KR102397580B1 - Terminal, initial access method thereof, and operating method of base station - Google Patents

Abstract

A terminal, an initial access method thereof, and a method of operating a base station are disclosed. First, the entire preamble may be divided into a plurality of preamble sets corresponding to application services requested by the terminal. When the application service is the first application service, the terminal may select a first preamble from a first preamble set among a plurality of preamble sets and transmit the first preamble to the first base station.

Description

A terminal, its initial access method, and an operation method of a base station

The present invention relates to a terminal, an initial access method thereof, and a method of operating a base station.

In the current wireless network, the UE initially accesses it using orthogonal preambles. The base station distinguishes each terminal through a preamble orthogonal to each other, and permits connection of the terminal through an authentication procedure.

However, in the existing method, when a plurality of terminals simultaneously use the same specific preamble, collisions may occur. Each of the preambles included in the entire preamble is orthogonal to each other, but when a plurality of terminals select the same preamble, they collide with each other during a random access process, so that initial access may not be performed.

In order to solve this problem, a method of dividing a preamble set by user class has been proposed in an existing method. That is, since a terminal having a high user rating selects its own preamble from a preamble set having a larger number, the possibility of overlapping preambles can be reduced. Although this method can also prevent collision by dividing the preamble, it is difficult to predict how much load the corresponding terminal generates to the base station when the terminal initially accesses it.

An object of the present invention is to provide an initial access method of a terminal that improves the initial access success probability.

Another object to be solved by the present invention is to provide an initial access method for a terminal that effectively reduces a load on a base station.

According to an embodiment of the present invention, an initial access method of a terminal is provided. The initial access method includes dividing an entire preamble into a plurality of preamble sets corresponding to an application service requested by the terminal, and when the application service is a first application service, in a first preamble set among the plurality of preamble sets It may include selecting a first preamble, and transmitting the first preamble to a first base station.

The initial access method includes, when the application service is a second application service, selecting a second preamble from a second preamble set among the plurality of preamble sets, and transmitting the second preamble to the first base station. may further include.

The initial access method includes: receiving an initial access failure indicating that the first application service corresponding to the first preamble cannot be provided from the first base station; and receiving the initial access failure from the first base station In this case, the method may further include transmitting the first preamble to a second base station.

In the initial access method, receiving an initial access failure from the first base station indicating that the first application service corresponding to the first preamble cannot be provided, receiving the initial access failure from the first base station In this case, the method may further include selecting a third preamble from a third preamble set indicating an exception condition among the plurality of preamble sets, and transmitting the third preamble to the first base station.

When the first base station receives the third preamble from the terminal, the first base station may accept the initial access of the terminal.

The first application service may be an application service requiring more resources than the second application service.

The first application service and the second application service may be services corresponding to different QoS Class Identifiers (QCIs).

The plurality of preamble sets may be received from a system server, and the terminal and the first base station may share the plurality of preamble sets with each other.

According to another embodiment of the present invention, a method of operating a base station for initial access of a terminal is provided. The method includes dividing an entire preamble into a plurality of preamble sets corresponding to an application service requested by the terminal, and when the application service is a first application service, a first preamble set selected from among the plurality of preamble sets Receiving a first preamble from the terminal, and determining whether the first application service corresponding to the first preamble can be provided.

The determining may include determining whether it is possible to provide the first application service by adding up the traffic required by the first application service and the current traffic of the first base station.

The operating method may further include transmitting an initial access failure to the terminal when it is impossible to provide the first application service in the determining step.

The method includes: receiving, from the terminal, a second preamble selected from a third preamble set indicating an exception condition among the plurality of preamble sets;

When receiving the second preamble from the terminal, the method may further include accepting the initial access of the terminal.

The first application service may be an application service requiring more resources than the second application service.

According to another embodiment of the present invention, a terminal is provided. The terminal includes a memory for storing a plurality of preamble sets divided in response to an application service, a processor for selecting a first preamble from a first preamble set among the plurality of preamble sets when the application service is a first application service, and and an RF module for transmitting the first preamble to the first base station.

