KR20150088741A - Apparatus for discovery signal transmission on LTE small cell - Google Patents

Abstract

The present invention relates to a method for transmitting a discovery signal to enable a terminal to reliably recognize a small cell base station. More specifically, the present invention relates to an apparatus for transmitting and receiving a discovery signal of an LTE small cell, which effectively sets a discovery signal of the small cell base station. The apparatus for transmitting and receiving a discovery signal of an LTE small cell comprises a small cell base station which transmits a discovery reference signal to a terminal.

Description

[0001] Apparatus for discovery signal transmission on LTE small cell [

The present invention relates to an apparatus for transmitting and receiving a discovery signal of an LTE small cell, and more particularly, to a method for transmitting a discovery signal so that a terminal reliably recognizes a small cell base station. That is, the present invention relates to a discovery signal transmitting / receiving apparatus of an LTE small cell that efficiently sets a discovery signal of a small cell base station.

Due to the rapid expansion of mobile computing based on wireless Internet technology, a dramatic increase in wireless network capacity is required, and traffic usage of mobile users is expected to continue to increase sharply in the future. A typical solution to meet the requirements of such explosive traffic growth is to consider applying an evolved physical layer technique or allocating additional spectrum. However, the physical layer technology has reached a theoretical limit and the capacity increase of the cellular network through the allocation of additional spectrum can not be a fundamental solution.

Therefore, as a method for efficiently supporting the explosive increase in user data traffic in a cellular network, there is a need for a method of providing a compact cellular network by reducing the size of a cell or providing a service using a cellular network of a multi- Research has continued.

For example, Korean Patent Laid-Open Publication No. 10-2012-0138063 discloses a small cell base station access control method provided by a small cell base station. The method includes receiving a call connection request from a first terminal within a small cell base station coverage of a small cell base station with a capacity occupied by a plurality of second terminals operating within a small cell base station coverage, Selecting the access control target terminal from the first terminal and the plurality of second terminals based on the signal quality information of each of the first terminals that have transmitted the access control target terminal to the macro cell base station or another small cell base station Or moved.

However, there is always a possibility of communication degradation due to interference by other nearby communication entities in a communication environment in which a macro cell base station and a plurality of small cell base stations are mixed. Accordingly, there is a need for a method for allowing a terminal to reliably discovery small cell base stations for smooth communication with surrounding small cells.

Korean Patent Publication No. 10-2012-0138063 (December 24, 2012)

An object of the present invention is to provide a device for transmitting and receiving a discovery signal of an LTE small cell that transmits a discovery signal so that the terminal reliably recognizes a small cell base station.

It is another object of the present invention to provide an apparatus for transmitting and receiving a discovery signal of an LTE small cell that efficiently uses a discovery signal of a small cell base station and efficiently uses radio resources.

An apparatus for transmitting and receiving a discovery signal of a small cell according to an embodiment of the present invention includes an RF unit for transmitting and receiving a radio signal; And a small cell base station including a processor connected to the RF unit. The processor may be configured to transmit a discovery reference signal to the terminal.

Here, the small cell BS transmits the division information of the small cell base station using the CSI-RS RE configuration, the scrambling ID, the subframe offset, and the cover code to the terminal, the CSI-RS RE configuration, the subframe offset, Cell base station identification information, a small cell base station identification information, and a small cell base station identification information in combination of at least two of Scrambling ID, Subframe offset, and cover code, The base station identification information can be transmitted.

Also, the small cell base station transmits a discovery reference signal to the terminal at any one of 640 msec, 1,280 msec, 2,560 msec, 5,120 msec, 10,240 msec, and 20,480 msec, and the discovery reference signal has a value within 320 msec as an offset characteristic can do.

Here, the small cell base station can repeat the discovery reference signal every 20 x N (N = 1 to 1,000) [msec].

In addition, the terminal can receive only the number of less than half of the DL subframe among the discovery reference signals transmitted by the small cell base station.

Here, the small cell base station uses the CSI-RS as the discovery reference signal and transmits the discovery reference signal to the terminal using at least one of the CRS ports, or uses the CSI-RS as the discovery reference signal and uses all the antennas of the REs / PRB And a port to transmit the discovery reference signal to the terminal.

In addition, the small cell base station sets the discovery reference signal periodically with respect to the time domain and the frequency domain, consecutively sets the discovery reference signal with respect to the time domain, continuously sets the discovery reference signal with a constant interval to the frequency domain, and sets the discovery reference signal to any one of 1 msec to 1 sec Or the like.

Here, if the duration of the discovery reference signal is less than or equal to a reference value determined from 1 msec to 1 sec, the terminal can perform fast SCell on / off.

In addition, the small cell base station may use the CSI-RS as a discovery reference signal and transmit the discovery reference signal to the terminal using at least two DL subframes.

Herein, the small cell base station uses the DRX cycle differently when operating as a Pcell or as a Scell, and can preferentially use a Pcell when the DRX timing of the Pcell overlaps with the DRX timing of the Scell.

In addition, the small cell base station can transmit the information of the multicast or broadcast target terminal to the terminal along with the small cell base station information in the MBSFN subframe.

Here, the small-cell base station may transmit a discovery reference signal by fixing it to at least one sub-frame of sub-frames less than half of the DL sub-frame, or transmitting the discovery reference signal through any one of sub- And may transmit the included subframe information to the terminal.

