A IEEE 802.11e HCCA Scheduler with a Reclaiming Mechanism for Multimedia Applications

Advances in Multimedia ◽

10.1155/2014/372693 ◽

2014 ◽

Vol 2014 ◽

pp. 1-22 ◽

Cited By ~ 6

Author(s):

Anna Lina Ruscelli ◽

Gabriele Cecchetti

Keyword(s):

Traffic Management ◽

Scheduling Algorithm ◽

Multimedia Applications ◽

Service Differentiation ◽

Transmission Time ◽

Ieee 802.11E ◽

Variable Bit Rate ◽

Bit Rate ◽

Positive Effects ◽

Dynamic Update

The QoS offered by the IEEE 802.11e reference scheduler is satisfactory in the case of Constant Bit Rate traffic streams, but not yet in the case of Variable Bit Rate traffic streams, whose variations stress its scheduling behavior. Despite the numerous proposed alternative schedulers with QoS, multimedia applications are looking for refined methods suitable to ensure service differentiation and dynamic update of protocol parameters. In this paper a scheduling algorithm,Unused Time Shifting Scheduler(UTSS), is deeply analyzed. It is designed to cooperate with a HCCA centralized real-time scheduler through the integration of a bandwidth reclaiming scheme, suitable to recover nonexhausted transmission time and assign that to the next polled stations. UTSS dynamically computes with anO(1)complexity transmission time providing an instantaneous resource overprovisioning. The theoretical analysis and the simulation results highlight that this injection of resources does not affect the admission control nor the centralized scheduler but is suitable to improve the performance of the centralized scheduler in terms of mean access delay, transmission queues length, bursts of traffic management, and packets drop rate. These positive effects are more relevant for highly variable bit rate traffic.

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Elastic QoS Scheduling with Step-by-Step Propagation in IEEE 802.11e Networks with Multimedia Traffic

Wireless Communications and Mobile Computing ◽

10.1155/2019/2925891 ◽

2019 ◽

Vol 2019 ◽

pp. 1-23 ◽

Cited By ~ 1

Author(s):

Anna Lina Ruscelli ◽

Gabriele Cecchetti ◽

Piero Castoldi

Keyword(s):

Physical Layer ◽

Service Differentiation ◽

Transmission Time ◽

Ieee 802.11E ◽

Service Needs ◽

Virtual Training ◽

Time Service ◽

Depth Analysis ◽

Feasibility Test ◽

Service Data

The spreading diffusion of wireless devices and the crowded coexistence of multimedia applications greedy of bandwidth and with strict requirements stress the service provisioning offered by wireless technologies. WiFi is a reference for wireless connectivity and it requires a continuous evolution of its mechanism in order to follow increasingly demanding service needs. In particular, despite the evolution of physical layer, some critical contexts, such as industrial networks, telemedicine, telerehabilitation, and virtual training, require further refined improvements in order to ensure the respect of strict real-time service requirements. In this paper an in-depth analysis of Dynamic TXOP HCCA (DTH) MAC enhanced centralized scheduler is illustrated and it is further refined introducing a new improvement, DTH with threshold. DTH and DTH with threshold can be integrated with preexisting centralized schedulers in order to improve their performances, without any overprovisioning that can negatively impact on the admission control feasibility test. Indeed, without modifying the centralized scheduler policy, they combine together the concepts of reclaiming transmission time and statistical estimation of the traffic profile in order to provide, at each polling, an instantaneous transmission time tailored to the variable traffic requirements, increasing, when necessary, the service data rate. These mechanisms can coexist with advanced physical layer-based solutions, providing the required service differentiation. Experimental results and theoretical analysis, based on elastic scheduler theory, show that they are effective especially in the case of Variable Bit Rate traffic streams in terms of transmission queues length, packets loss, delay, and throughput.

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