When the application service is a second application service, the processor may select a second preamble from a second preamble set among the plurality of preamble sets, and the RF module may transmit the first preamble to the first base station. .

When the processor receives an initial access failure indicating that the first application service corresponding to the first preamble cannot be provided from the first base station, the processor transmits the first preamble to a second base station through the RF module can be transmitted

When the RF module receives an initial access failure indicating that the first application service corresponding to the first preamble cannot be provided from the first base station, the processor is configured to: A third preamble may be selected from the set of 3 preambles, and the RF module may transmit the third preamble to the first base station.

When the first base station receives the third preamble from the terminal, the first base station may accept the initial access of the terminal.

The first application service may be an application service requiring more resources than the second application service.

The plurality of preamble sets may be received from a system server, and the terminal and the first base station may share the plurality of preamble sets with each other.

According to an embodiment of the present invention, since the terminal selects a preamble corresponding to the application service requested by the terminal and the base station can also determine whether to allow initial access through the preamble, the initial access probability can be improved.

According to an embodiment of the present invention, it is possible to prevent a situation in which only a specific base station is saturated by predicting traffic to be used by the terminal and inducing access to another base station.

1 is a diagram illustrating a wireless communication system according to an embodiment of the present invention.
2 is a diagram illustrating a method of dividing a preamble according to an embodiment of the present invention.
3 is a diagram illustrating an initial access method of a terminal according to an embodiment of the present invention.
4 is a diagram illustrating a method for a terminal to additionally access when an initial connection fails according to an embodiment of the present invention.
5 is a diagram illustrating a method for a terminal to initially access in an exceptional situation according to an embodiment of the present invention.
FIG. 6 is a flowchart showing the flow of messages in the initial connection of FIG. 3 .
Fig. 7 is a flow chart showing the message flow in the initial connection of Fig. 4;
Fig. 8 is a flow chart showing the flow of messages in the initial connection of Fig. 5;
9 is a diagram illustrating a terminal according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, a terminal is a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), a high reliability mobile station (HR-MS) ), a subscriber station (subscriber station, SS), a portable subscriber station (PSS), an access terminal (AT), user equipment (UE), and the like, and may refer to a terminal, MT, It may include all or some functions of AMS, HR-MS, SS, PSS, AT, UE, and the like.

In addition, the base station (base station, BS) is an advanced base station (advanced base station, ABS), a high reliability base station (high reliability base station, HR-BS), a Node B (node B), an advanced node B (evolved node B, eNodeB), an access point (AP), a radio access station (RAS), a base transceiver station (BTS), a mobile multihop relay (MMR)-BS, a relay serving as a base station station, RS), may refer to a high reliability relay station (HR-RS) that serves as a base station, etc., and may also refer to BS, ABS, NodeB, eNodeB, AP, RAS, BTS, MMR-BS, RS , HR-RS, etc. may include all or some functions.

The terminal according to the embodiment of the present invention initially accesses by using a separate preamble set for each service type requested by the terminal. Through this, it is possible to increase the initial access probability of the terminal by preventing a phenomenon in which a load is concentrated on a specific base station. An initial access method according to an embodiment of the present invention will be described.

1 is a diagram illustrating a wireless communication system according to an embodiment of the present invention.

As shown in FIG. 1 , the wireless communication system according to an embodiment of the present invention includes a plurality of base stations 110 and a plurality of terminals 120 .

Referring to FIG. 1 , in a wireless communication system according to an embodiment of the present invention, a plurality of base stations 110 and a plurality of terminals 120 are clustered together. In this way, an environment in which the plurality of base stations 110 are dense with each other is referred to as a small dense network. By disposing a plurality of base stations 110 having a small coverage at a high density, an areal capacity per area may be improved. In a situation in which a plurality of base stations 110 are densely populated, the number of selectable base stations from the standpoint of the terminal 120 may increase. However, when a plurality of terminals 120 are concentrated to a specific base station 110 at once, the specific base station 110 is not able to smoothly process traffic due to a large load. The initial access method of the terminal according to the embodiment of the present invention described below can effectively control the load of the base station even in such a small dense network.

