WWW.THESES.XLIBX.INFO
FREE ELECTRONIC LIBRARY - Theses, dissertations, documentation
 
<< HOME
CONTACTS



Pages:     | 1 |   ...   | 22 | 23 || 25 | 26 |   ...   | 39 |

«Carles Gómez Josep Paradells José E. Caballero Edita: Fundación Vodafone España Autores: Carles Gómez Montenegro* Universitat Politècnica de ...»

-- [ Page 24 ] --

Congestion detection and congestion mitigation mechanisms in STCP are similar to CODA mechanisms (see section 8.2.1). However, congestion notification is carried out differently. In STCP, when the load is greater than a lower threshold (but smaller than a higher threshold), then a congestion notification bit is activated in some randomly chosen packets. If the load becomes greater than the higher threshold, then all packets are transmitted with the congestion notification bit set. When the sink node receives a packet with the congestion bit set, it activates a congestion bit in the acknowledgment. Upon receipt of such acknowledgment, the sensor node may route data through a different path or may reduce the transmission rate.

8.4.2. ESRT

The Event-to-Sink Reliable Transport (ESRT) protocol [13] was designed to achieve reliable event detection in a WSN, while aiming at conserving energy. ESRT is suitable for WSN applications that require a certain event to be detected, instead of end-to-end packet reliability. Most of the ESRT func

<

Sensors Everywhere

tionality runs on the sink node. ESRT assumes that sensor nodes periodically report the data they collect at a reporting frequency, f, and the sink node is in charge of processing the reports transmitted by the sensor nodes for detecting an event In ESRT, the sink node compares the observed event reliability, r, defined as the number of received packets during a certain interval, with the desired event reliability, R, defined as the required number of received packets during that interval for reliable event detection.

ESRT aims at achieving the desired reliability while at the same time avoiding network congestion. Sensor nodes monitor local buffer levels in order to detect congestion. If a sensor node detects congestion, it signals this fact in the next data packet it transmits to the sink node. If the sink node measures event reliability almost equal to the desired one, and no congestion notification takes place, then the WSN is operating optimally.

Otherwise, the sink node computes a new reporting frequency, f, for the next interval, which is broadcast to the source nodes. The new reporting frequency may be greater, equal to or smaller than the previous one, depending on the particular network state determined by the sink node according to its measurements.

Table 8.3 shows the different network states defined in ESRT and the corresponding actions taken by the sink node in each case.

The process is repeated until the measurements made by the sink node indicate that the WSN is operating optimally. The sink node detects congestion on the basis of local buffer occupancy measurements.

–  –  –

Table 8.3.

Summary of ESRT actions (adapted from [13]) 8.4.3. Summary Both transport protocols discussed in previous Sections 8.4.1 and 8.4.2 are generic end-to-end upstream protocols. The main differences are that while ESRT offers event reliability by means of an end-to-end source reporting frequency adjustment, STCP implements a controlled variable reliability utilizing the diversity in applications (continuous flows and event-driven flows). Table 8.4 summarises the key characteristics of these two transport protocols.

–  –  –

8.5. Transport mechanisms in ZigBee ZigBee offers support for reliable data transport between two end devices. Because ZigBee does not define a transport layer, reliability is achieved at the application layer as follows: application layer data units in ZigBee include an acknowledgment request bit. The recipient of such a data unit

–  –  –

must send an ACK back to the source. If the ACK is not received by the source, then the data unit is retransmitted. ZigBee does not provide congestion control mechanisms.

REFERENCES

[1] A. Dunkels, J. Alonso, T. Voigt, “Making TCP/IP Viable for Wireless Sensor Networks”, in proceedings of the 1st European Workshop on Wireless Sensor Networks (EWSN’04), Berlin, Germany, June 2004.

[2] A. Dunkels, “Full TCP/IP for 8-bit architectures”, in proceedings of Mobisys’03, San Francisco, USA, May 2003.

[3] L. Casals, J. Paradells, “Internet en las Cosas”; in proceedings of XV Jornadas Telecom I+D, 2005. (in Spanish) [4] Z. Shelby, “NanoIP: The Zen of Embedded Networking”, in proceedings of the IEEE International Conference on Communications, Anchorage, USA, May 2003.