In addition, when the small cell base station operates in FDD or TDD, the occupancy time of the discovery reference signal can be used within 10 subframes within one frame.

Here, the small cell base station may use at least one of a width, a period, an offset, frame information, a transmission level, an error correction signal, and constant interval information of subcarriers for setting a timing of a discovery reference signal.

Also, the UE can measure the RSSI of the discovery reference signal based on at least one of PDSCH RE, DRS RE, PDCCH RE, PBCH RE, PMCH RE, PHICH RE, and PCFICH RE.

Herein, the terminal calculates the reception quality of the reference signal by 1 / (A + DRSSI / RSRP / N) based on the DRSSI indicating the reception intensity of the discovery reference signal, the RSRP indicating the reception power of the discovery reference signal, And A may include any real number from 0 to 20.

In addition, the small cell base station can use the width of the base discovery reference signal within 10 subframes.

Herein, the small cell BS may be configured such that at least one of the period, the offset, the maximum measurable bandwidth, the MBSFN subframe setting of the neighboring cell, and the TDD downlink and uplink setting items of the neighboring cell are set to a discovery reference signal measurement timing configuration and can be set to have a restriction on a measurement gap.

The apparatus for transmitting and receiving a discovery signal of the LTE small cell according to the present invention has an advantage of transmitting a discovery signal so that the terminal reliably recognizes the small cell base station.

Alternatively, the discovery signal transmitting / receiving apparatus of the LTE small cell according to the present invention has an advantage that the discovery signal of the small cell base station can be efficiently set and wireless resources can be efficiently used.

1 is a block diagram of an LTE network according to an embodiment of the present invention.
2 is a configuration diagram of a dual connection when the first base station of FIG. 1 operates as a primary base station and the second base station operates independently as a secondary base station.
3 is a configuration diagram of a dual connection when the first base station of FIG. 1 operates as a primary base station, the second base station operates as a secondary base station, and data is separated and combined through a primary base station.
FIG. 4 is a detailed diagram illustrating a case where the secondary base station of FIGS. 2 and 3 is disconnected from the terminal.
FIG. 5 is a block diagram illustrating a method of allocating transmission power of a terminal to the main base station or the secondary base station of FIG. 2 and FIG. 3 in detail.
FIG. 6 is a configuration diagram illustrating a case where terminals are randomly accessed by the main base station or the secondary base station of FIG. 2 and FIG. 3;
FIG. 7 is a diagram illustrating a method for enhancing performance of a terminal in a dense area of a small-cell base station according to another embodiment of the present invention.
8 is a diagram illustrating that the small cell base station of FIG. 7 transmits a discovery reference signal.
FIG. 9 is a diagram illustrating that the small cell base station of FIG. 7 transmits a CSI-RS based discovery reference signal.
10 is a diagram illustrating that the small cell base station of FIG. 7 transmits small cell base station information to the terminal.
FIG. 11 is a diagram showing that the small cell base station of FIG. 7 transmits on / off information of the small cell base station to the terminal.
12 is a diagram showing an example in which the small cell base station of FIG. 7 transmits a discovery reference signal in accordance with FDD and TDD.
13 is a configuration diagram showing that the terminal receives the discovery reference signal transmitted by the small cell base station of FIG. 7 and measures the quality.
FIG. 14 is a diagram illustrating another example in which the small cell base station of FIG. 7 transmits a CSI-RS based discovery reference signal.
FIG. 15 is a configuration diagram showing that the terminal of FIG. 7 receives the discovery signal of the small cell base station with periodical control by DMTC setting.
16 is a block diagram illustrating a wireless communication system in which an embodiment of the present invention may be implemented.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood that the present invention is not intended to be limited to the specific embodiments but includes all changes, equivalents, and alternatives included in the spirit and scope of the present invention.

Hereinafter, an on / off information transmitting / receiving apparatus for an LTE small cell according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a configuration diagram of an LTE network according to an embodiment of the present invention, and FIGS. 2 to 6 are block diagrams for explaining FIG. 1 in detail.

Hereinafter, an on / off information transmitting / receiving apparatus for an LTE small cell according to an embodiment of the present invention will be described with reference to FIG. 1 to FIG.

First, referring to FIG. 1, an LTE network structure according to an embodiment of the present invention includes a BS and a terminal. In particular, when a macro cell and a D2D channel are separately allocated to each other, a new frequency can be allocated and used.

When the macrocell and the D2D channel are simultaneously allocated, inter-terminal communication can use at least one of the subchannel addition and the utilization of the physical channel being used in the macrocell. A channel management technique, and a duplexing method may be used.

In addition, synchronization between the terminals can be provided in the uplink, provided in the downlink, and used in at least one of uplink and downlink simultaneously.

The first terminal 110 and the third terminal 130 are located at the cellular link radius of the first base station 310 and the fourth terminal 240 and the fifth terminal 250 are located at the second base station 310. [ Lt; RTI ID = 0.0 > 320 < / RTI >

The third terminal 130 is located at a distance that allows D2D communication with the first terminal 110, the second terminal 120, and the fourth terminal 240. The D2D link between the third terminal 130 and the first terminal 110 is located in the same first base station 310 and the D2D link between the third terminal 130 and the fourth terminal 240 is located in another cellular radius, The D2D link of the third terminal 130 and the second terminal 120 includes a second terminal 120 that is not located in any cellular radius and a third terminal 130 that is located in a cellular radius of the first base station 310 have.

