Abhishek P. Patil

LANDMARC: indoor location sensing using active RFID

Growing convergence among mobile computing devices and embedded technology sparks the development and deployment of “context-aware” applications, where location is the most essential context. In this paper we present LANDMARC, a location sensing prototype system that uses Radio Frequency Identification (RFID) technology for locating objects inside buildings. The major advantage of LANDMARC is that it improves the overall accuracy of locating objects by utilizing the concept of reference tags. Based on experimental analysis, we demonstrate that active RFID is a viable and cost-effective candidate for indoor location sensing. Although RFID is not designed for indoor location sensing, we point out three major features that should be added to make RFID technologies competitive in this new and growing market.

Prioritized overlay multicast in mobile ad hoc environments

Many proposed routing protocols for manets require nodes to maintain and update complicated route information, which incurs significant overhead when groups have different priorities. To address this problem, some researchers have begun focusing on application-layer, or overlay, multicast in which an overlay network forms a virtual network consisting of only member nodes atop the physical infrastructure. We propose a prototype of prioritized overlay multicast for manets in which participating nodes can carry out multiple functions and thus be associated with more than one overlay tree.

Bluebot: Asset tracking via robotic location crawling

From manufacturers, distributors, and retailers of consumer goods to government departments, enterprises of all kinds are gearing up to use RFID technology to increase the visibility of goods and assets within their supply chain and on their premises. However, RFID technology alone lacks the capability to track the location of items once they are moved within a facility. We present a prototype automatic location sensing system that combines RFID technology and off-the-shelf Wi-Fi based continuous positioning technology for tracking RFID-tagged assets. Our prototype system employs a robot, with an attached RFID reader, which periodically surveys the space, associating items it detects with its own location determined with the Wi-Fi positioning system. We propose four algorithms that combine the detected tags reading with previous samples to refine its location. Our experiments have shown that our positioning algorithms can bring a two to three fold improvement over the positional accuracy limitations in both the RFID reader and the positioning technology.

BlueBot: asset tracking via robotic location crawling

From manufacturers, distributors, and retailers of consumer goods to government departments, enterprises of all kinds are gearing up to use RFID technology to increase the visibility of goods and assets within their supply chain and on their premises. However, RFID technology alone lacks the capability to track the location of items once they are moved within a facility. We present a prototype automatic location sensing system that combines RFID technology and off-the-shelf Wi-Fi based continuous positioning technology for tracking RFID-tagged assets. Our prototype system employs a robot, with an attached RFID reader, which periodically surveys the space, associating items it detects with its own location determined with the Wi-Fi positioning system. We propose four algorithms that combine the detected tags reading with previous samples to refine its location. Our experiments have shown that our positioning algorithms can bring a two to three fold improvement over the positional accuracy limitations in both the RFID reader and the positioning technology.

SOLONet: sub-optimal location-aided overlay network for MANETs

Overlay networks have made it easy to implement multicast functionality in MANETs. Their flexibility to adapt to different environments has helped in their steady growth. Overlay multicast trees that are built using location information account for node mobility and have a low latency. However, the performance gains of such trees are offset by the overhead involved in distributing and maintaining precise location information. As the degree of (location) accuracy increases, the performance improves but the overhead required to store and broadcast this information also increases. In this paper, we present SOLONet, a design to build a sub-optimal location aided overlay multicast tree, where location updates of each member node are event based. Unlike several other approaches, SOLONet doesn’t require every packet to carry location information or each node maintain location information of every other node or carrying out expensive location broadcast for each node. Our simulation results indicate that SOLONet is scalable and its sub-optimal tree performs very similar to an overlay tree built by using precise location information. SOLONet strikes a good balance between the advantages of using location information (for building efficient overlay multicast trees) versus the cost of maintaining and distributing location information of every member nodes.

