KR20170082763A - Method and apparatus for controlling random access based on compressed sensing - Google Patents

Abstract

A random access control method and apparatus using compression sensing are disclosed. A method for controlling random access using a plurality of user terminals belonging to a base station by using compression sensing includes a sequence matrix including non-orthogonal sequences for identifying each of a plurality of user terminals requesting multiple accesses Assigning a different sequence included in the sequence matrix to each of the plurality of user terminals, generating a sequence corresponding to a preamble requesting random access from at least one of the plurality of user terminals, And transmitting a message indicating that the random access is completed to the user terminal requesting the random access based on the received sequence.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a random access control method and apparatus using compression sensing,

The present invention relates to a technique for avoiding a collision that occurs when a plurality of user terminals make multiple connections in a wireless communication system.

As science and technology change rapidly, the development of science and technology has been applied in daily life environment. Particularly, smart phones, tablet PCs, Bluetooth devices, and the like are contributing to many users, and as users use various terminal devices, the technologies of wireless communication are remarkable. It has made a remarkable development. For example, various wireless communication technologies have been used in fields such as Ubiquitous, M2M (Machine to Machine), and Internet Of Things (IOT).

Particularly, in a wireless communication system, a plurality of user terminals are connected at the same time, and various problems occur in data transmission. For example, as a plurality of terminals simultaneously communicate, the interference signal increases at each terminal. As a result, the size of the transmission signal is received at a relatively low rate as compared with the interference signal and noise. This causes a problem that the probability of success of the information transmission is lowered.

In the IEEE 802.11, IEEE 802.16, and IEEE 802.15 based wireless communication systems, there is a high probability that the terminals collide with each other in a contention access interval before data transmission, Occurs. In particular, it is necessary to lower the initial access delay time as much as possible in order to process it according to the importance of the information. For example, IEEE 802.11 reduces initial access delay time based on CSMA / CA (Carrier Sense Multiple Access / Collision Avoid). In other words, it avoids collision by sending a RTS / CTS (Request To Send / Clear To Send) signal before transmitting data. In LTE (Long Term Evolution), a channel to be connected is separated from a channel to which data is transmitted to perform random access, thereby avoiding collision due to multiple access.

In this way, it is possible to avoid some collisions due to multiple accesses using CSMA / CA or RTS / CTS. However, when a large number of user terminals simultaneously access the Internet (IoT) and M2M, There is a limit to avoiding collisions. For example, in the case of LTE, the user terminal arbitrarily selects one of 64 preambles to attempt connection to the base station. At this time, when there are 30 or more user terminals attempting to access at the same time, the probability that the same preamble is selected in each terminal increases. As a result, it is difficult for at least one terminal to avoid a collision, resulting in a long increase in the multiple access delay time.

Therefore, there is a need for a technique for avoiding collision due to multiple access in a wireless communication environment such as Internet of Things, M2M, etc. without using 64 restricted preambles.

[1] G. Bianchi, "Performance analysis of the IEEE 802.11 distributed coordination function," IEEE J. Sel. Areas Communication., Vol. 18, no. 3, pp. 535-547, Mar. 2000. [2] A. K. Fletcher, S. Rangan, and V. K. Goyal, "A sparsity detection framework for on-off random access channels," Proc. IEEE ISIT, Seoul, Korea, Jun./Jul. 2009, pp. 169-173. [3] M. J. Wainwright, "Sharp thresholds for high-dimensional and noisy sparsity recovery using l1-constrained quadratic programming," IEEE Trans. Inf. Theory, vol. 55, no. 5, pp. 2183-2202, May 2009. [4] J. P. Hong, W. Choi, B.D. Rao, "Sparsity controlled random multiple access with compressed sensing," IEEE Trans. Wireless Communications, vol. 14, no. 2, pp. 998-1010, Feb. 2015.

The present invention relates to a technique for avoiding collision between terminals even when a large number of user terminals simultaneously request a connection to a base station in a wireless communication environment.

