KR20080013349A - Method and apparatus for transmitting and receiving signal in communication system, and channel structure used in the same - Google Patents

Abstract

A method and an apparatus for transmitting and receiving signals in a communication system and a channel structure for the same are provided to receive RACH(Random Access Channel) signals from UE(User Equipments) more efficiently by distributing RACH slots to UEs efficiently. The power of a UE is turned on(S1101), the UE executes cell searching and uplink synchronization(S1102). Also the UE acquires an uplink structure, and identifies an RACH(S1103). Then, using the total RACH length allocated in the present cell, the UE executes initial access(S1104). If a response signal is received from a base station through the initial access, the UE measures the distance from the base station by comparing uplink synchronization information with downlink synchronization information using the received signal(S1105). Based on the measured distance information, the UE selects a proper length among the total RACH length(S1106). Using the selected length, the UE executes random access(S1107).

Description

Method and Apparatus for Transmitting and Receiving Signal in Communication System, and Channel Structure Used in Them {Method and Apparatus for Transmitting and Receiving Signal In Communication System, And Channel Structure Used In The Same}

1 and 2 illustrate an example of a process that occurs when a terminal connects uplink communication with a base station.

3 illustrates the structure of a RACH signal used for synchronous and asynchronous connections.

4 is a diagram for explaining a cell size and a channel length.

5 is a diagram illustrating a case where the same sequence is repeated to form a long length channel signal and a case where a different sequence is defined according to each length.

6 is a diagram for explaining a basic structure for forming a channel signal.

7 is a view for explaining a method of forming a channel structure in a large cell through the basic structure shown in FIG.

8 is a diagram for describing a phenomenon occurring according to a distance between each user equipment (UE) and a base station in a large cell.

9 illustrates a method of newly defining a channel signal according to the position of a UE in a cell according to one embodiment of the present invention.

FIG. 10 is a diagram for explaining a method of allocating communication resources to a plurality of UEs by using a newly defined channel signal according to a location of a UE in a cell according to one embodiment of the present invention; FIG.

FIG. 11 is a flow chart illustrating a method of forming a channel signal based on a location of a UE within a cell in accordance with an embodiment of the present invention. FIG.

12 is a block diagram illustrating a configuration of a UE and a channel former included therein to form a channel signal based on the position of the UE in a cell according to one embodiment of the present invention;

FIG. 13 is a block diagram illustrating a characteristic configuration of a base station for receiving channel signals from the UE and allocating resources based on the location of the UE in the cell in accordance with one embodiment of the present invention. FIG.

FIG. 14 is a diagram for describing a method of forming a channel signal when a channel signal is retransmitted because there is no response from a base station for random access of a UE according to one embodiment of the present invention; FIG.

15 is a flowchart illustrating a method of forming a channel signal when a channel signal is retransmitted because there is no response from a base station to a random access of a UE according to an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication technology, and more particularly, to a signal transmission and reception method, an apparatus, and a channel structure used in the communication system.

The uplink channel of the communication system currently being discussed includes a random access channel (RACH) for random access by a user equipment to a base station, and an uplink shared channel for transmitting channel quality indicator (CQI) and ACK / NACK information (eg, For example, HS-DPCCH). Among them, the RACH is a random access channel where the UE performs downlink synchronization with the base station and can be found through the base station information. The location of the channel and the like can be known from the base station information, and the RACH is the only channel accessible by the terminal in synchronization with the base station. When the terminal transmits a signal to the corresponding base station through the RACH, the base station informs the terminal of the modified information on the uplink signal timing in order to synchronize with the base station itself, and various kinds of information for connecting the terminal to the base station. After the connection between the terminal and the base station is performed through the RACH, communication may be performed using another uplink channel.

1 and 2 illustrate an example of a process that occurs when a terminal connects uplink communication with a base station.

By accessing the RACH, the UE can acquire synchronization of both the base station and the uplink / downlink, and the terminal can be accessed. 1 illustrates a situation when a terminal is powered on and connected to a base station for the first time, and FIG. 2 illustrates that after the terminal synchronizes with an initial base station, the synchronization is out of sync or a request for an uplink resource is required. Case (i.e., requesting resources for uplink transmission data). The base station finds out what purpose the UE has approached the RACH and takes a corresponding process. In approaching the RACH, FIG. 2 may use different signals depending on whether the signal sent to the RACH is synchronized with the base station. In the case of synchronous access (synchronized access), after the UE performs synchronization with the base station, the RACH is performed in a situation where synchronization is maintained (synchronization can be maintained through control information such as a downlink signal or a CQ pilot transmitted on uplink). By accessing, the base station can easily recognize the signal included in the RACH. Since the synchronization is maintained, the terminal can use a longer sequence or transmit additional data. On the other hand, in the case of non-synchronized access, when the terminal approaches the base station, and if the synchronization is not synchronized for some reason, the guard time must be set in accessing the RACH. This guard time is set in consideration of the maximum round-trip delay that a terminal wishing to receive service in the base station may have.

