KR20060031193A - Method and apparatus for transmitting channel quality indicator of forward auxiliary pilot channel in mobile telecommunication systems - Google Patents

Abstract

The present invention provides a mobile communication system including a base station having a beamforming antenna and a mobile terminal provided with a high speed data service through the beamforming antenna, wherein the mobile station transmits a channel quality index of a forward auxiliary pilot channel to the base station. In the transmitting method, the process of demodulating the forward secondary pilot channel of the serving and non-serving beams to measure the channel quality index, and using the measured channel quality index to find a beam having the channel quality index of the best forward secondary pilot channel And if the beam having the best channel quality and the serving beam are the same, encoding a reception quality measurement result of the forward auxiliary forward pilot channel and modulating the encoded channel reception quality index into a reverse channel. Characterized in the transmission box.

Packet data channel, auxiliary pilot channel, beamforming, multibeam, sector, beam, system capacity.

Description

{Method and Apparatus for transmitting channel quality indicator of forward auxiliary pilot channel in mobile telecommunication systems}             

1 illustrates a three sector structure of a base station in a general mobile communication system.

2 is a diagram illustrating beamforming of a base station in which a smart antenna is installed in a general mobile communication system;

3 is a diagram illustrating a three-sector structure beamed using a typical cell engraving system;

 4A is a diagram illustrating beam coverage for transmitting a forward auxiliary pilot channel and a forward auxiliary pilot channel when the forward packet data control channel is not beamformed;

4B is a diagram illustrating beam coverage for transmitting a forward packet data channel, a forward auxiliary pilot channel, and a forward packet data control channel when the forward packet data control channel is included in beamforming;

5 is a diagram illustrating the structure of a forward packet data channel (F-PDCH) specified in the 1xEV-DV standard;                 

FIG. 6 is a diagram illustrating a structure of a forward packet data control channel (F-PDCCH) defined in the 1xEV-DV standard. FIG.

7 illustrates a structure of a general forward auxiliary pilot channel (F-APICH),

8 illustrates a structure of a base station transmitter for transmitting a forward packet data channel and a forward auxiliary pilot channel through an array antenna when the forward packet data control channel is not beamformed based on a general smart antenna structure;

9 illustrates a structure of a base station transmitter for transmitting a forward packet data channel, a forward auxiliary pilot channel, and a forward packet data control channel through an array antenna when the forward packet data control channel based on a general smart antenna structure is included in beamforming. Drawing,

FIG. 10 is a diagram illustrating a structure of a reverse channel quality index channel (R-CQICH) defined in a 1xEV-DV standard. FIG.

11 illustrates a structure of a reverse channel quality index channel (R-CQICH) according to an embodiment of the present invention;

12A illustrates a beam when all base stations around a mobile terminal do not beamform a forward packet data channel according to an embodiment of the present invention;

12B is a diagram illustrating a beam when all base stations around a mobile terminal beamform a forward packet data channel according to an embodiment of the present invention;

12C is a diagram illustrating a beam when some base stations around a mobile terminal beamform a forward packet data channel according to an embodiment of the present invention;                 

13 is a diagram illustrating an apparatus of a mobile terminal for transmitting a channel quality index of a forward auxiliary pilot channel according to an embodiment of the present invention;

14 is a diagram illustrating a process of encoding a channel quality index of a forward secondary pilot channel (F-APICH) and transmitting it to a base station through a reverse channel quality index channel (R-CQICH) according to an embodiment of the present invention;

15 is a diagram illustrating a process of encoding a reception quality index of a forward secondary pilot channel (F-APICH) into a control message and transmitting the same to a base station through a reverse dedicated control channel (R-DCCH) according to an embodiment of the present invention;

16 is a diagram illustrating a process of encoding a reception quality index of a forward secondary pilot channel (F-APICH) and transmitting it to a base station through a reverse beamforming control channel (R-BFCCH) according to the present invention.

 The present invention relates to a method and apparatus for beamforming in a mobile communication system, and more particularly, to a method and apparatus for applying a reception quality index of a forward auxiliary pilot channel received from a mobile terminal at a base station to forward beamforming.

In general, a mobile communication system divides a frequency band determined according to a communication method into a plurality of channels and uses a frequency division multiplexing scheme (FDMA) that uses a frequency channel allocated to each subscriber, and a plurality of frequency channels. Time Division Multiple Access (TDMA), where subscribers divide time, and code division multiplexing (TDMA), where multiple subscribers use the same frequency band in the same time zone and assign different codes for each subscriber Division Multiple Access, hereinafter referred to as CDMA). Such mobile communication systems are currently reaching a stage of providing a general voice call service and a packet data service capable of transmitting a large amount of digital data according to the rapid development of communication technology.

The mobile communication system for providing the high-speed data service generally adopts the CDMA scheme, and the CDMA scheme is divided into a synchronous scheme adopted in the United States and the asynchronous scheme adopted in Europe and Japan, as is known, for each country. Various studies are in progress.

