The paper proposes air architecture for a scheduling algorithm, to be integrated in IEEE 802.11 Access Points (AP), able to take into account, besides the transport service class required by the destination user, the channel quality experimented by the destination mobile STAtion (STA). The relevance of this topic is due to the observation that when one or more STAs experiment poor radio channel conditions, they increase the time spent to transmit a single packet, due to the retransmission of corrupted frames and the adoption of a transmission techniques at lower bit rate, leading to an inefficient use of the shared medium. These phenomena have as a consequence the worsening of the performance of all the STAs sharing the wireless medium independently of their radio channel conditions. The adoption of a scheduling algorithm able to manage information on channel quality permits to reduce these effects, not penalizing the STAs experimenting good channel condition and, as a consequence, their experimented throughput. As a result, only the STAs in bad channel conditions experiment a reduction of throughput. A prototype of an AP equipment implementing the proposed architecture is then presented; it has been obtained modifying the Hierarchical Token Bucket (HTB) and has been indicated as Wireless Hierarchical Token Bucket (WHTB). The performance of the presented prototype are experimentally evaluated and compared with those obtained with standard scheduling algorithm, which do not take into account information on channel quality.

The Wireless Hierarchical Token Bucket: a Channel Aware Scheduler for 802.11 Networks

GARROPPO, ROSARIO GIUSEPPE;GIORDANO, STEFANO;
2005-01-01

Abstract

The paper proposes air architecture for a scheduling algorithm, to be integrated in IEEE 802.11 Access Points (AP), able to take into account, besides the transport service class required by the destination user, the channel quality experimented by the destination mobile STAtion (STA). The relevance of this topic is due to the observation that when one or more STAs experiment poor radio channel conditions, they increase the time spent to transmit a single packet, due to the retransmission of corrupted frames and the adoption of a transmission techniques at lower bit rate, leading to an inefficient use of the shared medium. These phenomena have as a consequence the worsening of the performance of all the STAs sharing the wireless medium independently of their radio channel conditions. The adoption of a scheduling algorithm able to manage information on channel quality permits to reduce these effects, not penalizing the STAs experimenting good channel condition and, as a consequence, their experimented throughput. As a result, only the STAs in bad channel conditions experiment a reduction of throughput. A prototype of an AP equipment implementing the proposed architecture is then presented; it has been obtained modifying the Hierarchical Token Bucket (HTB) and has been indicated as Wireless Hierarchical Token Bucket (WHTB). The performance of the presented prototype are experimentally evaluated and compared with those obtained with standard scheduling algorithm, which do not take into account information on channel quality.
2005
0769523420
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/188938
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