3 is a diagram illustrating a RACH signal structure used for a synchronous connection and an asynchronous connection.

The length of the RACH should vary according to the cell size of the base station. The farther the terminal is from the base station, the greater the round trip delay, which means that the protection time that must be set for the terminal in the asynchronous connection is longer. In addition, when the cell size increases, a path loss between the terminal and the base station becomes large, and thus a signal needs to be spread and transmitted longer. This situation is shown in FIG.

4 is a diagram for describing the size of a cell and the length of a channel.

As shown in Fig. 4, the length of the channel, in particular the length of the RACH, is set in proportion to the cell size where the actual communication system is to be installed. How to transmit the actual RACH signal for these different RACH lengths are currently classified into two types in 3GPP LTE. One method is to increase the signal length by simply repeating the RACH signal to be provided by the smallest cell when the cell size is increased, and the other is to define different sequences for channels of different lengths. Let's do it. If the signal of the smallest cell is used repeatedly, the terminal has the advantage of being as simple as that. On the other hand, in using a longer length RACH, since a short sequence is repeatedly used, a usable random access sequence may be reduced. On the other hand, when each long sequence is defined and used, there is an advantage that the base station can use better detection performance and a larger number of random access sequences. Of course, the complexity of the terminal is slightly increased.

5 is a diagram illustrating a case where the same sequence is repeated to form a long length channel signal and a case where a different sequence is defined according to each length.

FIG. 5 illustrates a case where the same sequence is repeated at the top and a case where different sequences are defined at the bottom when the long channel signal is to be formed in the large cell as described above.

As described above, when the cell radius is increased, the length of the channel is generally long, and in the case of the RACH, which must increase the spreading factor and the guard time of the applied sequence due to the path loss and the increase in the round trip delay. The terminal accessing the longer channel generates a sequence signal for accessing the base station through the corresponding channel and transmits it to the assigned channel position. However, as described above, when the cell radius increases, it is preferable that a terminal far from the base station uses a long channel due to a path loss and a round trip delay to the base station. On the other hand, if the terminal is located close to the base station in the same cell, the entire long channel is unnecessarily long for the terminal. Therefore, a technique for performing efficient resource management based on the location between the base station and the terminal is required.

An object of the present invention to solve the above problems is to provide a method and apparatus for performing efficient resource management by determining the length of the channel used by the UE based on the location information in the cell of the UE.

Another object of the present invention is to provide a method and apparatus for increasing detection performance for retransmission by increasing the length of a channel retransmitting when there is no response from a base station for a UE's random access.

A signal transmission method according to an embodiment of the present invention for achieving the above object is a signal transmission method of a user equipment in a communication system, which is used for connection with a base station of the entire channel length based on the location information in the cell of the user equipment. Selecting a length; And transmitting a channel signal having the selected length.

In this case, the communication system may be a communication system that increases the overall channel length in proportion to the cell radius.

The channel may be a random access channel, and the location information in the cell of the user equipment may include: an initial access step of accessing the base station using the entire length of the random access channel; And determining the location in the cell of the user equipment through the signal received from the base station in response to the initiation connection, and storing the determined location information in the cell. It may further include.

In addition, the location determining step may determine the location in the cell of the user equipment by comparing the information received from the base station in response to the initiating connection and the information transmitted when the initiating connection to the base station, May be performed when the user device is powered on.

The length selecting step may select a length to be used for the connection in consideration of a path loss and a round trip delay based on the position information, and select a position at which signals having the length selected in the length selecting step are inserted in the entire channel. The method may further include determining.

On the other hand, in the above-described embodiment, when there is no response from the base station to the transmission in the transmission step, the transmission power of the selected length and / or channel can be increased.

A signal transmission method according to another embodiment of the present invention is a signal transmission method of a user equipment in a communication system, which increases a spreading factor of a sequence inserted into a channel in proportion to a distance between the user equipment and a base station in a cell. step; And applying the spread sequence to the channel and transmitting.

On the other hand, the signal transmission method according to another embodiment of the present invention is a signal transmission method of the user equipment in the communication system, the number of repetitions of the sequence inserted into the channel in proportion to the distance between the user equipment and the base station in the cell Increasing; And applying the repeated sequence to the channel and transmitting.

