Transcatheter tricuspid valve replacement (TTVR) has emerged as a promising minimally invasive procedure for treating severe tricuspid regurgitation (TR). However, accurate catheter delivery remains a significant challenge, primarily due to the reliance on 2D vision feedback, complex catheter kinematics, camera-to-robot pose calibration, which are difficult to generalize across patients. To address these issues, this paper presents a model-free robotic catheter delivery strategy for TTVR using Data-Enabled Predictive Control (DeePC). This approach leverages data-driven control to optimize catheter positioning without the need for prior knowledge of the system’s dynamics, eliminating the need for complex kinematic models or camera calibration. The proposed method incorporates environmental constraints to ensure the safety of the procedure, delivering the catheter to the desired location with high accuracy across varying catheters and camera poses. Experimental results demonstrate the effectiveness and versatility of the approach, suggesting its potential for broader applications in robotic-assisted surgeries. This work presents a new perspective for vision based robotic TTVR, as well as other clinical interventions involving robotic catheter control.

Abstract In this paper, we study the two‐tiered wireless sensor network (WSN) architecture and propose the optimal cluster association algorithm for it to maximize the overall network lifetime. A two‐tiered WSN is formed by number of small sensor nodes (SNs), powerful application nodes (ANs), and base‐stations (BSs, or gateways). SNs capture, encode, and transmit relevant information to ANs, which then send the combined information to BSs. Assuming the locations of the SNs, ANs, and BSs are fixed, we consider how to associate the SNs to ANs such that the network lifetime is maximized while every node meets its bandwidth requirement. When the SNs are homogeneous (e.g., same bandwidth requirement), we give optimal algorithms to maximize the lifetime of the WSNs; when the SNs are heterogeneous, we give a 2‐approximation algorithm that produces a network whose lifetime is within 1/2 of the optimum. We also present algorithms to dynamically update the cluster association when the network topology changes. Numerical results are given to demonstrate the efficiency and optimality of the proposed approaches. In simulation study, comparing network lifetime, our algorithm outperforms other heuristics almost twice. Copyright © 2007 John Wiley & Sons, Ltd.

Conventionally, most network protocols assume that the network entities who participate in the network activities will always behave as instructed. However, in practice, most network entities are selfish: they will try to maximize their own benefits instead of altruistically contributing to the network by following the prescribed protocols. Thus, new protocols should be designed for the non-cooperative network that is composed of selfish entities. In this paper, we specifically show how to design truthful multicast protocols for non-cooperative networks such that these selfish entities will follow the protocols out of their own interests. By assuming that every entity has a fixed cost for a specific multicast, we give a general framework to decide whether it is possible and how, if possible, to transform an existing multicast protocol to a truthful multicast protocol by designing a proper payment protocol. We then show how the payments to those relay entities are shared fairly among all receivers so that it encourages collaboration among receivers. As running examples, we show how to design truthful multicast protocols for several multicast structures that are currently used in practice.

We study efficient interference-aware joint routing and TDMA link scheduling for a multihop wireless network to maximize its throughput. Efficient link scheduling can greatly reduce the interference effect of close-by transmissions. Unlike the previous studies that often assume a unit disk graph model, we assume that different terminals could have different transmission ranges and interference ranges. In our model, a communication link may not exist due to barriers or is not used by a predetermined routing protocol. Using a mathematical formulation, we develop interference aware joint routing and TDMA link schedulings that optimize the networking throughput subject to various constraints. Our linear programming formulation will find a flow routing whose achieved throughput (or fairness) is at least a constant fraction of the optimum. Then, by assuming known link capacities and link traffic loads, we study link scheduling under the RTS/CTS interference model and the protocol interference model with fixed transmission power. For both models, we present both efficient centralized and distributed algorithms that use time slots within a constant factor of the optimum. We also present efficient distributed algorithms whose performances are still comparable with optimum, but with much less communications. Our theoretical results are corroborated by extensive simulation studies.

