CiteULike: erl's library [22 articles]

Providing full connectivity in large ad-hoc networks by dynamic placement of aerial platforms

K Chandrashekar — 2007-11-10T20:47:35-00:00

Military Communications Conference, 2004. MILCOM 2004. IEEE, Vol. 3 (2004), pp. 1429-1436 Vol. 3.

In this paper we address the problem of providing full connectivity to disconnected ground MANET nodes by dynamically placing unmanned aerial vehicles (UAVs) to act as relay nodes. We provide a heuristic algorithm to find the minimal number of such aerial vehicles required to provide fall connectivity and find the corresponding locations for these aerial platforms (UAVs). We also track the movement of the ground nodes and update the location of the UAVs. We describe a communication framework that enables the ground nodes to communicate with its peer ground nodes as well as the UAVs that act as relay nodes. The communication architecture is designed to work with existing MANET routing protocols.

Capacity of Ad Hoc wireless networks

Jinyang Li — 2005-09-28T00:13:46-00:00

(2001), pp. 61-69.

Throughput capacity of random ad hoc networks with infrastructure support

Ula? Kozat — 2005-11-09T00:19:57-00:00

(2003), pp. 55-65.

A Survey of Mobility Models for Ad Hoc Network Research

T Camp — 2006-06-26T09:49:38-00:00

Wireless Communications & Mobile Computing (WCMC): Special issue on Mobile Ad Hoc Networking: Research, Trends and Applications, Vol. 2, No. 5. (2002), pp. 483-502.

In the performance evaluation of a protocol for an ad hoc network, the protocol should be tested under realistic conditions including, but not limited to, a sensible transmission range, limited buffer space for the storage of messages, representative data traffic models, and realistic movements of the mobile users (i.e., a mobility model). This paper is a survey of mobility models that are used in the simulations of ad hoc networks. We describe several mobility models that represent mobile...

An analysis of the optimum node density for ad hoc mobile networks

EM Royer — 2007-10-03T11:27:31-00:00

Communications, 2001. ICC 2001. IEEE International Conference on, Vol. 3 (2001), pp. 857-861 vol.3.

An ad hoc mobile network is a collection of nodes, each of which communicates over wireless channels and is capable of movement. Wireless nodes have the unique capability of transmission at different power levels. As the transmission power is varied, a tradeoff exists between the number of hops from source to destination and the overall bandwidth available to individual nodes. Because both battery life and channel bandwidth are limited resources in mobile networks, it is important to ascertain the effects different transmission powers have on the overall performance of the network. This paper explores the nature of this transmission power tradeoff in mobile networks to determine the optimum node density for delivering the maximum number of data packets. It is shown that there does not exist a global optimum density, but rather that, to achieve this maximum, the node density should increase as the rate of node movement increases

A study into the practical issues related to a deployed ad hoc wireless sensor network

EL Kuan — 2007-10-03T09:31:57-00:00

Wireless Communications and Networking Conference, 2005 IEEE, Vol. 4 (2005), pp. 1952-1957 Vol. 4.

This paper investigates the practical issues related to the energy efficiency of a deployed wireless sensor network through the use of network simulations. The IEEE 802.11b standard is used as the communications technology and the dynamic source routing algorithm provides the mechanism for generating the communications routes from data sources to data sinks. The study looks into the optimal position for a gateway node in a deployed network and also investigates methods of distributing the network load evenly across the network.

Positioning range extension gateways in mobile ad hoc wireless networks to improve connectivity and throughput

M Ahmed — 2007-10-02T10:57:20-00:00

Military Communications Conference, 2001. MILCOM 2001. Communications for Network-Centric Operations: Creating the Information Force. IEEE, Vol. 1 (2001), pp. 331-335 vol.1.

