KR20160081771A - Method for transmitting and receiving Random Access Channel in wireless communication systems - Google Patents

Abstract

A method for transmitting and receiving a random access channel in a wireless communication system may include a step of transmitting a transmission beam to the terminal of a region existing in a predetermined cluster, a step of receiving a random access channel signal including a random access code mapped to the cluster, and a step of detecting the random access code by using the random channel signal. So, a signal with a cluster unit can be processed.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for transmitting and receiving a random access channel in a wireless communication system,

The present invention relates to a method for transmitting and receiving a random access channel signal in a wireless communication system, and more particularly, to a method and apparatus for transmitting and receiving a cluster-based random access channel signal in a multi-beam wireless communication system.

In order to meet the ever-increasing demand for wireless data traffic, a method for increasing the data transmission rate of the wireless communication system has been proposed. One of such measures is to increase the bandwidth of the signal. In this case, since it is difficult to secure a wide frequency band in a bandwidth of 10 GHz or less used in a general wireless communication system, a frequency of a millimeter wave (mmWave) band which can secure an idle bandwidth of 1 GHz or more and increase frequency efficiency Cellular communication technology will be used.

SHF band, and EHF band, it is possible to acquire a wide bandwidth, and it is possible to obtain not only time, frequency, and code resources but also space resources through beam shaping based on propagation characteristics having linearity So that the radio capacity can be dramatically increased. However, there is a problem that pathloss and poor penetration characteristics occur due to use of a high frequency, resulting in a decrease in the service area.

In order to solve this problem, in a cellular communication using the mmWave band, a method of operating a plurality of beams based on a beamforming technique of concentrating a service area of a radio wave in a specific direction using a plurality of antennas .

In a wireless communication system using multiple beams, a base station and a plurality of terminals share the same time slot with the same frequency band based on a multi-beam technique and transmit and receive signals. A plurality of terminals receiving the same beam are communicated to the base station by being allocated orthogonal fractions divided in the time or frequency domain. At this time, the transmission beam (uplink) used in the terminal has a broad radiation pattern (Radiation Pattern) compared with a precise transmission / reception beam used in the base station due to physical space constraints, performance constraints, price constraints, When a terminal exists at a position where transmission and reception beams of a base station overlap, there is a high possibility of causing interference between signals transmitted in the uplink.

Particularly, when a terminal initially accesses a base station or performs handover, a time required for random access (RA) due to interference between signals transmitted in the uplink may increase.

Further, when a reflector exists around the mobile station without a precise beam formed between the base station and the mobile station, the beam reflected from the beam reflected by the adjacent reflection beams (LOS) It is possible to transmit the upper link signal of the non-line-of-sight (NLOS) environment at a higher intensity.

According to an embodiment of the present invention, in order to solve the above-mentioned problem, in a wireless communication environment using multiple beams, transmission / reception beams of a base station and random access codes transmitted from a terminal to a base station are grouped into a cluster pair, A method for transmitting and receiving a random access channel signal capable of processing a signal.

Also, by reducing the interference of the signals transmitted from the UEs not belonging to the cluster by the random access channel signal transmitting and receiving method, the delay time occurring in the process of detecting the random access code from the random access channel signal by the base station can be minimized.

The present invention also provides a cluster-based random access channel transmission / reception method capable of enhancing the detection probability of a random access code by efficiently combining dispersed signals by a reflector in the vicinity of a terminal.

A method of transmitting and receiving a signal in a wireless communication according to an exemplary embodiment of the present invention includes transmitting a transmission beam to a terminal in an area existing in a predetermined cluster and transmitting a random access channel signal including a random access code And detecting the random access code using the random access channel signal.

The random access code mapped to the cluster may be a plurality of random access codes.

The transmission beam includes information on a beam ID for identifying the transmission beam, the beam ID and the random access code are mapped, and the beam ID may be transmitted through a synchronization signal or a reference signal of the transmission beam .

A beam transmitted to the terminal may be divided into the cluster units, and a plurality of transmission beams may be transmitted into the cluster.

Information about the cluster may be shared between the BS and the MS or transmitted from the BS to the MS through a system message.

Measuring the strength of the random access channel signal, and implementing signal diversity by comparing the strength of the random access channel signal with a predetermined threshold value.

The signal diversity may be implemented through Maximum Ratio Combining (MRC) or Equal Gain Combining (EGC).

According to another aspect of the present invention, there is provided a method of transmitting and receiving a signal in a wireless communication, the method comprising: detecting a beam ID of a reception beam having the best size among reception beams received; Selecting an access code, and transmitting the random access channel signal including the random access code to a base station.

