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Cooperative MIMO with Randomized Distributed Spatial Multiplexing

IEEE 802.16 Presentation Submission Template (Rev. 8.3) Document Number:

IEEE S80216m-Date Submitted:

2008-10-30Source: Chun Nie, Pei Liu, Shu Luo, Thanasis Korakis, Shivendra Panwar Voice: 718-260-3740 Polytechnic Institute of New York University, Fax: 718-260-3074 (formerly Polytechnic University) Email: cnie01@students.poly.edu; 6 Metrotech , Brooklyn, NY 11201 pliu@poly.edu

shuo01@students.poly.edu korakis@poly.edu;

panwar@catt.poly.eduVenue: IEEE 802.16 Session #58, Denver, Dallas (relay)Base Document:

IEEE C802.16m-Purpose:

To incorporate cooperative MIMO with randomized distributed spatial multiplexing proposed herein into IEEE 802.16m system description document (SDD).Notice:

This document has been prepared to assist IEEE 802.16. 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.

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23/04/18 IEEE S802.16m-2

Cooperative MIMO with Randomized Distributed Spatial Multiplexing

Chun Nie, Pei Liu, Shu Luo, Thanasis Korakis, Shivendra PanwarPolytechnic Institute of New York University, Brooklyn, NY,

11201(formerly Polytechnic University, NY)

Authors:

Outline

Introduction Randomized Distributed Spatial Multiplexing (RDSM) Summary of RDSM Advantages Performance Evaluation Conclusions

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Introduction (1/2)

In this contribution, we propose the use of Randomized Distributed Spatial Multiplexing (RDSM) to boost the uplink capacity in a two-hop virtual MIMO system

RDSM is a SM technique that uses Relay Stations (RSs) and Subscriber Stations (SSs) as “helpers” to deliver higher data rtes.

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Introduction (2/2)

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RDSM is implemented in a 2-hop system for the uplink transmission– First hop: All potential helpers decode the source signal. – Second hop: Helpers cooperatively forward the signal to destination by using

RDSM encoded signals.

Spatial multiplexing gain is achieved over the second-hop. RDSM encoder is embedded in each helper as follows.

RDSM does not limit the number of antenna elements at each helper.

MIMO encoder’s output: K parallel streams, where K is no larger than the minimum of (M, L), assuming BS has L antennas and the second hop has M helpers.

Each helper transmits a random weighted sum of all K streams.

,

Summary of RDSM Advantages Provides spatial multiplexing gain for the second hop of a single-antenna SS in

the uplink When the number of stations is large, the source can recruit enough helpers to

transmit at peak rate. Better than Distributed BLAST

– A predetermined number of helpers in the system is NOT needed. – No need to index each helper and assign a specific antenna for each of them. Thus,

signaling is reduced. All potential helpers can contribute to cooperation.– SS are allowed to participate in cooperation and transparently cooperate with RS to

enhance spatial multiplexing gain. – Detailed channel information over the two hops is NOT necessary. The transmitter

only needs a statistical estimation of the channel to estimate the outage performance. Hence, signaling for channel estimation is minimized.

– RDSM is easy to implement in each helper station by using embedded software. No substantial increment in hardware complexity

Conclusion:

RDSM is more robust than Distributed BLAST

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Performance Evaluation

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Setting:• V-BLAST is used for comparison. • Each helper is single-antenna; BS has 4 antennas• Single-hop: Direct transmission• Two-Hop Single-Relay: One RS only• RDSM

0 20 40 60 80 10015

20

25

30

35

40

45

50

55Network aggregrated throughput

Number of SS

Th

rou

gh

pu

t (b

it/s)

Single-hopTwo hop, 1-helperRDSM

10 15 20 25 30 35 40

10-4

10-3

10-2

10-1

SNR (db)

BE

R

QPSK

Randomized Spatial MultiplexingCentralized BLAST

Conclusions

RDSM can significantly enhance system performance in terms of throughput.

RDSM significantly increases performance for SS at the cell edge. RDSM provides BER performance comparable to a centralized

spatial multiplexing system (e.g., BLAST) RDSM is more robust than a general distributed BLAST system. RDSM can be incorporated in a multi-hop scenario. We suggest incorporating RDSM into IEEE 802.16m

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