We propose novel solutions for unicast routing in wireless networks consisted of selfish terminals: in order to alleviate the inevitable over-payment problem (and thus economic inefficiency) of the VCG (Vickrey-Clark-Groves) mechanism, we design a mechanism that results in Nash equilibria rather than the traditional strate-gyproofness (using weakly dominant strategy). In addition, we systematically study the unicast routing system in which both the relay terminals and the service requestor (either the source or the destination nodes or both) could be selfish. To the best of our knowledge, this is the first paper that presents social efficient unicast routing systems with proved performance guarantee. Thus, we call the proposed systems: Optimal Unicast Routing Systems (OURS).Our main contributions of OURS are as follows. (1) For the principal model where the service requestor is not selfish, we propose a mechanism that provably creates incentives for intermediate terminals to cooperate in forwarding packets for others. Our mechanism substantially reduces the overpayment by using Nash equilibrium solutions as opposed to strategyproof solutions. We then study a more realistic case where the service requestor can act selfishly. (2) We first show that if we insist on the requirement of strategyproofness for the relay terminals, then no system can guarantee that the central authority can retrieve at least 1overn of the total payment. (3) We then present a strategyproof unicast system that collects 1over2n of the total payment, which is thus asymptotically optimum. (4) By only requiring Nash Equilibrium solutions, we propose a system that creates incentives for the service requestor and intermediate terminals to correctly follow the prescribed protocol. More importantly, the central authority can retrieve at least half the total payment. We verify the economic efficiency of our systems through simulations that are based on very realistic terminal distributions.

We study efficient link scheduling for a multihop wireless network to maximize its throughput. Efficient link scheduling can greatly reduce the interference effect of close-by transmissions. Unlike the previous studies that often assume a unit disk graph model, we assume that different terminals could have different transmission ranges and different interference ranges. In our model, it is also possible that a communication link may not exist due to barriers or is not used by a predetermined routing protocol, while the transmission of a node always result interference to all non-intended receivers within its interference range. Using a mathematical formulation, we develop synchronized TDMA link schedulings that optimize the networking throughput. Specifically, by assuming known link capacities and link traffic loads, we study link scheduling under the RTS/CTS interference model and the protocol interference model with fixed transmission power. For both models, we present both efficient centralized and distributed algorithms that use time slots within a constant factor of the optimum. We also present efficient distributed algorithms whose performances are still comparable with optimum, but with much less communications. Our theoretical results are corroborated by extensive simulation studies.

Smart antennas have gained significant importance in multi-hop wireless networks in recent years, because of their sophisticated signal processing capabilities that hold the potential for increased data rates and reliability. In this work, we consider the problem of communication in multi-hop wireless networks with smart antennas (specifically digital adaptive arrays). These smart antennas provide degrees of freedom (DOFs) that can be used to suppress co-existing communication links, thereby increasing spatial reuse in the network. Thus, the communication problem comprises of not just determining a channel access mechanism to be used by the communication links, but also involves the determination of the communication pattern (usage of DOFs) to be used by each node during channel access. To the best of our knowledge, our work is the first step towards addressing this problem.We first consider the problem of determining the communication pattern to be used by the nodes and formulate it combinatorially with the goal of optimizing network performance through interference minimization. We present efficient centralized and distributed algorithms that are within a factor of ¾ and ½ of the optimum solution respectively. We then extend the distributed algorithm to incorporate TDMA-based scheduling in a purely localized manner. The distributed algorithms are then evaluated through simulations in ns2 and insights are drawn into the potential performance benefits of smart antennas in multi-hop wireless networks.

In this paper, we address the problem of energy efficient localized routing in wireless ad hoc networks. Numerous energy aware routing protocols were proposed to seek the power efficiency of routes. Among them, several geographical localized routing protocols were proposed to help making smarter routing decision using only local information and reduce the routing overhead. However, most of the proposed localized routing methods cannot theoretically guarantee the power efficiency of their routes. In this paper, we give the first localized routing algorithm, called localized energy aware restricted neighborhood routing (LEARN), which can guarantee the power efficiency of its route asymptotically almost sure. Given destination node t, an intermediate node v will only select a certain neighbor v such thatvutles alpha for a parameter alphan= radicbetalnl/pin for some beta > pi/alpha, our LEARN routing protocol will find the route for any pair of nodes asymptotically almost sure. When the transmission range rn= radicbetalnl/pin for some beta < pi/alpha, the LEARN routing protocol will not be able to find the route for any pair of nodes asymptotically almost sure. We also conducted simulations to study the performance of LEARN and compare it with a typical localized routing protocol (GPSR) and a global ad hoc routing protocol (DSR)

