Recent NS2/NS3 Projects and Abstract

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A Power Control MAC Protocol for Ad Hoc Networks 

This paper presents a power control MAC protocol that al-lows nodes to vary transmit power level on a per-packet basis. Several researchers have proposed simple modi_cations of IEEE 802.11 to incorporate power control. The main idea of these power control schemes is to use di_erent power levels for RTS-CTS and DATA-ACK. Speci_cally, maximum transmit power is used for RTS-CTS, and the minimum required transmit power is used for DATA-ACK transmissions in order to save energy. However, we show that these schemes can degrade network throughput and can result in higher energy consumption than when using IEEE 802.11 without power control. We propose a power control protocol which does not degrade throughput and yields energy saving.

 Zone Based Multicast Routing Protocol for Mobile Ad-Hoc Network

A Mobile Ad-hoc network (MANET) is composed of mobile nodes without using infrastructure. There are several virtual architectures used in the protocol without need of maintaining state information for more robust and scalable membership management. In this paper, we propose a Robust and Scalable Geographic Multicast protocol (RSGM). Both the control messages and data packets are forwarded along efficient tree-like paths, but there is no need to explicitly create and actively maintain a tree structure. To avoid periodic flooding of the source information throughout the network, a well-organized source tracking mechanism is designed. We are analyzing the protocols RSGM, SPBM and ODMRP with the performance metrics such as packet delivery ratio, control overhead, average path length and average joining delay by varying moving speed, node density, group size and network ranges.

 
An Efficient Mechanism to Detect Wormhole Attacks in Wireless Ad-hoc Networks

 
Important applications of Wireless Ad Hoc Networks make them very attractive to attackers, therefore more research is required to guarantee the security for Wireless Ad Hoc Networks. In this paper, we proposed a transmission time based mechanism (TTM) to detect wormhole attacks – one of the most popular & serious attacks in Wireless Ad Hoc Networks. TTM detects wormhole attacks during route setup procedure by computing transmission time between every two successive nodes along the established path. Wormhole is identified base on the fact that transmission time between two fake neighbors created by wormhole is considerably higher than that between two real neighbors which are within radio range of each other. TTM has good performance, little overhead and no special hardware required. TTM is designed specifically for Ad Hoc On-Demand Vector Routing Protocol (AODV) but it can be extended to work with other routing protocols.

 

Pre-allocation of Unused Bandwidth Algorithm: A QoS Control Protocol for 802.16 Network

we propose a new allocation method in this paper.With it, the allocation work is partitioned into three rounds. In the first round, the slots are allocated sequentially based on the maximal sustained rate of each queue. In the second round, the left slots are allocated with the Weighted Round Robin. If there are slots left, the packets in all queues have been scheduled after this round. Then, the third round can be continued. For this round, a method for forecasting the arrival rate of the arriving packets in each queue is proposed. Then, the left slots are assigned according to the fore casted arrival rate of each queue. Comparing to the other protocols, those packets sent in this round can be delivered almost one frame earlier. This can decrease the average delay of the network and improve the performance for the WiMAX system.

Toward Fuzzy Traffic Adaptation Solution in Wireless Mesh Networks

​Wireless technologies are becoming an essential part of our daily life. These technologies are expected to provide a wide variety of real-time applications; hence, there is a vital need to provide quality-of-Service (QoS) support. One of the key mechanisms to supportQoSis traffic egulation. Thebasic idea behind traffic regulation is to measure the network state (e.g., load) in order to adapt the rate of carefully selected application flows. In this paper, we propose a novel model, called FuzzyWMN, which can be used to implement traffic adaptation in Wireless Mesh Networks (WMNs).The objective of FuzzyWMNis to compute the rate adaptation to apply to application flows according to the current network state; it relies on two parameters to meet this objective: (1) packet delays between sources and destinations; and (2) buffer ccupancy of network nodes. The proposed model combines the essential notions of both fuzzy logic theory and Petri nets; this enables FuzzyWMN to realize traffic adaptation in networks characterized by information uncertainty and imprecision due to the dynamic traffic behavior, channel interferences, etc. Extensive simulations show that FuzzyWMN achieves stable end-to-end delay and good throughput under different network conditions.

