KR20160082924A - Method and apparatus for transmitting pilot in multi-antenna communication system, and method and apparatus for allocating pilot in multi-antenna communication system - Google Patents

Abstract

Provided is a method for transmitting a pilot signal by a base station in a multi-antenna communication system. The base station includes part of a plurality of pilot signals, divided by at least one of a time domain symbol, a subcarrier, and an orthogonal code, in a first set to which a first random number is applied. The base station uses the same resources as resource used by the first set, and includes the remainder of the pilot signals, except for pilot signals, included in the first set, of the pilot signals, in a second set, to which a second random number different from the first random number is applied. The base station transmits at least one of the pilot signals included in the first and second sets.

Description

METHOD AND APPARATUS FOR TRANSMITTING PILOT IN MULTI-ANTENNA COMMUNICATION SYSTEM, AND METHOD AND APPARATUS FOR ALLOCATING A PILOT IN MULTI-ANTENNA COMMUNICATION SYSTEM, AND METHOD AND APPARATUS FOR ALLOCATING A PILOT IN A MULTI- ANTENNA COMMUNICATION SYSTEM}

The present invention relates to a method and apparatus for transmitting pilots in a multi-antenna communication system.

The present invention also relates to a method and apparatus for allocating pilots in a multi-antenna communication system.

Multiple input multiple output (MIMO) techniques are widely used to increase communication capacity in communication systems. A system according to the LTE (long term evolution) -A (Advanced) standard of the cellular mobile communication system can transmit 8 streams using 8 antenna ports.

In the eight antenna ports, the beamformed data is transmitted with sharing orthogonal frequency division multiplexing (OFDM) symbols and subcarrier resources, and the pilot signal is also transmitted through the same beamforming as the data. At this time, the pilot signal (or pilot) is transmitted together with the data only when the data is transmitted.

On the other hand, due to the recent rapid increase in wireless traffic, the standardization organizations such as the 3GPP (3 ^rd generation partnership project) and the mobile communication industry have developed a millimeter wave (mmWave) having an available frequency bandwidth wider than that used in conventional cellular mobile communication ) Bands are being studied in mobile communication applications.

The use of high frequencies such as millimeter waves enables reduction of the antenna size, and reduction of the antenna size allows the base station to mount a larger number of antennas than before.

The base station can transmit a plurality of fixed beams or adaptive beams in a sector through a plurality of antennas. These multiple antennas also enable the operation of a 3D (3-dimensinal) beamforming base station system.

On the other hand, a base station needs a plurality of pilots in order to transmit traffic data through a plurality of beams. However, allocating the pilots as independent as the increased beam acts as an overhead to the whole system, thereby decreasing the communication capacity. Therefore, pilot design and operation are important.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for configuring (or allocating) pilots in a communication system requiring a plurality of pilots because a plurality of data streams are transmitted through spatial multiplexing using a plurality of antennas, A method and apparatus for transmitting a pilot.

Another object of the present invention is to provide a method and apparatus for allocating pilots so that inter-pilot interference is minimized according to the number of streams when multiplexing a plurality of streams.

According to an embodiment of the present invention, a method is provided in which a base station transmits a pilot signal in a multi-antenna communication system. A method of transmitting a pilot signal of a base station includes transmitting a pilot signal divided through at least one of a time domain symbol, a subcarrier, and an orthogonal code among a plurality of pilot signals to a first Incorporating into the set; A second set of the plurality of pilot signals using the same resources as the resources used by the first set and applying a second random number different from the first random number, Including a pilot signal; And transmitting at least one of the pilot signals belonging to the first set and the second set.

The first pilot signal and the second pilot signal, which are distinguished through the first orthogonal code among the pilot signals belonging to the second set, are distinguished through the first orthogonal code among the pilot signals belonging to the first set The same resources as the third pilot signal and the fourth pilot signal can be used.

The multi-antenna communication system may transmit multiple beams in the millimeter waveband.

The first orthogonal code may be a Walsh code.

The time domain symbol may be an orthogonal frequency division multiplexing (OFDM) symbol.

Each of the first random number and the second random number may be a PN (pseudo noise) sequence.

The transmitting may include simultaneously transmitting at least one of at least one of the pilot signals belonging to the first set and the pilot signal belonging to the second set through a plurality of beams.

Also according to another embodiment of the present invention, a method is provided for a base station to allocate a pilot in a multi-antenna communication system. The method comprising: setting a first pilot set and a second pilot set using the same resources and distinguished through different random numbers; And assigning, to the data stream to be multiplexed, a pilot belonging to the first pilot set prior to a pilot belonging to the second pilot set.

