Mobile terminal apparatus, radio base station apparatus, radio communication method and radio communication system

Patent metadata

Field	Value
Publication number	US-9351177-B2
Application number	US-201214110738-A
Country	US
Kind code	B2
Filing date	Apr 12, 2012
Priority date	Apr 15, 2011
Publication date	May 24, 2016
Grant date	May 24, 2016

Abstract

The present invention is designed to provide a mobile terminal apparatus, a radio base station apparatus and a radio communication method which, even when a MIMO technique and a CoMP technique are applied together, can optimize the effects of both techniques. The mobile terminal apparatus estimates downlink channel states using reference signals included in downlink signals from a plurality of cells, determines the PMI for each cell and inter-cell phase difference information, from the channel states of the plurality of cells, such that the combinations of the PMI of each cell and inter-cell phase difference information become optimal, measures channel quality from the determined PMIs and inter-cell phase difference information, and transmits the PMI for each cell, the inter-cell phase difference information and channel quality information, to a radio base station apparatus.

First claim

The invention claimed is:

1. A mobile terminal apparatus with a processor comprising:
an estimation section that estimates channel states of a plurality of cells using reference signals included in downlink signals from the plurality of cells;
a determining section that determines a PMI (Precoding Matrix Indicator) of each cell and inter-cell phase difference information, from the channel states of the plurality of cells;
a measurement section that measures channel quality from the PMIs and inter-cell phase difference information determined in the determining section; and
a transmission section that transmits the PMI of each cell, the inter-cell phase difference information and information about the channel quality, to a radio base station apparatus,
wherein the determining section determines the PMI of a serving cell from a channel state of the serving cell, and determines the combinations of the PMIs of other cells than the serving cell and the inter-cell phase difference information from the channel states of the plurality of cells and the PMI of the serving cell, such that throughput or received SINR (Signal to Interference and Noise Ratio) is maximized; and
wherein the determining section determines the PMI of the serving cell using the following equation 10, and determines the PMIs of the other cells and the inter-cell phase difference information using the following equations 11:

[

Formula
⁢

⁢
1

]

P
^

1

=

arg
⁢

⁢
max

1
≤

j
1

≤

2
N

⁢



H
1

·

P

j
1



2

(

Equation
⁢

⁢
10

)

where
j: a codebook index of the PMI
N: a codebook size of the PMI (bits)
H 1 : the channel state of the serving cell
P j1 : a codeword index in the serving cell

⁢

[

Formula
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⁢
2

]

{

P
^

2

,
…
⁢

,

P
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K

,

W
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,
…
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,

W
^

K

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=

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max

1
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i
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i
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Assignees

• Nagata Satoshi
• Yun Xiang
• She Xiaoming
• Chen Lan
• Ntt Docomo Inc

Inventors

• Nagata Satoshi
• Yun Xiang
• She Xiaoming
• Chen Lan

Classifications

• H04W72/541

  using the level of interference · CPC title

• H04B7/0456

  Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting · CPC title

• H04W24/02 Primary

  Arrangements for optimising operational condition · CPC title

• H04B7/0639

  Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection · CPC title

• H04B7/024 Primary

  Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems · CPC title