The dynamic nature of a mobile ad hoc network (MANET) may result in a cluster of nodes being isolated from the remaining network, especially when deployed in a terrain with blockages. In order to facilitate scalability and to provide connectivity between partitions that might occur in wireless networks as a consequence of mobility, we can envision a 'range extension' network that consists of airborne communication platforms, or geostationary/low-Earth-orbit satellites. These airborne/satellite nodes maintain communication links with specific 'gateway' nodes among the mobile ground nodes. To communicate with a node that is geographically distant or belongs to a different network partition, an ad hoc node can relay its data packets through an appropriate mobile gateway and via the range extension network. If we envision that the MANET is divided into different groups and a mobile gateway is deployed for each such group, an objective then is to determine the trajectory of the mobile gateway to best serve the ad hoc group to which it belongs, in terms of network performance metrics such as throughput and latency. In this paper, this problem of computing the optimal position for a gateway is reduced to a linear optimization problem by means of some simplifying but realistic assumptions. We suggest methods that may be deployed to enable the gateway to follow this optimal trajectory as closely as possible (within the practical constraints imposed by its velocity and maneuverability). Simulation results for various scenarios show a 10-15% improvement in the throughput and latency, per gateway domain, if a gateway has a dynamic trajectory whose locus follows the computed optimal position, as compared to a gateway that is statically placed at a regular position, or to a gateway that has a random trajectory.

An architecture for providing range extension by deploying mobile gateways in ad hoc networks

M Ahmed — 2007-10-02T09:22:27-00:00

Personal, Indoor and Mobile Radio Communications, 2002. The 13th IEEE International Symposium on, Vol. 4 (2002), pp. 1660-1664 vol.4.

The dynamic nature of a mobile ad hoc network (MANET) may result in a cluster of nodes being isolated from the rest of the network, especially when deployed in a terrain with blockages. To provide connectivity between the partitions of an ad hoc network that might occur due to mobility, a 'range extension' network can be employed. Such a network might consist of airborne communication platforms, or geostationary/low-Earth-orbit satellites maintaining communication links with specific 'gateway' nodes that are dispersed among the mobile ground nodes. Thus, to communicate with a node that is geographically distant or belongs to a different network partition, an ad hoc node can relay its data packets through an appropriate mobile gateway and via the range extension network. In such an architecture, MANET is divided into different domains with a mobile gateway deployed for each domain. The objective, then, is to determine the position and trajectory of the gateways to optimize network performance metrics such as throughput and latency. In this paper, computation of the optimal position for a gateway is shown to be equivalent to a linear optimization problem by means of some simplifying but realistic assumptions. An algorithm is proposed for the control of the gateway trajectory. The practical constraints imposed by the velocity and maneuverability of the gateways are taken into account. Simulation results show a 10-15% improvement in the throughput and latency, per gateway domain, if a gateway has a dynamic trajectory whose locus follows the computed optimal position, as compared to a gateway that is statically placed at a fixed position, or to a gateway that has a random trajectory.

Rerouting Time and Queueing in Proactive Ad Hoc Networks

Vinh Pham — 2007-06-01T22:37:50-00:00

Performance, Computing, and Communications Conference, 2007. IPCCC 2007. IEEE Internationa (2007), pp. 160-169.

In a MAINET network where nodes move frequently, the probability of connectivity loss between nodes might be high, and communication sessions may easily loose connectivity during transmission. The routing protocol is designed to find alternative paths in these situations. This rerouting takes time, and the latency is referred to as the rerouting time. This paper investigates the rerouting time of proactive routing protocols and shows that the rerouting time is considerably affected by queueing. Simulations and analysis are conducted to explore the problem. Finally, we propose a MAC-layer solution that reduces the rerouting time problems due to queueing. Simulations and analysis show that the solution is so effective that it eliminates the entire problem in many situations.

A novel cross-layer routing scheme of ad hoc networks with multi-rate mechanism

Guangsong Yang — 2006-11-10T15:10:14-00:00

Wireless Communications, Networking and Mobile Computing, 2005. Proceedings. 2005 International Conference on, Vol. 2 (2005), pp. 701-704.