The step of assigning, to the data stream to be multiplexed, a pilot belonging to the first pilot set more preferentially than a pilot belonging to the second pilot set includes: determining the number of data streams to be multiplexed; Comparing the determined number with the number of pilots belonging to the first pilot set; And allocating the determined number of pilots among the pilots belonging to the first pilot set to the data streams to be multiplexed when the determined number is equal to or less than the number of pilots belonging to the first pilot set.

Wherein the step of assigning, to the data stream to be multiplexed, a pilot belonging to the first pilot set prior to a pilot belonging to the second pilot set, when the determined number is larger than the number of pilots belonging to the first pilot set, Assigning a pilot belonging to a first pilot set to a portion of the data streams to be multiplexed; And allocating, to the remainder of the data streams to be multiplexed, a pilot corresponding to the number of pilots belonging to the first pilot set minus the number of pilots belonging to the first pilot set among the pilots belonging to the second pilot set.

Wherein the determining the number of data streams to multiplex comprises: receiving channel state information for a plurality of beams from the terminal; Calculating interference between the plurality of beams based on the channel state information; And determining the number of data streams to be multiplexed based on the interference between the multiple beams.

The step of receiving channel state information for the plurality of beams may include transmitting beam status information (BSI) -RS (reference signal) through the plurality of beams; And receiving the channel state information including a channel quality indicator (CQI) measured based on the BSI-RS from a terminal receiving the BSI-RS.

The base station can operate a plurality of distributed antennas.

Further, according to another embodiment of the present invention, a method is provided for a base station to allocate a pilot in a multi-antenna communication system. The method comprising: setting a first pilot set and a second pilot set using the same resources and distinguished through different random numbers; Allocating, to the plurality of beams, a pilot belonging to the first pilot set and a pilot belonging to the second pilot set; Determining a pilot allocated to a beam for a data stream to be multiplexed among the plurality of beams; And allocating the determined pilot among the pilots belonging to the first pilot set and the second pilot set to the data stream to be multiplexed.

According to an embodiment of the present invention, pilot overhead can be reduced by allocating pilots using a plurality of pilot sets using the same resources in a multi-antenna communication system in which a plurality of pilots are required.

In addition, according to the embodiment of the present invention, it is possible to prevent deterioration of channel estimation performance of a pilot by designating allocation order of pilots so that inter-pilot interference is minimized when multiple data streams are multiplexed.

FIG. 1 is a diagram illustrating a pilot divided through OFDM symbols, subcarriers, and orthogonal codes.
2 is a diagram illustrating a pilot configuration method according to an embodiment of the present invention.
3 is a diagram illustrating a mobile communication base station operating in the millimeter waveband and transmitting a plurality of fixed beams, in accordance with an embodiment of the present invention.
4 is a diagram showing inter-beam interference caused by a reflector when a base station transmits multiple beams in a millimeter wave band.
5 is a diagram illustrating a method of allocating pilots in a spatial multiplexing transmission according to an embodiment of the present invention.
6 is a diagram illustrating a method of allocating pilots in a spatial multiplexing transmission according to another embodiment of the present invention.
7 is a diagram illustrating a base station operating in a millimeter wave band and operating a distributed antenna according to an embodiment of the present invention.
8 is a diagram illustrating a base station according to an embodiment of the present invention.
9 is a diagram illustrating a terminal according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, a terminal may be referred to as a mobile terminal, a mobile station, an advanced mobile station, a high reliability mobile station, a subscriber station, A mobile subscriber station, a mobile subscriber station, an access terminal, a user equipment, and the like, and may also be referred to as a terminal, a mobile terminal, a mobile station, an advanced mobile station, An access terminal, a user equipment, and the like.

In addition, a base station (BS) includes an advanced base station, a high reliability base station, a node B, an evolved node B (eNodeB) an access point, a radio access station, a base transceiver station, a mobile multihop relay (MMR) -BS, a relay station serving as a base station, a high reliability repeater BS, Node B, eNodeB, access point, radio access station, transmitting / receiving base station, MMR-BS, and so on, may be referred to as a high reliability relay station, a repeater, A repeater, a high reliability repeater, a repeater, a macro base station, a small base station, and the like.

FIG. 1 is a diagram illustrating a pilot divided through OFDM symbols, subcarriers, and orthogonal codes.