The mobile communication system currently under study regarding the packet data service includes EV-DO (Evolution Data Only), which enables high-speed packet transmission in a synchronous manner, and EV-DV, which supports simultaneous voice and high-speed packet data service. (Evolution of Data and Voice) and W-CDMA in asynchronous manner.

In the case of the packet data service, the capacity of the forward link from the base station to the mobile terminal is required due to a service characteristic of providing multimedia content to the mobile terminal. One of the solutions for increasing the capacity of the forward link is to increase the data transmission capacity of the base station by sectorizing the antenna of the base station. This replaces the conventional omni omni antenna with 360 degrees of radiation pattern with a directional antenna of 3 sector structure divided by 120 degrees, for example, thereby minimizing interference between mobile terminals located in different sectors. Will be increased.

1 is a diagram illustrating a three sector structure of a base station in a general mobile communication system.

Referring to FIG. 1, a sector structure divides a cell managed by one base station into three sectors S1 to S3, and a plurality of sector antennas are provided for each sector S1 to S3, so that a radio of each sector is provided. It is designed to transmit and receive signals. In general, a base station of a CDMA mobile communication system divides its cell into three sectors (S1 to S3) using different PN code offsets (PN0, PN1, PN2) of the same frequency assignment (FA). . This mode of operation applies equally to voice services and data services.

As shown in FIG. 1, dividing one cell into a plurality of sectors is to reuse the same frequency channel in consideration of distance while eliminating interference between frequency channels. Here, the three sectors S1 to S3 use the same frequency, but since the direction of the base station antenna is directed only to the corresponding sector, the channel interference is reduced to an average of 1/3 so that the base station system can support the mobile terminal located in the cell. Theoretically triples.

However, in a mobile communication system with a relatively low data rate such as IS-95A and IS-95B, a three-sector antenna system can secure sufficient system capacity. However, as the use of high-speed data services such as EV-DO increases, the conventional three-sector antenna It has become difficult to secure channel capacity for smooth operation of base station systems. Therefore, there is a need for a new method for greatly increasing the capacity of a base station system. As a method for this, a smart antenna system that forms a directional beam with a plurality of antenna elements has attracted much attention.

2 illustrates a beam of a base station in which a smart antenna is installed in a general mobile communication system.

The smart antenna system utilizes an adaptive array antenna and advanced high-performance digital signal processing technology to adaptively control the beam pattern of the antenna according to the change of the RF signal environment to maximize the transmission and reception performance and the capacity of the wireless signal. Advanced signal processing and antenna technology.

In the smart antenna system, instead of forming a beam in a forward direction as in the prior art, an optimal directional beam B1 to B4 using a complex weight vector is formed as a mobile terminal of a desired subscriber, as is well known. By forming a pattern null in the directions I1 and I2 of the interference signal, the interference signal is minimized to increase the communication quality and the capacity of the base station system. That is, unlike the conventional base station system in which the total transmission power transmitted from the base station to the mobile terminal of the subscriber is very small, the effective reception power ratio of the mobile terminal is shown in FIG. By optimally combining the received signals at the mobile terminal by the control, the interference signal level is greatly reduced to provide the subscriber with the optimal received signal power.                         

Advantages of the base station system using the smart antenna are high antenna gain, elimination of interference and multipath signals, spatial diversity, good power efficiency and coverage capacity, and high bit rate. (bit rate) and low power consumption.

Types of the smart antenna system include a switched beam antenna, an adaptive array antenna system, and a cell sculpting system that has recently been studied.

However, since the three-sector base station serves an area in which each sector is fixed, frequency resources are inefficiently used when the call volume is biased for each sector area. In addition, the three-sector base station has an excessive cost in managing and maintaining frequency resources.

Among the types of smart antenna system, the cell fragmentation system is a method for overcoming such a problem. The efficiency of the frequency resource is increased by adaptively adjusting the direction of the sector and the beam width of the transmission beam according to the traffic conditions. It is proposed to increase.

3 is a conceptual diagram illustrating a three sector structure beam formed using the cell engraving system.

The cell engraving system forms a plurality of narrow beam width transmission beams using a multi-array antenna, and then calculates the communication amount of each transmission beam so as to reconstruct a sector by synthesizing the beams so that the communication amount is the same for each sector. As a result, the sectors with a large amount of money are narrow and the sectors with a small amount of money are made wide. At this time, the direction and the size of the sector are not adjusted in real time, but after the change of the call volume for a certain period of time.

As described above, the smart antenna system is actively progressing an alternative for increasing the system capacity of the base station. However, the smart antenna system has been developed in the direction of maintaining a three-sector structure up to now, fearing excessive occurrence of handoff when providing a voice service. In other words, dividing a cell of a base station into three or more sectors has the effect of reducing interference between subscribers and increasing subscriber capacity. However, when dividing the cell of the base station into too many sectors, handoff is frequently performed.