In addition, a resource allocation method according to another embodiment of the present invention is a resource allocation method of a base station in a communication system, and determines a channel length to be used by the user equipment among all channel lengths based on location information in a cell of a predetermined user equipment. Doing; And allocating a position of a portion of the entire channels having a channel length for use by the user device.

In this case, the channel includes an uplink shared channel, and location information in a cell of the user device may be obtained through an initial access using a random access channel of the user device.

On the other hand, the signal reception method according to another embodiment of the present invention is a signal reception method of a base station in a communication system, each of which is used by the plurality of user equipment based on the location information in the cell of a plurality of user equipment in a cell Determining a channel length; Allocating positions of portions of the entire channels each having a channel length for use by the plurality of user devices; And receiving signals from the plurality of user devices from the assigned location.

On the other hand, the random access channel structure according to another embodiment of the present invention is a random access channel structure to the communication system to increase the length of the allowed random channel in proportion to the cell radius, the location of the user equipment in the cell The random access channel signal having a length selected based on the information is inserted in a predetermined position among all of the allowed random access channels.

A channel former according to another embodiment of the present invention is a channel former of a user equipment in a communication system, and selects a length to be used for connection with a base station among all channel lengths based on location information in a cell of the user equipment. A selection unit; A position determiner configured to determine a position at which the channel signal having the length selected by the length selector is inserted in the entire channel; And a sequence applying unit applying a sequence to a channel based on the selected length and the position information to be inserted.

In this case, the channel may be a random access channel, and the channel former may include: a receiver receiving a signal received from the base station in response to an initiating connection for accessing the base station using the full length of the random access channel; An in-cell position determination unit for determining a position in the cell of the user equipment through the signal received by the receiver; And a memory for storing the determined in-cell location information.

Lastly, a base station according to another embodiment of the present invention is a base station in a communication system that increases the length of a permitted channel in proportion to a cell radius, and provides a start access signal through a random access channel of a user equipment in the cell. A position determining unit which receives and acquires position information in the cell of the user equipment; And a resource allocator configured to allocate uplink shared channel resources of the user device based on the location information obtained by the location determiner.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one of ordinary skill in the art appreciates that the present invention may be practiced without these specific details. In some instances, well-known structures and devices are omitted or shown in block diagram form, centering on the core functions of each structure and device, in order to avoid obscuring the concepts of the present invention. In addition, the same components will be described with the same reference numerals throughout the present specification.

The present invention proposes a method for efficiently using a channel when a cell radius is large in a mobile communication system, in particular, an RACH used for uplink synchronization. That is, the amount of resources of the channel also increases according to the cell radius, but this is useful for terminals far away from the base station, but unnecessarily high resources for terminals close to the base station. Therefore, when the cell radius is large, the channel structure and the channel signal design for more effective use of the channel are performed.

There are two issues with using channels. One is how to use the signal used for the channel and how to implement the structure of the channel.

6 is a diagram for describing a basic structure for forming a channel signal.

In structure 601, referred to as "Basic Sequence only" at the top of FIG. 6, it is simply like a sequence on the channel (e.g., in CAZAC, such as GCL CAZAC and Zadoff-Chu CAZAC, WCDMA mainly used in 3GPP). In some cases, a signal generated from a commonly used gold code, etc., may be directly inserted to communicate. In particular, power boosting is easy due to a certain size among the above-described examples, and a brief description of a CAZAC sequence which is advantageous in synchronizing acquisition due to excellent correlation characteristics is as follows.

Two kinds of CAZAC sequences are used, which are GCL CAZAC and Zadoff-Chu CAZAC as described above. The relationship between these two types is tied together by a conjugate complex relationship, so Zadoff-Chu CAZAC is obtained by applying the conjugate complex operation to the GCL CAZAC. Zadoff-Chu CAZAC is given by

Here k denotes a sequence index, N denotes a length of a CAZAC sequence to be generated, and M denotes a sequence ID.

When the Zadoff-Chu CAZAC sequence given by Equation 1 and Equation 2 and the GCL CAZAC sequence in a conjugate complex relationship thereof are represented by c (k; N, M), all three characteristics are as follows.

Equation 3 shows that a CAZAC sequence always has a size of 1, and Equation 4 shows that an auto-correlation function of a CAZAC sequence is represented as a delta function. Here autocorrelation is based on circular correlation. In addition, Equation 5 shows that the cross-correlation is always constant.

As shown in Equation 3, the size of the signal transmitted through the channel is constant, thereby providing an advantage of sufficiently boosting the time-domain signal at the transmitter as described above. In addition, in the case of Equation 4, when the terminal detects a sequence from the channel, the base station provides a basis for finding an accurate time synchronization, and the last Equation 5 is characterized by each base station when the channels of several base stations are mixed together. It can be effectively handled in differentiation.

