Document Number: IEEE C80216m-09_2238r2 Date Submitted: 2009-11-17 CoFIP Pilot Structure Document Number: IEEE C80216m-09_2238r2 Date Submitted: 2009-11-17 Source: Padmanabhan M S, Kiran Kuchi, J. Klutto Milleth, Sivakishore Voice: CEWiT, India E-mail: kkuchi@cewit.org.in, klutto@cewit.org.in Venue: Comments on P802.16m/D2 (15.3.5.4.1) Base Contribution: None Purpose: To discuss and adopt the proposed text in D3 To discuss in TGm for appropriate action. 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 >.

Collision Free Interlaced Pilots (CoFIP)

Outline In Jeju it was agreed that CoFIP will be used for CDR. Details of CoFIP are TBD. In this contribution details of CoFIP pilot structure are given In 2253, 2-stream pilot-on-data is proposed. Performance of both methods compared CoFIP is shown to be more than 2.0-2.5 dB better than 2-stream pilot-on-data using a low-complexity MMSE receiver Proposed text

Proposed CoFIP P denotes pilot tone and 0 denotes null tone P P Pilot pattern Set 0 Pilot pattern Set 1 Pilot pattern Set 2 P denotes pilot tone and 0 denotes null tone

Pilot structure proposed in S80216m-09_2253

Simulation setup 1 2Tx antenna – 2Rx antenna, one stream CDR transmission Channel: Modified Ped B, 30 km/h Thermal noise level is 30 dB below the power of the desired signal QPSK ½ CTC , eight 18x6 PRUs forms a channel coding block. 2D-MMSE channel estimation. All estimation done within a PRU Short PRBS pilot sequences (sequences with low cross-correlation) are used. Interference profile: [0 0 -3 -4 -5 -7 -9 -12] Direct MMSE is used for demodulation Interference covariance is estimated from 1) pilot tones and null tones for CoFIP 2) pilot tones for Interlaced pilot structure Interference pilot knowledge is NOT used in the 2D-MMSE channel estimation. Additional channel est improvement feasible with using pilot knowledge in CE (approx 1.0 dB gains shown previously) 6

CoFIP outperforms pilot-on-data by over 2.0 dB

Goodput = (1 – bler)*(1- pilot overhead) CoFIP outperforms Pilot-on-Data in goodput

Simulation setup 2 Interference profile at 0 dB SIR [-4.7 -4.7 -4.7dB]. Direct and indirect MMSE are used for demodulation. Thermal noise level is 10 dB below the power of one interferer.

CoFIP outperforms pilot-on-data by over 2.5 dB

Goodput = (1 – bler)*(1- pilot overhead) CoFIP outperforms Pilot-on-Data in goodput

Conclusion CoFIP outperforms pilot-on-data by over 2.0-2.5 dB Knowledge of interference pilot sequence is NOT used in CoFIP receiver With interference pilot knowledge CoFIP which uses pilot-on-pilot collisions benefits Pilot-on-data does not benefit from interferer pilot knowledge The good put of CoFIP is much higher than pilot-on-data CoFIP is suitable for CQI estimation in OL region using always ON pilot in select sub frames Pilot-on-Data does not ensure proper CQI estimation It fails to provide proper CQI if data tones are not transmitted in interfering cells Adopt CoFIP in type-1 OL region

Proposed text ……………………..Start of Text……………………………………………………….  Section 15.3.5.4.1 page 305 line 39 Type-1 OL MIMO region shall use Collision Free Interlaced Pilot (CoFIP) pattern. Figure xxx shows the CoFIP pattern for AAI sub-frames consisting of 6 OFDM symbols. The index of the CoFIP PRU type used by a particular BS with Cell_ID=k is denoted by pk. The index of the pilot pattern set used by a particular BS with the Cell_ID=k is denoted by pk. The index of the pilot pattern set is determined by the Cell_ID according to the following equation: pk = mod(k,3). For AAI sub-frames consisting of 7 OFDM symbols, the first OFDM symbol which contains pilot tones and null tones in each pilot pattern set shown in Figure xxx is added as the 7th symbol Figure yyy shows the pilot pattern set for AAI sub-frames consisting of 5 OFDM symbols

18 contiguous subcarriers 6 symbols 1 X X 1 X 1 18 contiguous subcarriers Pilot pattern set 0 Pilot pattern set 1 Pilot pattern set 2 Figure xxx - The CoFIP Pattern for AAI sub frames with 6 OFDM symbols

18 contiguous subcarriers 5 symbols 1 X X 1 X 1 18 contiguous subcarriers Pilot pattern set 0 Pilot pattern set 1 Pilot pattern set 2 Figure yyy - The CoFIP Pattern for AAI sub frames with 5 OFDM symbols ……………………..End of Text……………………………………………………….