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Grid-of-Beams (GoB) Downlink Multi-User MIMO

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Presentation on theme: "Grid-of-Beams (GoB) Downlink Multi-User MIMO"— Presentation transcript:

1 Grid-of-Beams (GoB) Downlink Multi-User MIMO
Document Number: IEEE S802.16m-08/487 Date Submitted: Source: Stephan SAUR, Hardy HALBAUER, {Stephan.Saur, Hardy.Halbauer, Andreas.Rueegg, Andreas RUEEGG, Frank SCHAICH Alcatel-Lucent Venue: Macau, China Base Contribution: IEEE C80216m-08_487.doc Purpose: Discuss and adopt this proposal into the 16m SDD Notice: This document does not represent the agreed views of the IEEE 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 Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: <> and <>. Further information is located at <> and < >.

2 Motivation Several users share one DL radio resource in time and frequency in order to increase the mean cell throughput Multi-user scheduling (user grouping) aims in minimizing the intra-cell interference Application in systems with low frequency reuse factor requires inter-cell interference mitigation in parallel Target: Design of DL MU-System with low complexity that maintains the capability of inter-cell interference coordination Idea: Define a limited set of possible precoding vectors (e.g. 8 vectors) such that vectors build up a Grid-of-Beams (GoB) intra-cell interference is minimal for certain combinations of beams

3 Concept Description … Base Station Mobile Station #n GoB Precoding P
user signal d1 user signal dN Base Station Mobile Station #n SM Detector W user signal dn Channel H feedback of desired beam index

4 Concept Description BS assigns each data stream to one beam (precoding vector) Closed-loop mode: MS reports required beam(s) to BS Open-loop mode: BS derives appropriate beam(s) from UL Certain combinations of beams share one radio resource in time and frequency without severe intra-cell interference (e.g. #2 and #6) Several options for antenna configurations: E.g. linear array of x-pol elements for the transmission of two independent streams to one MS with the same beam index exploiting polarization diversity #8 #7 #6 #5 #4 #3 #2 #1

5 Requirements Closed-loop mode requires “test signal”, e.g. pilots dedicated to each beam (precoding vector) in order to determine that beam, which is received with the highest power level. Closed-loop mode requires feedback channel. Assuming eight possible beams (precoding vectors), three uncoded bits per data stream are necessary.

6 Text Proposal to SDD Start text proposal MIMO modes In 16m, three MIMO modes shall be supported: Single-BS single-user MIMO (SU-MIMO) […] Single-BS multi-user MIMO (MU-MIMO) In downlink, a MU-MIMO scheme based on a limited number of possible precoding vectors building up a grid of beams with spatial separation shall be supported. This scheme aims in increasing the mean cell throughput even in cellular systems with low frequency reuse factor. Main advantage is the capability to support advanced inter-cell interference coordination techniques at the same time. The proposed scheme exhibits very low complexity and can be applied in both closed and open loop MU-MIMO. Either one or two data streams can be assigned to one user. The use of cross-polarized antennas at the base station is recommended. […] Multi-BS MIMO: […] End text proposal

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