KR20070102791A - Apparatus and method for transmitting broadcasting message in mobile communication systems - Google Patents

Abstract

A method and an apparatus for transmitting a broadcasting message in a mobile communication system are provided to enlarge a cell area of a base station by inserting a broadcasting message with a high MCS level between broadcasting messages with low MCS levels. An apparatus for transmitting a broadcasting message in a mobile communication system includes an MCS(Modulation and Coding Scheme) level determining unit(307), a coder(301), and a modulator(303). The MCS level determining unit determines an MCS level according to a transmission interval of the broadcasting message. The coder codes the broadcasting message according to a determined coding rate. The modulator modulates the broadcasting message according to the determined modulation scheme. The MCS level determining unit determines the MCS level as a first MCS level, when the transmission interval of the broadcasting message corresponds to a first interval. The MCS level determining unit determines the MCS level as a second MCS level, when the transmission interval of the broadcasting message corresponds to a second interval.

Description

Apparatus and method for transmitting broadcast message in wireless communication system {APPARATUS AND METHOD FOR TRANSMITTING BROADCASTING MESSAGE IN MOBILE COMMUNICATION SYSTEMS}

1 is a diagram illustrating a frame structure of a typical OFDM system;

2 is a diagram illustrating a structure for transmitting a frame including a broadcast message having different MCS levels according to an embodiment of the present invention;

3 is a block diagram of an apparatus for switching and transmitting an MCS level of a broadcast message according to the present invention;

4 is a diagram illustrating a procedure for transmitting a broadcast message in a wireless communication system according to an embodiment of the present invention;

5 is a diagram illustrating a procedure for transmitting a signal according to an MCS level section in a wireless communication system according to an embodiment of the present invention; and

6 is a diagram illustrating a signal flow according to an MCS level section in a wireless communication system according to an exemplary embodiment of the present invention.

The present invention relates to an apparatus and a method for transmitting a broadcasting message in a wireless communication system, and more particularly, to a modulation and coding scheme according to a channel distribution characteristic of the broadcasting message in the wireless communication system. The present invention relates to an apparatus and a method for switching and transmitting a level. Here, the channel distribution characteristic is meant to include CQI (Channel Quality Information) information, the distribution of the terminal and the policy of the service provider.

In the wireless communication system, the terminal receives a control message from the base station, acquires channel information and synchronization, and attempts to access the base station. Therefore, the base station broadcasts a control message including channel information and synchronization information so that all terminals included in cell coverage can access the base station. In the following description, the broadcast control message will be referred to as a broadcast message. For example, in a wireless communication system using Orthogonal Frequency Division Multiplexing (hereinafter, referred to as OFDM), the terminal uses a preamble signal received from the base station, and then physically synchronizes a MAP message. Acquire channel information by using. Accordingly, the base station sets and broadcasts a low MCS level so that all terminals included in the cell area can receive the MAP message.

The MCS level of the broadcast message is set to an optimized value of each base station in consideration of the distance between the base stations and the cell area. For example, the MCS level may be determined by using a carrier to interference and noise ratio (hereinafter referred to as CINR) of a channel between the base station and the terminal as shown in Table 1 below. have.

MCS Level CINR 1 (QPSK 1/12) -1 dB <CINR ≤ 4 dB 2 (QPSK 1/8)  4 dB <CINR ≤ 9 dB 3 (QPSK 1/4) 9 dB <CINR ≤ 13 dB 4 (QPSK 1/2) 13 dB <CINR ≤ 20 dB 5 (QPSK 3/4) 20 dB <CINR ≤ 22 dB . . . . . .

As shown in Table 1, when the CINR value of a specific UE is greater than -1 dB and less than or equal to 4 dB, the modulation scheme uses quadrature phase shift keying (QPSK) and a coding rate of 1/12.

If, in Table 1, it is assumed that the modulation scheme with the MCS level of the broadcast message of 4 is QPSK and the coding rate is 1/2, the channel environment among the terminals included in the cell region of the base station ( Only terminals with a CINR) of 13 dB or more may receive the broadcast message. That is, when the broadcast message is transmitted using a high MCS level, terminals having a bad channel environment (CINR) located outside the cell area cannot receive the broadcast message.