One subframe includes an even number of time slots (hereinafter referred to as 'slot 0') and an odd number of time slots after slot 0 (hereinafter referred to as 'slot 1'). Each of slot 0 and slot 1 includes 7 OFDM symbols on the time axis and 12 subcarriers (0 to 11) on the frequency axis. That is, 84 (= 7x12) REs (resource elements) exist in each of the slot 0 and the slot 1. In this specification, seven OFDM symbols included in slot 0 are referred to as OFDM symbols 0 to 6, and seven OFDM symbols included in slot 1 are referred to as OFDM symbols 7 to 13.

When a base station having multiple antennas desires to simultaneously transmit data to a plurality of terminals, a plurality of pilots (or pilot signals) are required. Since the pilot serves as a reference for demodulating the data signal, the demodulation performance largely depends on noise or interference.

An OFDM symbol and a subcarrier resource are allocated to each pilot so that a plurality of pilots can be distinguished. For example, as illustrated in FIG. 1, the pilot corresponding to antenna port # 7 or # 8 and the pilot corresponding to antenna port # 9 or antenna port # 10 use different resources. That is, the pilot corresponding to the antenna port # 7 or # 8 and the pilot corresponding to the antenna port # 9 or # 10 can be divided through the subcarrier resource.

On the other hand, pilots sharing the same resource are distinguished by orthogonal codes. For example, as illustrated in FIG. 1, the pilot corresponding to the antenna port # 7 and the pilot corresponding to the antenna port # 8 use the same resources. Pilot corresponding to antenna port # 7 and pilot corresponding to antenna port # 8 can be distinguished through an orthogonal code. The pilot corresponding to the antenna port 9 and the pilot corresponding to the antenna port 10 use the same resources. Pilot corresponding to antenna port # 9 and pilot corresponding to antenna port # 10 can be distinguished through an orthogonal code. A plurality of pilot signals for spatial multiplexing are generated by multiplying the pilot sequence by the orthogonal codes described above. The pilot sequence uses a random number to reduce the degradation of the channel estimation performance due to interference, for example, a PN (pseudo noise) sequence can be used.

2 is a diagram illustrating a pilot configuration method according to an embodiment of the present invention.

The base station can configure a plurality of pilots into a plurality of pilot sets. Specifically, FIG. 2 illustrates a case where a total of 16 pilots and 16 pilots are composed of two pilot sets S1 and S2.

Each of pilot set S1 and pilot set S2 includes at least one pilot. Specifically, FIG. 2 illustrates a case where there are eight pilots belonging to the pilot set S1 and eight pilots belonging to the pilot set S2 (nos. 9 to 16). For example, the pilot belonging to the pilot set S1, S2 may be DM (demodulation) -RS (reference signal), which is a demodulation reference signal, or may be another reference signal.

The pilots (1 to 8) belonging to the pilot set (S1) are distinguished from each other by different positions of the OFDM symbols and the subcarriers, or pilots (1 to 4, or 5 to 8) And may be distinguished by different orthogonal codes (e.g., Walsh codes). Specifically, the pilots (# 1 to # 4) belonging to the pilot set S1 use the same resources and can be distinguished through different orthogonal codes. Similarly, pilots (# 5 through # 8) belonging to the pilot set S1 use the same resources and can be distinguished through different orthogonal codes. The pilots (Nos. 1 to 4) belonging to the pilot set S1 and the pilots (Nos. 5 to 8) belonging to the pilot set S1 can be distinguished through OFDM symbols and subcarriers.

Pilots (Nos. 9 to 16) belonging to the pilot set S2 are distinguished from each other by different positions of OFDM symbols and subcarriers, or pilots (Nos. 9 to 12, or 13 to 16) And can be distinguished by different orthogonal codes. On the other hand, the pilots (Nos. 9 to 16) belonging to the pilot set S2 are located in the same OFDM symbols and the same subcarriers as the pilots (1 to 8) belonging to the pilot set S1 and use the same orthogonal code . Specifically, the pilots (Nos. 9 to 12) belonging to the pilot set S2 are located in the same OFDM symbol and the same subcarriers as the pilots (1 to 4) belonging to the pilot set S1, Use the same orthogonal code as the pilot (# 1 - # 4) to which it belongs. Likewise, the pilots (13 to 16) belonging to the pilot set (S2) are located in the same OFDM symbol and the same subcarriers as the pilots (5 to 8) belonging to the pilot set (S1) Use the same orthogonal code as the pilot (# 5 - # 8).

Therefore, the resources used by the pilot set S2 and the resources used by the pilot set S1 are the same. The pilots (Nos. 9 to 16) belonging to the pilot set S2 use the pilots (Nos. 1 to 8) belonging to the pilot set S1 and the pilots Differentiate. That is, the pilot set S1 and the pilot set S2 can be distinguished through different random numbers (e.g., PN sequences). A random number (e.g., a PN sequence) used to generate a pilot belonging to the pilot set S1 differs from a random number (e.g., a PN sequence) used to generate a pilot belonging to the pilot set S2.

