OpenUCT :: Browsing by Author "Chan, H Anthony"

Browsing by Author "Chan, H Anthony"

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Open Access
Applying human-like intelligence to future generation network to improve communication efficiency
(2007) Li, Yang; Chan, H Anthony
In recent decades, communications network has evolved at drastic speed to provide advanced and intelligent services. This strengthening service provision owes to the successful establishment of various intelligent networks and the use of artificial intelligence, pervasive computing, and social networking in communications. It has consequently endowed network users with abundant choices of communication services. While these communications services are bringing convenience to human lives, people in turn are performing more tasks. The current network with its large number of available communications services is then often burdening network users with the complexity and inflexibility in using these services. In particular, the network lacks the initiative and the ability to investigate a user’s most recent communication needs and subsequently adjust the manner of service provision according to these needs and user connecting possibilities. The network needs to be more intelligent to handle these problems. We therefore propose importing human-like intelligence into the network to facilitate communication-session processing according to user needs.
Open Access
An assembly and offset assignment scheme for self-similar traffic in optical burst switching
(2006) Muwonge, Benon Kagezi; Chan, H Anthony
Optical Burst Switching (OBS) is a viable technology for the next generation core network. We propose an FEC-assembly scheme that efficiently assembles self-similar traffic and a Pareto-offset assignment rather than a constant offset assignment. Two buffers, a packet buffer and a burst buffer, are implemented at the Label Edge Router (LER), buffering traffic in the electronic domain. The assembler, between the packet and burst buffers, is served by the packet queue while the assembler serves the burst queue. We outline advantages of why burst assembly cannot be implemented independent of offset assignment. The two schemes must be implemented in a complementary way if QoS is to be realized in an OBS network. We show that there is a direct relation between OBS network performance with burst assembly and offset assignment. We present simulation results of the assembly and offset assignment proposals using the ns2 network simulator. Our results show that the combination of the proposed FEC-Based assembly scheme with the proposed Pareto-offset assignment scheme give better network performance in terms of burst drop, resource contention and delay. Key to any traffic shaping is the nature traffic being shaped. This work also compares performance of both traditional exponential traffic with realistic Self-Similar traffic of Internet traffic on the proposed assembly and offset assignment schemes. In our simulations, we assume that all Label Switch Routers (LSR) have wavelength converters and are without optical buffers. We use Latest Available Unused Channel with Void Filling (LAUC-VF) scheduling scheme and use Just Enough Time (JET) reservation scheme.
Open Access
Automated signature generation for Zero-day polymorphic worms using a Double-honeynet
(2012) Mohammed, Mohssen M Z E; Chan, H Anthony
This thesis proposes an accurate system for signature generation for Zero-day polymorphic worms. Thesis consists of two parts: In part one, polymorphic worm instances are collected by designing a novel Double-honeynet system, which is able to detect new worms that have not been seen before. Unlimited honeynet outbound connections are introduced to collect all polymorphic worm instances. Therefore this system produces accurate worm signatures. In part two, signatures are generated for the polymorphic worms that are collected by the Double-honeynet system. Both a Modified Knuth-Morris-Pratt (MKMP) Algorithm, which is string matching based, and a Modified Principal Component Analysis (MPCA), which is statistics based, are used.
Restricted
Benefits and requirements of interworking between wirelessLAN and 3G wireless
(2004) Chan, H Anthony
The IEEE 802.11 family of WirelessLAN enable broadband wireless access at low cost but has limited distance range. The 3G Wireless network enable wireless data access over much longer distance of cellular sites and with the handover and roaming can be used globally. Yet the 3G Wireless may be more expensive. The WirelessLAN and 3G Wireless have different capabilities in distance range, data rate, and in other features, and may complement each other. Combining WLAN and 3G Wireless data through interworking will enable these LAN and WAN technologies to complement each other to enhance the available wireless network services. These benefits are of value to both users and service providers. The requirements of interworking and the technological implications of these requirements are discussed here.