Accordingly, the base station transmits a broadcast message having a low MCS level in order to transmit the same broadcast message to terminals having a poor channel environment located outside the cell area. That is, the lower the MCS level, the wider the cell area in which the base station can transmit a broadcast message. However, when a low MCS level is used, as shown in FIG. 1, since many channel resources are required to transmit a broadcast message in one frame, channel resources for allocating traffic are reduced.

1 shows a frame structure of a typical OFDM system. The following description shows only the downlink frame of the OFDM system.

Referring to FIG. 1, FIG. 1A shows a downlink frame using a coding rate of 1/2 for a modulation scheme of QPSK having an MCS level of 4 in Table 1, and FIG. 1B shows a table in FIG. A downlink frame using a coding rate of 1/12 is used for a QPSK modulation scheme having an MCS level of 1. That is, it is assumed that FIG. 1A uses a high MCS level and FIG. 1B uses a low MCS level.

As shown, when the broadcast message is transmitted using the low MCS level of FIG. 1A, more channel resources are required than the broadcast message transmission using the high MCS level of FIG. 1B. Accordingly, FIG. 1A reduces channel resources for transmitting traffic than FIG. 1B, thereby lowering operational efficiency of channel resources.

As described above, when transmitting a broadcast message of a low MCS level in order to widen a cell area in a wireless communication system, a lot of channel resources are consumed to transmit the broadcast message, thereby reducing channel resources for transmitting traffic. That is, there is a problem in that the traffic throughput decreases. In addition, when transmitting a broadcast message of a high MCS level to increase the transmission rate, there is a problem that the cell area of the base station is narrowed.

Accordingly, an object of the present invention is to provide an apparatus and method for expanding a cell area by adjusting an MCS level of a broadcast message in a wireless communication system.

Another object of the present invention is to provide an apparatus and method for increasing cell rate by adjusting MCS level of a broadcast message in a wireless communication system.

Another object of the present invention is to provide an apparatus and method for expanding a cell area by inserting and transmitting a low MCS level broadcast message in a base station transmitting a high MCS level broadcast message in a wireless communication system.

Another object of the present invention is to provide an apparatus and method for increasing a cell rate by inserting and transmitting a high MCS level broadcast message in a base station transmitting a low MCS level broadcast message in a wireless communication system.

According to a first aspect of the present invention for achieving the above object, a method of transmitting a broadcast message in a wireless communication system, the method of the first modulation and coding scheme (Modulation and Coding Scheme) level during the first period for transmitting the broadcast message And transmitting a broadcast message of a second modulation and coding scheme level during a second period of transmitting the broadcast message.

According to a second aspect of the present invention, a method of transmitting a broadcast message in a wireless communication system includes: checking a modulation and coding scheme level of a section for transmitting the broadcast message; And encoding and modulating the broadcast message according to a technique level, and transmitting the encoded and modulated broadcast message.

According to a third aspect of the present invention, a method for transmitting a signal according to a modulation and coding scheme level section in a wireless communication system includes, when an uplink signal is received, the modulation and code in which the signal is received. Identifying a technique level interval and, if the signal is received in a first interval having a modulation and encoding scheme level lower than another modulation and encoding scheme level interval, transmitting a response signal during the received first interval; And transmitting the response signal to the next section having the same modulation and coding scheme level as the first section if the response signal cannot be transmitted during the first section. .

According to a fourth aspect of the present invention, a transmission apparatus of a wireless communication system includes a modulation and coding scheme level determiner for determining a modulation and coding scheme level of the broadcast message according to a section for transmitting a broadcast message, and the determined code rate ( And an encoder for encoding the broadcast message according to a coding rate, and a modulator for modulating the broadcast message according to the determined modulation scheme.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, detailed descriptions of related known functions or configurations will be omitted if it is determined that the detailed description may unnecessarily obscure the subject matter of the present invention.

