IEEE C802.16e-04/213r1. IEEE Broadband Wireless Access Working Group <

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1 Project Ttle IEEE Broadband Wreless Access Workng Group < QoS Management Subheader for Facltaton of Uplnk Schedulng Date Submtted Source(s) Re: Yongjoo Tcha, Yong-Bum Km, Seong-Choon Lee KT Woomyeon-dong, Seocho-gu, Seoul, , Korea Jeong-Hwan Lee, Chung-Gu Kang Korea Unversty 1.5-ka, Anam-dong, Sungbuk-ku, Seoul,, , Korea IEEE P802.16e/D3 Letter Ballot Voce : Fax : malto: yjtcha@kt.co.kr Voce: Fax: malto: ccgkang@korea.ac.kr Abstract Purpose Notce Release Patent Polcy and Procedures Ths contrbuton ntroduces a new type of MAC subheader, whch provdes dynamc QoS parameters for uplnk schedulng. The document s contrbuted to support certan comment on IEEE P802.16e/D3 Letter Ballot. Ths document has been prepared to assst IEEE It s offered as a bass for dscusson and s not bndng on the contrbutng ndvdual(s) or organzaton(s). The materal n ths document s subject to change n form and content after further study. The contrbutor(s) reserve(s) the rght to add, amend or wthdraw materal contaned heren. The contrbutor grants a free, rrevocable lcense to the IEEE to ncorporate materal contaned n ths contrbuton, and any modfcatons thereof, n the creaton of an IEEE Standards publcaton; to copyrght n the IEEE s name any IEEE Standards publcaton even though t may nclude portons of ths contrbuton; and at the IEEE s sole dscreton to permt others to reproduce n whole or n part the resultng IEEE Standards publcaton. The contrbutor also acknowledges and accepts that ths contrbuton may be made publc by IEEE The contrbutor s famlar wth the IEEE Patent Polcy and Procedures < ncludng the statement "IEEE standards may nclude the known use of patent(s), ncludng patent applcatons, provded the IEEE receves assurance from the patent holder or applcant wth respect to patents essental for complance wth both mandatory and optonal portons of the standard." Early dsclosure to the Workng Group of patent nformaton that mght be relevant to the standard s essental to reduce the possblty for delays n the development process and ncrease the lkelhood that the draft publcaton wll be approved for publcaton. Please notfy the Char <malto:char@wrelessman.org> as early as possble, n wrtten or electronc form, f patented technology (or technology under patent applcaton) mght be ncorporated nto a draft standard beng developed wthn the IEEE Workng Group. The Char wll dsclose ths notfcaton va the IEEE web ste < 0

2 QoS Management Subheader for Facltaton of Uplnk Schedulng Yongjoo Tcha, Yong-Bum Km, Seong-Choon Lee KT Jeong-Hwan Lee, Chung-Gu Kang Korea Unversty 1. Introducton As a demand on multmeda messages and nteractve vdeo applcatons s expected to emerge n the near future, some means of provdng QoS-aware uplnk resource management wll become essental. In general, the base staton scheduler does not have drect access to the ndvdual user s dynamc QoS parameters. In order to support the QoS schedulng for the uplnk, therefore, the relevant parameters must be readly avalable va sgnalng over the uplnk. Ths document proposes to ntroduce another MAC subheader, ncludng the dynamc QoS parameter, whch can be pggybacked wth the uplnk payload as some other subheaders. As addtonal subheader s just a stand-alone message, t does not change any part of the exstng specfcaton, whle provdng varous dynamc QoS parameters n a flexble manner to facltate any type of schedulng algorthm that may be mplemented n the future. 2. Problem Statements When the dfferent users see channels of dfferent capactes for a tme-varyng wreless channel as n IEEE e standard, a packet schedulng algorthm s an essental means of provdng QoS dfferentaton among users whle achevng effcent resource utlzaton. In fact, t s a common practce to employ some type of the packet schedulng algorthm to determne whch user to be served n order, on the bass of the PHY mode and some QoS-related parameters. Proportonal farness (PF) algorthm s one of the most popular wreless packet schedulng algorthm, commonly employed for a broadband wreless packet data system, e.g., cdma00 1x EV-DO. We note that most of the schedulng algorthm s based on some sort of dynamc parameters, whch reflect the urgency of the current packet and/or the nstantaneous data rate to be supported at the moment. For example, the PF algorthm reles on the dynamc rate control (DRC) or equvalently, channel qualty ndcator (CQI), whch s perodcally reported by ndvdual termnal, and the average data rate served so far. Gven these two parameters, throughput can be optmally traded off wth farness, gvng each user roughly equal ar tme. Denotng the dynamc rate control at tme t for user by DRC (t) and the average data rate provded for user by R () t, the PF algorthm s summarzed as follows: Intalzaton: at at tme tme slot slot t t = 0, 0, set set R (0) (0) = 0 for for all all Schedulng: at at tme tme t, t, select for for transmsson the the user user * * wth wth the the smallest value of of δ (t)=drc δ (t)/r (t)/r (t) (t) * * = arg max δ ( t) Updatng: For For from from 1 to to K, K, R (t+1) (t+1) = (1-1/t (1-1/t c ) R c ) R (t)+1/ (t)+1/ t c DRC t c DRC (t) (t) { } In the above, δ () t denotes the prorty metrc for user, governng whch user to be served ahead of the others. Other than PF algorthm, some algorthm deals wth the latency of ndvdual user, especally for those who are 1