Open Access
Clustering algorithms for sensor networks and mobile ad hoc networks to improve energy efficiency
(2007) Wei, Dali; Chan, H Anthony
Many clustering algorithms have been proposed to improve energy efficiency of ad hoc networks as this is one primary challenge in ad hoc networks. The design of these clustering algorithms in sensor networks is different from that in mobile ad hoc networks in accordance with their specific characteristics and application purposes. A typical sensor network, which consists of stationary sensor nodes, usually has a data sink because of the limitation on processing capability of sensor nodes. The data traffic of the entire network is directional towards the sink. This directional traffic burdens the nodes/clusters differently according to their distance to the sink. Most clustering algorithms assign a similar number of nodes to each cluster to balance the burden of the clusters without considering the directional data traffic. They thus fail to maximize network lifetime. This dissertation proposes two clustering algorithms. These consider the directional data traffic in order to improve energy efficiency of homogeneous sensor networks with identical sensor nodes and uniform node distribution. One algorithm is for sensor networks with low to medium node density. The other is for sensor networks with high node density. Both algorithms organize the clusters in such a way that the cluster load is proportional to the cluster energy stored, thereby equalizing cluster lifetimes and preventing premature node/cluster death. Furthermore, in a homogeneous sensor network with low to medium node density, the clusterhead is maintained in the central area of the cluster through re-clustering without ripple effect to save more energy. The simulation results show that the proposed algorithms improve both the lifetime of the networks and performance of data being delivered to the sink. A typical mobile ad hoc network, which usually consists of moveable nodes, does not have a data sink. Existing energy-efficient clustering algorithms maintain clusters by periodically broadcasting control messages. In a typical mobile ad hoc network, a greater speed of node usually needs more frequent broadcasting. To efficiently maintain the clusters, the frequency of this periodic broadcasting needs to meet the requirement of the potentially maximum speed of node. When the node speed is low, the unnecessary broadcasting may waste significant energy. Furthermore, some clustering algorithms limit the maximum cluster size to moderate the difference in cluster sizes. Unfortunately, the cluster sizes in these algorithms still experience significant difference. The larger clusters will have higher burdens. Some clustering algorithms restrict the cluster sizes between the maximum and minimum limits. The energy required to maintain these clusters within the maximum and minimum sizes is quite extensive, especially when the nodes are moving quickly. Thus, energy efficiency is not optimized.
Open Access
Concurrent multipath transmission to improve performance for multi-homed devices in heterogeneous networks
(2016) Ramaboli, Allen Lehopotseng; Falowo, Olabisi E; Chan, H Anthony
Recent network technology developments have led to the emergence of a variety of access network technologies - such as IEEE 802.11, wireless local area network (WLAN), IEEE 802.16, Worldwide Interoperability for Microwave Access (WIMAX) and Long Term Evolution (LTE) - which can be integrated to offer ubiquitous access in a heterogeneous network environment. User devices also come equipped with multiple network interfaces to connect to the different network technologies, making it possible to establish multiple network paths between end hosts. However, the current connectivity settings confine the user devices to using a single network path at a time, leading to low utilization of the resources in a heterogeneous network and poor performance for demanding applications, such as high definition video streaming. The simultaneous use of multiple network interfaces, also called bandwidth aggregation, can increase application throughput and reduce the packets' end-to-end delays. However, multiple independent paths often have heterogeneous characteristics in terms of offered bandwidth, latency and loss rate, making it challenging to achieve efficient bandwidth aggregation. For instance, striping the flow's packets over multiple network paths with different latencies can cause packet reordering, which can significantly degrade performance of the current transport protocols. This thesis proposes three new solutions to mitigate the effects of network path heterogeneity on the performance of various concurrent multipath transmission settings. First, a network layer solution is proposed to stripe packets of delay-sensitive and high-bandwidth applications for concurrent transmission across multiple network paths. The solution leverages the paths' latency heterogeneity to reduce packet reordering, leading to minimal reordering delay, which improves performance of delay-sensitive applications. Second, multipath video streaming is developed for H.264 scalable video, where the reference video packets are adaptively assigned to low loss network paths to reduce drifting errors, thus combatting H.264 video distortion effectively. Finally, a new segment scheduling framework - which carefully considers path heterogeneity - is incorporated into the IETF Multipath TCP to improve throughput performance. The proposed solutions have been validated using a series of simulation experiments. The results reveal that the proposed solutions can enable efficient bandwidth aggregation for concurrent multipath transmission over heterogeneous network paths.
Open Access
A cross-layer mobility management framework for next-generation wireless roaming
(2007) Abdelatif, Mohamed Abdalla; Chan, H Anthony
This thesis proposes a mobility management framework that aims to provide a framework for advanced mobility algorithms that allows the challenges of next-generation roaming to be met. The framework features tools that gather context and content information, guarantee low-level QoS, provide security, and offer link and handoff management. The framework aims to be scalable and reliable for all-IP heterogeneous wireless networks whilst conforming to 4G service requirements.
