U.S. patent application number 16/342373 was filed with the patent office on 2020-02-20 for base station apparatus, terminal apparatus, and communication method.
This patent application is currently assigned to Sharp Kabushiki Kaisha. The applicant listed for this patent is FG INNOVATION COMPANY LIMITED, SHARP KABUSHIKI KAISHA. Invention is credited to Hiromichi TOMEBA, Ryota YAMADA.
Application Number | 20200059337 16/342373 |
Document ID | / |
Family ID | 62076885 |
Filed Date | 2020-02-20 |
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United States Patent
Application |
20200059337 |
Kind Code |
A1 |
YAMADA; Ryota ; et
al. |
February 20, 2020 |
BASE STATION APPARATUS, TERMINAL APPARATUS, AND COMMUNICATION
METHOD
Abstract
A base station apparatus includes a downlink reference signal
generation unit configured to generate a first demodulation
reference signal and a second demodulation reference signal that
are reference signals used to demodulate a data signal, and a radio
transmitting unit configured to transmit the first demodulation
reference signal, the second demodulation reference signal, and
control information to the terminal apparatus. The control
information includes parameters regarding the first demodulation
reference signal and parameters regarding the second demodulation
reference signal. The parameters regarding the first demodulation
reference signal include an antenna port number. The parameters
regarding the second demodulation reference signal include an
antenna port number, and a time domain density or a frequency
domain density with which demodulation reference signals are mapped
into a slot. The first demodulation reference signal is mapped
before the second demodulation reference signal in the slot.
Inventors: |
YAMADA; Ryota; (Sakai City,
JP) ; TOMEBA; Hiromichi; (Sakai City, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHARP KABUSHIKI KAISHA
FG INNOVATION COMPANY LIMITED |
Sakai City, Osaka
Tuen Mun, New Territories, Hong Kong |
|
JP
CN |
|
|
Assignee: |
Sharp Kabushiki Kaisha
Sakai City, Osaka
JP
FG Innovation Company Limited
Tuen Mun, New Territories, Hong Kong
CN
|
Family ID: |
62076885 |
Appl. No.: |
16/342373 |
Filed: |
November 2, 2017 |
PCT Filed: |
November 2, 2017 |
PCT NO: |
PCT/JP2017/039720 |
371 Date: |
April 16, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 88/08 20130101;
H04L 5/001 20130101; H04W 88/02 20130101; H04L 5/0051 20130101;
H04L 27/26 20130101; H04W 72/042 20130101; H04L 5/0023 20130101;
H04L 27/2613 20130101; H04W 72/0446 20130101; H04L 5/0091
20130101 |
International
Class: |
H04L 5/00 20060101
H04L005/00; H04W 72/04 20060101 H04W072/04; H04L 27/26 20060101
H04L027/26 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 2, 2016 |
JP |
2016-214930 |
Claims
1. A base station apparatus for communicating with a terminal
apparatus, the base station apparatus comprising: a downlink
reference signal generation unit configured to generate a first
demodulation reference signal and a second demodulation reference
signal that are reference signals used to demodulate a data signal;
and a radio transmitting unit configured to transmit the first
demodulation reference signal, the second demodulation reference
signal, and control information to the terminal apparatus, wherein
the control information includes parameters regarding the first
demodulation reference signal and parameters regarding the second
demodulation reference signal, the parameters regarding the first
demodulation reference signal include an antenna port number, the
parameters regarding the second demodulation reference signal
include an antenna port number, and a time domain density or a
frequency domain density with which demodulation reference signals
are mapped into a slot, and the first demodulation reference signal
is mapped before the second demodulation reference signal in the
slot.
2. The base station apparatus according to claim 1, wherein a
spatial multiplexing order supported for the first demodulation
reference signal is lower than a spatial multiplexing order
supported for the second demodulation reference signal.
3. The base station apparatus according to claim 1, wherein the
first demodulation reference signal is mapped in a fixed mapping
pattern for each carrier frequency range.
4. The base station apparatus according to claim 3, wherein the
first demodulation reference signal is mapped to all subcarriers of
the slot in one of the carrier frequency ranges.
5. The base station apparatus according to claim 1, wherein the
frequency domain density for the first demodulation reference
signal is higher than the frequency domain density for the second
demodulation reference signal, and the time-domain density for the
first demodulation reference signal is lower than the time domain
density for the second demodulation reference signal.
6. A terminal apparatus for communicating with a base station
apparatus, the terminal apparatus comprising: a radio receiving
unit configured to receive, from the base station apparatus, a
first demodulation reference signal and a second demodulation
reference signal that are reference signals used to demodulate a
data signal, the data signal, and control information; and a signal
detection unit configured to demodulate the data signal by using
the first demodulation reference signal and the second demodulation
reference signal, wherein the control information includes
parameters regarding the first demodulation reference signal and
parameters regarding the second demodulation reference signal, the
parameters regarding the first demodulation reference signal
include an antenna port number, the parameters regarding the second
demodulation reference signal include an antenna port number, and a
time domain density or a frequency domain density with which
demodulation reference signals are mapped into a slot, and the
first demodulation reference signal is mapped before the second
demodulation reference signal in the slot.
7. The terminal apparatus according to claim 6, wherein a spatial
multiplexing order supported for the first demodulation reference
signal is lower than a spatial multiplexing order supported for the
second demodulation reference signal.
8. The terminal apparatus according to claim 6, wherein the first
demodulation reference signal is mapped in a fixed mapping pattern
for each carrier frequency range.
9. The terminal apparatus according to claim 8, wherein the first
demodulation reference signal is mapped to all subcarriers of the
slot in one of the carrier frequency ranges.
10. The terminal apparatus according to claim 6, wherein the
frequency domain density for the first demodulation reference
signal is higher than the frequency domain density for the second
demodulation reference signal, and the time domain density for the
first demodulation reference signal is lower than the time domain
density for the second demodulation reference signal.
11. A communication method in a base station apparatus for
communicating with a terminal apparatus, the communication method
comprising: a downlink reference signal generation step of
generating a first demodulation reference signal and a second
demodulation reference signal that are reference signals used to
demodulate a data signal; and a radio transmission step of
transmitting the first demodulation reference signal, the second
demodulation reference signal, and control information to the
terminal apparatus, wherein the control information includes
parameters regarding the first demodulation reference signal and
parameters regarding the second demodulation reference signal, the
parameters regarding the first demodulation reference signal
include an antenna port number, the parameters regarding the second
demodulation reference signal include an antenna port number, and a
time domain density or a frequency domain density with which
demodulation reference signals are mapped into a slot, and the
first demodulation reference signal is mapped before the second
demodulation reference signal in the slot.
12. A communication method in a terminal apparatus for
communicating with a base station apparatus, the communication
method comprising: a radio receiving step of receiving, from the
base station apparatus, a first demodulation reference signal and a
second demodulation reference signal that are reference signals
used to demodulate a data signal, the data signal, and control
information; and a signal detection step of demodulating the data
signal by using the first demodulation reference signal and the
second demodulation reference signal, wherein the control
information includes parameters regarding the first demodulation
reference signal and parameters regarding the second demodulation
reference signal, the parameters regarding the first demodulation
reference signal include an antenna port number, the parameters
regarding the second demodulation reference signal include an
antenna port number, and a time domain density or a frequency
domain density with which demodulation reference signals are mapped
into a slot, and the first demodulation reference signal is mapped
before the second demodulation reference signal in the slot.
Description
TECHNICAL FIELD
[0001] The present invention relates to a base station apparatus, a
terminal apparatus, and a communication method.
[0002] This application claims priority based on JP 2016-214930
filed on Nov. 2, 2016, the contents of which are incorporated
herein by reference.
BACKGROUND ART
[0003] In a communication system such as Long Term Evolution (LTE)
or LTE-Advanced (LTE-A) standardized by the Third Generation
Partnership Project (3GPP), the communication area can be widened
by forming a cellular configuration in which multiple areas,
covered by base station apparatuses (base stations, transmission
stations, transmission points, downlink transmission devices,
uplink reception devices, a group of transmit antennas, a group of
transmit antenna ports, component carriers, eNodeB, Access Point,
and AP) or transmission stations equivalent to the base station
apparatuses, are deployed in the form of multiple cells (Cells). A
terminal apparatus (reception station, reception point, downlink
reception apparatus, uplink transmission apparatus, receive antenna
group, receive antenna port group, UE, station, and STA) is
connected to the base station. In such a cellular configuration,
frequency efficiency can be improved by using the same frequency
among neighboring cells or sectors.
[0004] Research and development activities related to the 5th
generation mobile radio communication system (5G system) have been
actively carried out, aiming to start commercial services around
the year 2020. A vision recommendation on the standard system of
the 5G system (International mobile telecommunication--2020 and
beyond: IMT-2020) was recently reported (see NPL 1) by the
International Telecommunication Union Radio Communications Sector
(ITU-R), which is an international standardization body.
[0005] The 5G system assumes that a radio access network is
operated by combining various frequency bands to satisfy various
requirements represented by three large use scenarios (Enhanced
mobile broadband (EMBB), Enhanced Massive machine type
communication (eMTC), and Ultra-reliable and low latency
communication (URLLC)). Thus, unlike the known LTE/LTE-A, it is
assumed that the 5G system uses multiple frame formats with
different radio parameters (subcarrier spacings and the like)
although the 5G system has the same access scheme as LTE/LTE-A.
CITATION LIST
Non Patent Literature
[0006] NPL 1: "IMT Vision--Framework and overall objectives of the
future development of IMT for 2020 and beyond", Recommendation
ITU-R M. 2083-0, September 2015.
SUMMARY OF INVENTION
Technical Problem
[0007] However, it is assumed that the multiple frame formats
involve respective suitable communication schemes and communication
methods. The 5G system needs to be a system for integrating the
frame formats together, with communications suitable for the
respective frame formats maintained.
[0008] In view of these circumstances, an object of the present
invention is to provide a base station apparatus, a terminal
apparatus, and a communication method that are capable of improving
communication performance such as throughput and communication
efficiency in a system using multiple frame formats.
Solution to Problem
[0009] To address the above-mentioned drawbacks, a base station
apparatus, a terminal apparatus, and a communication method
according to an aspect of the present invention are configured as
follows.
[0010] According to an aspect of the present invention, a base
station apparatus for communicating with a terminal apparatus is
provided, the base station apparatus including a downlink reference
signal generation unit configured to generate a first demodulation
reference signal and a second demodulation reference signal that
are reference signals used to demodulate a data signal, and a radio
transmitting unit configured to transmit the first demodulation
reference signal, the second demodulation reference signal, and
control information to the terminal apparatus, wherein the control
information includes parameters regarding the first demodulation
reference signal and parameters regarding the second demodulation
reference signal, the parameters regarding the first demodulation
reference signal include an antenna port number, the parameters
regarding the second demodulation reference signal include an
antenna port number, and a time domain density or a frequency
domain density with which demodulation reference signals are mapped
into a slot, and the first demodulation reference signal is mapped
before the second demodulation reference signal in a slot.
[0011] Furthermore, in the base station apparatus according to an
aspect of the present invention, a spatial multiplexing order
supported for the first demodulation reference signal is lower than
a spatial multiplexing order supported for the second demodulation
reference signal.
[0012] Furthermore, in the base station apparatus according to an
aspect of the present invention, the first demodulation reference
signal is mapped in a fixed mapping pattern for each carrier
frequency range.
[0013] Furthermore, in the base station apparatus according to an
aspect of the present invention, the first demodulation reference
signal is mapped to all subcarriers of the slot in one of the
carrier frequency ranges.
[0014] Furthermore, in the base station apparatus according to an
aspect of the present invention, the frequency domain density for
the first demodulation reference signal is higher than the
frequency domain density for the second demodulation reference
signal, and the time domain density for the first demodulation
reference signal is lower than the time domain density for the
second demodulation reference signal.
[0015] According to an aspect of the present invention, a terminal
apparatus for communicating with a base station apparatus is
provided, the terminal apparatus including a radio receiving unit
configured to receive, from the base station apparatus, a first
demodulation reference signal and a second demodulation reference
signal that are reference signals used to demodulate a data signal,
the data signal, and control information, and a signal detection
unit configured to demodulate the data signal by using the first
demodulation reference signal and the second demodulation reference
signal, wherein the control information include parameters
regarding the first demodulation reference signal and parameters
regarding the second demodulation reference signal, the parameters
regarding the first demodulation reference signal include an
antenna port number, the parameters regarding the second
demodulation reference signal include an antenna port number, and a
time domain density or a frequency domain density with which
demodulation reference signals are mapped into a slot, and the
first demodulation reference signal is mapped before the second
demodulation reference signal in a slot.
[0016] Furthermore, in the terminal apparatus according to an
aspect of the present invention, a spatial multiplexing order
supported for the first demodulation reference signal is lower than
a spatial multiplexing order supported for the second demodulation
reference signal.
[0017] Furthermore, in the terminal apparatus according to an
aspect of the present invention, the first demodulation reference
signal is mapped in a fixed mapping pattern for each carrier
frequency range.
[0018] Furthermore, in the terminal apparatus according to an
aspect of the present invention, the first demodulation reference
signal is mapped to all subcarriers of the slot in one of the
carrier frequency ranges.
[0019] Furthermore, in the terminal apparatus according to an
aspect of the present invention, the frequency domain density for
the first demodulation reference signal is higher than the
frequency domain density for the second demodulation reference
signal, and the time domain density for the first demodulation
reference signal is lower than the time domain density for the
second demodulation reference signal.
[0020] According to an aspect of the present invention, a
communication method in a base station apparatus for communicating
with a terminal apparatus is provided, the communication method
including a downlink reference signal generation step of generating
a first demodulation reference signal and a second demodulation
reference signal that are reference signals used to demodulate a
data signal, and a radio transmission step of transmitting the
first demodulation reference signal, the second demodulation
reference signal, and control information to the terminal
apparatus, wherein the control information includes parameters
regarding the first demodulation reference signal and parameters
regarding the second demodulation reference signal, the parameters
regarding the first demodulation reference signal include an
antenna port number, the parameters regarding the second
demodulation reference signal include an antenna port number, and a
time domain density or a frequency domain density with which
demodulation reference signals are mapped into a slot, and the
first demodulation reference signal is mapped before the second
demodulation reference signal in the slot.
[0021] According to an aspect of the present invention, a
communication method in a terminal apparatus for communicating with
a base station apparatus is provided, the communication method
including a radio receiving step of receiving, from the base
station apparatus, a first demodulation reference signal and a
second demodulation reference signal that are reference signals
used to demodulate a data signal, the data signal, and control
information, and a signal detection step of demodulating the data
signal by using the first demodulation reference signal and the
second demodulation reference signal, wherein the control
information includes parameters regarding the first demodulation
reference signal and parameters regarding the second demodulation
reference signal, the parameters regarding the first demodulation
reference signal include an antenna port number, the parameters
regarding the second demodulation reference signal include an
antenna port number, and a time domain density or a frequency
domain density with which demodulation reference signals are mapped
into a slot, and the first demodulation reference signal is mapped
before the second demodulation reference signal in the slot.