When the pilot set S1 and the pilot set S2 use different random numbers (e.g., PN sequences), channel estimation performance for interference is improved at the time of channel estimation. For example, when the UE performs channel estimation for a pilot (e.g., # 1) belonging to the pilot set S1, it belongs to the pilot set S2 and uses the same resource as the corresponding pilot (e.g., # 1) Interference may occur due to the pilot (eg, number 10). Since the random number (e.g., the PN sequence) of the pilot set S2 is different from the random number (e.g., the PN sequence) of the pilot set S1, the terminal sets a random number (e.g., PN sequence) When the values obtained by multiplying the codes are added, the interference due to the channel component of the pilot set S2 is averaged down.

The resources occupied by the pilots belonging to the pilot set S1 and the pilot set S2 are reused in order not to increase the overhead of a communication system that transmits many multiple beams.

Meanwhile, the embodiment of the present invention can be applied to a mobile communication system (hereinafter referred to as a 'millimeter wave communication system') operating in a millimeter wave band. A millimeter wave communication system will be described in detail with reference to FIG.

3 is a diagram illustrating a mobile communication base station operating in the millimeter waveband and transmitting a plurality of fixed beams BE1a through BE1h according to an embodiment of the present invention.

3 illustrates an example in which the base station allocates the same transmission resources to a plurality of beams BE1a to BE1f and transmits pilots and data to the plurality of terminals UE1a to UE1f through the plurality of beams BE1a to BE1f Respectively. Here, the resource allocated to the beam may include resources for data and resources for pilot. 3, the base station includes four pilots (PLT1 to PLT4) out of the eight pilots (PLT1 to PLT8) in the pilot set S1 and four pilots (PLT5 to PLT8) As shown in Fig. That is, the pilot configuration is S1 = {PLT1, PLT2, PLT3, PLT4}, S2 = {PLT5, PLT6, PLT7, PLT8}.

3 illustrates a case where a total of six UEs UE1a to UE1f receive a data stream from a base station through a multiplex transmission (e.g., multi-user-MIMO) using the same resource. One beam is transmitted to each of the UEs UE1a, UE1b, UE1c, UE1d, UE1e and UE1f, and the UEs UE1g and UE1h are excluded from the multiplexing due to interference due to the adjacent beam.

For such multiple transmissions, the base station may use the pilots (PLT1, PLT2, PLT3, PLT4) belonging to the pilot set S1 and the pilots (PLT5, PLT6) belonging to the pilot set S2.

On the other hand, among the pilots PLT5, PLT6, PLT7 and PLT8 of the pilot set S2, a pilot to use the same resources as the pilots PLT1, PLT2, PLT3 and PLT4 of the pilot set S1 can be set. For example, the pilots PLT5, PLT6, PLT7 and PLT8 of the pilot set S2 can be set to use the same resources in the order of the pilots PLT1, PLT2, PLT3 and PLT4 of the pilot set S1. That is, the pilot PLT1 and the pilot PLT5 use the same resources, the pilot PLT2 and the pilot PLT6 use the same resources, the pilot PLT3 and the pilot PLT7 use the same resources, The pilot (PLT4) and pilot (PLT8) can use the same resources. For another example, pilots that use the same resources among the pilots (PLT1, PLT2, PLT3, PLT4) of the pilot set S1 and pilots PLT5, PLT6, PLT7, PLT8 of the pilot set S2 May be set.

On the other hand, when the pilots PLT1, PLT2, PLT3 and PLT4 of the pilot set S1 and the pilots PLT5, PLT6, PLT7 and PLT8 of the pilot set S2 are set to use the same resources in order, ) And the pilot (PLT5), or the pilot (PLT2) and the pilot (PLT6) use the same resources, so interference may exist. However, since the millimeter wave band has a propagation channel characteristic with a large path attenuation and a limited scattering, in the environment shown in FIG. 3, the base station can use the pilot (PLT1) and the pilot (PLT5) (PLT2) and pilot (PLT6)) without interference.

Thus, in the millimeter wave band, it is possible for the base station to use the pilot belonging to the pilot set S2 with little interference with the pilot belonging to the pilot set S1.

On the other hand, when the base station transmits multiple beams in the millimeter wave band, reflection of the transmission wave occurs sufficiently according to the reflector, so that inter-beam interference in the urban area can not be avoided. A method of minimizing inter-beam interference will be described with reference to FIG.

