AD HOC Reviewers

We present a new metric, Expected Data Rate (EDR), for accurately finding high-throughput paths in multi- hop ad hoc wireless networks. Our metric is based upon a new model for transmission interference which is a critical factor in determining path throughput. We construct a realistic and practical transmission interference model by (1) determining transmission contention degree of each link as a function of the wireless link loss, (2) quantifying the impact of the wireless link loss on medium access backoff, and (3) considering possible concurrent transmissions when two links do not interfere with each other. Our transmission interference model also takes the non-optimality of IEEE 802.11 medium access scheduling into account. Using extensive ns-2 simulations of IEEE 802.11 ad hoc networks, we find that EDR can accurately determine the achievable data rates of ad hoc paths, thereby significantly outperforming the other existing metrics. I. INTRODUCTION Multi-hop ad hoc wireless networks provide a flexible solution to applications where wireless users, mobile or not, wish to communicate with each other without a fixed wired infrastructure. Efficient ad hoc routing protocols are necessary to extract optimal performance from these networks. There has been a lot of research on designing and developing efficient ad hoc routing protocols. Some of these efforts have extended existing wired network routing protocols to the wireless sce- nario. More recently, research on ad hoc routing has been focusing on understanding the characteristics of the shared wireless medium, and on incorporating these characteristics in determining ad hoc path performance metrics for finding best ad hoc paths. Although interesting, the existing research on finding suitable path metrics only provides a good beginning. It fails to fully address some of the fundamental properties of multi-hop ad hoc wireless networks and hence the existing path metrics are not very accurate. A simple metric for finding ad hoc paths in multi-hop wireless networks is minimum hop count. There are many existing routing protocols based on this metric including Dynamic Source Routing (DSR) (1), and Ad Hoc On-Demand Distance Vector Routing (AODV) (2). These approaches use shortest-path routing, implicitly assuming that links either work perfectly or do not work at all. They do not consider the wireless link loss. The shortcomings of shortest-path routing using only the minimum hop count metric have been investi- gated recently (3)-(5). The results of (3)-(5) consistently show that the wireless link loss must also be considered in the path metric for finding high performance ad hoc paths. In this paper, we develop a new path metric that we call Expected Data Rate or EDR in short. Our metric accurately determines the data rates of ad hoc paths in multi-hop ad hoc wireless networks. In order to develop EDR, we use an accurate understanding for transmission interference in the shared wireless medium. Transmission interference is a fun- damental property of shared wireless networks. It is a critical factor in determining ad hoc path throughput. We find that transmission interference behavior is highly dependent upon the wireless link loss rates. Existing path metrics, including even those that consider wireless link loss, do not address this dependence. Interestingly, we find that the transmission interference does not only depend upon the wireless link loss rates, but also on the ordering of link loss rates along the ad hoc path. We construct a realistic and practical transmission interference model in the context of the IEEE 802.11 medium access control protocol (6) by (1) determining transmission contention degree of each link as a function of the wireless link loss, (2) quantifying the impact of the wireless link loss on medium access backoff, and (3) considering possible concurrent transmissions when two links do not interfere with each other. Our transmission interference model also takes the non-optimality of IEEE 802.11 medium access scheduling into account. Using extensive ns-2 simulations, we find that our new path metric EDR, can fairly accurately determine the achievable data rates of ad hoc paths. Unlike existing path metrics, EDR can find best ad hoc paths in almost all cases that we study. The remainder of this paper is organized as follows. In the next section, we present the existing work. In Section III, we motivate our ideas to demonstrate the limitation of the existing metric. Section IV describes our problem setting. In Section V, we develop the transmission interference model in the presence of lossy links. Our new metric EDR is also presented in the section. Issues about incorporating EDR into existing ad hoc routing algorithms are discussed in Section VI. In Section VII we evaluate the performance of EDR and demonstrate its superior performance over the existing path metrics. We conclude our work in Section VIII.

