Stimulating Node Cooperation in Mobile Ad hoc Networks

Mobile Ad hoc Networks (MANETs) rely on the cooperation of nodes for packet routing and forwarding. Much of the existing work in MANETs assume that mobile nodes (possibly owned by selfish users) will follow prescribed protocols without deviation. However, a user may misbehave due to several advantages resulting from noncooperation, the most obvious being power saving. As such, the network availability is severely endangered. Hence, enforcing the cooperation among nodes becomes a very important issue. Several different approaches have been developed to detect non-cooperative nodes or deal with the non-cooperative behavior of mobile nodes in MANETs. These protocols are first surveyed in details in this paper. It is found that the proposed approaches have several concerns that prevent them from really enforcing the node cooperation in MANETs. Thus, a new scheme that can stimulate and also enforce nodes to cooperate in a selfish ad hoc environment is presented. We also present a mechanism to detect and exclude potential threats of selfish mobile nodes. The simulation results indicate that by using the proposed scheme, MANETs can be robust against nodes’ misbehaving and the performance of the network is enhanced many folds when compared to other existing schemes.

Cluster-Based Autoconfiguration for Mobile Ad hoc Networks

IP address autoconfiguration of mobile nodes is highly desirable in the practical usage of most mobile ad hoc networks (MANETs). This paper proposes cluster-based autoconfiguration, a novel approach for the efficient address autoconfiguration of MANETs. The cluster structure derived from clustering techniques is used to manage address assignment and conflict resolution. By introducing the concept of virtual address agents (AAs), the proposed approach can be applicable to many existing clustering protocols. Finally, analysis and simulation demonstrate that the proposed scheme outperforms the previous autoconfiguration approaches.

A Cross-layer Approach to Channel Assignment in Wireless Ad Hoc Networks

To improve the capacity of wireless ad hoc networks by exploiting multiple available channels, we propose a distributed channel assignment protocol that is based on a cross-layer approach. By combining channel assignment with routing protocols, the proposed channel assignment protocol is shown to require fewer channels and exhibit lower communication, computation, and storage complexity than existing channel assignment schemes. A multi-channel MAC (MC-MAC) protocol that works with the proposed channel assignment protocol is also presented. We prove the correctness of the proposed channel assignment protocol. In addition, through a performance study, we show that the proposed protocol can substantially increase throughput and reduce delay in wireless ad hoc networks, compared to the IEEE 802.11 MAC protocol and an existing multi-channel scheme.

DTN Based Dominating Set Routing for MANET in Heterogeneous Wireless Networking

In mobile communications, effective inter-networking is mandatory in order to support user roaming among various types of wireless networks while maintaining connectivity. In this paper, we propose a super node system architecture to achieve the connectivity over interconnected heterogeneous wireless access networks, which employs the delay-tolerant network (DTN) concept to overcome the problem of potential intermittent connections caused by user roaming and ensures message delivery in the presence of a long disconnection period. By introducing the concept of virtual network topology, we present a new routing technique for mobile ad hoc networks (MANETs) within the system architecture, which redefines the dominating-set based routing for the challenged network environment. A time based methodology is presented to predict the probability of future contacts between node pairs for constructing the virtual network topology. Simulation results demonstrate the effectiveness of the proposed dominating-set based routing scheme under the DTN system architecture.

Minimum delay routing for wireless networks with STDMA

STDMA emerges as a promising channel access technique for providing Quality of Service (QoS) guarantees in multi-hop ad hoc networks such as community mesh and sensor networks. The contention-free channel access combined with spatial reuse of the channel provide significant benefits in the energy/throughput trade-off. On the other hand, the time-multiplexed communication introduces extra delay on the packets when relayed by intermediate nodes. Hence in large wireless sensor networks or mesh networks, where data is routed over several hops before reaching the data sink, STDMA protocols may introduce high end-to-end latency due to the reservation-based access policy. We argue that a suitable routing protocol specifically designed for reservation-based Medium Access Control (MAC) protocols can alleviate their high-latency drawback. Following this argument, we propose first such routing algorithms working on top of a generic STDMA MAC protocol. First, we consider routing with data fusion and present our GreenWave routing idea. We show that our algorithm significantly reduces the end-to-end delay when compared to routing over the shortest-hop paths. Second, we consider routing without data fusion, by taking into account the effect of congestion along the paths on the end-to-end delays. We provide a QIP formulation of the problem, and present a lower bound and a heuristic algorithm to bound the optimal solution. Based on the centralized heuristic algorithm, we propose a distributed, dynamic routing protocol GreenWave routing with Congestion and Flow control (GWCF), which uses a novel congestion and flow control technique utilizing the underlying contention-free protocol. We show by simulations that GWCF routing significantly improves the end-to-end delay while increasing the network throughput when compared to routing over shortest paths.