The present invention also relates to a technique for dynamically setting a period of a Physical Random Access Channel (PRACH), which is a channel for transmitting a preamble from a user terminal to a base station for a connection request, according to the number of users requesting connection will be.

A method for controlling random access using a plurality of user terminals belonging to a base station by using compression sensing includes a sequence matrix including non-orthogonal sequences for identifying each of a plurality of user terminals requesting multiple accesses Assigning a different sequence included in the sequence matrix to each of the plurality of user terminals, generating a sequence corresponding to a preamble requesting random access from at least one of the plurality of user terminals, And transmitting a message indicating that the random access is completed to the user terminal requesting the random access based on the received sequence.

According to an aspect of the present invention, the step of allocating different sequences included in the sequence matrix may allocate a column-by-column sequence to each user terminal among the sequences included in the sequence matrix.

According to another aspect of the present invention, the step of transmitting a message indicating that the random access is completed may include: when a number of terminals simultaneously requesting random access among the plurality of user terminals is less than a predetermined threshold value, The mobile station can determine the terminal that transmitted the preamble requesting the random access.

According to another aspect, each vector included in the sequence matrix may be a random variable following a Gaussian distribution.

According to another aspect, the message indicating that the random access is completed may indicate a Radio Resource Control Connection Setup message.

According to another aspect of the present invention, the step of allocating the different sequences included in the sequence matrix includes: dynamically allocating a time period of a physical random access channel based on the number of user terminals requesting the random access And the step of receiving the sequence corresponding to the preamble may receive the sequence corresponding to the preamble through the physical random access channel.

According to another aspect of the present invention, the step of receiving a sequence corresponding to a preamble requesting the random access may include a step of generating a connection conflict in a user terminal requesting a sequence corresponding to a preamble requesting the random access Accordingly, the user terminal can receive the sequence corresponding to the preamble again after the predetermined backoff time.

A random access control apparatus for controlling random access using compression sensing for a plurality of user terminals includes a sequence matrix including non-orthogonal sequences for identifying each of a plurality of user terminals requesting multiple accesses, A sequence allocator for allocating different sequences included in the sequence matrix to each of the plurality of user terminals, and a preamble for requesting random access from at least one of the plurality of user terminals and an information transmitting and receiving unit for receiving a sequence corresponding to the preamble and transmitting a message indicating that the random access is completed to the user terminal requesting the random access based on the received sequence.

According to an aspect of the present invention, the sequence assignment unit may assign a column-by-column sequence to each user terminal among sequences included in the sequence matrix.

According to another aspect of the present invention, when the number of terminals simultaneously requesting random access among the plurality of user terminals is less than a predetermined threshold value, the information transmitting and receiving unit transmits the random access among a plurality of user terminals based on channel information of the terminal It is possible to determine the terminal that transmitted the requesting preamble.

According to another aspect, the sequence allocating unit dynamically controls a time period of a physical random access channel based on the number of user terminals requesting the random access, and the information transmitting / And can receive the sequence corresponding to the preamble through the random access channel.

According to another aspect of the present invention, the information transmitting and receiving unit may transmit the random access request to the user terminal after requesting a sequence corresponding to a preamble requesting the random access, And the sequence corresponding to the preamble can be received again from the user terminal.

According to embodiments of the present invention, by providing random access using compression sensing, even when a myriad of user terminals simultaneously request a connection to a base station in a wireless communication environment, the probability of collision between terminals due to multiple access is reduced, Thereby reducing the multiple connection processing delay time.

In addition, the present invention dynamically sets a period of a Physical Random Access Channel (PRACH), which is a channel for transmitting a preamble from a user terminal to a base station for a connection request, according to the number of users requesting connection, Time can be reduced.