Hereinafter, a description will be given of a technique for adjusting a modulation and coding scheme (hereinafter, referred to as MCS) level of a broadcasting message in a wireless communication system. In other words, a base station transmitting a high MCS level broadcast message in the wireless communication system inserts and transmits a low MCS level broadcast message, thereby extending a cell area, and a high MCS level at a base station transmitting a low MCS level broadcast message. A technique for increasing cell rate by inserting and transmitting a broadcast message is described. Here, the low MCS level and the high MCS level of the broadcast message are determined by comparing the MCS levels used for the broadcast message transmission. The broadcast message may include a MAP message, a MAC (Media Access Control) message, an Uplink Channel Description (UCD) message, a Downlink Channel Description (DCD) message, and the like.

2 is a diagram illustrating a structure of inserting a frame transmitted in a broadcast message having a different MCS level according to an embodiment of the present invention.

As shown in FIG. 2, this indicates an MCS level of a broadcast message included in each frame transmitted from a base station to terminals included in a cell area. The base station transmits frames including the broadcast message according to a predetermined MCS level according to a distance from neighboring base stations and a cell area. In this case, frames (D1 frame section 203 and D2 frame section 205) including broadcast messages having different MCS levels are inserted and transmitted for cell area extension or cell throughput increase. Here, the frame period including the broadcast message of the other MCS level, the transmission period (L1 frame interval 201) of the frame including the MAP message of the MCS level and the other MCS level is received from the terminals at the base station. It is determined using channel distribution characteristics such as received CQI (Channel Quality Information) information, the distribution of the UE included in the cell area of the base station, the policy of the service provider.

For example, referring to <Table 1>, if the base station transmits a broadcast message using a modulation scheme of QPSK having an MCS level of 4 and a high MCS level with a coding rate of 1/2, carrier band interference And only a terminal in a channel environment having a carrier to interference and noise ratio (hereinafter referred to as CINR) of 13 dB or more may receive the broadcast message and access the base station. At this time, a broadcast message using a modulation scheme of QPSK having a MCS level of 2 and a coding rate of 1/8 is transmitted during the D1 frame section 203 at a predetermined period (L1 frame interval 201). In this case, since the UEs in the channel environment having a CINR of 4 dB or more can receive and access the broadcast message of the base station without significantly reducing the data rate, the cell area can be extended.

In addition, when the base station transmits a broadcast message using a modulation scheme of QPSK having a MCS level of 1 and a low MCS level with a coding rate of 1/12, a terminal in a channel environment having a CINR of -1 dB or more receives the broadcast message. Can be connected to the base station. At this time, a broadcast message using a modulation scheme of QPSK having a MCS level of 4 and a coding rate of 1/2 is transmitted during the D1 frame section 203 at a predetermined period (L1 frame interval 201). In this case, only UEs in a channel environment having a CINR of 13 dB or more can access the base station, thereby increasing the cell rate.

As described above, the base station transmits the broadcast message according to the MCS level interval set using a channel environment, a distribution of terminals, and a service provider's policy.

3 is a block diagram of an apparatus for switching and transmitting an MCS level of a broadcast message according to the present invention.

As shown in FIG. 3, a base station for transmitting a broadcast message having a different MCS level includes an encoder 301, a modulator 303, a signal transmitter 305, an MCS level determiner 307, and a reception signal discriminator 309. And a transmission controller 311.

The encoder 301 performs channel coding on transmission signals (eg, traffic and response signals) according to a corresponding code rate. In addition, according to the present invention, the broadcast message is channel-coded according to the code rate provided from the MCS level determiner 307. The modulator 303 modulates and outputs data provided from the encoder 301 according to a corresponding modulation scheme. At this time, the broadcast message is modulated and output by the modulation scheme provided from the MCS level determiner 307.

As illustrated in FIG. 2, the MCS level determiner 307 determines the MCS level of the broadcast message transmitted according to a predetermined MCS level interval and transmits the MCS level to the encoder 301 and the modulator 303. Here, the MCS level and the interval are determined using CQI (Channel Quality Information) information received from the terminals, the distribution of the terminal included in the cell area of the base station, the policy of the service provider.

The signal transmitter 305 converts the baseband signal provided from the modulator 303 into a radio frequency (RF) signal and transmits the signal to the terminal through an antenna. In this case, when the signal transmitter 305 transmits the response signal of the uplink signal received from the terminal, the response signal is transmitted under the control of the transmission controller 311. For example, when the transmission permission signal is received from the transmission controller 311, the signal transmitter 305 transmits the response signal to the terminal through an antenna. If a non-transmission signal is received from the transmission controller 311, the signal transmitter 305 stores the response signal in the buffer 321. Thereafter, when a transmission signal is received from the transmission controller 311, the response signal stored in the buffer 321 is transmitted to the terminal through an antenna.

