Performance assessment of multicast node placement for multicast routing in WDM networks with sparse light splitting

This article examines all-optical multicast routing for wavelength-routed optical networks with sparse Multicast Capable (MC) nodes in two phases. The first phase is MC node placement and use of a simple and straightforward Maximum Path Count First (MPCF) algorithm to obtain candidates for MC nodes. The second phase is multicast routing with MC-based schemes that minimizes the number of wavelength channels with minimum transmission delay as required by a given multicast session, in that a light-tree is first constructed to connect MC nodes in a multicast group by using two algorithms, namely, the Pre-computing Minimum Cost (PMC) tree algorithm and the Pre-computing Shortest Path (PSP) tree algorithm. System performance of the proposed MPCF MC node placement algorithm is compared with that of the Normalized Cuts (NC) MC node placement algorithm for both PMC and PSP multicast routing. Furthermore, simulation results compare PMC and PSP multicast routing based on MPCF and NC node placement with Re-route-to-Source (RTS), Re-route-to-Any (RTA), Member-First (MF), and Member-Only (MO) multicast routing based on a light forest for a given multicast session in terms of average number of wavelengths needed, average blocking probability, and mean maximum transmission delay.

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.

Performance analyses of serial-mode multicasting scheme in optical packet switched networks

The serial-mode multicasting scheme (SM), which can achieve duplication, buffering, and serial export of optical multicast packets in Optical Packet Switched (OPS) networks, is experimentally studied in this paper. Based on the experimental results, several limitations of this scheme, such as the multicast latency and signal impairment, are discussed. In addition, its performance in OPS networks is investigated by computer simulations. From the simulation results, a conclusion can be drawn that compared with the parallel-mode multicasting scheme (PM) producing multiple simultaneous copies of the optical packets by an optical power splitter or other devices, the SM scheme can increase the multicast success ratio and reduce the multicast retransmission times at the costs of some signal impairments and some extra transmission latency.

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.

Locally Optimal Source Routing for energy-efficient geographic routing

We analyze the problem of finding an energy-efficient path from a source node to a destination using geographic routing. Existing schemes have neglected the fact that neighbors which are not closer to the destination than the current node can still reduce energy consumption by taking part in the selected path. Moreover, recent works have confirmed that the generally used Unit Disk Graph to model Wireless Sensor Networks does not represent accurately the behavior of real links. We propose a new scheme called Locally Optimal Source Routing (LOSR) that is able to use neighbors which do not provide advance toward the destination to reduce the overall energy consumption while still avoiding routing loops. Using an Automatic Repeat reQuest (ARQ) mechanism hop by hop we overcome the problems caused by errors in radio transmissions and we introduce a novel routing metric, which accounts for those errors in the energy consumption. Our simulation results show that the proposed scheme outperforms existing solutions over a variety of scenarios and network densities.

Robust Multi-Path Zone Routing Protocol for Video Transport Over Reconfigurable Wireless Networks

Multimedia transport has stringent bandwidth, delay, and loss requirements. It is a great challenge to support such applications in reconfigurable wireless networks (RWNs). Using multiple paths in parallel for multimedia transport provides a new degree of freedom in designing robust multimedia transport systems. In this paper, we provide a multi-path extension to zone routing protocol (ZRP) to support video transmission over RWNs. We compare ZRP and our multi-path routing scheme by using NS-2 simulator. The experiments show that our method is effective in improving the robustness of video transport over RWNs.

A Reliable Multicast Routing Protocol Based on Recovery Points and FEC in Mobile Ad-hoc Networks

Multicasting is an essential service for mobile ad-hoc networks. A major challenge for multicasting in mobile ad-hoc networks (MANETs) is the unstable forwarding path. This work presents a reliable multicasting protocol for mobile ad-hoc networks. A virtual backbone is used as a shared structure for multiple sessions. A lost packet recovery scheme is developed for reliable packet transmission, called the Recovery Point (RP) scheme. The RP scheme maintains the data packets received from the source for recovering lost packets for its downstream RPs. In addition, we combine the Forward Error Correction (FEC) technology with our RP scheme to enhance the reliability of our RP scheme. A mergence scheme for RP is also proposed to avoid excessive control overhead. Our RP and FEC based scheme can be used to improve the reliability and efficiency of the traditional non-acknowledged multicasting approach. Experiments were conducted to evaluate the proposed multicasting scheme. The results demonstrate that our scheme outperforms other schemes in terms of packet delivery ratio and multicast efficiency. Furthermore, the simulation results also demonstrate that our approach is stable in networks with high mobility.

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.