4 is a diagram showing inter-beam interference caused by a reflector when a base station transmits multiple beams in a millimeter wave band. Specifically, FIG. 4 illustrates a case where a base station covers a service area through a plurality of beams BE2a through BE2h.

 The terminal UE2b receives the beam BE2f transmitted to the terminal UE2a by being reflected by the building OB10, thereby being interfered with. In this way, since the base station may need to perform multiple transmissions in a channel environment where inter-beam interference is unavoidable, the scheduler of the base station must be able to measure the intensity of the inter-beam interference.

For beam-to-beam interference measurement, a beam reference signal (e.g., beam status information (BSI) -RS (reference signal)) transmitted periodically through each fixed beam BE2a-BE2h may be used.

The terminal feeds back the strength of at least one BSI-RS received by itself or the channel quality indicator (CQI) of at least one beam received by the terminal to the base station.

When inter-beam interference is inevitable, the scheduler of the base station predicts the inter-beam interference using the information fed back from the terminal (s) (e.g., the intensity of the BSI-RS or the CQI of the beam) (Or adjusts) the data transmission speed of the beams BE2a to BE2h.

4, even if the pilot set S1 and the pilot set S2 use different random numbers (e.g., PN sequences), degradation of channel estimation performance due to interference between pilots using the same resource can be avoided However, when the base station allocates the pilots belonging to the pilot set S1 and the pilot set S2, the performance degradation can be minimized by this scheduling. When the base station transmits signals to the terminals using beams that interfere with each other, it is impossible for the terminal to receive the corresponding signal due to inter-beam interference or the reception performance of the terminal may deteriorate. Therefore, BE2a to BE2h) can be adjusted (e.g., downwardly adjusted) to increase the overall system capacity. The scheduler of the base station can select a transmission beam set for minimizing interference considering beam-to-beam interference when it is desired to allocate pilot and data to a plurality of beams among a plurality of beams BE2a to BE2h for multiple transmission. A method of selecting a beam for minimizing such interference will be described with reference to Figs. 5 and 6. Fig.

5 is a diagram illustrating a method of allocating pilots in a spatial multiplexing transmission according to an embodiment of the present invention.

The base station sets a pilot set S1 and a pilot set S2 using the same resources and different random numbers (e.g., PN sequences) (S10).

The scheduler of the base station receives channel status information by each fixed beam from the terminal (s) (S11). Specifically, the scheduler of the base station can receive the CQI of each beam from the terminal (s). Here, the CQI of each beam can be measured by the terminal based on each beam reference signal (e.g., BSI-RS) periodically transmitted without inter-beam interference.

The scheduler of the base station calculates inter-beam interference based on the CQI of each beam (S12).

The scheduler of the base station determines the beam (or the number of beams) to be simultaneously transmitted to the terminal (s) using the same resource, based on the calculated inter-beam interference (S13). Specifically, the scheduler of the base station can determine the number of data streams to be multiplexed over multiple beams.

The scheduler of the base station allocates the pilot belonging to the pilot set S1 and S2 to the beam (or data stream) determined in step S13 according to the number of beams (or the number of data streams) determined in step S13 (S14). For convenience of explanation, let the size of the pilot set S1 be Np1, the size of the pilot set S2 be Np2, and the number of beams (or data streams) determined in S13 be Np3. The base station scheduler compares Np3 and Np1. Specifically, if the Np3 is equal to or smaller than Np1, the scheduler of the base station can allocate Np3 pilots among the pilots belonging to the pilot set S1 to Np3 beams (or data streams) determined in S13.

If Np3 exceeds Np1, the scheduler of the base station may first allocate Np1 pilots belonging to pilot set S1 to Np1 beams (or data streams) among Np3 beams (or data streams) determined in S13 . The scheduler of the base station allocates the (Np3 - Np1) of Np2 pilots belonging to the pilot set S2 to the remaining Np3 - Np1 beams (or data Stream).

6 is a diagram illustrating a method for allocating pilots in a spatial multiplexing transmission according to another embodiment of the present invention. The method illustrated in FIG. 6 differs from the method illustrated in FIG. 5 in that the pilot belonging to the pilot set S1, S2 is pre-allocated to the beam.

The base station sets a pilot set S1 and a pilot set S2 using the same resources and different random numbers (e.g., PN sequences) (S20).

The scheduler of the base station preliminarily allocates each pilot belonging to the pilot set (S1, S2) to each fixed beam (S21). Specifically, the scheduler of the base station can allocate one pilot belonging to the pilot set S1, S2 to one fixed beam.