The transmission controller 311 determines whether or not a response signal is transmitted in consideration of the reception time of the signal provided from the reception signal discriminator 309 and the remaining time and resources of the MCS level section in which the signal is received. Control transmitter 305. For example, when transmitting a response signal for a ranging signal received in a low MCS level section, it is determined whether the response signal can be transmitted by checking the remaining time and resources of the received low MCS level section. . If the response signal can be transmitted, a transmission permission signal is generated to transmit the response signal to the signal transmitter 305. On the other hand, if the response signal cannot be transmitted, the signal transmitter 305 stores the response signal in the buffer 321 to generate a transmission impossible signal to transmit the next low MCS level interval. Here, the response signal to the signal received in the high MCS level section can be transmitted regardless of the MCS level section.

The reception signal discriminator 309 checks a reception time of an uplink signal (for example, a ranging request signal) received from the terminal and transmits the received time to the transmission controller 311.

4 illustrates a procedure for transmitting a broadcast message in a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 4, first, the base station determines whether a broadcast message is transmitted in step 401. If the broadcast message is transmitted, the base station determines the MCS level for transmitting the broadcast message by checking a predetermined MCS level section in step 403. Here, the MCS level section and the MCS level are determined using CQI (Channel Quality Information) information received from the terminals, the distribution of the terminals included in the cell area of the base station, the policy of the service provider, and the like.

In step 405, the base station encodes and modulates the broadcast message according to the identified MCS level.

After encoding and modulating the broadcast message according to the set MCS level interval, the base station proceeds to step 407 and transmits the broadcast message. The base station then terminates this algorithm.

Hereinafter, as shown in FIG. 2, when the broadcast message is transmitted by the base station according to the control period and interval of the set MCS level, a procedure of transmitting and receiving a signal between the base station and the terminal will be described.

5 illustrates a procedure for transmitting a signal according to an MCS level section in a wireless communication system according to an embodiment of the present invention. In the following description, ranging between the terminal and the base station is described by way of example.

Referring to FIG. 5, first, the base station determines whether an uplink signal, that is, a ranging request signal, is received from the terminal in step 501. If the ranging request signal is received, the base station proceeds to step 503 and checks the MCS level of the section in which the ranging request signal is received.

If the interval in which the ranging request signal is received is a low MCS level interval, the base station proceeds to step 505 in which a response signal not transmitted during the previous low MCS level interval is transmitted to the buffer 321 of the signal transmitter 305. Check if it exists. If there is no response signal that has not been transmitted to the buffer 321, the base station determines whether it can transmit a response signal to the received ranging request signal in step 509.

On the other hand, if there is a response signal that can not be transmitted to the buffer 321, the base station proceeds to step 507 and transmits the previous response signal stored in the buffer 321.

In step 509, the base station determines whether the ranging request signal can transmit a response signal for the ranging request signal during the low MCS level period in which the ranging request signal is received. Here, whether or not the response signal can be transmitted is determined by checking remaining time and resources of the low MCS level section.

If the response signal can be transmitted, the base station proceeds to step 511 and transmits the response signal, and then the base station ends the present algorithm.

On the other hand, if the response signal cannot be transmitted, the base station proceeds to step 513 and stores the response signal in the buffer 321, the base station terminates the algorithm.

In step 503, if the section in which the ranging request signal is received is a high MCS level section, the base station proceeds to step 515 and transmits a response signal to the ranging request signal.

In step 517, the base station determines whether the same ranging signal as the received ranging request signal exists among the ranging request signals received during the low MCS level period. Here, since the ranging request signal and the response signal having the high MCS level can be transmitted and received even during the low MCS level period, the ranging request signal of the high MCS level may be received during the low MCS level period. At this time, when transmitting a response signal for the ranging request signal of the high MCS level received in the low MCS level interval, it is determined whether the response signal can be transmitted. If transmission of the response signal is impossible, the response signal is stored in the buffer 321 for transmission in the next low MCS level section.