Advantageous Effects of Invention
[0022] According to an aspect of the present invention,
communication performance can be improved in a system using
multiple frame formats.
BRIEF DESCRIPTION OF DRAWINGS
[0023] FIG. 1 is a diagram illustrating an example of a
communication system according to the present embodiment.
[0024] FIG. 2 is a diagram illustrating an example of a frame
structure according to the present embodiment.
[0025] FIG. 3 is a diagram illustrating an example of the frame
structure according to the present embodiment.
[0026] FIG. 4 is a diagram illustrating an example of the frame
structure according to the present embodiment.
[0027] FIG. 5 is a diagram illustrating an example of the frame
structure according to the present embodiment.
[0028] FIG. 6 is a diagram illustrating an example of the frame
structure according to the present embodiment.
[0029] FIG. 7 is a diagram illustrating an example of mapping of
demodulation reference signals according to the present
embodiment.
[0030] FIG. 8 is a diagram illustrating an example of the mapping
of demodulation reference signals according to the present
embodiment.
[0031] FIG. 9 is a diagram illustrating an example of the mapping
of demodulation reference signals according to the present
embodiment.
[0032] FIG. 10 is a diagram illustrating an example of the mapping
of demodulation reference signals according to the present
embodiment.
[0033] FIG. 11 is a block diagram illustrating an example
configuration of a base station apparatus according to the present
embodiment.
[0034] FIG. 12 is a block diagram illustrating an example
configuration of a terminal apparatus according to the present
embodiment.
DESCRIPTION OF EMBODIMENTS
[0035] A communication system according to the present embodiment
includes a base station apparatus (a transmitter, cells, a
transmission point, a group of transmit antennas, a group of
transmit antenna ports, component carriers, and eNodeB) and
terminal apparatuses (a terminal, a mobile terminal, a reception
point, a reception terminal, a receiver, a group of receive
antennas, a group of receive antenna ports, and UE). Furthermore, a
base station apparatus connected to a terminal apparatus (base
station apparatus that establishes a radio link with a terminal
apparatus) is referred to as a serving cell.
[0036] The base station apparatus and the terminal apparatus in the
present embodiment can communicate in a licensed band and/or an
unlicensed band.
[0037] According to the present embodiment, "X/Y" includes the
meaning of "X or Y". According to the present embodiment, "X/Y"
includes the meaning of "X and Y". According to the present
embodiment, "X/Y" includes the meaning of "X and/or Y".
[0038] FIG. 1 is a diagram illustrating an example of a
communication system according to the present embodiment. As
illustrated in FIG. 1, the communication system according to the
present embodiment includes a base station apparatus 1A and
terminal apparatuses 2A and 2B. Coverage 1-1 is a range (a
communication area) in which the base station apparatus 1A can
connect to the terminal apparatuses. The terminal apparatuses 2A
and 2B are also collectively referred to as terminal apparatuses
2.
[0039] With respect to FIG. 1, the following uplink physical
channels are used for uplink radio communication from the terminal
apparatus 2A to the base station apparatus 1A. The uplink physical
channels are used for transmitting information output from a higher
layer. [0040] Physical Uplink Control Channel (PUCCH) [0041]
Physical Uplink Shared Channel (PUSCH) [0042] Physical Random
Access Channel (PRACH)
[0043] The PUCCH is used to transmit Uplink Control Information
(UCI). The Uplink Control Information includes a positive
ACKnowledgement (ACK) or a Negative ACKnowledgement (NACK)
(ACK/NACK) for downlink data (a downlink transport block or a
Downlink-Shared CHannel (DL-SCH)). ACK/NACK for the downlink data
is also referred to as HARQ-ACK or HARQ feedback.
[0044] Here, the Uplink Control Information includes Channel State
Information (CSI) for the downlink. The Uplink Control Information
includes a Scheduling Request (SR) used to request an Uplink-Shared
CHannel (UL-SCH) resource. The Channel State Information refers to
a Rank Indicator (RI) for specifying a suited spatial multiplexing
number, a Precoding Matrix Indicator (PMI) for specifying a suited
precoder, a Channel Quality Indicator (CQI) for specifying a suited
transmission rate, a CSI-Reference Signal (RS) Resource Indication
(CRI) for specifying a suited CSI-RS resource, and the like.
[0045] The Channel Quality Indicator (hereinafter, referred to as a
CQI value) can be a suited modulation scheme (e.g., QPSK, 16QAM,
64QAM, 256QAM, or the like) and a suited coding rate in a
prescribed band (details of which will be described later). The CQI
value can be an index (CQI Index) determined by the above change
scheme, coding rate, and the like. The CQI value can take a value
predetermined in the system.
[0046] Note that the Rank Indicator and the Precoding Quality
Indicator can take the values predetermined in the system. The Rank
Indicator and the Precoding Matrix Indicator can be an index
determined by the number of spatial multiplexing and Precoding
Matrix information. Note that values of the Rank Indicator, the
Precoding Matrix Indicator, and the Channel Quality Indicator are
collectively referred to as CSI values.
[0047] PUSCH is used for transmission of uplink data (an uplink
transport block, UL-SCH). Furthermore, PUSCH may be used for
transmission of ACK/NACK and/or Channel State Information along
with the uplink data. In addition, PUSCH may be used to transmit
the uplink control information only.
[0048] PUSCH is used to transmit an RRC message. The RRC message is
a signal/information that is processed in a Radio Resource Control
(RRC) layer. Further, PUSCH is used to transmit an MAC Control
Element (CE). Here, MAC CE is a signal/information that is
processed (transmitted) in a Medium Access Control (MAC) layer.
[0049] For example, a power headroom may be included in MAC CE and
may be reported via PUSCH. In other words, a MAC CE field may be
used to indicate a level of the power headroom.
[0050] PRACH is used to transmit a random access preamble.
[0051] In the uplink radio communication, an UpLink Reference
Signal (UL RS) is used as an uplink physical signal. The uplink
physical signal is not used for transmission of information output
from higher layers, but is used by the physical layer. The Uplink
Reference Signal includes a DeModulation Reference Signal (DMRS)
and a Sounding Reference Signal (SRS).
[0052] DMRS is associated with transmission of PUSCH or PUCCH. For
example, the base station apparatus 1A uses DMRS in order to
perform channel compensation of PUSCH or PUCCH. SRS is not
associated with the transmission of PUSCH or PUCCH. For example,
the base station apparatus 1A uses SRS to measure an uplink channel
state.
[0053] In FIG. 1, the following downlink physical channels are used
for the downlink radio communication from the base station
apparatus 1A to the terminal apparatus 2A. The downlink physical
channels are used for transmitting information output from the
higher layer. [0054] Physical Broadcast CHannel (PBCH) [0055]
Physical Control Format Indicator CHannel (PCFICH) [0056] Physical
Hybrid automatic repeat request Indicator CHannel (PHICH) [0057]
Physical Downlink Control CHannel (PDCCH) [0058] Enhanced Physical
Downlink Control CHannel (EPDCCH) [0059] Physical Downlink Shared
CHannel (PDSCH)
[0060] PBCH is used for broadcasting a Master Information Block
(MIB, a Broadcast CHannel (BCH)) that is shared by the terminal
apparatuses. PCFICH is used for transmission of information for
indicating a region (e.g., the number of Orthogonal Frequency
Division Multiplexing (OFDM) symbols) to be used for transmission
of PDCCH.
[0061] PHICH is used for transmission of ACK/NACK with respect to
uplink data (a transport block, a codeword) received by the base
station apparatus 1A. In other words, PHICH is used for
transmission of a HARQ indicator (HARQ feedback) for indicating
ACK/NACK with respect to the uplink data. Note that ACK/NACK is
also called HARQ-ACK. The terminal apparatus 2A reports ACK/NACK
having been received to a higher layer. ACK/NACK refers to ACK for
indicating a successful reception, NACK for indicating an
unsuccessful reception, and DTX for indicating that no
corresponding data is present. In a case that PHICH for uplink data
is not present, the terminal apparatus 2A reports ACK to a higher
layer.
[0062] The PDCCH and the EPDCCH are used to transmit downlink
control information (DCI). Here, multiple DCI formats are defined
for transmission of the downlink control information. In other
words, a field for the downlink control information is defined in a
DCI format and is mapped to information bits.
[0063] For example, as a DCI format for the downlink, DCI format 1A
to be used for the scheduling of one PDSCH in one cell
(transmission of a single downlink transport block) is defined.
[0064] For example, the DCI format for the downlink includes
downlink control information such as information of PDSCH resource
allocation, information of a Modulation and Coding Scheme (MCS) for
PDSCH, and a TPC command for PUCCH.
[0065] Here, the DCI format for the downlink is also referred to as
downlink grant (or downlink assignment).
[0066] Furthermore, for example, as a DCI format for the uplink,
DCI format 0 to be used for the scheduling of one PUSCH in one cell
(transmission of a single uplink transport block) is defined.
[0067] For example, the DCI format for the uplink includes uplink
control information such as information of PUSCH resource
allocation, information of MCS for PUSCH, and a TPC command for
PUSCH. Here, the DCI format for the uplink is also referred to as
uplink grant (or uplink assignment).
[0068] Furthermore, the DCI format for the uplink can be used to
request Channel State Information (CSI; also referred to as
reception quality information) for the downlink (CSI request).
[0069] The DCI format for the uplink can be used for a
configuration for indicating an uplink resource to which a CSI
feedback report is mapped, the CSI feedback report being fed back
to the base station apparatus by the terminal apparatus. For
example, the CSI feedback report can be used for a configuration
for indicating an uplink resource that periodically reports Channel
State Information (periodic CSI). The CSI feedback report can be
used for a mode configuration (CSI report mode) for periodically
reporting the Channel State Information.
[0070] For example, the CSI feedback report can be used for a
configuration for indicating an uplink resource that reports
aperiodic Channel State Information (aperiodic CSI). The CSI
feedback report can be used for a mode configuration (CSI report
mode) for aperiodically reporting the Channel State Information.
The base station apparatus can configure any one of the periodic
CSI feedback report and the aperiodic CSI feedback report. In
addition, the base station apparatus can configure both the
periodic CSI feedback report and the aperiodic CSI feedback
report.
[0071] The DCI format for the uplink can be used for a
configuration for indicating a type of the CSI feedback report that
is fed back to the base station apparatus by the terminal
apparatus. The type of the CSI feedback report includes wideband
CSI (e.g., Wideband CQI), narrowband CSI (e.g., Subband CQI), and
the like.
[0072] In a case where a PDSCH resource is scheduled in accordance
with the downlink assignment, the terminal apparatus receives
downlink data on the scheduled PDSCH. In a case where a PUSCH
resource is scheduled in accordance with the uplink grant, the
terminal apparatus transmits uplink data and/or uplink control
information on the scheduled PUSCH.
[0073] PDSCH is used to transmit downlink data (a downlink
transport block, DL-SCH). PDSCH is used to transmit a system
information block type 1 message. The system information block type
1 message is cell-specific information.
[0074] The PDSCH is used to transmit a system information message.
The system information message includes a system information block
X other than the system information block type 1. The system
information message is cell-specific information.
[0075] PDSCH is used to transmit an RRC message. Here, the RRC
message transmitted from the base station apparatus may be shared
by multiple terminal apparatuses in a cell. Further, the RRC
message transmitted from the base station apparatus 1A may be a
dedicated message to a given terminal apparatus 2 (also referred to
as dedicated signaling). In other words, user equipment specific
information (unique to user equipment) is transmitted by using a
message dedicated to the given terminal apparatus. PDSCH is used to
transmit MAC CE.
[0076] Here, the RRC message and/or MAC CE is also referred to as
higher layer signaling.
[0077] PDSCH can be used to request downlink channel state
information. PDSCH can be used for transmission of an uplink
resource to which a CSI feedback report is mapped, the CSI feedback
report being fed back to the base station apparatus by the terminal
apparatus. For example, the CSI feedback report can be used for a
configuration for indicating an uplink resource that periodically
reports Channel State Information (periodic CSI). The CSI feedback
report can be used for a mode configuration (CSI report mode) for
periodically reporting the Channel State Information.
[0078] The type of the downlink Channel State Information report
includes wideband CSI (e.g., Wideband CSI) and narrowband CSI
(e.g., Subband CSI). The wideband CSI calculates one piece of
Channel State Information for the system band of a cell. The
narrowband CSI divides the system band in predetermined units, and
calculates one piece of Channel State Information for each
division.
[0079] In the downlink radio communication, a Synchronization
signal (SS) and a DownLink Reference Signal (DL RS) are used as
downlink physical signals. The downlink physical signals are not
used for transmission of information output from the higher layers,
but are used by the physical layer.
[0080] The synchronization signal is used for the terminal
apparatus to take synchronization in the frequency domain and the
time domain in the downlink. The Downlink Reference Signal is used
for the terminal apparatus to perform channel compensation on a
downlink physical channel. For example, the Downlink Reference
Signal is used for the terminal apparatus to calculate the downlink
Channel State Information.
[0081] Here, the Downlink Reference Signals include a Cell-specific
Reference Signal (CRS), a UE-specific Reference Signal (URS)
relating to PDSCH, a DeModulation Reference Signal (DMRS) relating
to EPDCCH, a Non-Zero Power Chanel State Information--Reference
Signal (NZP CSI-RS), and a Zero Power Chanel State
Information--Reference Signal (ZP CSI-RS).
[0082] CRS is transmitted in an entire band of a subframe and is
used to perform demodulation of PBCH/PDCCH/PHICH/PCFICH/PDSCH. URS
relating to PDSCH is transmitted in a subframe and a band that are
used for transmission of PDSCH to which URS relates, and is used to
demodulate PDSCH to which URS relates.
[0083] DMRS relating to EPDCCH is transmitted in a subframe and a
band that are used for transmission of EPDCCH to which DMRS
relates. DMRS is used to demodulate EPDCCH to which DMRS
relates.
[0084] A resource for NZP CSI-RS is configured by the base station
apparatus 1A. The terminal apparatus 2A performs signal measurement
(channel measurement) by using NZP CSI-RS. A resource for ZP CSI-RS
is configured by the base station apparatus 1A. With zero output,
the base station apparatus 1A transmits ZP CSI-RS. The terminal
apparatus 2A performs interference measurement in a resource to
which NZP CSI-RS corresponds, for example.