Resource Allocation Using Multiple Edge-Sharing Multicast Trees

A typical multicast network consists of a single tree, in which only a few internal nodes contribute most resources and are involved in performing the multicast functionality. This leads to an uneven and inefficient utilization of network resources. The problem is more pronounced in mobile ad hoc networks (MANETs), where network resources are limited. One solution is to split the multicast content over a number of trees. This provides several paths for the multicast content and would involve more nodes in implementing multicast functionality. Although this approach improves network utilization, overall multicast latency increases. This paper presents a distributed algorithm to construct multiple edge-sharing trees (MESTs) for small group multicast. MESTs balance the resource allocation and delay constraints by choosing to overlap certain edges that have low weight. Simulation results show that MESTs can generate multicast networks that have low delays and fair resource utilization. MESTs are designed to work with any form of multicast in both wired and wireless networks.

A random walk based anonymous peer-to-peer protocol design

Anonymity has been one of the most challenging issues in Ad Hoc environment such as P2P systems. In this paper, we propose an anonymous protocol called Random Walk based Anonymous Protocol (RWAP), in decentralized P2P systems. We evaluate RWAP by comprehensive trace driven simulations. Results show that RWAP significantly reduces traffic cost and encryption overhead compared with existing approaches.

Resource allocation using multiple edge-sharing multicast trees

Implementing multicast in MANETs is a challenging task. A typical multicast network consists of a single tree, in which only a few internal nodes contribute most resources and are involved in performing the multicast functionality. This leads to an un-even utilization of network resources. This problem is more prominent in MANETs where network resources are limited. A possible solution to the problem is to split the multicast content over a number of trees. Multiple trees provide several paths for the multicast content and get more nodes involved in implementing the multicast functionality. However, in such a setup, not all the trees get to use the best weight edges, thus the overall multicast latency increases. This paper presents MEST, a distributed algorithm to construct multiple edge-sharing trees for small group multicast. MEST balances the resource allocation and delay constraints by choosing to overlap certain edges that have low weights. Our simulation results show that MEST is scalable and can generate multicast networks that have low delay and fair resource utilization

POMA: Prioritized Overlay Multicast in Ad Hoc Environments

Overlay Multicast networks in mobile ad-hoc environments have received much attention due to their increasing number of practical applications. In many applications, some participating nodes might be members of more than one overlay trees or may wish to build a temporary tree in order to perform certain important tasks. The priority of these trees can be defined by the importance of the service. For the success of such an application, it is necessary that nodes belonging to more than one tree are smart enough to ignore incoming messages from members in low priority trees while they are listening to members from a higher priority tree. In this paper, we present a prioritized overlay multicast in ad-hoc environments (POMA). POMA builds priority trees with certain nodes carrying important tasks in overlay networks, and rearranges low priority trees whenever some nodes temporarily move to a high priority network. We study the feasibility of POMA by identifying a suitable unicast routing protocol, exploring to use location information to build efficient trees, and studying the impact of density of wireless nodes to the system performance.

SOLONet: sub-optimal location-aided overlay network

Overlay networks have made it easy to implement multicast functionality in MANETs. Their flexibility to adapt to different environments has helped in their steady growth. Overlay multicast trees that are built using location information account for node mobility and have a low latency. However, the performance gains of such trees are offset by the overhead involved in distributing and maintaining precise location information. As the degree of (location) accuracy increases, the performance improves but the overhead required to store and broadcast this information also increases. In this paper, we present SOLONet, a design to build a sub-optimal location aided overlay multicast tree, where location updates of each member node are event based. Unlike several other approaches, SOLONet doesn’t require every packet to carry location information or each node maintain location information of every other node or carrying out expensive location broadcast for each node. Our simulation results indicate that SOLONet is scalable and its sub-optimal tree performs very similar to an overlay tree built by using precise location information. SOLONet strikes a good balance between the advantages of using location information (for building efficient overlay multicast trees) versus the cost of maintaining and distributing location information of every member nodes.