Differentiated service (DiffServ) is a mechanism to provide the quality-of-service (QoS) with a certain performance guarantee. In this paper, we study how to design DiffServ multicast when every relay link is an independent selfish agent. We assume that each link e/sub i/ is associated with a (privately known) cost coefficient c/sub i/ such that the cost of e/sub i/ to provide a transmission service with bandwidth demand x is c/sub i//spl middot/x. Further, we assume that there is a fixed source node s and a set R of receivers, each of which requires from s data with a minimum bandwidth demand. The DiffServ multicast problem is to compute a link-weighted tree rooted at s and spanning R such that the receivers' demands are met. This generalizes the traditional link-weighted Steiner tree problem. We first show that a previous approximation algorithm does not directly induce a strategyproof mechanism. We then give a new polynomial time algorithm to construct a DiffServ multicast tree whose total cost is no more than eight times the optimal total cost when the cost coefficient of each link is known. Based on this tree, we design a truthful mechanism for DiffServ multicast, i.e., we give a polynomial-time computable payment scheme to compensate all chosen relay links such that each link maximizes its profit when it declares its cost coefficient truthfully.

Numerous routing protocols have been proposed for wireless networks. A common assumption made by the majority of these protocols is that each wireless node will follow the prescribed protocol without any deviation. This may not be true in practice since wireless nodes could be owned by users who perform in their own interests. We then have to design routing protocols that still work properly even for networks composed of selfish nodes. In this paper, we propose a unicast routing protocol to address this issue under the assumption that all networking nodes are rational. Here, a node is rational if it always chooses a strategy that maximizes its benefit. We assume that each node has a privately known cost of relaying a unit of data for other nodes. In our protocol, each wireless node has to declare a cost for forwarding a unit of data. When a node wants to send data to the access point, it first computes the least cost path to the access point and then computes a payment to each node on this path. We present a pricing mechanism such that the profit of each relay node is maximized when it declares its true cost. We also give a time optimal method to compute the payment in a centralized manner. We then discuss in detail how to implement the routing protocol in the distributed manner. We conduct extensive simulations to study the ratio of the total payment over the total cost incurred by all relay nodes. We find that this ratio is small in practice. Our protocol works when the wireless nodes will not collude and we show that no truthful mechanism can avoid the collusion of any pair of two nodes. We also give a truthful mechanism when a node only colludes with its neighbors.

We propose a novel localized topology-control algorithm for each wireless node to locally select communication neighbors and adjust its transmission power accordingly such that all nodes together self-form a topology that is energy efficient simultaneously for both unicast and broadcast communications. We theoretically prove that the proposed topology is planar, which meets the requirement of certain localized routing methods to guarantee packet delivery; it is power-efficient for unicast - the energy needed to connect any pair of nodes is within a small constant factor of the minimum; it is also asymptotically optimum for broadcast - the energy consumption for broadcasting data on top of it is asymptotically the best among all structures constructed using only local information; it has a constant bounded logical degree, which will potentially save the cost of updating routing tables if used. We further prove that the expected average physical degree of all nodes is a small constant. To the best of our knowledge, this is the first localized topology-control strategy for all nodes to maintain a structure with all these desirable properties. Previously, only a centralized algorithm was reported. Moreover, by assuming that the node ID and its position can be represented in O(log n) bits for a wireless network of n nodes, the total number of messages by our methods is in the range of theoretical results are corroborated in the simulations.

Backbone has been used extensively in various aspects (e.g., routing, route maintenance, broadcast, scheduling) for wireless ad hoc or sensor networks recently. Previous methods are mostly designed to minimize the size of the backbone. However, in many applications, it is desirable to construct a backbone with small cost when each wireless node has a cost of being in the backbone. In this paper, we first show that previous methods specifically designed to minimize the backbone size may produce a backbone with large cost. Then, an efficient distributed method to construct a weighted backbone with low cost is proposed. We prove that the total cost of the constructed backbone is within a small constant factor of the optimum for homogeneous networks when either the nodes' costs are smooth (i.e., the maximum ratio of costs of adjacent nodes is bounded) or the network maximum node degree is bounded. We also show that, with a small modification, the backbone is efficient for unicast: the total cost (or hop) of the least cost (or hop) path connecting any two nodes using backbone is no more than three (or four) times the least cost (or hop) path in the original communication graph. Our theoretical. results are corroborated by our simulation studies. Finally, we discuss several possible ad hoc network applications of our proposed backbone formation algorithms.