Open Access
Distributed IP mobility management for hosts and networks
(2014) Ernest, Petro Pesha; Chan, H Anthony; Falowo, Olabisi E
The Internet was originally designed for stationary nodes. With the advancement of mobile nodes (such as smartphones and tablets) that have wireless Internet access capability, the original design of the Internet is no longer sufficient. These mobile nodes are capable of communicating while moving and changing their point of attachment in the Internet. To maintain communication session(s) continuity for these mobile nodes, the Internet needs mobility management mechanisms. The main mobility management protocols standardised by the Internet Engineering Task Force (IETF) are mobile IP (MIPv6 and MIPv4) and their numerous extensions and variants, including proxy MIP (PMIPv6 and PMIPv4). The architectural structures of these protocols employ a centralized mobility anchor to manage the mobility of the mobile nodes in the control and data planes. The mobility anchor manages the mobility binding information and the forwarding of data packets for all mobile nodes registered in the network. However, in the context of the rapid growth in the number of mobile users and the data traffic volume, as well as the trend towards a flat architecture in mobile networks, the centralized mobility management approach provides insufficient mobility support to the mobile nodes. For example, to manage the demand for increased mobile users, a huge amount of data traffic will be pushed to the centralized mobility anchor. Yet, routing huge volumes of traffic via the centralized mobility anchor can be non-optimal in terms of routing efficiency. Thus, the centralised mobility anchor can be a potential bottleneck, and a single point of failure. Consequently, failure of the mobility anchor may lead to a service outage for a large number of mobile nodes. Ultimately, the centralized mobility management approach does not scale well with the increase in number of mobile users and the data traffic volume. These problems are also costly to resolve within the centralized mobility management approach and its related centralized network architecture. Distributed mobility management (DMM) is one recent approach that can efficiently address the shortcomings of centralized mobility management. It provides an alternative paradigm for developing IP mobility management â€“ without employing centralized mobility anchors. In this paradigm, either the mobility anchors, or their mobility management functions, are distributed to different networks/elements. The mobility anchors, or the mobility management functions, are brought to the edge of the networks, which is closer to the mobile nodes. Distributed mobility management also offers dynamic mobility features that allow a mobile node to anchor traffic at different mobility anchors. However, to date, mobility management schemes that have been developed based on the DMM approach are still in the preliminary stages, and there is no current standard in place. These developed DMM schemes are still experiencing problems, such as long routing paths, especially for long-lasting data traffic, a lack of route optimization for ongoing communication, and a lack of synchronization of the mobile nodesâ€Ÿ location in different networks. Moreover, the majority of these proposed schemes still need to be analysed, in order to quantify their feasibility. The thesis proposes three novel network-based distributed mobility management schemes, which are based on the DMM approach. The schemes enhance PMIPv6 to work in a distributed manner, in order to address the problems of centralized mobility management. Furthermore, the schemes address the following issues: (1) the lack of route optimization for ongoing communication; (2) the lack of synchronization of the mobile nodesâ€Ÿ location in different networks; and (3) the long end-to-end packet delivery delay problems in recently proposed DMM schemes. The first scheme, called the network-based distributed mobility management scheme with routing management function at the gateways (DM-RMG), decomposes the logical mobility management functions of the Local Mobility Anchor (LMA) in PMIPv6 into internetwork location management (LM), routing management (RM), and home network prefix allocation (HNP) functions. After the decomposition, the RM function is collocated at the gateways of different networks. In this way, the data-plane routing function of the respective mobile nodes is served by the corresponding local RM function at the network gateway. The DM-RMG scheme offers distributed mobility management for individual mobile nodes (i.e., mobile hosts) during mobility events. DM-RMG also implements a mechanism to optimize the handover delay. The results obtained from analytical modelling and simulation show that the DM-RMG scheme outperforms the centralized mobility management schemes, as well as currently proposed distributed mobility management schemes in terms of the end-to-end packet delivery delay under different network load conditions. The optimized handover performance of the DM-RMG scheme, investigated under different traffic patterns and mobile node speeds, shows that the scheme also mitigates the internetwork handover delay and packet loss. The second proposed scheme, called network-based distributed mobility management for the network mobility (NDM-RMG), uses a similar approach to DM-RMG. However, it proposes a network-based DMM scheme for Network Mobility (NEMO). The main goal of the NDMRMG scheme is to address the problems of centralized mobility management protocols for NEMO, including the