[5] picnic – bringing pic and nic together (Ethernet). http://picnic.sourceforge.net.

[6] A. Dunkels, J.P. Vasseur, “IP for Smart Objects”, Internet Protocol for Smart Objects (IPSO) Alliance White Paper #1, September 2008.

[7] C. Wang et al., “A Survey of Transport Protocols for Wireless Sensor Networks”, IEEE Network, pp. 34-40, May/June 2006.

[8] Y. G. Iyer, S. Gandham, and S. Venkatesan, “STCP: A Generic Transport Layer Protocol for Wireless Sensor Networks,” Proc. IEEE ICCCN 2005, San Diego, CA, Oct. 17–19, 2005.

[9] B. Hull, K. Jamieson, and H. Balakrishnan, “Mitigating Congestion in Wireless Sensor Networks,” Proc. ACM Sensys ’04, Baltimore, MD, Nov.

3–5, 2004.

[10] C.-Y. Wan, S. B. Eisenman, and A. T. Campbell, “CODA: Congestion Detection and Avoidance in Sensor Networks,” Proc. ACM Sensys ’03, Los Angeles, CA, Nov. 5–7, 2003.





Sensors Everywhere

[11] S.-J. Park et al., “A Scalable Approach for Reliable Downstream Data Deliveryin Wireless Sensor Networks,” Proc. ACM MobiHoc ’04, Roppongi, Japan, May 24–26, 2004.

[12] C. Wang et al., “Priority-Based Congestion Control in Wireless Sensor Networks”, IEEE Int’l. Conf. Sensor Networks, Ubiquitous, and Trustworthy Comp., Taichung, Taiwan, June 5–7, 2006.

[13] Y. Sankarasubramaniam, O. B. Akan, and I. F. Akyildiz, “ESRT: Event-toSink Reliable Transport in Wireless Sensor Networks,” Proc. ACM Mobihoc ’03, Annapolis, MD, June 1–3, 2003.

[14] F. Stann and J. Heidemann, “RMST: Reliable Data Transport in Sensor Networks,” Proc. IEEE SNPA ’03, Anchorage, AK, May 11, 2003.

[15] H. Zhang et al., “Reliable Bursty Convergecast in Wireless Sensor Networks,” Proc. ACM Mobihoc ’05, Urbana-Champain, IL, May 25–28, 2005.

[16] C.-T. Ee and R. Bajcsy, “Congestion Control and Fairness for Many-toOne Routing in Sensor Networks”; Proc. ACM Sensys ’04, Baltimore, MD, Nov. 3–5, 2004.

[17] C.-Y. Wan and A. T. Campbell, “PSFQ: A Reliable Transport Protocol for Wireless Sensor Networks,” Proc. ACM WSNA ’02, Atlanta, GA, Sept. 28, 2002.

[18] C.-Y. Wan, A. T. Campbell, S. B. Eisenmann, J. Crowcroft, “Siphon:

Overload Traffic Management using MultiRadio Virtual Sinks in Sensor Networks”, in proceedings of ACM SenSys’05, San Diego, November 2005.

[19] C. Intanagonwiwat, R. Govindan, and D. Estrin. “Directed Diffusion: A Scalable and Robust Communication Paradigm for Sensor Networks”.

In Proceedings of ACM/IEEE International Conference on Mobile Computing and Networking, pp. 56-67, Boston, MA, USA, August 2000.

[20] D. Estrin, R. Govindan, J. Heidemann, and S. Kumar, “Next century challenges: scalable coordination in sensor networks”. In MobiCom ’99: Proceedings of the 5th annual ACM/IEEE international confe

<

Chapter 8. Transport

rence on Mobile computing and networking, pp. 263–270, New York, USA, 1999.

[21] C. Bormann, D. Sturek, Z. Shelby, “6LowApp: Problem Statement for 6LoWPAN and LLN Application Protocols”, Internet Draft, (Work in progress) July 2009.