Preface AD HOC WIRELESS NETWORKS A Modular Cross Layer Architecture for Ad Hoc Networks, M. Conti, J. Crowcroft, G. Maselli, and G. Turi Routing Scalability in MANETs, J. Eriksson, S. Krishnamurthy and M. Faloutsos Uniformly Distributed Algorithm for Virtual Backbone Routing in Ad Hoc Wireless Networks, D.S. Kim Maximum Necessary Hop Count for Packet Routing in MANET, X. Chen and J. Shen Efficient Strategyproof Multicast in Selfish Wireless Networks, X.-Yang Li Geocasting in Ad Hoc and Sensor Networks, I. Stojmenovic Topology Control for Ad hoc Networks: Present Solutions and Open Issues, C.-C. Shen and Z. Huang Minimum-Energy Topology Control Algorithms in Ad Hoc Networks, J.Y. Halpern and L. Li Mathematical Models and Exact Algorithms for the Min-Power Symmetric Connectivity Problem: An Overview, R. Montemanni, L.M. Gambardella and A.K. Das A Survey on Algorithms for Power Assignment in Wireless Ad Hoc Networks, G. Calinescu, O. Frieder, and P.-J. Wan Energy Conservation for Broadcast and Multicast Routings in Wireless Ad Hoc Networks, J.-P. Sheu, Y.-S. Chen, and C.-Y. Chang Linear Programming Approaches to Optimization Problems of Energy Efficiency in Wireless Ad Hoc Networks, H. Liu and X. Jia Wireless Networks World and Security Algorithms, N. Sklavos, N.A. Moldovyan, and O. Koufopavlou Reliable Computing in Ad Hoc Networks, P.Th. Eugster Medium Access Control Protocols in Mobile Ad Hoc Networks: Problems and Solutions, H. Zhai and Y. Fang On Using Ad Hoc Relaying in Next Generation Wireless Networks, B.S. Manoj and C.S. Ram Murthy Ad Hoc Networks: A Flexible and Robust Data Communication, M. Abolhasan and T. Wysocki Adaptive Cycle-Controlled E-Limited Polling in Bluetooth Piconets, J. Misic and V.B. Misic Scalable Wireless Ad hoc Network Simulation, R. Barr, Z.J. Haas, and R. van Renesse SENSOR NETWORKS Sensor Systems: State of the Art and Future Challenges, D.P. Agrawal, R. Biswas, N. Jain, A. Mukherjee, S. Sekhar, and A. Gupta How To Structure Chaos: Initializing Ad Hoc and Sensor Networks, T. Moscibroda and R. Wattenhofer Self Organization of Wireless Sensor Networks, M. Kochhal, L. Schwiebert, and S. Gupta Self-Stabilizing Distributed Systems and Sensor Networks, Z. Shi and P.K. Srimani Time Synchronization in Wireless Sensor Networks, Q. Ye and L. Cheng Routing and Broadcasting in Hybrid Ad Hoc and Sensor Networks, F. Ingelrest, D. Simplot-Ryl, and I. Stojmenovi Distributed Algorithms for Deploying Mobile Sensors, G. Cao, G. Wang, T. La Porta, S. Phoha, and W. Zhang Models and Algorithms for Coverage Problems in Wireless Sensor Networks, C.-F. Huang, P.-Y. Chen, Y.-C. Tseng, and W.-T. Chen Maintaining Sensing Coverage and Connectivity in Large Sensor Networks, H. Zhang and J.C. Hou Advances in Target Tracking and Active Surveillance using Wireless Sensor Networks, Y. Zou and K. Chakrabarty Energy Efficient Detection Algorithms for Wireless Sensor Networks, C. Tang and C.S. Raghavendra Comparison of Cell-Based and Topology-Control-Based Energy Conservation in Wireless Sensor Networks, D.M. Blough, M. Leoncini, G. Resta, and P. Santi QoS Support for Delay Sensitive Applications in Wireless Networks of UAVs, I. Cardei A Scalable Solution for Securing Wireless Sensor Networks, A. Wadaa, K. Jones, S. Olariu, L. Wilson and M. Eltoweissy Antireplay Protocols for Sensor Networks, M.G. Gouda, Y.-r. Choi and A. Arora Low Power Consumption Features of the IEEE 802.15.4 WPAN Standard, E.H. Callaway, Jr. PEER-TO-PEER NETWORKS Peer-to-Peer: A Technique Perspective, W. Zheng, X. Liu, S. Shi, J. Hu, H. Dong Searching Techniques in Peer-to-Peer Networks, X. Li and J. Wu Semantic Search in Peer-to-Peer Systems, Y. Zhu and Y. Hu An Overview of Structured P2P Overlay Networks, S. El-Ansary and S. Haridi Distributed Data Structures for Peer-to-Peer Systems, J. Aspnes and G. Shah State Management in DHT with Last-Mile Wireless Extension, H.-C. Hsiao and C.-T. King Topology Construction and Resource Discovery in Peer-to-Peer Networks, D. Li, X. Lu, and C. Xu Peer-to-Peer Overlay Optimization, Y. Liu, L. Xiao, and L.M. Ni Resilience of Structured Peer to Peer Systems: Analysis and Enhancement, D. Xuan, S. Chellappan, and X. Wang SWAN: Highly Reliable and Efficient Network of True Peers, F.B. Holt, V. Bourassa, A.M. Bosnjakovic, and J. Popovic Scalable and Secure P2P Overlay Networks, H. Shen, A.S. Brodie, C.-Z. Xu, and W. Shi Peer-to-Peer Overlay Abstractions in MANETs, Y.C. Hu, S.M. Das, and H. Pucha