GMZRP: Geography-aided Multicast Zone Routing Protocol in Mobile Ad Hoc Networks

This paper presents the design and evaluation of a highly efficient on-demand multicast routing protocol for mobile ad hoc networks (MANETs). The protocol, called Geography-aided Multicast Zone Routing Protocol (GMZRP), eliminates as much as possible duplicate route queries by using a simple yet effective strategy for propagating the multicast route request (MRREQ) packets. GMZRP is the first hybrid multicast protocol taking the advantages of both topological routing and geographical routing. It partitions the network coverage area into small zones and guarantees that each geographic zone is queried only once. GMZRP maintains a multicast forwarding tree at two levels of granularities, i.e., the zone granularity and the node granularity. By doing this, it can easily handle route breakage since the zone level information can help recover the link failure at the node level. The results of the performance evaluation of GMZRP using simulation show that, comparing with the well-known multicast protocol ODMRP (On-Demand Multicast Routing Protocol), GMZRP has much lower protocol overhead in terms of query packets and, meanwhile, achieves competing packet delivery ratio and shorter delivery latency.

Density-Independent,Scalable Search in Ad Hoc Networks

We analyze the asymptotic cost of discovering a route within a flat ad hoc network and we show that one can discover a route with cost that is proportional only to the area of the network, which is independent of the number of network nodes. Furthermore, we show that this is optimal and that bordercasting (a query propagation protocol where a node retransmits a query to a set of nodes at some hop-distance away) possesses this density-independence property. We present the design of bordercast and the associated maintenance protocols, and we evaluate their performance. In particular, we highlight that the aggregation of local information by bordercasting at each network node is a fundamental building block for the construction of scalable protocols in flat ad hoc networks.

SDMAC: Selectively Directional MAC protocol for wireless mobile ad hoc networks

Using directional antennas in wireless mobile ad hoc networks can greatly improve the transmission range as well as the spatial reuse. However, it will also cause some problems such as deafness problem and hidden terminal problem, which greatly impair the network performance. This paper first proposes a MAC protocol called Selectively Directional MAC (SDMAC) that can effectively address these problems and significantly improve the network throughput. Then two improvements on SDMAC are proposed. The first one is to improve the network throughput by scheduling the packets in the queue (a scheme called Q-SDMAC), thus the head-of-line (HOL) blocking problem can be addressed. The second one is to relax the assumption that each node knows the relative directions of its neighboring nodes and use caches to buffer those relative directions (a scheme named Q-SDMAC using cache). Extensive simulations show that: (1) SDMAC can achieve much better performance than the existing MAC protocols using directional antennas; (2) The network throughput can be significantly improved by scheduling the packets in the queue; (3) Using caches can still achieve high network throughput when nodes are moving; and (4) Network throughput decreases when directional antennas have side lobe gain.

An Energy Conservation MAC Protocol in Wireless Sensor Networks

Wireless sensor networks use battery-operated computing and sensing devices. Because of the limitation of battery power in the sensor nodes, energy conservation is a crucial issue in wireless sensor networks. Consequently, there is much literature presenting energy-efficient MAC protocols based on active/sleep duty cycle mechanisms to conserve energy. Convergecast is a common communication pattern across many sensor network applications featuring data gathering from many different source nodes to a single sink node. This leads to high data collision rates, high energy consumption, and low throughput near the sink node. This paper proposes an efficient slot reservation MAC protocol to reduce energy consumption and to make transmission more efficient in data gathering wireless sensor networks. The simulation results show that our protocol provides high throughput, low delivery latency and low energy consumption compared to other methods.

AdHoc Probe: end-to-end capacity probing in wireless ad hoc networks

Knowledge of end-to-end path capacity is useful for video/audio stream adaptation, network management and overlay design. Capacity estimation in wired and last-hop wireless networks has been extensively investigated, but a thorough and systematic study in ad hoc, multihop wireless networks is still lacking. Yet the rate of a wireless link can change dynamically (and rapidly) due to changes in interference, distance or energy optimization policy. Timely knowledge of path capacity is key to efficient routing, traffic management and application deployment. In this paper, we present AdHoc Probe, a packet-pair based technique, to estimate end-to-end path capacity in ad hoc wireless networks. We apply AdHoc Probe to path capacity estimation in auto rate wireless networks with variable displacement and interference; and, in remote wireless networks across the Internet. Using analysis, simulation and testbed experiments, we show AdHoc Probe can withstand mobility and is able to trace the rate adaptation of wireless networks timely and correctly. AdHoc Probe is simpler, faster and much less intrusive than current schemes.