[22] W. Stevens, “TCP Slow Start, Congestion Avoidance, Fast Retransmit, and Fast Recovery Algorithms”, RFC 2001, January 1997.

[23] B. Deb, S. Bhatnagar, B. Nath, “ReInForM: Reliable Information Forwarding Using Multiple Paths in Sensor Networks”, in proceedings of IEEE LCN, Bonn, Germany, October 2003.

[24] C. Gomez, M. Catalan, D. Viamonte, J. Paradells, A. Calveras, "Web browsing optimization over 2.5G and 3G: End-to-end mechanisms vs. usage of performance enhancing proxies", Wireless Communications & Mobile Computing Journal 2008.

[25] H. Balakrishnan et al. “Improving TCP/IP Performance Over Wireless Networks”, in proceedings of Mobicom’95, Berkeley, California, USA, November 1995.

[26] A. Dunkels et al. “Distributed TCP Caching for Wireless Sensor Networks”, in proceedings of the Third Annual Mediterranean Ad Hoc Networking Workshop, Turkey, June 2004.

–  –  –

9. Security The broadcast nature of wireless communications opens the door to a wide range of security attacks, and WSNs are no exception. In fact, some WSN applications may be very sensitive to security attacks. For instance, the introduction of erroneous messages in an industrial WSN, or even sometimes in a residential environment, may cause serious problems.

Security mechanisms such as encryption, authentication or communication integrity are based on cryptographic methods. These mechanisms are processing-hungry and contribute significantly to implementation code size. Hence, there is a trade-off between security functionality and hardware capabilities.

This chapter is organized as follows. Section 9.1 presents a set of security functions which may be required in WSNs. Section 9.2 focuses on how those functions are implemented in the IEEE 802.15.4 standard. Section 9.3 presents the architecture and functional description of the security services provided by ZigBee. Section 9.4 concludes the chapter with a brief overview of the current status of security mechanisms of other WSN solutions.

9.1. Security services The main security services that may be required in any network comprise

the following ones:

• Confidentiality: this service has the goal of keeping information in a secret way so that only authorized entities share this information. It is

–  –  –

typically achieved by using cryptographic mechanisms, like ciphering, which ideally should prevent an adversary to obtain even partial information.

• Authentication: the goal of this service is to make sure that a data source is the one who claims to be. In many contexts this may correspond to verifying the identity of a data source.

• Integrity: this service aims at detecting when an adversary modifies an in-transit message and hence preventing information from being changed. To achieve this goal, a Message Authentication Code (MAC) is used in each message, which constitutes a cryptographically secure checksum. Because the MAC is “signed” with a secret key that is owned only by the parties involved in the communication, the MAC provides authentication at the same time.

• Non-repudiation: this service assures that an entity involved in a communication cannot deny having taken part in that communication (as the receiver or as the sender).

9.2. Security of IEEE 802.15.4 This section is divided into two subsections. Subsection 9.2.1 presents security suites of IEEE 802.15.4-2003, while subsection 9.2.2 shows the relevant elements with regard to security introduced by IEEE 802.15.4-2006.

9.2.1. Security suites of IEEE 802.15.4 IEEE 802.15.

422 specifies eight security suites, which are summarized in Table 9.1. Such suites may be classified into four groups, depending on their characteristics: no security, cipher only, authentication only and cipher plus authentication. All security suites employ the Advanced Encryption Standard (AES) [2] as the basis for the related cryptographic operation. The In this chapter, unless explicitly mentioned, the term IEEE 802.15.4 refers to the original version of the specification (published in 2003).

–  –  –

More details on the several security suites are shown below:

• No security. This suite constitutes the identity function and does not provide security services.

• AES-CTR. This suite provides confidentiality using the AES block cipher algorithm. The sender breaks the clear-text into 16-byte blocks and computes the ci = pi ⊕ Ek (xi) operation, pi being a clear text block, ci the corresponding ciphered text and xi the value of a counter used for i-th block.