[0085] A Multimedia Broadcast multicast service Single Frequency
Network (MBSFN) RS is transmitted in an entire band of the subframe
used for transmitting PMCH. MBSFN RS is used to demodulate PMCH.
PMCH is transmitted through the antenna port used for transmission
of MBSFN RS.
[0086] Here, the downlink physical channel and the downlink
physical signal are also collectively referred to as a downlink
signal. The uplink physical channel and the uplink physical signal
are also collectively referred to as an uplink signal. The downlink
physical channel and the uplink physical channel are collectively
referred to as a physical channel. The downlink physical signal and
the uplink physical signal are also collectively referred to as a
physical signal.
[0087] BCH, UL-SCH, and DL-SCH are transport channels. Channels
used in the Medium Access Control (MAC) layer are referred to as
transport channels. A unit of the transport channel used in the MAC
layer is also referred to as a Transport Block (TB) or a MAC
Protocol Data Unit (PDU). The transport block is a unit of data
that the MAC layer delivers to the physical layer. In the physical
layer, the transport block is mapped to a codeword, and coding
processing or the like is performed for each codeword.
[0088] Furthermore, for terminal apparatuses that support Carrier
Aggregation (CA), the base station apparatus can integrate multiple
Component Carriers (CCs) for transmission in a broader band to
perform communication. In carrier aggregation, one Primary Cell
(PCell) and one or more Secondary Cells (SCells) are configured as
a set of serving cells.
[0089] Furthermore, in Dual Connectivity (DC), a Master Cell Group
(MCG) and a Secondary Cell Group (SCG) are configured as a group of
serving cells. MCG includes a PCell and optionally one or more
SCells. Furthermore, SCG includes a primary SCell (PSCell) and
optionally one or more SCells.
[0090] The base station apparatus can communicate by using a radio
frame. The radio frame includes multiple subframes (sub-periods).
In a case that a frame length is expressed in time, for example, a
radio frame length can be 10 milliseconds (ms), and a subframe
length can be 1 ms. In this example, the radio frame includes 10
subframes. Furthermore, the subframe includes multiple OFDM
symbols, thus the subframe length can be expressed in the number of
OFDM symbols. For example, the subframe can be expressed in the
number of OFDM symbols at a reference subcarrier spacing (for
example, 15 kHz). For example, the number of OFDM symbols for
indicating the subframe length can be 14. Furthermore, the subframe
includes multiple slots. The slot is expressed in the number of
OFDM symbols at a subcarrier spacing used for transmission. The
number of OFDM symbols of the slot may be associated with the
number of OFDM symbols of the subframe. For example, the number of
OFDM symbols of the slot can be the same as or half of the number
of OFDM symbols of the subframe. For example, the slot includes 7
or 14 OFDM symbols. Furthermore, the number of OFDM symbols
constituting the slot may vary according to the subcarrier spacing.
For example, in a case of a subcarrier spacing of 60 kHz or higher,
the slot includes 14 OFDM symbols. In the description below, the
subframe length, in a case of being expressed in time, is 1 ms.
However, the aspect of the present invention is not limited to
this. Furthermore, the subframe/slot can include an uplink period
during which an uplink signal/channel is communicated and a
downlink period during which a downlink signal/channel is
communicated. In other words, the subframe/slot may include only an
uplink period, only a downlink period, or an uplink period and a
downlink period. Furthermore, the subframe/slot can include a guard
period (null period). Note that a position at which the guard
period can be allocated and/or a guard period length may be fixed
or configured by the base station apparatus. Furthermore, a
configurable period length may vary depending on whether the guard
period is allocated before or after the subframe/slot. Furthermore,
the period lengths may be fixed for a subframe/slot including an
uplink period, a downlink period, and a guard period, depending on
the allocation of the periods. Furthermore, the base station
apparatus can configure, in a higher layer, the allocation and the
period lengths of the uplink period/downlink period/guard period in
the subframe/slot, and transmit, to the terminal, the allocation
and the period lengths included in control information.
Furthermore, the base station apparatus can be configured for each
subframe/slot or each subframe group. Furthermore, a minislot
shorter than the slot may be defined. The subframe/slot/minislot
can be used as a scheduling unit. For example, in a case that the
slot is 14 OFDM symbols, the minislot may be 2, 4, or 7 OFDM
symbols. Furthermore, for example, in a case that the slot is 7
OFDM symbols, the minislot is 4 or 7 OFDM symbols.
[0091] The subframe/slot includes one or more OFDM symbols. In the
embodiments below, it is assumed that the OFDM symbol refers to a
symbol generated based on Inverse Fast Fourier Transform (IFFT),
and that the OFDM signal refers to a OFDM symbol to which a guard
period is added. Note that the guard period is a zero period (null
period) or Cyclic Prefix (CP). Note that the guard period length
may be zero.
[0092] Multiple parameters may be configured to generate OFDM
symbols. The parameters include a subcarrier spacing and/or the
number of Fast Fourier Transform (FFT) points. Furthermore, a base
parameter is configured that is a basis for multiple parameters.
Note that the base parameter is also referred to as a reference
parameter. The parameters other than the base parameter can be
determined based on the base parameter. For example, in a case that
the base parameter is a subcarrier spacing of 15 kHz, the
parameters other than the base parameter can each be N-times the
subcarrier spacing of 15 kHz. Note that N is an integer or the m-th
power of 2 or a fraction. Note that m is an integer and includes a
negative number such as m=-2. Note that the N or m is referred to
as a scale factor for the subcarrier spacing (parameter set).
Furthermore, a parameter, such as a subcarrier spacing, that has a
fixed value is referred to as a parameter set. In the embodiments
described below, by way of example, a first parameter set is a
subcarrier spacing of 15 kHz and a second parameter set is a
subcarrier spacing of 30 kHz, unless otherwise noted. However, the
aspect of the present invention is not limited to this.
Furthermore, the number of parameter sets that can be configured by
the base station apparatus is not limited to two. In the
embodiments described below, the number of FFT points is the same
between the first parameter set and the second parameter set,
unless otherwise noted. In other words, the OFDM symbol length
decreases as the subcarrier spacing increases. Furthermore, OFDM
symbols generated by the first parameter set and the second
parameter set are respectively referred to as first OFDM symbols
and second OFDM symbols.
[0093] Furthermore, for a reduction in the adverse effect of phase
noise or the like, the subcarrier spacing is desirably increased as
the carrier frequency (band) becomes higher. Accordingly, the base
station apparatus can configure a base parameter set by using a
carrier frequency (band) or a carrier frequency range (band range).
For example, a first frequency range (band range) covers carrier
frequencies lower than 6 GHz, a second frequency range (band range)
covers carrier frequencies higher than or equal to 6 GHz and lower
than 40 GHz, and a third frequency range (band range) covers
carrier frequencies higher than or equal to 40 GHz. In this case,
the base station apparatus can configure the base parameter to be a
subcarrier spacing of 15 kHz within the first carrier frequency
range. The base station apparatus can also configure the base
parameter to be a subcarrier spacing of 60 kHz within the second
carrier frequency range. The base station apparatus can also
configure the base parameter to be a subcarrier spacing of 240 kHz
within the third carrier frequency range.
[0094] Furthermore, multiple types of CP lengths may be configured.
Multiple types of CP lengths may also be configured for each
parameter set. For example, two types of CP lengths are configured.
Furthermore, the two types of CPs are respectively referred to as a
first CP and a second CP. For the same parameter set, the second CP
length is longer than the first CP length. Furthermore, the radio
(overhead) of the first CP length and the second CP length to OFDM
symbols can be almost the same for each parameter set. Note that
the first CP is also referred to as a normal CP and the second CP
is also referred to as an extended CP. Furthermore, an OFDM signal
in which the first CP is added to the first OFDM symbol is referred
to as a first OFDM signal-1, and an OFDM signal in which the second
CP is added to the first OFDM symbol is referred to as a first OFDM
signal-2. Furthermore, an OFDM signal in which the first CP is
added to the second OFDM symbol is referred to as a second OFDM
signal-1, and an OFDM signal in which the second CP is added to the
second OFDM symbol is referred to as a second OFDM signal-2. Note
that multiple CP lengths may not be configured in some parameter
sets. Furthermore, the number of CP lengths configured may vary for
each parameter set. Note that multiple CP lengths may be configured
in a special parameter set. Note that, in the embodiments described
above or below, OFDM symbols/signals are used even for description
of the uplink (corresponding to a case where the terminal apparatus
performs transmission) but that the OFDM symbols/signals include
the meanings of OFDM symbols/signals and SC-FDMA symbols/signals
unless otherwise noted. Furthermore, the parameter set and the CP
length can each have the same configuration or different
configurations for the downlink and the uplink. The terminal
apparatus can demodulate downlink signals (OFDM signals) by using
the parameter set and the CP length configured for the downlink and
transmit uplink signals (OFDM signals and SC-FDMA signals) by using
the parameter set and the CP length configured for the uplink. Note
that the reference parameter may be common to the uplink and the
downlink. In this case, the subframe lengths determined from the
reference parameter are equal between the uplink and the
downlink.
[0095] Note that the number of subframes/slots included in a
prescribed time period can have the same value or different values
between the uplink and the downlink. For example, the number of
subframes/slots included in the prescribed time period in the
downlink can be smaller than the number of subframes/slots included
in the prescribed time period in the uplink and vice versa. The
base station apparatus and the terminal apparatus included in the
above-described communication system can provide a communication
service with different requirements configured for the uplink and
the downlink. The communication service is, for example, a
communication service in which high-speed transmission such as
video transmission is performed in the downlink, and low delay
response to the video transmission is required in the uplink. In
other words, a case is included where the subframe/slot length in
the uplink needs to be configured to be smaller than the
subframe/slot length in the downlink. Again, the present embodiment
includes a case where the subframe/slot length in the downlink
needs to be configured to be smaller than the subframe/slot length
in the uplink.
[0096] Note that, in a case that part of the resources in the
uplink or the downlink are used for transmission in another link
(for example, a sidelink), the terminal apparatus can use, for the
transmission in the sidelink, a parameter set and a CP length that
are different from the parameter set and the CP length configured
for the uplink transmission (or downlink transmission) using the
part of the resources, or the parameter set and the CP length can
be configured by the base station apparatus. Of course, the
terminal apparatus can use, for the transmission in the sidelink,
the same parameter set and CP length as those configured for the
uplink transmission (or downlink transmission) using the part of
the resources. Furthermore, a dedicated parameter set and a CP
length for the sidelink can be configured in the terminal
apparatus.
[0097] In the present embodiment, sizes in the time domain such as
the frame length, symbol length, and CP length are expressed in
basic time units Ts. Note that points represent the number of
certain basic time units Ts unless otherwise noted. For example, in
a case that CP is expressed in NCP points, the CP length is the
product of NCP and Ts. Here, the basic time unit Ts can be
determined from a subcarrier spacing and an FFT size (the number of
FFT points). Here, in a case that the subcarrier spacing is
represented as SCS and the number of FFT points is represented as
NFFT, Ts=1/(SCS.times.NFFT) seconds (here, / means a division).
Accordingly, in a case that the subcarrier spacing is multiplied by
N with the number of FFT points remaining the same, the CP length
is divided by N. Note that Ts may be, for example, a time unit
based on reference parameters (subcarrier spacing and the number of
FFT points) such as SCS=15 kHz and NFFT=2048 points. In this case,
the basic time unit is Ts/N (here, / means a division) in a case
that the subcarrier spacing is 15N kHz. Furthermore, in a case that
NFFT is multiplied by N with SCS remaining the same, the basic time
unit is Ts/N (here, / means a division).
[0098] Furthermore, with a common NFFT, the number of CP points can
be common to all parameters except for some OFDM symbols. For
example, the first CP can have 144 points and the second CP can
have 512 points for the OFDM symbols other than the first symbol of
0.5 ms. Furthermore, with the same NFFT, the system bandwidth
varies according to SCS. Note that such a system bandwidth
determined by SCS is also referred to as a reference system
bandwidth. For example, the reference system bandwidth can be 20
MHz in a case of SCS=15 kHz and 80 MHz in a case of SCS=60 kHz. In
a case that the system bandwidth is the same for each SCS, NFFT is
different for each SCS, Ts is kept the same by SCS, and the number
of CP points varies according to SCS. Note that not all the
parameter sets may follow a unified rule based on a variation in
SCS, for example, multiplication by N. In other words, the
overheads of the first CP/second CP may not be equal for all the
parameter sets. For example, in a case that N is a fraction, the
overhead of CP can be reduced. Furthermore, in a case that N is 4
or larger or the like, leading a large reference system bandwidth,
the overhead of CP can be reduced. Note that a CP of which overhead
is less than the first CP is referred to as a Shortened CP (SCP).
Furthermore, the shortened CP is also referred to as a third CP.
Note that the third CP may include a case of NCP=0. Note that a
third CP having a zero length is also referred to as a zero CP.
Furthermore, a signal in which the third CP is added to OFDM
symbols is referred to as an OFDM signal-3. Note that the OFDM
signal-3 may not be time-multiplexed with the OFDM signal-1 and the
OFDM signal-2. Furthermore, the OFDM signal-3 may not be
time-multiplexed/frequency-multiplexed with the OFDM signal-1 and
the OFDM signal-2. Furthermore, in a case of adding the third CP,
the base station apparatus can configure a CP length specific to
the terminal apparatus (guard period length, zero period length, or
null period length). In this case, the base station apparatus can
transmit the third CP on a control channel commonly used within the
cell and transmit the CP length specific to the terminal on a
control channel specific to the terminal. Furthermore, the third CP
may be configured only within a certain carrier frequency
range.
[0099] In general, delay spread is similar at equivalent carrier
frequencies regardless of the subcarrier spacing, thus the CP
length desirably has a value at which the delay spread causes less
adverse effect. Accordingly, the base station apparatus can
configure a base (reference) CP length for each parameter set at
the carrier frequency or within the carrier frequency range. For
example, within the first carrier frequency range, the first CP can
be the base CP for the first parameter set and the second CP can be
the base CP for the second parameter set. Note that the delay
spread is affected by coverage (transmit power) of the base station
apparatus, a cell radius, a distance between the base station
apparatus and the terminal apparatus, and the like, thus, at the
same carrier frequency, varying the CP length for each base station
apparatus/each terminal apparatus enables efficient communication.
Accordingly, in the same subframe, the base station
apparatus/terminal apparatus can multiplex, in the time
domain/frequency domain, the OFDM symbols to which the first CP is
added and the OFDM symbols to which the second CP is added. The
base station apparatus/terminal apparatus can then transmit the
resultant OFDM symbols. The OFDM symbols to which the first CP is
added and the OFDM symbols to which the second CP is added may be
the same parameter set or different parameter sets. Furthermore, in
a case that the subframe is configured to be the number of OFDM
symbols corresponding to the reference parameter (subcarrier
spacing), the number of OFDM symbols may be determined with the
first CP or the second CP taken into account. Furthermore, the
first CP or the second CP, or the CP length may be included in the
reference parameters.