1 is a diagram illustrating a plurality of user terminals belonging to a base station and a base station in an embodiment of the present invention.
2 is a diagram illustrating LTE random access control between a base station and a plurality of user terminals.
3 is a flowchart provided for explaining an operation of controlling random access using compression sensing, in an embodiment of the present invention.
4 is a block diagram showing a configuration of a random access control apparatus according to an embodiment of the present invention.
5 is a diagram illustrating a network environment in which random access between a base station and a plurality of user terminals is controlled using compression sensing, according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention relates to a technology for controlling random access using compression sensing. In particular, the present invention utilizes sequences for identifying user terminals using compression sensing rather than performing random access based on CSMA / CA, so that even if a large number of user terminals simultaneously request random access to a base station, To a technique for avoiding collision.

In addition, the present invention does not periodically use a physical random access channel (PRACH), which is a channel for transmitting a preamble, to request random access, but instead uses a PRACH To a technique for dynamically changing the period of a frame.

In embodiments of the present invention, a random access control apparatus that performs random access control using compression sensing so that collision between a plurality of user terminals requesting random access is reduced can be performed by the base station.

1 is a diagram illustrating a plurality of user terminals belonging to a base station and a base station in an embodiment of the present invention. 1, the base station 101 may represent a random access control apparatus.

Referring to FIG. 1, one base station 101 and N user terminals belonging to one base station 101 can configure a wireless network. In FIG. 1, it is assumed that random access control is performed in consideration of a case where K user terminals among N user terminals request a random access connection to the base station 101 at random.

Frequency Division Duplexing (FDD) The LTE network environment can be divided into uplink and downlink frequency bands. At this time, the physical random access channel (PRACH) is opened every predetermined period, and user terminals can transmit a random access request request to the base station 101 through the physical random access channel. For example, the base station 101 may transmit a physical random access channel (PRACH) to the N user terminals for every predetermined t _p subframe. Here, the physical random access channel (PRACH) has a length of one subframe on the time axis and a bandwidth of 1.08 MHz, that is, 839 subcarriers on the frequency axis.

로 랜덤 액세스 요청 의사가 발생하는 경우를 가정하면, 랜덤 액세스 요청 의사가 발생한 사용자 단말은 가장 가까운 물리 랜덤 액세스 채널(PRACH)에 프리앰블(Preamble)을 실어서 기지국(101)으로 전송함으로써, 해당 단말이 기지국(101)과의 접속을 희망한다는 의사를 전달할 수 있다. At this time, in each of the N user terminals,

The random access request intending user terminal transmits a preamble to the nearest physical random access channel (PRACH) and transmits the preamble to the base station 101, It is possible to transmit a wish to make a connection with the base station 101.

를 파라미터로 가지는 포아송 분포(Poisson distribution)로 표현될 수 있다. 즉, N개의 사용자 단말들 중 현재 시간(current time)에서 가장 가까운 시간에 해당하는 물리 랜덤 액세스 채널(PRACH, 103)을 통해 K개의 사용자 단말들이 동시에 랜덤 액세스 의사가 있음을 요청할 수 있다. 그러면, 기지국(101)은 랜덤 액세스 의사가 있음을 전달한 K개의 사용자 단말들(102)을 대상으로 자원 할당, RRC(Radio Resource Control) 연결 완료 메시지를 전송하는 등의 랜덤 액세스 제어를 수행할 수 있다.As shown in FIG. 1, when N user terminals participate in a network, the number of user terminals requesting random access via a specific physical random access channel (PRACH)

Can be expressed as a Poisson distribution having a parameter as a parameter. That is, the K user terminals can request simultaneous random access through the physical random access channel (PRACH) 103 corresponding to the closest time in the current time among the N user terminals. Then, the base station 101 can perform random access control such as resource allocation and RRC (Radio Resource Control) connection completion message transmission to the K user terminals 102 that have transmitted the random access request .

2 is a diagram illustrating LTE random access control between a base station and a plurality of user terminals.

2, in the LTE system, the random access may be configured in four steps (Steps 201 to 204 in FIG. 2).