• AES-CBC-MAC. This kind of suite provides authentication and integrity by means of the CBC-MAC algorithm. The sender may compute a 4-, 8- or 16-byte MAC. This MAC may be calculated by entities sharing a symmetric key. The sender appends the MAC to the clear text. The receiver verifies this code by calculating it from the received frame and comparing it with the value included in that frame.

• AES-CCM. This kind of security suite uses CCM mode for confidentiality (cipher), authentication and integrity. Roughly, integrity protection is first applied using CBC-MAC, and after that data are ciphered together with the 4-, 8- or 16-byte MAC, using AES-CTR mode.

A relevant fact about IEEE 802.15.4 security is that it does not specify key management mechanisms. Hence, higher layer functionality must carry out key management tasks. For instance, ZigBee defines key management functionality on top of an IEEE 802.15.4 network [5].

9.2.2. Security of IEEE 802.15.4-2006

The IEEE 802.15.4-2006 [6] specification uses AES-CCM*, a minor modification of the AES-CCM mode used in the original IEEE 802.15.4 specification. AES-CCM* includes all the features of AES-CCM and includes also the cipher only and integrity only. These extra functionalities simplify the security operations. ZigBee uses IEEE 802.15.4-2006 security at MAC layer.

–  –  –

9.3. Security services of ZigBee ZigBee offers various security services that comprise key establishment, key transport, frame protection and device management [5]. Subsection 9.3.1 presents the architecture of the security services offered by ZigBee.

Subsections 9.3.2 to 9.3.4 present security mechanisms at ZigBee MAC, NWK and APL layers, respectively. Subsection 9.3.5 offers a functional description of security services in a ZigBee network.



Pages:     | 1 |   ...   | 22 | 23 || 25 | 26 |   ...   | 39 |


Similar works:

«Supreme Court of Singapore, 1 Supreme Court Lane, Singapore 178879, t: (65)-6332-1020 _ We acknowledge, with thanks, the permission of the author, editor and publisher to reproduce this article on the Singapore Judicial College microsite. Not to be circulated or reproduced without the prior permission of the author, editor and publisher. Our Vision: Excellence in judicial education and research. Our Mission: To provide and inspire continuing judicial learning and research to enhance the...»

«
 
 1 Giugno 1980 Piazza Maggiore – Bologna CLASH 
 
 
 
 abstracts
tratti
da
“Non
disperdetevi”
di
Oderso
Rubini
e
Andrea
Tinti
 
 
 
 
 Il
concerto
dei
Clash
in
Piazza
Maggiore
è
stato
l'inizio
per
tanti
musicisti
e
per
 tanti
giovani,
che
si
sono
avvicinati
per
la
prima
volta
ad
un
genere
musicale.
La
 piazza
 era
 piena
 e
 tra
 il
 pubblico
 c'erano
 tantissimi
...»

«09.10.2015 CLIPPING INTERNACIONAL NEGINT Brasília, 9 de outubro de 2015 Índice I. OMC _ 2 Africa and the WTO the Perils of Weakening the Development Agenda _ 2 EU to help Azerbaijan to complete WTO accession process _ 5 Kenya: WTO Upbeat Ahead of Key Kenya Conference _ 6 II. NEGOCIAÇÕES REGIONAIS E BILATERAIS _ 7 NAFTA is not TPP 7 Hillary Hears Perot's Giant Sucking Sound And Flips On Trade Agreement 11 Secret Trade Agreement Includes Agreement On Trade Secrets 13 Russia-Turkey Gas...»

«4 Concertinists, Concerts and Composers Introduction One early manifestation of the emerging modern music industry was a massive expansion in the number and variety of public concerts within the major urban centres of Europe during the first decades of the nineteenth century.216 Drawing upon the patronage of a rapidly expanding middleclass, they offered new opportunities for professional musicians, composers and arrangers. Satisfying the demand for concerts involved the creation of a new...»

«A Cost Effective and Reliable Zero Carbon Replacement Strategy for Diablo Canyon Power Plant V. John White and Associates 1100 11th Street, Suite 300 Sacramento, CA 95814 James H. Caldwell William Perea Marcus, JBS Energy, Inc V. John White Liz Anthony, PhD Disclaimer This work was funded by Friends of the Earth (FOE). Analysis was in part derived from the results of the Low Carbon Grid Study, which was conducted at the National Renewable Energy Lab (NREL). This report and all conclusions drawn...»