If the same signal as the received ranging request signal exists, the base station determines whether a response signal to the ranging request signal exists in the buffer 321 in step 519.

If there is a response signal to the ranging request signal in the buffer 321, the base station proceeds to step 521 and deletes the response signal from the buffer 321. The base station then terminates this algorithm.

As described above, the base station does not transmit a response signal according to the MCS level of the received uplink signal, but transmits the response signal according to the MCS level section when the uplink signal is received.

Hereinafter, an exemplary embodiment of transmitting and receiving a signal according to an MCS level section set as shown in FIG. 5 will be described.

6 illustrates a signal flow according to an MCS level section in a wireless communication system according to an exemplary embodiment of the present invention. In the following description, ranging between the terminal and the base station is described by way of example.

Referring to FIG. 6, FIG. 6A assumes that a frame having a low MCS level broadcast message is inserted in the middle of a frame transmitting a high MCS level broadcast message, and FIG. 6B shows a broadcast message having a low MCS level broadcast message. It is assumed that a frame having a high MCS level broadcast message is inserted in the middle of the frame.

First, as illustrated in FIG. 6A, the base station inserts and transmits a frame of a low MCS level broadcast message during an intermediate D1 frame section 601 that transmits a frame of a high MCS level broadcast message. As described above, while the MCS level section is set, the terminal transmits a ranging request signal 611 of a high MCS level to the base station during the high MCS level section.

The base station receiving the ranging request signal 611 in the high MCS level section transmits a response signal 613 to the ranging request signal. In this case, the high MCS level signal may be transmitted during the low MCS level period.

Thereafter, the terminal transmits a ranging request signal 615 having a low MCS level in a low MCS level section. The base station receiving the ranging request signal determines whether it is possible to transmit a response signal to the ranging request signal during the low MCS level section (D1 frame section 601). If the response signal can be transmitted, the base station transmits the response signal. On the other hand, if transmission of the response signal is impossible, the base station stores the response signal in the buffer 321, and then transmits the response signal 617 in the next lower MCS level section (D2 frame section 603). do.

Next, as illustrated in FIG. 6B, the base station inserts and transmits a frame of a high MCS level broadcast message during an intermediate D1 frame section 621 which transmits a frame of a low MCS level broadcast message. As described above, while the MCS level section is set, the terminal transmits a ranging request signal 631 having a low MCS level to the base station during the low MCS level section.

The base station receiving the low MCS level ranging request signal 631 determines whether a response signal for the ranging request signal can be transmitted during the current low MCS level interval. If the response signal can be transmitted, the base station transmits the response signal. On the other hand, if transmission of the response signal is impossible, the base station stores the response signal in the buffer 321 and then transmits the response signal 635 in the next low MCS level interval.

Thereafter, the terminal transmits a ranging request signal 633 having a high MCS level to the base station in a high MCS level section (D1 frame section 621). The base station transmits a response signal 637 to the ranging request signal in the high MCS level period. In this case, the high MCS level signal may be transmitted during the low MCS level period.

After transmitting and receiving a signal according to the set MCS level as described above, the base station transmits the broadcast message to the terminal according to the set MCS level interval.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, since the MCS level of the broadcast message is switched and transmitted according to the channel environment in the wireless communication system, that is, a low MCS level broadcast message is inserted in the middle of transmitting a high MCS level broadcast message. The cell area of the base station can be expanded, and the cell rate of the base station can be increased by inserting a high MCS level broadcast message in the middle of transmitting the low MCS level broadcast message.

Claims (28)