The Three-Tier Security Scheme in Wireless Sensor Networks with Mobile Sinks

​Mobile sinks (MSs) are vital in many wireless sensor network (WSN) applications for efficient data accumulation, localized sensor reprogramming, and for distinguishing and revoking compromised sensors. However, in sensor networks that make use of the existing key predistribution schemes for pairwise key establishment and authentication between sensor nodes and mobile sinks, the employment of mobile sinks for data collection elevates a new security challenge: in the basic probabilistic and q-composite key predistribution schemes, an attacker can easily obtain a large number of keys by capturing a small fraction of nodes, and hence, can gain control of the network by deploying a replicated mobile sink preloaded with some compromised keys. This article describes a three-tier general framework that permits the use of any pairwise key predistribution scheme as its basic component. The new framework requires two separate key pools, one for the mobile sink to access the network, and one for pairwise key establishment between the sensors. To further reduce the damages caused by stationary access node replication attacks, we have strengthened the authentication mechanism between the sensor and the stationary access node in the proposed framework. Through detailed analysis, we show that our security framework has a higher network resilience to a mobile sink replication attack as compared to the polynomial pool-based scheme.

A Study of Energy-Aware Traffic Grooming in Optical Networks: Static and Dynamic Cases

Less attention has been given to energy aware optical counterparts, compared to the research in energy-aware wireless and ethernet networks. In this paper, we consider energy aware traffic grooming problems in optical networks for both static and dynamic cases. Rather than simply considering a logical architecture of an optical node, we specifically look further into the modular physical architecture. We show that by reusing already active physical components during request allocations, we can significantly reduce the total number of active components and, hence, total energy consumption in the network, especially when traffic load is low. Since energy usage is an important element of operational expenditure, this approach provides the financial motivation for service providers along with the desired environmental motivation. We present a mathematical formulation of the problems, propose auxiliary graph based heuristics,and justify our cases compared to traditional approaches, based on simulation results. Index Terms—Energy-efficiency, modular switch architecture,
optical networks, traffic grooming.

​​State-Aware Pointer Forwarding Scheme With Fast Handover Support in a PMIPv6 Domain

​Abstract—Proxy mobile IPv6 (PMIPv6) has been developed as a network-based mobility management protocol by the Internet Engineering Task Force. Mobility for individual mobile nodes (MNs) is supported by network entities. PMIPv6 thus eliminates mobility signaling from the MNs as it does not require a mobility stack at the MNs. However, during handovers of MNs, PMIPv6 induces unnecessary location update traffic and suffers the packet loss, which downgrades the quality of mobility support.In this paper, we introduce a state-aware pointer forwarding scheme with fast handover support, called FC-PMIPv6, to further enhance the performance of mobility support in a PMIPv6
domain. In FC-PMIPv6, a pointer forwarding chain between mobility access gateways (MAGs) is established to reduce location update traffic to a local mobility anchor during handovers of an MN. The current mobility state of the MN is also considered in deciding whether the forwarding chain should be prolonged or refreshed by an MAG serving the MN. This mobility state consideration in pointer forwarding reduces unnecessary traffic for the location update and guarantees the efficiency of packet transmission. In addition, a fast handover process is adopted to reduce the handover latency and avoid the packet loss during handovers. We develop analytical models to study the performance of FC-PMIPv6, which consider both the signaling cost and the packet transmission cost. Numerical results not only demonstrate that FC-PMIPv6 outperforms the basic PMIPv6 protocol, but also present a relationship between an optimized length of a forwarding chain and a mobility state of an MN.From the conducted numerical results, for example, it is shown that the signaling cost of FC-PMIPv6 is enhanced up to 23% over the basic PMIPv6 protocol. In addition, simulation results on the weighted signaling cost are provided to demonstrate the  performance improvement of our FC-PMIPv6 compared with the basic PMIPv6 protocol. Index Terms—Fast handover, packet transmission cost, pointer forwarding, proxy mobile IPv6 (PMIPv6), signaling cost.

