KR100695673B1 - Apparatus and method for reporting, determining, and processing the downlink channel state information in wireless communication systems - Google Patents

Abstract

The present invention relates to a forward wireless communication system, and more particularly, to improve the accuracy of forward channel state information reported by a mobile station to a base station and to provide efficient packet communication by utilizing channel state information reported from the mobile station by the base station. An apparatus and method are provided.

According to the present invention, there is provided an apparatus for reporting and processing forward channel state information in a wireless communication system, comprising: carrier-to-interference ratio measuring means of a mobile terminal for obtaining forward channel state information; Channel state information generating means for determining channel state information based on the measurement value; Channel state information transmitting means for transmitting the determined channel state information to a base station; Channel state information receiving means for receiving forward channel state information of the transmitted mobile terminal; Channel state information analyzing means of a base station for processing forward channel state information of the received mobile terminal; And a forward packet transmission scheduling means of a base station for performing scheduling based on the processed information.

Channel Status Information (CSI), time delay, feedback delay, transmission delay, scheduling delay

Description

Apparatus and method for reporting, determining, and processing the downlink channel state information in wireless communication systems}

1A is a diagram of an exemplary wireless communication system.

1B is a diagram illustrating a forward channel state information report of a mobile terminal and a forward packet transmission process of a base station to which the present invention is applied.

2A illustrates an apparatus and method for reporting and processing forward channel state information of a mobile station and a base station in a wireless communication system to which the present invention is applied.

2b is a diagram illustrating a process and an apparatus for generating channel state information in a mobile terminal to which the present invention is applied;

2c is a diagram illustrating a process and apparatus for interpreting channel state information in a base station to which the present invention is applied.

3 is a diagram illustrating a time delay between reporting time of a channel state information and using time according to the first embodiment of the present invention.

4 is a diagram illustrating a time delay between reporting time of a channel state information and a using time according to a second embodiment of the present invention.

5 is a diagram illustrating a time delay between reporting time of a channel state information and using time according to a third embodiment of the present invention.

The present invention relates to a forward wireless communication system, and more particularly, to improve the accuracy of forward channel state information reported by a mobile station to a base station, and to provide efficient packet communication by using channel state information reported from the mobile station at the base station. An apparatus and method are provided.

Currently, the mobile communication system is evolving from the initial voice-oriented service to a high-speed, high-quality wireless data packet communication system capable of providing data and multimedia services. Based on the radio channel information periodically provided by the mobile terminal to support forward high speed data packet transmission, the base station determines the channel status of the mobile terminals to select a good mobile terminal to receive the forward packet transmission service, and selects a channel of the selected mobile terminal. Considering the situation, the transmission rate, coding rate, and modulation scheme are adaptively determined to maximize forward transmission capability.

Key technologies related to this are performance enhancement techniques such as fast scheduling, adaptive modulation and coding (AMC), and hybrid automatic repeat request (H-ARQ).

In the high-speed, high-quality wireless data packet communication system, the base station utilizes the performance enhancement techniques listed above to schedule transmission of data packets according to the quality of the forward channel and determine transmission parameters to enable high-speed packet data service.

That is, a mobile terminal having a good forward channel state is selected among a plurality of mobile terminals communicating on the basis of the forward channel state information, and transmission parameters suitable for the channel situation of the mobile terminal (for example, data rate). A code rate and a modulation method are determined. Acquiring multi-user diversity through fast scheduling among a plurality of mobile terminals, and adaptively determining a transmission scheme according to a forward channel state between the selected mobile terminal and a base station that is wirelessly connected to the entire system. Improve the efficiency. Therefore, accurate forward channel state information must be provided in order for the base station to effectively utilize fast scheduling and adaptive modulation and coding techniques.

1A is a diagram of an exemplary wireless communication system. Referring to FIG. 1A, the wireless communication system 100 may include a base station 110 and a plurality of mobile terminals 120, 130, and 140. In an exemplary diagram, mobile terminals and a base station transmit and receive data through a forward channel 115 that shares and communicates with a plurality of mobile terminals and a reverse channel 125, 135, 145 that communicates individually with each mobile terminal. can do.