[0100] Note that the parameter set supported by the terminal
apparatus is reported to the base station apparatus as a function
(capability) or a category of the terminal apparatus. Furthermore,
information for indicating whether the first CP/second CP/third CP
is supported at a certain subcarrier spacing can be included in the
function (capability) or the category of the terminal apparatus.
The information for indicating whether the first CP/second CP/third
CP is supported can be indicated for each band or for each band
combination. The base station apparatus can transmit a transmit
signal with the parameter set or the CP length supported by the
terminal apparatus, based on the function (capability) or the
category of the terminal apparatus received from the terminal
apparatus.
[0101] FIGS. 2 to 6 illustrate examples of subframe structures.
FIG. 2 is a diagram illustrating an example of a subframe including
first OFDM signals-1. FIG. 3 is a diagram illustrating an example
of a subframe including second OFDM signals-1. The first parameter
set is a subcarrier spacing of 15 kHz and the second parameter set
is a subcarrier spacing of 30 kHz, thus, the length of the second
OFDM signal-1 is half the length of the first OFDM signal-1.
Accordingly, in a case that 14 first OFDM signals-1 are included in
1 ms, 28 second OFDM signals-1 are included in 1 ms. FIG. 4 is a
diagram illustrating an example of a subframe including second OFDM
signals-2. Propagation environments, such as multipath delay, at
the same carrier frequency (band) are considered to be equivalent
regardless of the parameters. Accordingly, the required CP length
is desirably determined for each carrier frequency (band). In this
case, the base station apparatus transmits OFDM signals with a CP
length suitable for each carrier frequency (band). At this time,
the terminal apparatus performs reception processing with a CP
length determined for the carrier frequency (band) or a configured
CP length.
[0102] Furthermore, FIG. 5 illustrates an example in which the
first OFDM signal-1 and the second OFDM signal-1 are multiplexed in
1 ms. The length of the second OFDM signal-1 is half the length of
the first OFDM signal-1, thus two second OFDM signals-1 are
included in the period of the first OFDM signal-1. Accordingly, the
base station apparatus can select whether to map the first OFDM
signal-1 or two second OFDM signals-1 for each period of the first
OFDM signal-1. In the example in FIG. 5, two second OFDM signals-1
are mapped in the second period of the first OFDM signal-1. Note
that the CP length may vary slightly for each OFDM signal. For
example, in Long Term Evolution (LTE), the subcarrier spacing is
1.5 kHz, thus seven first OFDM signals-1 are included in a slot
(0.5 ms). In the seven first OFDM signals-1, the CP length added to
the first OFDM signal differs from the CP length added to the
remaining OFDM signals. In a case that, the subcarrier spacing,
which is a parameter similar to that in LTE, is 30 kHz, the CP
length added to the first and eighth second OFDM signals-1 of the
14 second OFDM signals-1 included in 0.5 ms differs from the CP
length added to the remaining second OFDM signals-1. In this case,
the period of the first OFDM signal-1 including two second OFDM
signals is limited. Thus, in a case of a subcarrier spacing of 30
kHz, the CP length added to the first second OFDM signal-1 of the
14 second OFDM signals-1 included in 0.5 ms is configured to differ
from the CP length added to the remaining second OFDM signals-1.
This configuration allows each of the seven periods of the first
OFDM signal-1 to include two second OFDM signals-1 (two second OFDM
signals-1 are evenly included in each of the seven periods of the
first OFDM signal-1), thus improving flexibility. In a case that
the second parameter subcarrier spacing is larger than 15 kHz (for
example, N-fold) with the same CP overhead, the CP length added to
the first OFDM symbol in 0.5 ms is adjusted to make the length of N
OFDM signals equal to the length of one 15-kHz OFDM signal. Note
that, in a case that the subcarrier spacing is smaller than 15 kHz
(for example, one Nth), the CP length is adjusted to make the
length of one OFDM signal equal to the length of two 15-kHz OFDM
signals.
[0103] The terminal apparatus uses a synchronization
signal/discovery signal for time/frequency synchronization to
perform a cell search for detecting a physical cell identity (PCID,
cell ID, or system ID) and/or a beam search for detecting a beam
identifier (beam ID or beam cell ID). Note that the cell ID can
include a beam ID. Furthermore, a cell ID including a beam ID is
also referred to as an extended cell ID to distinguish between the
cell ID including a beam ID and a cell ID including no beam ID.
Furthermore, the discovery signal includes some or all of a
synchronization signal, a cell-specific reference signal, and
CSI-RS. In a case that a synchronization signal is generated based
on a cell ID and a beam ID, the terminal apparatus can recognize
the cell ID and the beam ID from a synchronization signal sequence.
Furthermore, in a case that the base station apparatus changes a
beam pattern based on a radio resource such as a subframe to which
the synchronization signal is mapped, the synchronization signal is
generated based on information about the cell ID and the radio
resources. Examples of the information about the radio resources
include a subframe number and a subband number.
[0104] Furthermore, one or more types of synchronization signals
may be used. In a case that two types of synchronization signals,
which are a Primary Synchronization Signal (PSS) and a Secondary
Synchronization Signal (SSS), are used, the cell ID and/or the beam
ID need to be recognized by using both PSS and SSS. Furthermore,
different types of synchronization signal may be responsible for
respective functions. For example, PSS can be used to identify the
cell ID, and SSS can be used to identify the beam ID. In another
example, PSS and SSS can be used to identify the cell ID, and
another synchronization signal can be used to identify the beam
ID.
[0105] In a case of supporting data communication with the first
parameter set and the second parameter set at the same carrier
frequency (band), the base station apparatus can transmit the
synchronization signal/discovery signal with the first parameter
and/or the second parameter. In other words, the base station
apparatus can transmit the synchronization signal/discovery signal
with the parameter specified for each carrier frequency/band. In
this case, the terminal apparatus receives the synchronization
signal/discovery signal with the parameter specified for each
carrier frequency/band to perform a cell search. Furthermore, the
base station apparatus can transmit the synchronization
signal/discovery signal with multiple parameters at a certain
carrier frequency/band. In this case, the terminal apparatus
receives the synchronization signal/discovery signal with the
multiple parameters to perform a cell search. Alternatively, for
example, in a case that the parameter is specified for each
service, the terminal apparatus receives a synchronization
signal/discovery signal with the desired parameter to perform a
cell search.
[0106] The base station apparatus can configure a common signal
period for a certain subframe. A common signal period length can be
configured by using the number of OFDM symbols or the time period.
During the common signal period, some or all of a cell-specific
reference signal, a CSI-RS, and a synchronization signal are
transmitted. In a case of the same common signal period length, the
number of symbols included in the common signal period varies
depending on the parameter set. For example, in a case of a common
signal period length including two first OFDM signals-1, the same
common signal period length includes four second OFDM signals-1.
Accordingly, transmission of the synchronization signal during the
common signal period improves synchronization accuracy because the
second OFDM signal-1 can transmit more synchronization signals than
the first OFDM signal-1. Alternatively, in terms of a cell search,
the second OFDM signal-1 can transmit the synchronization signal
more repeatedly compared to the first OFDM signal-1, thus allowing
the coverage to be extended with the synchronization accuracy
maintained. Note that the common signal period may have a fixed
length.
[0107] Furthermore, in a case that the base station apparatus
transmits the synchronization signal/discovery signal with a
specified parameter (for example, the first parameter set) at a
certain carrier frequency and transmits a data signal with another
parameter set (for example, the second parameter set), the data
signal can be transmitted by using the first parameter set, and the
synchronization signal/discovery signal can be transmitted by using
the second parameter set. In this case, the terminal apparatus uses
the synchronization signal/discovery signal with the second
parameter set to synchronize with the base station apparatus and
uses the first parameter set to demodulate the data signal. FIG. 6
is a diagram illustrating an example of a subframe structure in a
case that the data signal is transmitted by using the second
parameter set and that the synchronization signal is transmitted by
using the first parameter set. In the example in FIG. 6, the common
signal period, which is a signal period common within the cell, is
configured in 1 ms (within the subframe). A signal transmitted
during the common signal period may be the same signal sequence
within the cell or a different sequence for each terminal
apparatus. Furthermore, the common signal period length may be
fixed or configured by the base station apparatus. Note that
different parameters can be used for the primary synchronization
signal and the secondary synchronization signal. For example, the
base station apparatus can transmit the primary synchronization
signal by using a common parameter in a cell (in the example of
FIG. 6, the first parameter set) and transmit the secondary
synchronization signal by using the same parameter (in the example
of FIG. 6, the second parameter set) as that for the data signal.
Note that a synchronization signal with the common parameter in the
cell is also referred to as a cell specific synchronization signal
and a synchronization signal with a parameter specific to a
terminal is also referred to as a UE specific synchronization
signal. Furthermore, the common signal period needs to be
configured in a subframe in which the synchronization signal is
transmitted. For example, in a case that the synchronization signal
is transmitted at an interval of 5 ms (or five subframes), the
common signal period is configured at an interval of 5 ms (or five
subframes). Note that the discovery signal can include the cell
specific synchronization signal. Note that a transmission period of
the synchronization signal may be configured by the base station
apparatus. The transmission period of the synchronization signal
can be included in the system information. Note that a common
parameter set in a cell used for the synchronization signal and the
like can be the same as a reference parameter set and a reference
CP. In this case, the base station apparatus does not need to
transmit a parameter set for the synchronization signal, thus
enabling a reduction in overhead. Furthermore, the common parameter
set in the cell may differ from the reference parameter set and the
reference CP. This enhances flexibility of the system to allow the
base station apparatus/terminal apparatus to configure parameters
suitable for various use cases or scenarios.
[0108] Furthermore, the base station apparatus can
frequency-multiplex multiple parameter sets. For example, in a
certain subframe, the base station apparatus can use the first
parameter set in one subband of the system bandwidth and use the
second parameter set in another subband. In other words, signals
with different subcarrier spacings are multiplexed in the system
bandwidth. In a case that power spectral density is constant in the
system bandwidth, signal power per subcarrier of the first
parameter set is lower than signal power per subcarrier of the
second parameter set. In other words, in a case that the number of
subcarriers allocated is the same between a transmit signal with
the first parameter set and a transmit signal with the second
parameter set, the transmit power of the first parameter set is
lower than the transmit power of the second parameter set. In this
case, the terminal apparatus can determine receive power of the
second parameter set based on receive power of the first parameter
set for demodulation. Note that, in order for different parameter
sets to have similar synchronization accuracy, the transmit power
of the first parameter set is desirably made equivalent to the
transmit power of the second parameter set, for the synchronization
signal. For example, in the same system bandwidth, the number of
subcarriers of the synchronization signal with the first parameter
set is double the number of subcarriers of the synchronization
signal with the second parameter set. Alternatively, the
synchronization signal with the first parameter set has the same
number of subcarriers as the synchronization signal with the second
parameter set, and the synchronization signal with the first
parameter set has the same signal power per subcarrier as the
synchronization signal with the second parameter set. Furthermore,
in a case that the base station apparatus transmits a reference
signal common to the first parameter set and the second parameter
set, the terminal apparatus can recognize transmit power of a data
signal/reference signal with a different parameter, the transmit
power being specific to the different parameter set, based on the
transmit power of the reference signal.
[0109] Furthermore, the subframe structure may vary depending on
whether the cell is an anchor cell such as a macro cell or the
like. For example, the base station apparatus can transmit, in
PCell, a subframe in which the common signal period is configured
but may not necessarily transmit, in SCell, a subframe in which the
common signal period is configured. In other words, PCell and SCell
have different configurations regarding the common signal period,
and the base station apparatus can configure no common signal
period in SCell. Furthermore, the base station apparatus can vary
the number of parameter sets for each cell in the same band. For
example, the base station apparatus can transmit a signal with one
parameter set in PCell and a signal with multiple parameter sets in
SCell. Furthermore, the base station apparatus can use a common
parameter set for each CC to perform transmission. In this case,
the terminal apparatus uses a parameter set configured for PCell to
perform communication in SCell.
[0110] Furthermore, the base station apparatus can recognize
suitable CSI based on a CSI report from the terminal apparatus. The
CSI reported by the terminal apparatus includes CQI/PMI/RI/CRI/PSI.
Parameter Set Indication (PSI) is an indicator for indicating a
suitable one of multiple parameter sets. CSI is calculated from the
cell specific reference signal or CSI-RS. Note that, for the
CSI-RS, a CSI-RS that is not beamformed (non-precoded CSI-RS) or a
CSI-RS that is beamformed (beamformed CSI-RS) can be transmitted
(configured). Furthermore, the base station apparatus can include
the information of the non-precoded CSI-RS or the information of
the beamformed CSI-RS in configuration information about CSI-RS.
The information about the non-precoded CSI-RS includes some or all
of information about CodeBook Subset Restriction (CBSR),
information about a code book, and interference measurement
restriction that is a configuration of whether to restrict
resources in measurement of interference. The information about the
beamformed CSI-RS includes some or all of an ID list of CSI-RS
configurations, an ID list of CSI-Interference Measurement (CSI-IM)
configurations, information about codebook subset restriction, and
interference measurement restriction that is a configuration of
whether to restrict resources in measurement of interference. The
ID list of CSI-IM configurations includes ID information about one
or more CSI-IM configurations, and the ID information about CSI-IM
configurations includes some or all of CSI-IM configuration IDs and
the interference measurement restriction. Furthermore, CSI-IM is
used for interference measurement.
[0111] The base station apparatus can associate at least CSI-RS for
channel measurement with CSI-IM for interference measurement to
include, in the higher layer signalling, a configuration (CSI
process) regarding a procedure for calculating channel state
information. The CSI process can include some or all of the CSI
process ID, the information of the non-precoded CSI-RS, and the
information of the beamformed CSI-RS. The base station apparatus
can configure one or more CSI processes. The base station apparatus
can generate feedback of CSI independently for each of the CSI
processes. The base station apparatus can configure a different
CSI-RS resource and different CSI-IM for each CSI process. The
terminal apparatus performs a CSI report individually for each of
one or more CSI processes configured. Furthermore, the CSI process
is configured in a prescribed transmission mode.
