Results 1  10
of
191
Efficient routing in intermittently connected mobile networks: The multiplecopy case
, 2008
"... Intermittently connected mobile networks are wireless networks where most of the time there does not exist a complete path from the source to the destination. There are many real networks that follow this model, for example, wildlife tracking sensor networks, military networks, vehicular ad hoc net ..."
Abstract

Cited by 299 (18 self)
 Add to MetaCart
Intermittently connected mobile networks are wireless networks where most of the time there does not exist a complete path from the source to the destination. There are many real networks that follow this model, for example, wildlife tracking sensor networks, military networks, vehicular ad hoc networks, etc. In this context, conventional routing schemes fail, because they try to establish complete endtoend paths, before any data is sent. To deal with such networks researchers have suggested to use floodingbased routing schemes. While floodingbased schemes have a high probability of delivery, they waste a lot of energy and suffer from severe contention which can significantly degrade their performance. Furthermore, proposed efforts to reduce the overhead of floodingbased schemes have often been plagued by large delays. With this in mind, we introduce a new family of routing schemes that “spray ” a few message copies into the network, and then route each copy independently towards the destination. We show that, if carefully designed, spray routing not only performs significantly fewer transmissions per message, but also has lower average delivery delays than existing schemes; furthermore, it is highly scalable and retains good performance under a large range of scenarios. Finally, we use our theoretical framework proposed in our 2004 paper to analyze the performance of spray routing. We also use this theory to show how to choose the number of copies to be sprayed and how to optimally distribute these copies to relays.
Delay and Capacity Tradeoffs in Mobile Ad Hoc Networks: A Global Perspective
"... Since the original work of Grossglauser and Tse, which showed that the mobility can increase the capacity of an ad hoc network, there has been a lot of interest in characterizing the delaycapacity relationship in ad hoc networks. Various mobility models have been studied in the literature, and the ..."
Abstract

Cited by 147 (2 self)
 Add to MetaCart
(Show Context)
Since the original work of Grossglauser and Tse, which showed that the mobility can increase the capacity of an ad hoc network, there has been a lot of interest in characterizing the delaycapacity relationship in ad hoc networks. Various mobility models have been studied in the literature, and the delaycapacity relationships under those models have been characterized. The results indicate that there are tradeoffs between the delay and the capacity, and that the nature of these tradeoffs is strongly influenced by the choice of the mobility model. Some questions that arise are: (i) How representative are these mobility models studied in the lieterature? (ii) Can the delaycapacity relationship be significantly different under some other “reasonable ” mobility model? (iii) What would the delaycapacity tradeoff in a real network be like? In this paper, we address these questions. In particular, we analyze, among others, some of the mobility models that have been used in the recent related works, under a unified framework. We relate the nature of the delaycapacity tradeoff to the nature of the node motion, thereby providing a better understanding of the delaycapacity relationship in ad hoc networks than earlier works.
Peoplenet: engineering a wireless virtual social network
 in Proceedings of ACM MobiCom
, 2005
"... People often seek information by asking other people even when they have access to vast reservoirs of information such as the Internet and libraries. This is because people are great sources of unique information, especially that which is locationspecific, communityspecific and timespecific. Soci ..."
Abstract

Cited by 122 (2 self)
 Add to MetaCart
(Show Context)
People often seek information by asking other people even when they have access to vast reservoirs of information such as the Internet and libraries. This is because people are great sources of unique information, especially that which is locationspecific, communityspecific and timespecific. Social networking is effective because this type of information is often not easily available anywhere else. In this paper, we conceive a wireless virtual social network which mimics the way people seek information via social networking. PeopleNet is a simple, scalable and lowcost architecture for efficient information search in a distributed manner. It uses the infrastructure to propagate queries of a given type to users in specific geographic locations, called bazaars. Within each bazaar, the query is further propagated between neighboring nodes via peertopeer connectivity until it finds a matching
Broadcast capacity in multihop wireless networks
 In MobiCom
, 2006
"... Abstract — In this paper we study the broadcast capacity of multihop wireless networks which we define as the maximum rate at which broadcast packets can be generated in the network such that all nodes receive the packets successfully within a given time. To asses the impact of topology and interfer ..."
Abstract