In step 201, when at least one UE among a plurality of user equipment (UE) generates a random access request, the UE 210 generating a random access request transmits a random access preamble for a random access request To the base station (eNB) 220 via the physical random access channel (PRACH).

At this time, the user terminal 210 may select any one of a sequence set used in the entire network and use it as a preamble. For example, when a sequence set is constructed using an orthogonal sequence, there are 64 kinds of sequences available in the sequence set. For example, a Zadoff-Chu sequence can be used as an orthogonal sequence constituting a sequence set. When a Zadoff-Chu sequence is used, even if a plurality of user terminals select a same sequence as a preamble and request a random access, the base station 220 can know which sequence to use as a preamble, have. That is, the base station 2200 can identify what kind of preamble is used through the preamble transmitted from the user terminal 210.

In step 202, the base station 220 may transmit a random access response message to the user terminal 210 as the base station 220 identifies the type of preamble transmitted to the user terminal 210.

For example, when the type of the preamble is determined, the BS 220 can allocate resources for the preamble and instruct the user terminal 210 to send an RRC connection request to the allocated resources. In this case, when there are a plurality of user terminals that have transmitted a preamble, the base station 220 can allocate resources for a plurality of preambles, and transmits a random access response (Random Access Response Access Response) message. For example, the base station 220 may broadcast the random access response message to the N user terminals through a downlink channel.

In step 203, the N user terminals can receive the random access response message, and the user terminal 210, which has allocated resources for the preamble sent from the UEs receiving the random access response message, (220). ≪ / RTI > A UE that has not transmitted a preamble to the Node B 220 among the N user terminals may discard the random access response message.

In this case, when two or more user terminals select and use the same preamble, a case may occur in which a plurality of user terminals transmit their RRC connection requests to the base station 220 at the same time using the same allocated resources.

For example, when the user terminal 2 230 and the user terminal 3 240 transmit the first sequence to the base station 220 as a preamble, the user terminal 230 230 uses the same resources allocated to the first sequence, And the user terminal 3 (240) can transmit an RRC connection request to the base station 220. As described above, when two or more user terminals transmit an RRC connection request to the base station 220 using the same resource allocated to the common preamble, a connection collision may occur. The base station 220 may not receive the RRC connection request transmitted from the user terminal 2 230 and the user terminal 3 240 in a stable manner. Accordingly, in case of a connection collision, each of the user terminal 2 230 and the user terminal 3 240 may transmit the preamble again to the base station 220 after a predetermined backoff time. At this time, as described in step 201, each of the user terminal 2 230 and the user terminal 3 240 randomly selects a preamble among the 64 preambles used in the entire network and sends a random access request to the base station 220 Can be performed. If a connection collision does not occur, the RRC connection request transmitted from the user terminal 210 can be stably transmitted to the base station 203.

In step 204, the base station 220 may transmit an RRC connection completion message in response to the RRC connection request received from the user terminal 210. [ Upon receiving the RRC connection completion message at the user terminal 210, the random access procedure can be completed. That is, a communication session for transmitting and receiving data between the user terminal 210 and the base station 220 can be established upon receiving the RRC connection completion message.

In FIG. 2, when more than 30 user terminals among N user terminals simultaneously request random access to the base station 220, the probability of using the same preamble for a random access request may increase. That is, the probability of occurrence of a connection collision may increase, and consequently, a connection collision may increase the multiple connection delay time. Therefore, since the method of completing the connection according to the four steps (steps 201 to 204) described in FIG. 2 is inefficient in terms of delay, it is not possible to transmit the preamble, transmit the random access response message, The delay time can be reduced by compressing the third step (steps 201 to 203) into one step using compressed sensing.

FIG. 3 is a flowchart provided for explaining an operation of controlling random access using compression sensing according to an embodiment of the present invention, and FIG. 4 is a flowchart illustrating a configuration of a random access control apparatus according to an embodiment of the present invention. Fig.

