Considerations on Subframe MAP Design IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number: IEEE S802.16m-08/493 Date Submitted: 2008-05-09 Source: Youngsoo Yuk (sixs@lge.com) Kiseon Ryu (ksryu@lge.com) Ronny (Yong-Ho) Kim (ronnykim@lge.com) LG Electronics *<http://standards.ieee.org/faqs/affiliationFAQ.html> Venue: (Macau, China, May 2008) Base Contribution: IEEE C802.16m-08/493 Purpose: Discussion 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: <http://standards.ieee.org/guides/bylaws/sect6-7.html#6> and <http://standards.ieee.org/guides/opman/sect6.html#6.3>. Further information is located at <http://standards.ieee.org/board/pat/pat-material.html> and <http://standards.ieee.org/board/pat >.

Overall Downlink Control Structure Superframe Header PBCH SBCH SCH Superframe (20ms) Subframe MAP BSD BSDI Frame (5ms) Data for UL Grant PBCH : Network-wide common (Type 2a) SBCH : Sector-specific (Type 2b) BSD : Remaining essential (Type 2c),Extended SCI (Type 3) Note : The period of SCH is TBD (pending #55 meeting)

Design Considerations on Subframe MAP Multiplexing Scheme TDM vs. FDM vs. Hybrid TDM/FDM Transmission Scheme Separate Coding vs. Joint Coding Rate Control vs. Power Control

Multiplexing Comparison TDM FDM Advantages Short feedback delay MS power saving with microsleep Simple separation of data & control region especially on MBS subframe Low MS complexity with small required buffer size High frequency diversity Frequency selective allocation gain High granularity of the ratio between the control channel and the data channel Relatively low unused subcarriers. Better MAP coverage by power sharing with the data channel Drawbacks Low granularity of the ratio between the control channel and the data channel Coverage/throughput loss due to large unused subcarriers Relative long feedback latency (upto 1ms) Large required buffer size for MS Cannot apply microsleep Selectivity loss for localized subchannel comes from pre-allocated control RB Hard to achieve frequency selective gain Low MS Complexity Power Saving Relatively Low Latency Simple Control/Planning Localized/Diversity allocation High granularity Power balancing Better Coverage

Problem of FDM Processing Delay Feedback Latency (a) TDM (b) FDM MAP Decoding FFT Demodulation DeMUX, DeInterleaving, HARQ Combining Burst Decoding (a) TDM (b) FDM DL:UL Ratio Delay (TDM) Delay (FDM) Difference (ms) 5:3 1.6 2.6 1 4:4 1.85 4:4 (2 switching point) 2.78 0.93 6:2 2.47 3.29 0.82 FDD 1.23 0.62

Problem of FDM Required Buffer Size Microsleep/Power Saving Configuration TDM (1 OFDMA symbol) (2 OFDMA symbols) FDM (6OFDMA symbols) Additional buffer size for FDM 4 symbol-buffering 5 symbol-buffering 9~10 symbol-buffering 5~6 symbols 10 MHz, 2 Rx Antennas 17 KB 21 KB 38 ~ 42 KB 21 ~ 25 KB 20 MHz, 2 Rx Antennas 34 KB 42 KB 76 ~ 84 KB 42 ~ 50KB 20 MHz, 4 Rx Antennas 67.5 KB 84.4 KB 152 ~ 169 KB 84.4 ~ 101 KB MAP FFT Demodulation Decoding (a) TDM and Hybrid TDM/FDM (b) FDM Baseband Power Saving Microsleep (RF)

Problem of TDM Resource Waste (Unused resource) Low granularity of TDM Cannot share the resource with data (Power Trading) Power Trading of FDM : Enhance MAP coverage However, Large Power Trade  CQI mismatch, Interference SubMAP Flexible Allocation Power Trade 1 RB 1 RB SubMAP SubMAP … … 1 RB 1 RB 1 RB Unused Unused (a) TDM (Total SubMAP size < 1 symbol) (b) TDM (Total SubMAP size > 1 symbol) (c) FDM

Hybrid TDM/FDM Enhancing TDM advantages Supplementary FDM MAP CAU concept Diversity + Localized allocation for control channels Additional TDM Granularity (1 CAU is 2~4 % of total resource) Cell specific Rotation for Interference Mitigation for SFCH Supplementary FDM MAP Enhancing poor resource allocation by adopting FDM for UL control channels FDM MAP is located at the diversity subchannel without reservation. Allocation granularity is 1 RB (1.7% of one subframe) Influence on MS complexity No Buffering Problem This problem is related only to DL MAP Microsleep UL grant is the response for UL request  MS can know if UL grant exists or not Some UL grants can be located in TDM region  Possible to microsleep