A novel cross-layer routing technique was proposed for ad hoc networks with multi-rate mechanism based on node monitoring information. Combining SNR measure on physical layer and delay estimate on MAC layer, we propose a routing metric which selects the route with wide bandwidth, lower delay and less congestion. The routing technique is shown to improve performance of ad hoc network significantly.

Analysis and evaluation of the TCP/IP protocol stack of LINUX

Guo Chuanxiong — 2006-10-17T19:14:06-00:00

Communication Technology Proceedings, 2000. WCC - ICCT 2000. International Conference on, Vol. 1 (2000), pp. 444-453 vol.1.

With the rapid progress of high-speed network technology, the communication speed between hosts will reach Gbit/s. So it is important to investigate the traditional TCP/IP protocol stack to find out whether it is suitable for high-speed communication and can provide QoS or not. Based on this consideration, the LINUX TCP/IP stack's structure, the buffer management, the procedures for sending and receiving data, and the interaction with the OS are analyzed in this paper. A probing node method is proposed to investigate the internal structure of the stack. With this method, the throughput of the stack, the time consuming of each layer and the queuing of the IP layer at high speed are tested. Our experiments show that the throughput of the TCP/IP stack of LINUX can reach 360 Mbit/s at the sending side and 150 Mbit/s when the local host device is used for bi-directional operation, the protocol stack can he improved to support higher speed; the percentages of the various costs of the TCP/IP protocol suite have changed greatly, zero-copy and zero-scan techniques cannot improve the performance dramatically; there is no queuing at the receiving side of the IP layer, so FCFS (first come first served scheduler) is enough, but a more sophisticated packet scheduler such as WFQ (weighted fair queuing) is needed at the sending layer of the IP layer to provide QoS in the future

Improving performance of a real ad-hoc network by tuning OLSR parameters

C Gomez — 2006-10-05T09:49:11-00:00

Computers and Communications, 2005. ISCC 2005. Proceedings. 10th IEEE Symposium on (2005), pp. 16-21.

A key element for MANET performance is the routing protocol. Surprisingly, little effort has been devoted up to now to analyzing the impact of routing protocol parameter settings on MANET performance. We define and study in detail the route change latency (RCL) after link failures, a critical performance metric in a non-static ad-hoc scenario, and its dependence on routing protocol parameter settings and implementation issues using OLSR. We experiment with a set of OLSR settings in a real network environment and derive its potential effect in a generic situation, showing that end-to-end connectivity can be enhanced using different parameter settings from the default ones.

PARMA: A PHY/MAC Aware Routing Metric for Ad-Hoc Wireless Networks with Multi-Rate Radios

Suli Zhao — 2005-08-25T14:03:14-00:00

World of Wireless Mobile and Multimedia Networks, 2005. WoWMoM 2005. Sixth IEEE International Symposium on a (2005), pp. 286-292.

Ad-hoc wireless networks with multi-rate radios (such as 802.11a, b, g) require a new class of MAC/PHY aware metrics that take into account factors such as physical-layer link speed and MAC-layer channel congestion. Conventional "layer 3" ad-hoc routing algorithms typically make routing decisions based on the minimum hop-count (MH). Use of the MH metric leads to selection of paths with few hops but one or more of these hops may turn out to be low-speed radio links due to adaptive rate selection at the physical layer. In this paper, we investigate a new cross-layer routing metric that takes into account both physical layer link speed as well as estimated channel congestion, thus aiming to minimize end-to-end delay that includes both transmission and access times. The proposed "PARMA" routing metric will thus help spread the traffic across the "good links and nodes" in the network, increasing network capacity and reducing packet loss and delay. This paper presents the design and implementation of the proposed PARMA metric for proactive ad-hoc routing protocols such as DSDV. DSDV modifications for incorporating the MAC/PHY aware metric into an ns-2 simulation model are given. Simulation results for typical multi-rate 802.11 ad-hoc network scenarios show that the proposed cross-layer PHY/MAC aware metric achieves significantly higher network throughput and decreases network congestion by selecting paths with high bit-rate links while also avoiding areas of MAC congestion.

