H. Anthony Chan

Review: Bandwidth aggregation in heterogeneous wireless networks: A survey of current approaches and issues

Future wireless networks are envisaged to consist of a variety of integrated and jointly managed radio access technologies (RATs). This is motivated by the complementary features of the individual RATs. When in the overlapping coverage of the integrated RATs, a multimode terminal can use them simultaneously, thus aggregating bandwidth to enhance performance of high-bandwidth applications. However, there are challenges that must be addressed to achieve efficient bandwidth aggregation. Packet reordering is the most dominant challenge. Packet reordering can lead to excessive delays that can affect real-time applications; it can also affect throughput of TCP applications adversely. To circumvent the reordering problem and other challenges associated with simultaneous use of the terminals multiple interfaces, bandwidth aggregation solutions are developed. This paper reviews existing bandwidth aggregation solutions in heterogeneous wireless networks. Challenges and several open research issues in the design of bandwidth aggregation approaches are also outlined. To the best of our knowledge, this is the first comprehensive review of existing bandwidth aggregation techniques in heterogeneous wireless networks. This paper, therefore, provides important lessons and information from current bandwidth aggregation solutions, which can be used to guide the development of more efficient bandwidth aggregation approaches.

Joint call admission control algorithms: Requirements, approaches, and design considerations

It is envisioned that next generation wireless network (NGWN) will be heterogeneous where different radio access technologies coexist. This vision of NGWN has led to the development of new call admission control (CAC) algorithms specifically designed for heterogeneous wireless networks. This paper reviews recent call admission control algorithms for heterogeneous wireless networks. Benefits and requirements of joint CAC (JCAC) algorithms are discussed. We examine eight different approaches for selecting the most appropriate radio access technology (RAT) for incoming calls in NGWN and classify the JCAC algorithms based on these approaches. The advantages and disadvantages of each approach are discussed. We analyze six different design considerations for JCAC algorithms. These design considerations are centralization, optimization, number of network selection criteria, call type, centricity, and prediction. A more thorough understanding of JCAC in heterogeneous wireless networks and its research trends may help one to design better JCAC algorithms.

Adaptive bandwidth management and joint call Admission control to enhance system utilization and QoS in heterogeneous wireless networks

The coexistence of different cellular networks in the same area necessitates joint radio resource management for enhanced QoS provisioning and efficient radio resource utilization. We propose adaptive bandwidth management and joint call admission control (JCAC) scheme for heterogeneous cellular networks. The objectives of the proposed adaptive JCAC scheme are to enhance average system utilization, guarantee QoS requirements of all accepted calls, and reduce new call blocking probability and handoff call dropping probability in heterogeneous wireless networks. We develop a Markov chain model for the adaptive JCAC scheme and derive new call blocking probability, handoff call dropping probability, and average system utilization. Performance of the proposed adaptive JCAC scheme is compared with that of nonadaptive JCAC scheme in the same heterogeneous wireless network. Results show an improvement in average system utilization of up to 20%. Results also show that connection-level QoS can be significantly improved by using the proposed adaptive JCAC scheme.

Proxy mobile IP with distributed mobility anchors

Existing wireless networks typically support mobility by routing via a mobility anchor in a home network, but such via routing can result in non-optimized routes. This paper proposes a method to distribute the functions of the mobility anchor to different networks to avoid such non-optimized routes. It proposes a distributed mobility anchors architecture consisting of home mobility anchors (H-MA) at the home networks and visited mobility anchors (V-MA) at the visited networks. It splits the functions of a mobility anchor into the logical functions of: (1) home network prefixes allocation, (2) location management (LM), and (3) mobility routing (MR). The V-MA performs MR function to avoid triangle routing problem in Proxy mobile IP, whereas the H-MA also performs the LM function. The needed location information of a mobile node (MN) is acquired by a V-MA from the H-MA only when a packet is first sent to the MN via the V-MA and are then cached at the V-MA to enable optimized MR for packets subsequently sent to the MN.

Joint Call Admission Control Algorithm for Fair Radio Resource Allocation in Heterogeneous Wireless Networks Supporting Heterogeneous Mobile Terminals

There is a problem of unfairness in allocation of radio resources among heterogeneous mobile terminals in heterogeneous wireless networks. Low-capability mobile terminals (such as single-mode terminals) sutTer high call blocking probability whereas high-capability mobile terminals (such as quad-mode terminals) experience very low call blocking probability, in the same heterogeneous wireless network. This paper proposes a joint call admission control (JCAC) algorithm to reduce this problem of unfairness. The proposed JCAC algorithm makes call admission decisions based on mobile terminal modality (capability), network load, and radio access technology (RAT) terminal support index. The objectives of the proposed JCAC algorithm are to reduce call blocking/ dropping probability, and ensure fairness in allocation of radio resources among heterogeneous mobile terminals in heterogeneous networks. We develop an analytical model to evaluate the performance of the proposed JCAC scheme in heterogeneous wireless networks and derive expression for call blocking/ dropping probability. The performance of the proposed JCAC algorithm is compared with that of other JCAC algorithm. Results show the proposed algorithm reduces call blocking/ dropping probability in the networks, and ensure fairness in allocation of radio resources among heterogeneous terminals.