Therefore, in case of a voice service sensitive to time delay during handoff, a call drop rate is increased, resulting in a decrease in system efficiency and call quality. Therefore, in the conventional base station system, in which voice service and data service are integrated and operated for each sector, there is a problem in that the sector cannot be divided more for data service due to the above limitation.

Accordingly, an object of the present invention is to provide a channel quality indicator of a forward secondary pilot channel of a mobile terminal when beamforming and transmitting the forward secondary pilot channel to each narrow beam in a high-speed data service using multiple beams. A method and apparatus for transmitting to a base station through reverse control channels are provided.                         

The method for achieving the object of the present invention, a mobile communication system comprising a base station having a beamforming antenna and a mobile terminal provided with a high-speed data service through the beamforming antenna, the mobile terminal is forward-assisted A method of transmitting a channel quality index of a pilot channel to the base station, the method comprising: demodulating the forward secondary pilot channel of the serving and non-serving beams to measure the channel quality index, and using the measured channel quality index of the best forward secondary pilot channel Searching for a beam having a channel quality index, encoding a reception quality measurement result of the forward auxiliary pilot channel when the beam having the best channel quality is the same as the serving beam, and receiving the encoded channel It transmits by modulating the quality index on the reverse channel It shall be.

The apparatus for achieving the object of the present invention includes a base station having a beamforming antenna and a mobile terminal provided with a high speed data service through the beamforming antenna, wherein the mobile terminal is forward-assisted An apparatus for transmitting a channel quality index of a pilot channel to the base station, comprising: a demodulator for demodulating a forward secondary pilot channel of serving and non-serving beams, and a channel quality index measured by measuring the demodulated channel quality index. A channel quality measurement unit for finding a beam having a channel quality index of the best forward auxiliary pilot channel, and a channel quality index encoding the measured channel quality index quality of the forward auxiliary when the beam having the best channel quality is the same as the serving beam A coder and the coded channel quality index into a reverse channel. And a transmitter for transmitting the channel quality index included in the modulated reverse channel.

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, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The present invention will be described in the cdma 2000 Release C (generally referred to as 1xEV-DV) system that can simultaneously support the existing cdma2000 1x service and high-speed forward packet data service in the 1.25 MHz band.

In the 1xEV-DV, the following channels are added in the forward and reverse directions in a range that does not affect the cdma2000 1x service to enable forward high speed packet data transmission.

Firstly, the forward packet data channel (hereinafter referred to as F-PDCH) is a forward channel used by a base station for transmitting packet data, and has six sizes of 408, 792, 1560, 2328, 3096, and 3864 bits. Packet data can be transmitted. The F-PDCH may have three types of frame lengths of 1.25, 2.5, and 5 msec. Accordingly, the data rate of the F-PDCH may range from 81.6 kbps to 3.0912 Mbps. The F-PDCH transmits packet data using one or more Walsh codes in parallel, but the types of Walsh codes that can be used may vary in time. A base station can transmit packet data to multiple users by operating the time division multiplexing (TDM) method of the F-PDCH, and up to two F-PDCHs simultaneously using the code division multiplexing (CDM) method. In this case, two packet data may be transmitted to two different mobile terminals.

Second, a forward packet data control channel (hereinafter referred to as F-PDCCH) is a terminal designation for receiving control information F-PDCH necessary for the mobile terminal to receive packet data transmitted through the F-PDCH. A forward channel used to transmit packet data size, frame length, Walsh code type, etc.) and other control information. Here, the base station may use up to two F-PDCCHs. When it is determined that the F-PDCCH is sent to the mobile station, the mobile station receives the F-PDCH and feeds back a successful reception after a predetermined time.

Third, the reverse channel quality index channel (hereinafter referred to as R-CQICH) is a forward common pilot channel (hereinafter referred to as R-CQICH) received by the mobile station from an base station included in an active set, It is a reverse channel used to measure and compare channel quality of F-CPICH, select a base station to receive forward packet data, and feed back a received channel quality index of the pilot channel to the selected base station. Here, the base station controls the forward power based on a channel quality indicator fed back from each mobile terminal, the size of the base station transmit power that can be used for packet data transmission, and the type of Walsh code that can be used for packet data transmission. , Packet data channel scheduling, packet data channel handoff, and the like.

Fourthly, the reverse acknowledgment channel (hereinafter referred to as R-ACKCH) is a reverse channel used by the mobile station to feed back to the base station whether the F-PDCCH and F-PDCH received from the base station are successfully received.

In addition, the forward auxiliary pilot channel (hereinafter referred to as F-APICH) introduced in the present invention will be described.