3 may be performed by the matrix generation unit 401, the sequence assignment unit 402, and the information receiving unit 403, which are components of FIG. 3 and 4, the random access control operation can be performed by the random access control apparatus 400 corresponding to the base station to which the N user terminals belong.

When an orthogonal sequence, which is a kind of Zadoff-Chu sequence, is used as a preamble, the total number of usable preambles is limited. 3 and 4, the random access control apparatus 400 generates a sequence matrix for use as a preamble by using a non-orthogonal sequence rather than a Zadoff-Chu sequence, thereby reducing the number of usable frames . That is, a sequence matrix for distinguishing user terminals can be generated using a non-orthogonal sequence.

In step 301, the matrix generation unit 401 may generate a sequence matrix including non-orthogonal sequences for identifying each of a plurality of user terminals requesting multiple accesses.

를 가지고 있는 경우를 가정하면, 사용자 단말 K에서 기지국인 랜덤 액세스 제어 장치(400)까지의 채널은 h_k로 표현될 수 있다. 그러면, 행렬 생성부(401)는 비직교 시퀀스들을 이용하여 N개의 사용자 단말들 각각을 구분하기 위한 시퀀스 행렬을 생성할 수 있다. 예를 들어, 행렬 생성부(401)는 아래의 수학식 1과 같이, 839×N 크기의 시퀀스 행렬 A를 생성할 수 있다. For example, if the user terminal K of the N user terminals has a preamble sequence of length 839

The channel from the user terminal K to the random access control apparatus 400, which is a base station, can be represented by h _k . Then, the matrix generation unit 401 may generate a sequence matrix for distinguishing each of the N user terminals using non-orthogonal sequences. For example, the matrix generation unit 401 may generate a sequence matrix A of size 839 x N, as shown in Equation (1) below.

According to Equation (1), the sequence matrix A may include N preamble sequences in which a preamble sequence having a length of 839 is divided into N user terminals. Here, a sequence is divided for each column of the sequence matrix A, and a sequence for each column can be used to identify user terminals. For example, a sequence (S _{1,1 ...} S _1,839 ) corresponding to column 1 corresponds to sequence 1, and a sequence (S _{n, 1} ... S _{n, 839} ) corresponding to column n corresponds to sequence n .

In Equation (1), each vector constituting the sequence matrix A may follow a Gaussian distribution. For example, AK Fletcher, S. Rangan , and VK Goyal , "A sparsity detection framework for on-off random access channels," in Proc . IEEE ISIT, Seoul, Korea, Jun ./ Jul. 2009, pp. 169-173. [3] MJ Wainwright, "Sharp thresholds for high-dimensional and noisy sparsity recovery using l1-constrained quadratic programming," IEEE Trans. Inf . Theory, vol. 55, no. 5, pp. 2183-2202, May 2009. [4] JP Hong, W. Choi , BD . Rao , "Sparsity controlled random multiple access with compressed sensing," IEEE Trans. Wireless Communications, vol. 14, no. 2, pp. 998-1010, Feb. Referring to the compression sensing process of 2015 , the matrix generation unit 401 may generate each vector constituting the sequence matrix A as a random variable following a Gaussian distribution.

In step 302, the sequence assigning unit 402 may allocate a different sequence included in the sequence matrix to each of the plurality of user terminals.

For example, the sequence allocating unit 402 may allocate a column-by-column sequence constituting the sequence matrix A to N user terminals. For example, the sequence 1 (S _{1, 1} ... S _{1 , 839} ) is assigned to the user terminal 1, the sequence 2 (S _{2, 1} ... S _{2 , 839} ) is assigned to the user terminal 2, A different sequence may be assigned from user terminal 3 to user terminal N-1 and user terminal N may be assigned sequence n (S _{n, 1} ... S _{n, 839} ).

In step 303, the information receiving unit 403 may receive a sequence corresponding to a preamble requesting random access from at least one of a plurality of user terminals.