The next generation mobile communication systems will be based on infrastructure wired/ wireless LAN technologies and ad hoc networks. Such hybrid networks benefit the extension of infrastructure network coverage using ad hoc connectivity apart from offering the ad hoc nodes access to the resources of the wired/infrastructure networks. In most of the integration strategies Mobile IP is integrated with the ad hoc network routing protocol to provide Internet access and in few of the strategies the routing protocol has been enhanced to provide the connectivity without using Mobile IP.Few strategies use fixed gateways, others use mobile gateways. In this paper, we proposed two different approaches of integrating ad hoc network and the wired network using two different protocols. In the first part of this paper, an extended DSDV protocol, named as Efficient DSDV (Eff-DSDV) protocol is used to provide bi-directional connectivity between exclusive ad hoc hosts and the hosts on the Internet (wired network). The proposed framework uses one of the ad hoc hosts known as Mobile Gateway Node (MGN) to act as a bridge between ad hoc network and the Internet. The performance comparison is made between the proposed approach and one of the leading strategies based on packet delivery ratio, end-end delay, and control overhead. The experimental results indicate that the performance of the proposed strategy is better than the existing strategies.Later in the paper, we propose a framework for integrating mobile ad hoc network and the Internet using both fixed and mobile gateways. The ad hoc hosts can access the Internet using either fixed or mobile gateway, based on criteria of distance, load on the gateway. An extended version of AODV routing protocol is used in the framework. The objective behind using both fixed and mobile gateways is to increase the reliability of the Internet access, scalability, providing transparent Internet access to the ad hoc hosts and in general improve the performance of the integrated framework. The proposed framework is a hybrid architecture involving two-layer and three-layer approaches of integration. The performance comparison of the two proposed strategies has been done under common metrics. KeywordsMobile Ad Hoc Network (MANET)Integration StrategyMobile Gateway Node (MGN)Routing ProtocolEff-DSDVFixed GatewaysMobile Gateways

Ad hoc social networks are special social networks, such as ad hoc tactical social networks, ad hoc firefighter social networks, and ad hoc vehicular social networks. The social networks possess both the properties of ad hoc network and social network. One of the challenge problems in ad hoc social networks is opinion impact and consensus, and the opinion impact plays a key role for information fusion and decision support in ad hoc social networks. In this paper, consider the impact of physical and logical distance on the opinions of individuals or nodes in heterogeneous social networks; we present a general opinion impact model, discuss the local and global opinion impact models in detail, and point out the relationship between the local opinion impact model and the global opinion impact model. For understanding the opinion impact models easily, we use the general opinion impact model to ad hoc tactical social networks and discuss the opinion impact and opinion consensus for ad hoc tactical social networks in the end.