In order to provide the 1xEV-DV forward high speed packet data service more efficiently, the F-PDCH can be beamformed and transmitted. There is a problem of phase mismatch occurring when a channel is estimated using a pilot signal. do. Here, the pilot signal is a phase reference for coherent demodulation at the receiver. When the base station broadcasts a forward common pilot channel (hereinafter, referred to as an F-CPICH) through a wide beam of an existing 120 ° sector and transmits an F-PDCH through a beamformed narrow beam, The pilot signal and the data signal arrive at the mobile terminal without passing through the same channel path. Therefore, when the channel is estimated from the pilot signal of the F-CPICH and as a result, the phase mismatch occurs due to different channel paths when demodulating the data signal of the F-PDCH, thereby reducing the efficiency of beamforming.

In order to solve this problem, the 1xEV-DV introduces the F-APICH and uses it for beamforming. Accordingly, since the F-CPICH is still needed for non-beamforming channels, the F-CPICH is transmitted without beamforming, but the F-APICH can be beamformed and transmitted in the same manner as the beamforming of the F-PDCH to solve the phase mismatch problem. That is, if the beam weight is transmitted by multiplying the F-APICH with a complex weight equal to the beamforming complex weight multiplied for beamforming the F-PDCH, the same channel path as the F-PDCH is transmitted. Therefore, the phase mismatch caused by different channel paths is eliminated, and the channel estimation error is greatly reduced. Since the base station allocates different Walsh codes to the F-APICHs that are beamformed and transmitted to the respective narrow beams, the mobile terminal can know which narrow beams it belongs to as the Walsh codes.

Meanwhile, beam coverage for transmitting F-PDCH, F-APICH and F-CPICH when the F-PDCCH is broadcast through a wide beam, and F-PDCH when the F-PDCCH is broadcast through all narrow beams, The beam coverage for transmitting the F-APICH and the F-CPICH will be described with reference to the accompanying drawings. Here, the wide beam refers to a case in which the F-PDCCH is not beamformed, and the narrow beam refers to a case in which the F-PDCCH is included in beamforming.

FIG. 4A illustrates beam coverage for transmitting a forward auxiliary pilot channel and a forward auxiliary pilot channel when beam forwarding is not performed. FIG. 4B illustrates a case in which a forward packet data control channel is included in beamforming. A beam coverage for transmitting a forward packet data channel, a forward auxiliary pilot channel, and a forward packet data control channel of FIG.

The F-PDCCH carries not only dedicated information sent only to the mobile terminal receiving the F-PDCH but also common information sent to all mobile terminals. Therefore, the F-PDCCH must be broadcast in all sectors. Here, the method of broadcasting the F-PDCCH in all sectors includes a method of broadcasting through a wide beam of a conventional 120 kHz sector like F-CPICH without beamforming on a narrow beam, and F-PDCH and F on each narrow beam. There is a method of beamforming with APICH and broadcasting through all narrow beams. The F-PDCCH is demodulated using the result of estimating the channel from the pilot signal of the F-CPICH in the former method, and the channel estimation obtained from the pilot signal of the F-APICH which is beamformed in each narrow beam in the latter method. The result is demodulated.

Referring to the F-PDCH and F-PDCCH defined in the 1xEV-DV standard, as shown in FIG. 5 and FIG. 6, respectively, detailed descriptions of the FIG. 5 and FIG. 6 are provided in the 'Physical Layer Standard for cdma2000 Spread'. As it is shown in Spectrum Systems Release C ', detailed description will be omitted.

The structure of the F-APICH is not defined in the 1xEV-DV standard, but may be represented as shown in FIG. 7. The structure of the F-APICH is almost similar to the block diagram of the F-CPICH but shows a difference in the Walsh code used. The description of the Walsh code used in the F-APICH is similarly described in detail in the 'Physical Layer Standard for cdma2000 Spread Spectrum Systems Release C'.

Next, an example of implementing a beamforming with four narrow beams as four array antenna elements in one sector by multiplying the F-PDCH and the F-APICH by the same beamforming complex weight based on a general smart antenna structure will be described. Let's do it.                     

8 is a diagram illustrating an apparatus for transmitting a base station in the case where the F-PDCCH is broadcast through a wide beam and only the F-PDCH and the F-APICH are beamformed and transmitted. FIG. 11 is a diagram illustrating a base station transmitting apparatus in the case of beamforming and transmitting with F-APICH.

8 and 9, both addition and multiplication operations are complex operations, and W _m ⁽ⁿ⁾ is a beamforming complex weight of the m th antenna element multiplied by the n th input signal. In addition, two F-PDCHs and four F-APICHs are transmitted by beamforming. In the 1xEV-DV standard, a base station can transmit up to two F-PDCHs simultaneously in one sector.