The terminal 120 may select one base station from among the plurality of base stations 110 and access it using an initial access protocol (eg, a random access process of LTE, an access process of WiFi). Here, the terminal 120 according to the embodiment of the present invention initially accesses using different preambles according to the type of application service to be used. Through this, the base station 110 can predict the load of the terminal 120 attempting to access and control the access of the terminal accordingly to prevent overload (oversaturation) of the base station 110 .

2 is a diagram illustrating a method of dividing a preamble according to an embodiment of the present invention.

As shown in FIG. 2 , the preamble according to the embodiment of the present invention may be divided into separate sets for each service type. The division of such a preamble may be arbitrarily divided in advance by a system operator (system server). The entire preamble set is divided into a plurality of preamble sets (groups) for each service type requested by the UE. In FIG. 2, it is assumed that the entire preamble set has N preambles. A service type A (A) 210 includes 1-a-th preambles among all preambles, and a service type B (service type B) 220 includes (a+1)-b-th preambles among all preambles. and, the service type C (service type C) 230 includes (b+1) to c-th preambles among all preambles. And the remaining (c+1) to N-th preamble is a preamble set 240 for an exception situation, for example, a preamble set for a terminal access failure situation.

Service type A 210 is a case in which the data requirement of the terminal is high, service type B 220 is a case in which the data requirement of the terminal is medium, and service type C 230 is a case in which the data requirement of the terminal is low. . In addition, service type A 210 is a case in which the estimated resource consumption of the terminal is high, service type B is a case in which the estimated resource consumption of the terminal is medium, and service type C is a case in which the estimated resource consumption of the terminal is high. may be low.

On the other hand, the QoS Class Identifier (QCI) mentioned in 3GPP LTE may be a criterion for dividing the preamble set. QCI expresses the grade of the application that the terminal intends to use, and has a value from 1 to 9. The closer the QCI is to 1, the higher the QoS requirements are, and the closer the QCI is to 9, the lower the QoS requirements are. If the entire preamble set is divided based on this, all N preambles may be divided into 9 subsets. The number of preambles included in each subset may or may not be equal. In order to reduce the collision probability for a terminal using a service with a high QoS requirement, a larger number of preambles may be allocated to a value having a low QCI value. For example, assuming that there are a total of 128 preambles, by disposing 64 in the preamble subset corresponding to QCI=1, terminals using an application service with QCI=1 can reduce the probability of collision with each other. A separate preamble segmentation scheme may be operated not only based on QCI but also for military networks or disaster networks.

In this way, when the entire preamble is divided into a plurality of subsets (groups), the system server delivers the corresponding information to the terminal and the base station. The terminal and the base station store the received preamble segmentation therein, and upon initial access, select a preamble for each service type for initial access.

Referring to FIG. 2 , a terminal requesting service type A arbitrarily selects one preamble from the 1st to a-th preambles and then initially accesses the base station. A terminal requesting service type B arbitrarily selects one preamble from (a+1) to b-th preambles and initially accesses the base station, and a terminal requesting service type C arbitrarily selects one preamble from (b+1) to c-th preambles. After selecting the preamble of , initial access to the base station. As described above, since the terminal arbitrarily selects a preamble from a preamble subset corresponding to the service type requested by the terminal, the initial access probability can be improved.

3 is a diagram illustrating an initial access method of a terminal according to an embodiment of the present invention.

As shown in FIG. 2, the entire preamble set is divided into a plurality of preamble sets (ie, preamble subsets, preamble groups), and the UE initially accesses the preamble set (preamble set) corresponding to the type (type) of the application service it wants to use. subset) is selected. In FIG. 3 , it is assumed that service type C is for a voice call and includes (b+1) to c-th preambles 230 . When the terminal 120 wants to use a voice call, since the voice call application service is service type C, the terminal 120 arbitrarily selects one preamble from the (b+1) to c-th preambles 230 and selects a base station ( 110) is initially connected. When this initial access fails, the terminal 120 attempts to access a base station other than the base station 110 . On the other hand, when there is no other base station in the vicinity, the terminal may retry access to the base station 110 in which initial access has failed through the preamble set 240 for an exception situation.

