Performance evaluation of an enhanced distributed channel access protocol under heterogeneous traffic

Recently there have been considerable interests focusing on the performance evaluation of IEEE 802.11e Medium Access Control (MAC) protocols, which were proposed for supporting Quality of Services (QoS) in Wireless Local Area Networks (WLANs). Different from most existing work, this study has conducted comprehensive performance evaluation and analysis of the IEEE 802.11e Enhanced Distributed Channel Access (EDCA) protocol in the presence of heterogeneous network traffic including non-bursty Poisson, bursty ON/OFF, and self-similar traffic generated by wireless multimedia applications. The performance results on throughput, access delay and medium utilization have demonstrated that the protocol is able to achieve satisfying QoS differentiation for heterogeneous multimedia traffic. On the other hand the results have showed that IEEE 802.11e EDCA suffering from the low medium utilization due to the overhead generated by transmission collisions and back-off processes. 1

A Dynamic Approach to MIB Polling for Software Defined Monitoring

Technology trends such as Software-Defined Networking (SDN) are transforming networking services in terms of flexibility and faster deployment times. SDN separates the control plane from the data plane with its centralised architecture compared with the distributed approach used in other management systems. However, management systems are still required to adapt the new emerging SDN-like technologies to address various security and complex management issues. Simple Network Management Protocol (SNMP) is the most widespread management protocol implemented in a traditional Network Management System (NMS) but has some limitations with the development of SDNlike services. Hence, many studies have been undertaken to merge the SDN-like services with traditional network management systems. Results show that merging SDN with traditional NMS systems not only increases the average Management Information Base (MIB) polling time but also creates additional overheads on the network. Therefore, this paper proposes a dynamic scheme for MIB polling using an additional MIB controller agent within the SDN controller. Our results show that using the proposed scheme, the average polling time can be significantly reduced (i.e., faster polling of the MIB information) and also requires very low overhead because of the small sized OpenFlow messages used during polling

Connecting Disjoint Nodes Through a UAV-Based Wireless Network for Bridging Communication Using IEEE 802.11 Protocols

Cooperative aerial wireless networks composed of small unmanned aerial vehicles(UAVs) are easy and fast to deploy and provide on the fly communication facilities in situations where part of the communication infrastructure is destroyed and the survivors need to be rescued on emergency basis. In this article, we worked on such a cooperative aerial UAV-based wireless network to connect the two participating stations. The proposed method provides on the fly communication facilities to connect the two ground stations through a wireless access point (AP) mounted on a UAV using the IEEE 802.11a/b/g/n. We conducted our experiments both indoor and outdoor to investigate the performance of IEEE 802.11 protocol stack including a/b/g/n. We envisioned two different cases: line of sight (LoS) and non-line of sight (NLoS). In LoS, we consider three different scenarios with respect to UAV altitude and performed the experiments at different altitudes to measure the performance and applicability of the proposed system in catastrophic situations and healthcare applications. Similarly, for NLoS, we performed a single set of experiments in an indoor environment. Based on our observations from the experiments, 802.11n at 2.4 GHz outperforms the other IEEE protocols in terms of data rate followed by 802.11n at 5 GHz band. We also concluded that 802.11n is the more suitable protocol that can be practiced in disastrous situations such as rescue operations and healthcare applications

A SDN-based On-Demand Path Provisioning Approach across Multi-domain Optical Networks

The interconnection of remote datacentres with optical networks are emerging use cases and such orchestration of multi-domains require the design of new network control, management, and orchestration architectures. Such heterogeneity needs to adopt end-to-end services like on-demand path provisioning. It is acknowledged that such scenarios are more complexed and have fundamental limitations in terms of high performance and delay. To address these issues, and as a means to cope with the complexity growth, research in this area is considering the concept of Software-Defined Network (SDN) orchestration for multi-domain optical networks to coordinated the control of heterogeneous systems. This paper presents a SDN path provisioning approach across Multi-Domain Optical Networks. The aim is to develop an efficient on-demand path provisioning platform in a software defined optical network at the control plane to dynamically manage the network's load, especially in emergency scenarios. The proposed distributed system architecture will help to solve the longstanding problem of inter-domain path provisioning. Our proposed architecture is implemented and validated in a control plane testbed to validate the approach. The paper also evaluated the factors such Quality of Service (QoS) of the network deployment associated with delay or control overhead. Our results show that the method will reduce additional delays in a multi-domain optical network, where high capacity and low latency are requirements for data-intensive applications and cloud services. The proposed method also maintains the total number of flows as low as possible to make the algorithm fast and reduce overheads

Optical Space Switches in Data Centers: Issues with Transport Protocols

A number of new architectures for data centre networks employing reconfigurable, SDN controlled, all-optical networks have been reported in recent years. In most cases, additional capacity was added to the system which unsurprisingly improved performance. In this study, a generalised network model that emulates the behaviour of these types of network was developed but where the total capacity is maintained constant so that system behaviour can be understood. An extensive emulated study is presented which indicates that the reconfiguration of such a network can have a detrimental impact on Transmission Control Protocol (TCP) congestion control mechanisms that can degrade the performance of the system. A number of simple scheduling mechanisms were investigated and the results show that an on-demand scheduling mechanism could deliver a throughput increase of more than ∼50% without any increase in total installed network capacity. These results, therefore, indicate the need to link the network resource management with new datacentre network architectures