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DMS Termination Issue

DMS Termination Issue. Authors:. Date: 200 9-07-14. DMS Termination. DMS is terminated by either STA or AP STA may terminate DMS when it leaves the multicast session AP may terminate DMS when the network is overloaded Some issues are occurred when AP terminates DMS

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DMS Termination Issue

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  1. DMS Termination Issue Authors: Date:2009-07-14 Yongho Seok, LGE

  2. DMS Termination • DMS is terminated by either STA or AP • STA may terminate DMS when it leaves the multicast session • AP may terminate DMS when the network is overloaded • Some issues are occurred when AP terminates DMS • Termination by AP is general situation and not corner case • Now the next slides focus that AP terminates DMS Yongho Seok, LGE

  3. DMS Termination Category • Case 1) • The delivery rate of legacy multicast frame is faster than that of DMS converted frame • This situation may be occurred when the STA is in PS mode • When DTIM interval is one beacon interval and STA does not frequently wakeup Beacon Multicast Multicast Multicast Multicast Multicast Multicast DMS converted DMS converted DMS converted AP Legacy STA DMS capable STA Yongho Seok, LGE

  4. DMS Termination Category • Case 2) • The delivery rate of DMS converted frame is faster than that of legacy multicast frame • This situation is very general because the PHY rate of DMS converted frame is more higher than that of legacy multicast frameAlso, when other station is in PS mode, the legacy multicast frame is delivered at DTIM interval Beacon Multicast Multicast Multicast DMS converted DMS converted DMS converted DMS converted DMS converted DMS converted AP Legacy STA DMS capable STA Drop Drop Drop Yongho Seok, LGE

  5. DMS Termination Category • Case 3) • The delivery rate of legacy multicast frame and DMS converted frame is same (But, exactly it is a race condition) • For making this case, AP shall transmit legacy multicast frame and DMS converted frame iteratively and shall use one queue for the multicast and unicast frames (It is really corner case) Beacon Multicast DMS converted Multicast DMS converted Multicast DMS converted Multicast DMS converted Multicast AP Legacy STA DMS capable STA Drop Drop Drop Drop Drop Yongho Seok, LGE

  6. Which problem is occurred in Case 2? • AP terminates DMS because the network is overloaded • After receiving DMS termination message (unsolicited DMS Response frame), the STA starts to receive legacy multicast frame as specified in TGv Draft • But, as shown in Case 2, the STA already received a number of multicast frames by DMS • The received multicast frames after the DMS termination are almost duplicated but the STA doesn’t know which frame is duplicated Yongho Seok, LGE

  7. Which problem is occurred in Case 2? Beacon Multicast 5 Multicast 6 Multicast 7 DMS 10 DMS 11 DMS 12 DMS 13 DMS 14 Unsolicited DMS Response AP Legacy STA DMS capable STA Drop Drop Drop DMS Terminated Beacon Multicast 8 Multicast 9 Multicast 10 Multicast 11 Multicast 12 Multicast 13 Multicast 14 Multicast 15 Multicast 16 AP Legacy STA DMS capable STA Duplicated Duplicated Duplicated Duplicated Duplicated Duplicated Duplicated Yongho Seok, LGE

  8. Which problem is occurred in Case 2? • Last question is how many frames are duplicated • I think that it is absolutely not a little • In previous example, the number of duplicated frames are 7 • The number of duplicated frames may increases as the delivery rate of DMS converted frame is more faster than that of legacy multicast frame • Nobody can say that the number of duplicated frame is a few Yongho Seok, LGE

  9. Conclusion • As shown in previous cases, Case 2 is almost general situation of DMS • When AP terminates DMS, STA already received a lot of DMS converted frames • The difference between transmitted DMS converted frames and transmitted legacy multicast frames is the number of duplicated frame in STA • This issue is not corner case of DMS termination and DMS shall resolve this issue Yongho Seok, LGE

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