When the terminal 120 attempts an initial access according to an application service type as shown in FIG. 3 , the base station 110 receives a preamble from the terminal 120 . In this case, the base station 110 may distinguish to which set (ie, a preamble subset) the preamble received from the terminal 120 belongs. Since the base station 110 already knows the preamble set for each application service as shown in FIG. 2 , the service type (eg, resource demand) requested by the terminal can be known through the preamble received from the terminal 120 . Accordingly, the base station 110 predicts the service quality required by the terminal 120 through the reception preamble and then determines whether the corresponding service can be provided. Here, the criteria for determining whether the base station 110 provides a corresponding service may be radio resource usage and currently used backhaul capacities. When the base station 110 determines that its radio resource is saturated, it may be advantageous in terms of load balancing between the base stations to give up the connection of the terminal 120 . However, as described in FIG. 5 below, when there is only one base station to which the terminal can connect, the terminal attempts to access the base station by using the preamble set 240 for an exception situation even if the initial access fails in the first place. can

4 is a diagram illustrating a method for additional access by the terminal 120 when the initial access fails according to an embodiment of the present invention.

As shown in FIG. 4 , the terminal 120 selects one preamble from a set of preambles corresponding to service type C and attempts to initially access the first base station 110a. At this time, the base station 110a determines whether or not saturation is achieved by adding the traffic currently processed by the base station 110a and the traffic to be newly generated upon request by the terminal 120 . When it is determined that the sum of traffic is saturated, the first base station 110a may not proceed with the initial access procedure. In this case, the terminal 120 retries the initial access to another second base station 110b. The second base station 110b performs an initial access process with the terminal 120 when it is determined that its own traffic is not saturated.

Referring to FIG. 4 , when the terminal 120 selects an appropriate preamble according to the application service and accesses the first base station 110a, the first base station 110a may not be able to handle the traffic of the terminal 120 . . In this case, the first base station 110a rejects the access of the terminal 120 . However, unlike FIG. 4 , when there is only one base station to which the terminal 120 can access (ie, the second base station 110b does not exist), the initial access procedure may be significantly delayed. In order to solve this problem, as described with reference to FIG. 2 , the preamble set 240 for an exception situation may be used. The terminal 120 attempts an initial access by using one preamble arbitrarily in the exceptional situation preamble set 240 . When receiving such an exception preamble from the terminal 120 , the first base station 110a may adjust the track service of other terminals and allow the initial access of the terminal 120 . This method will be described in more detail with reference to FIG. 5 below.

5 is a diagram illustrating a method for the terminal 120 to initially access in an exceptional situation according to an embodiment of the present invention.

As shown in FIG. 5 , the terminal 120 arbitrarily selects one preamble from a set of preambles corresponding to its own service type C and attempts to initially access the base station 110 . When the base station 110 determines that the traffic it can handle is saturated, it notifies the terminal 120 of this. In this case, the terminal 120 arbitrarily selects one preamble from among the preamble sets for the exceptional situation, that is, (c+1) to the N-th preamble, and initially accesses it. When the base station 110 receives the preamble for an exception from the terminal 120 , the terminal 120 allows the initial access.

FIG. 6 is a flow chart showing the flow of messages in the initial connection of FIG. 3 .

First, the base station 110, the terminal 120, and the system server 130 share the preamble set shown in FIG. 2 with each other (S610). The system server 130 may divide the preamble for each service type as shown in FIG. 2 , and transmit the divided preamble information to the base station 110 and the terminal 120 .

The terminal 120 determines a preamble set (preamble subset) corresponding to its requested application service type and arbitrarily selects one preamble from the determined preamble set (S620).

The terminal 120 transmits the preamble selected in step S620 to the base station 110 to attempt an initial access (S630).

The base station 110 determines which service type the preamble received from the terminal 120 is a preamble set, and determines whether to accept the initial connection of the terminal 120 (S640). That is, since the base station 110 already knows the preamble set for each application service in step S610, the type of service requested by the terminal (eg, data request amount or resource demand amount) can be known through the preamble received from the terminal 120 . there is. Then, the base station 110 determines whether to accept the initial connection by predicting the service quality required by the terminal 120 through the reception preamble and determining whether the corresponding service can be provided.

