Programmable Agents for Efficient Topology ... - Semantic Scholar

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REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < network. Finally, unless there exists some external means that BDs can employ in order to synchronize the time at which they begin to participate in the formation of a scatternet, the third assumption would hardly hold in a realistic PAN scenario. Indeed, it results paradoxical that BDs would be able to realize the desired synchronization, given that the purpose of creating a scatternet is to establish communications links amongst them in the first place. These and other limitations observed in existing SFPs motivated our considering the use of mobile software agents as a suitable solution to the scatternet formation problem as explained in the next section. III. APPLICABILITY OF EXISTING COMMUNICATIONS MODELS A. Communications Models in Existing SFPs Existing SFPs employ traditional communications models such as message passing and client-server to achieve their goal. In essence, message passing is employed during their initial BD discovery phase when no connections have been yet established. Some SFPs proceed to choose leader nodes that coordinate the distributed execution of the protocol, whereas others execute an algorithm that chooses a ‘super-leader’ for subsequent decision-making. In the latter approach, a centralized-processing policy is followed, wherein the ‘superleader’ takes on the role of server and the rest of the BDs behave as clients. SFPs that combine message passing and client-server models are also a common. We however argue that these communications models limit the flexibility of existing SFPs and have a clear influence over the assumptions behind them in order to keep the problem tractable. B. Mobile Processing for Wireless Network Management Mobile agents can be loosely defined as encapsulated software entities that perform a concise task on behalf of the user. Agents may act individually or may be instances of a larger process when they cooperate with other agents in order to accomplish a distributed task. There exist a large number of systems to implement mobile agents, most of which are based on the Java programming platform. In our case, we look into the Wave system as an efficient tool to implementing and deploying mobile processes given its enhanced mechanisms for distributed control and spatial coordination of software agents [15]. Wave’s architecture helps reduce much of the management overhead observed in other agent systems, while its scripting-like language offers code compactness not seen in other mobile processing platforms, making programs easy to modify [16]. This latter feature is of foremost importance in attempting to reduce the amount of bandwidth overhead that wireless ad-hoc network management protocols incur. We have previously reported efficient Wave-based solutions to wire-line network management issues [17], [18]. IV. ON-DEMAND SCATTERNET FORMATION THROUGH MOBILE PROCESSING In this section we present Bluescouts – our proposed approach for scatternet formation based on the use of mobile

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programs that overcomes weaknesses seen in cluster-head or leader election algorithms [19]. We begin by defining some assumptions for our protocol: 1) BDs are powered up sequentially according to an arbitrary (non-batched) arrival process. 2) BDs must possess a basic data forwarding mechanism to their one-hop neighbours. 3) BDs need not be within radio range of every other BD to join a scatternet. 4) Existing BDs in a piconet schedule a certain amount of time to discover new BDs. From the last assumption we note that master BDs become potentially busier than their slave counterparts as piconets and scatternets grow in size [8]. Therefore, is reasonable to expect master BDs having little or no time to spare in order to discover new BDs attempting to join an existing scatternet. As a consequence, new BDs are most likely to be discovered by existing slaves, which forces their assuming master roles. Clearly, new BDs assuming the role of master translates into the arbitrary creation of new piconets, leading to larger scatternet diameter, increased average path length, and longer data forwarding delays. Following the tacit consensus of existing SFPs, our protocol also aims at minimizing the number of piconets in a scatternet. Formally, let S/M denote the slave-to-master ratio of any given piconet P in a scatternet S. We would like to maximize the average S/M ratio across the formed scatternet in order to minimize the number of piconets C, up to a limit of G piconets. Also, let dm and ds denote master and slave devices respectively. Then,

 ∑ ds   d s ∈Pi  P∈S  ∀ dm , ds ∈ S E[ S / M ] = max   ∑ dm   Pi ∈S   

(1)

and

C = arg min [ Pi ]

(2)

P∈[1, 2,...,G ]

where

E[⋅] denotes the expectation of the S/M ratio of the

piconets in the scatternet. A. Reconfiguration Attempt at the Local Piconet We describe the details of our protocol by contemplating a sample situation in which users with portable electronic devices arrive at a certain venue according to our previous assumptions. Here, role reconfiguration attempts would only take place if an existing slave BD discovers a newly joined BD, wherein a wave agent would be dispatched in an initial intra-piconet reconfiguration attempt as exemplified in Figure 2. An agent carrying the current values of the hardware clock (CLK) and Bluetooth device address (BD_ADDR) is forwarded by the slave node that discovered the new BD, herein referred to as anchor node, to its own piconet master.