pinball routing problem in nested NEMO. NDM-RMG is compared with centralized mobility management schemes for NEMO, and recently proposed distributed IP mobility management schemes for NEMO by means of analytical modelling and simulation evaluations. NDM-RMG shows better performance in terms of reducing the packet delivery latency, the size of the packet header, and the packet overhead experienced over the wireless link. The third proposed scheme, called network-based distributed mobility management scheme with RM and HNP allocation functions distributed to the access routers (DM-RMA), distributes the RM and the HNP allocation functions at the access routers with the mobility client function. This brings the mobility-related functions closer to the mobile nodes, that is, to the edge of the network. An analytical model is developed to investigate the mobility cost performance of the scheme, due to signalling, packet delivery, and tunnelling. The analytical results indicate that DM-RMA performs better than the previous DMM schemes in terms of packet delivery, tunnelling and total costs. Network simulator-2 (ns-2) is used to model the DM-RMA scheme. The simulated scenarios confirm that DM-RMA performs better than other proposed DMM schemes in terms of reducing the location update latency at the location managers, end-to-end packet delivery delay, handover delay, and packet loss. In addition to the three proposed DMM schemes, this thesis proposes a routing optimization scheme for PMIPv6. The main goal of this scheme is to enable PMIPv6 to offer route optimization to mobile nodes in a PMIPv6 domain. The scheme reduces the route optimization-establishment latency, the packet delivery latency, and the packet loss. Using ns-2 simulations and considering different simulated scenarios, the results show that the scheme reduces route optimization-establishment latency and delayed packets during the route optimization operation, as compared to previously proposed PMIPv6 route optimization schemes. The results also show that the scheme reduces packet loss when a mobile node undergoes handover in the PMIPv6 domain.
Open Access
Efficient joint call admission control and bandwidth management schemes for QoS provisioning in heterogeneous wireless networks
(2008) Falowo, Olabisi Emmanuel; Chan, H Anthony
Next generation wireless network (NGWN) will be heterogeneous where different radio access technologies (RATs) coexist. This coexistence of different RATs necessitates joint radio resource management (JRRM) for enhanced QoS provisioning and efficient radio resource utilization. Joint call admission control (JCAC) algorithm is one of the joint radio resource management algorithms. The basic functions of a JCAC algorithm are to decide whether or not an incoming call can be accepted into a heterogeneous wireless network, and to determine which of the available RATs is most suitable to admit the incoming call. The objective of a JCAC algorithm is to guarantee the QoS requirements of all accepted calls and at the same time make the best use of the available radio resources. Traditional call admission control algorithms designed for homogeneous wireless networks do not provide a single solution to address the heterogeneous architecture, which characterizes NGWN. Consequently, there is need to develop JCAC algorithms for heterogeneous wireless networks. The thesis proposes three JCAC schemes for improving QoS and radio resource utilization, which are of primary concerns, in heterogeneous wireless networks. The first scheme combines adaptive bandwidth management and joint call admission control. The objectives of the first 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. The scheme consists of three components namely: joint call admission controller, bandwidth reservation unit, and bandwidth adaptation unit. Using Markov decision process, an analytical model is developed to evaluate the performance of the proposed scheme considering three performance metrics, which are new call blocking probability, handoff call dropping probability, and system utilization. Numerical results show that the proposed scheme improves system utilization and reduces both new call blocking probability and handoff call dropping probability. The second proposed JCAC scheme minimizes call blocking probability by determining the optimal call allocation policy among the available RATs. The scheme measures the arrival rates of different classes of calls into the heterogeneous wireless network. Using linear programming technique, the JCAC scheme determines the call allocation policy that minimizes call-blocking probability in the heterogeneous network. Numerical results show that the proposed scheme reduces call-blocking probability in the heterogeneous wireless network.
Open Access
An emission and discard priority scheme for optical burst switched networks
(2007) Acquaah, Pascal E K; Chan, H Anthony
Optical burst switching (OBS) is a promising technology designed to meet the growing demands for internet handwidth and better Quality of Service (QoS). This technology provides all optical and high speed switching to overcome the bottleneck of electronic routers in the core network. In this thesis, I describe several critical issues that affect OBS networks. I highlight the need to resolve contention efficiently and cost-effectively to improve QoS in OBS networks.
Open Access
Enhancing PMIPv6 for Better Handover Performance among Heterogeneous Wireless Networks in a Micromobility Domain
(Springer, 2010) Magagula, Linoh A; Falowo, Olabisi E; Chan, H Anthony
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.