A Location Aware Mobility based Routing Protocol for the Bluetooth Scatternet

Bluetooth is a most promising technology designed for the wireless personal area networks for the cable replacement. In this paper, a location aware mobility based routing scheme for the Bluetooth scatternet is proposed that constructs the links dynamically. Our proposed routing protocol requires location information of the nodes and constructs the route between any source and destination and reduces the number of hops. Besides, the network routing problems are analyzed and role switch operations are proposed to mitigate the problems. Moreover, the roles switch and route optimization operations are also proposed to improve route performance. Rigorous simulation works are done to evaluate the performance of our protocol in terms of mobility speed and number of mobile nodes and to compare our results with similar Bluetooth routing protocols. It is observed that our protocol outperforms in terms of energy consumption and transmission packet overheads as compared to similar Bluetooth routing protocols.

A route maintaining algorithm using neighbor table for mobile sinks

In the wireless microsensor networks, both source and sink nodes can be changed or mobile. The movement of source and sink may lead to the breakage of existing routes. In most routing protocols, query packets are broadcasted to correct a broken route between source and sink, which causes significant communication overhead in terms of both energy and delay. In order to support the sink mobility of conventional routing protocols, we propose a simple route maintaining algorithm which does not use the flooding method. Since the proposed algorithm does not require the information on the geometric location of sensor nodes, it can be easily adopted in most existing routing protocols including Ad Hoc On Demand Distance Vector (AODV) and Direct Diffusion (DD). Experimental results show that the proposed algorithm drastically improves the conventional routing protocols in terms of both energy and delay in case of mobile sinks.

Symbiotic Networks: Towards a New Level of Cooperation Between Wireless Networks

In the future, many wireless networks, serving diverse applications, will co-exist in the same environment. Today, wireless networks are mostly optimized in a rather opportunistic and/or selfish way: optimizations methods only use a local view of the network and environment, as they try to achieve the best performance within its own network. The optimizations are very often limited to a single layer and cooperation between networks is only happening through the use of gateways. In this paper, we suggest an alternative paradigm for supporting cooperation between otherwise independent networks, called ‘symbiotic networking’. This new paradigm can take many forms, such as sharing of network resources, sharing of nodes for communal routing purposes and sharing of (networking) services. Instead of optimizing network parameters within the individual networks, symbiotic networking solutions operate across network boundaries. Parameters are optimized between the networks and communal protocols are developed, leading to a more global optimization of the scarce network resources. In this paper, we describe several scenarios which can profit from symbiotic networking and illustrate a strategy for supporting networking protocols which can operate across network boundaries. Ultimately, through the disappearance of network boundaries and the introduction of cross-layer/cross-node/cross-network cooperation, symbiotic networks takes the notion of cooperation to a new level, paving the way for a true network symbiosis.

Routing scalability in multi-domain DWDM networks

This paper studies routing scalability in multi-domain DWDM networks. Although inter-domain provisioning has been well studied for packet/cell-switching networks, the wavelength dimension (along with wavelength conversion) poses many challenges in multi-domain DWDM settings. To address these concerns a detailed GMPLS-based hierarchical routing framework is proposed for multi-domain DWDM networks with wavelength conversion. This solution uses mesh topology abstraction schemes to hide domain-internal state. However related inter-domain routing loads can be significant here, growing by the square of the number of border nodes. To address these scalability limitations, improved inter-domain routing update strategies are also proposed and the associated performance of inter-domain lightpath RWA and signaling schemes studied.

Cross-layer Routing Design in Cognitive Radio Networks by Colored Multigraph Model

In this paper, the cross-layer design routing in cognitive radio(CR) networks is studied. We propose a colored multigraph based model for the temporarily available spectrum bands, called spectrum holes in this paper. Based on this colored multigraph model, a polynomial time algorithm with complexity O(n ²) is also proposed to develop a routing and interface assignment, where n is the number of nodes in a CR network. Our algorithm optimizes the hop number of routing, meanwhile, the adjacent hop interference (AHI) is also optimized locally.