The structure 601 shown at the top of FIG. 6 illustrates a structure in which various sequences including the CAZAC sequence are simply inserted into a channel without a cyclic prefix or a repeating structure. In this case, a repetition or a cyclic prefix such as the structure 602 referred to as "Basic CP only" or the structure 603 referred to as "Basic CP + Repetition" will not be used. Since the transmission signal itself can be sent the longest, and thus can transmit the most information in the RACH. However, since there is no repeating structure like the structure 603, in order to detect a signal, it is necessary to check whether there is a signal for all time delays. This is a disadvantage that can give a lot of load to the base station. In addition, although it depends on the signal length, it is not tolerated that an error occurs in detecting the RACH signal at the base station (receiving end) when the cyclic prefixes such as the structures 602 and 603 are not used. As such, the structure 601 which does not include the cyclic prefix has a timing error when the base station (receiver) detects the RACH signal when channel distortion such as multipath occurs, and if the signal is carried on the OFDM subcarrier, OFDM As the orthogonally of the signal is broken, there is a problem in detecting the signal itself at the receiving end.

For use in such a multipath environment, a cyclic prefix (CP) is placed at the front of the signal, such as the structure 602 referred to as "Basic CP only" at the interruption of FIG. Make it tough. In this case, the receiver can ignore the time error caused by the multipath, but there is still a problem that the signal detection should be performed for all the delay time positions.

If it is unreasonable or not possible to detect the signal at all positions, the channel signal itself has a repetitive structure, such as structure 603, referred to as " Basic CP + Repetition " at the bottom of FIG. There may be a case where a circulating anterior portion is inserted into the. In this way, the receiving end receiving the RACH signal or the like can detect timing based on autocorrelation with respect to the received signal. It is not necessary to know what the signal is, as it is necessary to detect the timing by cross-correlation as shown in Equation 5, and since a processing other than autocorrelation is not necessary, a very good technique for detecting the timing at the receiving end is required. do. However, since the length of the signal is shortened due to the repetitive structure, the amount of information that can be sent is reduced.

6 is a channel signal structure used to access a channel of a basic unit supported by the system. In contrast, when a channel length needs to be extended, it may be extended in various ways as follows.

FIG. 7 is a diagram for describing a method of forming a channel structure in a large cell through the basic structure shown in FIG. 6.

Hereinafter, the RACH will be described as an example. The basic frame is extended for each frame of FIG. 6, and the method is to repeat the basic sequence and regenerate for a new length without repeating. That is, if the "Basic Sequence only (601)" case where only a signal such as a CAZAC sequence exists without a cyclic prefix and a repetition structure is extended to apply to a RACH of three times length, the sequence is simply repeated three times and tripled in length. There is one method of transmitting to the RACH through the structure of 701a of the structures referred to as "Extended Sequence only", and the other is tripled without repeating the basic sequence as shown by structure 701b. This is a way to create one long sequence by redefining the sequence as long as it can be used in the extension. This is shown in Fig. 7A.

In case of "Basic CP only (602)", it can be extended in a similar manner, except for the first CP, such as structure 702a, and transmitting the rest three times repeatedly, or up to CP as structure 702b. Signals may be generated using simple repetition, or a long sequence such as structure 702c may be applied to the front of CP. This structure is shown in Fig. 7B.

Similarly, the case of "Basic CP + Repetition (603)" may be applied. In this case, a sequence having an original repeating structure, such as structure 703a, is repeated except for CP to generate a long sequence, or a structure 703b. It is possible to generate a long sequence by repeating including a CP, or a long sequence having a repeating structure, such as structure 703c, and attaching and transmitting a CP. If the RACH signal is extended as shown in (c) of FIG. 7 by the above methods, the UE accesses the extended RACH as an extension sequence, so that UEs far from the base station may be located despite path loss and round trip delay. By performing communication with the base station can be uplink synchronization.

FIG. 8 is a diagram for describing a phenomenon occurring according to a distance between each UE and a base station in a large cell.