Open Access
Evaluating collaborative filtering content recommenders for mobile phones
(2007) Piyasena, Indika Weliwe Gamage; Chan, H Anthony
The high adoption of mobile phones coupled with 3G technology can extend Internet access to new communities. Yet such access is currently impractical because mobile phone interfaces are cumbersome to use. In addition, hierarchical menus and search engines pose an interaction barrier to the unfamiliar. A content recommender is proposed to address these issues. Collaborative filtering is a technique developed to make predictions on unobserved items based on the preferences of similar users. User-based collaborative filtering has been identified as a simple, yet reasonably accurate scheme. An evaluation is conducted into how quickly this algorithm can identify preferred content based on user-content interactions.
Open Access
Host mobility management with identifier-locator split protocols in hierarchical and flat networks
(2012) Mulam, Muhana Magboul Ali; Chan, H Anthony; Ventura, Neco
As the Internet increasingly becomes more mobile focused and overloaded with mobile hosts, mobile users are bound to roam freely and attach to a variety of networks. These different networks converge over an IP-based core to enable ubiquitous network access, anytime and anywhere, to support the provision of services, that is, any service, to mobile users. Therefore, in this thesis, the researcher proposed network-based mobility solutions at different layers to securely support seamless handovers between heterogeneous networks in hierarchical and flat network architectures.
Open Access
A hybrid and cross-protocol architecture with semantics and syntax awareness to improve intrusion detection efficiency in Voice over IP environments
(2008) Barry, Bazara I A; Chan, H Anthony
Voice and data have been traditionally carried on different types of networks based on different technologies, namely, circuit switching and packet switching respectively. Convergence in networks enables carrying voice, video, and other data on the same packet-switched infrastructure, and provides various services related to these kinds of data in a unified way. Voice over Internet Protocol (VoIP) stands out as the standard that benefits from convergence by carrying voice calls over the packet-switched infrastructure of the Internet. Although sharing the same physical infrastructure with data networks makes convergence attractive in terms of cost and management, it also makes VoIP environments inherit all the security weaknesses of Internet Protocol (IP). In addition, VoIP networks come with their own set of security concerns. Voice traffic on converged networks is packet-switched and vulnerable to interception with the same techniques used to sniff other traffic on a Local Area Network (LAN) or Wide Area Network (WAN). Denial of Service attacks (DoS) are among the most critical threats to VoIP due to the disruption of service and loss of revenue they cause. VoIP systems are supposed to provide the same level of security provided by traditional Public Switched Telephone Networks (PSTNs), although more functionality and intelligence are distributed to the endpoints, and more protocols are involved to provide better service. A new design taking into consideration all the above factors with better techniques in Intrusion Detection are therefore needed. This thesis describes the design and implementation of a host-based Intrusion Detection System (IDS) that targets VoIP environments. Our intrusion detection system combines two types of modules for better detection capabilities, namely, a specification-based and a signaturebased module. Our specification-based module takes the specifications of VoIP applications and protocols as the detection baseline. Any deviation from the protocol’s proper behavior described by its specifications is considered anomaly. The Communicating Extended Finite State Machines model (CEFSMs) is used to trace the behavior of the protocols involved in VoIP, and to help exchange detection results among protocols in a stateful and cross-protocol manner. The signature-based module is built in part upon State Transition Analysis Techniques which are used to model and detect computer penetrations. Both detection modules allow for protocol-syntax and protocol-semantics awareness. Our intrusion detection uses the aforementioned techniques to cover the threats propagated via low-level protocols such as IP, ICMP, UDP, and TCP.
Open Access
Inter-subnet localized mobility support for host identity protocol
(Springer, 2011) Muslam, Muhana; Chan, H Anthony; Ventura, Neco
Host identity protocol (HIP) has security support to enable secured mobility and multihoming, both of which are essential for future Internet applications. Compared to end host mobility and multihoming with HIP, existing HIP-based micro-mobility solutions have optimized handover performance by reducing location update delay. However, all these mobility solutions are client-based mobility solutions. We observe that another fundamental issue with end host mobility and multihoming extension for HIP and HIP-based micro-mobility solutions is that handover delay can be excessive unless the support for network-based micro-mobility is strengthened. In this study, we co-locate a new functional entity, subnet-rendezvous server, at the access routers to provide mobility to HIP host. We present the architectural elements of the framework and show through discussion and simulation results that our proposed scheme has achieved negligible handover latency and little packet loss.