The scheduler of the base station receives channel state information of each fixed beam from the terminal (s) (S22). Specifically, the scheduler of the base station can receive the CQI of each beam from the terminal (s). Here, the CQI of each beam can be measured by the terminal based on each beam reference signal (e.g., BSI-RS) periodically transmitted without inter-beam interference.

The scheduler of the base station calculates inter-beam interference based on the CQI of each beam (S23).

The scheduler of the base station determines the beam (or the number of beams) to be simultaneously transmitted to the terminal (s) using the same resource based on the calculated inter-beam interference (S24). Specifically, the scheduler of the base station can determine the number of data streams to be multiplexed over multiple beams.

The scheduler of the base station allocates the pilot belonging to the multiple beams to be simultaneously transmitted to the data stream determined in step S24, regardless of the number of data streams determined in step S24 (S25). For example, the scheduler of the base station assigns the first pilot and the second pilot among the pilots belonging to the pilot set (S1, S2) to the first beam and the second beam of the plurality of beams in step S21, The first beam and the second beam among the plurality of beams. In this assumption, the base station's scheduler assigns a first pilot assigned to the first beam to a data stream corresponding to a first one of the data streams to be multiplexed through the first beam and the second beam, May be assigned to a data stream corresponding to a second one of the data streams to be multiplexed through the first beam and the second beam.

Meanwhile, the embodiment of the present invention can be applied to a distributed antenna mobile communication system operating in the millimeter wave band. This distributed antenna mobile communication system will be described with reference to FIG.

7 is a diagram illustrating a base station operating in a millimeter wave band and operating a distributed antenna according to an embodiment of the present invention.

The radio service area Ar20 includes a plurality of subareas Ar21 separated by a beam in the omni direction emitted from a plurality of antennas. Here, the service area Ar20 may be one sector that the base station is responsible for.

Due to the proliferation of wireless traffic, the base station can operate a plurality of distributed antennas. In detail, a base station (hereinafter, referred to as a 'distributed antenna base station') that operates a plurality of distributed antennas includes a plurality of RF (Radio Frequency) modules 31 and a digital signal processing module 32 for processing digital signals. Each of the RF modules 31 connected to the distributed antenna is provided in each sub-region Ar21, and the digital signal processing module 32 is disposed in one place. Each RF module 31 and the digital signal processing module 32 are interlocked with each other. In FIG. 7, the 'RF module 31 connected to the distributed antenna' is referred to as a 'distributed antenna 31' for convenience of explanation.

The distributed antenna base station illustrated in FIG. 7 may assign a pilot belonging to the pilot set S1, S2 to each of the distributed antennas 31 using a method similar to the method illustrated in FIG.

Specifically, the distributed antenna base station sets the pilot set S1 and the pilot set S2.

The distributed antenna base station receives feedback of channel state information (e.g., CQI for a distributed antenna) by each of the distributed antennas 31 from the terminal (s).

The distributed antenna base station calculates the interference between the distributed antennas 31 based on the received channel state information.

The distributed antenna base station determines the number of distributed antennas 31 (or the number of distributed antennas 31) to perform multiplex transmission (using the same resources) based on the interference between the distributed antennas 31. [

The distributed antenna base station allocates a pilot belonging to the pilot set S1 and S2 to the data stream to be multiplexed through the determined distributed antenna 31 according to the determined number of the distributed antennas 31. [ For convenience of explanation, it is assumed that the size of the pilot set S1 is Np1, the size of the pilot set S2 is Np2, and the number of the distributed antennas 31 determined is Np4. Specifically, when Np4 is equal to or smaller than Np1, the distributed antenna base station sequentially allocates Np4 pilots among the pilots belonging to the pilot set S1 to the data streams to be multiplexed through the determined Np4 distributed antennas 31 .

If Np4 exceeds Np1, the distributed antenna base station may first allocate Np1 pilots belonging to the pilot set S1 to Np1 data streams among the data streams to be multiplexed through the determined Np4 distributed antennas 31 have. Then, the distributed antenna base station transmits (Np4 - Np1) pilots among the Np2 pilots belonging to the pilot set S2 to the remaining (Np4 - Np1) pilots of the data streams to be multiplexed through the determined Np4 distributed antennas 31 Can be assigned to a data stream.

Alternatively, the distributed antenna base station illustrated in FIG. 7 may assign a pilot belonging to the pilot set S1, S2 to each of the distributed antennas 31 using a method similar to the method illustrated in FIG.

Specifically, the distributed antenna base station can preliminarily allocate each pilot belonging to the set of pilot sets (S1, S2) to each of the distributed antennas (31).