Performance Enhancement of Fast Handover for MIPv6 by Reducing Out-of-Sequence Packets

FMIPv6 can reduce packet loss using a tunnel-based handover mechanism which relies on L2 triggers, such as transmitting a packet from a previous access router (PAR) to a new access router (NAR). However, this mechanism may result in decreasing the performance of TCP due to out-of-sequence packets arriving between the tunneled packets from the Home Agent and PAR, and the directly transmitted packets from the correspondent node (CN). In this paper, we propose a new scheme called EF-MIPv6 that uses a modified snoop protocol to prevent the packet reordering problem. This new scheme can prevent sequence reordering of data packets and improve the performance of TCP using enhanced fast binding update (EF-BU). This approach requires modification of the TCP header to execute the last packet expression from the PAR, include a new polling data packet, and use the modified access point system. Simulation results demonstrate that managing the packet sequence in our proposed scheme greatly increases the overall TCP performance in a Mobile IPv6 and FMIPv6 networks.

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.

Joint Design of Routing and Medium Access Control for Hybrid Mobile Ad Hoc Networks

Efficient routing and medium access control (MAC) are very important for Mobile Ad hoc Networks (MANETs). Most existing routing and MAC protocols consider homogeneous ad hoc networks, in which all nodes are modeled as the same, i.e., they have the same communication capabilities and characteristics. Although a homogeneous network model is simple and easy to analyze, it misses important characteristics of many realistic MANETs such as military battlefield ad hoc networks. In addition, a homogeneous ad hoc network suffers from poor performance and scalability. In many ad hoc networks, multiple types of nodes do co-exist; and some nodes have larger transmission power, higher transmission data rate, and better processing capability, are more reliable and robust than other nodes. Hence, a hybrid network model is more realistic and provides many advantages for designing better routing and MAC protocols. In this paper, we present a new routing protocol called Hybrid Routing, which is specifically designed for hybrid MANETs. In addition, a novel MAC protocol is jointly designed for hybrid MANETs. Extensive simulations demonstrate that the proposed routing MAC protocols have very good performance.

Scalable architectures for all-optical label swapping nodes

All-Optical Label Swapping (AOLS) nodes are believed to be part of the future networks. The original node designs, however, are very hard scalable. This article presents three alternatives that swap labels analogous to the original design. Two of the proposed new switches use the same all-optical technology to parallelly compare labels but, they divide fibres in data wavelengths that only transport payloads and label wavelengths that only transport labels. The third design sequentially compares the incoming label with addresses in the node available in order to make the routing decision. All three architectures are compared in terms of hardware necessary to perform routing.

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.

A framework for the multicast lifetime maximization problem in energy-constrained wireless ad-hoc networks

We consider the problem of maximizing the lifetime of a given multicast connection in wireless networks that use directional antennas and have limited energy resources. We provide a globally optimal solution to this problem for a special case of using omni-directional antennas. This graph theoretic approach provides us insights into more general case of using directional antennas, and inspires us to produce a group of heuristic algorithms. Experimental results show that our algorithms outperform other energy-aware multicast algorithms significantly in terms of multicast lifetime.

A dynamic hop count shifting RWA algorithm for wavelength routed optical networks

In this article, we find that the limiting hop count in a lightpath impacts on the performance of optical networks. Based on this observation, we propose a dynamic hop count shifting (DYHOS) algorithm that limits the hop count of lightpaths dynamically, depending on the traffic load. The proposed algorithm searches an available route, while minimizing the waste of network resources and limiting excessive traffic on the network. Hence, the proposed algorithm increases the network throughput and reduces the blocking probability. Comparing with shortest path routing and adaptive path routing algorithms, we show the performance of the proposed algorithm has the lowest blocking probability influenced by the hop count of lightpaths for a given routing algorithm.

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.

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.

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.

A New Routing Metric for Satisfying Both Energy and Delay Constraints in Wireless Sensor Networks

Besides energy constraint, wireless sensor networks should also be able to provide bounded communication delay when they are used to support real-time applications. In this paper, a new routing metric is proposed. It takes into account both energy and delay constraints. It can be used in AODV. By mathematical analysis and simulations, we have shown the efficiency of this new routing metric.

Information-based connection algorithm for supporting QoS in nested mobility network

A multihop mobile wireless network can be a collection of wireless mobile nodes forming a temporary network without the aid of any established infrastructure or centralized administration. Mobile nodes communicate with each other using multihop wireless links. Each mobile node in the network also acts as a router, which forwards data packets to other nodes. A main challenge in the design of this mobile network is the development of dynamic routing protocols that can efficiently find routes between two communicating nodes that often change the network topology drastically and unpredictably. All communications between the nodes inside the mobile network and the global Internet must be maintained, although the mobile router (MR) connecting the other mobile network to the global Internet must change their address; and mobile nodes suffer from end-to-end delay and handoff delay. That is to say, hereafter the packets sailing for the mobile node would not be routed directly for the destination, but will always make a detour by way of HA to the target node. In this paper, we suggest Information-based Connection Algorithm that adds keyword management method in order to resolve such a problem, simulations are carried out with NS-2 for performance evaluation. The results of the simulations show an improvement on throughput and handoff delay, and consequently the QoS improvement.