«El riesgo de deserción de prestatarios de un prestamista de microcrédito en Bolivia Mark Schreiner Marzo 2000 Microfinance Risk Management 6070 Chippewa St. #1W, St. Louis, MO 63109-3060, U.S.A. Telephone: (314) 481-9788, http://www.microfinance.com/Castellano/indice.html and Center for Social Development Washington University in St. Louis Campus Box 1196, One Brookings Drive, St. Louis, MO 63130-4899, U.S.A. Resumen Este documento describe un modelo estadístico de la calificación del...»

«Estudio de factibilidad para la producción y comercialización de kiwi con rambután en almíbar marca Zamorano en Tegucigalpa, Honduras. Alejandro Duque Venegas Zamorano, Honduras Septiembre del 2008 i ZAMORANO CARRERA DE ADMINISTRACIÓN DE AGRONEGOCIOS Estudio de factibilidad para la producción y comercialización de kiwi con rambután en almíbar marca Zamorano en Tegucigalpa, Honduras. Proyecto especial presentado como requisito parcial para optar Al título de Ingeniero en...»

«Optical Performance of the GM/CA-CAT Canted Undulator Beamlines for Protein Crystallography Robert F. Fischettia, Derek W. Yodera, Shenglan Xua, Sergey Stepanova, Oleg Makarova, Richard Benna, Stephen Corcorana, Wolfgang Dieteb, Markus Schwoerer-Boehingb, Riccardo Signoratob, Leif Schroederb, Lonny Bermanc, P. James Viccarod, Janet L. Smithae a GM/CA-CAT, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA b ACCEL Instruments GmbH, Friedrich-Ebert Straße 1, D-51429...»

«Munich Personal RePEc Archive Keynesian cross: diagrammatical interpretations of effective demand Claudia Heller and Marina Dessotti Universidade Estadual Paulista UNESP September 2007 Online at http://mpra.ub.uni-muenchen.de/5076/ MPRA Paper No. 5076, posted 30. September 2007 Cruz Keynesiana: interpretações gráficas da demanda efetiva 1 Cruz Keynesiana: interpretações gráficas da demanda efetiva ∗ Claudia Heller# Marina Vessio Dessotti× RESUMO A Teoria Geral do Emprego, dos Juros e...»

«EBD # 6.3 2012-2013 TO: ALA Executive Board RE: Report of the ALA Development Office ACTION REQUESTED/INFORMATION/REPORT: Development Office information report CONTACT: Keith Michael Fiels, Executive Director, ALA Kim Olsen-Clark, Director, ALA Development Office, kolsen-clark@ala.org DRAFT OF MOTION: DATE: April 8, 2013 ALA Executive Board Spring 2013 Report Page 1 Executive Summary The purpose of the ALA Development Office report to the ALA Executive Board Members is to provide an account of...»

«Implementation of Travel Management Services and Cliqbook Demonstration Video Transcript June 2010 Kelly May, Statewide Travel Specialist, DGS Tasha Wilson, Statewide Travel Specialist, DGS Note: Since there is continual improvement on the Cliqbook System, you may find that the location of features may slightly change. Also, see the “Cliqbook Travel How To Guide” (PDF) at http://www.caltravelstore.com. (Kelly May begins speaking) Hello! Welcome to the CALtravelstore Implementation and...»

«Copyright and use of this thesis This thesis must be used in accordance with the provisions of the Copyright Act 1968. Reproduction of material protected by copyright may be an infringement of copyright and copyright owners may be entitled to take legal action against persons who infringe their copyright. Section 51 (2) of the Copyright Act permits an authorized officer of a university library or archives to provide a copy (by communication or otherwise) of an unpublished thesis kept in the...»





 
<<  HOME   |    CONTACTS
2016 www.theses.xlibx.info - Theses, dissertations, documentation

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.