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A QoS-Oriented Distributed Routing Protocol for Hybrid Wireless Networks

​As wireless communication gains popularity, significant research has been devoted to supporting real-time transmission with stringent Quality of Service (QoS) requirements for wireless applications. At the same time, a wireless hybrid network that integrates a mobile wireless ad hoc network (MANET) and a wireless infrastructure network has been proven to be a better alternative for the next generation wireless networks. By directly adopting resource reservation-based QoS routing for MANETs, hybrids networks inherit invalid reservation and race condition problems in MANETs. How to guarantee the QoS in hybrid networks remains an open problem. In this paper, we propose a QoS-Oriented Distributed routing protocol (QOD) to enhance the QoS support capability of hybrid networks. Taking advantage of fewer transmission hops and anycast transmission features of the hybrid networks, QOD transforms the packet routing problem to a resource scheduling problem. QOD incorporates five algorithms: 1) a QoS-guaranteed neighbor selection algorithm to meet the transmission delay requirement, 2) a distributed packet scheduling algorithm to further reduce transmission delay, 3) a mobility-based segment resizing algorithm that adaptively adjusts segment size according to node mobility in order to reduce transmission time, 4) a traffic redundant elimination algorithm to increase the transmission throughput, and 5) a data redundancy elimination-based transmission algorithm to eliminate the redundant data to further improve the transmission QoS. Analytical and simulation results based on the random way-point model and the real human mobility model show that QOD can provide high QoS performance in terms of overhead, transmission delay, mobility-resilience, and scalability.
 

FLAP: An Efficient WLAN Initial Access Authentication Protocol

​Nowadays, with the rapid increase of WLAN-enabled mobile devices and the more widespread use of WLAN, it is increasingly important to have a more efficient initial link setup mechanism, and there is a demand for a faster access authentication method faster than the current IEEE 802.11i. In this paper, through experiments we observe that the authentication delay of 802.11i is intolerable under some scenarios, and we point that the main reason resulting in such inefficiency is due to its design from the framework perspective which introduces too many messages. To overcome this drawback, we propose an efficient initial access authentication protocol, FLAP, which realizes the authentications and key distribution through two roundtrip messages. We formally prove that our scheme is more secure than the four-way handshake protocol. Our practical measurement result indicates that FLAP can improve the efficiency of EAP-TLS by 94.7 percent. Extensive simulations are conducted in different scenarios, and the results demonstrate that when a WLAN gets crowded the advantage of FLAP becomes more salient. Furthermore, a simple and practical method is presented to make FLAP compatible with 802.11i. Index Terms—Authentication, WLAN, 802.11i

​COFFEE: A Context-Free Protocol for Stimulating Data Forwarding in Wireless Ad Hoc Networks

​Reputation based and credit-exchange based approaches have been studied extensively to enforce cooperation among non-cooperative nodes in wireless ad hoc networks. Most of the existing solutions are fundamentally context-based ones, which need to accurately identify selfish behaviors, securely maintain the context, and appropriately punish the selfish nodes. These requirements are extremely difficult to satisfy if not impossible. From a completely new angle, this paper proposes a context-free protocol, COFFEE, to enforce cooperation among
selfish nodes, which has the ability to transmit a packet over the path successfully without the dependency on the information of other packets’ transmission. Considering that every node in the network is rational, during the packet forwarding stage, if the intermediate nodes can not clearly tell whether the packet is destined to them or not, they can not simply drop the packet. Thus, in our proposed COFFEE protocol, through introducing several techniques, for any packet received by any node, the node thinks the packet could be destined to it and forwards the packet to find out the answer. Detailed analysis and performance evaluation have been conducted to demonstrate the effectiveness of the proposed protocol.