[0112] For example, inter-carrier interference occurs during
high-speed movement, thus a subcarrier spacing during the
high-speed movement is desirably wider than that during low-speed
movement. Thus, the base station apparatus can transmit a CSI-RS
configuration for the CSI report for each parameter set. In this
case, the terminal apparatus can calculate CSI for each parameter
set to report the CSI to the base station apparatus. Furthermore,
the base station apparatus can include the configurations of the
parameter sets in one CSI-RS configuration. In this case, the
terminal apparatus selects a suitable parameter set from the
configured multiple parameter sets to report PSI. Note that the
base station apparatus can map, in the common signal period, a
CSI-RS with a parameter set different from a parameter set for data
transmission. Furthermore, the terminal apparatus can transmit, to
the base station apparatus, a scheduling request or a communication
request with a parameter set different from a parameter set for
data transmission. In this case, the base station apparatus
transmits a CSI-RS with a different parameter set in accordance
with the request from the terminal apparatus.
[0113] As described above, the base station apparatus may transmit
a signal with multiple parameter sets at a certain carrier
frequency. In a case that a neighbor cell also supports multiple
parameter sets, the terminal apparatus may receive a signal with a
different parameter set as neighbor cell interference. To reduce
the neighbor cell interference, the terminal apparatus can
eliminate or suppress the neighbor cell interference. In a case
that the terminal apparatus includes a function to eliminate or
suppress the neighbor cell interference, the base station apparatus
can transmit assist information (neighbor cell information) for
eliminating or suppressing the neighbor cell interference. The
assist information includes some or all of a physical cell ID, the
number of CRS ports, a P.sub.A list, P.sub.B, a Multimedia
Broadcast multicast service Single Frequency Network (MBSFN)
subframe configuration, a transmission mode list, a resource
allocation granularity, a subframe structure, a ZP/NZP CSI-RS
configuration, Quasi Co-Location (QCL) information, a frame format,
parameter sets supported, parameter sets configured for the
respective subframes, the CP length, the FFT size, the system
bandwidth, and whether the system is LTE. P.sub.A is a power ratio
(power offset) of PDSCH and CRS in an OFDM symbol to which CRS is
not mapped. P.sub.B is a power ratio (power offset) of PDSCH in an
OFDM symbol to which CRS is mapped and PDSCH in an OFDM symbol to
which CRS is not mapped. The subframe structure is information for
indicating whether the subframe is the uplink subframe, the
downlink subframe, or the uplink and downlink subframe. The QCL
information is information about QCL for a prescribed antenna port,
a prescribed signal, or a prescribed channel. In a case that long
term performance of a channel on which a symbol on an antenna port
is carried can be estimated from a channel on which a symbol on
another antenna port is carried, the two antenna ports are said to
be quasi co-located (have a relationship of QCL). The long term
performance includes delay spread, Doppler spread, Doppler shift,
average gain, and/or average delay. In other words, in a case that
two antenna ports are quasi co-located (in a QCL state), the
terminal apparatus can consider the two antenna ports to have the
same long term performance. Note that, for each of the parameters
included in the above-described assist information, one value
(candidate) may be configured, or multiple values (candidates) may
be configured. In a case of multiple values being configured, the
terminal apparatus interprets the parameters as parameters for
indicating a value that may be configured by the base station
apparatus causing interference, and detects (identifies), among the
multiple values, a parameter configured as an interference signal.
Furthermore, the above-described assist information can eliminate
or suppress some or all of the reference signal, PDSCH, and
(E)PDCCH transmitted from the neighbor cell. In addition, the
above-described assist information may be used in a case that
various types of measurement are carried out. The measurement
includes Radio Resource Management (RRM) measurement, Radio Link
Monitoring (RLM) measurement, and Channel State Information (CSI)
measurement.
[0114] In a case of determining the neighbor cell interference to
be LTE, the terminal apparatus can eliminate or suppress the
interference signal by using the assist information. Furthermore,
in a case that the configuration information about subframes being
transmitted by the serving cell is the same as the configuration
information about subframes being transmitted by the neighbor cell
interference, the terminal apparatus can eliminate or suppress the
interference signal by using the assist information. The same
configuration information about subframes refers to, for example, a
case where the subframes of the serving cell and the neighbor cell
are the downlink subframes, and/or have the same parameter set,
and/or have the same CP length. Furthermore, in a case that the
configuration information about subframes being transmitted by the
serving cell is different from the configuration information about
subframes being transmitted by the neighbor cell interference, the
terminal apparatus uses a linear scheme to suppress the
interference instead of using the assist information to eliminate
the neighbor cell interference. The different configuration
information about subframes refers to, for example, a case where
the neighbor cell is transmitting uplink subframes, a case where
parameter sets are different, or a case where CP lengths are
different. Furthermore, in a case that the neighbor cell may
communicate by using a parameter set different from a parameter set
used for communication with the serving cell, the terminal
apparatus uses a linear scheme to suppress the interference instead
of using the assist information to eliminate the neighbor cell
interference. For example, a case where the neighbor cell supports
multiple parameter sets and/or the terminal apparatus does not
eliminate the neighbor cell interference by using the assist
information. Furthermore, for example, in a case that the neighbor
cell supports one parameter set and is communicating by using a
parameter set different from a parameter set for the serving cell,
the terminal apparatus does not eliminate the neighbor cell
interference by using the assist information.
[0115] Note that the communication system according to the present
embodiment can include a System Frame Number (SFN) for frame
synchronization between the base station apparatus and the terminal
apparatus and between terminal apparatuses connected to the base
station apparatus. SFN can be a serial number of a frame
transmitted by the base station apparatus or the terminal
apparatus. The communication system according to the present
embodiment can count the SFN in a unit of a given time length
regardless of the frame structure configured by the base station
apparatus (or radio parameters for defining the frame structure, or
base parameters for determining the parameters for the radio frame,
or the parameter set). In other words, the base station apparatus
according to the present embodiment can perform transmission such
that terminal apparatuses with different frame structures
configured by the base station apparatus each receive a frame with
the same SFN, but receive a different subframe number (or the
number of subframes or OFDM symbols received).
[0116] The base station apparatus/terminal apparatus transmits, to
the terminal apparatus/base station apparatus, a demodulation
reference signal (UE specific reference signal, Demodulation
Reference Signal (DMRS), a downlink demodulation reference signal,
and an uplink demodulation reference signal) used for data
demodulation. The base station apparatus/terminal apparatus uses
the demodulation reference signal to demodulate a data signal. 5G
is required to support various use cases and bandwidths. Examples
of the requirement include a low transmission rate, a high
transmission rate, low delay, high reliability, a high-speed moving
environment, and a high-frequency band communication. Demodulations
are desirably enabled that are respectively suitable for such
various radio environments and transmission schemes. Thus,
desirably, the demodulation reference signals can be flexibly
transmitted (configured). Furthermore, in a case that a common
signal waveform, such as an OFDM, is used in the downlink and the
uplink, the reference signals of the downlink and the uplink
desirably have a common configuration (setting) to some extent.
[0117] The base station apparatus/terminal apparatus can transmit
at least one type of demodulation reference signal. For example, it
is assumed that two types of demodulation reference signals are
available: a basic demodulation reference signal (also referred to
as a first DMRS) and an extended demodulation reference signal
(also referred to as a second DMRS). Furthermore, the first DMRS is
mapped to one or more symbols in earlier part of the slot in order
to suppress delay time for demodulation. Note that simple
references to the demodulation reference signal/DMRS below include
an uplink or downlink demodulation reference signal/DMRS.
Furthermore, the demodulation reference signal/DMRS transmitted by
the base station apparatus is also referred to as the downlink
demodulation reference signal/DMRS. Furthermore, the demodulation
reference signal/DMRS transmitted by the terminal apparatus is also
referred to as the uplink demodulation reference signal/DMRS.
[0118] FIG. 7 is a diagram illustrating an example of mapping of
demodulation reference signals according to the present embodiment.
FIG. 7 illustrates an example of mapping of demodulation reference
signals in 12 subcarriers in a frequency direction and in 14 OFDM
symbols in a time direction. Note that an area represented by one
subcarrier and one OFDM symbol is also referred to as a resource
element. In the example in FIG. 7, the first DMRSs are mapped to
resource elements hatched by lines extending upward and rightward
and resource elements hatched by lines extending downward and
rightward. The second DMRSs are mapped to resource elements hatched
by vertical lines and resource elements hatched by horizontal
lines. Two resource elements hatched by the same lines are spread
and multiplexed by using an Orthogonal Cover Code (OCC). Note that
which resource element to be used for mapping and which OCC to be
used depend on an antenna port number. Note that, in the example in
FIG. 7, the multiplication by OCC is performed in the time domain,
but it can be performed in the frequency domain or in the time
domain and the frequency domain. Furthermore, the first DMRS and
the second DMRS can be independently transmitted. For example, the
first DMRS and the second DMRS are transmitted by using an OCC
sequence length of 2. In this case, the antenna port number through
which the first DMRS is transmitted differs from the antenna port
number through which the second DMRS is transmitted. Furthermore,
the OCC sequence length may differ between a case where the first
DMRS or the second DMRS alone is mapped and a case where both the
first DMRS and the second DMRS are mapped. For example, the OCC
sequence length is 2 in a case that first DMRS or the second DMRS
alone is mapped, and the OCC sequence length is 4 in a case that
both the first DMRS and the second DMRS are mapped. In this case,
the first DMRSs mapped to the resource elements hatched by lines
extending upward and rightward, and the second DMRSs mapped to the
resource elements hatched by vertical lines are spread and
multiplexed by using OCC sequence length of 4. The number of
orthogonal DMRSs thus differs between the case where the first DMRS
or the second DMRS alone is transmitted and the case where both the
first DMRS and the second DMRS are transmitted. The number of
resource elements for DMRS can be flexibly varied according to the
number of streams spatially multiplexed (the number of layers or
the number of ranks), thus enabling efficient communication.
[0119] For example, communication in a high frequency band may
disadvantageously lead to phase noise of an oscillator. The phase
noise causes the phase of receive signal to temporally fluctuate.
In this case, it is desirable to compensate for the phase noise.
The phase noise includes a Common Phase Error (CPE) common to all
subcarriers. In order to compensate for CPE, the demodulation
reference signal, having a high frequency density, that can be
mapped to all of the subcarriers is desirable. Furthermore, the
demodulation reference signal desirably has a high time density to
track a temporal fluctuation of phase noise. An attempt to realize
this by using one demodulation reference signal leads to
consumption of many radio resources, thus degrading efficiency.
Thus, the base station apparatus/terminal apparatus transmits a
demodulation reference signal with a high frequency density and a
demodulation reference signal with a high time density. FIG. 8
illustrates an example of demodulation reference signals according
to the present embodiment. In FIG. 8, the first DMRSs are mapped to
resource elements hatched by lines extending upward and rightward,
and the second DMRSs are mapped to resource elements hatched by
lines extending downward and rightward. As seen in FIG. 8, the
first DMRS is a demodulation reference signal with a high frequency
density, and the second DMRS is a demodulation reference signal
with a high time density. The phase noise compensation can be
efficiently achieved by transmitting two types of demodulation
reference signal as described above.
[0120] For example, communication in a high-speed moving
environment needs a demodulation reference signal with a high time
density to track a channel which is momentarily changed. However,
in a low-speed moving environment, the demodulation reference
signal with a high time density is redundant, thus degrading
communication efficiency. FIG. 9 illustrates an example of mapping
of demodulation reference signals according to the present
embodiment. In FIG. 9, the first DMRSs are mapped to resource
elements hatched by lines extending upward and rightward, and the
second DMRSs are mapped to resource elements hatched by lines
extending downward and rightward. The base station apparatus can
transmit either the first DMRS or the second DMRS to terminal
apparatuses moving at a low speed and transmit the first DMRS and
the second DMRS to terminal apparatuses moving at a high speed.
Thus, the base station apparatus can efficiently transmit the
demodulation reference signals.
[0121] Note that the DMRS is used for purposes other than a
demodulation purpose. For example, in a case that beamforming is
used for communication, a beam needs to be tracked because the
optimum beam is varied by movement or rotation of the terminal
apparatus. DMRS can be used to track the beam. FIG. 10 illustrates
an example of mapping of demodulation reference signals according
to the present embodiment. In FIG. 10, the first DMRSs are mapped
to resource elements hatched by lines extending upward and
rightward, and the second DMRSs are mapped to resource elements
hatched by lines extending downward and rightward. The first DMRS
is transmitted for demodulation, and the second DMRS is transmitted
for beam tracking. In order for a receiving side to track the beam,
the base station apparatus/terminal apparatus transmits the second
DMRS that is beamformed by using the same beam pattern (direction)
for each OFDM symbol. Note that the beam pattern applied to the
second DMRS may be the same as or different from the beam pattern
applied to the first DMRS and data signals. In this case, the
receiving terminal apparatus/base station apparatus can demodulate
the data signals by using the first DMRS, and search for a suitable
receive beam by using the second DMRS. Note that CSI can be
calculated by using the second DMRS. Furthermore, the base station
apparatus/terminal apparatus can also transmit the second DMRS that
is beamformed by using a different beam pattern for each OFDM
symbol. In this case, the base station apparatus/terminal apparatus
having received the second DMRS notifies the base station
apparatus/terminal apparatus having transmitted the second DMRS of
information for indicating the most suitable DMRS (for example,
information for indicating a time/frequency resource such as OFDM
symbol number/slot number/subframe number/subband number including
DMRS with the highest reception SNR). This allows the base station
apparatus/terminal apparatus having transmitted the second DMRS to
identify the suitable transmit beam. Note that the information for
indicating the most suitable DMRS can be included in CSI calculated
by the terminal apparatus based on the second DMRS.
[0122] As described above, the base station apparatus/terminal
apparatus transmits multiple types of DMRS to enable efficient
communication suitable for various radio environments and
transmission schemes.
[0123] The base station apparatus can include the parameters for
the first downlink DMRS and/or second downlink DMRS in control
information to transmit the control information to the terminal
apparatus. The parameters for the first downlink DMRS include some
or all of the number of layers, an antenna port number, a mapping
pattern, frequency density, time density, and a scrambling
identity. The mapping pattern indicates one of candidates for
mapping of DMRSs to resource elements (subcarriers, resource
blocks, subbands, or OFDM symbols). Note that, in a case of
periodic mapping, the mapping pattern indicates the first resource
element (subcarrier, resource block, subband, or OFDM symbol). The
frequency density is the density of DMRSs mapped in the frequency
domain and indicates mapping to all or some of the subcarriers.
Mapping to some of the subcarriers has one or more granularities.
The time density is the density of DMRSs mapped in the time domain
and indicates mapping to all or some of the OFDM symbols. Mapping
to some of the OFDM symbols has one or more granularities. The
scrambling identity is a parameter regarding an initial value for
generating a DMRS sequence. The parameters for the second downlink
DMRS include some or all of the number of layers, an antenna port
number, a mapping pattern, frequency density, time density, and a
scrambling identity. However, some or all of the parameters may
differ between the first DMRS and the second DMRS. For example, the
number of layers in the parameters for the second DMRS is larger
than the number of layers in the parameters for the first DMRS. For
example, the antenna port number in the parameters for the second
DMRS is larger than the antenna port number in the parameters for
the first DMRS. For example, the antenna port number differs
between the parameters for the first DMRS and the parameters for
the second DMRS. For example, the patterns and the number of
mapping patterns that are configurable differ between the first
DMRS and the second DMRS. For example, the first DMRS has one
mapping pattern, and the second DMRS has multiple mapping patterns.