Referring to FIG. 8, the F-PDCH and the F-APICH are modulated and combined by the modulation unit 810 through respective processes. The summed value is distributed for each antenna element, and the beamforming complex weight is multiplied by the distributed value. The result is a common process A in the first processor 820, and the other F-PDCH and F-APICH or other F-APICH is combined with the signals made through the same process. In this way, a signal obtained for the first time to be transmitted for each antenna element is subjected to a common process B in the second processor 830, and then the digital signal is converted into an analog signal in the transmitter 840 and power-amplified. Transmitted through the antenna element. The first processor 820 and the second processor 830 include accumulators for respective antenna paths. 9 is the same as that shown in FIG. 8 except that the F-PDCCH is included in the beamforming, a detailed description thereof will be omitted.                     

In order for the base station to use the F-APICH for beamforming, the following preconditions must be satisfied. The base station should assign different Walsh codes to the F-APICHs that are beamformed and transmitted in each narrow beam so that the mobile terminal can distinguish each F-APICH by this Walsh code and know which narrow beam it belongs to. . If the reception quality measurement value of the F-APICH of the non-serving beam is better than the communicating beam, the mobile terminal should be able to request a switch to a beam having a better reception quality. do. R-CQICH is used for this exchange request.

The R-CQICH measures the pilot signal energy versus total noise and interference density (Epilot / Nt) of the F-CPICH received from each sector constituting the packet data channel active set of the mobile terminal. The sector with the largest measurement, i.e., selects the sector with the best channel condition and transmits the interference density (Epilot / Nt) measurement received from that sector using the Walsh code assigned to that sector. If the channel condition between the mobile station and the base station is changed and a new sector is selected, the cell switching request is informed to the base station using a cell switching pattern of a predetermined type. The R-CQICH channel structure is the same as that of FIG. 10, and a detailed description of the R-CQICH is shown in 'Physical Layer Standard for cdma2000 Spread Spectrum Systems Release C'.

11 is a flowchart illustrating a reception quality index feedback operation of a reverse channel quality index channel (R-CQICH) according to beamforming of a reverse packet data channel according to an embodiment of the present invention.                     

The F-CPICH transmits without beamforming for other non-beamformed channels, and the R-CQICH provides feedback on the pilot signal of the F-CPICH.

Referring to FIG. 11, when a PDCCH control message is generated in step 1101, the base station determines whether the F-PDCH is beamfobbed in step 1102. In this case, when the F-PDCH is not beamformed, in step 1103, the base station causes the R-CQICH to feed back a channel quality indicator of the F-CPICH.

On the other hand, if the F-PDCH is beamformed, in step 1104, the base station determines whether the F-APICH is beamformed on the same path. In this case, if the F-APICH is not beamformed, the process proceeds to step 1103. Otherwise, the base station causes the R-CQICH to feed back the reception quality index of the F-APICH in step 1105.

If the F-PDCH is beamformed according to the result confirmed in step 1102, since the F-PDCH and the F-CPICH pass through different channel paths, the R-CQICH appropriately receives information about the channel path experienced by the F-PDCH. Can not feed back. Therefore, when beamforming and transmitting the F-PDCH, the R-CQICH needs to be modified to feed back information on the beamforming channel. Accordingly, the R-CQICH is modified as follows.

As described above, when the F-PDCH is transmitted without beamforming, the R-CQICH feeds back the reception quality index of the F-CPICH as before, and when the F-PDCH and the F-APICH are beamformed and transmitted, the R-CQICH is transmitted. CQICH feeds back the reception quality index of the F-APICH. Otherwise, the R-CQICH feeds back the reception quality index of the F-CPICH as before.

Next, consider the Walsh code of the R-CQICH. In the 1xEV-DV standard, there are eight Walsh codes used in the R-CQICH as shown in Table 1 below. If the F-PDCH is transmitted without beamforming, the R-CQICH feeds back a reception quality index by using a Walsh code indicating a sector which sends the F-CPICH having the best reception quality.

As shown in FIG. 12A, when all the base stations around the mobile station do not beamform the F-PDCH, the number of Walsh codes used for one-to-one mapping between the sector sending the F-CPICH and the Walsh code is insufficient. Will not.

However, as shown in FIGS. 12B and 12C, when some or all of the base stations beamform and transmit the F-PDCH, between the sector sending the F-CPICH and the narrow beam sending the F-APICH and the Walsh code. The number of Walsh codes used for one-to-one mapping may be insufficient. In order to prepare for such a case, the Walsh code needs to be increased to 16, so the Walsh cover WALSH_COVER of Table 1 is increased to 4 bits, and the Walsh code is increased from 8-ary to 16-ary.                     

Next, an apparatus for transmitting a channel quality index of a forward auxiliary pilot channel of a mobile terminal will be described with reference to the accompanying drawings.

13 illustrates an apparatus of a mobile terminal for transmitting a channel quality index of a forward auxiliary pilot channel according to an embodiment of the present invention.