1B is a diagram illustrating a transmission and reception process between mobile stations and a base station in a wireless communication system to which the present invention is applied. Referring to FIG. 1B, the base station 110 is notified of the forward channel status of the mobile terminals 120, 130, and 140 through the reverse channels 125, 135, and 145, and collected through the reverse channel. Based on the forward channel state information, a data packet to be delivered to the mobile terminal is transmitted through the forward channel 115 when there is a mobile terminal having a good channel condition through fast scheduling, adaptive modulation, and encoding.

Forward channel state information (CSI) is used by a base station to determine a packet modulation and coding scheme (MCS). The base station selects an MCS having a high data rate if the state of the forward channel is good. On the contrary, if the state of the forward channel is poor, the MCS having a low data rate is selected and transmitted. Typically used in determining the quality of the forward channel is the received signal-to-noise ratio (SNR) measured for the downlink pilot channel. The mobile station determines channel state information to inform the base station through the received signal-to-noise ratio measurement measured by the mobile station. The signal-to-noise ratio in the mobile terminal is similarly signal-to-interference and noise ratio (SINR), carrier-to-interference ratio (C / I), Measurements such as received signal strength indication (RSSI) may be considered, and the present invention will be exemplarily referred to the carrier-to-interference ratio.

In determining the forward channel state information, the mobile station determines the quality of the forward channel through the carrier-to-interference ratio measurement and determines the channel state information to ensure constant reception performance according to the demodulation and decoding performance of the mobile station. Report to the base station. If the mobile station simply determines the channel state information and transmits the information to the base station, the mobile terminal demodulation and decoding performance may not be considered. That is, when the demodulation and decoding performance of the mobile terminal is good in the same channel state, it may be able to support higher MCS than the mobile terminal having poor performance.

However, when reporting information on the carrier-to-interference ratio as channel state information, it is impossible to consider the performance difference of the mobile terminals because the base station cannot know the performance difference of the mobile terminals. Therefore, the mobile terminal preferably generates channel state information in consideration of its demodulation and decoding performance. The mobile stations observe the current channel quality by measuring the received carrier-to-interference ratio, and determine the maximum acceptable transmission scheme as the channel state information in consideration of the measured channel quality and the demodulation and decoding performance of the mobile station itself. In other words, the mobile station reports the maximum acceptable limit to the base station, and the base station determines a transmission scheme that can improve the system performance based on the capacity of the base station and the channel state information reported by the mobile station.

As described above, the radio resource allocation for the forward channel operation of the base station is controlled based on the channel state information reported through the mobile terminal. Therefore, the accuracy of channel state information is an important factor in determining performance in a forward wireless communication system utilizing high-speed scheduling and adaptive modulation and coding techniques. If distortion occurs in the channel state information, the transmission method is determined based on the wrong channel quality information, which causes a waste of forward wireless transmission resources, resulting in a problem of deteriorating system efficiency.

Accordingly, an object of the present invention, which was devised to supplement the problems of the prior art operating as described above, is to provide an apparatus and method for ensuring high accuracy when acquiring channel state information in a forward wireless communication system.

Another object of the present invention is to provide a method for the mobile terminal to determine channel state information to enable efficient forward packet transmission in a forward wireless communication system.

It is still another object of the present invention to provide a method for a base station to process channel state information to enable efficient forward packet transmission scheduling based on channel state information reported from a mobile terminal in a forward wireless communication system.

A final object of the present invention is to provide a base station to enable efficient forward packet transmission scheduling based on a channel state information determined by a mobile terminal and efficient channel packet transmission information reported by the mobile terminal to enable efficient forward packet transmission in a forward wireless communication system. The present invention provides a method for processing channel state information.

