JP2014072583A - Control information transmitter and control information receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify control messages for notifying a radio terminal of an RB to which an ePDCCH can be assigned and to prevent throughput degradation of a PDSCH.SOLUTION: A control information transmitter 10 notifies a radio terminal 2 of radio resources to which a "Localized ePDCCH" can be assigned using "Resource allocation type 0", or notifies the radio terminal 2 of radio resources to which a "Distributed ePDCCH" can be assigned using "Resource allocation type 1".

Description

  The present invention relates to a control information transmitting device and a control information receiving device according to a wireless communication system.

  Wireless interface standardization organizations (for example, 3GPP (3rd Generation Partnership Project)) are represented by LTE (Long Term Evolution), aiming to further improve frequency utilization efficiency from third-generation systems such as W-CDMA. Standardization work is underway for the third generation successor system.

  In LTE, OFDMA (Orthogonal Frequency Division Multiple Access) is used as a radio access scheme in a downlink in which transmission is performed from a base station to a terminal. In OFDMA, the system bandwidth can be divided into a plurality of subcarrier groups, and data channels can be allocated to a plurality of terminals for each subcarrier group. Therefore, in the OFDMA system, a “resource element” that is a minimum unit of radio resources is defined by a time-axis OFDM symbol and a frequency-axis subcarrier.

  In the downlink of LTE, a downlink control channel called PDCCH (Physical Downlink Control Channel) is used to notify the result of radio resource allocation to the terminal from the base station to the terminal. In the LTE downlink, a subframe is composed of 14 OFDM symbols. In LTE downlink subframes, the downlink data channel (PDSCH: Physical Downlink Shared Channel) and the PDCCH are time-multiplexed, the PDCCH uses the first three OFDM symbols at the maximum, and the PDSCH is not a PDCCH OFDM symbol. Use OFDM symbols. FIG. 5 shows a conceptual diagram of time multiplexing of PDCCH and PDSCH.

  In LTE-Advanced (LTE Rel-11 and later), an advanced PDCCH (ePDCCH) is added to the conventional PDSCH region (legacy PDSCH region) mainly for the purpose of expanding control channel capacity and avoiding radio interference of the control channel. ) Is being considered. FIG. 6 shows a conceptual diagram of the ePDCCH arrangement.

By the RAN1 meeting in August 2012, the following agreements related to ePDCCH have been obtained.
(1) Supports “Localized ePDCCH” allocated to continuous radio resources.
(2) Support “Distributed ePDCCH” to be allocated to distributed radio resources.
(3) A radio resource capable of arranging “Localized ePDCCH” and a radio resource capable of arranging “Distributed ePDCCH” are configured separately.

  Non-Patent Document 1 describes a method called “Resource allocation type 0” and a method called “Resource allocation type 1” as methods for allocating PDSCH radio resources to terminals.

3GPP TS36.213

  In order for the terminal to perform blind decoding on the ePDCCH arranged in the PDSCH region, the base station notifies the terminal in advance of a radio resource (RB: resource block) on which the ePDCCH can be arranged. There is a need. For this reason, the simplification of the control message for notifying the RB that can arrange the ePDCCH is an issue. Another problem is to prevent a reduction in PDSCH throughput.

  The present invention has been made in view of such circumstances, and can simplify a control message for notifying an RB that can place an ePDCCH, and can prevent a decrease in PDSCH throughput. Another object is to provide a control information transmitting device and a control information receiving device.

  In order to solve the above-described problem, the control information transmitting apparatus according to the present invention uses “Resource allocation type 0” to notify a radio terminal of radio resources in which “Localized ePDCCH” can be arranged, and “Resource allocation type 1 ”is used to notify a radio terminal of a radio resource capable of arranging“ Distributed ePDCCH ”.

  The control information receiving apparatus according to the present invention is notified from the control information received from the base station using “Resource allocation type 0”, information identifying a radio resource capable of arranging “Localized ePDCCH”, and “Resource information specifying radio resources that can be allocated “Distributed ePDCCH”, which is notified using “allocation type 1”, is acquired.

  The control information transmission apparatus according to the present invention uses “Resource allocation type 1” to notify a radio terminal of radio resources in which “Localized ePDCCH” can be allocated, and uses “Resource allocation type 1” to “Distributed ePDCCH”. ”Is notified to the wireless terminal.