Here, the cellular link channel used between the first base station 310 and the third terminal 130 and the D2D link channel used by the third terminal 130 and the fourth terminal 240 may be separately allocated or allocated at the same time .

For example, when the same cellular link channel used between the first base station 310 and the third terminal 130 and the D2D link channel used by the third terminal 130 and the fourth terminal 240 use the same frequency, , PDCCH, PUSCH, and PUCCH may be separately allocated.

In particular, the first base station 310 can schedule a time slot allocation for transmission of a synchronization signal, a discovery signal, and a HARQ for the D2D link channel used by the third terminal 130 and the fourth terminal 240 have.

The synchronization signal transmitted by the first base station 310 may be used simultaneously with the information of the cellular link of the first base station 310 but may be synchronized with the synchronization signal used by the third terminal 130 and the fourth terminal 240, A discovery signal, and a time slot for transmission of HARQ can be scheduled so that a time slot does not overlap with a cell link channel used between the first base station 310 and the third terminal 130. [

Meanwhile, if the D2D link channel used by the third terminal 130 and the fourth terminal 240 uses a different frequency than the third terminal 130 and the third terminal 130, PDCCH, PUSCH and PUCCH OFDM symbols of the PDSCH, the PDCCH, the PUSCH and the PUCCH may be dedicated for scheduling by the third terminal 130 or the fourth terminal 240.

In addition, when performing the D2D communication between the third terminal 130 and the fourth terminal 240, interference which is influenced by the first base station 310 and the first terminal 110 is avoided and used. In particular, when performing the D2D communication between the third terminal 130 and the fourth terminal 240, the third terminal 130 transmits the synchronization signal received by the first base station 310 to the first base station 310, Link channel to the fourth terminal 240, to the fourth terminal 240 via the downlink channel used by the first base station 310 or to the uplink downlink channel used by the first base station 310, Channel to the fourth terminal 240 at the same time.

The following describes elements necessary for D2D data communication according to another embodiment.

2 is a configuration diagram of a dual connection when the first base station 310 of FIG. 1 operates as a primary base station 101 and the second base station 320 operates independently as a secondary base station 201. FIG.

The master eNB 101 and the secondary eNB 201, which are used for the dual connection, are individually connected to the core network.

Therefore, the main base station 101 and the secondary base station 201 are independent from each other, and in particular, all of the protocols are characterized in that the base station 101 and the secondary base station 201 are not separated and combined in communication with the two base stations.

3 illustrates a case where the first base station 310 of FIG. 1 operates as the primary base station 101 and the second base station 320 operates as the secondary base station 201 and the data is separated and combined through the primary base station 101 In this case, only the main base station is connected to the core network, and the main base station separates and combines data communicated in the core network.

4 is a configuration diagram showing details of a case where the secondary base station 201 of FIG. 2 and FIG. 3 is disconnected from the terminal 301. FIG.

That is, the on / off information transmitting / receiving apparatus of the LTE small cell includes a main base station 101, a main base station 101 for performing data communication with the terminal 301 by allocating radio resources to the terminal 301, And a terminal 301 for communicating data simultaneously with the main base station 101 and the sub-base station 201 and resetting the radio resource control when the link with the sub-base station 201 is lost do.

Herein, when the terminal 301 is not normally connected to the secondary base station 201, the terminal 301 informs the primary base station 101 of the connection state information, and the primary base station 101 informs the secondary base station 201 of the connection state information And informs the link state information between the base station 201 and the terminal 301.

Similarly, when there is an abnormality in connection with the main base station 101, the terminal 301 performs radio resource control resetting and reports the report to the secondary base station 201 so that the secondary base station 201 transmits a connection abnormality .

At this time, the communication between the main base station 101 and the secondary base station 201 may add information to a frame in the X2 interface or use a broadband network, or may communicate using a wireless backhaul if not connected by wire. Frame information may use a signaling system including a link state header, a link state, a base station ID, and a terminal ID indicating a link state of the main base station 101 and the secondary base station 201.

Therefore, when there is an abnormality in the connection between the main base station 101 and the secondary base station 201, the terminal 301 reports it to either the primary base station 101 or the secondary base station 201, The base station reporting the connection informs the base station that the connection is abnormal and the connection state with the terminal 301 can be checked.

On the other hand, when both the main base station 101 and the secondary base station 201 are abnormal in connection, the terminal 301 reestablishes the radio resource control so that it can communicate through the base station.

FIG. 5 is a detailed diagram showing a case where the transmission power of the mobile station 301 is allocated to the main base station 101 or the secondary base station 201 of FIG. 2 and FIG.

That is, the on / off information transmitting / receiving apparatus of the LTE small cell includes a main base station 101, a main base station 101 for performing data communication with the terminal 301 by allocating radio resources to the terminal 301, The transmission power upper limit value ratio of the primary base station 101 and the secondary base station 201 is calculated based on the statistical analysis of the power transmitted to the secondary base station 201 performing data communication and the primary base station 101 and the secondary base station 201 And a terminal 301 for setting the terminal.