For example, the number of configurations for frequency
density/time density that are configurable in the parameters for
the second DMRS is larger than the number of configurations for
frequency density/time density that are configurable in the
parameters for the first DMRS. Note that the parameters for the
first DMRS and the parameters for the second DMRS include a
configuration for indicating that any DMRS is not transmitted. For
example, the mapping pattern or the time/frequency density
indicates that any DRMS is not transmitted. Note that, in the
parameters for the first DMRS and the parameters for the second
DMRS, the configurable parameters, candidate patterns, and the
number of candidates may vary for each carrier frequency range.
[0124] The base station apparatus can notify a terminal apparatus
of information for indicating that data signals addressed to other
terminal apparatuses than the terminal apparatus are spatially
multiplexed with the data signal addressed to the terminal
apparatus (information for notifying multiplex). The terminal
apparatus can recognize, based on the information for notifying
multiplex, that the data signals addressed to the other terminal
apparatuses than the terminal apparatus are multiplexed with the
data signal addressed to the terminal apparatus. The terminal
apparatus can thus apply, to the receive signal, an interference
suppression process in which the data signals addressed to the
other terminal apparatuses than the terminal apparatus are
considered to be interference signals. Furthermore, the base
station apparatus can notify the terminal apparatus of the
parameters for the first DMRS and/or the parameters for the second
DMRS addressed to the other terminal apparatuses than the terminal
apparatus. The Furthermore, the base station apparatus can notify
the terminal apparatus of the parameters for the first DMRS and/or
the parameters for the second DMRS addressed to the other terminal
apparatuses than the terminal apparatus in a case that a prescribed
radio parameter (for example, a signal waveform, a subcarrier
spacing, or a spatial multiplexing number) indicates a prescribed
value (for example, in a case that the base station apparatus
spatially multiplexes data signals addressed to five or more
terminal apparatuses). Furthermore, the base station apparatus can
notify, to the terminal apparatus, the parameters for the first
DMRS and/or the parameters for the second DMRS addressed to the
other terminal apparatuses than the terminal apparatus, which are
included in the parameters for the first DMRS and/or the parameters
for the second DMRS notified to the terminal apparatus. Note that
the first DMRS can be addressed to the terminal apparatus, and the
second DMRS can be addressed to the other terminal apparatuses than
the terminal apparatus.
[0125] The base station apparatus notifies, to a terminal
apparatus, information for indicating that data signals addressed
to other terminal apparatuses than the terminal apparatus are
spatially multiplexed with the data signal addressed to the
terminal apparatus (multiplexing notification information). No
limitation is imposed on such information. For example, the base
station apparatus may transmit information for indicating to the
terminal apparatus to apply a modulo operation to the receive
signal. Such information can be used as the information for
notifying multiplex. This is because, in a case that the base
station apparatus uses nonlinear precoding to spatially multiplex
data signals, the terminal apparatus needs to apply the modulo
operation to the receive signal. In a case that the base station
apparatus indicates to the terminal apparatus to apply the modulo
operation, the terminal apparatus can recognize that the data
signals addressed to the other terminal apparatuses than the
terminal apparatus are spatially multiplexed with the data signal
addressed to the terminal apparatus.
[0126] Note that the base station apparatus/terminal apparatus may
transmit neither the first DMRS nor the second DMRS. In this case,
the receiving terminal apparatus/base station apparatus demodulates
data signals without using DMRS.
[0127] Note that, in a case of transmitting a data signal, the base
station apparatus may always transmit the first DMRS. In this case,
the first DMRS has fixed time/frequency density. Furthermore,
mapping of the second DMRS is optional. In a case that the first
DMRS has a fixed pattern of time/frequency density, the
time/frequency density may not be indicated (configured) in the
control information. In other words, the control information
includes the time/frequency density of the second DMRS. Note that
the mapping pattern of the first DMRS may vary for each carrier
frequency range. For example, within a carrier frequency range
lower than a prescribed frequency, the first DMRS is discretely
mapped in the frequency direction in the slot (resource block). For
example, within a carrier frequency range higher than a prescribed
frequency, the first DMRS is mapped to all of the subcarriers in
the slot (resource block).
[0128] The base station apparatus can include the parameters for
the first uplink DMRS and/or second uplink DMRS in the control
information to transmit the control information to the terminal
apparatus. The terminal apparatus transmits the uplink DMRS based
on the parameters for the first uplink DMRS and/or the parameters
for the second uplink DMRS transmitted from the base station
apparatus. The parameters for the first uplink DMRS include some or
all of the number of layers, an OCC sequence, a mapping pattern,
frequency density, time density, and a scrambling identity.
Furthermore, the parameters for the second uplink DMRS include some
or all of the number of layers, an OCC sequence, mapping pattern,
frequency density, time density, and a scrambling identity.
[0129] In the uplink, the terminal apparatus can use OFDM and
DFT-spread-OFDM (SC-FDMA) as signal waveforms for transmission.
Note that the terminal apparatus can transmit multiple layers
(streams) in OFDM and transmit one layer (stream) in
DFT-spread-OFDM. In this case, it is desirable that the uplink DMRS
does not depend on the signal waveform. However, OFDM and
DFT-spread-OFDM have different parameters and configurations for
the uplink DMRS. For example, in DFT-spread-OFDM, the second uplink
DMRS is not configured (not transmitted). For example, in
DFT-spread-OFDM, the frequency density may be mapped only to all of
the subcarriers. Note that, in DFT-spread-OFDM, in a case that the
frequency density indicates some of the subcarriers, the signal is
repeated N times in the time domain such that the uplink DMRS is
mapped every N subcarriers, where N is an integer satisfying
N>0. Note that a resultant spectrum is shaped like the teeth of
a comb, thus the frequency density is also referred to as a comb.
Furthermore, the mapping pattern is periodic, thus N candidates for
the mapping pattern are available. Note that, in the uplink, an
OFDM signal and a DFT-spread-OFDM signal may be multiplexed
(collide) and that, in this case, two DMRSs with different signal
waveforms desirably have a common configuration.
[0130] Note that the parameters for the first DMRS and/or the
parameters for the second DMRS include information for indicating
the transmit power. The information for indicating the transmit
power can be transmit power values of the first uplink DMRS and/or
the second uplink DMRS, or a power ratio (power offset) between the
first uplink DMRS and the second uplink DMRS. Note that the
transmit power of the first uplink DMRS and/or the second uplink
DMRS may be configured regardless of the signal waveform or may be
configured for each signal waveform.
[0131] FIG. 11 is a schematic block diagram illustrating a
configuration of the base station apparatus 1A according to the
present embodiment. As illustrated in FIG. 11, the base station
apparatus 1A is configured to include a higher layer processing
unit (higher layer processing step) 101, a controller (controlling
step) 102, a transmitter (transmitting step) 103, a receiver
(receiving step) 104, and a transmit and/or receive antenna 105.
The higher layer processing unit 101 is configured to include a
radio resource control unit (radio resource controlling step) 1011
and a scheduling unit (scheduling step) 1012. The transmitter 103
is configured to include a coding unit (coding step) 1031, a
modulation unit (modulating step) 1032, a downlink reference signal
generation unit (downlink reference signal generating step) 1033, a
multiplexing unit (multiplexing step) 1034, and a radio
transmitting unit (radio transmitting step) 1035. The receiver 104
is configured to include a radio receiving unit (radio receiving
step) 1041, a demultiplexing unit (demultiplexing step) 1042, a
demodulation unit (demodulating step) 1043, and a decoding unit
(decoding step) 1044.
[0132] The higher layer processing unit 101 performs processing of
a Medium Access Control (MAC) layer, a Packet Data Convergence
Protocol (PDCP) layer, a Radio Link Control (RLC) layer, and a
Radio Resource Control (RRC) layer. Furthermore, the higher layer
processing unit 101 generates information necessary for control of
the transmitter 103 and the receiver 104, and outputs the generated
information to the controller 102.
[0133] The higher layer processing unit 101 receives information of
a terminal apparatus, such as a capability of the terminal
apparatus (UE capability), from the terminal apparatus. To
rephrase, the terminal apparatus transmits its function to the base
station apparatus by higher layer signaling.
[0134] Note that in the following description, information of a
terminal apparatus includes information for indicating whether the
terminal apparatus supports a prescribed function, or information
for indicating that the terminal apparatus has completed the
introduction and test of a prescribed function. In the following
description, information of whether the prescribed function is
supported includes information of whether the introduction and test
of the prescribed function have been completed.
[0135] For example, in a case where a terminal apparatus supports a
prescribed function, the terminal apparatus transmits information
(parameters) for indicating whether the prescribed function is
supported. In a case where a terminal apparatus does not support a
prescribed function, the terminal apparatus does not transmit
information (parameters) for indicating whether the prescribed
function is supported. In other words, whether the prescribed
function is supported is reported by whether information
(parameters) for indicating whether the prescribed function is
supported is transmitted. Information (parameters) for indicating
whether a prescribed function is supported may be reported by using
one bit of 1 or 0.
[0136] The radio resource control unit 1011 generates, or acquires
from a higher node, the downlink data (the transport block)
allocated in the downlink PDSCH, system information, the RRC
message, the MAC Control Element (CE), and the like. The radio
resource control unit 1011 outputs the downlink data to the
transmitter 103, and outputs other information to the controller
102. Furthermore, the radio resource control unit 1011 manages
various configuration information of the terminal apparatuses.
Furthermore, the radio resource control unit 1011 configures
(manages) the downlink reference parameter (subcarrier spacing),
the CP length, the number of FFT points, and the like. Furthermore,
the radio resource control unit 1011 configures (manages) the
reference parameter (subcarrier spacing) for the terminal apparatus
(uplink), the CP length, the number of FFT points, and the
like.
[0137] The scheduling unit 1012 determines a frequency and a
subframe to which the physical channels (PDSCH and PUSCH) are
allocated, the coding rate and modulation scheme (or MCS) for the
physical channels (PDSCH and PUSCH), the transmit power, and the
like. The scheduling unit 1012 outputs the determined information
to the controller 102.
[0138] The scheduling unit 1012 generates information to be used
for scheduling the physical channels (PDSCH and PUSCH), based on
the result of the scheduling. The scheduling unit 1012 outputs the
generated information to the controller 102.
[0139] Based on the information input from the higher layer
processing unit 101, the controller 102 generates a control signal
for controlling the transmitter 103 and the receiver 104. The
controller 102 generates the downlink control information based on
the information input from the higher layer processing unit 101,
and outputs the generated information to the transmitter 103.
[0140] The transmitter 103 generates the downlink reference signal
in accordance with the control signal input from the controller
102, codes and modulates the HARQ indicator, the downlink control
information, and the downlink data that are input from the higher
layer processing unit 101, multiplexes PHICH, PDCCH, EPDCCH, PDSCH,
and the downlink reference signal, and transmits a signal obtained
through the multiplexing to the terminal apparatus 2 through the
transmit and/or receive antenna 105.
[0141] The coding unit 1031 codes the HARQ indicator, the downlink
control information, and the downlink data that are input from the
higher layer processing unit 101, in compliance with a
predetermined coding scheme, such as block coding, convolutional
coding, and turbo coding, or in compliance with a coding scheme
determined by the radio resource control unit 1011. The modulation
unit 1032 modulates the coded bits input from the coding unit 1031,
in compliance with a predetermined modulation scheme, such as
Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying
(QPSK), quadrature amplitude modulation (16QAM), 64QAM, and 256QAM,
or in compliance with a modulation scheme determined by the radio
resource control unit 1011.
[0142] The downlink reference signal generation unit 1033
generates, as the downlink reference signal, a sequence, known to
the terminal apparatus 2A, that is determined in accordance with a
rule predetermined based on the physical cell identity (PCI, cell
ID) for identifying the base station apparatus 1A, and the
like.
[0143] The multiplexing unit 1034 multiplexes the modulated
modulation symbol of each channel, the generated downlink reference
signal, and the downlink control information. To be more specific,
the multiplexing unit 1034 maps the modulated modulation symbol of
each channel, the generated downlink reference signal, and the
downlink control information to the resource elements.
[0144] The radio transmitting unit 1035 performs Inverse Fast
Fourier Transform (IFFT) of a modulation symbol resulting from
multiplexing or the like to generate an OFDM symbol, attaches a
Cyclic Prefix (CP) to the generated OFDM symbol to generate a
baseband digital signal (OFDM signal), converts the baseband
digital signal into an analog signal, removes unnecessary frequency
components from the analog signal through filtering, up-converts
the resultant analog signal into a signal of a carrier frequency,
performs power amplification to generate a radio signal, and
outputs the radio signal to the transmit and/or receive antenna 105
for transmission.
[0145] In accordance with the control signal input from the
controller 102, the receiver 104 demultiplexes, demodulates, and
decodes the reception signal received from the terminal apparatus
2A through the transmit and/or receive antenna 105, and outputs
information resulting from the decoding to the higher layer
processing unit 101.
[0146] The radio receiving unit 1041 converts, by down-converting,
an uplink signal received through the transmit and/or receive
antenna 105 into a baseband signal, removes unnecessary frequency
components, controls the amplification level in such a manner as to
suitably maintain a signal level, performs orthogonal demodulation
based on an in-phase component and an orthogonal component of the
received signal, and converts the resulting
orthogonally-demodulated analog signal into a digital signal.
[0147] The radio receiving unit 1041 removes a portion
corresponding to CP from the digital signal resulting from the
conversion. The radio receiving unit 1041 performs Fast Fourier
Transform (FFT) of the signal from which the CP has been removed,
extracts a signal in the frequency domain, and outputs the
resulting signal to the demultiplexing unit 1042.
[0148] The demultiplexing unit 1042 demultiplexes the signal input
from the radio receiving unit 1041 into signals such as PUCCH,
PUSCH, and uplink reference signal. The demultiplexing is performed
based on radio resource allocation information, included in the
uplink grant notified to each of the terminal apparatuses 2, that
is predetermined by the base station apparatus 1A by using the
radio resource control unit 1011.
[0149] Furthermore, the demultiplexing unit 1042 performs channel
compensation for PUCCH and PUSCH. The demultiplexing unit 1042
demultiplexes the uplink reference signal.