Hybrid TDM/FDM TDM Allocation : CAU (Control Allocation Unit) 3 ~ 8 CAUs/subframe ( if 10MHz: 16CRUs/CAU ~ 6CRUs/CAU ) Remained CAU can be allocated to data or remained empty for interference mitigation Each CAU can be localized or diversity Different Rotation is applied to each cell … Uplink Subframe MAP (Supplementary) Subframe MAP (Downlink /Uplink) SFCH Data Bursts Subchannels Time 1 OFDMA Symbol (b) Logical Subchannel (a) Physical CRUs CRU (18x1) Diversity Mapping Localized CAU 1 CAU 2 CAU 3 CAU 4 Permutation …… Cell-specific Rotation (0,1,2,3) Subframe MAPs

Hybrid TDM/FDM FDM Allocation First N diversity subchannel The RB distribution is indicated by SFCH No reservation only for Subframe MAP Data (Diversity Subchannel) … Uplink Subframe MAP (Supplementary) Subframe MAP (Downlink /Uplink) SFCH Data Bursts Subchannels Time 1 OFDMA Symbol (b) Logical Subchannel (a) Physical RB Localized RB 1 RB Distributed RB 1 subchannel Uplink Subframe MAP (Localized Subchannel)

Multiplexing Comparison FDM TDM Hybrid TDM/FDM Processing delay Longer than TDM Same as TDM Microsleep Impossible Possible (2 symbols) Partially Possible (if no FDM UL MAPs) Symbols to be buffered after FFT (Assuming 0.5TTI (3 symbols) for MAP decoding) 9~10 symbols (Additional 21~101KB) 4~5 symbols 4 symbols Frequency Selectivity Gain for MAP Hard to apply Possible Possible with TDM Flexible Resource Usage (Power and Subcarrier) Good Poor Slightly less than FDM Allocation unit/ % ratio w.r.t. one subframe 1 RB/ 2.08% 1 symbol/ 16.67% 1 CAU and 1 subchannel (2~4%) Effects on resource allocation of data channel Some limitations on localized RB No Limitation Overhead for indicating MAP size (Assuming 16%~25% of control overhead) 3~4 bits (8~12 RBs) 0~1 bit (1~2 OFDMA symbols) 2~3 bits (4 CAUs ~ 1 OFDMA symbol + 4 subchannel)

Transmission Scheme Separate Coding vs. Joint Coding  Separate Coding Rate Control vs. Power Control  Rate Control + Power Control (Limited variation) Separate Coding Joint Coding Advantages Band Selection Gain Simple Coding/Decoding Link Adaptation Gain (Power control, AMC) High Coding Gain (CTC) Relatively high diversity gain Low Resource Indication Overhead Drawbacks High Resource Indication Overhead Relatively lower diversity gain than JC High Decoding Complexity Hard to get link adaptation gain (PC, AMC) Cannot adopt band selection gain Variable MAP size Rate Control (Variable MCS) Power Control (Fixed MCS) Advantages Static interference (Easy to control) Can utilize higher-order modulation High Control Granularity Easy to apply the blind decoding Drawbacks Low Control Granularity Hard to blindly decoded Hard to manage interference (Dynamic variation of interference) Require feedback channel for control channel Cannot utilize higher-order modulation

Text Proposal Insert the following text in SDD Chapter 11.x (Physical Layer): 11.x DL Control Structure 11.x.5 Unicast Service Control Channels 11.x.5.2 Multiplexing Scheme for data and unicast service control DL control channels and data are multiplexed in a subframe using a combination of TDM and FDM. One OFDMA symbol is used for default configuration with one subframe. FDM multiplexing scheme is applied only for control channels related to uplink procedure if one OFDMA symbol is not enough to transmit all of the subframe control channels.

Text Proposal Insert the following text in SDD Chapter 11.x (Physical Layer): 11.x.5.4 Transmission Scheme Multiple unicast service control information elements are coded separately and a different MCS can be used for each control information element that is transmitted. Control information common to scheduled users is multicast, and the modulation and coding scheme is informed by SFH.