According to an embodiment of the present invention, there is provided a method and apparatus for transmitting / receiving beams of a base station and random access codes transmitted from a terminal to a base station in a wireless communication environment using multiple beams, A method of transmitting and receiving a random access channel signal is provided.

Also, by reducing the interference of the signals transmitted from the UEs not belonging to the cluster by the random access channel signal transmitting and receiving method, the delay time occurring in the process of detecting the random access code from the random access channel signal by the base station can be minimized.

According to another aspect of the present invention, there is provided a cluster-based random access channel transmission / reception method capable of enhancing the detection probability of a random access code by efficiently combining dispersed signals due to a reflector around a terminal.

FIG. 1 is a diagram illustrating a configuration of a BS and a terminal using multiple beams according to an embodiment of the present invention. Referring to FIG.
2 is a diagram illustrating an example of configuring a sector using a combination of an elevation angle and an azimuth angle of a transmission beam transmitted from a base station according to an embodiment of the present invention.
3 is a diagram illustrating that a mobile station transmits a signal to a base station in an area where transmission and reception beams of a base station are superimposed.
4 is a diagram illustrating that a random access signal transmitted from a terminal is reflected by a reflector in the vicinity of the terminal and is transmitted to a base station.
5 is a flowchart illustrating a method of transmitting and receiving a random access channel signal by a base station according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear.

The components shown in the embodiments of the present invention are shown separately to represent different characteristic functions and do not mean that each component is composed of separate hardware or software constituent units. That is, each constituent unit is included in each constituent unit for convenience of explanation, and at least two constituent units of the constituent units may be combined to form one constituent unit, or one constituent unit may be divided into a plurality of constituent units to perform a function. The integrated embodiments and separate embodiments of the components are also included within the scope of the present invention, unless they depart from the essence of the present invention.

In addition, some of the components are not essential components to perform essential functions in the present invention, but may be optional components only to improve performance. The present invention can be implemented only with components essential for realizing the essence of the present invention, except for the components used for the performance improvement, and can be implemented by only including the essential components except the optional components used for performance improvement Are also included in the scope of the present invention.

In the mmWave band, the base station can generate and operate multiple beams having a plurality of thin and precise beams using a beam forming technique, and can assign an identifier (ID) to each generated beam. The beam identifier information may be transmitted using a synchronization signal or may be transmitted using a reference signal that is separate from the synchronization signal.

For example, in the 3GPP LTE system, the synchronization signal may be a Primary Synchronization Signal (PSS) or a Secondary Synchronization Signal (SSS), and the reference signal may be a pilot that knows the transmission position between the BS and the MS. At this time, the base station is installed at a specific height, and the beam has a predetermined beam width. The beam width of the beam generated at the base station can be defined for each of Elevation Angle and Azimuth.

FIG. 1 illustrates a configuration of a BS and a terminal using multiple beams according to an embodiment of the present invention.

The base station 100 generates multiple beams and transmits them to the terminal 300. As shown, the beam has a predetermined beam width and can be transmitted to the terminal 300 existing in various areas 200 according to the beam width and the transmission direction.

When the base station 100 transmits data using multiple beams, the base station 100 transmits the data to the terminal 300 using the random access channel signal transmitted from the terminal 300 to determine a transmission beam to be transmitted to the terminal 300 ) Is located in which transmission / reception beam area 200 of the base station 100 is located.

At this time, the multi-beam used in the base station 100, that is, the transmission / reception beam has a beam width determined by an elevation angle and an azimuth in advance, and the area 200 processed by the transmission / Can be determined.

The beam transmitted to each area 200 may have a unique ID (e.g., # 1-1 and # 2-1) as described above.

2 is a diagram illustrating an example of configuring a sector using a combination of an elevation angle and an azimuth angle of a transmission beam transmitted from a base station according to an embodiment of the present invention.

The processing region of the beam transmitted and received by the base station 100 can be predetermined and transmitted with a unique transmission / reception beam ID.

By using this, a plurality of transmitting / receiving beams can be classified into clusters 400 that can be bundled and processed. As shown in FIG. 2, the beams having the beam IDs # 1-1 and # 2-1 can be classified and processed into one cluster 400, and the beams having the beam IDs # 3-1 and # 4-1 can be classified into one The clusters 400 can be classified and processed.