The apparatus of the present invention for achieving the above objects is

An apparatus for reporting and processing forward channel state information in a wireless communication system, comprising: carrier-to-interference ratio measuring means of a mobile terminal for obtaining forward channel state information; Channel state information generating means of the mobile terminal for determining channel state information based on the measurement value; Channel state information transmitting means for transmitting the determined channel state information to a base station; Channel state information receiving means for receiving forward channel state information of the transmitted mobile terminal; Channel state information analyzing means of a base station for processing forward channel state information of the received mobile terminal; And forward packet transmission scheduling means of the base station performing scheduling based on the processed information.

The method of the present invention for achieving the above objects is

A method for reporting and processing forward channel state information in a wireless communication system, comprising: a carrier-to-interference ratio measurement process of a mobile terminal for obtaining forward channel state information; Generating channel state information of the mobile terminal to determine channel state information based on the measured value; Transmitting channel state information for transmitting the determined channel state information to a base station; Receiving channel state information for receiving forward channel state information of the transmitted mobile terminal; Analyzing channel state information of a base station processing forward channel state information of the mobile station; And a forward packet transmission scheduling process of the base station which performs scheduling based on the processed information.

Exemplary embodiments of the present invention will be more fully understood from the detailed description provided below and the accompanying drawings, in which like elements are designated by like reference numerals. In the present specification, exemplary embodiments are described with reference to the accompanying drawings, but the apparatus and method according to the present invention are not limited to the embodiments, and various changes are made by those skilled in the art without departing from the spirit and scope of the present invention. It can be changed and modified. Accordingly, all such changes and modifications are intended to fall within the scope of the spirit of the invention as defined by the appended claims.

FIG. 2A illustrates an apparatus and method for reporting and processing forward channel state information of a mobile station and a base station in a wireless communication system to which the present invention is applied.

Referring to FIG. 2A, in order for the mobile terminals 120, 130, and 140 to obtain forward channel state information, the carrier-to-interference ratio is measured using the forward channel 115 or the forward pilot channel 200. The base station 110 transmits the forward channel state information through the reverse channel 125, 135, and 145 through the means 210, means 220 for generating channel state information, and means 230 for transmitting channel state information. To send.

Referring to FIG. 2A, the base station 110 acquires the forward channel state information and reflects it in the packet transmission scheduling. The forward channel is transmitted through the channel state information receiving unit 240 and the channel state information analyzing unit 250. When the state information is obtained, the data packet is transferred to the selected mobile terminal 120, 130, or 140 through the forward channel 115 through the forward packet transmission scheduling means 260 and the forward data packet transmission means 270. send.

Referring to Figure 2a briefly describes the operating principle of the present invention. As described above, the wireless communication system to which the present invention is applied is greatly influenced by the accuracy of channel state information reporting. There are many factors that affect the accuracy of channel state information, but representative examples may include channel state reporting period and time delay, accuracy of channel estimation, and reliability of channel state reporting path. In the present invention, the accuracy of the channel estimation and the reliability of the channel state reporting path will not be mentioned because they may unnecessarily obscure the gist of the present invention. According to the present invention, the channel state information is considered in consideration of a time delay occurring in the process of transmitting the forward channel state information to the base station through the reverse channel and transmitting the forward channel state information to the mobile station through the forward channel based on the reported packet transmission. The present invention proposes a device and a method of using the device correctly.

2B is a diagram illustrating a process and an apparatus for generating channel state information in a mobile terminal to which the present invention is applied.

Referring to FIG. 2B, the mobile terminal receives the forward channel information 221 from the means for measuring the carrier-to-interference ratio 210 and generates the channel state information through the means 220 for forward channel information 223. It generates and delivers to the means 230 for transmitting the channel state information.

Specifically, the means for generating the channel state information 220, the performance degradation compensation value corresponding to the means for processing the forward channel information 222, the delay time measurement means 280, the time delay 285 of the mobile terminal Means 224, 225, 226, 227, 228, 229 to adjust the pressure. In the means for adjusting the performance deterioration compensation value, the compensation value provided by the means for setting the initial value 224 is increased in the compensation value changing condition determining means 225 according to the observation period determined by the changing condition observation period adjusting means 229. 226, maintenance 227, and reduction 228 may be determined and adaptively adjusted according to a mobile terminal situation such as a channel situation and a mobile environment.