To the classicist, phrases like the legal corpus delicti and amicus curiae, like the aesthetic deus ex machina and ad unguem carry a certain unction as pre servative of a language the classicist loves. But who can say the same ad hoc, that ubiquitous prefix to Com mittee ? Seemingly, no group assigned a task in univer sity or college or high school or in any educationally ad ministrative or advisory body whatsoever can be other than an Ad Hoc Committee.,, What, really, does ad hoc add to a committee's func tion? The phrase, presumably, means for or for this purpose or for the business at hand. But is not every appointed for or for this pur pose or for the business at hand ? By what linguistic legerdemain can an ad hoc be expected to achieve what a simple committee without a qualify ing Latin prefix could not likewise bring about ? One might wish, of course, that there were no more to ad hoc than this. However, one feels, it is to be feared, in an ad hoc committee, that sense of immediacy which is so blithesomely rampant in Academia today. To do it now, immediately, without delay (and perhaps without much thought) seems to have pervaded the breath of our academic lives, often to the exclusion of any sane and reasoned approach to problems and ques tions which may well be frighteningly in need of an swers.

Abstract. Documentation of archaeological and cultural heritage sites is at the heart of the archaeological process and an important component in cultural heritage research, presentation and restorations. In 2012 the Superintendence of Cultural Heritage of Aosta Valley – IT (Soprintendenza per i Beni e le Attività Culturali della Region e Autonoma Valle d'Aosta) carried out a complex archaeological excavation in a composite archaeological context, situated an urban background: the Aosta city centre. This archaeological excavation has been characterized by the classical urban archaeological issues: little space, short time, complex stratigraphy. Moreover the investigations have come out several structures and walls that required safety and conservation measures. Ad hoc 3D solutions carried out a complete 3D survey of the area in 10 different time/situations of the Archaeological digs, chosen in collaborations with the archaeological staff. In this way a multi temporal 3D description of the site has been provided for the archaeological analysis and for the project of the restorations activities. The 3D surveys has been carried out integrating GPS, laser scanner technology and photogrammetry. In order to meet the needs of the site, and its complex logistics and to obtain products that guarantee the high quality and detail required for archaeological analysis, we have developed different procedures and methodologies: hdr imaging for 3D model with correct, consistent and uniform colours, noise filtering and people filtering, for the removal of interference between laser instrument and object of the survey, Advanced laser scanner triangulation, in order to consider both artificial and natural tie points, for a correct registration of a huge amount of scans. Single image orientation on 3D data, in order to integrate the laser data with data coming from digital photogrammetry (faster on the field than the laser scanner survey, than used in certain situations). The results of all these methodologies and procedures will be presented and described in the article. For the documentation of the archaeological excavations and for the management of the conservation activities (condition assessment, planning, and conservation work). Ad Hoc 3D solutions has costumized 2 special plug-ins of its own software platform Ad Hoc: Ad Hoc Archaeology and Ad Hoc Conservation. The software platform integrates a 3D database management system. All information (measurements, plotting, areas of interests…) are organized according to their correct 3D position. They can be queried using attributes, geometric characteristics or their spatial position. The Ad Hoc Archaeology plug-in allows archeologists to fill out UUSS sheets in an internal database, put them in the correct location within the 3D model of the site, define the mutual relations between the UUSS, divide the different archaeological phases. A simple interface will facilitate the construction of the stratigraphic chart (matrix), in a 3D environment as well (matrix 3D). The Ad Hoc Conservation plug-in permits conservators and restorers to create relationships between the different approaches and descriptions of the same parts of the monument, i.e.: between stratigraphyc units or historical phases and architectural components and/or decay pathologies. The 3D DBMS conservation module uses a codified terminology based on "ICOMOS illustrated glossary of stone deterioration" and other glossary. Specific tools permits restorers to compute correctly surfaces and volumes. In this way decay extension and intensity can be measured with high precision and with an high level of detail, for a correct time and costs estimation of each conservation step.