 That is, the base station 100 bundles one or more multi-beams into units of a cluster 400 so as to process them in a specific unit, and combines control signals transmitted from the terminal 300 in an arbitrary cluster 400, The effect can be enhanced. In this case, the transmission / reception beam transmitted from the base station can be divided into cluster units (A, B, ..., N) by one or more multiple beams depending on the environment of the coverage area of the transmission / reception beam of the base station, Information may be shared between the BS and the MS or may be transmitted by the BS to the MS through the system message.

Table 1 below shows that the random access codes usable in the base station according to the embodiment of the present invention are divided to correspond to the transmission and reception beam clusters.

cluster A set of random access codes available at the terminal a 1 to A b A + 1 to A + B ... ... n (A + B + ...) +1 to (A + B + ...) + N

As shown in Table 1, A random access codes from 1 to A may be assigned to the cluster a, B random access codes from the A + 1 to A + B may be given to the cluster b, N random access codes from (A + B .. + N) +1 to (A + B .. + N) + N. It is preferable that random access codes mapped to one cluster are assigned at least one or more redundant codes in order to avoid collision.

The number of random access codes included in each cluster is the same (A = B = ... = N) or different values (A? B? N ... N) depending on the range of the area covered by the transmission / reception beam of the base station It is possible.

In addition, the base station may allocate at least one random access code to each transmission / reception beam ID to distinguish beams belonging to the cluster of transmission / reception beams. The assigned random access code is LTE / LTE-Adv. By applying a cyclic shift scheme such as cyclic shift applied to the Zadoff-Chu sequence of the system, it is possible to minimize the collision in a random access procedure between terminals receiving a beam having the same ID.

On the other hand, when the base station uses the clusters shown in Table 1 and the random access codes corresponding thereto, the random access codes for the random access codes included in the clusters (b, c, ..., n) The random access code belonging to one cluster is in a mapping relationship that is not used in the other cluster so that the channel signal is not detected in the receiving beam of the base station cluster (a). In other words, if the transmission beam ID is known, the cluster to which the terminal belongs can be known. As a result, the random access code set to be used in the terminal is obtained. If the base station knows the random access code transmitted from the terminal, . At this time, the random access channel signals for codes other than those shown in Table 1 can use a random access code having a good correlation property with the random access codes shown in Table 1. For example, LTE / LTE-Adv. And a Zadoff-Chu sequence used in a WiBro / WiBro-Adv system.

FIG. 3 is a diagram illustrating a case where a terminal transmits a signal to a base station in a region where transmission and reception beams of a base station are superimposed. FIG. 4 illustrates a case where a random access signal transmitted from the terminal is reflected by a reflector around the terminal, Fig.

When a plurality of beams are generated in the base station 101 as shown in FIG. 3, the transmission beam transmitted from the base station 101 spreads in the form of a sector when there is no obstacle. In this process, when there are a plurality of beams transmitted from the base station, an overlap 201 may occur in an area covered by the beam.

In the case where the terminal 301 exists in the area 201 where the beams overlap, undesired signal interference may occur when the terminal 301 transmits a signal corresponding to the received beam to the base station 101.

For example, the UE 301 may use a random access code mapped to a specific cluster selected based on a transmission beam ID of a base station having the best signal strength among beams received in a region where a transmission beam of the base station overlaps Signal can be generated. As shown, even if the corresponding signals 302 and 303 are transmitted using a random access code mapped to a specific cluster, it is possible to transmit the signal 304 to the adjacent reception beam undesirably. In this case, Lt; / RTI >

Also, as shown in FIG. 4, the terminal may be located in a region where a line-of-sight (LOS) environment and a non-line-of-sight (NLOS) region coexist. In this case, if a reflector 305 such as a building or an obstacle exists around the terminal without forming an accurate beam between the base station and the terminal, at least one of the reflected signals 306 and 307 is a signal 302 and may be transmitted to the base station as a signal of the adjacent beam.

5 is a flowchart illustrating a method of transmitting and receiving a random access channel signal by a base station according to an embodiment of the present invention.

First, the base station may transmit a signal including the transmission beam ID in the divided cluster to the terminal (510).

In this case, regarding the division of the cluster, it is possible to transmit information on whether information is shared between the base station and the terminal or which cluster the base station uses through the system message through the system message. Of course, since the mapping relationship is established between the transmission beam ID and the cluster, the cluster can be identified only by the transmission beam ID.

Also, since the random access channel code is mapped to each specific cluster as described above, the random access channel code may be included in the system message transmitted to the terminal by the base station, and the terminal may respond to the beam transmitted to the terminal through the system message It is possible to grasp the random access code.