Referring to FIG. 13, the apparatus for transmitting a channel quality index of a mobile terminal includes a demodulator 110 that demodulates a forward auxiliary pilot channel of serving and non-serving beams, and measures the demodulated channel quality index. And a channel quality measurer 120 for finding a beam having a channel quality index of the best forward auxiliary pilot channel, and a channel quality index coder 130 for encoding the channel quality index. Here, the channel quality index coder 130 encodes the measured channel quality index when the beam having the best channel quality is the same as the serving beam.

The apparatus for transmitting a channel quality index includes a modulator 140 for modulating the encoded channel quality index into a reverse channel and a transmitter 150 for transmitting the channel quality index included in the modulated reverse channel. .

In addition, when the beam having the best reception quality is different from a serving beam, the channel quality index transmission apparatus registers the beam having the best reception quality as a serving beam and exchanges the beam with the beam having the best reception quality. And a beam exchange code unit 150 configured to encode the channel quality index.

When the channel quality index is transmitted through a reverse dedicated control channel, the channel quality index should be included in the control message. Therefore, in this case, the control message coder 130 for encoding the control message is included. Here, it should be noted that the control message coder encodes the channel quality index coder in some cases, and is denoted by the same reference numeral in FIG. 13. These may be configured separately or may be used by changing the program in one device.

The channel quality index coder and the control message coder may include a storage unit configured to store the channel quality at a predetermined threshold value when feeding back a complete value of the channel quality measurement result, a quantizer to quantize the quantized stored channel quality, and And a channel quality index setter configured to set the channel quality index according to a comparison of the preset value or the channel quality measurement result with a preset threshold.

A method of transmitting the channel quality index to the base station through the reverse channels in the channel quality index transmission device configured as described above will be described with reference to the accompanying drawings.

14 is a diagram illustrating a process of encoding a channel quality index of a forward secondary pilot channel (F-APICH) and transmitting it to a base station through a reverse channel quality index channel (R-CQICH) according to an embodiment of the present invention.

Referring to FIG. 14, in step 1401, the mobile station demodulates F-APICHs of a serving beam and non-serving beams, and measures reception quality of each F-APICH in step 1402. In step 1403, the mobile terminal searches for a beam having the best reception quality among the measured reception qualities, and then determines in step 1404 whether the beam having the best reception quality is the same as the serving beam. If the beam having the best reception quality is the same as the serving beam, it is checked whether the mobile terminal feeds back the value of the quality measurement result received by the mobile terminal in step 1405 to a complete value. If the confirmed result is complete feedback, the mobile station stores the reception quality measurement result in the accumulator in step 1406, quantizes the reception quality measurement result into 4 bits in step 1407, and then receives the received quality index, Set to the channel quality index. Then, the mobile station modulates the channel quality index in the R-CQICH in step 1415 using the Walsh cover of the serving beam.

On the other hand, if the result of the check in step 1405, if the feedback value of the channel quality measurement results feedback in step 1409 the mobile station determines whether the first transmission. If it is the first transmission, the process proceeds to step 1406. Otherwise, in step 1410, the mobile station determines whether the channel quality measurement result is greater than a threshold stored in the accumulator. In this case, when the channel quality measurement result is larger, the mobile station sets, or encodes, the channel quality index to 1 bit, that is, "UP", indicating that the channel quality is higher than the threshold in step 1411, and storing the accumulator in the accumulator in step 1412. After increasing the threshold value, the process proceeds to step 1415. On the other hand, if the threshold is larger, the mobile station sets, i.e., encodes the channel quality index to 1 bit, i. After the threshold is decreased, the process proceeds to step 1415.

In addition, when the target beam and the serving beam are different from the result confirmed in step 1404, the mobile station registers the target beam for the serving beam in step 1420 and 1 bit as a Walsh cover of the target beam having the best reception quality in step 1421. Set the channel quality index to " 1 ". Then, the mobile station proceeds to step 1415 and modulates and transmits the 1-bit value to the R-CQICH. Is not used as "0" because is not distinguished.

Meanwhile, a channel quality indicator of the beamformed F-APICH may be fed back using a reverse dedicated control channel (R-DCCH). To this end, a new control message to be transmitted through the R-DCCH must be added. A process of transmitting a control message through the R-DCCH will be described with reference to the accompanying drawings.

FIG. 15 is a diagram illustrating a process of encoding a reception quality index of a forward auxiliary pilot channel (F-APICH) into a control message and transmitting it to a base station through a reverse dedicated control channel (R-DCCH) according to an embodiment of the present invention. .

Referring to FIG. 15, as shown in FIG. 14 in the process of transmitting a control message through the R-DCCH, steps 1401 to 1414 of FIG. 14 are performed until the encoding of the control message (step 1515). The operation is the same as in the step.

In step 1515, the mobile terminal encodes the control message according to each case and then transmits the coded control message through the R-DCCH in step 1516. The encoding operation in each of these cases will be described in more detail as follows.