PMIPv6 and MIH-enhanced PMIPv6 for mobility management in heterogeneous wireless networks

Next generation wireless networks will interwork hence combine resources of the available heterogeneous networks for connection support. Mobility across these networks will be inevitable. Thus, to support seamless connection migration between the networks, seamless handover is a necessary requirement. One of the requirements for ensuring seamless handover is the reduction of the delay that occurs during a handover procedure. Various mobility management protocols have been proposed and standardized to support mobility across heterogeneous networks but they cannot provide seamless handover in their current form. However, Proxy Mobile IPv6, which is a networked-based mobility management, goes a long way towards reducing handover delay. Enhancing it with a handover optimization mechanism, such as IEEE 802.21 MIH services, improves the handover performance even further. This paper therefore evaluates the performance of PMIPv6 versus PMIPv6 enhanced with MIH services. The results show that indeed PMIPv6 performs even better when enhanced with MIH in terms of reducing handover delay and reducing packet losses during handover across heterogeneous wireless networks.

Syntax, and semantics-based signature database for hybrid intrusion detection systems

Signature-based intrusion detection systems (IDSs) have the advantages of producing a lower false alarm rate and using less system resources compared to anomaly based systems. However, they are susceptible to obfuscation used by attackers to introduce new variants of the attacks stored in the database. Some of the disadvantages of signature-based IDSs can be attributed to the fact that they are mostly purely syntactic and ignore the semantics of the monitored systems. In this paper, we present the design and implementation of a signature database that assists a Specification-based IDS in a converged environment. Our design is novel in terms of considering the semantics of the monitored protocols alongside their syntax. Our protocol semantics awareness is based on the state transition analysis technique which models intrusions at a high level using state transition diagrams. The signature database is hierarchically designed to insure a balance between ease of use and fast retrieval in real time. The database prototype is tested against some implemented attacks and shows promising efficiency. Copyright

Optimal virtual network function placement in multi-cloud service function chaining architecture

Service Function Chaining (SFC) is the problem of deploying various network service instances over geographically distributed data centers and providing inter-connectivity among them. The goal is to enable the network traffic to flow smoothly through the underlying network, resulting in an optimal quality of experience to the end-users. Proper chaining of network functions leads to optimal utilization of distributed resources. This has been a de-facto model in the telecom industry with network functions deployed over underlying hardware. Though this model has served the telecom industry well so far, it has been adapted mostly to suit the static behavior of network services and service demands due to the deployment of the services directly over physical resources. This results in network ossification with larger delays to the end-users, especially with the data-centric model in which the computational resources are moving closer to end users. A novel networking paradigm, Network Function Virtualization (NFV), meets the user demands dynamically and reduces operational expenses (OpEx) and capital expenditures (CapEx), by implementing network functions in the software layer known as virtual network functions (VNFs). VNFs are then interconnected to form a complete end-to-end service, also known as service function chains (SFCs). In this work, we study the problem of deploying service function chains over network function virtualized architecture. Specifically, we study virtual network function placement problem for the optimal SFC formation across geographically distributed clouds. We set up the problem of minimizing inter-cloud traffic and response time in a multi-cloud scenario as an ILP optimization problem, along with important constraints such as total deployment costs and service level agreements (SLAs). We consider link delays and computational delays in our model. The link queues are modeled as M/D/1 (single server/Poisson arrival/deterministic service times) and server queues as M/M/1 (single server/Poisson arrival/exponential service times) based on the statistical analysis. In addition, we present a novel affinity-based approach (ABA) to solve the problem for larger networks. We provide a performance comparison between the proposed heuristic and simple greedy approach (SGA) used in the state-of-the-art systems. Greedy approach has already been widely studied in the literature for the VM placement problem. Especially we compare our proposed heuristic with a greedy approach using first-fit decreasing (FFD) method. By observing the results, we conclude that the affinity-based approach for placing the service functions in the network produces better results compared against the simple greedy (FFD) approach in terms of both, total delays and total resource cost. We observe that with a little compromise (gap of less than 10% of the optimal) in the solution quality (total delays and cost), affinity-based heuristic can solve the larger problem more quickly than ILP.

Enhancing PMIPv6 for better handover performance among heterogeneous wireless networks in a micromobility domain

This paper analyzes the reduction of handover delay in a network-based localized mobility management framework assisted by IEEE 802.21 MIH services. It compares the handover signaling procedures with host-based localized MIPv6 (HMIPv6), with network-based localized MIPv6 (PMIPv6), and with PMIPv6 assisted by IEEE 802.21 to show how much handover delay reduction can be achieved. Furthermore, the paper proposes and gives an in-depth analysis of PMIPv6 optimized with a handover coordinator (HC), which is a network-based entity, to further improve handover performance in terms of handover delay and packet loss while maintaining minimal signaling overhead in the air interface among converged heterogeneous wireless networks. Simulation and analytical results show that indeed handover delay and packet loss are reduced.

Detection of Zero-Day Polymorphic Worms Using Principal Component Analysis

Polymorphic worms pose a big challenge to the Internet security. The difficulty of detection of such a polymorphic worm is that it has more than one instance and very large efforts are needed to capture all these instances and to generate signatures. This paper proposes automatic system for signature generation for zero-day polymorphic worms. We have designed a novel double-honeynet system, which is able to detect new worms that have not been seen before. We apply Principal Component Analysis (PCA) to determine the most significant substrings that are shared between polymorphic worm instances and to use them as signatures. The system is able to generate signatures to match most polymorphic worm instances with low false positives and low false negatives.