8 illustrates, for example, UE3 at the edge of the cell supported by the base station, UE2 in the middle of the cell, and UE1 near the base station. 8 shows path losses of these UE1, UE2, and UE3 as L _p ¹ , L _p ² , and L _p ³ , respectively, and the round trip delays are represented by 2t _d ¹ , 2t _d ² , and 2t _d ³ . Here, 2t _d ¹ , 2t _d ² , and 2t _d ³ indicate that the round trip delay is ^twice the delay t _d ¹ , t _d ² , and t _d ³ , respectively, for one-way transmission. Usually there are path losses in distant order, L _p ¹ <L _p ² <L _p ³ , round trip delay likewise 2t _d ¹ <2t _d ² <2t _d ³ . Accordingly, the lengths of the guard intervals G _d ¹ , G _d ² , and G _d ³ required according to the positions of UE1, UE2, and UE3 in the cell become G _d ¹ <G _d ² <G _d ³ , and are applicable to the channel. Expansion coefficients S _p ¹ , S _p ² , and S _p ³ of the sequence are also S _p ¹ <S _p ² <S _p ^{3 has} a relationship. That is, in case of UE3, the RACH must be approached with a sequence having a long RACH and a high spreading coefficient to obtain the performance equivalent to that obtained when UE1 approaches the RACH with a shorter RACH and a lower spreading coefficient. . However, in case of UE1, the RACH allocated by the base station is used, but when the cell radius is large, the size of the RACH is designed according to the condition for supporting the edge UE (eg, UE3) of the cell. Therefore, in the case of the terminal near the base station, such as UE1, such a situation in which such a long RACH is not necessary actually occurs.

FIG. 9 is a diagram for explaining a method of newly defining an RACH signal according to a position of a UE in a cell according to one embodiment of the present invention.

In the communication system that increases the length of the RACH allowed in proportion to the radius of the cell as described above, in order for each UE to efficiently perform random access, each UE is allowed in the cell based on its own cell location information. Selecting an appropriate length from the length of the RACH, and applying a sequence having this length to the RACH and transmitting compared to using a RACH having a length to support all UEs in the cell all located at the cell boundary Efficient Specifically, in the case of "Nearby UEs" having a close distance to the base station even in a large cell, by using only a part of the total RACH lengths allowed as shown in FIG. 9, each UE may randomly access the base station. ) Can be increased, and also, since random slots to which each UE can be randomly increased increase the probability of collision of random accesses of respective UEs as a whole. In addition, as will be described in more detail below, the random access failure probability may be increased by increasing the length of the sequence to be applied within the RACH length allowed when retransmitting the RACH signal according to the random access failure to the base station. Meanwhile, those skilled in the art can recognize that the scheme of using only a specific portion of the entire channel length based on the position of the UE as shown in FIG. 9 may be applied to other uplink channels other than the RACH. Hereinafter, the above-described principle will be described in detail using the case where UE1, UE2, and UE3 shown in FIG. 8 use RACH.

According to one embodiment of the present invention as described above, UE1, UE2, UE3 shown in FIG. 8 takes a method of approaching different RACH according to the situation that the UE belongs to each other. First, since all UEs initially do not know the distance between the UE and the base station at all, and how much the path loss is, the initial access is common to all UEs in the cell depending on the cell size. The base station is accessed using the total length allocated by. After this approach, the base station transmits uplink synchronization information to the mobile station to the mobile station, and the mobile station can determine the location in its cell by using the synchronization difference between the downlink signal and the uplink signal.

The UE1, UE2, and UE3 having their own location as described above may interpret the RACH differently as shown in FIG. 9 based on their own location information in random access for accessing the RACH again after the initial access. In other words, if the UE is far from the base station, it selects a repeating unit of the minimum unit sequence or selects a sequence having a corresponding length using all allocated RACHs as one unit (in case of UE3), and when the UE is very close to the base station, no long RACH is needed. In the RACH, the RACH is divided into the smallest units and the minimum unit sequence is applied to only one of them. 9 illustrates a case where "Nearby UEs" is UE1 and an extended RACH is three times the basic minimum unit RACH. In this case, the position where the sequence having the selected length is inserted among the entire RACHs may be generally selected by UE1 due to the characteristics of the RACH. However, the position to which the sequence is applied is controlled according to a predetermined method in terms of efficient management of resources. May be In the case of the UE2 at an intermediate distance, the RACH signal having a length selected based on its own cell location information, for example, a sequence corresponding to 2/3 of the total RACH length, is transmitted by using the RACH.

As such, the RACH structure used in accordance with an embodiment of the present invention in a communication system that increases the length of an RACH that is allowed in proportion to the cell radius is such that an RACH signal having a length selected based on the location information in the cell of the UE is total. It has a structure inserted in a predetermined position of the RACH.

In the above-described example, selecting a length to which a sequence is applied among all RACHs for each UE, and which part of the allowed RACHs to insert a sequence having a length selected for each UE is determined for each UE by the characteristics of the RACH as described above. It is common to choose arbitrarily. However, after acquiring the location information of the UE of the UE through the initiation connection through the RACH, an uplink for transmitting control information of another uplink channel (eg, CQI, ACK / NACK, etc.) except for the RACH. Selecting a channel length to be used by the UE out of the total length of the shared channel, and determining the position where this length portion is inserted in the entire channel may be performed by the base station in terms of efficient management of resources.

