the updated topology. At the network

level, the routing protocol should be made aware of

faulty nodes to ensure that faulty nodes are routed

around.

Self diagnosing sensor nodes - A method of

introducing a level of fault tolerance into wireless

sensor networks is proposed in (Harte et al., 2005),

performed by monitoring the hardware and detecting

the status of physical malfunctions, caused by

impacts or incorrect orientation.

Software analysis is performed on the raw data from

the accelerometers to determine the orientation of

the node and to detect impacts.

Event boundary detection - The main purpose is to

identify the faulty sensors and detection of the reach

of events in sensor networks with faulty sensors.

Two novel algorithms for faulty sensor identification

and fault-tolerant event boundary detection are

proposed and analyzed in (Ding et al., 2005). These

algorithms are purely localized and thus scale well

to large sensor networks. The computational

overhead is low, since only simple numerical

operations are involved. The algorithms can be

applied as long as the “events” can be modeled by

numerical numbers.

Modeling and Detection of Misbehavior in

WSNs:

The pervasiveness of wireless sensor devices and the

architectural organization of wireless sensor

networks in distributed communities, where no trust

can be assumed, are the main reasons for the

growing interest in the issue of compliance to

protocol rules. Reliable and timely detection of

deviation from legitimate protocol operation is

recognized as a prerequisite for ensuring efficient

use of resources and minimizing performance losses.

The basic feature of attack and misbehavior

strategies is that they are entirely unpredictable. In

the presence of such uncertainty, it is meaningful to

seek models and decision rules that are robust,

namely they perform well for a wide range of

uncertainty conditions. One useful design

philosophy is to identify the rule that optimizes

worst-case performance over the class of allowed

uncertainty conditions. The situation is challenging

because several protocols operate in a non-

deterministic manner. Thus the distinction of normal

behavior from occasional misbehavior is not

straightforward.

In a wireless network, information about the

behavior of nodes is available to immediate

neighbors through direct observations. If these

measurements are compared with their counterparts

for normal protocol operation, it is then contingent

upon the detection rule to decide whether the

protocol is normally executed or not. Furthermore,

we propose to study the interaction between the

detection system and the attacker as players

participating in a zero-sum game. On the one hand,

the detection system would like to devise a detection

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rule that minimizes detection time of the attacker.

On the other hand, the attacker would like to behave

so as to prolong detection as much as possible.

Therefore, the objective function in that aspect

would be detection time.

5 CONCLUSIONS

The CRUISE project marks the start of a long-term

research and education co-operation initiative among

leading European universities and research institutes

in the field of wireless sensor networks and

applications. The results of CRUISE will be

available to interested European research

organizations, industry, SMEs and to the wide

public.

Wireless sensor networks are a reality. The market

for ZigBee devices, including smart dust, will grow

to 150 million units by 2008 creating a billion dollar

business. Much research has been done. TinyOS is a

good research platform, but not an industry strength

software.

WSNs need killer application. It is not clear what the

killer application is. But certainly environment

monitoring is not.

Nomadic user based WSN routing and Mobile

WSNs represent new challenges to do research and

development in this exciting area. Mobility in

wireless sensor networks poses unique challenges to

the medium access control (MAC) protocol design.

Previous MAC protocols for sensor networks

assume static sensor nodes and focus on energy

efficiency.

ACKNOWLEDGEMENTS

This work has been performed in the framework of

the IST-4-027738 NoE CRUISE, which is partly

funded by the European Union. The authors would

like to acknowledge the contribution of their

colleagues from the consortium.

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