1 / 30

Ensuring the QoS Requirements in 802.16 Scheduling

Ensuring the QoS Requirements in 802.16 Scheduling. Alexander Sayenko, Olli Alanen, Juha Karhula, Timo Hämäläinen Telecommunication laboratory, MIT Department University of Jyväskylä, Finland

medge-hendrix
Download Presentation

Ensuring the QoS Requirements in 802.16 Scheduling

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ensuring the QoS Requirements in 802.16 Scheduling Alexander Sayenko, Olli Alanen, Juha Karhula, Timo Hämäläinen Telecommunication laboratory, MIT Department University of Jyväskylä, Finland 9th ACM international symposium on Modeling analysis and simulation of wireless and mobile systems (MSWiM 2006)

  2. Outline • Introduction • Our Scheduling Proposal • Allocation of the minimum number of slots • Allocation of unused slots • Order of Slots • Simulation • Scenario 1 • Scenario 2 • Conclusion

  3. Introduction • WiMAX is an IEEE standard for the wireless broadband access networks • The main advantages • Longer Range • More sophisticated QoS supports at MAC layer

  4. Introduction • 802.16d defines two basic operational modes • Point-to-Multipoint(PMP) Mode • SSs are only allowed to communicate through the BS • Mesh Mode • SSs can communicate to each other and to the BS

  5. Introduction • WiMAX is connection-oriented • SS must register to BS before starting to send or receive data • During registration, SS can negotiate the initial QoS requirements with BS • QoS requirements can be changed later, and a new connection may be established on demand

  6. Introduction • To provide the QoS guarantees in WiMAX network • BS has to translate the QoS requirements of SSs into the appropriate number of slots • BS makes a scheduling decision and informs all SSs by UL-MAP and DL-MAP • Define explicitly slots that are allocated to each SS in both directions

  7. Introduction • However, • The Scheduling Policy is not defined in the WiMAX specifications but rather is open for alternative implementations • Purpose • Design a scheduling solution for the WiMAX BS

  8. Our scheduling proposal • Scheduling should comprise three major stages • Allocation of the minimum number of slots (mandatory) • Allocation of unused slots • Order of Slots

  9. Allocating the minimum number of slots • Ni: number of slots within each frame to ensure the bandwidth requirement of connection i The bandwidth requirement of the ith connection (Byte/sec) The number of bytes a connection can send in one slot (Byte/slot) The number of frames the BS sends per one second (frame#/sec)

  10. Allocating the minimum number of slots • Terms • Bimin: minimum bandwidth requirements • Bimax: maximum bandwidth requirements • Ci: ith connection class • Ri: request size

  11. Allocating the minimum number of slots • UGS • Do not send bandwidth requests • Cannot participate in the contention

  12. Allocating the minimum number of slots • rtPS • Based on the bandwidth requirements and the request size

  13. Allocating the minimum number of slots • ertPS • To combine efficiency of the UGS and rtPS classes

  14. Allocating the minimum number of slots • nrtPS • Can participate in the contention

  15. Allocating the minimum number of slots • BE • Not have any requirements at all

  16. Allocating free slots • It makes sense to allocate unused slots to rtPS, nrtPS, and BE connection • There is no need to allocate slots to UGS or ertPS connection • It is not likely that the constant-rate applications will increase transmission rate

  17. Allocating free slots • Ffree: number of free slots that remains after ensuring minimum bandwidth guarantees • A: a set with connections for which free slots should be assigned

  18. Order of slots • Interleaving the slots to decrease the maximum jitter and delay values

  19. Order of slots • Calculate the ideal distance between slots for every connection • Take all the connections one by one and assign slots to the proper positions • Start to place slots for UGS connections and then for ertPS and rtPS connections • If the chosen slot is already assigned to another connection, then the closest free slot is chosen • The remaining slots can be filled with the slots for the nrtPS and BE connections

  20. Order of slots • By allocating slots in several bursts • Size of the UL-MAP or DL-MAP messages increases • Fewer number of slots available for user data

  21. Simulationscenario 1 • Purpose • ensure that scheduler at BS allocates resource fairly between BE connections regardless of their number • Environment • One BS and 15 SSs that use BE connection • All SSs use the same modulation, 64-QAM ¾ • An SS hosts one FTP application that sends data over TCP protocol to the wired node

  22. Total Throughput

  23. Simulationscenario 2 • Purpose • Test how scheduler at BS allocates resources between connections that belong to different services classes • Environment • One BS and 7 SSs • All SSs use 64QAM ¾ modulation

  24. Simulationscenario 2 • UGS connection is always provided the sufficient number of slots

  25. Simulationscenario 2 • ertPS connection’s throughput is determined by ON/OFF model • During active phase • 80,000 bps • During silence phase • 0 • The scheduler allocates one slots so that this connection can send the bandwidth request as soon as possible

  26. Simulationscenario 2 • rtPS connections’ throughput is determined by the variable-rate IPTV source data • Not experience packet drops during a simulation run

  27. Simulationscenario 2 • nrtPS connections try to send as much data as possible • nrtPS connections’ throughput never exceeds the maximum bandwidth

  28. Simulationscenario 2 • BE connection’s throughput is explained by the amount of free resource left • Determined predominantly by the variable rate of rtPS connections

  29. Conclusion • A scheduling solution for 802.16 BS to ensure QoS requirements of SSs in both directions • Based conceptually on the round-robin scheduling which is fast and simple • Simplify the translation of the QoS requirements into the number of slots • Take into account parameters • minimum/maximum bandwidth requirements, class type, slot size, and the bandwidth request size • Account for WiMAX network parameters • Frames-per-second and modulation

  30. Conclusion • Algorithms on how to allocate free slots and order the slots to decrease the jitter • Further studies • Make our scheduling more flexible in terms of providing the delay and jitter guarantees • Used as constraints at the interleaving stage • Determine the maximum distance between two consecutive slots within the frame

More Related