The year 2005 witnesses the third occasion that the Wireless Personal Area and Ad-hoc Networks minitrack is part of the annual HICSS conference. This year there was a substantial increase in submissions (thus a substantial decrease in the acceptance rate), indicating the growing importance of research in this area. The minitrack is also focused on fundamental challenges and issues arising in wireless sensor networks and their applications. Wireless sensor networks differ from other wireless networks in the need for unattended and very low-energy operation, in the possibility of collaboration and distributed sensor calibration, and in the mission oriented nature of most sensor networks. Thus our mini track looks at two very important streams of research. After a strict review process nine papers were selected to be included in the program of the minitrack. The first paper is titled “BT-Crowds: Crowds-style Anonymity with Bluetooth and Java,” presenting an interesting idea on how anonymity can be achieved when sending messages in WPAN environments. Our second paper revisits scatternet formation issues of Bluetooth based ad hoc networks thus the title: “A Dynamic and Distributed Scatternet Formation Protocol for Real-life Bluetooth Scatternets.” The third paper is titled “Secure Dynamic Source Routing” and presents a new variant of the DSR routing protocol with special emphasis on security. In the fourth paper, the discussion concerns “Routing Based Feedback towards Applications in Mobile Ad Hoc Networks,” where routing notifications are relayed via event channels. “A Location Service Mechanism for Position-Based Multicasting in Wireless Mobile Ad hoc Networks” is the title of the fifth paper in the minitrack. It presents some innovative ideas on how location information can be managed for multicast communications in ad-hoc networks. In the sixth paper, “Sliding Window Protocol for Secure Group Communication in Ad Hoc Networks,” the authors propose a sliding window protocol for determining multiple routes in a multi-communications environment. In the seventh paper titled “Ad Hoc Routing Protocol Avoiding Route Breaks Based on AODV,” the authors propose improvements to the well-known AODV ad hoc routing protocol The eight paper, “Joint Scheduling and Routing Algorithm for Ad Hoc Wireless,” presents an innovative and interesting idea wrapped around an iterative algorithm on power control. In the final paper of the minitrack, “Performance Issues of Ad Hoc Routing Protocols in a Network Scenario used for VideoPhone Applications,” the authors present a simulation based performance analysis of different ad hoc routing protocols using the application pointed to in the title. These papers highlight some of the issues and work towards solutions in Personal Area and ad hoc networks which are among the most active research fields in wireless networking. We believe that the papers will provide opportunities for researchers to come together and discuss and debate the results of the interesting experiments that are described in the papers. We are confident that the minitrack will achieve its goal of bringing together leading researchers, to present new results and discuss synergies between the two areas. We also take this opportunity to thank all the reviewers for their valuable and professional work as well as all the authors who submitted papers and thus helped us to create such a strong minitrack. We would also like to express our sincere gratitude to the conference organizers for their hard work and help.

Network security and energy consumption are deemed to be two important components of wireless and mobile <i>ad hoc</i> networks (WMANets). There are various routing attacks which harm <i>Ad Hoc</i> networks. This is because of the unsecure wireless communication, resource constrained capabilities and dynamic topology. In order to cope with these issues, <i>Ad Hoc</i> On-Demand Distance Vector (AODV) routing protocol can be used to remain the normal networks functionality and to adjust data transmission by defending the networks against black hole attacks. The proposed system, in this work, identifies the optimal route from sender to collector, prioritizing the number of jumps, the battery life, and security, which are fundamental prerequisites. Researches have proposed various plans for detecting the shortest route, as well as ensuring energy conversions and defense against threats and attacks. In this regard, the packet drop attack is one of the most destructive attack against WMANet communication and hence merits special attention. This type of attack may allow the attacker to take control of the attacked hubs, which may lost packets or transmitted information via a wrong route during the packets journey from a source hub to a target one. Hence, a new routing protocol method has been proposed in this study. It applies the concept of energy saving systems to conserve energy that is not required by the system. The proposed method for energy aware detection and prevention of packet drop attacks in mobile <i>ad hoc</i> networks is termed the <i>Ad Hoc</i> On-Demand and Distance Vector–Packet Drop Battling Mechanism (AODV–PDBM).