  The control information receiving apparatus according to the present invention is notified from the control information received from the base station using “Resource allocation type 1”, information identifying a radio resource capable of arranging “Localized ePDCCH”, and “Resource information specifying radio resources that can be allocated “Distributed ePDCCH”, which is notified using “allocation type 1”, is acquired.

  According to the present invention, it is possible to simplify a control message for notifying an RB on which ePDCCH can be arranged, and to prevent a reduction in PDSCH throughput.

It is a schematic diagram which shows the structural example of the radio | wireless communications system which concerns on one Embodiment of this invention. It is an example of the correspondence of a system band and RBG size. FIG. 5 is a conceptual diagram of “Resource allocation type 0”. It is a conceptual diagram of "Resource allocation type 1." It is a conceptual diagram of time multiplexing of PDCCH and PDSCH. It is a conceptual diagram of arrangement | positioning of ePDCCH.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram illustrating a configuration example of a wireless communication system according to an embodiment of the present invention. The radio communication system according to the present embodiment is compatible with LTE. In FIG. 1, the wireless communication system includes a base station 1 and a wireless terminal 2. The base station 1 includes a control information transmission device 10. The wireless terminal 2 includes a control information receiving device 20.

  The control information transmitting apparatus 10 creates control information (control message) to be transmitted on the LTE downlink. The control information transmitted on the LTE downlink includes ePDCCH information. The control information transmitted from the base station 1 on the LTE downlink is received by the wireless terminal 2. The control information receiver 20 receives control information on the LTE downlink. The control information received on the LTE downlink includes ePDCCH information. The control information receiving apparatus 20 acquires ePDCCH information from the control information received on the LTE downlink.

  Hereinafter, the control information transmission method according to the present embodiment will be described.

  In the control information transmission method according to the present embodiment, ePDCCH information is transmitted. The ePDCCH information includes information for specifying a radio resource (RB) in which the ePDCCH can be arranged. The types of ePDCCH include “Localized ePDCCH” and “Distributed ePDCCH”. For this reason, the ePDCCH information includes information for specifying an RB in which “Localized ePDCCH” can be allocated, and information for specifying an RB in which “Distributed ePDCCH” can be allocated. Based on the ePDCCH information, the wireless terminal 2 identifies an RB in which “Localized ePDCCH” can be placed. Based on the ePDCCH information, the radio terminal 2 identifies an RB in which “Distributed ePDCCH” can be placed.

  In the present embodiment, “Resource allocation type 0” or “Resource allocation type 1” is used as a method of notifying the wireless terminal 2 of ePDCCH information. “Resource allocation type 0” and “Resource allocation type 1” are disclosed in Non-Patent Document 1. The outline of “Resource allocation type 0” and “Resource allocation type 1” will be described below.

[Resource allocation type 0]
・ Allocate RBs to terminals in units of “Resource Block Group: RBG”.
The number of consecutive RBs included in the RBG (P: RBG size) depends on the system bandwidth (N ^DL _RB ).
FIG. 2 shows an example of the correspondence between the system band and the RBG size.

The number of RBGs (N _RBG ) is calculated by equation (1).

Example of calculating the number of RBGs (N _RBG ):
In the case of “system band (N ^DL _RB ) = 11” and “RBG size (P) = 2”, “RBG number (N _RBG ) = 6”.

  FIG. 3 is a conceptual diagram of “Resource allocation type 0”. In the example of FIG. 3, there are 11 RBs and 6 RBGs. In the example of FIG. 3, if an RB is assigned to a terminal, an 11-bit bitmap is required to notify the assigned RB to the terminal. On the other hand, if the resource allocation type 0 is assigned to the terminal in units of RBGs, a 6-bit bitmap may be used to notify the terminal of the assigned RBG. For example, when RBG3 and RBG6 are assigned to a certain terminal, the bitmap transmitted to the terminal is “001001” (however, bit “1” indicates that it is allocated, and bit “0” indicates that it is not allocated) ). Thereby, the control message for notifying the terminal of the allocated RB can be simplified.

[Resource allocation type 1]
-Divide all RBs into subsets composed of RBG size (P) RBGs.
Of the bit map composed of RBG number (N _RBG , (1)) bits, BIT_P (2)) bits are used for subset selection, and one bit is shifted right or left N ^TYPE1 _RB (Expression (3)) bits are used for selecting RBs in the subset.

