1,453 research outputs found
Software Defined Networks based Smart Grid Communication: A Comprehensive Survey
The current power grid is no longer a feasible solution due to
ever-increasing user demand of electricity, old infrastructure, and reliability
issues and thus require transformation to a better grid a.k.a., smart grid
(SG). The key features that distinguish SG from the conventional electrical
power grid are its capability to perform two-way communication, demand side
management, and real time pricing. Despite all these advantages that SG will
bring, there are certain issues which are specific to SG communication system.
For instance, network management of current SG systems is complex, time
consuming, and done manually. Moreover, SG communication (SGC) system is built
on different vendor specific devices and protocols. Therefore, the current SG
systems are not protocol independent, thus leading to interoperability issue.
Software defined network (SDN) has been proposed to monitor and manage the
communication networks globally. This article serves as a comprehensive survey
on SDN-based SGC. In this article, we first discuss taxonomy of advantages of
SDNbased SGC.We then discuss SDN-based SGC architectures, along with case
studies. Our article provides an in-depth discussion on routing schemes for
SDN-based SGC. We also provide detailed survey of security and privacy schemes
applied to SDN-based SGC. We furthermore present challenges, open issues, and
future research directions related to SDN-based SGC.Comment: Accepte
Priority-Oriented Adaptive Control With QoS Guarantee for Wireless LANs.
In today’s wireless networks there is a great need
for QoS, because of the time-bounded voice, audio and video
traffic. A new QoS enhanced standard is being standardized by
the IEEE 802.11e workgroup. It uses a contention free access
mechanism called Hybrid Control Channel Access (HCCA) to
guarantee QoS. However, HCCA is not efficient for all types of
time-bounded traffic. This work proposes an alternative protocol
which could be adapted in HCF (Hybrid Coordination Function).
The Priority Oriented Adaptive Control with QoS Guarantee
(POAC-QG) is a complete centralized channel access mechanism,
it is able to guarantee QoS for all types of multimedia network
applications, it enhances the parameterized traffic with priorities,
and it supports time division access using slots. Furthermore, it
instantly negotiates the quality levels of the traffic streams
according to their priorities, supporting multiple streams to the
best quality it can achieve. POAC-QG compared to HCCA,
provides higher channel utilization, adapts better to the
characteristics of the different traffic types, differentiates the
traffic streams more efficiently using priorities, and generally
exhibits superior performance
CA-AQM: Channel-Aware Active Queue Management for Wireless Networks
In a wireless network, data transmission suffers from varied signal strengths and channel bit error rates. To ensure successful packet reception under different channel conditions, automatic bit rate control schemes are implemented to adjust the transmission bit rates based on the perceived channel conditions. This leads to a wireless network with diverse bit rates. On the other hand, TCP is unaware of such {\em rate diversity} when it performs flow rate control in wireless networks. Experiments show that the throughput of flows in a wireless network are driven by the one with the lowest bit rate, (i.e., the one with the worst channel condition). This does not only lead to low channel utilization, but also fluctuated performance for all flows independent of their individual channel conditions.
To address this problem, we conduct an optimization-based analytical study of such behavior of TCP. Based on this optimization framework, we present a joint flow control and active queue management solution. The presented channel-aware active queue management (CA-AQM) provides congestion signals for flow control not only based on the queue length but also the channel condition and the transmission bit rate. Theoretical analysis shows that our solution isolates the performance of individual flows with diverse bit rates. Further, it stabilizes the queue lengths and provides a time-fair channel allocation. Test-bed experiments validate our theoretical claims over a multi-rate wireless network testbed
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