As a delay factor corresponding to a delay time to be calculated by the delay time measuring means, a transmission delay, a scheduling delay, a time lapse of channel state information, etc. are considered. The transmission delay includes a delay that occurs during the transmission and reception process of the transmission packet and a propagation delay in the radio. Except for the short time propagation delay, the transmission delay may be set as a predicted value through repeated measurement in the mobile terminal. The delay is a time required for the base station to perform scheduling based on the received information and to transmit a data packet to the mobile terminal according to the scheduling result. The mobile terminal may receive and receive a design value required by the base station at the beginning of communication. . The system value considering the time required for such scheduling is determined before the actual communication is started by the communication system standard. However, since the elapsed time of the channel state information means the elapsed time until the base station receiving the channel state information is scheduled using the actual information, the mobile station cannot measure the elapsed time of the channel state information.

The compensation value is a configuration value that is adaptively changed according to a channel condition in the mobile terminal, and a conditional expression corresponding to a compensation value change condition may exist in various forms. For example, whether a data packet (or frame) is received or a channel The trend of the change of state information can be considered.

First, for example, when a compensation value change condition is set based on whether a data packet is received, a method of maintaining or decreasing the compensation value upon successful data packet reception may be considered. This is a change condition for increasing the compensation value so as to minimize the unnecessary compensation by maintaining or decreasing the compensation value when the data packet reception is successful, and increasing the probability of success in receiving the next packet when the data packet reception fails.

For example, when a compensation value change condition is set based on a change in channel state information, a method of reducing the compensation value when the channel condition is improved, maintaining the same value and increasing it when it is worsened may be considered. This is a change condition for lowering the compensation effect when the channel state information is improved and increasing the compensation effect when it is worsened. The compensation value changing condition described in the illustrative example may be summarized as in Equations 1 and 2 below.

Equation 1 and Equation 2 denote the observation period determined by the change condition observation period adjusting unit 229. In addition, it may be considered to operate without the compensation value change condition determining means 225 and the change condition observation period adjusting means 229, in which case the operation is performed by the initial compensation value provided by the initial value setting means 224. .

2C is a diagram illustrating a process and apparatus for interpreting channel state information in a base station to which the present invention is applied.

Referring to FIG. 2C, the base station receives the forward channel information 251 from the means 240 for receiving the channel state information, and generates the forward channel information 253 through the means 250 for interpreting the channel state information. Forward to forward means 270 for forwarding data packets.

Looking at the means 250 for interpreting the channel state information in detail, the performance degradation compensation value corresponding to the means for analyzing the forward channel information 252, the delay time measuring means 290, the time delay 295 of the base station is adjusted Means 254, 255, 256, 257, 258, and 259. In the means for adjusting the performance deterioration compensation value, the compensation value provided by the initial value setting means 254 is increased by the compensation value changing condition determining means 255 according to the observation period determined by the change condition observation period adjusting means 259. A determination may be made at 256, maintenance 257, and reduction 258 to adaptively adjust to the situation of the mobile terminal, such as a channel situation and a mobile environment. Detailed operation principle of the base station is made similar to the above-described mobile terminal, so a detailed description thereof will be omitted.

Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention.

First Embodiment

As described above, in the process of forwarding and scheduling the forward channel state information to the base station, packet transmission is performed, a time delay between the report time point and the channel state information inevitably occurs. Therefore, the accuracy of the forward channel state information of the mobile terminal is degraded due to this time delay, so that the mobile terminal determines the forward channel state information as shown in Equation 3 in consideration of this time delay.

3 is a diagram illustrating a delay between a channel state information report time point and a use time point according to the first embodiment of the present invention.

Referring to Equation 3 and FIG. 3, a time delay including transmission delays 320 and 340 and a scheduling delay 330 occurring between channel state information reporting and data packet transmission in a wireless communication system to which the present invention is applied. In consideration of 350, the mobile terminal 120 removes by the performance degradation compensation value corresponding to the time delay 350 from the value obtained from the received carrier-to-interference ratio to determine the forward channel information. Perform the process of determining.