[0150] The demodulation unit 1043 performs Inverse Discrete Fourier
Transform (IDFT) of PUSCH, acquires modulation symbols, and
demodulates, for each of the modulation symbols of PUCCH and PUSCH,
a reception signal in compliance with a predetermined modulation
scheme, such as BPSK, QPSK, 16QAM, 64QAM, and 256QAM, or in
compliance with a modulation scheme that the base station apparatus
1A notified to each of the terminal apparatuses 2 in advance by
using the uplink grant.
[0151] The decoding unit 1044 decodes the coded bits of PUCCH and
PUSCH that have been demodulated, at a coding rate, in compliance
with a predetermined coding scheme, that is predetermined or
notified from the base station apparatus 1A to the terminal
apparatus 2 in advance by using the uplink grant, and outputs the
decoded uplink data and uplink control information to the higher
layer processing unit 101. In a case where PUSCH is retransmitted,
the decoding unit 1044 performs the decoding by using the coded
bits that is input from the higher layer processing unit 101 and
retained in an HARQ buffer, and the demodulated coded bits.
[0152] FIG. 12 is a schematic block diagram illustrating a
configuration of the terminal apparatus 2 according to the present
embodiment. As illustrated in FIG. 12, the terminal apparatus 2A is
configured to include a higher layer processing unit (higher layer
processing step) 201, a controller (controlling step) 202, a
transmitter (transmitting step) 203, a receiver (receiving step)
204, a channel state information generation unit (channel state
information generating step) 205, and a transmit and/or receive
antenna 206. The higher layer processing unit 201 is configured to
include a radio resource control unit (radio resource controlling
stop) 2011 and a scheduling information interpretation unit
(scheduling information interpreting step) 2012. The transmitter
203 is configured to include a coding unit (coding step) 2031, a
modulation unit (modulating step) 2032, an uplink reference signal
generation unit (uplink reference signal generating step) 2033, a
multiplexing unit (multiplexing step) 2034, and a radio
transmitting unit (radio transmitting step) 2035. The receiver 204
is configured to include a radio receiving unit (radio receiving
step) 2041, a demultiplexing unit (demultiplexing step) 2042, and a
signal detection unit (signal detecting step) 2043.
[0153] The higher layer processing unit 201 outputs, to the
transmitter 203, the uplink data (the transport block) generated by
a user operation or the like. The higher layer processing unit 201
performs processing of the Medium Access Control (MAC) layer, the
Packet Data Convergence Protocol (PDCP) layer, the Radio Link
Control (RLC) layer, and the Radio Resource Control (RRC)
layer.
[0154] The higher layer processing unit 201 outputs, to the
transmitter 203, information for indicating a terminal apparatus
function supported by the terminal apparatus 2A.
[0155] Furthermore, the radio resource control unit 2011 manages
various configuration information of the terminal apparatuses 2A.
Furthermore, the radio resource control unit 2011 generates
information to be mapped to each uplink channel, and outputs the
generated information to the transmitter 203.
[0156] The radio resource control unit 2011 acquires configuration
information of CSI feedback transmitted from the base station
apparatus, and outputs the acquired information to the controller
202. Furthermore, the radio resource control unit 1011 acquires
configuration information such as a downlink reference parameter
(subcarrier spacing), a CP length, and the number of FFT points
from the base station apparatus, and outputs the configuration
information to the controller 202. Furthermore, the radio resource
control unit 1011 acquires configuration information such as an
uplink reference parameter (subcarrier spacing), a CP length, and
the number of FFT points from the base station apparatus, and
outputs the configuration information to the controller 202.
[0157] The scheduling information interpretation unit 2012
interprets the downlink control information received through the
receiver 204, and determines scheduling information. The scheduling
information interpretation unit 2012 generates control information
in order to control the receiver 204 and the transmitter 203 in
accordance with the scheduling information, and outputs the
generated information to the controller 202.
[0158] Based on the information input from the higher layer
processing unit 201, the controller 202 generates a control signal
for controlling the receiver 204, the channel state information
generation unit 205, and the transmitter 203. The controller 202
outputs the generated control signal to the receiver 204, the
channel state information generation unit 205, and the transmitter
203 to control the receiver 204 and the transmitter 203.
[0159] The controller 202 controls the transmitter 203 to transmit
CSI generated by the channel state information generation unit 205
to the base station apparatus.
[0160] In accordance with the control signal input from the
controller 202, the receiver 204 demultiplexes, demodulates, and
decodes a reception signal received from the base station apparatus
1A through the transmit and/or receive antenna 206, and outputs the
resulting information to the higher layer processing unit 201.
[0161] The radio receiving unit 2041 converts, by down-converting,
a downlink signal received through the transmit and/or receive
antenna 206 into a baseband signal, removes unnecessary frequency
components, controls the amplification level in such a manner as to
suitably maintain a signal level, performs orthogonal demodulation
based on an in-phase component and an orthogonal component of the
received signal, and converts the resulting
orthogonally-demodulated analog signal into a digital signal.
[0162] The radio receiving unit 2041 removes a portion
corresponding to CP from the digital signal resulting from the
conversion, performs fast Fourier transform of the signal from
which the CP has been removed, and extracts a signal in the
frequency domain.
[0163] The demultiplexing unit 2042 demultiplexes the extracted
signal into PHICH, PDCCH, EPDCCH, PDSCH, and the downlink reference
signal. Furthermore, the demultiplexing unit 2042 performs channel
compensation for PHICH, PDCCH, and EPDCCH based on a channel
estimation value of a desired signal obtained from channel
measurement, detects downlink control information, and outputs the
detected downlink control information to the controller 202. The
controller 202 outputs PDSCH and the channel estimation value of
the desired signal to the signal detection unit 2043.
[0164] The signal detection unit 2043, by using PDSCH and the
channel estimation value, detects a signal, and outputs the
detected signal to the higher layer processing unit 201.
[0165] The transmitter 203 generates an uplink reference signal in
accordance with the control signal input from the controller 202,
codes and modulates the uplink data (the transport block) input
from the higher layer processing unit 201, multiplexes PUCCH,
PUSCH, and the generated uplink reference signal, and transmits a
signal resulting from the multiplexing to the base station
apparatus 1A through the transmit and/or receive antenna 206.
[0166] The coding unit 2031 codes the uplink control information
input from the higher layer processing unit 201 in compliance with
a coding scheme such as convolutional coding and block coding.
Furthermore, the coding unit 2031 performs turbo coding in
accordance with information used for the scheduling of PUSCH.
[0167] The modulation unit 2032 modulates the coded bits input from
the coding unit 2031, in compliance with a modulation scheme, such
as BPSK, QPSK, 16QAM, or 64QAM, that is notified by using the
downlink control information, or in compliance with a modulation
scheme predetermined for each channel.
[0168] The uplink reference signal generation unit 2033 generates a
sequence that is determined according to a predetermined rule
(formula), based on a Physical Cell Identity (PCI, also referred to
as a cell ID or the like) for identifying the base station
apparatus 1A, a bandwidth in which the uplink reference signal is
mapped, a cyclic shift notified by using the uplink grant, a
parameter value for generation of a DMRS sequence, and the
like.
[0169] In accordance with the control signal input from the
controller 202, the multiplexing unit 2034 rearranges modulation
symbols of PUSCH in parallel and then performs Discrete Fourier
Transform (DFT) of the rearranged modulation symbols. Furthermore,
the multiplexing unit 2034 multiplexes PUCCH and PUSCH signals and
the generated uplink reference signal for each transmit antenna
port. To be more specific, the multiplexing unit 2034 maps the
PUCCH and PUSCH signals and the generated uplink reference signal
to resource elements for each transmit antenna port.
[0170] The radio transmitting unit 2035 performs Inverse Fast
Fourier Transform (IFFT) of a signal resulting from the
multiplexing and the modulation according to SC-FDMA scheme to
generate an SC-FDMA symbol, attaches CP to the generated SC-FDMA
symbol to generate a baseband digital signal (SC-FDMA signal),
converts the baseband digital signal into an analog signal, removes
unnecessary frequency components, performs conversion to a carrier
frequency by up-conversion, performs power amplification, and
performs output to the transmit and/or receive antenna 206 for
transmission.
[0171] Note that the terminal apparatus 2 can perform modulation
according to not only the SC-FDMA scheme but also the OFDMA
scheme.
[0172] The controller 202 of the terminal apparatus 2 according to
the present embodiment includes a function to control the transmit
power of the uplink signal, generated by the transmitter 203, that
is transmitted to the base station apparatus 1. The controller 202
can calculate, for example, transmit power P.sub.PUSCH,c(i) to
transmit an i-th subframe to be transmitted to a c-th cell, based
on Equation 1.
Equation 1 P PUSCH , c ( i ) = min { P CMAX . c ( i ) , ( 10 log 10
( M PUSCH , c ( i ) ) + P O _ PUSCH , c ( j ) + .alpha. c ( j ) PL
c + .DELTA. TF , c ( i ) + f c ( i ) ) ( 1 ) ##EQU00001##
[0173] P.sub.CMAX,c(i) is a term of maximum allowable transmit
power of the terminal apparatus 2 for transmitting the i-th
subframe to be transmitted to the c-th cell. M.sub.PUSCH,c(i)
represents the number of resource blocks allocated to the terminal
apparatus 2 for transmitting the i-th subframe to be transmitted to
the c-th cell. In other words, the item represented by 10
log.sub.10 (M.sub.PUSCH,c(i)) is an item of the amount of radio
resources allocated to the terminal apparatus 2. P.sub.O_PUSCH,c(j)
is a term of target receive power for transmission to the c-th
cell, which is, in other words, a term of target receive power in a
case that the terminal apparatus 2 transmits the uplink signal to
the base station apparatus 1 including the c-th cell. Note that j
is an integer and that changing j allows P.sub.O_PUSCH,c(j) to have
a different value. .alpha..sub.c(j) is a term (coefficient) of a
propagation loss compensation between the base station apparatus 1
including the c-th cell and the terminal apparatus 2. Note that j
is an integer and that changing j allows .alpha..sub.c(j) to have a
different value. PL.sub.c(j) is a term of the propagation loss
between the base station apparatus 1 including the c-th cell and
the terminal apparatus 2. .DELTA..sub.TF,c(i) is a term of a
modulation scheme applied by the modulation unit 2032 to the signal
included in the i-th subframe to be transmitted to the c-th cell.
f.sub.c(i) is a term of a control error caused in a case that the
controller 202 controls the transmit power of the signal included
in the i-th subframe to be transmitted to the c-th cell. Variable
names of the terms of Equation 1 are designated for convenience of
description, and the operation of the terminal apparatus 2
according to the present embodiment is not limited due to the
variable names. Each of the variable names can be any selected
name.
[0174] The controller 202 of the terminal apparatus 2 according to
the present embodiment can control the transmit power based on the
frame structure (or radio parameters for defining the frame
structure, or base parameters for determining the parameters for
the radio frame, or parameter set, or reference parameters, or
reference parameter set) configured by the multiplexing unit 2034
(transmitter 203). Specifically, at least one of the multiple terms
included in Equation 1 is associated with the frame structure
configured by the multiplexing unit 2034.
[0175] The controller 202 according to the present embodiment can
control the transmit power in a subframe length as a unit of
control as indicated by Equation 1. The controller 202 can control
the transmit power in any unit of control, such as a slot length,
an OFDM symbol length, a SC-FDMA symbol length, and a frame length,
instead of the subframe length. The controller 202 according to the
present embodiment can configure the unit for controlling the
transmit power based on the frame structure configured by the
multiplexing unit 2034. For example, a 100th frame structure may
have a long subcarrier spacing, and a 200th frame structure may
have a shorter subcarrier spacing than the 100th frame structure.
In such a case, the time interval (time granularity) at which the
controller 202 controls the transmit power for the 100th frame
structure can be shorter than that for the 200th frame structure.
Such control allows the controller 202 to more flexibly control the
transmit power of signal including a frame structure of which frame
length (symbol length) is short. Furthermore, the controller 202
according to the present embodiment can change, for each frame
structure, the time unit for calculating the multiple terms
included in Equation 1.
[0176] The controller 202 according to the present embodiment can
configure, for each frame structure, the term of the maximum
allowable transmit power in Equation 1. For example, the controller
202 can configure the maximum allowable transmit power for a frame
structure that needs to have high reliability to be higher than the
maximum allowable transmit power for other frame structures. With
such a configuration, uplink signals transmitted to the base
station apparatus 1 by using a frame structure with high maximum
allowable transmit power can be received with higher reception
quality by the base station apparatus 1, compared to signals
transmitted by using other frame structures. Note that, in a case
that high reliability is required (for example, in a case of a
prescribed frame structure), based on an indication or
configuration from the base station apparatus 1, the terminal
apparatus 2 can constantly use the maximum allowable transmit power
for transmission without controlling the transmit power.
[0177] The controller 202 according to the present embodiment can
configure, for each frame structure, the term of the amount of
radio resources allocated to the terminal apparatus 2 in Equation
1. Furthermore, the controller 202 according to the present
embodiment can configure the term of the amount of radio resources
by using a common unit regardless of the frame structure. For
example, the controller 202 according to the present embodiment can
configure the term of the amount of radio resources by using a unit
of RB-2 in which the frequency bandwidth is fixed per unit. Since
the bandwidth per unit is uniquely fixed in a unit of RB-2, a
difference in subcarrier spacing which is one of the parameters of
the frame structure, leads to a difference in the number of
subcarriers included in RB-2. The use of the common frequency unit
allows the controller 202 to configure the term of the amount of
radio resources regardless of the frame structure.
[0178] The controller 202 according to the present embodiment can
configure, for each frame structure, the term of the target receive
power in Equation 1. For example, the controller 202 can configure
the target receive power for a prescribed frame structure to be
higher or lower than the target receive power configured for other
frame structures than the prescribed frame structure. The
controller 202 configures higher target receive power for the
prescribed frame structure to improve reception quality of signals
with the prescribed frame structure. On the other hand, the
controller 202 configures lower target receive power for the
prescribed frame structure to reduce interference power, caused by
signals with the prescribed frame structure, that affects other
cells or neighbor channels.
[0179] The controller 202 according to the present embodiment can
further add, to the term of the target receive power in Equation 1,
a term of a gain resulting from beamforming performed by the base
station apparatus 1 and the terminal apparatus 2. For example, the
controller 202 can define B.sub.c(i) as a compensation coefficient
for the beamforming gain to configure
B.sub.c(i).times.P.sub.O_PUSCH,c(j) as the term of the target
receive power. In a case that the prescribed frame structure is
configured, the controller 202 can take into account the
compensation coefficient for the beamforming gain. The controller
202 can determine the compensation coefficient for the beamforming
gain depending on whether the antenna 206 of the terminal apparatus
2 or the antenna 105 of the base station apparatus 1 performs
beamforming. For example, the controller 202 can configure
B.sub.c(i) to 1 in a case that beamforming is not performed and
configure B.sub.c(i) to a real number smaller than or equal to 1
and greater than 0 in a case that beamforming is performed.