A cross-layer feature for an efficient forwarding strategy in wireless ad hoc networks

L Romdhani — 2006-06-14T17:21:09-00:00

Advanced Information Networking and Applications, 2006. AINA 2006. 20th International Conference on, Vol. 1 (2006), pp. 741-746.

In this work, we present a Cross-Layer Forwarding Strategy (CLFS), which is based on the cooperation between the new IEEE 802.11e MAC protocol (EDCA) and the On-Demand AODV routing protocol. The proposal aims to minimize the number of Forwarding nodes (FN) by hop, in the network. By this way, we decrease the contention amount and we improve the medium utilization. The selection of FN is based on maximum battery level and queue occupancy. These informations are injected into routing requests and replies crossing nodes in the network. Then, each node is able to select the FN that will participate in path establishment. In order to maintain a fair node capability, the forwarding procedure is dynamically distributed and assigned to nodes in the network. Moreover, an Adaptive Transmission Opportunity (ATXOP) mechanism, is derived from the EDCA. It aims to share the transmission channel fairly according to traffic load of nodes. We demonstrate that CLFS has good network performance, specially in term of throughput, that can be significantly improved. Moreover, it achieves a high degree of fairness among applications.

Opportunistic routing in multi-hop wireless networks

Sanjit Biswas — 2006-06-13T18:02:15-00:00

SIGCOMM Comput. Commun. Rev., Vol. 34, No. 1. (January 2004), pp. 69-74.

Ad Hoc Routing Using Directional Antennas

R Choudhury — 2006-06-13T18:00:57-00:00

(2002)

This report addresses the problem of using directional antennas in ad hoc routing. Although the problems with utilizing directional antennas have been visited in the past, the research has been confined mostly to issues related to medium access control. To determine whether directional antennas are beneficial to ad hoc networks, it is necessary to evaluate the impact of directional antennas on the performance of routing protocols as well. In this report, we evaluate the performance of a...

A cautionary perspective on cross-layer design

V Kawadia — 2006-06-13T17:48:48-00:00

Wireless Communications, IEEE [see also IEEE Personal Communications], Vol. 12, No. 1. (2005), pp. 3-11.

Recently, in an effort to improve the performance of wireless networks, there has been increased interest in protocols that rely on interactions between different layers. However, such cross-layer design can run at cross purposes with sound and longer-term architectural principles, and lead to various negative consequences. This motivates us to step back and reexamine holistically the issue of cross-layer design and its architectural ramifications. We contend that a good architectural design leads to proliferation and longevity, and illustrate this with some historical examples. Even though the wireless medium is fundamentally different from the wired one, and can offer undreamt of modalities of cooperation, we show that the conventional layered architecture is a reasonable way to operate wireless networks, and is in fact optimal up to an order. However the temptation and perhaps even the need to optimize by incorporating cross-layer adaptation cannot be ignored, so we examine the issues involved. We show that unintended cross-layer interactions can have undesirable consequences on overall system performance. We illustrate them by certain cross-layer schemes loosely based on recent proposals. We attempt to distill a few general principles for cross-layer design. Moreover, unbridled cross-layer design can lead to spaghetti design, which can stifle further innovation and be difficult to upkeep. At a critical time when wireless networks may be on the cusp of massive proliferation, the architectural considerations may be paramount. We argue that it behooves us to exercise caution while engaging in cross-layer design.

Improving the Performance of MANET Routing Protocols using Cross-Layer Feedback

Srinath Perur — 2006-05-15T10:02:10-00:00

We suggest a simple cross-layer feedback mechanism from the Medium Access Control (MAC) layer to the Address Resolution Protocol (ARP) module which can improve the performance of Mobile Ad hoc Network (MANET) routing protocols. It involves allowing the MAC layer of a mobile node to learn of the IP to MAC address mapping of nodes from broadcast packets that it receives. We show that allowing the MAC layer to create ARP table entries leads to dramatic improvements in route acquisition times using ...