Wireless hybrid networks combine the characteristics of both cellular and mobile ad hoc networks. In wireless hybrid networks, it is often assumed that each individual mobile node faithfully follows the prescribed protocols without any deviation. However, these mobile devices, when owned by individual users, will likely do what is the most beneficial to their owners, i.e., act "selfishly". Therefore, an algorithm or protocol intended for selfish wireless devices must be designed. In this paper, we specifically study how to design routing protocols in wireless hybrid networks with selfish nodes. We first present a VCG-based routing protocol for hybrid networks, and show it is truthful but could be expensive. Then we modify the VCG-based routing protocol to make it more efficient for hybrid networks in term of total payment. However, we prove that nodes could lie up their costs in the modified method. Moreover, we propose a novel routing protocol based on first-price path auctions [N. Immorlica et al, 2005], which can achieve a Nash equilibrium with low total payment.

Conventionally, most network protocols assume that the network entities that participate in the network activities will always behave as instructed. However, in practice, most network entities will try to maximize their own benefits instead of altruistically contribute to the network by following the prescribed protocols, which is known as selfish. Thus, new protocols should be designed for the non-cooperative network, which is composed of selfish entities. In this paper, we specifically show how to design strategyproof multicast protocols for non-cooperative networks such that these selfish entities will follow the protocols out of their own interests. By assuming that a group of receivers is willing to pay to receive the multicast service, we specifically give a general framework to decide whether it is possible, and how if possible to transform an existing multicast protocol to a strategyproof multicast protocol. We then show how the payments to those relay entities are shared fairly among all receivers so that it encourages collaboration among receivers. As a running example, we show how to design the strategyproof multicast protocol for the currently used core-based multicast structure. We also conduct extensive simulations to study the relations between payment and cost of the multicast structure.

We propose a novel communication efficient topology control algorithm for each wireless node to select communication neighbors and adjust its transmission power, such that all nodes together self-form a topology that is energy efficient simultaneously for both unicast and broadcast communications. We prove that the proposed topology is planar, which guarantees packet delivery if a certain localized routing method is used; it is power efficient for unicast-- the energy needed to connect any pair of nodes is within a small constant factor of the minimum under a common power attenuation model; it is efficient for broadcast: the energy consumption for broadcasting data on top of it is asymptotically the best compared with structures constructed locally; it has a constant bounded logical degree, which will potentially reduce interference and signal contention. We further prove that the average physical degree of all nodes is bounded by a small constant. To the best of our knowledge, this is the first communication-efficient distributed algorithm to achieve all these properties. Previously, only a centralized algorithm was reported in [3]. Moreover, by assuming that the ID and position of every node can be represented in O(log n) bits for a wireless network of n nodes, our method uses at most 13n messages, where each message is of O(log n) bits. We also show that this structure can be efficiently updated for dynamical network environment. Our theoretical results are corroborated in the simulations.

Backbone has been used extensively in various aspects (e.g., routing, route maintenance, broadcast, scheduling) for wireless networks. Previous methods are mostly designed to minimize the backbone size. However, in many applications, it is desirable to construct a backbone with small cost when each wireless node has a cost of being in the backbone. In this paper, we first show that previous methods specifically designed to minimize the backbone size may produce a backbone with a large cost. We then propose an efficient distributed method to construct a weighted sparse backbone with low cost. We prove that the total cost of the constructed backbone is within a small constant factor of the optimum for homogeneous networks when either the nodes' costs are smooth or the network maximum node degree is bounded. We also show that with a small modification the constructed backbone is efficient for unicast: the total cost (or hop) of the least cost (or hop) path connecting any two nodes using backbone is no more than 3 (or 4) times of the least cost (or hop) path in the original communication graph. As a side product, we give an efficient overlay based multicast structure whose total cost is no more than 10 times of the minimum when the network is modeled by UDG. Our theoretical results are corroborated by our simulation studies.