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Scatternet size (nodes) Fig. 9. Slave/Master ratio

Bandwidth overhead has not been accounted for in any of the existing approaches. Results on the number of packets sent by the proposed protocol were reported in [7], although the actual packet size is unknown. In any case the amount of bandwidth incurred by our approach can be considered reasonable small, which is an advantage of employing mobile agent technology efficiently.

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VI. CONCLUSIONS We have presented a novel scatternet formation protocol based on mobile agent technology that allows overcoming several issues seen in existing schemes. Bluescouts benefits from the characteristics of agent-based systems in various ways. First, the mobile agent approach enables the protocol to

> REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < execute in a completely distributed and asynchronous fashion as BDs need not execute the protocol concurrently when new devices attempt to join an existing piconet/scatternet. This clearly helps in reducing the processing load on individual devices as compared to centralized approaches, enables a dynamic and gradual organic-like growth of a scatternet as users arrive, and scales well to networks of moderately large size. Second, while existing SFPs require each BD to possess an exact copy of the protocol in order to ensure a flawless execution, our programmable approach enables a flexible context-aware scatternet formation in which BDs may interconnect according to fully customizable policies. For the sake of simplicity, the protocol used during our simulations followed a predefined policy that enabled new BDs to join an existing scatternet as quickly as possible. However, other policies may be introduced in which the BD reconfiguration would occur depending on other factors, such as the type of device connecting to, link capacity, or even available services according on the needs of the user. Third, our protocol is much more flexible since it decouples the actual scatternet formation procedure from device discovery. Bluescouts relies on existing APIs that employ either mandatory schemes or even much more efficient variations thereof in order to discover new devices, if available [22]. Thus, in contrast to many other approaches, no manipulating, changing or enhancing of the existing device discovery scheme is necessary. Additional improvements to our protocol include mechanisms to ensure deadlock avoidance, which is always a potential issue due to the instability of the wireless channel. In addition, the protocol can be extended to allow the concurrent reconfiguration of more than a single device at a time when dealing with batched BD arrivals. Security concerns normally attributed to agent systems at the application level are not considered a major threat here given the closed nature of our system, and are considered out of the scope of this paper. REFERENCES [1]

El-Sayed, M and Jafee, J. “A View of Telecommunications Network Evolution.” IEEE Communications Magazine, December 2002. [2] IEEE 802.15 Working Group for WPAN standards. http://grouper.ieee.org/groups/802/15. [3] Johansson, P. et al. “Bluetooth – An Enabler of Personal Area Networking.” IEEE Network, Special Issue in Personal Area Networks, September 2001. [4] Bisdikian, C. “An Overview of the Bluetooth Wireless Technology.” IEEE Communications Magazine, December 2001. [5] Schneiderman, R. “Bluetooth’s Slow Dawn”, IEEE Spectrum Online, January 2001. [6] Bluetooth Special Interest Group Specification, Version 1.2, http://www.bluetooth.com. [7] Law, C. Mehta, A. K. and Siu, K.-Y. “Performance of a New Bluetooth Scatternet Formation Protocol”. In ACM Symposium on Mobile Ad Hoc Networking and Computing, Long Beach, CA, October 2001. [8] Tan, G. et. al., “An Efficient Scatternet Formation Algorithm for Dynamic Environments”, In IASTED Communications and Computer Networks (CCN), Cambridge, MA, November 2002. [9] Zaruba, G.V., Basagni S. and Chlamtac, I., "Bluetrees - Scatternet Formation to Enable Blue- tooth-Based Ad Hoc Networks", In Proc. IEEE ICC'01, June 2001. 27 [10] Ramachandran, L. et al "Clustering Algorithms for Wireless Ad Hoc Networks," In Proceedings of the 4th International Workshop on