For example, the user terminal 1 to the user terminal? ₀ among the N user terminals allocated with different sequences included in the sequence matrix A may transmit a random access request to the random access control apparatus 400. [ Then, the signal y received by the random access control apparatus 400 can be expressed by the following equation (2).

In Equation (2), A is a sequence matrix, h * is a vector value as channel information indicating which user terminal transmitted a random access request preamble, w is a vector representing an Additive White Gaussian Noise (AWGN) Lt; / RTI >

According to Equation 2, when the value of the number of λ ₀ of the user terminal transmitting a random access request is less than a predefined threshold (e.g., threshold sparsity, k _max), the random access controller 400 is h * 1 Can be completely restored with a probability close to. Here, h * is a vector indicating whether or not a user terminal transmits a random access request preamble. Therefore, even if a user terminal transmits a random access request preamble using the same sequence, the random access control apparatus 400 determines, based on h * The user terminal that transmitted the preamble can be identified.

For example, when the value of h ₁ is 0, the information receiver 403 determines that the user terminal 1 has not transmitted the random access request preamble, and the value of h ₁ included in the received signal y is a value other than 0 , It can be determined that the user terminal 1 has transmitted the random access request preamble. In this way, at the same time each h * vector included if the λ ₀ of the user terminal for requesting a random access under the limit sparsity (k _max) predefined threshold, a random access control device 400 to the received signal y successfully to restore, a λ ₀ transmits a random access request preamble sequence by the same one can distinguish the user terminals (λ ₀ <k _max). That is, the LTE random access procedure (steps 201 to 203 in FIG. 2) can be reduced to one step. Since the vectors constituting the sequence matrix A are random variables following the Gaussian distribution, the random access control apparatus 400 can successfully restore each h * vector included in the received signal y .

At this time, a predetermined sparsity (k _max ), which is a predetermined threshold value in relation to the number of user terminals λ ₀ for simultaneously requesting random access, can be defined as Equation 3 below.

In Equation (3), reference numeral 839 denotes a sequence length, k _max denotes a maximum number by which the random access control apparatus separates user terminals, and n denotes a network total user terminal number.

According to Equation (3), when? ₀ is not a natural number equal to or greater than 45, that is, a natural number less than 45, the random access control apparatus 400 can successfully restore each h * vector included in the received signal y. Since the physical random access channel (PRACH) is opened every predetermined period (e.g., several milliseconds), the present invention can be applied to an MMTC (massive machine type communication) system in which a large number of user terminals Even if the network environment is assumed, it is very unlikely that more than 45 user terminals continuously request random access on each physical random access channel (PRACH), thereby providing stable random access. That is, the random access control apparatus 400 can always perform random access to the maximum number of user terminals available in the LTE system.

In step 304, the information receiving unit 403 may transmit a message to the corresponding terminal indicating that the random access is completed based on the sequence received from at least one of the plurality of user terminals.

For example, as described above, the information receiving unit 403 receives the channel information h *, which is used when the user terminal transmits a pre-allocated sequence from the sequence allocating unit 402, It is possible to determine at least one terminal that transmitted the random access request preamble among the terminals. Then, the information receiving unit 403 can transmit an RRC connection setup message to the determined at least one user terminal.

On the other hand, if the random access control apparatus 400 can not successfully recover the h * and can not determine the user terminal that transmitted the random access preamble in step 303, the corresponding user terminal sets the predetermined backoff time the random access preamble may be transmitted to the random access control apparatus 400 through the nearest physical random access channel (PRACH). For example, when the value of? ₀ is 45 or more, it may happen that the user terminal that transmitted the random access preamble can not be determined. Then, the user terminal having a connection collision may request the random access by transmitting the sequence allocated from the random access control apparatus 400 as the random access preamble to the random access control apparatus 400 again after the backoff time has elapsed. The random access request may be periodically performed until the random access is successful, i.e., every predetermined back-off time until the RRC connection establishment message is received.

5 is a diagram illustrating a network environment in which random access between a base station and a plurality of user terminals is controlled using compression sensing, according to an embodiment of the present invention.

