A Dual Feedback Approach of Request-based Bandwidth Allocation for Real-time Service in Broadband Wireless Access Networks

Eun-Chan Park and Hwangnam Kim

Dept. of Information and Communication , Dongguk University()Dept. of Electrical Engineering, Korea University()

IEEE Transactions on Communications, Vol. 57, No. 3, March, 2009 A Dual Feedback Approach of Request-based Bandwidth Allocation for Real-time Service in Broadband Wireless Access NetworksAgendaIntroductionOptimal bandwidth-request algorithm for ertPSAnalysis of the proposed algorithmConclusionIntroductionFive types of bandwidth allocation mechanismUnsolicited Grant Service (UGS)Real-time polling service (rtPS)Non-real-time polling service (nrtPS)Best effort (BE)Extened real-time polling service (ertPS)

Bandwidth request allocation mechanism No specific mechanism has been standardized Impacts the bandwidth utilization and delay constraints Optimal bandwidth-request algorithm for ertPSAssumptionsUplink traffic considerationBS employs a priority-based scheduler to serve real-time servicesIf the real-time services are admitted, the services are served with the guaranteed bandwidth Bandwidth-allocation interval Ta is equal to packetization intervalNo queuing delay at BSOptimal bandwidth-request algorithm for ertPSDual feedback approach of bandwidth request mechanismComputes total additional bandwidth-request B(t)Takes the following two metrics into considerationsQueue size difference eq(t)Rate mismatch er(t)Optimal bandwidth-request algorithm for ertPSTarget delay (sec.), TrefTolerable MAC-to-MAC delay for real-time applicationsDelay incurred in application layer is not included

Target transmission queue length in SS (bytes), Qref

Average packet sizeAdditional delay ( processing delay at MAC, transmission delay over wireless link)Bandwidth allocation interval Optimal bandwidth-request algorithm for ertPSDemonstration of ideal case: Qref=q(t)TimeBSTimeSSTrefbbbP1P2P1P2P3P3TaTaTo

P1Data packetbBW request packetq(t)=3ToToOptimal bandwidth-request algorithm for ertPSDemonstration of ideal case: Qref>q(t)TimeBSTimeSSTrefbbbP1P2P1P2P3P3To

P1Data packetbBW request packetq(t)=3ToTobTaTaTaP3P2P1Excessive bandwidth allocationOptimal bandwidth-request algorithm for ertPSDemonstration of ideal case: Qref0 Queue length growser(t)=a(t)-s(t)