 Prioritized Optimal Channel Allocation Schemes for Multi-Channel Vehicular Networks

The IEEE 1609.4 standard has been proposed to provide multi-channel operations in wireless access for vehicular environments (WAVE), where all channels are periodically synchronized into control and service intervals. Communication device in each vehicle will stay at the control channel for negotiation and contention during the control interval, and thereafter switch to one of the service channels for data transmission in the service interval. In this paper, based on the concept of cognitive radio (CR), the vehicles are categorized into primary providers (PPs) that intend to transmit safety-related messages and secondary providers (SPs) with non-safety information to be delivered. The prioritized optimal channel allocation (POCA) approaches are proposed to improve channel utilization of IEEE 1609.4 standard for multi-channel vehicular networks. Prioritized channel access is analyzed in the POCA schemes in order to increase the transmission opportunity of PPs. Moreover, depending on whether the CR network is distributed or centralized, the optimal channel-hopping sequence and optimal channel allocation is assigned for SPs based on dynamic programming and linear programming technique, respectively. These schemes are designed to consider optimal load balance between both channel availability and channel utilization within the throughput constraints of PPs. With the adoption of proposed POCA schemes, simulation results show that maximum throughput of SPs can be achieved with guaranteed quality-of-service requirement for PPs.

SWIMMING: Seamless and Efficient WiFi-Based Internet Access from Moving Vehicles

Demand for Internet access from moving vehicles has been rapidly growing. Meanwhile, the overloading issue of cellular networks is escalating due to mobile data explosion. Thus, WiFi networks are considered as a promising technology to offload cellular networks. However, there pose many challenging problems in highly dynamic vehicular environments for WiFi networks. For example, connections can be easily disrupted by frequent handoffs between access points (APs). A scheme, called SWIMMING, is proposed to support seamless and efficient WiFi-based Internet access for moving vehicles. In uplink, SWIMMING operates in a “group unicast” manner. All APs are configured with the same MAC and IP addresses, so that packets sent from a client can be received by multiple APs within its transmission range. Unlike broadcast or monitor mode, group unicast exploits the diversity of multiple APs, while keeping all the advantages of unicast. To avoid possible collisions of ACKs from different APs, the conventional ACK decoding mechanism is enhanced with an ACK detection function. In downlink, a packet destined for a client is first pushed to a group of APs through multicast. This AP group is maintained dynamically to follow the moving client. The packet is then fetched by the client. With the above innovative design, SWIMMING achieves seamless roaming with reliable link, high throughput, and low packet loss. Testbed implementation and experiments are conducted to validate the effectiveness of the ACK detection function. Extensive simulations are carried out to evaluate the  performance of SWIMMING. Experimental results show that SWIMMING outperforms existing schemes remarkably.​

Multicast Rendezvous in Fast-Varying DSA Networks

Establishing communications between devices in a dynamic spectrum access (DSA) system requires the communicating parties to “rendezvous” before transmitting data packets. Frequency hopping (FH) is an effective rendezvous method that does not rely on a predetermined control channel. Previous FH-based rendezvous designs mainly target unicast rendezvous, and do not intrinsically support multicast rendezvous, where a group of nodes need to rendezvous simultaneously. Furthermore, these designs do not account for fast primary user (PU) dynamics, leading to long time-to-rendezvous (TTR). In this paper, we exploit the uniform  [k]  -arbiter and Chinese Remainder Theorem quorum systems to develop three FH-based multicast rendezvous algorithms, which provide different tradeoffs between rendezvous efficiency (e.g., low TTR) and security (e.g., robustness to node compromise). Our rendezvous algorithms are tailored for asynchronous and spectrum-heterogeneous DSA systems. To account for fast PU dynamics, we develop an algorithm for adapting the proposed FH designs on the fly. This adaptation is done through efficient mechanisms for channel ordering and quorum selection. Our simulations validate the effectiveness of the proposed rendezvous algorithms, their PU detection accuracy, and their robustness to insider attacks.