According to FIG. 5, one base station 501 and N user terminals can form a network. At this time, N sequences corresponding to each column constituting the sequence matrix A generated based on the compression sensing may be allocated to each of the N user terminals.

Then, the user terminal 502 which has generated the random access request transmits a preamble through the physical random access channel (PRACH) to the base station 501, and transmits a random access response for requesting the RRC connection to the resource allocated to the preamble (PRACH) as a random access preamble from the base station 501 in place of the three-step process of receiving the RRC connection request and transmitting the RRC connection request to the base station 501 have. That is, the preamble transmission, the random access response, and the RRC connection request can be performed by one process instead of the above-described three-step process. The base station 501 can transmit an RRC connection setup message to the user terminal 502 based on the channel information h * included in the received signal.

At this time, if the base station 501 can not successfully recover the h * and can not determine the user terminal 502 that transmitted the random access preamble, the corresponding user terminal 502 transmits a predetermined backoff time, The random access preamble may be transmitted to the base station 501 through the physical random access channel (PRACH) again. Here, the physical random access channel (PRACH) is not opened every predetermined fixed time period but is controlled to be adaptively opened according to the number of user terminals (including the frequency number of user terminals requesting random access) . The operation of dynamically allocating the physical random access channel (PRACH) can be performed by the sequence assigning unit 402 in Fig.

For example, if the base station 501 over one of the physical random access channel number of the user terminal requests the random access through the (PRACH) (λ ₀₎ is predefined threshold value of the (k _max), Physical Random Access Channel ( (PRACH) to be opened is shorter than the time period in which the physical random access channel (PRACH) was opened immediately before and the number (? ₀ ) of user terminals requesting random access through one physical random access channel If it is less than predefined threshold value (k _max), the time period may be of the physical random access channel (PRACH) to be controlled so as to increase than the time period set for the physical random access channel (PRACH) on the verge.

That is, the base station 501 is λ ₀ of request for a physical random if the access channel (PRACH) is less than the number of the user terminal requesting a random access (λ ₀₎ is a threshold value (k _max) predefined in through a random access And can perform scheduling for random access to all user terminals. Accordingly, the base station 501 is the time period that the PRACH channels will open, depending on the particular physical random access number of the user terminal requesting a random access through a channel (PRACH) (λ ₀₎ and a predefined threshold value (k _max) It can be dynamically controlled to increase or decrease. In other words, if the number (? ₀ ) of user terminals is greater than or equal to a predetermined threshold value ( _kmax ), the PRACH channel is frequently opened so that the number (? ₀ ) of user terminals requesting random access through a specific PRACH is (K _max ), and if the number (? ₀ ) of user terminals is less than a predetermined threshold value (k _max ), the PRACH channel is controlled to be opened slowly so that frequency resources can be efficiently used have.

For example, the base station 501 can dynamically control the time period t _p of the PRACH based on Equation (4) below.

In Equation (4), t _p represents a time period in which the physical random access channel (PRACH) is opened, k _max is a predetermined threshold value, and λ ₀ is the number of random access requests in the user terminal .

The base station 501 can dynamically control the time period of the physical random access channel (PRACH) according to Equation (4) above, thereby reducing the waste of frequency resources generated when the PRACH is opened unnecessarily frequently. It is possible to reduce the back-off delay time due to the connection collision that occurs when the user is spatially open.