The statistical analysis analyzes the transmission power ratio based on the average power transmitted by the terminal 301 to the main base station 101 and the secondary base station 201. The terminal 301 analyzes the transmission power ratio based on the average power transmitted from the primary base station 101 and the secondary base station 201 ) To report the upper limit of the transmit power.

That is, the mobile station 301 transmits the maximum power to the primary base station 101 and the secondary base station 201 based on the maximum power to be transmitted from the mobile station 301 and the average value of the transmission power to be sent to the primary base station 101 and the secondary base station 201 201).

For example, the ratio of power to be transmitted to the main base station 101 and the sub-base station 201 is set to 3: 1, 2: 2, 1: 3, and the like.

As another example, in distributing the power to be transmitted, it is very important to maintain the connectivity with the main base station 101 or to transmit the control signal to the main base station 101. Therefore, And can allocate the remaining power to transmit / receive data to / from the secondary base station 201.

As another example, the available power when transmitting data to the secondary base station 201 may change dynamically. That is, the Modulation and Coding Scheme (MCS) value to be used may vary depending on the available power even if the radio channel is not changed.

At this time, if the power allocation and the MCS value are changed at the same time, it may cause a data transmission error, so that the power allocation change and the MCS value change may not be performed at the same time.

Alternatively, in order not to cause a data transmission error when the power allocation and the MCS value are simultaneously changed, the reporting period of the CQI (Channel Quality Indicator) for changing the MCS, which is a feedback signal system, can be set not to occur simultaneously with the change of the power allocation.

On the other hand, if at least one of the margins of the maximum value of the terminal, the power ratio to be used, the maximum transmission power of each base station according to the power ratio, and the maximum power that can be transmitted by each base station, ) And the secondary base station (201).

6 is a configuration diagram showing details of a case where the terminal 301 is randomly accessed by the main base station 101 or the sub-base station 201 of FIG. 2 and FIG.

That is, the on / off information transmitting / receiving apparatus of the LTE small cell includes a main base station 101, a main base station 101 for performing data communication with the terminal 301 by allocating radio resources to the terminal 301, The main base station 101 and the subordinate base station 201 can perform either random access by triggering or self-random access without triggering to the main base station 101 and the subordinate base station 201, And a terminal 301 for transmitting the data to at least one of them.

Here, the triggering is performed by any one triggering command of PDCCH, MAC, and RRC, and the secondary base station 201 includes a base station that can access the primary base station 201 among the base stations that can operate as the secondary base station 201.

Here, the random access is transmitted in the form of a content preamble, an initial access, a radio resource control message, and a terminal ID.

That is, in the random access, the terminal 301 transmits the initial access, the establishment and re-establishment of the radio resource control to the main base station 101 or the secondary base station 201, It is possible to send random access to either the main base station 101 or the secondary base station 201 or to transmit the random access to the primary base station 101 or the secondary base station 201 at the same time.

At this time, random access may be transmitted through PDCCH, MAC, or radio resource control (RRC) triggering from the primary base station 101 or the secondary base station 201, but may also be transmitted through the terminal itself triggering.

In addition, random access can be transmitted using the remaining power excluding the power distributed in the uplink for random access.

Meanwhile, when the main base station 101 or the secondary base station 201 is newly turned on, peripheral terminals including the terminal 301 perform random access at the same time, thereby causing an error in data communication due to random access.

Therefore, when the main base station 101 or the sub-base station 201 is newly turned on to reduce the influence, the terminal 301 can perform random access using a random time of about 10 seconds. Here, 10 seconds is a maximum random access time that can be varied according to the number of terminals and the number of base stations, and the maximum random access time can be any value within 1 second to 60 seconds depending on the environment.

The mobile station 301 can use multiple antennas to identify the location of transmission from the main base station 101 or the secondary base station 201 and perform random access in the direction of the primary base station 101 or the secondary base station 201 Interference effects can be minimized.

Alternatively, when the positions of the main base station 101 and the secondary base station 201 are not accurate, the terminal 301 may sweep 360 degrees and perform random access.

FIG. 7 is a block diagram illustrating a method for enhancing performance of a terminal in a dense area of a small-cell base station according to another embodiment of the present invention, and FIG. 8 is a block diagram for explaining FIG. 7 in detail.

Hereinafter, an on / off information transmitting / receiving apparatus for an LTE small cell according to another embodiment of the present invention will be described with reference to FIGS.

Referring to FIG. 7, a method for enhancing performance of a UE according to another embodiment of the present invention includes a cellular interference cancellation technique for reducing cellular interference occurring between a Node B 112 and a UE 312, A TXOP (Transmit Opportunity) technique for scheduling a transmission opportunity between the small cell base station 212 and the terminal 322; a frame relocation technique for efficiently using a frame between the small cell base station 212 and the terminal 322; An SDM (Spatial Domain Multiplexing) technique that improves the quality of service provided to the terminal 322 by spatial antenna arrangement between the small cell base station 220 and the terminal 322, An efficient handover technique for efficiently switching when the terminal 322 in the service area of the small cell base station 212 enters the service area of the small cell base station 220 and switches the connection of the small cell base station 220 An efficient duplex technique that more efficiently uses the duplex scheme between the small cell base station 220 and the mobile station 330 and an efficient duplex technique that uses the multiple antennas between the small cell base station 220 and the mobile station 342, The MS 342 in the radius of the small cell base station 220 transmits the information of the small cell base station 220 to the terminal 352 that is not in the service radius of the small cell base station 220 in the MIMO (Multiple Input Multiple Output) a D2D (Device to Device) technology for directly communicating between the terminal 342 and the terminal 362, a relay technology for relaying the UL and DL bandwidth efficiently between the small cell base station 232 and the terminal 362 an asymmetric technique, a bandwidth technique for adjusting a bandwidth between the terminal 362 and the small cell base station 232, and a multicast technique for transmitting the same data to a common user in the small cell base station 232.