In the broadcast message transmission method in a wireless communication system, Transmitting the broadcast message of a first modulation and coding scheme level during a first period of transmitting the broadcast message; Transmitting a broadcast message of a second modulation and coding scheme level during a second period of transmitting the broadcast message. The method of claim 1, Wherein the first modulation and coding scheme level is determined using at least one of a distance between base stations and a size of a cell area of the base station. The method of claim 1, The second modulation and coding scheme level is determined using at least one of channel quality information and distribution of the terminal. The method of claim 1, The size of the second interval is determined using at least one of channel quality information and distribution of the terminal. The method of claim 1, The first section and the second section, characterized in that repeated in a predetermined period. The method of claim 5, The predetermined period is determined using at least one of channel quality information and distribution of the terminal. In the broadcast message transmission method in a wireless communication system, Checking a modulation and coding scheme level of a section for transmitting the broadcast message; Encoding and modulating the broadcast message according to the identified modulation and coding scheme level; Transmitting the encoded and modulated broadcast message. The method of claim 7, wherein The interval for transmitting the broadcast message, And a first section for setting a modulation and coding scheme level of the broadcast message as a first modulation and coding scheme level, and a second section for setting a second modulation and coding scheme level. How to. The method of claim 8, Wherein the first modulation and coding scheme level is determined using at least one of a distance between base stations and a size of a cell area of the base station. The method of claim 8, The second modulation and coding scheme level is determined using at least one of channel quality information and distribution of the terminal. The method of claim 8, The size of the second interval is determined using at least one of channel quality information and distribution of the terminal. The method of claim 8, The first section and the second section, characterized in that repeated in a predetermined period. The method of claim 12, The predetermined period is determined using at least one of channel quality information and distribution of the terminal. A method for transmitting a signal according to a modulation and coding scheme level in a wireless communication system, When the uplink signal is received, checking a modulation and coding scheme level section in which the signal is received; When the signal is received in a first section having a modulation and coding scheme level lower than another modulation and coding scheme level section, checking whether the signal can transmit a response signal during the received first section; If the response signal cannot be transmitted during the first interval, transmitting the response signal to a next interval having the same modulation and coding scheme level as the first interval. The method of claim 14, The modulation and coding scheme level interval, And a first section for setting a modulation and coding scheme level of the broadcast message to a first modulation and coding scheme level, and a second section for setting a second modulation and coding scheme level. The method of claim 15, Wherein the first modulation and coding scheme level is determined using at least one of a distance between base stations and a size of a cell area of the base station. The method of claim 15, The second modulation and coding scheme level is determined using at least one of channel quality information and distribution of the terminal. The method of claim 15, The size of the second interval is determined using at least one of channel quality information and distribution of the terminal. The method of claim 15, The first section and the second section, characterized in that repeated in a predetermined period. The method of claim 19, The predetermined period is determined using at least one of channel quality information and distribution of the terminal. The method of claim 14, When the signal is received in the first section, checking whether there is a response signal that has not been transmitted in the previous section having the same modulation and coding scheme level as the first section; And transmitting the response signal when the response signal exists. In the transmitting device of a wireless communication system, A modulation and coding scheme level determiner for determining a modulation and coding scheme level of the broadcast message according to a section for transmitting the broadcasting message; An encoder for encoding the broadcast message according to the determined coding rate; And a modulator for modulating the broadcast message according to the determined modulation scheme. The method of claim 22, The modulation and coding scheme level determiner, If the interval for transmitting the broadcast message is a first interval, the modulation and coding scheme level of the broadcast message is determined as the first modulation and coding scheme level, And when the interval for transmitting the broadcast message is a second interval, determining a modulation and coding scheme level of the broadcast message as the second modulation and coding scheme level. The method of claim 23, wherein Wherein the first modulation and coding scheme level is determined using at least one of a distance between base stations and a size of a cell area of the base station. The method of claim 23, wherein The second modulation and coding scheme level is determined using at least one of channel quality information and distribution of the terminal. The method of claim 22, A reception signal discriminator for identifying a modulation and coding scheme level section in which the signal is received, when an uplink signal is received; A transmission controller controlling transmission of a response signal to the uplink signal according to a modulation and coding scheme level interval in which the uplink signal is received; And a signal transmitter for transmitting the encoded and modulated broadcast message and transmitting the response signal under the control of the transmission controller. The method of claim 26, The transmission controller, If the uplink signal is received in a first section having a modulation and coding scheme level lower than another modulation and coding scheme level interval, it is determined whether a response signal can be transmitted during the first interval in which the signal is received. And if the response signal cannot be transmitted, generating a control signal to transmit the response signal to a next section having the same modulation and coding scheme level as the first section. The method of claim 27, The signal transmitter, Including a memory for storing the response signal, And when the control signal is received from the transmission controller to transmit the response signal in a next section, the response signal is stored in the memory.

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