The distributed antenna base station calculates the interference between the distributed antennas 31 based on the channel state information fed back from the terminal (s) (e.g., CQI for each distributed antenna 31).

The distributed antenna base station determines the number of distributed antennas 31 (or the number of distributed antennas 31) to perform multiplex transmission (using the same resources) based on the interference between the distributed antennas 31. [

The distributed antenna base station allocates the pilot allocated in advance to the determined distributed antenna 31 to the data stream to be multiplexed through the determined distributed antenna 31 regardless of the number of the determined distributed antennas 31. [

8 is a diagram illustrating a base station 100, in accordance with an embodiment of the present invention.

The base station 100 includes a processor 110, a memory 120, and an RF converter 130.

The processor 110 may be configured to implement the functions, procedures, and methods described herein in connection with a base station or TP. In addition, the processor 110 can control each configuration of the base station 100.

The memory 120 is coupled to the processor 110 and stores various information related to the operation of the processor 110. [

RF converter 130 is coupled to processor 110 and transmits or receives radio signals.

9 is a diagram illustrating a terminal 200 according to an embodiment of the present invention.

The terminal 200 includes a processor 210, a memory 220, and an RF converter 230.

The processor 210 may be configured to implement the functions, procedures, and methods described herein in connection with a terminal. In addition, the processor 210 can control each configuration of the terminal 200. [

The memory 220 is coupled to the processor 210 and stores various information related to the operation of the processor 210. [

The RF converter 230 is connected to the processor 210 and transmits or receives a radio signal.

Meanwhile, although the embodiment of the present invention has been described by taking as an example the case where the base station transmits data, this is only an example. The embodiment of the present invention can also be applied to a case where a base station transmits a control signal.

Meanwhile, although the embodiment of the present invention has been described with reference to the case where the base station constitutes two pilot sets (S1, S2), this is only an example. The embodiment of the present invention can also be applied to a case where a base station constitutes three or more sets of pilots.

In the meantime, the embodiment of the present invention has been described by way of example of a communication system operating in a propagation channel environment having a limited scattering like a millimeter wave band, but this is merely an example. Embodiments of the present invention can also be applied to communication systems operating in a frequency band other than the millimeter wave band.

In the meantime, the embodiment of the present invention has been described by taking a system using OFDM symbols as an example, but this is merely an example. Embodiments of the present invention may also be applied to systems that use time domain symbols other than OFDM symbols.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (20)