The small cell base station 220 transmits a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), and a Cell Specific Reference Signal (CRS) CSI-RS (Channel State Indicator? Reference Signal), and PRS.

The PSS, PSS / SSS, CRS, CSI-RS, and PRS signals can be used for time synchronization, frequency synchronization, Cell / TP (Transmission Points) identification, and RSRP (Reference Signal Received Power) measurements. CSI-RS is not used for time synchronization but RSSI is used for measurement of RSRQ (reference signal received power) with symbols including a discovery signal.

The measurement of RSRP and RSRQ can be considered in muting and various cases in the transmitter, and interference cancellation in the receiver.

The UE can detect multiple cells through a DRS configuration for one frequency, and can also perform CRS-based RSRP measurements and CSI-RS-based RSRP measurements.

The UE may set the DRS measurement time per frequency. At this time, the setting of the DRS measurement time refers to the setting of the time at which the UE performs the cell detection or the RRM measurement based on the DRS. Here, the DRS measurement time setting includes the minimum period, the offset relative to the serving cell, and the maximum possible measurement width.

DRS can be used as a kind of rel-8 PSS / SSS and can be configured with various CSI-RS settings. At this time, the various CSI-RS settings may or may not be in the same subframe and may be different independent scrambles.

Meanwhile, the CRS used in the DRS can be transmitted in the same frame as the PSS / SSS and not transmitted continuously with the CSI-RS.

In addition, the SSS used in the DRS can be fixed within 5msec or the offset between the CSI-RE settings can be varied, and the DRS can be continuously configured within 5 sectors.

The scramble ID of the PSS / SSS / CRS used in the DRS is different from the PCID or the scramble ID of the CSI-RS is the PCID. Further, the TP identification can be represented by a CSI-RS RE setting, a scramble ID, a subframe offset, a cover code, or a combination thereof.

The DRS may be transmitted in the DL subframe or in the DwPTS region of the subframe. Also, the DRS can be transmitted in the MBSFN subframe, and the DRS level can be designed in consideration of the trade-off between the synchronization level, the number of reuses, and the surrounding interference such as the intra-base station planning and total received power.

8 is a diagram illustrating that the small cell base station of FIG. 7 transmits a discovery reference signal.

At this time, the discovery signal transmitting and receiving apparatus of the LTE small cell includes a small cell base station 220 for transmitting a discovery reference signal to the terminal 330.

Herein, the small cell base station 220 transmits the identification information of the small cell base station using the CSI-RS RE configuration, the scrambling ID, the subframe offset, and the cover code to the terminal 330, At least two of the division information of the small cell base station is transmitted in combination of at least two of the subframe offset and the cover code, and the division information of the small cell base station is transmitted in combination of at least two of the scrambling ID, the subframe offset, It is possible to transmit the division information of the small cell base station by using one.

A physical cell ID (PCID), a virtual cell ID (VICD), a CSI-RS RE, and so forth can be transmitted as a method of transmitting a signal to the terminal 330 for identification of the small- Setting CSI-RS subframe setting and the like can be used. The PCID is an ID for identifying the small cell base station 220. The terminal 330 can identify the PCID by distinguishing the PSS / SSS / CRS.

The VCID is an ID for identifying the virtual small cell base station 220 and can be known by a scramble ID used for CSI-RS transmission. The CSI-RE configuration refers to the setting of the allocation method of the RE (Resource Element) of the CSI-RS on the OFDM symbol, and the CSI-RS subframe offset setting refers to the offset in which the CSI- RS is located after the SSS signal on the subframe set as the DRS region Lt; / RTI >

The small cell base station 220 transmits a discovery reference signal to the terminal 330 at any one of 640 msec, 1,280 msec, 2,560 msec, 5,120 msec, 10,240 msec, and 20,480 msec, and the discovery reference signal is transmitted within 320 msec One value can be an offset property.

Here, the small cell base station 220 may repeat the discovery reference signal every 20 x N (N = 1 to 1,000) [msec].

Also, the terminal 330 can receive only the number of less than half of the DL subframe among the discovery reference signals transmitted by the small cell base station 220.

Here, the small cell base station 220 uses the CSI-RS as the discovery reference signal and transmits the discovery reference signal to the terminal 330 using at least one of the CRS ports, or uses the CSI-RS as the discovery reference signal And transmits the discovery reference signal to the terminal 330 using at least one of all the antenna ports of the REs / PRB.

In addition, the small cell base station 220 periodically sets the discovery reference signal for the time domain and the frequency domain, continuously sets the discovery reference signal for the time domain, sets the discovery reference signal continuously at a constant interval to the frequency domain, And the setting period is set to at least one of.

Here, if the duration of the discovery reference signal is less than or equal to a reference value determined from 1 msec to 1 sec, the terminal 330 can perform fast SCell on / off.