When the base station 110 determines that it is possible to provide the service requested by the terminal 120, the base station 110 performs a subsequent initial access process with the terminal 120 (S650). Here, since the subsequent initial access process can be known to those of ordinary skill in the art to which the present invention pertains, a detailed description thereof will be omitted.

As described above, according to an embodiment of the present invention, since the terminal selects a preamble corresponding to the type of application service requested by the terminal and the base station can also determine whether to allow initial access through the preamble type, the initial access probability can be improved. .

Fig. 7 is a flow chart showing the message flow in the initial connection of Fig. 4;

First, the first and second base stations 110a and 110b, the terminal 120, and the system server 130 share the preamble set shown in FIG. 2 with each other (S710). The system server 130 may divide the preamble for each service type as shown in FIG. 2 , and transmit the divided preamble information to the first and second base stations 110a and 110b and the terminal 120 .

The terminal 120 determines a preamble set (preamble subset) corresponding to its requested application service type and arbitrarily selects one preamble from the determined preamble set (S720).

The terminal 120 transmits the preamble selected in step S720 to the first base station 110a to attempt an initial access (S730).

The first base station 110a determines which service type the preamble set corresponds to the preamble received from the terminal 120 and determines whether to accept the initial connection of the terminal 120 (S740). The first base station 110a determines whether saturation is achieved by adding the traffic currently processed by the first base station 110a and the newly generated traffic requested by the terminal 120 . When it is determined that the sum of traffic is saturated, the first base station 110a may not proceed with the initial access procedure.

When it is determined that the first base station 110a does not proceed with the initial access in step S740, it transmits an initial access failure to the terminal 120 (S750).

When receiving the initial access failure from the first base station 110a, the terminal 120 transmits a preamble to the second base station 110b to retry the initial access (S760).

The second base station 110b determines which service type the preamble received from the terminal 120 is a preamble set, and determines whether to accept the initial connection of the terminal 120 (S770).

When the second base station 110b determines that it is possible to provide the service requested by the terminal 120, the second base station 110b performs a subsequent initial access process with the terminal 120 (S780).

As described above, according to an embodiment of the present invention, by predicting traffic to be used by the terminal and inducing access to another base station, a situation in which only a specific base station is saturated can be prevented. From the standpoint of the terminal, the capacity of the entire network can be improved by accessing another base station with more traffic than accessing the saturated base station.

Fig. 8 is a flow chart showing the flow of messages in the initial connection of Fig. 5;

The base station 110, the terminal 120, and the system server 130 share the preamble set shown in FIG. 2 with each other (S810). The system server 130 may divide the preamble for each service type as shown in FIG. 2 , and transmit the divided preamble information to the base station 110 and the terminal 120 .

The terminal 120 determines a preamble set (preamble subset) corresponding to its requested application service type and arbitrarily selects one preamble from the determined preamble set (S820).

The terminal 120 transmits the preamble selected in step S820 to the base station 110 to attempt an initial access (S830).

The base station 110 determines which service type the preamble received from the terminal 120 is a preamble set, and determines whether to accept the initial connection of the terminal 120 (S840). The base station 110 determines whether saturation is achieved by adding the traffic currently processed by the base station 110 and the newly generated traffic requested by the terminal 120 . When it is determined that the sum of traffic is saturated, the base station 110 may not proceed with the initial access procedure.

The base station 110 transmits an initial access failure to the terminal 120 when it is determined that the initial access is not performed in step S840 (S850).

When receiving the initial access failure from the base station 110, the terminal 120 arbitrarily selects one preamble from a set of preambles for an exceptional situation (S860).

Then, the terminal 120 transmits the preamble selected in step S860 to the base station 110 to attempt an initial access (S870).

The base station 110 determines which service type the preamble received from the terminal 120 is a preamble set, and determines whether to accept the initial connection of the terminal 120 (S880).

When the base station 110 determines that the preamble received from the terminal 120 is a preamble for an exceptional situation, the base station 110 performs a subsequent initial access procedure of the terminal 120 . That is, the base station 110 allows the initial access of the terminal 120 when receiving the preamble for the exception.