3 senstve to the packet delay. One partcular example s the modfed LWDF (Largest Weghted Delay Frst) algorthm [3], whch takes the average delay of each user nto account, now wth the followng prorty metrc: δ () t = adrc() tw() t R () t where W () t denote the average delay of user and a s a constant. Note that t provdes a good tradeoff between farness and effcency subject to delay constrant W() t > T n the sense that Pr( W( t) > T) ε. As far as the downlnk s concerned, all those parameters, e.g., W () t and R () t, to determne the prorty metrc for the gven schedulng algorthm are mmedately avalable n the base staton. Most of the prevous studes on the packet schedulng algorthm are concerned wth the downlnk only, smply because downlnk effcency s crtcal to support broadband nternet traffc concentrated toward downlnk. As a demand on multmeda messagng and nteractve vdeo applcatons ncreases, however, uplnk schedulng wll be an essental means of provdng QoS-aware resource management for uplnk. As all users are spatally dstrbuted wthout knowng the bandwdth requrement of ndvdual user, the relevant nformaton must be frequently reported toward the base staton so as to schedule the uplnk utlzaton. In the current standard, only means of reportng the ndvdual user s bandwdth requrement s the bandwdth request (BR) message, delvered ether through a BR header, whch s a specal type of MAC header, or a grant management (GM) subheader, whch s pggybacked wth the uplnk payload. All these headers quantfy the bandwdth request n the number of bytes that are requred by the correspondng user. We note the BR s a quantty merely to represent the queue length or changes n the queue length. As the queue length s just an ndrect measure of ndcatng the current traffc demand or load, t cannot be explctly used to deal wth QoS requrement, especally for the delay-senstve or loss-senstve applcatons. In the modfed LWDF algorthm, for example, the average delay experenced by ndvdual user must be perodcally reported to the base staton scheduler. Some algorthm requres two or more dynamc parameters, e.g., queue length and resdual lfetme [4]. In summary, the current standard does not specfy any effectve means of provdng dynamc QoS parameters that may be requred for uplnk QoS schedulng, dependng on the type of uplnk packet schedulng algorthm. As the packet schedulng algorthm s just a choce of mplementaton, the standard must be flexble enough to accommodate any type of schedulng algorthm. 3. Proposed Changes To support the uplnk QoS parameters, a QoS management (QM) subheader s defned as an addtonal subheader. One reserved bt that s now a QoS management bt can be used to ndcate the presence of the QM subheader. As the reserved bt s used, the exstng format of MAC header s not subject to any change. If the QoS management bt s set, dynamc QoS Parameters shall be transported by a QoS management subheader. The format of the QoS Management subheader s specfed n Table 14. Remedy 1: [Change the fgure 19 n the baselne document Secton Generc MAC header n page 37. ] 2