A method for a base station to transmit pilot signals in a multi-antenna communication system,
Comprising the steps of: embedding a portion of a pilot signal divided into at least one of a time domain symbol, a subcarrier, and an orthogonal code into a first set to which a first random number is applied;
A second set of the plurality of pilot signals using the same resources as the resources used by the first set and applying a second random number different from the first random number, Including a pilot signal; And
Transmitting at least one of the pilot signals belonging to the first set and the second set
And transmitting the pilot signal to the base station. The method according to claim 1,
Wherein a first pilot signal and a second pilot signal, which are distinguished from each other by a first orthogonal code among the pilot signals belonging to the second set, are divided into pilot signals belonging to the first set by the first orthogonal code 3 pilot signal and a fourth pilot signal using the same resources
A method of transmitting a pilot signal of a base station. 3. The method of claim 2,
The multi-antenna communication system transmits multiple beams in a millimeter wave band,
Wherein the first orthogonal code is a Walsh code,
The time domain symbol is an orthogonal frequency division multiplexing (OFDM) symbol,
Wherein each of the first random number and the second random number is a PN (pseudo noise) sequence
A method of transmitting a pilot signal of a base station. 3. The method of claim 2,
Wherein the transmitting comprises:
Transmitting at least one of at least one of the pilot signals belonging to the first set and the pilot signal belonging to the second set simultaneously through a plurality of beams
A method of transmitting a pilot signal of a base station. A method for a base station to allocate a pilot in a multi-antenna communication system,
Setting a first pilot set and a second pilot set using the same resources and differentiated through different random numbers; And
Assigning, to a data stream to be multiplexed, a pilot belonging to the first pilot set prior to a pilot belonging to the second pilot set
Wherein the pilot allocation method comprises: 6. The method of claim 5,
Wherein the step of assigning, to the data stream to be multiplexed, a pilot belonging to the first pilot set prior to a pilot belonging to the second pilot set,
Determining a number of data streams to be multiplexed;
Comparing the determined number with the number of pilots belonging to the first pilot set; And
And allocating the determined number of pilots among the pilots belonging to the first set of pilots to the data stream to be multiplexed when the determined number is equal to or less than the number of pilots belonging to the first pilot set
A method of allocating a pilot of a base station. The method according to claim 6,
Wherein the step of assigning, to the data stream to be multiplexed, a pilot belonging to the first pilot set prior to a pilot belonging to the second pilot set,
Assigning a pilot belonging to the first set of pilots to a portion of the data streams to be multiplexed if the determined number is greater than the number of pilots belonging to the first pilot set; And
Further comprising assigning to the remainder of the data streams to be multiplexed a pilot as many as the number of pilots belonging to the first set of pilots in the determined number of pilots belonging to the second set of pilots
A method of allocating a pilot of a base station. The method according to claim 6,
Wherein the step of determining the number of data streams to be multiplexed comprises:
Comprising: receiving channel state information for a plurality of beams from a terminal;
Calculating interference between the plurality of beams based on the channel state information; And
Determining a number of data streams to be multiplexed based on the interference between the multiple beams,
A method of allocating a pilot of a base station. 6. The method of claim 5,
The random number is a PN (pseudo noise) sequence
A method of allocating a pilot of a base station. 6. The method of claim 5,
Wherein the setting of the first pilot set and the second pilot set comprises:
Comprising the step of including in the first pilot set some pilots of the plurality of pilots that are distinguished through at least one of a time domain symbol, a subcarrier, and an orthogonal code; And
And including, among the plurality of pilots, pilots other than the pilots included in the first pilot set in the second pilot set
A method of allocating a pilot of a base station. 9. The method of claim 8,
Wherein receiving channel state information for the plurality of beams comprises:
Transmitting a beam status information (BSI) -RS (reference signal) through the plurality of beams; And
Receiving the channel state information including a channel quality indicator (CQI) measured based on the BSI-RS from a terminal receiving the BSI-RS;
A method of allocating a pilot of a base station. 11. The method of claim 10,
The first pilot and the second pilot, which are classified through the first orthogonal code among the pilots belonging to the second pilot set, may be classified into a third pilot and a second pilot separated from each other by the first orthogonal code among the pilots belonging to the first pilot set, Using the same resources as the pilot and the fourth pilot,
The first orthogonal code is a Walsh code
A method of allocating a pilot of a base station. 6. The method of claim 5,
The base station may include a plurality of antennas
A method of allocating a pilot of a base station. A method for a base station to allocate a pilot in a multi-antenna communication system,
Setting a first pilot set and a second pilot set using the same resources and differentiated through different random numbers;
Allocating, to the plurality of beams, a pilot belonging to the first pilot set and a pilot belonging to the second pilot set;
Determining a pilot allocated to a beam for a data stream to be multiplexed among the plurality of beams; And
Allocating the determined pilot among the pilots belonging to the first pilot set and the second pilot set to the data stream to be multiplexed,
Wherein the pilot allocation method comprises: 15. The method of claim 14,
Wherein the setting of the first pilot set and the second pilot set comprises:
Comprising the step of including in the first pilot set some pilots of the plurality of pilots that are distinguished through at least one of a time domain symbol, a subcarrier, and an orthogonal code; And
And including, among the plurality of pilots, pilots other than the pilots included in the first pilot set in the second pilot set
A method of allocating a pilot of a base station. 16. The method of claim 15,
The first pilot and the second pilot, which are classified through the first orthogonal code among the pilots belonging to the second pilot set, may be classified into a third pilot and a second pilot separated from each other by the first orthogonal code among the pilots belonging to the first pilot set, Using the same resources as the pilot and the fourth pilot,
The first orthogonal code is a Walsh code
A method of allocating a pilot of a base station. 15. The method of claim 14,
Wherein determining the pilot assigned to the beam for the data stream to be multiplexed comprises:
Receiving channel state information for the plurality of beams from a terminal;
Calculating interference between the plurality of beams based on the channel state information; And
Determining a data stream to be multiplexed based on the interference between the plurality of beams,
A method of allocating a pilot of a base station. 18. The method of claim 17,
Wherein receiving channel state information for the plurality of beams comprises:
Transmitting a beam status information (BSI) -RS (reference signal) through the plurality of beams; And
Receiving the channel state information including a channel quality indicator (CQI) measured based on the BSI-RS from a terminal receiving the BSI-RS;
A method of allocating a pilot of a base station. 15. The method of claim 14,
The random number is a PN (pseudo noise) sequence
A method of allocating a pilot of a base station. 15. The method of claim 14,
The base station may include a plurality of antennas
A method of allocating a pilot of a base station.

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