First, when the beam having the best reception quality is the same as the serving beam, and the mobile terminal feeds back a complete value of the reception quality measurement result, the 2-bit type field indicating the type of channel quality index (Type) field: 00), a 4-bit Channel Quality Indicator field and a 4-bit serving beam ID field representing a serving beam are encoded in the control message.

Second, when the beam having the best reception quality is the same as the serving beam and the mobile terminal pads back the differential value of the channel quality measurement result, a 2-bit type field indicating the type of channel quality index for the first transmission. A type field (00: 00), a 4-bit Channel Quality Indicator field and a 4-bit serving beam ID field representing a serving beam are encoded in the control message. . On the other hand, after the first transmission, the 2-bit type field type field (Type field: 01) indicating the type of the channel quality index, the 4-bit channel quality index field (Channel quality indicator field), and the serving beam (serving beam) 4 A serving beam ID field of bits is encoded into a control message.

Third, if the beam having the best reception quality is different from the serving beam, the mobile station registers a target beam for the serving beam in step 1520. Then, a 2-bit type field type field (Type field: 10) indicating the type of reception quality index and a 4-bit target beam ID field indicating a target beam are encoded in the control message. .

Meanwhile, if it is difficult to modify or add the 1xEV-DV standard for the R-CQICH and the R-DCCH, a new channel may be defined. Accordingly, the mobile station sets a channel for transmitting control information related to beamforming to the base station after receiving the forward beamformed channels of the base station as a reverse beamforming control channel (R-BFCCH). Here, the R-BFCCH has a structure and a function substantially the same as that of the R-CQICH, and the major difference between the two channels is that the R-CQICH feeds back the channel quality of the F-CPICH and the R-BFCCH is beamformed. Feedback quality of the F-APICH is fed back to the base station.

Unlike the R-CQICH, since the multi-beam base station covers each sector of the existing three-sector base station with several narrow beams, the number of Walsh codes may be insufficient in the one-to-one mapping between the narrow beam sending the F-APICH and the Walsh code. , WALSH_COVER of R-BFCCH is increased to 4 bits and Walsh code is increased to 16-ary. In addition, the Walsh cover for distinguishing channels should be different. Since the R-BFCCH is a new channel, Walsh covers that are not used by other channels must be assigned. For example, the Walsh cover of R-CQICH is W12 ¹⁶ . A process of creating a control message transmitted to the base station through the R-BFCCH will be described with reference to the accompanying drawings. The process of encoding the channel quality index and transmitting the encoded channel quality index to the base station through the R-BFCCH is performed as shown in FIG. 16. Herein, the operation as shown in FIG. 16 operates in the same manner as the operation shown in FIG. 14, and since a transmitted channel is only changed from R-CQICH to R-BFCCH, a detailed operation description will be omitted. do.

On the other hand, in the detailed description of the present invention has been described with respect to specific embodiments, of course, various modifications are possible without departing from the scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, according to the present invention, the reception quality of the forward auxiliary pilot channel of the mobile terminal when beamforming and transmitting the pilot auxiliary pilot channel to each narrow beam in a high-speed data service using multiple beams By providing a channel quality indicator to the base station through reverse control channels, the base station forms an antenna beam most suitable for the mobile terminal and effectively utilizes a forward packet data channel.

Claims (19)