ASR: anonymous and secure reporting of traffic forwarding activity in mobile ad hoc networks

Nodes forward data on behalf of each other in mobile ad hoc networks. In a civilian application, nodes are assumed to be selfish and rational, i.e., they pursue their own self-interest. Hence, the ability to accurately measure traffic forwarding is critical to ensure proper network operation. These measurements are also often used to credit nodes based on their level of participation, or to detect loss. Past solutions employ neighbor monitoring and reporting on traffic forwarding of nodes. These methods are not applicable in civilian networks in which neighbor nodes lack the desire or ability to perform the monitoring function. Such environments occur frequently in which neighbor hosts are resource constrained, or in networks where directional antennas are used and reliable eavesdropping is difficult or impossible. In this article, we propose a protocol that uses nodes on the data path to securely produce packet-forwarding reports. Reporting nodes are chosen randomly and secretly so that malicious nodes cannot modify their behavior based upon the monitoring point. The integrity and authenticity of reports are preserved through the use of secure link layer acknowledgments and monitoring reports. The robustness of the reporting mechanism is strengthened by forwarding the report to multiple destinations (source and destination). We explore the security, cost, and accuracy of our protocol.

Proactive mitigation of impact of wormholes and sinkholes on routing security in energy-efficient wireless sensor networks

Sensor networks are deployed in a variety of environments for unattended operation. In a hostile terrain, sensor nodes are vulnerable to node capture and cryptographic material compromise. Compromised nodes can be used for launching wormhole and sinkhole attacks in order to prevent sensitive data from reaching intended destinations. Our objective in this paper is mitigating the impact of undetected compromised nodes on routing. To this end, we develop metrics for quantifying risk of paths in a network. We then introduce a novel routing approach: Secure-Path Routing (SPR) that uses expected path risk as a parameter in routing. Quantified path risk values are used in routing to reduce traffic flow over nodes that have high expected vulnerability. Selecting low risk routes may lead to the choice of energy-expensive routes. Thus, we develop algorithms for balancing risk with other path selection parameters, including energy consumption. We conduct simulation experiments to evaluate the effectiveness of our approach and study the tradeoff between security and energy. Simulation shows that SPR can be quite effective at increasing traffic flow over legitimate routes and that the impact of SPR on network lifetime is negligible.

Energy-Aware Georouting with Guaranteed Delivery in Wireless Sensor Networks with Obstacles

We propose, end-to-end (EtE), a novel EtE localized routing protocol for wireless sensor networks that is energy-efficient and guarantees delivery. To forward a packet, a node s in graph G computes the cost of the energy weighted shortest path (SP) between s and each of its neighbors in the forward direction towards the destination which minimizes the ratio of the cost of the SP to the progress (reduction in distance towards the destination). It then sends the message to the first node on the SP from s to x: say node x′. Node x′ restarts the same greedy routing process until the destination is reached or an obstacle is encountered and the routing fails. To recover from the latter scenario, local minima trap, our algorithm invokes an energy-aware Face routing that guarantees delivery. Our work is the first to optimize energy consumption of Face routing. It works as follows. First, it builds a connected dominating set from graph G, second it computes its Gabriel graph to obtain the planar graph G′. Face routing is invoked and applied to G′ only to determine which edges to follow in the recovery process. On each edge, greedy routing is applied. This two-phase (greedy–Face) EtE routing process reiterates until the final destination is reached. Simulation results show that EtE outperforms several existing geographical routing on energy consumption metric and delivery rate. Moreover, we prove that the computed path length and the total energy of the path are constant factors of the optimal for dense networks.

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Ad hoc networks beyond unit disk graphs

In this paper, we study an algorithmic model for wireless ad hoc and sensor networks that aims to be sufficiently close to reality as to represent practical realworld networks while at the same time being concise enough to promote strong theoretical results. The quasi unit disk graph model contains all edges shorter than a parameter d between 0 and 1 and no edges longer than 1. We show that—in comparison to the cost known for unit disk graphs—the complexity results of geographic routing in this model contain the additional factor 1/d ². We prove that in quasi unit disk graphs flooding is an asymptotically message-optimal routing technique, we provide a geographic routing algorithm being most efficient in dense networks, and we show that classic geographic routing is possible with the same asymptotic performance guarantees as for unit disk graphs if .

Simulation Study of the SIR in Mobile Ad-Hoc Networks

Most studies for mobile ad hoc network (MANET) assume fixed communication range/sensing range (CR/SR) without consideration of signal-to-interference ratio (SIR). In this Letter, we study the impact of SIR with different CR/SR settings by computer simulation. A model with the worst-case scenario, where we allow as many pair of sender/receiver nodes as possible in the simulated area, is developed in this study. Results show that transmission rules based on fixed CR/SR only may not be adequate for use in MANET due to low SIR.