The terminal may detect a transmission beam ID having the best signal strength among the received base station transmission beams (520).

A terminal that detects a transmission / reception beam having the best strength selects a cluster of random access codes mapped on a one-to-one basis to a cluster including the detected base station transmission beam ID, and transmits the uplink transmission (530).

The base station performs a correlation process on the random access channel signal with respect to the received uplink using a random access code mapped on a one-to-one basis with the transmission beam transmitted by the base station (540).

The base station also measures a signal-to-noise ratio for a signal output from each reception beam, and performs a process of selecting the signal by comparing it with a certain threshold value for determining the presence or absence of the signal (550).

The base station selects maximum ratio combining (MRC) or equal gain combining (EGC) to obtain a diversity effect on a reception beam signal in a cluster exceeding a certain threshold value in a process of selecting signals and distinguishing them from noise. Combining) can be performed.

A diversity technique is used as a countermeasure against fading due to multi-path in mobile communication. Multipath means that multiple transmit signals are received by the receive antenna over several paths in the air. When multiple signals are received through different paths, they experience different amplitude attenuation and phase changes. When these signals are combined when they are received, the intensity of the signal changes according to the time change, which is called fading. The diversity scheme overcomes fading by receiving multiple signals affected by independent fading and combining them appropriately.

The maximum ratio combining method, the same gain combining method, and the selective combining method described above may exist as methods for synthesizing the respective signals affected by the fading from the diversity branch.

The maximum ratio combining method is a method of combining each signal with the best ratio. The same gain combining method is a method of combining signals in the same phase. The selective combining method compares all signals received from different branches at a given time It is the way to choose the best signal.

The base station then determines the random access code transmitted at the terminal using the combined random access channel signal (560). Accordingly, it is possible to minimize the interference from the adjacent terminals and reduce the delay time generated in the process of detecting the random access code.

As described above, the present invention relates to a method and apparatus for transmitting / receiving a cluster-based random access channel signal in a multi-beam wireless communication system, and a method and apparatus for transmitting / The delay time occurring in the process of detecting the random access code from the random access channel signal by the base station can be minimized.

The present invention also provides a cluster-based random access channel transmission / reception method capable of enhancing the detection probability of a random access code by efficiently combining dispersed signals by a reflector in the vicinity of a terminal.

In the above-described embodiments, the methods are described on the basis of a flowchart as a series of steps or blocks, but the present invention is not limited to the order of steps, and some steps may occur in different orders or in a different order than the steps described above have. It will also be understood by those skilled in the art that the steps depicted in the flowchart illustrations are not exclusive and that other steps may be included or that one or more steps in the flowchart may be deleted without affecting the scope of the invention You will understand.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

100: base station
300: terminal

Claims (11)

A method for transmitting and receiving signals in a wireless communication,
Transmitting a transmission beam to a terminal in an area existing in a predetermined cluster;
Receiving a random access channel signal including a random access code mapped to the cluster;
And detecting the random access code using the random access channel signal. The method according to claim 1,
Wherein the random access code mapped to the cluster is a plurality of random access codes. The method according to claim 1,
Wherein the transmission beam includes information on a beam ID for identifying the transmission beam,
The beam ID and the random access code are mapped,
Wherein the beam ID is transmitted through a synchronization signal or a reference signal of the transmission beam. The method according to claim 1,
The beam transmitted to the terminal may be divided into the cluster units,
Wherein a plurality of transmission beams can be transmitted into the clusters. The method according to claim 1,
Wherein information on the cluster is shared between the base station and the terminal or transmitted from the base station to the terminal through a system message. The method according to claim 1,
Measuring the strength of the random access channel signal;
And comparing the strength of the random access channel signal with a predetermined threshold to implement signal diversity. The method according to claim 6,
Wherein the signal diversity is implemented through maximum ratio combining (MRC) or equal gain combining (EGC). A method for transmitting and receiving signals in a wireless communication,
Detecting a beam ID of the reception beam having the best size among the reception beams received;
Selecting a random access code mapped to a predetermined cluster corresponding to the beam ID;
And transmitting a random access channel signal including the random access code to a base station. 9. The method of claim 8,
Wherein the random access code mapped to the cluster is a plurality of random access codes. 9. The method of claim 8,
Wherein the beam ID and the random access code are mapped. 9. The method of claim 8,
Wherein the beam ID is transmitted through a synchronization signal or a reference signal of the reception beam.

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