[0180] The controller 202 can configure, for each frame structure,
the term of the propagation loss compensation in Equation 1. The
controller 202 can configure, for each frame structure, a value to
be included in a set of values that can be configured for the term
of the propagation loss compensation.
[0181] The controller 202 can configure, for each frame structure,
the term of the propagation loss in Equation 1. For example, in a
case that a prescribed frame structure is configured, the
controller 202 can take into account the compensation coefficient
of the beamforming gain for the term of the propagation loss. For
example, in the case that the prescribed frame structure is
configured, the controller 202, in a case of configuring the
propagation loss, can measure the propagation loss with the gain
resulting from the beamforming performed by the base station
apparatus 1 and the terminal apparatus 2 taken into account.
[0182] The controller 202 can further add a term of beamforming to
Equation 1. As the term of the beamforming, the controller 202 can
configure the gain resulting from the beamforming performed by the
base station apparatus 1 and the terminal apparatus 2. In a case
that a prescribed frame structure is configured, the controller 202
can configure a value selected from multiple values for the term of
the beamforming. In the case that the prescribed frame structure is
configured, the controller 202 can configure a prescribed value
(for example, 0) for the term of the beamforming. The controller
202 can configure a difference between the gain resulting from the
beamforming performed by the base station apparatus 1 and the
terminal apparatus 2 and the gain of reference beamforming. As the
gain of the reference beamforming, the controller 202 can use
information about a reception gain of a common reference signal or
a signal including common control information transmitted by the
base station apparatus 1. The controller 202 can use, for the
information about the gain resulting from the beamforming, the
information about the reception gain of a specific reference signal
or a signal including data addressed to the terminal apparatus
2.
[0183] In a case of controlling the transmit power of an uplink
signal with a prescribed frame structure based on Equation 1, the
controller 202 can calculate the multiple terms included in
Equation 1 by using values configured for the prescribed frame
structure. However, the controller 202 can configure at least one
of the multiple terms of Equation 1 to a common value regardless of
whether a different frame structure is configured. For example, the
propagation loss calculated for a frame structure can be used as
the propagation loss for another frame structure.
[0184] In a case that the controller 202 controls the transmit
power of an uplink signal with a prescribed frame structure based
on Equation 1 and that the terminal apparatus 2 simultaneously uses
multiple component carriers (by carrier aggregation) to transmit
the uplink signal, the controller 202 can calculate transmit power
for each component carrier and control the transmit power based on
the total transmit power value. In this case, in a case of totaling
the transmit power values for the respective component carriers,
the controller 202 can weight the transmit power value for each
component carrier and total the weighted transmit power values,
instead of simply totaling the transmit power values. The
controller 202 can determine a weighting factor for each component
carrier based on the frame structure configured for the component
carrier. Of course, the controller 202 according to the present
embodiment can control the transmit power in a case that carrier
aggregation of multiple component carriers for which different
frame structures are configured are performed.
[0185] In a case that the controller 202 controls the transmit
power of an uplink signal with a prescribed frame structure based
on Equation 1 and that the terminal apparatus 2 simultaneously
transmits, as the uplink signals, at least a part of the data
signal and a part of the control signal in different frequency
resources, the controller 202 can subtract the transmit power
required for transmission of the control signal from the term of
the maximum allowable transmit power in Equation 1. Such a control
allows the terminal apparatus 2 to avoid a disadvantageous failure
to transmit the control signal. The controller 202 according to the
present embodiment can configure, based on the frame structure
configured for a signal including the control signal, the transmit
power, required for transmission of the control signal, that is
subtracted from the term of the maximum allowable transmit power in
Equation 1.
[0186] The receiver 204 (higher layer processing unit 201) of the
terminal apparatus 2 can acquire, from the base station apparatus
1, control information about at least one of the multiple terms
included in Equation 1. The terminal apparatus 2 can acquire the
control information from information included in Master Information
Block (MIB) or System Information Block (SIB) broadcasted via
broadcast information (e.g., a Broadcast CHannel (BCH)) of the base
station apparatus 1. The terminal apparatus 2 can acquire the
control information from control information (e.g., DCI notified
via PDCCH) of the physical layer transmitted by the base station
apparatus 1. A period at which the terminal apparatus 2 acquires
the control information from the base station apparatus 1 may vary
for each frame structure configured.
[0187] The control information, acquired by the terminal apparatus
2, that is information about at least one of the multiple terms
included in Equation 1 can be associated with a prescribed frame
structure of multiple frame structures. The controller 202 can
configure, based on the acquired control information associated
with the prescribed frame structure, at least one of the multiple
items, included in Equation 1, that is associated with other frame
structures than the prescribed frame structure.
[0188] The base station apparatus 1 can notify the terminal
apparatus 2 of the control information, used for the terminal
apparatus 2 to control the transmit power, that is information
about at least one of the multiple terms included in Equation 1.
The control information notified to the terminal apparatus 2 by the
base station apparatus 1 and the notification method can be
determined based on the frame structure configured by the base
station apparatus 1. The base station apparatus 1 can broadcast the
control information, associated with the prescribed frame
structure, that is included in Master Information Block (MIB) or
System Information Block (SIB) broadcasted via broadcast
information (e.g., Broadcast CHannel (BCH)). The base station
apparatus 1 can transmit the control information, associated with
the prescribed frame structure, that is included in the control
information of the physical layer (e.g., a signal including DCI and
a TPC command notified via PDCCH). The period at which the base
station apparatus 1 broadcasts or transmits the signal including
the control information may vary for each frame structure
configured. Note that the base station apparatus 1 can be
configured not to simultaneously transmit the multiple pieces of
control information associated with different frame structures.
Furthermore, the base station apparatus 1 can be configured to
notify the terminal apparatus 2 of the control information
associated with the prescribed frame structure only by using the
signal with the prescribed frame structure.
[0189] In a case of controlling the transmit power, the controller
202 according to the present embodiment can configure the transmit
power per subcarrier to be different for each frame structure. For
example, the transmit power per subcarrier in a frame structure
with a subcarrier spacing of 15 kHz can be configured to be half
the transmit power per subcarrier in a frame structure with a
subcarrier spacing of 30 kHz. The control of the transmit power by
the controller 202 allows the transmit power, per unit frequency,
of the uplink signal transmitted by the terminal apparatus 2 (e.g.,
transmit power per 1 MHz or transmit power spectral density) to be
constant. The above-described control allows, for example, flatness
(smoothness) of a signal spectrum of a signal transmitted by the
terminal apparatus 2 to be improved.
[0190] The terminal apparatus 2 according to the present embodiment
can notify the base station apparatus 1 of information about the
configuration capability of the transmit power supported by the
terminal apparatus 2. The information about the configuration
capability can be Power Headroom (PH). The controller 202 of the
terminal apparatus 2 according to the present embodiment can
calculate, for example, the power headroom PH.sub.type1,c(i) for
transmitting an ith subframe to be transmitted to a cth cell based
on Equation 2.
Equation 2
P.sub.PUSHC,c(i)=P.sub.CMAX,c(i)-{10
log.sub.10(M.sub.PUSCH,c(i))+P.sub.O_PUSCH,c(j)+.alpha..sub.c(j)PL.sub.c+-
.DELTA..sub.TF,c(i)+f.sub.c(i)} (2)
[0191] As indicated by Equation 2, PH is expressed by a difference
between the maximum allowable transmit power of the terminal
apparatus 2 and the transmit power of the terminal apparatus 2
requested by the base station apparatus 1. A positive PH value
indicates that the terminal apparatus 2 still has remaining
transmit power (the terminal apparatus 2 can transmit signals at
transmit power higher than the current transmit power). A PH of
zero indicates that the terminal apparatus 2 does not have
remaining transmit power (the terminal apparatus 2 cannot transmit
signals at higher transmit power). A negative PH value indicates
that the terminal apparatus 2 cannot transmit signals at the
transmit power requested by the base station apparatus 1).
Notifying, by the terminal apparatus 2, PH to the base station
apparatus 1 allows the base station apparatus 1 to recognize the
amount of radio resources to be allocated to the terminal apparatus
2. Note that, in a case of notifying, by the terminal apparatus 2
to which no resource is allocated, PH to the base station apparatus
1, the terminal apparatus 2 can calculate PH without taking into
account the amount of radio resources. Furthermore, in a case that
a resource has been allocated but transmission has failed for some
reason, the terminal apparatus 2 can calculate PH with the
allocated resources taken into account.
[0192] The terminal apparatus 2 according to the present embodiment
can notify the base station apparatus 1 of PH for each frame
structure. The period at which the terminal apparatus 2 notifies
the base station apparatus 1 of PH may vary for each frame
structure. The terminal apparatus 2 can notify, to the base station
apparatus 1, only PH regarding the frame structure requested by the
base station apparatus 1.
[0193] Furthermore, the base station apparatus 1 and the terminal
apparatus 2 can predetermine a prescribed frame structure for which
the PH is to be calculated. In this case, the terminal apparatus 1
can calculate, based on PH, associated with the prescribed frame
structure, that is notified by the terminal apparatus 2, PHs
associated with other frame structures than the prescribed frame
structure.
[0194] Note that the term subtracted from the maximum allowable
transmit power in Equation 2 includes all of the multiple terms,
included in Equation 1, that are used for the controller 202 to
calculate the transmit power. In a case of calculating PH, the
controller 202 according to the present embodiment may not
necessarily include all of the multiple terms included in Equation
1, in the term subtracted from the maximum allowable transmit
power. Terms that the controller 202 includes in the term
subtracted from the maximum allowable transmit power may be a
different combination of terms for each frame structure configured
or may be common to the frame structures.
[0195] Note that the terminal apparatus 2 according to the present
embodiment can constantly transmit uplink signals at the maximum
allowable transmit power of the terminal apparatus 2 in a
prescribed frame structure. In this case, PH is always 0 in a case
that the prescribed frame structure is configured, thus the
terminal apparatus 2 may not notify the base station apparatus 1 of
PH. In other words, the terminal apparatus 2 according to the
present embodiment can be configured not to transmit PH in a case
that a prescribed frame structure is configured.
[0196] A program running on an apparatus according to an aspect of
the present invention may serve as a program that controls a
Central Processing Unit (CPU) and the like to cause a computer to
operate in such a manner as to realize the functions of the
above-described embodiment according to the present invention.
Programs or the information handled by the programs are temporarily
stored in a volatile memory such as a Random Access Memory (RAM), a
non-volatile memory such as a flash memory, a Hard Disk Drive
(HDD), or any other storage device system.
[0197] Note that a program for realizing functions of an embodiment
related to an aspect of the present invention may be recorded in a
computer-readable recording medium. The functions may be realized
by causing a computer system to read the program recorded in the
recording medium for execution. It is assumed that the "computer
system" refers to a computer system built into the apparatuses, and
the computer system includes an operating system and hardware
components such as a peripheral device. Furthermore, the
"computer-readable recording medium" may be any of a semiconductor
recording medium, an optical recording medium, a magnetic recording
medium, a medium dynamically retaining a program for a short time,
or any other computer-readable recording medium.
[0198] Furthermore, each functional block or various
characteristics of the apparatuses used in the above-described
embodiment may be implemented or performed in an electric circuit,
for example, an integrated circuit or multiple integrated circuits.
An electric circuit designed to perform the functions described in
the present specification may include a general-purpose processor,
a Digital Signal Processor (DSP), an Application Specific
Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA),
or other programmable logic devices, discrete gates or transistor
logic, discrete hardware components, or a combination thereof. The
general-purpose processor may be a microprocessor or may be a
processor of known type, a controller, a micro-controller, or a
state machine instead. The above-mentioned electric circuit may be
constituted of a digital circuit or an analog circuit. Furthermore,
in a case that with advances in semiconductor technology, a circuit
integration technology appears that replaces the present integrated
circuits, one or more aspects of the present invention can use a
new integrated circuit based on the technology.
[0199] Note that the invention of the present patent application is
not limited to the above-described embodiments. In the embodiment,
apparatuses have been described as an example, but the invention of
the present application is not limited to these apparatuses, and is
applicable to a terminal apparatus or a communication apparatus of
a fixed-type or a stationary-type electronic apparatus installed
indoors or outdoors, for example, an AV apparatus, a kitchen
apparatus, a cleaning or washing machine, an air-conditioning
apparatus, office equipment, a vending machine, and other household
apparatuses.
[0200] The embodiments of the present invention have been described
in detail above referring to the drawings, but the specific
configuration is not limited to the embodiments and includes, for
example, an amendment to a design that falls within the scope that
does not depart from the gist of the present invention.
Furthermore, various modifications can be made to the aspect of the
present invention within the scope of the present invention defined
by claims, and embodiments that are made by suitably combining
technical means disclosed according to the different embodiments
are also included in the technical scope of the present invention.
Furthermore, a configuration in which constituent elements,
described in the respective embodiments and having mutually the
same effects, are substituted for one another is also included in
the technical scope of the present invention.
INDUSTRIAL APPLICABILITY
[0201] An aspect of the present invention can be suitably used in a
base station apparatus, a terminal apparatus, and a communication
method. An aspect of the present invention can be utilized, for
example, in a communication system, communication equipment (for
example, a cellular phone apparatus, a base station apparatus, a
radio LAN apparatus, or a sensor device), an integrated circuit
(for example, a communication chip), or a program.
REFERENCE SIGNS LIST
[0202] 1A Base station apparatus [0203] 2A, 2B Terminal apparatus
[0204] 101 Higher layer processing unit [0205] 102 Controller
[0206] 103 Transmitter [0207] 104 Receiver [0208] 105 Transmit
and/or receive antenna [0209] 1011 Radio resource control unit
[0210] 1012 Scheduling unit [0211] 1031 Coding unit [0212] 1032
Modulation unit [0213] 1033 Downlink reference signal generation
unit [0214] 1034 Multiplexing unit [0215] 1035 Radio transmitting
unit [0216] 1041 Radio receiving unit [0217] 1042 Demultiplexing
unit [0218] 1043 Demodulation unit [0219] 1044 Decoding unit [0220]
201 Higher layer processing unit [0221] 202 Controller [0222] 203
Transmitter [0223] 204 Receiver [0224] 205 Channel state
information generation unit [0225] 206 Transmit and/or receive
antenna [0226] 2011 Radio resource control unit [0227] 2012
Scheduling information interpretation unit [0228] 2031 Coding unit
[0229] 2032 Modulation unit [0230] 2033 Uplink reference signal
generation unit [0231] 2034 Multiplexing unit [0232] 2035 Radio
transmitting unit [0233] 2041 Radio receiving unit [0234] 2042
Demultiplexing unit [0235] 2043 Signal detection unit
* * * * *