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Content for  TR 45.871  Word version:  14.0.0

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0  IntroductionWord‑p. 5

The rapid globalization of the smart phone market is putting pressure on legacy EDGE networks to improve throughput and spectrum efficiency.
To meet the demands on throughput and spectrum efficiency, MIMO for downlink provides an interesting prospect because it neither puts too high requirements on LTE enabled smart devices nor on legacy EDGE networks. All LTE enabled smart devices come with two receive antennas, which is a valuable radio asset that should be fully utilized. Similarly, legacy EDGE networks are often configured with two transmit antennas to support air combining or transmit diversity.
Performance evaluation submitted to GERAN#54 in GP-120762, to GERAN#55 in GP-121019 and GP-121030 and to GERAN#56 in GP-121248 shows potential of this technique to support significantly higher data peak throughput compared to EGPRS and EGPRS2-A and as well as improving the spectral efficiency.

1  ScopeWord‑p. 6

The present document contains investigations carried out and during the 3GPP study item on MIMO for GSM/EDGE Downlink.
The following items are covered in this study report:
  • Objectives for the study
  • Overview of MIMO for Downlink concept
  • Conceptual design of several functional blocks of this solution
  • Performance evaluations related to envisaged functional blocks belonging to MIMO for Downlink
  • Compatibility analysis

2  References

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
  • References are either specific (identified by date of publication, edition number, version number, etc.) or non specific.
  • For a specific reference, subsequent revisions do not apply.
  • For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
TR 21.905: "Vocabulary for 3GPP Specifications".
GP-130288: "New Study Item on Downlink MIMO", source Nokia Siemens Networks, NOKIA Corporation, Com-Research GmbH, TELECOM ITALIA S.p.A.
TS 45.005: (V7.25.0) "Radio transmission and reception (Release 7)".
TR 45.860: (V11.5.0) "Signal Precoding Enhancements for EGPRS2 DL".
TS 45.002: (V11.0.0) "Multiplexing and multiple access on the radio path".
TS 44.060: (V11.6.0) "General Packet Radio Service (GPRS); Mobile Station (MS) - Base Station System (BSS) interface; Radio Link Control / Medium Access Control (RLC/MAC) protocol".
TS 36.101: (V11.0.0) "Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) radio transmission and reception (Release 11)".
TR 25.814: (V7.1.0) "Physical layer aspects for evolved Universal Terrestrial Radio Access (UTRA) (Release 7)".
TR 25.996: (V10.0.0) "Spatial channel model for Multiple Input Multiple Output (MIMO) simulations (Release 10)".

3  Definitions and abbreviationsWord‑p. 7

3.1  Definitions

For the purposes of the present document, the terms and definitions given in TR 21.905 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905.

3.2  Abbreviations

For the purposes of the present document, the abbreviations given in TR 21.905 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905.)
Blind Modulation Detection
Downlink level A modulation and coding scheme
Mobile Station Receive Diversity
Normal Symbol Rate
Sub Channel Power Imbalance Ratio
Signal to Interference and Noise Ratio

4  Objectives

The objective of the study is to investigate the feasibility of single user MIMO in the downlink for PS data services including EGPRS and EGPRS2-A.
For MIMO support, two operational modes are foreseen:
  1. spatial multiplexing mode based on dual stream 2x2 MIMO; and
  2. single stream diversity mode based on either MSRD or Tx diversity in combination with MSRD.
In general, the study item re-uses as much as possible existing functionality in GERAN and existing spatial channel models and principles used for UTRAN and E-UTRAN. Different aspects of MIMO, as outlined in MIMO study item proposal [2], are studied based on the following performance and compatibility objectives.

4.1  Performance Objectives

The introduction of MIMO for downlink will significantly improve data throughput performance as compared to realistic EGPRS and EGPRS2-A performance. The performance of MIMO will be evaluated over the SINR range relevant in GERAN networks.

4.2  Compatibility Objectives

The impact of MIMO for downlink on GSM speech codecs, GPRS, EGPRS and EGPRS2 will be kept at a minimum. There should be no negative HW impact due to the introduction of MIMO to the base station and mobile station, assuming the mobile station already supports diversity antenna reception.
Any technique that requires changes to MCS design for GSM/EDGE are not part of the study.

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