Faculty of Engineering and Built Environment
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Item Services and applications security in IoT enabled networks(IEEE, 2018-12) Khumalo, Zephaniah Philani; Nleya, Bakhe; Gomba, Ndadzibaya Masimba; Mutsvangwa, Andrew5G wireless together with optical backbone networks are expected to be the main pillars of the envisaged next /future generation networking (N/FGN) infrastructures. This is an impetus to practical realization of an IoT network that will support and ensure relatively higher bandwidth as well as enhanced quality of service (QoS) in both access and core network sections. The high-speed wireless links at the network peripherals will serve as a conducive platform for device-to-device (D2D) communication. D2D driven applications and services can only be effective as well as secure assuming the associated machine type communication devices (MTCDs) have been successfully verified and authenticated. Typically, D2D type services and applications involve the interaction of several MTCDs in a group. As such, secure and effective D2D group-based authentication and key agreement (AKA) protocols are necessary. They need to inherently achieve efficacy in maintaining the group key unlink-ability as well as generate minimal signalling overheads that otherwise may lead to network congestion. In this paper we detail a secure and efficient Group AKA (Gr-AKA) protocol for D2D communication. Its performance is compared to that of existing similar protocols and is found to comparably lower both computational as well as signalling overhead requirements. Overall the analysis shows that the Gr-AKA protocol improves performance in terms of fulfilling D2D communication's security requirements.Item Energy-aware lightpath routing algorithm for optical transport networks(TELKOM, 2019-09-01) Gomba, Ndadzibaya Masimba; Nleya, Bakhe; Dewa, Mendon; Mutsvangwa, Andrew; Khumalo, Zephaniah PhilaniCurrent as well as future applications and services are characterized by bandwidth intensiveness and as such are directly driving the need for the deployment as well as operation of backbone networks that optimize on bandwidth provisioning. Since infrastructural hardware equipment requirements are trebling every two years because of continued surging bandwidth demands, the telecommunication industry is also a growing direct contributor to worldwide greenhouse gases (GHG) emissions as well as energy consumption. This is driving necessities to research on more energy efficient networking approaches. A novel optimized energy-aware lightpath routing (OEA-LR) algorithm is herein proposed. It primarily takes into account the effects of physical layer impairments (PLI) since their effects in high capacity translucent optical networks may not be ignored when formulating routing and wavelength assignment (RWA) algorithms. We assume an all-optical network hence connection requests from source to destination are entirely provisioned in the optical domain, thus optical-electrical-optical (OEO) conversions are not utilised. Both analytical and simulation results indicate that the proposed algorithm improves both energy efficiency operation as well as resource utilization of the network. We further conclude on a general observation of reciprocations between energy savings and blocking performance.Item Evaluation of wavelength congestion in transparent optical transport networks(IEEE, 2020-08) Gomba, Ndadzibaya Masimba; Nleya, Bakhe; Mutsvangwa, Andrew; Chidzonga, Richard F.Transparent Optical networks are generally regarded as a possible solution for the provisioning of ultrahigh speed transmission and switching capabilities to accommodate bandwidth hungry applications and services. Most of such applications and services involve streaming of high-definition video. However, since al source and destination pair establishments within a given Transparent optical transport network are assumed to be within optical signal reach, such networks do not incorporate regenerators. The lack of regenerators often leads to a serious degradation of the signal to noise ratio as a result of the effects of physical layer impairments accumulated as it traverses the network. This motivates us to propose and present a Q-factor tool that takes into account the various physical layer impairments. The proposed tool’s efficacy is evaluated by way of simulation.Item Evaluation of end-to-end latency for segmented bursts in OBS networks(IEEE, 2016) Mutsvangwa, Andrew; Nleya, Bahke; Gomba, Ndadzibaya Masimba; Ngeama, NdungaIn Optical Burst Switched (OBS) networks several contention resolution schemes such as wavelength conversion, fibre delay lines (FDLs), deflection routing and burst segmentation have been proposed. To provide the differential quality of service (QoS) for different classes of packets, priority-based segmented burst assembling at the edge nodes coupled with segment level transmission in the core nodes (in the event of congestion or contention) is proposed. All packets are assembled in units called segments according to two priorities, high priority (HP) and low priority (LP). HP segments are always placed at the head end of the composite burst as they are more delay sensitive, whereas the LP segments fill up at the tail end. Only in the event or anticipation of contention/ congestion occurrence, the affected section(s) of the network switch to segment transmission mode in which the composite burst is from this point decomposed into its individual segments and streamed (segment level transmission) along the same route to the destination end. The limited buffering in the core nodes will facilitate temporary buffering of the contending segments as since they are relatively smaller. The queuing at the inputs may lead to differential delays in the core nodes due to possible addition of segments from other links. This ultimately affects the inter-segment-gap between successive data segments ferrying packets of the same source thus leading to increased jittery whose magnitude may compromise the desirable QoS. In this paper we analyze inter-segment delay variations as a function of the number of nodes traversed.Item Contention and congestion minimization in OBS networks(2017) Gomba, Ndadzibaya Masimba; Nleya, BakheAll-optical networks (AON) based optical burst switching (OBS) promise to be the ultimate backbone network technology solution for next generation( NG) as well as fu ture generation (FG)networks because of their relatively higher resources utilization, great flexibility at lower cost and potential massive bandwidth capacities both at trans mission and switching levels. By design, buffering is not provisioned in interior nodes. End users exchange data with one another through end-to-end light channels, called lightpaths in which wavelength continuity is maintained. In practice, their establish ing, in a cost effective manner remains an inescapable challenge. The routing and wave length assignment (RWA) problem entices successful establishment of a physical route for each lightpath connection request, assigning a wavelength to each route and at the same time ensm·ing end to end continuity, subject to the limited number of wave lengths. The wavelengths must be assigned such that no lightpaths can share the same wavelength simultaneously on a given fibre, or else contentions may occur. Some data bursts may be discarded whenever contention occurs among multiple bursts that arrive simultaneously at any interior node using the same wavelength and are intended for the same output port. Because of the buffer-less nature of OBS networks, conten tion/congestion in the core network can quickly lead to degradation in overall network performance at moderate to high traffic levels due to heavy burst loses. In this disser tation we propose and evaluate a congestion management approach we refer to as '"en hanced congestion management" which gears towards rendering and guaranteeing a consistent QoS as well as rational and fair use of available network links. Simulation results show that the scheme can effectively minimize both contention and congestion and at the same time improving both throughput and effective utilization under mod erate to high network traffic loads