Cited by 106 (5 self)
 Add to MetaCart
Abstract — In this paper we study the broadcast capacity of multihop wireless networks which we define as the maximum rate at which broadcast packets can be generated in the network such that all nodes receive the packets successfully within a given time. To asses the impact of topology and interference on the broadcast capacity we employ the Physical Model and Generalized Physical Model for the channel. Prior work was limited either by density constraints or by using the less realistic but manageable Protocol model [1], [2]. Under the Physical Model, we find that the broadcast capacity is within a constant factor of the channel capacity for a wide class of network topologies. Under the Generalized Physical Model, on the other hand, the network configuration is divided into three regimes depending on how the power is tuned in relation to network density and size and in which the broadcast capacity is asymptotically either zero, constant or unbounded. As we show, the broadcast capacity is limited by distant nodes in the first regime and by interference in the second regime. In the second regime, which covers a wide class of networks, the broadcast capacity is within a constant factor of the bandwidth. I.
ContentionAware Performance Analysis of MobilityAssisted Routing
 IEEE TRANSACTIONS ON MOBILE COMPUTING (UNDER SUBMISSION)
"... A large body of work has theoretically analyzed the performance of mobilityassisted routing schemes for intermittently connected mobile networks. However, the vast majority of these prior studies have ignored wireless contention. Recent papers have shown through simulations that ignoring contention ..."
Abstract

Cited by 96 (7 self)
 Add to MetaCart
A large body of work has theoretically analyzed the performance of mobilityassisted routing schemes for intermittently connected mobile networks. However, the vast majority of these prior studies have ignored wireless contention. Recent papers have shown through simulations that ignoring contention leads to inaccurate and misleading results, even for sparse networks. In this paper, we analyze the performance of routing schemes under contention. First, we introduce a mathematical framework to model contention. This framework can be used to analyze any routing scheme with any mobility and channel model. Then, we use this framework to compute the expected delays for different representative mobilityassisted routing schemes under random direction, random waypoint and communitybased mobility models. Finally, we use these delay expressions to optimize the design of routing schemes while demonstrating that designing and optimizing routing schemes using analytical expressions which ignore contention can lead to suboptimal or even erroneous behavior.
Optimal ThroughputDelay Scaling in Wireless Networks  Part I: The Fluid Model
"... Gupta and Kumar (2000) introduced a random model to study throughput scaling in a wireless network with static nodes, and showed that the throughput per sourcedestination pair is Θ ( 1 / √ n log n). Grossglauser and Tse (2001) showed that when nodes are mobile it is possible to have a constant thr ..."
Abstract

Cited by 79 (2 self)
 Add to MetaCart
(Show Context)
Gupta and Kumar (2000) introduced a random model to study throughput scaling in a wireless network with static nodes, and showed that the throughput per sourcedestination pair is Θ ( 1 / √ n log n). Grossglauser and Tse (2001) showed that when nodes are mobile it is possible to have a constant throughput scaling per sourcedestination pair. In most applications delay is also a key metric of network performance. It is expected that high throughput is achieved at the cost of high delay and that one can be improved at the cost of the other. The focus of this paper is on studying this tradeoff for wireless networks in a general framework. Optimal throughputdelay scaling laws for static and mobile wireless networks are established. For static networks, it is shown that the optimal throughputdelay tradeoff is given by D(n) = Θ(nT (n)), where T (n) and D(n) are the throughput and delay scaling, respectively. For mobile networks, a simple proof of the throughput scaling of Θ(1) for the GrossglauserTse scheme is given and the associated delay scaling is shown to be Θ(n log n). The optimal throughputdelay tradeoff for mobile networks is also established. To capture physical movement in the real world, a random walk model for node mobility is assumed. It is shown that for throughput of O ( 1 / √ n log n) , which can also be achieved in static networks, the throughputdelay tradeoff is the same as in static networks, i.e., D(n) = Θ(nT (n)). Surprisingly, for almost any throughput of a higher order, the delay is shown to be Θ(n log n), which is the delay for throughput of Θ(1). Our result, thus, suggests that the use of mobility to increase throughput, even slightly, in realworld networks would necessitate an abrupt and very large increase in delay.
Degenerate DelayCapacity Tradeoffs in AdHoc Networks with Brownian Mobility
 IEEE/ACM Trans. Netw
, 2006
"... Abstract — There has been significant recent interest within the networking research community to characterize the impact of mobility on the capacity and delay in mobile ad hoc networks. In this paper, we study the fundamental tradeoff between the capacity and delay for a mobile ad hoc network unde ..."
Abstract