Accordingly, in another embodiment of the present invention, as in the above-described embodiment, slots to be used for a channel are increased as in the case of using only a partial length of all channels allocated to all UEs in a cell based on location information in each cell for each UE. In this case, the base station also proposes a scheme in which the base station allocates uplink resources of each UE, that is, resources to be used for random access of each UE after the initiation access using the RACH.

FIG. 10 is a diagram for describing a method of allocating communication resources to a plurality of UEs by using a newly defined RACH signal according to a location of a UE in a cell according to one embodiment of the present invention.

In a communication system that increases the length of a random access channel that is allowed in proportion to a cell radius, a base station according to an embodiment of the present invention receives initiation access signals of UEs to obtain location information of each UE. Here, the base station obtaining location information of each UE may be obtained by comparing the synchronization information obtained through the initiation access signal transmitted from the UEs with the synchronization information of the signal transmitted by the base station in response to the initiation access signal. . The base station may allocate uplink resources of the UEs based on the location information in the cells of the UEs acquired as described above. Specifically, as illustrated in FIG. 10, UEs having a close distance to the base station in the same cell (UE1a, UE1b, and UE1c) can maintain a level of performance equivalent to that of remote UEs using the entire RACH even when using only a portion of the entire RACH, for example, 1/3 of the length in FIG. Each of them may be allocated to perform random access through one part of the three-part divided total RACH length. The resource allocation of the base station may be performed for the RACH signal used in the random access step as shown in FIG. 2 after confirming the location information through the initial access as shown in FIG. 1, or by a separate allocation step. May be That is, the resource allocation method according to an embodiment of the present invention is a method in which the base station determines the length of each UE to apply the actual sequence of the entire RACH and the position to apply the sequence, based on the location information in the cells of the UEs. Through such resource allocation, the base station can efficiently receive random access signals from a plurality of users without collision.

A method of performing embodiments of the present invention as described above is described in more detail below.

FIG. 11 is a flowchart illustrating a method of forming an RACH signal based on a location of a UE in a cell according to one embodiment of the present invention.

In step S1101, if a complete synchronization with the base station is lost, such as when the UE is powered on, the UE performs cell discovery and downlink synchronization through steps S1102 and S1103, and then obtains an uplink structure and Identifies the RACH according. Then, in step S1104, the UE performs the initiation connection using all the allocated total RACH lengths in its cell. When receiving a response signal from the base station through the initiating connection, the UE performs a process of comparing the uplink synchronization information and the downlink synchronization information from the received signal, and thereby measures the distance to the base station in step S1105. Thereafter, based on the positional information obtained in step S1105, in step S1106 a length to be used is selected by applying a sequence among all RACHs. That is, by splitting the RACH into units determined to be sufficient length for service and randomly selecting one of them, if the distance from the base station is far, it is decided to use all the RACH lengths and the distance from the base station is close. In this case, it is decided to use only a part of the allocated total RACH. With the length information thus determined, in step S1107, the UE performs random access through the RACH length specified for each UE. Of course, the base station should use a signal detection algorithm in the RACH in consideration of such a situation.

A configuration of a channel former and a base station for performing the method according to the embodiments of the present invention described above are as follows.

12 is a block diagram illustrating a configuration of a UE and a channel former included in the RACH signal based on the position of the UE in the cell according to an embodiment of the present invention.

In a communication system that increases the length of a random access channel that is allowed in proportion to the cell radius, the channel former of the UE according to an embodiment of the present invention includes a length selector 1204 and a sequence application position determiner 1205. The length selector 1204 for selecting the actual length to be used among the RACHs selects the length to be used for random access between the base station among the allowed RACH lengths based on the location information of the UE, that is, the distance between the base station and the corresponding UE. . In this case, in case of a UE that is close to the base station, it is not necessary to use all allocated RACHs in consideration of the boundary of a large cell. The selector 1204 may select this length in consideration of path loss and round trip delay based on the distance between the UE and the base station.

The intra-cell location information (PC) of the UE used when the length selector 1204 is used to select the length to be used may be already stored in the memory 1203, and may be synchronized with the base station, such as when the UE is newly powered on. In some cases, such as when there is no information on the information, the position information in the cell obtained by performing the initiation access using the allocated total RACH length may be used. To this end, a UE according to an embodiment of the present invention determines a location of a UE in a cell by using a receiver 1201 for receiving a signal in response to an initiation connection from a base station, and synchronization information obtained from the receiver 1201. And a memory 1203 for storing the information PC determined by the in-cell position determining unit 1202.