As described above, according to an embodiment of the present invention, by setting a separate preamble for an exceptional situation and allowing the initial access when the terminal accesses using the preamble, it is possible to prepare for an exceptional situation (emergency situation).

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

As shown in FIG. 9 , the terminal 120 according to an embodiment of the present invention includes a processor 121 , a memory 122 , and an RF module 123 .

The processor 121 may be configured to implement the formats, methods, and functions described with reference to FIGS. 1 to 8 .

The memory 122 is connected to the processor 121 and stores various information related to the operation of the processor 121 .

The RF module 123 is connected to an antenna (not shown) and transmits or receives a radio signal. In addition, the antenna may be implemented as a single antenna or multiple antennas (MIMO antenna).

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the right.

Claims (20)

As an initial access method of a terminal,
dividing the entire preamble into a plurality of preamble sets according to application services available to the terminal;
selecting a first preamble from a first preamble set corresponding to the first application service among the plurality of preamble sets when the application service to be used by the terminal is a first application service;
transmitting the first preamble to a first base station;
selecting a second preamble from a second preamble set corresponding to the second application service from among the plurality of preamble sets when the application service to be used by the terminal is a second application service;
transmitting the second preamble to the first base station
Receiving an initial access failure indicating that the first application service corresponding to the first preamble cannot be provided from the first base station;
selecting a third preamble from a third preamble set indicating an exception condition among the plurality of preamble sets when the initial access failure is received from the first base station; and
and transmitting the third preamble to the first base station. delete According to claim 1,
Receiving an initial access failure indicating that the first application service corresponding to the first preamble cannot be provided from the first base station; and
and transmitting the first preamble to a second base station when receiving the initial access failure from the first base station. delete According to claim 1,
When the first base station receives the third preamble from the terminal, the initial access method accepts the initial access of the terminal. According to claim 1,
The first application service is an application service that requires more resources than the second application service. According to claim 1,
The first application service and the second application service are services corresponding to different QoS Class Identifiers (QCIs). According to claim 1,
The plurality of preamble sets are received from a system server, and the terminal and the first base station share the plurality of preamble sets with each other. A method of operating a base station for initial access of a terminal, comprising:
dividing the entire preamble into a plurality of preamble sets according to application services available to the terminal;
receiving, from the terminal, a first preamble selected from a first preamble set corresponding to the first application service among the plurality of preamble sets when the application service to be used by the terminal is a first application service;
determining whether the first application service corresponding to the first preamble can be provided;
If it is impossible to provide the first application service in the determining step, transmitting an initial connection failure to the terminal;
receiving, from the terminal, a second preamble selected from a third preamble set indicating an exception condition among the plurality of preamble sets; and
and accepting the initial access of the terminal when receiving the second preamble from the terminal. 10. The method of claim 9,
The determining may include determining whether it is possible to provide the first application service by adding up the traffic required by the first application service and the current traffic of the base station. delete delete delete A memory for storing a plurality of preamble sets divided according to available application services;
A processor that selects a first preamble from a first preamble set corresponding to the first application service from among the plurality of preamble sets when the desired application service is the first application service; and
and an RF module for transmitting the first preamble to a first base station,
When the application service to be used is a second application service, the processor selects a second preamble from a second preamble set corresponding to the second application service from among the plurality of preamble sets, and the RF module is configured to transmits to the first base station,
When the RF module receives an initial access failure indicating that the first application service corresponding to the first preamble cannot be provided from the first base station, the processor is configured to: The terminal selects a third preamble from a set of 3 preambles, and the RF module transmits the third preamble to the first base station. delete 15. The method of claim 14,
When the processor receives an initial access failure indicating that the first application service corresponding to the first preamble cannot be provided from the first base station, the processor transmits the first preamble to the second base station through the RF module transmitting terminal. delete 15. The method of claim 14,
When the first base station receives the third preamble from the terminal, the terminal accepts the initial access of the terminal. 15. The method of claim 14,
The first application service is an application service that requires more resources than the second application service. 15. The method of claim 14,
The plurality of preamble sets are received from a system server, and the terminal and the first base station share the plurality of preamble sets with each other.

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