In addition, the small cell base station 220 may transmit a discovery reference signal for discovery to the terminal 330. The discovery reference signal may be a Downlink Pilot Time Slot (DLPTS) of a DL frame or a subframe, It can be transmitted through the area.

In a discovery reference signal-based measurement, the discovery reference signal may be transmitted along with the DL sync signal channel, and may be repeated in any one of 20xN (N = 1 to 1,000) cycles.

Here, the DRS measurement timing configuration (DMTC) indicates the time that the UE 330 can perform the cell search and the RRM (radio resource measurement) based on the DRS. That is, the DMTC- A plurality of cells can be detected.

Thus, the terminal 330 may expect the location of the DRS from the DMTC and the DMTC may include at least a period, an offset from the serving cell timing, and a usage width, It can be set to at least 40 ms, 80 ms, or 160 ms for measurement.

The terminal 330 receiving the discovery signal can receive only the number of less than half of the DL subframe among the discovery reference signals transmitted by the small cell base station 220 in order to save the battery.

That is, the duration of DRS occasion of the discovery reference signal can be determined by a number equal to or less than half of the DL subframe. For example, in case of FDD, subframes 1 to 5 may be set, or in case of TDD, subframes 2 to 4 may be set. Since there is no DwPTS or UpPTS relative to TDD, the FDD can allocate a much larger occupancy period of the discovery reference signal than the TDD because there is room in the frame. On the other hand, TDD can be set to use only 2 ~ 4 subframes without using one symbol before and after the frame used by FDD because the frame has a relatively small margin due to use of DwPTS or UpPTS in addition to UL and DL.

FIG. 9 is a diagram illustrating that the small cell base station of FIG. 7 transmits a CSI-RS based discovery reference signal.

Here, the small cell base station 220 uses the CSI-RS as a discovery reference signal and transmits a discovery reference signal to the terminal 330 using at least two DL subframes (for example, subframes 1 and 6) .

Here, the small cell base station 220 may use the DRX cycle differently when operating as a Pcell or as a Scell, and may preferentially use a Pcell when DRcell timing of a Pcell and a Scell overlap.

10 is a diagram illustrating that the small cell base station of FIG. 7 transmits small cell base station information to the terminal.

Here, the small cell base station 220 may transmit information of the multicast or broadcast target terminal 330 to the terminal 330 together with the small cell base station 220 information in the MBSFN subframe.

Here, the small cell base station 220 transmits the discovery reference signal by fixing it to at least one sub-frame of sub-frames less than half of the DL sub-frame, or transmits the discovery reference signal through one of sub- And transmits the subframe information including the signal to the terminal 330.

That is, the terminal 330 receiving the discovery signal can receive the discovery signal at least to save battery power. Therefore, the small cell base station 220 may send a discovery signal to five or less half of the DL subframe, or may include the information of the subframe including the discovery signal in five or less half of the DL subframe .

In addition, when CSI-RS is used as a discovery signal, CSI-RS can be transmitted using at least two DL sub-frames in order to perform discovery quickly.

FIG. 11 is a diagram showing that the small cell base station of FIG. 7 transmits on / off information of the small cell base station to the terminal.

Here, the small cell base station 220 transmits the on / off state of the small cell base station 220 through the PDCCH, PHICH, or PCFICH channel including the DCI message when the small cell base station 220 is used as a secondary base station, , PDSCH, PBCH, or PMCH to the terminal 330 through the channel.

Here, the small cell base station 220 may transmit a broadcast message through a PDCCH, a PHICH, or a PCFICH including a DCI message, or may transmit the broadcast message to a terminal 330 through a channel such as a PDSCH, a PBCH, or a PMCH.

That is, the DCI (Downlink Control Information) is information for transmitting the scheduler and the hybrid ARQ protocol. The DCI is transmitted through a Physical Downlink Control Channel (PDCCH) as a downlink control channel, a PHICH (Physical Hybrid ARQ Indicator Channel) as a downlink hybrid ARQ dedicated channel, and a Physical Control Format Indicator Channel (PCFICH) do.

Meanwhile, the Enhanced PDCCH (Enhanced PDCCH) is a channel having an additional function for the PDCCH, and the PDSCH is a channel for transmitting data or transmitting paging information to one UE 330. A PBCH (Physical Broadcast Channel) and a PMCH Channel are broadcast channels and multicast channels, respectively.

12 is a diagram showing an example in which the small cell base station of FIG. 7 transmits a discovery reference signal in accordance with FDD and TDD.

Here, when the small cell base station 220 operates as FDD or TDD, the occupancy time of the discovery reference signal can be used within 10 subframes within one frame.

That is, the small cell base station 220 can transmit the discovery reference signal through at least one of the subframes of one frame defined by 10 subframes.

For example, in case of FDD, it can be set to at least one of subframes 1 to 5, or in case of TDD, at least one of subframes 2 to 4 can be set. Since FDD has relatively no DwPTS or UpPTS compared to TDD, there is room in the frame, and it is possible to allocate much occupancy period of the discovery reference signal compared to TDD. On the other hand, TDD has a relatively small frame margin due to the use of DwPTS or UpPTS in addition to UL and DL, so that only two or four subframes are used for transmission of the discovery reference signal without using one symbol before and after the frame used by FDD It is possible.

