MIMO midamble proposal IEEE 802 16 Presentation Submission
MIMO midamble proposal IEEE 802. 16 Presentation Submission Template (Rev. 9) Document Number: IEEE S 80216 m-09_0770 Date Submitted: 2009 -04 -27 Source: Alexei Davydov, Apostolos Papathanassiou, Niu Huaning Guangjie Li, Jong-kae Fwu, Yang-seok Choi Intel Corporation Chih-Yuan Lin, Pei-Kai Liao, Paul Cheng Mediatek alexei. davydov@intel. com chihyuan. lin@mediatek. com Venue: IEEE 802. 16 m Session#61, Cairo, Egypt Category: AWD comments / Area: Chapter 15. 3. 5 (DL-PHY) “Comments on AWD 15. 3. 5 (DL-PHY)” Base Contribution: IEEE C 80216 m-09_0770 Purpose: Discussion and approval 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 >.
Introduction • To facilitate downlink and uplink CL MIMO operation reference pilots (MIMO midamble) transmitted without precoding is required • Channel measurements using MIMO midamble can be used – To calculate PMI for DL CL MIMO, – To calculate transmit precoding vector for UL CL MIMO in TDD mode – To calculate CQI values
Proposed Physical Structure of Midamble • First OFDM symbol in DL subframe for midamble transmission (may reside on different DL subframes to support interlace feature) • Frequency decimation to support multiple antenna transmission • Low cross-correlation sequences for modulation of the mid-amble subcarriers to reduce inter-cell interference power via processing gain • Transmission in reuse-1 (flexible design to support other reuse cases if necessary)
Advantages form usage of the single OFDM allocation • Complexity: downlink sub-frames with midamble sequence does not introduce the additional symbol structure and mapping rule – For the type-1 subframe case, the remaining 5 consecutive symbols are formed to be a type-3 subframe. For the type-2 subframe case, the remaining 6 consecutive symbols are formed to be a type-1 subframe. • PAPR advantages – Midamble occupies the entire OFDM symbol (no mixture with data, pilot subcarriers), so a low PAPR sequences and additional power boosting can be used • Flexibility: The midamble structure can support 2, 4 and 8 transmit antenna configuration and different reuses cases in the flexible way • Channel measurements efficiency: the midamble pilots are evenly spaced across the frequency, so the channel estimation performance is improved and filter complexity is reduced
System Level Simulations 4 TX antenna case Perfect channel knowledge w/ midamble estimation Gap against w/o midamble Average sector throughput (Mbps) 17. 20 16. 43 -4. 69% Cell-edge user throughput (Kbps) 588 520 -13. 1% further midamble overhead reduction (by using sparser midamble pattern) may lead to substantial CL performance loss especially for cell edge MS
Impact on the channel estimation efficiency for irregular sub frames • For type-1 subframe and 2 streams pilot pattern the performance degradation due to pilot puncturing is less then 0. 1 d. B (Link Level Analysis (ITU Ped-B 3 kmph), Link Level Analysis (ITU Veh-A 120 kmph)) • For type-1 subframe and 3, 4 streams pilot pattern there is performance advantage due to more dense pilot allocation in time
Link Level Analysis (ITU Ped-B 3 kmph)
Link Level Analysis (ITU Veh-A 120 kmph)
Conclusions • The proposed midamble physical structure offers several advantages and flexibility for 802. 16 m system • Recommendation is to adopt the text provided in IEEE C 80216 m-09/0770 contribution or it’s latest revision
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