FDD Frame Structure – RTG and TTG Considerations IEEE Presentation Submission Template (Rev. 9) Document Number: IEEE S802.16maint-08/122 Date Submitted: Source: Jeff Zhuang Pallav Mark Cudak * Venue: IEEE Working Group Letter Ballot Recirc #26b Base Contribution: IEEE C802.16maint-08/122 Purpose: Accept the proposed specification changes on IEEE P802.16Rev2/D3. Notice: This document does not represent the agreed views of the IEEE Working Group or any of its subgroups. It represents only the views of the participants listed in the Source(s) field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEEs name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEEs sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and. Further information is located at and. IEEE S802.16maint-08/122

Timing advance (TA) is applied to the UL subframe so that UL subframes from all mobiles arrive at the BS at the same time. TTG=SSRTG+RTD (i.e., TTG=SSRTG+max_allowed RTD). –Set to TA=0 when MS is at cell edge (i.e., at maximal allowable RTD) Actual switch time allowed= SSRTG –Set to TA=max_RTD when MS is co-located with BS (i.e., actual RTD=0) Actual switch time allowed = SSRTG+RTD=TTG –SSRTG <=50us (TTD) or <=100us (H-FDD) SSTTG (MS can actually get, not required minimal value!) = RTG+RTD –When RTD=0 (co-located), RTG=SSTTG. Must satisfy RTG>=maximal SSTTG Actual switch time allowed = SSTTG –When RTD=max (cell edge) Actual switch time allowed = SSTTG + RTD RTG+TTG>=SSRTG+SSTTG+RTD (equal achieved only when setting RTG=SSTTG) TTG+RTG = 5000 (us) – (#DL symbols + #UL symbols)*Ts (symbol duration) Basic Constraints RTD= round trip delay BS to MS TA= timing advance; this is a delay applied to the UL frame to guarantee that all UL frames arrive at the BS at the same time TTG=transmit to receive transition gap at BS RTG=receive to transmit transition gap at BS SSRTG=mobile station receive to transmit transition gap SSTTG=mobile station transmit to receive transition gap Fixed time, independent of RTD DL at BS (G1) DL at G1-MS DL at BS (G1) DL at MS (G1) RTD/2 TfTf TTG UL at G1-MS RTG SSRTG+TA RTD/2 SSTTG (min=50us) UL at BS (G1) RTD/2 Fixed time from BS perspective, independent of RTD Fixed time, independent of RTD Same apply to Group-2

IEEE S802.16maint-08/122 RTG and TTG switching time Sufficient to investigate group-1 and group-2 separately Basic design: –TTG=SSRTG+RTD –RTG>=SSTTG –TTG+RTG =Frame duration – (#DL symbols + #UL symbols)*Ts (symbol duration) Group-1 from BS perspective: Group-2 from BS perspective: DL Inter-group gap DL Inter-frame gap (shown here =0)

IEEE S802.16maint-08/122 Case #1: Inter-group gap = K*Ts (e.g., K=0) The DL unused time is If there is no inter-group gap, additional constraint must be observed for group-2: –Additional constraint imposes restrictions on the RTD May Lose 1 symbol to accommodate appropriate RTD Group-1 can use T_DL,gap for TTG and RTG as in the current TDD

IEEE S802.16maint-08/122 Case #2: Inter-frame gap = K*Ts (e.g., K=0) TTG+RTG = T f – (#DL symbols + #UL symbols)*Ts No additional constraints on RTD –More flexibility and better utilization

IEEE S802.16maint-08/122 Comparison Case #1: inter-group gap = multiple symbols –BS has an inter-group gap of integer # of symbols –Possibly easier FDD-BS implementation in DL transmission Deal with a non-integer gap at the end of DL frame –Same for full-duplex FDD MS in DL reception Assuming FD-FDD is served in both partitions (not by removing group-2) –But, group-2 MS will have integer symbols gap between its DL and next preamble Case #2: inter-frame gap = multiple symbols –BS needs to have a non-integer inter-group gap Integer # of symbol at the end of DL frame –FD-FDD MS will have to do the same in DL reception –Group-2 MS will have a non-integer gap between its DL and next preamble In case #1, we will lose one more UL symbols for group-2 (see previous slides) Recommendation: Adopt #2

IEEE S802.16maint-08/122 Proposed text I: Add the following text after line 49 pg 678 Section The time gap between the DL transmission period for the first group and the DL transmission period for the second group is: where is an integer number of OFDMA symbols and is the remaining time after the maximum number of integer symbols are accommodated in a OFDMA frame, i.e., II: Add the row shown in Red to Table 543 pg 1067 Section Name TypeType Lengt hValue(variable length) PHY scope Indicates the number of integer OFDMA symbols between the two OFDMA DL subframes in H-FDD OFD MA