13 is a configuration diagram showing that the terminal receives the discovery reference signal transmitted by the small cell base station of FIG. 7 and measures the quality.

Here, the small cell base station 220 may use at least one of a width, a period, an offset, frame information, a transmission level, an error correction signal, and constant interval information of subcarriers for setting a timing of a discovery reference signal.

Also, the UE 330 may measure the RSSI of the discovery reference signal based on at least one of PDSCH RE, DRS RE, PDCCH RE, PBCH RE, PMCH RE, PHICH RE, and PCFICH RE.

A physical downlink shared channel (PDSCH) is a channel for transmitting data or transmitting paging information to one terminal 330, and a PDCCH (Physical Downlink Control Channel) And a scheduling decision for the PDSCH as a downlink control channel.

In addition, the Physical Hybrid ARQ Indicator Channel (PHICH) is a downlink hybrid ARQ dedicated channel, and the Physical Control Format Indicator Channel (PCFICH) is a channel for transmitting decoding information of the PDCCH. The PBCH and the Physical Multicast Channel (PMCH) Represents a broadcast channel and a multicast channel, respectively.

Meanwhile, the terminal 330 receives the reference signal reception quality of 1 / (A + DRSSI / RSRP / RSRP) based on DRSSI indicating the reception intensity of the discovery reference signal, RSRP indicating the reception power of the discovery reference signal, N), and A may include any real number from 0 to 20. [

In this case, A may vary according to various cases including the number of CRS ports and the type of RSRQ. In particular, when A = 0, the reception quality of the reference signal can be simply expressed as N * RSRP / DRSSI.

DRSSI refers to the total power of the OFDM symbol in the downstream part of the measurement subframe including the DRS, and RSRP denotes the power of the DRS among the OFDM symbols measuring the DRSSI. The larger the relative power of the OFDM symbols including the DRS signal, the greater the RSRQ.

Also, N is a specific window, which means the number of RBs (resource blocks) in the DRSSI measurement band. In other words, RSRQ can also be expressed as RSRP / (DRSSI / N), where the demodulation term represents the received power per RB in an OFDM symbol included in the DRS.

Also, RSRQ means the power ratio of DRS to RB per OFD symbol in the OFDM symbol including DRS. Here, among RSRQs, DRS related quality can be represented by DRSRQ (DRS received quality), and RSRP related to DRS can be expressed by DRSRP (DRS received power).

FIG. 14 is a diagram illustrating another example in which the small cell base station of FIG. 7 transmits a CSI-RS based discovery reference signal.

Here, the small cell base station 220 can use the width of the discovery reference signal within 10 subframes.

For example, in case of FDD, subframes 1 to 5 may be set, or in case of TDD, subframes 2 to 4 may be set. Since FDD has relatively no DwPTS or UpPTS compared to TDD, there is room in the frame, and it is possible to allocate much occupancy period of the discovery reference signal compared to TDD. On the other hand, TDD has a relatively small frame margin due to the use of DwPTS or UpPTS in addition to UL and DL, so there is a method of using only 2 to 4 subframes without using one symbol before and after the frame used by FDD.

FIG. 15 is a configuration diagram showing that the terminal of FIG. 7 receives the discovery signal of the small cell base station with periodical control by DMTC setting.

At this time, the small cell base station 220 determines at least one of a period, an offset, a maximum measurable bandwidth, an MBSFN subframe setting of a neighboring cell, and a TDD downlink and uplink setting item of a neighbor cell, ) Can be set to have a constraint on the measurement gap.

That is, in the terminal setting in which the measurement gap can be set, a limitation is imposed on the DMTC setting, and every DMTC per frequency can be aligned to a part of the measurement gap.

Terminal 330 may expect that there may be a discovery reference signal at each DMTC time.

If the DMTC is set for the frequency belonging to the cell-ID to which the DMTC is applied, the terminal 330 may assume that another cell not belonging to the cell-ID transmits the existing signal, not the DMTC.

In addition, if no cell-ID is provided, the terminal 330 may apply the DMTC setting to all cells for that frequency.

On the other hand, the limited measurement of the discovery setting can be applied not only to the DMTC setting but also to the limited RRM measurement.

16 is a block diagram illustrating a wireless communication system in which an embodiment of the present invention may be implemented.

The wireless communication system according to FIG. 16 may include at least one base station 800 and at least one terminal 900.

The base station 800 may include a memory 810, a processor 820, and an RF unit 830. The memory 810 may be coupled to the processor 820 to store various information and instructions for executing the processor 820. [ The RF unit 830 may be coupled to the processor 820 to transmit and receive wireless signals to and from an external entity. The processor 820 may execute the operations of the base station in the above-described embodiments. Specifically, the operation of the base stations 100, 101, 112, 200, 201, 212, 220, 232, 310, 320, etc. in the above embodiments may be implemented by the processor 820.

The terminal 900 may include a memory 910, a processor 920, and an RF unit 930. The memory 910 may be coupled to the processor 920 to store various information and instructions for executing the processor 920. [ The RF unit 930 may be coupled to the processor 920 to transmit and receive wireless signals to and from external entities. The processor 920 may execute the operations of the terminal in the above-described embodiments. Specifically, the operation of the terminals 110, 120, 130, 240, 250, 300, 312, 322, 330, 342, 352, 362 etc. in the above embodiments may be implemented by the processor 920 .

