Uplink MIMO proposal for IEEE 802.16m Document Number: C80216m-08/538 Date Submitted: 2008-07-06 Source: Yang-seok Choi[1] Alexei Davydov[2] Voice: +1 503 712 1773 [1], +7 831 4162444[2] Alexander Maltsev[2] E-mail: yang-seok.choi@intel.com, alexei.davydov@intel.com, alexander.maltsev@intel.com Intel Corporation [1]Portland, OR, US [2] Russia, Nizhny Novgorod, Ul. Turgeneva, 30 Venue: Call for contributions on project 802.16m SDD: Uplink MIMO Session #56: Denver, USA Base Contribution: IEEE C80216m-08/538 Purpose: For discussion and adoption by IEEE 802.16m group 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 >.

Generic Block Diagram for UL MIMO Precoded Antenna Symbols Data bits QAM Symbols Number of Spatial Channels NSCH Number of Spatial Streams NSS Number of Transmit Antennas NTX Coded bits Space Frequency (Time) Encoded Symbols

Space Frequency Block Codes Rate – 1 Rate – 2 In accordance to IEEE 802.16m system requirement document the system shall support the connection up to the highest supported speed of 350 kmph Space Time Block Code (STBC) is not appropriate for such high speeds due to orthogonally loss in fast channel fading Space-frequency Block Code (SFBC) should be considered as a baseline scheme for IEEE 802.16m due to it’s robustness to the mobility Space Frequency Block Codes offers other advantages: Less buffering requirements – the decoding is performed for single OFMDA symbol Flexible to any frame structure design – easy to satisfy the requirement on even number interval transmissions

SFBC Link Layer Performance Baseline SIMO in Ped.-B (3kmph) STC-A SFBC in Ped.-B (3kmph) STC-A SFBC in Veh.-A (60 kmph) STC-A SFBC in Veh.-A (120 kmph)

SFBC Link Layer Performance (Cont’d) Matrix A rank-1 transmission Matrix B rank-2 transmission

Collaborative MIMO MS 1 MS 1 Base Station MS 1 Base Station Base Station MS 2 MS 2 MS 2 The UL network capacity is limited by the peak data rate of MS due to channel bandwidth, small modulation order and transmit power limitations small number of transmit antennas at the MS due to small form factor of hand held MS devices higher implementation cost of multiple power amplifiers Collaborative MIMO is an effective solution to increase the network capacity in the UL for such scenario collaborative MS may reuse the same time-frequency resource and transmit data simultaneously collaborative MS uses orthogonal pilot allocation to enable MIMO processing at the BS The efficiency of interference mitigation at the BS is provided by proper scheduling of collaborative MS rich direction of arrival distribution of received signal energy at the BS Codebook precoding may be used to improve the efficiency of collaborative MIMO

Collaborative MIMO Link Layer Performance Spatial Multiplexing Further gain of collaborative MIMO over SU-MIMO spatial multiplexing may be achieved by proper MS scheduling and pairing

UL MIMO Codebook Based Precoding MS Base Station The usage of the precoding at the MS is essential to achieve IEEE 802.16m requirements Codebook precoding should be used in conjunction with SU MIMO and Collaborative MIMO Legacy IEEE802.16e codebook is not constant modulus scheme and causes antenna power imbalance problem for power limited MS Low PAPR codebooks constructions is required for IEEE 802.16m UL MIMO Constant amplitude with antenna subset selection codebook (see next slide) Example 1-TX (4 antenna MS) rate-1 antenna selection codebook construction Codebook based precoding procedure MS performs uplink sounding BS determines the precoding vector from channel state information BS signals the precoder index assigned for UL transmission using UL control channel

Constant Amplitude with Antenna Subset Selection Codebook Construction Selection of the TX antenna subset Constant amplitude codebook with antenna subset selection Constant amplitude baseline codebook Antenna selection matrix Precoding on selected antenna subset Advantages of the proposed codebooks Low PAPR Structured construction Easy extensible to any number of MS antennas Optimized to low power MS Limits the actual number of transmitting antenna

Precoding Link Layer Performance

Summary of Proposed Uplink MIMO Modes SU-MIMO Rate 1 Transmit Diversity Space Frequency Block Code (SFBC) Open loop and codebook precoding Rate 2 Spatial Multiplexing Single Codeword (SCW) MU-MIMO Up to four collaborative MS Open loop and precoded collaborative MIMO Two stage codebook precoding based on constant amplitude and antenna subset selection codebooks

Proposed Text for SDD (Cont’d)

Proposed Text for SDD (Cont’d)