PHY Structure Design of Nonsynchronized Ranging Sequence for

PHY Structure Design of Non-synchronized Ranging Sequence for IEEE 802. 16 m Document Number: S 80216 m-08/1030 Date Submitted: 2008 -09 -15 Source: Kuhn-Chang Lin and Yu T. Su NCTU/Media. Tek Inc. Yih-Shen Chen, Pei-Kai Liao, I-Kang Fu, and Paul Cheng Media. Tek Inc. E-mail: tony. cm 95 g@nctu. edu. tw, ytsu@mail. nctu. edu. tw E-mail: yihshen. chen@mediatek. com, peikai. liao@mediatek. com, Paul. Cheng@mediatek. com Zheng Yan-Xiu, Richard Li ITRI Venue: IEEE session #57, Kobe Base Contribution: C 80216 m-08/1030 r 1. Purpose: PHY: SDD Session 56 Cleanup; in response to the TGm Call for Contributions and Comments 802. 16 m-08/033 for Session 57 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/sect 6 -7. html#6> and <http: //standards. ieee. org/guides/opman/sect 6. html#6. 3>. Further information is located at <http: //standards. ieee. org/board/pat-material. html> and <http: //standards. ieee. org/board/pat >. 1

Motivation • In the July meeting, the evaluation criteria of non-synchronized ranging channel design was discussed • And, the ranging sequence design and the mapping to subcarriers are TBD 2

Problems on Initial Ranging for 802. 16 e • • • The auto-correlation property would deteriorate when a ranging code is spreading over a large number of OFDM subcarriers Dispersing the ranging subcarriers across the whole band degrades the performance in timing offset estimation, especially for a delay-spread channel To determine the optimal detection threshold, one needs information about Ø Noise power level Ø Multi-user interference • • • Number of RSSs Cross-correlations of the ranging codes Ranging signal strengths 3

Desired Properties for 802. 16 m Initial Ranging Process • No ICI between ranging channels and data channels – Localized ranging channels • Capable of recognizing multiple incoming initial ranging codes without any side information – Non-overlapping subcarriers for ranging code • Excellent Pd, Pf performance, reliable timing offsets, and signal power estimates • The initial ranging codes should be easily generated 4

Ranging Channel • Localized ranging channels 5

Ranging Opportunity • Physical subcarriers are partitioned into Ngp groups, i. e. , ranging opportunity – Partition subcarriers into series of subbands and each subbands consists of Nc subcarriers • The bandwitdh of a subband is smaller than coherent bandwidth – Pick out one subband for every Ngp subbands and compose into logically adjacent subcarrier set; that is, ranging opportunity • The spacing between 2 logically adjacent subbands is larger than coherent bandwidth 6

Frequency Domain Interleaved Polyphase (FDIP) Code • For the i-th RSS choosing the p-th ranging opportunity , in the j-th subband, its FDIP code is represented by where is modification term for PAPR reduction and is cell-specific randomization seed which can be derived from BS ID. 7

Frequency Domain Interleaved Polyphase (FDIP) Code • Properties: – Short code transmitted over multiple sub-band to employ frequency diversity gain – Different Short code sequences are transmitted over non-overlapping subcarriers • More small ROs instead of “collision within a big RO” – ex: One PRBS RO can be partitioned into 4 FDIP ROs 8

Simulation Environments Scenario/ Parameters Values Uplink Bandwidth 10 MHz Frequency spacing 10. 9375 KHz The used number of subcarriers 144 (Nc, Nb, Ngp ) (6, 6, 4) Channel modified ITU Vehicular A Cell size 5 km The speed of each RSS 120 Km/hr Table 1. Simulation parameter values 9

Detection Probability Requirement: 1% mis-detection rate 10

False Alarm Probability Requirement: 0. 1% false alarm probability 11

PAPR Reduction Through Random Phase Rotations 12

Timing Jitter Less than 4 samples, as SNR larger than 4 d. B Fig. 6. Timing jitter behavior as a function of average SNR 13

Normalized MSE of Power Estimate 14

Text Proposal ---------------------------- Start of the Text -------------------11. 9. 2. 4. 2. PHY structure To avoid ICI, the length of the cyclic prefix (CP) must be larger than the RTD. The last part of ranging signal for non-synchronized MSs shall be reserved as guard time (GT) to avoid the inter-symbol interference to next OFDMA symbol due to longer delay of ranging signal. The GT shall be not shorter than RTD. Ranging subcarriers is partitioned into multiple ranging opportunities. The subcarriers for non-synchronized ranging MSs are locally allocated while ranging subcarriers are partitioned into subbabands. One ranging opportunity is composed of several subbands in a distributed manner. ---------------------------- End of the Text -------------------- 15