As described above, the first embodiment of the present invention provides a method for the mobile terminal to determine channel state information to enable efficient forward packet transmission in a forward wireless communication system.

Second Embodiment

While the first embodiment has provided an example of a method of increasing the accuracy of channel state information in a mobile terminal, the second embodiment provides an example of a method of increasing the accuracy of channel state information in a base station. In the first embodiment, it is not necessary to consider the effect on the reporting period of the forward channel state information of the mobile terminal, in the second embodiment to increase the accuracy of the channel state information in the base station in consideration of the effect.

In the first embodiment, since the forward channel state information report is made in every packet transmission unit, the channel information error of the mobile terminal received from the base station may be relatively low. In the second embodiment, the forward channel state information report is longer than the packet transmission unit. In this case, the channel information error of the mobile terminal occurs relatively severely. In the process of forwarding and scheduling the forward channel state information to the base station, the base station may prevent the accuracy of the forward channel state information of the mobile terminal from falling due to a time delay between reporting and using the channel state information. As shown in Equation 4, forward channel state information is processed.

4 is a diagram illustrating a delay between a channel state information report time point and a use time point according to a second embodiment of the present invention.

Referring to Equation 4 and FIG. 4, transmission delays 420 and 450, scheduling delays 440, and channel state information that occur between channel state information reporting and data packet transmission in a wireless communication system to which the present invention is applied. In consideration of the time delay 460 including the time lapse 430 of FIG. 1, the time delay is determined from the information obtained by receiving the forward channel state information of the mobile station 120 from the base station 110 to process the forward channel information. A process of processing forward channel information is performed by removing a performance degradation compensation value corresponding to 460.

In the second embodiment, the relationship between the channel state information reporting time point and the use time point is influenced according to the forward channel state information reporting period of the mobile terminal, but the mobile terminal can know when the forward channel state information currently transmitted will be used. Since this cannot be taken into consideration, it is different from the first embodiment in that the base station compensates.

As described above, the second embodiment of the present invention provides a method for a base station to process channel state information to enable efficient forward packet transmission scheduling based on channel state information reported from a mobile terminal in a forward wireless communication system.

Third Embodiment

In the first and second embodiments, a method of increasing the accuracy of channel state information is independently performed by the mobile terminal or the base station. In the third embodiment, the mobile terminal and the base station are simultaneously executed. The third embodiment mixes the channel state determination method of the mobile terminal of the first embodiment and the channel state processing method of the base station considered in the second embodiment, and combines the functions of the first and second embodiments to provide the mobile terminal and the base station. It was proposed to complement each other.

In the first embodiment, the mobile terminal considers transmission delay and scheduling delay inevitably occurring in the process of exchanging channel information between the mobile station and the base station. In the second embodiment, the channel caused by the channel state information reporting period is considered. Since the mobile terminal cannot know the elapsed time of the state information, the base station processes the reported channel information in consideration of this. In the third embodiment, only the elapsed time of the channel state information is additionally considered while the base station processes the channel information report of the mobile terminal described above in the first embodiment. In the process of forwarding and scheduling the forward channel state information to the base station, the base station may prevent the accuracy of the forward channel state information of the mobile terminal from falling due to a time delay between reporting and using the channel state information. As shown in Equation 5, forward channel state information is processed.

5 is a diagram illustrating a delay between a channel state information report time point and a use time point according to the third embodiment of the present invention.

Referring to Equation 5 and FIG. 5, a time delay including transmission delays 520 and 550 and scheduling delays 540 occurring between channel state information reporting and data packet transmission in a wireless communication system to which the present invention is applied. In consideration of 560, the mobile terminal 120 performs a process of determining forward channel information, and the base station 110 considers a time delay 570 corresponding to the time lapse 530 of the channel state information. In order to process the forward channel information, a process of processing forward channel state information of the mobile terminal 120 is performed by reducing the compensation value corresponding to the time lapse 530 of the channel state information from the information received from the base station. The third embodiment differs from the first and second embodiments in that the mobile terminal considers the effects of transmission delay and scheduling delay, and the base station additionally considers only the effect of channel state information over time. .