Abstract — Topology control has been well studied in wireless ad hoc networks. However, only a few topology control methods (e.g. [1]) take into account the low interference as a goal of the methods. Some researchers tried to indirectly reduce the interference by reducing the transmission power or by devising low degree topologies, but none of those protocols can guarantee low interference. In this paper we present several algorithms to construct network topologies such that the maximum (or average) link (or nodal) interference of the topology is either minimized or approximately minimized. The algorithms and definitions introduced in this paper are not based on any geometry information about the nodes and they work for any graph models of wireless communication. The theoretical results are corroborated by simulation studies. I.

The family of Vickrey-Clarke-Groves (VCG) mechanisms is arguably the most celebrated achievement in truthful mechanism design. However, VCG mechanisms have their limitations. They only apply to optimization problems with a utilitarian (or affine) objective function, and their output should optimize the objective function. For many optimization problems, finding the optimal output is computationally intractable. If we apply VCG mechanisms to polynomial-time algorithms that approximate the optimal solution, the resulting mechanisms may no longer be truthful.In light of these limitations, it is useful to study whether we can design a truthful non-VCG payment scheme that is computationally tractable for a given allocation rule O. In this paper, we focus our attention on emphbinary demand games in which the agents' only available actions are to take part in the a game or not to. For these problems, we prove that a truthful mechanism M=(O, P) exists with a proper payment method P iff the allocation rule O satisfies a certain monotonicity property. We provide a general framework to design such P. We further propose several general composition-based techniques to compute P efficiently for various types of output. In particular, we show how P can be computed through "or/and" combinations, round-based combinations, and some more complex combinations of the outputs from subgames.

Conventionally, the majority of network routing protocols assume that every network terminal or link forwards data for others without any deviation. However, this may not be true when the terminals or links are owned by individual selfish users, who always tries to maximize their own benefits instead of faithfully following a prescribed protocol. We propose a new routing protocol, called k-anycast routing, that works well even if network links (or terminals or both) are selfish. In our protocol, the source node first finds a tree that spans k receivers out of a set of possible receivers and pay the relay links to compensate their costs. We prove that every relay link follows the routing protocol: it maximizes its profit when it declares its actual cost.

Summary form only given. Many of the existing works in wireless networks assumes that individual wireless node (possibly owned by selfish users) will follow prescribed protocols without deviation. We address the issue of user cooperation in selfish and rational wireless networks using an incentive approach. We first present a strategy-proof pricing mechanism for the unicast problem and give a time optimal method to compute the payment in a centralized manner. We then discuss in detail how to implement the algorithm in the distributed manner. We conduct extensive simulations to study the relation of the total payment of a node to the total cost of all relay nodes and found out the ratio of the total payment over the total cost is small. Our protocol works when the wireless nodes will not collude and we show that no truthful mechanism can avoid the collusion between arbitrary two nodes. We also give truthful mechanism when a node only colludes with its neighbors.

It is conventionally assumed that all wireless devices will follow the prescribed routing protocols without any deviation. However, the scarcity of resources in wireless devices raises a concern about this assumption. Most often, instead of faithfully following the protocols, the owners of wireless devices will try to manipulate the protocols for their own benefits. We specifically study the multicast in selfish and rational wireless ad hoc networks. By assuming that each wireless node has a private cost of forwarding data for other nodes, we first give an efficient method to construct a multicast tree, namely VMST, whose cost is a 5-approximation of the optimum multicast tree's cost for homogeneous wireless networks. We then design a truthful payment scheme that pays minimum for any relay node among all truthful payment schemes based on VMST.

In wireless networks, it is often assumed that each individual wireless terminal will faithfully follow the prescribed protocols without any deviation-- except, perhaps, for a few faulty or malicious ones. Wireless terminals, when owned by individual users, will likely do what is the most beneficial to their owners, i.e., act "selfishly". Therefore, an algorithm or protocol intended for selfish wireless networks must be designed.In this paper, we specifically study how to conduct efficient multicast routing in selfish wireless networks. We assume that each wireless terminal or communication link will incur a cost when it transits some data. Traditionally, the VCG mechanism has been the only method to design protocols so that each selfish agent will follow the protocols for its own interest to maximize its benefit. The main contributions of this paper are two-folds. First, for each of the widely used multicast structures, we show that the VCG based mechanism does not guarantee that the selfish terminals will follow the protocol. Second, we design the first multicast protocols without using VCG mechanism such that each agent maximizes its profit when it truthfully reports its cost.Extensive simulations are conducted to study the practical performances of the proposed protocols regarding the actual network cost and total payment.