As described above, the length information L selected by the length selection unit 1204 is input to the sequence application position determination unit 1205 and the sequence application unit 1206, and the sequence application position determination unit 1205 determines this length. The branch determines which part of the total RACH to insert. The determination of the sequence application position determiner 1205 is generally performed arbitrarily by the UE, but may be performed as determined by the control of the base station as described above. Thereafter, the sequence application unit receiving the sequence application position information PS and the sequence application length information L determined as described above forms a channel signal S by applying a sequence having the length L to the assigned RACH to the PS position. do.

FIG. 13 is a block diagram illustrating a characteristic configuration of a base station for receiving an RACH signal from a UE and allocating resources based on a location of the UE in a cell according to an embodiment of the present invention.

In a communication system that increases the length of an RACH that is allowed in proportion to the cell radius, the base station may perform uplink resource allocation based on the intra-cell location determination 1302 and the location information for determining the intra-cell location of each UE. A resource allocator 1303 therefor. Specifically, the above-described position determiner 1302 determines whether the UE is located at a distance from the base station based on the synchronization information received from the start access signal received by the receiver 1301 from any UE. In addition, the determined location information is transmitted to the uplink resource allocation unit 1303. Thereafter, the uplink resource allocator 1303 performs uplink resource allocation of the UE based on the location information acquired by the location determiner 1302. In this case, the allocation of the uplink resource allocator 1303 to each UE may be the length to be used by applying the actual sequence among the RACHs for each UE and to which part of the RACH to transmit the sequence having the length.

On the other hand, the signal transmission method according to another embodiment of the present invention as to how to increase the transmission success rate if the retransmission is performed in case there is no response from the base station for the random access over the RACH as described in detail below Shall be.

14 is a diagram for describing a method of forming an RACH signal when a RACH signal is retransmitted because there is no response from a base station for a random access of a UE according to an embodiment of the present invention.

In case of accessing the RACH by dividing the RACH, there is a method of increasing the transmission power when the base station does not recognize the signal in the first attempt. However, a method of additionally adjusting the length of the RACH may be used. That is, if the power used at the first transmission point is P1 and the length is L1, the power to be used at the second transmission point is P2 (P1≤P2) and the RACH length is L2 (L1≤L2). By adjusting the amount of power and the length of the RACH signal to be transmitted, a method for increasing the probability of correctly receiving at the base station at the time of retransmission can be devised. In addition, in the OFDM system, since the effect of increasing the transmission power during retransmission is not great, the RACH length may be increased while maintaining the transmission power. In addition, as shown in the embodiment illustrated in FIG. 14, when increasing the length of a sequence transmitted at each transmission time point, the length of a sequence transmitted may be transmitted with an increased form along the time axis in the time frequency domain of OFDM. It may be transmitted separately in the form of increased frequency axis. Accordingly, the effect of increasing the diversity in the time and / or frequency domain can be obtained.

In the case of FIG. 14, the UE divides the RACH into three slots, and the example shown uses only 1/3 for the first approach, 2/3 for the next time, and 3rd for the whole. It is an example. That is, a part of the allocated RACH is filled with a signal and transmitted, but a signal having a different length is transmitted in every retransmission. In this case, the type of signal to be used may be extended to the format shown in FIG. 7.

Referring to the retransmission method according to an embodiment of the present invention as described above in more detail, as follows.

15 is a flowchart illustrating a method of forming an RACH signal when a RACH signal is retransmitted because there is no response from a base station for a random access of a UE according to an embodiment of the present invention.

In step S1501, any UE performs random access to the base station. In this case, the length of the sequence that the UE uses for the RACH does not use the entire length of the RACH allocated to all UEs in the cell, but has a length specific for each UE selected according to how far each UE is located from the base station. The connection is made using the RACH signal. When receiving a response from the base station for this random access, the UE proceeds to step S1502 to achieve the intended purpose via the RACH.

On the other hand, if there is no response from the base station for the random access of step S1501, the flow advances to step S1503 to perform backoff by an arbitrary length. Thereafter, in step S1504, the UE increases the transmission power compared to the previously transmitted RACH signal. In addition, an appropriate RACH connection length is selected through step S1505. In FIG. 15, the case in which both the transmission power and the length of the sequence to be used are increased by using the steps S1504 and S1505 as described above, is described. It will be appreciated by those skilled in the art that it is also possible to increase only the length of the signal. Thereafter, the UE returns to step S1501 to perform random access again and repeat the above-described process.

The detailed description of the preferred embodiments of the invention disclosed as described above is provided to enable any person skilled in the art to make and practice the invention. Although the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can. For example, although the present invention has been described with reference to the channel structure based on the RACH, in the system of increasing the channel length according to the increase in the cell radius, as long as the signal length applied according to the distance between the UE and the base station can be selected, This approach can be applied to any channel. In addition, in the above-described embodiments, when the cell radius is increased, not only when the length of the entire channel is increased but also when only the preamble of the channel, specifically, the RACH, is increased, the UE can be used based on the location information of the UE. It is also possible to select the length of the preamble to transmit the channel signal.

Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

According to one embodiment of the present invention as described above, in case of "Nearby UEs" that are close to the base station even in a large cell, by using only a part of the total RACH length, each UE can randomly access the base station (random access opportunity) ) Can be increased, and also, since random slots to which each UE can be randomly increased increase the probability of collision of random accesses of respective UEs as a whole.

In addition, according to the random access failure to the base station may also have the effect of increasing the random access success probability by increasing the length of the sequence to be applied within the RACH length allowed when retransmitting the RACH signal.

In addition, by efficiently allocating the increased RACH slot to the plurality of UEs as described above, it is possible to more efficiently receive the RACH signal of the plurality of UEs.

Claims (20)

In the signal transmission method of the user equipment in the communication system, Selecting a length to be used for connection with a base station among total channel lengths based on the location information in the cell of the user equipment; And Transmitting a channel signal having the selected length. The method of claim 1, And the communication system increases the overall channel length in proportion to a cell radius. The method according to claim 1 or 2, The channel is a random access channel, The location information in the cell of the user device, An initial access step of accessing the base station using the entire length of the random access channel; And And determining a location in the cell of the user equipment via a signal received from the base station in response to the initiating connection. The method of claim 3, wherein And storing the determined in-cell location information. The method of claim 3, wherein And the location determining step determines the location in the cell of the user equipment by comparing the information received from the base station in response to the initiating connection and the information transmitted in the initiating connection to the base station. The method of claim 3, wherein And the initiating connection step is performed when the user equipment is powered on. The method according to claim 1 or 2, Wherein the length selection step selects a length to be used for the connection in consideration of a path loss and a round trip delay based on the position information. The method according to claim 1 or 2, And determining a position at which signals having the length selected in the length selecting step are to be inserted in the entire channel. The method according to claim 1 or 2, And if there is no response from the base station for transmission in the transmitting step, transmitting by increasing the selected length. The method according to claim 1 or 2, And when there is no response from the base station to the transmission in the transmitting step, transmitting by increasing the transmission power of the transmitting channel. The method according to claim 1 or 2, And if there is no response from the base station for transmission in the transmission step, transmitting by increasing the selected length and transmission power of the transmitting channel. In the signal transmission method of the user equipment in the communication system, Increasing a spreading coefficient of a sequence inserted into a channel in proportion to a distance between the user equipment in the cell and the base station; And Applying the spread sequence to the channel and transmitting. In the signal transmission method of the user equipment in the communication system, Increasing the number of repetitions of the sequence inserted into the channel in proportion to the distance between the user equipment in the cell and the base station; And Applying the repeated sequence to the channel and transmitting. In the resource allocation method of the base station in the communication system, Determining a channel length to be used by the user device among the total channel lengths based on the location information in a cell of a predetermined user device; And Allocating a position of a portion of the entire channels having a channel length for use by the user equipment. The method of claim 14, The channel includes an uplink shared channel, The location information in the cell of the user equipment is obtained through an initiating access using a random access channel of the user equipment. In the communication system receiving signal of the base station, Determining channel lengths to be used by the plurality of user devices, respectively, based on the in-cell location information of a plurality of user devices in a cell; Allocating positions of portions of the entire channels each having a channel length for use by the plurality of user devices; And Receiving signals from the plurality of user devices from the assigned location. In the random access channel structure to the communication system to increase the length of the random access channel allowed in proportion to the cell radius, And a random access channel signal having a length selected based on the location information in the cell of the user equipment in a predetermined position among all of the allowed random access channels. In the channel former of the user equipment in the communication system, A length selection unit for selecting a length to be used for connection with a base station among all channel lengths based on the location information in the cell of the user equipment; A position determiner configured to determine a position at which the channel signal having the length selected by the length selector is inserted in the entire channel; And And a sequence application unit for applying a sequence to a channel based on the selected length and the position information to be inserted. The method of claim 18, The channel is a random access channel, The channel former, A receiver for receiving a signal received from the base station in response to an initiating access to the base station using the entire length of the random access channel; An in-cell position determination unit for determining a position in the cell of the user equipment through the signal received by the receiver; And And a memory for storing the determined in-cell location information. A base station in a communication system for increasing the length of an allowed channel in proportion to a cell radius, A position determination unit receiving an initiation access signal through a random access channel of the user equipment in the cell and acquiring position information in the cell of the user equipment; And And a resource allocator for allocating uplink shared channel resources of the user equipment based on the location information obtained by the location determiner.

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