As described above, the third embodiment of the present invention provides an efficient forward packet based on a method of determining channel state information by the mobile terminal and efficient channel state information reported from the mobile terminal to enable efficient forward packet transmission in the forward wireless communication system. A base station provides a method of processing channel state information to enable transmission scheduling.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

The present invention has an effect of increasing the accuracy of the forward channel state information shared by the mobile station and the base station in the forward wireless communication system using the forward packet transmission scheduling, and thereby increasing the scheduling efficiency.

Claims (5)

An apparatus for reporting and processing forward channel state information in a wireless communication system, Carrier-to-interference ratio measuring means of the mobile terminal for obtaining forward channel state information; Channel state information generating means of the mobile terminal for determining channel state information based on the measurement value measured by the measuring means; Channel state information transmitting means for transmitting the determined channel state information to a base station; Channel state information receiving means for receiving forward channel state information of the mobile terminal transmitted from the channel state information transmitting means; Channel state information analyzing means of a base station for processing forward channel state information of the received mobile terminal received by the channel state information receiving means; And And reporting and processing forward channel state information in a wireless communication system including forwarding packet transmission scheduling means of a base station performing scheduling based on the processed information. A method for reporting and processing forward channel state information in a wireless communication system, A carrier-to-interference ratio measurement process of a mobile terminal for obtaining forward channel state information of wireless communication; Generating channel state information of the mobile terminal to determine channel state information based on the measured values measured in the measurement process; Transmitting channel state information for transmitting the determined channel state information to a base station; Receiving channel state information for receiving forward channel state information of the mobile terminal transmitted in the channel state information transmission process; A channel state information analysis process of a base station processing forward channel state information of the mobile terminal received in the process of receiving the channel state information; And And reporting and processing channel state information in a wireless communication system including a forward packet transmission scheduling process of a base station performing scheduling based on the processed information. A method for determining channel state information reported by a mobile station to a base station in a wireless communication system, Time delay between reporting and using channel state information in the forward channel information obtained by the mobile terminal using measurements including signal-to-noise ratio, signal-to-interference and noise ratio, carrier-to-interference ratio, and received signal strength. Predicting forward channel information in consideration of a compensation value given as an initial setting value; The mobile terminal adaptively changing a compensation value for predicting forward channel information in the mobile terminal according to a channel condition by determining a change condition; And Determining, by the mobile terminal, channel state information in a wireless communication system including a part or all of adjusting a change condition observation period required for determining a change condition of a compensation value for predicting forward channel information in the mobile terminal. Way. A method for processing channel state information reported by a base station from a mobile terminal in a wireless communication system, Processing, by the base station, the forward channel state information in consideration of the time delay between the reporting time and the use time of the channel state information and the compensation value given as an initial setting value in the forward channel state information received from the mobile terminal; Adaptively changing, by the base station, a compensation value for processing forward channel information at a base station according to a channel condition by determining a change condition; And a base station having all or a part of adjusting a change condition observation period necessary for determining a change condition of a compensation value for processing forward channel information at the base station. In the method of the mobile terminal and the base station to cooperate with each other to determine and process the channel state information Forward channel information obtained from the mobile terminal and the base station by the mobile terminal and the base station using measurements including signal-to-noise ratio, signal-to-interference and noise ratio, carrier-to-interference ratio, and received signal strength Predicting and processing forward channel information in consideration of the time delay between the channel state information reporting time point and the use time point and the compensation value given as an initial setting value; Adaptively changing, by the mobile terminal and the base station, a compensation value for predicting forward channel information in the mobile terminal and a compensation value for processing forward channel information in the base station according to a channel condition by changing condition determination; And All or part of the process of the mobile terminal and the base station adjusting the change condition observation period necessary for determining the change condition of the compensation value for the forward channel information prediction in the mobile terminal and the compensation value for the forward channel information processing in the base station A method for determining and processing channel state information in a wireless communication system comprising the step of providing.

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