Open Access
Interactive gaming application servicefor the UCT IMS network
(2008) Mushabe, Allan; Chan, H Anthony
Interactive gaming is a major feature of social sectors. Until recently, interactive games have generally been restricted to solitary access networks. In other words, games have to be played on similar systems. The IP Multimedia Subsystem is designed to help with the convergence of different access networks by creating an all IP based network. In so doing, making it possible to have an interactive gaming application that conforms to all forms of access networks. As a result, the only significant requirements would be on the resources available by the access networks or the user terminals performance. This dissertation examines the concept of a gaming application which is accessible by all kinds of users.
Open Access
A low-cost design of multiservice SDH networks with multiple constraints
(2006) Karem, Tope Razaq; Chan, H Anthony
This study investigates the problem of ring-node assignment a Multiservice SDH/SONET Optical network design with constraints in capacity and differential delay. The problem is characterized as a graph-partitioning problem, and a heuristic algorithm based on constraints programming satisfaction technology is proposed.
Open Access
MAC and physical layer energy efficiency for ad hoc wireless sensor networks
(2006) Basich, Zoran Luka Josip; Chan, H Anthony
The research work undertaken involves the design of a new, energy efficient Medium Access Control (MAC) layer for Ad Hoc Wireless Sensor Networks (AHWSN). MAC solutions are either contention based or non-contention based. Energy inefficiencies in contention based MAC protocols suffered from collisions, overhearing, control overhead and idle listening. Non-contention based MAC protocols introduced TDMA I CDMA I FDMA that did not suffer from those problematic issues. However, they suffered from other problems, such as energy inefficient hierarchies. The hierarchy uses cluster-heads to co-ordinate neighbours which is a continual requires that is energy inefficient. The proposal named Colour TDMA MAC is introduced, which does not have a hierarchy or cluster-head problems. It uses a single channel and simple transmitters. It also uses a distributed algorithm from colouring graph mathematics to ensure that the hidden terminal and exposed terminal problems of wireless data communication do not occur. Colour TDMA MAC also introduces the two concepts that allow nodes to sleep longer. The two are: * The Timed PicoRadio * The Mailbox. A node may sleep when it is not using the channel. Yet it may use one of the above concepts to receive a message destined for it. In the case of the timed PicoRadio, the node is awakened if it is sleeping. In the case of the mailbox, the radio signal is stored in memory and when the microprocessor awakens, it can deal with the message. A comparison of the central idea (Colour TDMA MAC) to a mainstream contention based MAC protocol (S-MAC) for AHWSN reveals that S-MAC suffers from collisions and idle listening (to a great extent) which is energy wasted. Its other energy inefficiencies are overhearing and control overhead. The two scheduling algorithms are compared via timing diagrams to see which delivers a message successfully in the shortest time. They are also placed head to head in some random tests to evaluate which is more energy efficient. Research work shows that the Colour TDMA MAC greatly improves energy savings. On the downside, it trades off energy for channel usage, thus messages take longer to reach their destination. Results also show that the Colour TDMA MAC is exceptionally good for unicast messaging where both the sender and the destination are known.
Open Access
Multi-layer traffic engineering framework for inter-working multi-hop wireless networks
(2011) Salami, Oladayo M; Chan, H Anthony
The interworking of multi-hop wireless networks can conveniently provide ubiquitous seamless service and continual access for network users. Ubiquity can be achieved through multi-technology mobile terminals (nodes), which enables network users to access any available network. In addition, such nodes extend network coverage by relaying traffic for each other. However, to exploit the benefits of the internetworking, it is desirable to have appropriate traffic engineering (TE) mechanisms. Taking into account the co-existence of different physical and Medium Access Control (MAC) layer standards in the individual networks, the multi-hop communication capability and the impairment-prone wireless medium, TE becomes challenging.
Open Access
Multi-stage queuing with iterative probabilistic scheduling of IP traffic for QoS provisioning
(2006) Salami, Oladayo M; Chan, H Anthony; Dlodlo, Mqhele E
Queuing and scheduling are packet processing functions which provide quality of service (QoS) at the first level of the QoS architecture where routers reside. With the continued increase in network speed, queuing and scheduling of traffic needs to be performed at higher speed. In addition, processing co-existing IP traffic from different applications requiring QoS may complicate these functions. Virtual Output Queuing (VOQ) is a strategy that can queue traffic at line rate and achieve 100% throughput with an effective scheduling algorith. It maintains a separate queue for each output port at each inputport. With N input ports and N output ports in the router ther are N² such virtual output queues at the input. The challenge is to schedule the packets at the head on these N² queues.