February 2007 Doc IEEE 802 22 07 0000

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 OFDMA Single Channel Harmonization IEEE P 802. 22 Wireless RANs Authors: Date: 2007. 21. 02 Notice: This document has been prepared to assist IEEE 802. 22. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) 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. 22. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http: //standards. ieee. org/guides/bylaws/sb-bylaws. pdf including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard. " Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair Carl R. Stevenson as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802. 22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at patcom@iee. org. > Submission Runcom Technologies Ltd. 1 Eli Sofer, Runcom 1

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 • Adequacy of CAZAC PN sequences • Attributes of PN sequences needed to support WRAN deployment with Reuse factor 1/3 • Partial simulations results on O-PUSC Submission Runcom Technologies Ltd. 2 Eli Sofer, Runcom 2

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Adequacy of proposed CAZAC scheme • the PAPR of preamble is an important property. However, the preamble PAPR should be examined in view of the payload PAPR. That is, decreasing the Preamble PAPR beneath the expected payload PAPR would not lead to any advantage on the system level. • The very low 1 -2 d. B PAPR suggested by the CAZAC approach would give almost no advantage over another series with PAPR in the vicinity of 4 -5 d. B. • Although the CAZAC waveforms are simple to generate (similarity to the sounding waveforms of the 802. 16 e) the decoding/reception complexity is extremely high. This is easy to show by means of comparison with BPSK modulated preamble. The estimation process begin with multiplying the incoming preamble (in the frequency domain) with a series of PN sequences (stored at the UT memory). Obviously, the multiplication of a digital series with a sequence of +1, -1 (BPSK) is far more attractive and simpler than the multiplication with a series of complex value numbers (suggested by CAZAC approach) • Submission Runcom Technologies Ltd. 3 Eli Sofer, Runcom 3

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Adequacy of proposed CAZAC scheme • CAZAC approach would imply a complex HW required to carryout a large number of complex multiplications ( the number is identical to number of pilots within the preamble). The negligible gain of CAZAC preamble on the system level does not justify the massive HW requirements. • we recommend use of binary PN sequences. Submission Runcom Technologies Ltd. 4 Eli Sofer, Runcom 4

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 WRAN deployment with Reuse factor 1/3 (use of aggregated channels) Submission Runcom Technologies Ltd. 5 Eli Sofer, Runcom 5

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Support for Channel aggregation In multi-cell deployment, the popular deployment is with Hexagon like cells. This allows the use of multiple different allocation within the cell (Reuse factor < 1) Reuse 1/3 deployment calls for decimated preamble with factor 3. This means that each segment uses a different set of pilot in Preamble (e. g. every 3 n+k, K= 0, 1, 2). This preamble structure makes sure that the transmitted preamble by all 3 segments remain orthogonal (in the frequency domain) Simulation studies also show that in many scenarios (especially in the low CINR regime) the capacity of a cell with reuse less than 1 (e. g. 1/3) is higher than that in the elementary Reuse 1. We believe that similar deployment ideas will be predicted in the 80 -2. 22 standard. It is therefore important to adhere to the decimation with factor 3 for use as the 802. 22 preambles. Submission Runcom Technologies Ltd. 6 Eli Sofer, Runcom 6

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Preamble Binary PN Sequences • Preamble with 3 repetitions (for three different sectors) • 3 different Binary PN Sequences each shifted by one subcarrier (k= 0, 1, 2), allocated for three different sectors, supports resuse 1/3 (Aggregated channels) • Interference mitigation among sectors, differentiation among sectors 0 3 6 9 12 15 18 21 24 27 30 33 +1 1 4 7 10 13 17 20 23 26 29 32 -1 Sub carriers Submission Runcom Technologies Ltd. 7 Eli Sofer, Runcom 7

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Multicell Deployment with Reuse 1/3 Different PN sequence, each to one of the three sectors Seg • No interference from antenna backlobes on adjacent sectors Seg Submission Runcom Technologies Ltd. • Optimized deployment and better coverage of the sector 8 Eli Sofer, Runcom 8

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 DL structure in Reuse 1/3 • Each one of the three sectors of the cell has a known allocation of the subchannels for FCH. • 4 subchannels (# 0, 1, 2 and 3) extending over two symbols are allocated to FCH 0 (the first sector) • 4 subchannels (#10, 11, 12 and 13) extending over 2 symbols are allocated to FCH 1 • 4 Subchannels (# 20, 21, 22 and 23) extending over 2 symbols are allocated to FCH 2 • Each FCHx (x = 0, 1, 2) is associated with one of the three preambles, therefore the user synchronized to the preamble of a specific sector knows which subchannels are allocated to FCH associated with that sector. • Subcarriers in each Sub-channel (UL and DL) are distributed over the entire frequency band • No impact on OH. Submission Runcom Technologies Ltd. 9 Eli Sofer, Runcom 9