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being connected or connected to another element, it may be directly connected or connected to the other element, although other elements may be present in between. On the other hand, when it is mentioned that an element is directly connected or directly connected to another element, it should be understood that no other element exists in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the term " comprise " or " comprising ", etc. is intended to specify that there are stated features, numbers, steps, operations, elements, parts or combinations thereof, , But do not preclude the presence or addition of one or more other features, elements, components, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, these functions may be stored or transmitted as one or more instructions or code on a computer readable medium. Computer-readable media includes both communication media and computer storage media including any medium that facilitates transfer of a computer program from one place to another.

In a hardware implementation, the functions described herein may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays A processor, a controller, a microcontroller, a microprocessor, other electronic units designed to perform the functions described herein, or a combination thereof.

In a software implementation, the functions described herein may be implemented in software code. The software codes may be stored in memory units and executed by processors. The memory unit may be implemented within the processor and external to the processor, in which case the memory unit may be communicatively coupled to the processor by various means as is known.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

Claims (18)

An apparatus for transmitting and receiving a discovery signal of a small cell,
An RF unit for transmitting and receiving a radio signal; And
And a small cell base station including a processor connected to the RF unit,
Wherein the processor is configured to transmit a discovery reference signal to the terminal. The method according to claim 1,
The small-
A combination of at least two of a CSI-RS RE configuration, a subframe offset, and a cover code is transmitted to the terminal by using any one of a CSI-RS RE configuration, a scrambling ID, a subframe offset, Cell base station identification information using at least one of transmitting the identification information of the small cell base station and transmitting the identification information of the small cell base station by combining at least two of the scrambling ID, the subframe offset, and the cover code. And transmits the discovery signal to the small cell. The method according to claim 1,
The small-
The discovery reference signal is transmitted to the terminal at any one of a period of 640 msec, 1,280 msec, 2,560 msec, 5,120 msec, 10,240 msec, and 20,480 msec, and the discovery reference signal has a value within 320 msec as an offset characteristic And a small cell for transmitting and receiving the discovery signal. The method according to claim 1,
The small-
And the discovery reference signal is repeated every 20 x N (N = 1 to 1,000) [msec]. The method according to claim 1,
The terminal,
Wherein the small cell base station receives only the number of less than half of the DL subframe among the discovery reference signals transmitted by the small cell base station. The method according to claim 1,
The small-
The CSI-RS is used as the discovery reference signal, the CSI-RS is used as a discovery reference signal, and at least one of all antenna ports of the REs / PRB is transmitted using the at least one of the CRS ports and the discovery reference signal. And transmits the discovery reference signal to the terminal using one of the plurality of discovery reference signals. The method according to claim 1,
The small-
At least one of setting the discovery reference signal periodically for the time domain and the frequency domain, continuously setting for the time domain, continuously setting the frequency domain at a constant interval, and setting the discovery reference signal at any one of 1 msec to 1 sec The small cell is set by using the set value. The method according to claim 1,
The terminal,
And performs fast SCell on / off when the duration of the discovery reference signal is less than or equal to a reference value determined from 1 msec to 1 sec. The method according to claim 1,
The small-
Wherein the CSI-RS is used as the discovery reference signal, and the at least two DL subframes are used to transmit the discovery reference signal to the terminal. The method according to claim 1,
The small-
Wherein the DRX cycle is differently used in case of operating as a Pcell or as a Scell, and when the DRX timing of a Pcell is overlapped with a DRV timing of the Scell, the Pcell is preferentially used. The method according to claim 1,
The small-
And transmits the information of the terminal to be multicast or broadcast to the terminal together with the small cell base station information in the MBSFN subframe. The method according to claim 1,
The small-
A subframe including at least one subframe of less than half of the DL subframe and transmitting the discovery reference signal or at least one subframe of less than half of the DL subframe, And transmits the discovery signal to the small cell. The method according to claim 1,
Wherein the small cell base station uses the occupancy time of the discovery reference signal within 10 subframes within one frame when the small cell base station operates in FDD or TDD. The method according to claim 1,
Wherein the small cell base station uses at least one of a width, a period, an offset, a frame information, a transmission level, an error correction signal, and a constant interval information of subcarriers for setting a timing of the discovery reference signal. Apparatus for transmitting and receiving a discovery signal. The method according to claim 1,
Wherein the UE measures the RSSI of the discovery reference signal based on at least one of PDSCH RE, DRS RE, PDCCH RE, PBCH RE, PMCH RE, PHICH RE, and PCFICH RE. Lt; / RTI > The method according to claim 1,
The terminal may calculate a reception quality of the reference signal by 1 / (A + DRSSI / RSRP / N) based on DRSSI representing the reception strength of the discovery reference signal, RSRP representing the reception power of the discovery reference signal, ), And A represents any real number from 0 to 20. 13. The apparatus for transmitting and receiving a discovery signal of a small cell according to claim 12, The method according to claim 1,
Wherein the small cell base station uses the width of the discovery reference signal within 10 subframes. The method according to claim 1,
At least one of the period, the offset, the maximum measurable bandwidth, the MBSFN subframe setting of the neighboring cell, and the TDD downlink and uplink setting items of the neighboring cell may be a discovery reference signal measurement timing configuration (DMTC) measurement gap and the measurement gap is set to have a constraint on the discovery signal of the small cell.

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