FIG. 4 is a conceptual diagram of “Resource allocation type 1”. In the example of FIG. 4, there are 11 RBs and 6 RBGs. In the example of FIG. 4, if an RB is assigned to a terminal, an 11-bit bitmap is required to notify the assigned RB to the terminal. On the other hand, according to “Resource allocation type 1”, the bitmap can be simplified. A specific example is given. When “System Band (N ^DL _RB ) = 11” and “RBG Size (P) = 2” and “RBG Number (N _RBG ) = 6”, the RBG is composed of RBG “6”. Divide into subsets. In this case, when the 6-bit bitmap is “010100”, for example, the last bit “0” indicates the left shift, and the terminal assigns the second RB of RBG1 and the second RB of RBG3 in Subset1. Be notified. Also, when the 6-bit bitmap is “010101”, for example, the last bit “1” indicates a right shift, and the terminal assigns the second RB of RBG5 and the second RB of RBG3 in Subset1. Will be notified. Thereby, the control message for notifying the terminal of the allocated RB can be simplified.

  This completes the description of the outline of “Resource allocation type 0” and “Resource allocation type 1”.

  Next, an ePDCCH information notification method according to the control information transmission method of this embodiment will be described. Hereinafter, an example is given and demonstrated.

[Localized ePDCCH]
“Localized ePDCCH” is arranged in continuous RBs. “Localized ePDCCH” is preferably reserved as an RB in which consecutive PRBs (Physical Resource Blocks) can be arranged. In the first embodiment, “Resource allocation type 0” is used to notify the radio terminal 2 of an RB in which “Localized ePDCCH” can be arranged.

"Distributed ePDCCH"
“Distributed ePDCCH” is arranged in distributed RBs. “Distributed ePDCCH” preferably reserves distributed PRBs as RBs that can be arranged. In the first embodiment, “Resource allocation type 1” is used to notify the radio terminal 2 of RBs in which “Distributed ePDCCH” can be arranged. When “Resource allocation type 1” is used, there is a restriction that RBs in which “Distributed ePDCCH” can be arranged are limited to some bands.

[Localized ePDCCH]
In the second embodiment, “Resource allocation type 1” is used to notify the radio terminal 2 of an RB in which “Localized ePDCCH” can be arranged. When “Resource allocation type 1” is used, there are no restrictions on configuring RBG units. When “Resource allocation type 1” is used, there is a restriction that RBs in which “Localized ePDCCH” can be arranged are limited to some bands.

"Distributed ePDCCH"
In the same manner as in the first embodiment, “Resource allocation type 1” is used to notify the radio terminal 2 of RBs in which “Distributed ePDCCH” can be arranged.

  As described above, according to the present embodiment, it is possible to simplify information for specifying an RB in which “Localized ePDCCH” can be arranged. In addition, it is possible to simplify information for identifying RBs on which “Distributed ePDCCH” can be placed. Furthermore, by using the allocation type of PDSCH, the compatibility of PDSCH with “Localized ePDCCH” and “Distributed ePDCCH” is good. As a result, it is possible to simplify the control message for notifying the radio terminal 2 of the RBs on which the ePDCCH can be arranged, and to prevent a reduction in the PDSCH throughput.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

DESCRIPTION OF SYMBOLS 1 ... Base station, 2 ... Wireless terminal, 10 ... Control information transmitter, 20 ... Control information receiver

Claims (4)

Use "Resource allocation type 0" to notify the wireless terminal of the wireless resources that can be allocated "Localized ePDCCH"
Use "Resource allocation type 1" to notify the wireless terminal of the wireless resources that can distribute "Distributed ePDCCH".
A control information transmitting apparatus characterized by the above. From the control information received from the base station,
Information identifying radio resources that can be allocated "Localized ePDCCH", notified using "Resource allocation type 0";
To acquire information that identifies radio resources that can be allocated “Distributed ePDCCH”, which is notified using “Resource allocation type 1”.
A control information receiving apparatus. Use "Resource allocation type 1" to notify the wireless terminal of the wireless resources that can be allocated "Localized ePDCCH"
Use "Resource allocation type 1" to notify the wireless terminal of the wireless resources that can distribute "Distributed ePDCCH".
A control information transmitting apparatus characterized by the above. From the control information received from the base station,
Information specifying the radio resource that can be allocated "Localized ePDCCH" notified using "Resource allocation type 1",
To acquire information that identifies radio resources that can be allocated “Distributed ePDCCH”, which is notified using “Resource allocation type 1”.
A control information receiving apparatus.

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