ARP Considered Harmful: Manycast Transactions in Ad Hoc Networks

Casey Carter — 2006-04-26T16:31:36-00:00

(March 2003)

ARP handles neighbor discovery and address resolution in infrastructure networks, but is inadequate for Mobile Ad Hoc Networks (MANETs). Thus, many MANET routing protocols include a neighbor discovery mechanism. This separation of neighbor discovery and address resolution is a fundamental design problem that causes packet loss, particularly when the communication is manycast, a novel variant of multicast communication. Our approach, automatic address resolution, moves address resolution into...

Cross-layer design: a survey and the road ahead

V Srivastava — 2006-04-25T14:28:56-00:00

Communications Magazine, IEEE, Vol. 43, No. 12. (2005), pp. 112-119.

Of late, there has been an avalanche of cross-layer design proposals for wireless networks. A number of researchers have looked at specific aspects of network performance and, approaching cross-layer design via their interpretation of what it implies, have presented several cross-layer design proposals. These proposals involve different layers of the protocol stack, and address both cellular and ad hoc networks. There has also been work relating to the implementation of cross-layer interactions. It is high time that these various individual efforts be put into perspective and a more holistic view be taken. In this article, we take a step in that direction by presenting a survey of the literature in the area of cross-layer design, and by taking stock of the ongoing work. We suggest a definition for cross-layer design, discuss the basic types of cross-layer design with examples drawn from the literature, and categorize the initial proposals on how cross-layer interactions may be implemented. We then highlight some open challenges and new opportunities for cross-layer design. Designers presenting cross-layer design proposals can start addressing these as they move ahead.

Survey on Mobile Ad Hoc Network Routing Protocols and Cross-Layer Design

L Qin — 2006-04-19T23:49:07-00:00

(August 2004)

A "mobile ad hoc network" (MANET) is an autonomous system of mobile routers connected by wireless links. The routers are free to move randomly and organize themselves arbitrarily; thus, the network's wireless topology may change rapidly and unpredictably. Such a network may operate in a standalone fashion, or may be connected to the Internet. Multi hop, mobility, large network size combined with device heterogeneity, bandwidth and battery power constrain make the design of adequate routing protocols a major challenge. In recent years, many routing protocols have been proposed for MANET. Basically these protocols can be fit in one of two major categories: on-demand such as AODV [1] and DSR [2], and proactive such as DSDV [3] and OLSR [4]. The review and performance comparison of these protocols are in [5][6][7]. A more comprehensive survey can be found in [8]. In this survey, we will not focus on individual routing protocols; instead we will discuss some new ideas proposed recently mainly to improve MANET throughput and scalability in different ways with some new routing metrics, new technologies such as multi-rate, multi-channel and hierarchical structure, by using cross-layer design.

Does the IEEE 802.11 MAC protocol work well in multihop wireless ad hoc networks?

S Xu — 2005-05-26T11:44:38-00:00

Communications Magazine, IEEE, Vol. 39, No. 6. (2001), pp. 130-137.

The IEEE 802.11 MAC protocol is the standard for wireless LANs; it is widely used in testbeds and simulations for wireless multihop ad hoc networks. However, this protocol was not designed for multihop networks. Although it can support some ad hoc network architecture, it is not intended to support the wireless mobile ad hoc network, in which multihop connectivity is one of the most prominent features. In this article we focus on the following question: can the IEEE 802.11 MAC protocol function well in multihop networks? By presenting several serious problems encountered in an IEEE 802.11-based multihop network and revealing the in-depth cause of these problems, we conclude that the current version of this wireless LAN protocol does not function well in multihop ad hoc networks. We thus doubt whether the WaveLAN-based system is workable as a mobile ad hoc testbed