DL structure in Reuse 1/3 February 2007 1 10 11 12 13 … …… …. 20 21 22 23 …… ……. 2 3 4 OFDM Symbols FCH 0 DL Map Preamble 3 reps Sub-Channels 0 1 2 3 … … … Doc. : IEEE 802. 22 -07 -0000 r 3 Major Group 0 UL Map FCH 1 DL Map Major Group 1 UL UL Map FCH 2 DL Map Major Group 2 UL Map Submission Runcom Technologies Ltd. 10 Eli Sofer, Runcom 10

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Multicell deployment with Reuse ½ (4 sectors) • Poor coverage of the sector • Opposite sector in same cell could suffer interference from antenna backlobes. Base Station • Use of only 2 sectors or 4 sectors is not suitable for multicell deployment • Multicell deplyment should use hexagonal cell Submission Runcom Technologies Ltd. 11 Eli Sofer, Runcom 11

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 SINR CDF with Reuse 1/1 Capacity(DL) = 0. 42 bps/Hz Submission Runcom Technologies Ltd. 12 Eli Sofer, Runcom 12

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 SINR CDF with Reuse 1/3 Capacity(DL) = 0. 71 bps/Hz Mobility scenario Submission Runcom Technologies Ltd. 13 Eli Sofer, Runcom 13

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 DL preamble and Ranging process Submission Runcom Technologies Ltd. 14 Eli Sofer, Runcom 14

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Ranging Process • The CDMA like synchronization is achieved by allocating several of the usable Sub-Channels for the Ranging process, the logic unit they consist is called a Ranging Sub-Channel. • Onto the Ranging Sub-Channel users modulate a Pseudo Noise (PN) sequence using BPSK modulation • The Base Station detects the different sequences and uses the CIR that he derives from the sequences for: – Time and power synchronization – Decide on the user modulation and coding Submission Runcom Technologies Ltd. 15 Eli Sofer, Runcom 15

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Effectiveness of DL Preamble and Ranging Example • • • Subscriber Units at the Current OFDMA Symbol = 3 Sub-Channels Allocated to Subscriber-Unit #1 = 12 Sub-Channels Allocated to Subscriber-Unit #2 = 9 Sub-Channels Allocated to Subscriber-Unit #3 = 6 Number Of New Subscriber-Units Requesting Services = 3 All Subscriber-Units Suffer Different Multi-Paths and different Attenuation's Submission Runcom Technologies Ltd. 16 Eli Sofer, Runcom 16

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 • Constellation at the Base Station Submission Runcom Technologies Ltd. 17 Eli Sofer, Runcom 17

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 • Users Separation Submission Runcom Technologies Ltd. 18 Eli Sofer, Runcom 18

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Example - Results • User Estimation 1 Submission Runcom Technologies Ltd. 19 Eli Sofer, Runcom 19

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Results • User Estimation 2 Submission Runcom Technologies Ltd. 20 Eli Sofer, Runcom 20

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Results • User Estimation 3 Submission Runcom Technologies Ltd. 21 Eli Sofer, Runcom 21

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Results • Finding New Subscriber-Units Requesting Services, Using the Ranging Pilots (CDMA/OFDM Techniques) • Synchronization is achieved using DL preamble within accuracy of few micro seconds Amp • Preamble processing gain is 27 d. B, adding to that 9 d. B boosted pilots, overall 36 d. B Time accuracy at UT (o. 1 Microsecond/step) Submission Runcom Technologies Ltd. 22 Eli Sofer, Runcom 22

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Simulations results on O-PUSC (Partial) Submission Runcom Technologies Ltd. 23 Eli Sofer, Runcom 23

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Scope The purpose is to present performance of OPUSC scheme to various types of channel estimation methods. The simulations were ran with OPUSC frame structure for two profiles of WRAN channels. Submission Runcom Technologies Ltd. 24 Eli Sofer, Runcom 24

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Simulations parameters: • • Bandwidth =6 MHz. FFTSize=2048. FEC Size=480; Modulation =QPSK CTC coding. Coding rate=1/2. Guard Interval=256. Submission Runcom Technologies Ltd. 25 Eli Sofer, Runcom 25

