1. C80216m-08_245 ProjectIEEE 802.16 Broadband Wireless Access Working Group http://ieee802.org/16 TitleComments on Frame Structure Date Submitted 2008-03-17 Source(s)Kevin Power, Sunil Vadgama, Chris Williams Keiichi Nakatsugawa, Masato Okuda, Dorin Viorel E-mail: kevin.power@uk.fujitsu.com sunil.vadgama@uk.fujitsu.com chris.williams@uk.fujitsu.com nakatsugawa@jp.fujitsu.com okuda@jp.fujitsu.com DViorel@fmci.fujitsu.com Re:Call for Comments/Contributions on C802.16m-08-118r1 AbstractThis contribution proposes some text for section 11.4.2 Frame Structure when supporting legacy frames (proposal 1 and proposal 2) which captures the input from row 21 of the consolidated spreadsheet (08/096r1), in that, more than two switching points shall be possible when supporting legacy. PurposeFor discussion and approval by TGm Notice This document does not represent the agreed views of the IEEE 802.16 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 IEEE ’ s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE ’ s 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 802.16. Patent Policy The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and.http://standards.ieee.org/guides/bylaws/sect6-7.html#6http://standards.ieee.org/guides/opman/sect6.html#6.3 Further information is located at and.http://standards.ieee.org/board/pat/pat-material.htmlhttp://standards.ieee.org/board/pat

2. C80216m-08_245 2 Introduction This contribution raises some concerns we have with respect to the Baseline Frame Structure contribution C802.16m-08/118r1. In particular, we focus on section 11.4.2 (proposal 1 and proposal 2) which concerns legacy support when both legacy and.16m are operating on the same RF carrier with same channel bandwidth. We highlight some key issues that must be captured within the particular proposals in order for TGm discussions to move forward.

3. C80216m-08_245 3 Issues with section 11.4.2 – Proposal 1

4. C80216m-08_245 4 Switching Points This proposal explicitly states; There shall be only two switching points in each TDD radio frame when supporting legacy systems. We feel that this sentence unnecessarily constrains the performance of 16m and therefore should be removed or modified to; In the case of coexistence with legacy systems, two switching points may be selected in each TDD radio frame. Rational; 1.It automatically disables the “fast feedback structure” for.16m terminals when supporting legacy systems  feedback every 2.5ms 2.The matter of co-existence is deployment dependent  if there is no coexistence problem with legacy then >2SPs should be supported  When using >2SP supporting legacy terminals, the neighbour systems can be organised without causing mutual interference. (eg: by aligning the SPs)

5. C80216m-08_245 5 Switching Points The number of switching points should not be limited to two There seems to be strong interest from row 21 of the consolidated spreadsheet, in that, >2SPs may be introduced even when supporting legacy We understand the coexistence issues and the interference issues >2SPs may cause. However, it can be resolved, for example: 1.Allow only 2 SPs when coexisting with legacy systems (but only in the coexistence scenario) 2.Partially puncture the legacy system (not preferable) Number of Switching Points when supporting legacy max. 2possibly >2 # of supporters 1012

6. C80216m-08_245 6 Fast Feedback We need to be able to support fast feedback for.16m terminals as well as supporting legacy terminals when both are operating on the same RF carrier. It is clear from the proposals submitted to session #53, that fast feedback should be enabled when legacy support is not required as there can be clear benefits such as; –Increased support for high mobility users –Increased efficiency for closed loop feedback schemes –Increased frequency of ACK/NACK feedback (reducing H-ARQ latency) –Reduced frame alignment required However, when legacy support is enabled, do we want to unnecessarily take this feature (fast feedback) away from the 16m terminals?

7. C80216m-08_245 7 Issues with section 11.4.2 – Proposal 2

8. C80216m-08_245 8 Clarification The above Figure is not clear and does not complement the text. Some concerns regarding the above are; What is the purpose of the 16m Sub-frame that follows the 16m DL- subframe, (highlighted in blue)? –Can it be allocated either DL or UL? –If it is allocated UL then this proposal barely differs from Proposal-1 Is the 16m Zone (highlighted in pink) restricted to two subframes? If so, what is the rational behind this?

9. C80216m-08_245 9 Summary –We need to be able to support fast feedback for.16m terminals as well as supporting legacy terminals when both are operating on the same RF carrier. –We should not constrain 16m performance when there is no coexistence issues –Figure and text of proposal 2 is not very clear. Proposed text shown on next slide. –The number of SPs should be configurable by the Operators to meet the requirements, traffic and spectrum allocations. –We should not unnecessarily compromise the 16m performance to satisfy legacy support, therefore, fast feedback must be enabled for 16m MSs when supporting legacy.

10. C80216m-08_245 10 Proposed Text Insert the following text into Frame Structure sub-clause (IEEE C802.16m-08/118r1): --------------------------------------------- Text Start --------------------------------------------------- 11.4.2 Frame Structure Supporting Legacy Frames (proposal-2) When legacy support is enabled, the legacy frames and the 802.16m frames are offset by a fixed integer number of mini-frames to allow accommodate of new designs for 802.16m such as system synchronization signal. As shown in Figure 11.4-3 (proposal-2), the 802.16m frame structure supports the legacy frames by having the legacy portion and the 802.16m portion sharing the 802.16m air link in a time-division manner. Such a legacy frame support scheme is applied to TDD, FDD, and H-FDD duplexing schemes, although Figure 11.4-3 (proposal-2) illustrates the scheme in TDD. It can be noted from Figure 11.4-3, within a 802.16m radio frame, the first subframe shall be assigned to DL as this may contain a synchronisation signal. The subsequent subframe(s) within the 802.16m radio frame could be individually allocated either DL or UL. It should also be noted that, it shall be possible to introduce more than 2 switching points when supporting legacy systems.

11. C80216m-08_245 11 Figure 11.4-3: Frame Structure Supporting Legacy Frames (TDD)  proposal-2 ----------------------------------------------- Text End ---------------------------------------------------