This study compares effects of status on group decision making in ad hoc student and real supervisor-subordinates groups. Eighteen ad hoc and eighteen real groups of three with one high status and two low status members made decisions on two standard choice-dilemma problems. For each group member, compliance, persuasion, recidivism of opinion, perceived competence-influence, and attractiveness were measured. The results of the T-test and correlational analysis, conducted upon the differences between respective values for a high and average low status individuals, revealed that in both, ad hoc and real groups, high status members had stronger actual and perceived influence on group decisions and attitudes of other group members than low status individuals. In ad hoc and real groups, high status members were the first advocates more frequently than low status members. Analysis of variance showed that the influence of high status members was the strongest, if they were also the first advocates. At the same time, the public compliance of low status members under power pressure, and therefore, consequent recidivism of opinion was significant only in the real groups and not in the ad hoc groups. High status members were first advocates much more frequently in the real groups than in the ad hoc groups. Perceived influence of group members strongly correlated with likability only in the real groups. The correlation was close to zero in the ad hoc groups. Based on our previous study on “status equalization phenomenon” in ad hoc groups communicating electronically, we suggest that in real groups as well, the influence of status can be controlled, at least partially, by technically monitoring access of group members to the first advocacy.

Popper's explications of 'ad hoc' in relation to hypotheses and explanations turn out to be either trivial, confused or mistaken. One such explication I discuss at length is circularity; another is reduction in empirical content. I argue that non-circularity is preferable to non-ad hocness for an acceptable explanation or explanans, and I isolate some persistent errors in his analysis. Second, Popper is barking up the wrong tree in proscribing reductions in empirical content in novel hypotheses. Such reductions may constitute scientific progress. He fails to show that ad hoc hypothesis are the threat to science he claims.

Ad Hoc Routing with Distributed Ordered Sequences

The importance of Clinical Data Warehouses (CDW) has increased significantly in recent years as they support or enable many applications such as clinical trials, data mining, and decision making. CDWs integrate Electronic Health Records which still contain a large amount of text data, such as discharge letters or reports on diagnostic findings in addition to structured and coded data like ICD-codes of diagnoses. Existing CDWs hardly support features to gain information covered in texts. Information extraction methods offer a solution for this problem but they have a high and long development effort, which can only be carried out by computer scientists. Moreover, such systems only exist for a few medical domains. This paper presents a method empowering clinicians to extract information from texts on their own. Medical concepts can be extracted ad hoc from e.g. discharge letters, thus physicians can work promptly and autonomously. The proposed system achieves these improvements by efficient data storage, preprocessing, and with powerful query features. Negations in texts are recognized and automatically excluded, as well as the context of information is determined and undesired facts are filtered, such as historical events or references to other persons (family history). Context-sensitive queries ensure the semantic integrity of the concepts to be extracted. A new feature not available in other CDWs is to query numerical concepts in texts and even filter them (e.g. BMI > 25). The retrieved values can be extracted and exported for further analysis. This technique is implemented within the efficient architecture of the PaDaWaN CDW and evaluated with comprehensive and complex tests. The results outperform similar approaches reported in the literature. Ad hoc IE determines the results in a few (milli-) seconds and a user friendly GUI enables interactive working, allowing flexible adaptation of the extraction. In addition, the applicability of this system is demonstrated in three real-world applications at the Wurzburg University Hospital (UKW). Several drug trend studies are replicated: Findings of five studies on high blood pressure, atrial fibrillation and chronic renal failure can be partially or completely confirmed in the UKW. Another case study evaluates the prevalence of heart failure in inpatient hospitals using an algorithm that extracts information with ad hoc IE from discharge letters and echocardiogram report (e.g. LVEF < 45 ) and other sources of the hospital information system. This study reveals that the use of ICD codes leads to a significant underestimation (31%) of the true prevalence of heart failure. The third case study evaluates the consistency of diagnoses by comparing structured ICD-10-coded diagnoses with the diagnoses described in the diagnostic section of the discharge letter. These diagnoses are extracted from texts with ad hoc IE, using synonyms generated with a novel method. The developed approach can extract diagnoses from the discharge letter with a high accuracy and furthermore it can prove the degree of consistency between the coded and reported diagnoses.