Cited by 67 (3 self)
 Add to MetaCart
(Show Context)
Abstract — There has been significant recent interest within the networking research community to characterize the impact of mobility on the capacity and delay in mobile ad hoc networks. In this paper, we study the fundamental tradeoff between the capacity and delay for a mobile ad hoc network under the Brownian motion model. We show that the 2hop relaying scheme proposed by Grossglauser and Tse (2001), while capable of achieving Θ(1) pernode capacity, incurs an expected packet delay of Ω(log n/σ 2 n), where σ 2 n is the variance parameter of the Brownian motion model. We then show that in order to reduce the delay by any significant amount, one must be ready to accept a pernode capacity close to static ad hoc networks. In particular, we show that under a large class of scheduling and relaying schemes, if the mean packet delay is O(n α /σ 2 n), for any α < 0, then the pernode capacity must be O(1 / √ n). This result is in sharp contrast to other results that have recently been reported in the literature. I.
The fundamental capacitydelay tradeoff in large mobile ad hoc networks
 In Third Annual Mediterranean Ad Hoc Networking Workshop
, 2004
"... Abstract — There has been recent interest within the networking research community to understand how mobility can improve the capacity of mobile ad hoc networks. Of particular interest is the achievable capacity under delay constraints. In this paper, we establish the following upper bound on the op ..."
Abstract

Cited by 59 (4 self)
 Add to MetaCart
(Show Context)
Abstract — There has been recent interest within the networking research community to understand how mobility can improve the capacity of mobile ad hoc networks. Of particular interest is the achievable capacity under delay constraints. In this paper, we establish the following upper bound on the optimal capacitydelay tradeoff in mobile ad hoc networks for an i.i.d. mobility model. For a mobile ad hoc network with n nodes, if the perbitaveraged mean delay is bounded by ¯ D, then the pernode capacity λ is upper bounded by λ3 ≤ O ( ¯ D n log3 n). By studying the condition under which the upper bound is tight, we are able to identify the optimal values of several key scheduling parameters. We then develop a new scheme that can achieve a capacitydelay tradeoff close to the upper bound up to a logarithmic factor. Our new scheme achieves a larger pernode capacity than the schemes reported in previous works. In particular, when the delay is bounded by a constant, our scheme achieves a pernode capacity of Θ(n−1/3 / log n). This indicates that, for the i.i.d. mobility model, mobility results in a larger capacity than that of static networks even with constant delays. Finally, the insight drawn from the upper bound allows us to identify limiting factors in existing schemes. These results present a relatively complete picture of the achievable capacitydelay tradeoffs under different settings. I.
The multicast capacity of large multihop wireless networks
 In Proc. of ACM MobiHoc ’07
, 2007
"... We consider wireless ad hoc networks with a large number of users. Subsets of users might be interested in identical information, and so we have a regime in which several multicast sessions may coexist. We first calculate an upperbound on the achievable transmission rate per multicast flow as a fun ..."
Abstract

Cited by 52 (2 self)
 Add to MetaCart
We consider wireless ad hoc networks with a large number of users. Subsets of users might be interested in identical information, and so we have a regime in which several multicast sessions may coexist. We first calculate an upperbound on the achievable transmission rate per multicast flow as a function of the number of multicast sources in such a network. We then propose a simple combbased architecture for multicast routing which achieves the upper bound in an order sense under certain constraints. Compared to the approach of constructing a Steiner tree to decide multicast paths, our construction achieves the same orderoptimal results while requiring little location information and no computational overhead.
Delay and Capacity Tradeoffs for Wireless Ad Hoc Networks with Random Mobility
, 2005
"... In this paper, we study the delay and capacity tradeoffs for wireless ad hoc networks with random mobility. We consider some simple distributed scheduling and relaying protocols that are motivated by the 2hop relaying protocol proposed by Grossglauser and Tse (2001). We consider a model in which t ..."
Abstract

Cited by 39 (4 self)
 Add to MetaCart
(Show Context)
In this paper, we study the delay and capacity tradeoffs for wireless ad hoc networks with random mobility. We consider some simple distributed scheduling and relaying protocols that are motivated by the 2hop relaying protocol proposed by Grossglauser and Tse (2001). We consider a model in which the nodes are placed uniformly on a sphere, and move in accordance with an i.i.d. mobility model. We consider two i.i.d mobility models: Brownian mobility model and random waypoint mobility model. We show that under a distributed GrossglauserTse 2hop relaying protocol, the delay scales as &Theta;(T_p(n)n) for random waypoint mobility model, and O(T_p(n)log&sup2;n) for Brownian mobility model, where T_p(n) is the transmission time of the packet. In the case, where only nearest neighbor transmissions are allowed, the delay is shown to scale as &Omega(T_p(n)&radic;n), for all possible scheduling and relaying protocols. In the case of random waypoint mobility model, we show that delay/capacity &ge; &Theta;(T_p(n)n) is a necessary tradeoff. Two protocols which achieve the lower bound of &Theta;(T_p(n)n) are considered, and their relative performance in terms of delay/capacity tradeoff is established. Our results indicate that significant improvement in the delay can be achieved by reducing the packet size, at high node speeds.