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Discrete Algorithms and Methods for Mobile Computing and Communications, Boston, MA, USA, 2000. Salonidis, T. et. al., “Distributed Topology Construction of Bluetooth Personal Area Networks.” In Proc. IEEE INFOCOM, Anchorage, AK, April 2001. Basagni, S. and Petrioli, C. “A Scatternet Formation Protocol For Ad Hoc Networks of Bluetooth Devices.” In Proceedings of the IEEE Semiannual Vehicular Technology Conference, VTC May 2002, Birmingham, AL, USA. Basagni, S., Petrioli, C. "Degree-Constrained Multihop Scatternet Formation for Bluetooth Networks." In Proceedings of the IEEE Globecom, Taipei, Taiwan, November 2002. Wang, Z., Thomas, R. and Haas, Z. “Bluenet – A New Scatternet Formation Scheme.” Appeared at the 35th Annual Hawaii International Conference on System Sciences (HICSS'02), Hawaii, January, 2002. Sapaty, P. “Mobile Processing in Distributed and Open Environments”. John Willey & Sons, 2000. Vuong, S. T. and Ivanov, I. “Mobile Intelligent Agent Systems: Wave Vs. Java”. IEEE Computer Society, March 1996. González-Valenzuela, S. and Leung, V.C.M., “QoS-Routing For MPLS Networks Employing Mobile Agents”. IEEE-Network, May-June 2002. Vuong, S and Mathy, M. “Simulating The Mobile-IP Protocol Using Wave.” In Proceedings of The First International Conference on Emerging Technologies and Applications in Communications, IEEE Computer Society, Portland, May 1996. González-Valenzuela S., Vuong S.T., and Leung V.C.M., "BlueScouts A Scatternet Formation Protocol Based on Mobile Agents " In proceedings of the IEEE 4th Workshop on Aplications and Services in Wireless Networks, Boston, USA, August 2004. Borst, P. “An Architecture for Distributed Interpretation of Mobile Programs”. PhD dissertation, Faculty of Informatics, University of Karlsruhe, 2001. The Wave Page, Faculty of Informatics, University of Karlsruhe, http://www-zorn.ira.uka.de/Wave/Wave.html. Cheolgi, K. Joongsoo, M. and Joonwon, L. "A Random Inquiry Procedure Using Bluetooth" IEICE Transactions on Communications, Vol. E86-B, No. 9, September 2003.

Sergio González-Valenzuela received the B. Eng. degree (with special mention) in Electronics Engineering from Instituto Tecnológico de Sonora (ITSON), Ciudad Obregón, Mexico, in 1995, and the M.A.Sc. degree in Data Communications from the University of British Columbia (UBC), Vancouver, Canada, in 2002. From 1995 to 1999, he held various engineering positions in the Mexican industry. He is currently working toward the Ph.D. degree in the Department of Electrical and Computer Engineering, UBC, where he is a member of the Data Communications Group.

Son T. Vuong received his Ph.D. in computer science from the University of Waterloo, Waterloo, Canada. In 1981 and 1982 he was on the faculty of the Department of Computer Science at the University of Waterloo. Since 1983 he has been on the faculty of the Department of Computer Science of the University of British Columbia and is now Director of the Laboratory for Networks and Internet Computing (NICLab). He is an international renowned researcher on protocol engineering, advanced networks, and mobile and collaborative computing. He has (co) authored a US patent, over 140 papers and co-edited three books, including the book on “Recent Advances in Distributed Multimedia Systems” published in 1999. He served on several conference program committees and was (Co)chair and organizer of five international conferences (IWVS’04, DMS'97, ICDCS'95, PSTV'94, FORTE'89, IWPTS'88).

> REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < Victor C. M. Leung received the B.A.Sc. (Honors) degree in electrical engineering from the University of British Columbia (UBC), Vancouver, BC, Canada, in 1977 and the Ph.D. degree in electrical engineering from UBC in 1981 on a Natural Sciences and Engineering Research Council Postgraduate Scholarship. From 1981 to 1987, he was Senior Member of Technical Staff at Microtel Pacific Research Ltd. (later renamed MPR Teltech Ltd.), Burnaby, BC, specializing in the planning, design, and analysis of satellite communication systems. He also held a parttime position as Visiting Assistant Professor at Simon Fraser University, Burnaby, BC, in 1986 and 1987. In 1988, he was a Lecturer in the Department of Electronics, Chinese University of Hong Kong. He joined the Department of Electrical Engineering at UBC in 1989, where he is a Professor, holder of the TELUS Mobility Industrial Research Chair in Advanced Telecommunications Engineering, and a Member of the Institute for Computing, Information and Cognitive Systems. He was a Project Leader and a Member of the Board of Directors in the Canadian Institute for Telecommunications Research, a Network of Centres of Excellence funded by the Canadian Government. His research interests are in the areas of architectural and protocol design and performance analysis for computer and telecommunication networks, with applications in satellite, mobile, personal communications, and high-speed networks. Dr. Leung was awarded the APEBC Gold Medal as the head of the graduating class in the Faculty of Applied Science in 1977. He is an Editor of the IEEE TRANSACTIONS ONWIRELESS COMMUNICATIONS and an Associate Editor of the IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY. He is a Voting Member of the Association for Computing Machinery (ACM).

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