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 OPUSC Frame Structure 1 OPUSC Frame Pilot 2048 subcarriers Submission Runcom Technologies Ltd. 26 Eli Sofer, Runcom 26

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Additional assumptions: • The simulation were ran without frequency shift and without phase noise. • Since in the OPUSC scheme the pilots in each symbol are allocated not in all subcarriers, we used linear interpolation to perform channel estimation. Submission Runcom Technologies Ltd. 27 Eli Sofer, Runcom 27

February 2007 Profile 1 Doc. : IEEE 802. 22 -07 -0000 r 3 Channel parameters: Path 1 Path 2 Path 3 Path 4 Path 5 Path 6 Excess delay, msec 0 3 8 11 13 21 Relative amplitude 0 -7 Db -15 Db -22 Db -24 Db -19 Db Doppler frequency 0 0. 1 Hz 2. 5 Hz 0. 13 Hz 0. 17 Hz 0. 37 Hz . Profile 2 Excess delay, msec Path 1 Path 2 Path 3 Path 4 Path 5 Path 6 -3 0 2 4 7 11 Relative amplitude -6 Db 0 -7 Db -22 Db -16 Db -20 Db Doppler frequency 0. 1 Hz 0 0. 13 Hz 2. 5 Hz 0. 17 Hz 0. 37 Hz Submission Runcom Technologies Ltd. 28 Eli Sofer, Runcom 28

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Channel parameters The point spread function(PSD) of each tap is defined as follows: Submission Runcom Technologies Ltd. 29 Eli Sofer, Runcom 29

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Reference Performance: Profile 1 (BER) 10 10 BER 10 10 10 OPUSC allocation QPSK 1/2 FEC 480 Profile 1 0 3 symbols 9 symbols 15 symbols Perfect channel -1 -2 -3 -4 -5 -6 -7 1 2 Submission Runcom Technologies Ltd. 3 4 5 SNR [d. B] 30 6 7 8 9 Eli Sofer, Runcom 30

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Reference Performance: Profile 1 (PER) 10 OPUSC allocation QPSK 1/2 FEC 480 0 3 symbols 9 symbols 15 symbols Perfect channel PER 10 10 -1 -2 -3 -4 1 2 Submission Runcom Technologies Ltd. 3 4 5 SNR [d. B] 31 6 7 8 9 Eli Sofer, Runcom 31

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Reference Performance: Profile 2 (BER) 10 OPUSC allocation QPSK 1/2 FEC 480 Profile 2 0 3 symbols 9 symbols 10 BER 10 10 10 -1 -2 -3 -4 -5 -6 2 Submission Runcom Technologies Ltd. 3 4 5 6 SNR [d. B] 32 7 8 9 10 Eli Sofer, Runcom 32

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Reference Performance: Profile 2 (PER) 10 OPUSC allocation QPSK 1/2 FEC 480 Profile 2 0 3 symbols 9 symbols PER 10 10 -1 -2 -3 -4 2 Submission Runcom Technologies Ltd. 3 4 5 6 SNR [d. B] 33 7 8 9 10 Eli Sofer, Runcom 33

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Conclusions: • The presented graphs show us that we have BER=1 e-5 with SNR=9. 5. In order to improve the channel estimation we suggest to aggregate number of frames (3 and 5). From the first graph we see that the aggregation of 5 frames improves the performance in approx. 3. 5 Db to compare with 1 frame and is close to the perfect channel performance. Submission Runcom Technologies Ltd. 34 Eli Sofer, Runcom 34

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Water filling concept Tiles transmission on preferred frequencies User 1 Tiles spread User 2 SNR Threshold Different thresholds for different modulation schemes and coding rates Channel behavior , different users Submission Runcom Technologies Ltd. 35 Eli Sofer, Runcom 35

February 2007 Doc. : IEEE 802. 22 -07 -0000 r 3 Conclusions • Preamble with 3 reps is recommended (for 3 different segments), accommodating different deployment scenarios and multi-cell scenarios. • Optional PUSC simulation results so far are poor unless used tiles are transmitted in favorable CINR. • The concepts presented by ETRI are almost identical to the transmission scheme (US & DS) of the 802. 16. e. The changes are mostly semantic. We propose to adopt the concepts presented by ETRI (not necessarily the details. Submission Runcom Technologies Ltd. 36 Eli Sofer, Runcom 36