4 HT=0(1) msb EC(1) Type (6) QM(1) CI(1) EKS (2) Rsv(1) LEN msb (3) LEN lsb (8) CID msb (8) CID lsb (8) HCS (8) P 37. Fgure 19 Generc MAC header format Remedy 2: [Add the followng tables to the baselne document Secton MAC subheaders and specal payloads n page 43. ] QoS Management subheader If the QoS management bt n the MAC Type feld (see Table 6) s set, dynamc QoS Parameters shall be transported byqos management subheader. The format of the QoS Management subheader s specfed n Table 14. QoS Management Subheader( ) { Table 14. QoS Management subheader format Syntax Sze Notes No. Parameters 2 bts The number of parameters for ( = 0 ; < No. Parameter ; ++) { Dynamc QoS Parameters 4 bts } If!( byte boundary ) { Paddng nbbles Varable } } 4. Effect of Uplnk QoS Schedulng: Illustraton 3

5 To llustrate how the dynamc QoS parameters play an essental role of mprovng the system performance over the uplnk, some results n [4] are quoted here. The contenton-free dstrbuted dynamc reservaton MAC protocol wth determnstc schedulng (C-FD 3 R MAC) algorthm s a typcal example of contenton-free mechansm of the reservaton request and a moble-asssted (dstrbuted) uplnk schedulng under a framework of dynamc reservaton TDMA as n IEEE standard. We note that t s mplemented wth two dfferent dynamc parameters, the estmated resdual lfetme and queue length. The proposed approach s compared wth dynamc slot assgnment (DSA++) algorthm, proposed n the context of wreless ATM. To show how much performance gan can be affected by the schedulng algorthm and by the choce of dfferent dynamc parameters, smulaton results and analyss are quoted from [4] as follows: The desgn objectve of C-FD 3 R scheme s to guarantee the real-tme constrant of rt-vbr traffc class whle maxmzng the multplexng gan among all ATM traffc classes. In other words, all rt-vbr traffc class s subject to delay constrant,.e., the cell transfer delay not to exceed the delay bound max_ctd. Fgures 1 and 2 show the cell transfer delay and cell loss rato of rt-vbr traffc versus the number of WT s offered for rt-vbr respectvely. In Fgures 1 and 2, a value nsde a crcle denotes the number of WT s offered for nrt-vbr. As can be seen from Fgure 1, the C-FD 3 R system mantans the cell transfer delay of rt-vbr sesson constant wthn the delay bound (max_ctd = 30 ms), regardless of the number of WT s offered n the system. For the DSA++ system, meanwhle, the correspondng cell transfer delay ncreases steadly as the number of WT s offered for rt-vbr ncreases and ultmately, t exceeds the delay bound. The correspondng performance gan of the C- FD 3 R system s further manfested by the cell loss rato, as presented n Fgure 2. The cell loss rato for rt-vbr n the C-FD 3 R system s sgnfcantly low as compared wth that for the DSA++ system. Furthermore, t s not affected by the number of WT s offered for nrt-vbr. From Fgures 1 and 2, t obvous that the C-FD 3 R system outperforms the DSA++ system n both delay and cell loss for rt-vbr traffc. Cell Transfer Delay of rt-vbr traffc (ms) max CTD C-FD 3 R DSA++ The number WT's offered for nrt-vbr The number of WT's offered for rt-vbr Fgure 1. Cell Transfer Delay of rt-vbr traffc vs. the Number of WT s Offered for rt-vbr 4

6 Cell Loss Rato of rt-vbr traffc C-FD 3 R DSA++ The number of WT's offered for nrt-vbr The number of WT's offered for rt-vbr Fgure 2. Cell Loss Rato of rt-vbr Traffc vs. the Number of WT s Offered for rt-vbr 5. References [1] IEEE P802.16e/D3-04 Amendment for Physcal and Medum Access Control Layers for Combned Fxed and Moble Operaton n Lcensed Band. [2] IEEE P REVd/D5-04 Ar Interface for Fxed Broadband Wreless Access Systems [3] Matthew Andrews, Krshnan Kumaran, Kavta Ramanan, Alexander Stolyar, and Phl Whtng, Rajv Vjayakumar, "Provdng Qualty of Servce over a Shared Wreless Lnk," IEEE Communcatons Magazne, pp0-4, February 01. [4] Chung Gu Kang, Chang Wook Ahn, Kyung Hun Jang, and Woo Sk Kang, Contenton-Free Dstrbuted Dynamc Reservaton MAC Protocol wth Determnstc Schedulng (C-FD3R MAC) for Wreless ATM Networks, IEEE Journal of Selected Areas n Communcatons, Vol. 18, No. 9, p.1623~1635, September 00. 5