An ad hoc1 network is defined as a decentralised wireless network that is set up on-the-fly for a specific purpose. These networks were proposed years ago for military use, with the purpose of communicating devices in a highly constrained scenario. Under such a network, devices join and leave the network dynamically; thus, it cannot be expected to have any kind of network infrastructure. This wish for decentralised on-the-fly networks has subsequently expanded to cover several fields besides the military. Today, there are several mobile services requiring the self-organising capabilities that ad hoc networks offer. Examples include packet tracking, online-gaming, and measuring systems, among others. Ad hoc networks have obvious benefits for mobile services, but they also introduce new issues that regular network protocols cannot cope with, including optimum routing, network fragmentation, reduced calculation power, energy-constrained terminals, etc. In ad hoc networks, positioning takes a significant role, mainly due to the on-the-fly condition. In fact, several services require nodes to know the position of the customers in order to perform their duty properly. Wireless sensor networks concentrate most of the services that need positioning to perform their duty. Such networks constitute a subset of ad hoc networks involving dense topologies operating in an ad hoc fashion, and they are composed of small, energy and computation constrained terminals. In ad hoc networks, and especially in wireless sensor networks, nodes are spread over a certain area without a precise knowledge about the topology. In fact, this topology is variable. Accordingly, there are several unknowns (e.g., node density and coverage, network’s energy map, the presence of shadowed zones, nodes’ placement in the network coverage area) that are likely to constrain the performance of ad hoc services. Knowledge of the terminals’ locations can substantially improve the service performance. Positioning is not only important for the service provisioning; it is also crucial in the ad hoc protocol stack development. Due to the changes in the topology and the lack of communication infrastructure, ad hoc protocols have to address several issues not present in regular cellular networks. Routing is one of the best examples of the dependence of ad hoc networks on positioning. Studies such as (Stojmenovic, 2002) demonstrate that only position-based routing protocols are scalable, i.e., able to cope with a higher density of

The Impact of the Ad Hoc Tribunals on the International Criminal Court

We study the capacity scaling laws for the cognitive network that consists of the primary hybrid network (PhN) and secondary ad hoc network (SaN). PhN is further comprised of an ad hoc network and a base station-based (BS-based) network. SaN and PhN are overlapping in the same deployment region, operate on the same spectrum, but are independent with each other in terms of communication requirements. The primary users (PUs), i.e., the ad hoc nodes in PhN, have the priority to access the spectrum. The secondary users (SUs), i.e., the ad hoc nodes in SaN, are equipped with cognitive radios, and have the functionalities to sense the idle spectrum and obtain the necessary information of primary nodes in PhN. We assume that PhN adopts one out of three classical types of strategies, i.e., pure ad hoc strategy, BS-based strategy, and hybrid strategy. We aim to directly derive multicast capacity for SaN to unify the unicast and broadcast capacities under two basic principles: 1) The throughput for PhN cannot be undermined in order sense due to the presence of SaN. 2) The protocol adopted by PhN does not alter in the interest of SaN, anyway. Depending on which type of strategy is adopted in PhN, we design the optimal-throughput strategy for SaN. We show that there exists a threshold of the density of SUs according to the density of PUs beyond which it can be proven that: 1) when PhN adopts the pure ad hoc strategy or hybrid strategy, SaN can achieve the multicast capacity of the same order as it is stand-alone; 2) when PhN adopts the BS-based strategy, SaN can asymptotically achieve the multicast capacity of the same order as if PhN were absent, if some specific conditions in terms of relations among the numbers of SUs, PUs, the destinations of each multicast session in SaN, and BSs in PhN hold.