As described above, the random access control apparatus and method according to the present invention perform random access using non-orthogonal sequences generated using compression sensing, thereby lowering the collision probability to be lower than that of the LTE system, Time can be reduced. In addition, the access delay time can be reduced by dynamically controlling the time period in which the PRACH for the preamble transmission is opened in the user terminal according to the ratio of the number of user terminals that are willing to randomly access among the N total user terminals.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, controller, arithmetic logic unit (ALU), digital signal processor, microcomputer, field programmable array (FPA) A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing apparatus may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

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. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI &gt; or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (14)

A method for controlling random access using a plurality of user terminals belonging to a base station using compression sensing,
Generating a sequence matrix including non-orthogonal sequences for identifying each of a plurality of user terminals requesting a multiple access;
Assigning a different sequence included in the sequence matrix to each of the plurality of user terminals;
Receiving a sequence corresponding to a preamble requesting random access from at least one terminal among the plurality of user terminals; And
Transmitting a message indicating that the random access is completed to the user terminal requesting the random access based on the received sequence
The random access control method comprising: The method according to claim 1,
Wherein the assigning of the different sequences included in the sequence matrix comprises:
Assigning a sequence for each column among the sequences included in the sequence matrix to each user terminal
And a random access control method using the compression sensing. The method according to claim 1,
Wherein the step of transmitting a message indicating that the random access is completed comprises:
If the number of terminals requesting random access at the same time is less than a predetermined threshold value, the terminal that transmitted the preamble requesting the random access among the plurality of user terminals is determined based on the channel information of the terminal that
And a random access control method using the compression sensing. The method according to claim 1,
Each vector included in the sequence matrix is a random variable following a Gaussian distribution
And a random access control method using the compression sensing. The method according to claim 1,
The message indicating that the random access is completed,
RRC connection setup (Radio Resource Control Connection Setup) message
And a random access control method using the compression sensing. The method according to claim 1,
Wherein the assigning of the different sequences included in the sequence matrix comprises:
A time period of a physical random access channel is dynamically controlled based on the number of user terminals requesting the random access,
Wherein the step of receiving the sequence corresponding to the preamble comprises:
And receiving a sequence corresponding to the preamble through the physical random access channel
And a random access control method using the compression sensing. The method according to claim 1,
Wherein the step of receiving the sequence corresponding to the preamble requesting the random access comprises:
When a connection collision occurs in a user terminal requesting a sequence corresponding to a preamble requesting the random access, a sequence corresponding to the preamble is re-transmitted from the corresponding user terminal after a predetermined backoff time Receiving
And a random access control method using the compression sensing. A random access control apparatus for controlling random access using a plurality of user terminals using compression sensing,
A matrix generator for generating a sequence matrix including non-orthogonal sequences for identifying each of a plurality of user terminals requesting a multiple access;
A sequence allocator for allocating different sequences included in the sequence matrix to each of the plurality of user terminals; And
Receiving a sequence corresponding to a preamble requesting random access from at least one terminal of the plurality of user terminals and transmitting a message indicating that random access is completed to a user terminal requesting random access based on the received sequence The information transmission /
The random access control apparatus comprising: 9. The method of claim 8,
Wherein the sequence allocator includes:
Assigning a sequence for each column among the sequences included in the sequence matrix to each user terminal
And a random access control device using the compression sense. 9. The method of claim 8,
The information transmission /
If the number of terminals requesting random access at the same time is less than a predetermined threshold value, the terminal that transmitted the preamble requesting the random access among the plurality of user terminals is determined based on the channel information of the terminal that
And a random access control device using the compression sense. 9. The method of claim 8,
Each vector included in the sequence matrix is a random variable following a Gaussian distribution
And a random access control device using the compression sense. 9. The method of claim 8,
The message indicating that the random access is completed,
RRC connection setup (Radio Resource Control Connection Setup) message
And a random access control device using the compression sense. 9. The method of claim 8,
Wherein the sequence allocator includes:
A time period of a physical random access channel is dynamically controlled based on the number of user terminals requesting the random access,
The information transmission /
And receiving a sequence corresponding to the preamble through the physical random access channel
And a random access control device using the compression sense. 9. The method of claim 8,
The information transmission /
When a connection collision occurs in a user terminal requesting a sequence corresponding to a preamble requesting the random access, a sequence corresponding to the preamble is re-transmitted from the corresponding user terminal after a predetermined backoff time Receiving
And a random access control device using the compression sense.

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