A mobile communication system comprising a base station having a beamforming antenna and a mobile terminal provided with a high speed data service through the beamforming antenna, wherein the mobile station transmits a channel quality index of a forward auxiliary pilot channel to the base station. In Demodulating the forward secondary pilot channels of the serving and non-serving beams to measure the channel quality index; Using the measured channel quality index to find a beam having the channel quality index of the best forward secondary pilot channel, Encoding a reception quality measurement result of the forward auxiliary pilot channel when the beam having the best channel quality is the same as the serving beam; And modulating the coded channel reception quality index into a reverse channel and transmitting the modulated signal. The method of claim 1, When the beam having the best channel quality is not the same as the serving beam, the mobile terminal registers the beam having the best reception quality as a serving beam to encode control information for exchanging the beam with the best reception quality. The method further comprises a process. The method of claim 1, wherein the encoding of the channel quality measurement result of the forward auxiliary pilot channel comprises: Storing the channel quality at a preset threshold when feeding back a complete value of the channel quality measurement result; Quantizing the stored channel quality and encoding the quantized value. The method of claim 1, wherein the encoding of the channel quality measurement result of the forward auxiliary pilot channel comprises: In case of feeding back a differential value of the channel quality measurement result, the channel quality measurement result is compared with a preset threshold value, differentially encoding the reception quality measurement result according to a comparison result, and adjusting the preset threshold value. Said method. The method of claim 4, wherein the encoding of the channel quality measurement result of the forward auxiliary pilot channel comprises: And feeding back the differential value of the channel quality measurement result, and in the first transmission, quantizes the channel quality stored as the channel quality with a preset threshold and encodes a channel quality index set as a quantized value. Way. The method of claim 1, The reverse channel is a reverse channel index channel, a reverse dedicated control channel or a reverse beamforming control channel. A mobile communication system comprising a base station having a beamforming antenna and a mobile terminal provided with a high speed data service through the beamforming antenna, wherein the mobile station transmits a channel quality index of a forward auxiliary pilot channel to the base station. In Demodulating the forward secondary pilot channels of the serving and non-serving beams to measure the channel quality index; Using the measured channel quality index to find a beam having the channel quality index of the best forward secondary pilot channel, Setting the forward secondary measured channel quality index when the beam having the best channel quality index is the same as the serving beam; Encoding the control message by including the set channel quality index in a control message; The control message is transmitted through a reverse dedicated control channel. The method of claim 7, wherein If the beam having the best channel quality is not the same as the serving beam, the mobile terminal registers the beam having the best reception quality as a serving beam and encodes control information for exchanging the beam with the best reception quality. The method characterized in that it further comprises. The method of claim 8, wherein the encoding of the control information comprises: If the beam showing the best channel quality is different from the serving beam, a 2-bit type field indicating the type of channel quality index, and a 4-bit type indicating the target beam showing the best reception quality. And a target beam ID field is coded in a control message. The method of claim 7, wherein the setting of the forward secondary measured channel quality index comprises: Storing the channel quality at a preset threshold when feeding back a complete value of the channel quality measurement result; Quantizing the stored channel quality and setting the channel quality index to a quantized value. The method of claim 7, wherein the setting of the forward secondary measured channel quality index comprises: In case of feeding back a differential value of the channel quality measurement result, the channel quality measurement result is compared with a preset threshold value, differentially encoding the measured reception quality index according to a comparison result, and adjusting the preset threshold value. Characterized in that the method. The method of claim 11, wherein the setting of the forward secondary measured channel quality index comprises: Feedback the differential value of the channel quality measurement result, and in the case of the first transmission, quantize the channel quality stored as the channel quality with a preset threshold, set the channel quality index to a quantized value, and then set the channel quality index. The method of encoding. The method of claim 7, wherein the encoding of the control message comprises: When the beam having the best channel quality is the same as the serving beam and feeds back a complete value of the channel quality measurement result, a 2-bit type field indicating the type of the channel quality index and a 4-bit channel And a 4-bit Serving Beam ID field representing a quality index field and a serving beam in a control message. The method of claim 7, wherein the encoding of the control message comprises: When the beam showing the best channel quality index is the same as the serving beam, and feeds back a differential value of the channel quality measurement result, and is not the first transmission, a 2-bit type field indicating the type of the channel quality index. And coding a 4-bit Channel Quality Indicator field and a 4-bit Serving Beam ID field representing the serving beam into a control message. The method of claim 7, wherein the encoding of the control message comprises: When the beam showing the best channel quality index is the same as the serving beam, and feeds back a differential value of the reception quality measurement result, and if it is not the first transmission, a 2-bit type field indicating the type of channel quality index The method comprising encoding a 1-bit channel quality indicator field and a 4-bit serving beam ID field representing a serving beam into a control message; In a mobile communication system comprising a base station having a beamforming antenna and a mobile terminal provided with a high speed data service through the beamforming antenna, the mobile terminal for transmitting a channel quality index of a forward secondary pilot channel to the base station In the apparatus, A demodulator for demodulating the forward auxiliary pilot channel of the serving and non-serving beams; A channel quality measurement unit for finding a beam having the channel quality index of the best forward auxiliary pilot channel using the measured channel quality index measured by the demodulated channel quality index; A channel quality index coder for encoding the measured channel quality index quality when the beam having the best channel quality and the serving beam are the same; A modulator for modulating the encoded channel quality index into a reverse channel; And a transmitter for transmitting the channel quality index included in the modulated reverse channel. The method of claim 16, If the beam having the best reception quality is different from the serving beam, the channel information index is configured by registering the beam having the best reception quality as a serving beam and encoding control information for exchanging the beam with the best reception quality. The apparatus of claim 1, further comprising a beam exchange code. The method of claim 16, And transmitting the channel quality index through a reverse dedicated control channel to include the channel quality index in a control message and to encode the control message. In a mobile communication system including a base station having a beamforming antenna and a mobile terminal provided with a high-speed data service through the beamforming antenna, the apparatus for distinguishing each narrow beam beamed by the base station and the mobile terminal In A Walsh code assignment unit for assigning different Walsh codes to the forward auxiliary pilot channel beam-formed and transmitted in each narrow beam at the base station; A forward auxiliary pilot channel modulator for modulating a forward auxiliary pilot channel with the assigned Walsh code; A forward auxiliary pilot channel demodulator for demodulating the forward auxiliary pilot channel in the mobile terminal; And a narrow beam discrimination unit that distinguishes each forward auxiliary pilot channel by the Walsh code obtained by the demodulator and recognizes which narrow beam it belongs to.

Images