JP2009153204A - Communication system, mobile station, base station, transmission control method, and signal processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for grouping a plurality of slots two-dimensionally arranged in a frequency direction and a time direction in response to the state of a propagation path into in at least any one of the frequency direction and the time direction, and transmitting control information for each of the plurality of grouped slots. <P>SOLUTION: A control device for grouping control information controls the control information notification unit of a plurality of slots which are two-dimensionally arranged in a frequency direction and a time direction, where a slot defined by a predetermined time length and a predetermined frequency band is used as a minimum unit of control information notification. In the device, a grouping selection section 210 inputs an estimated value of variation in a propagation path, and selects a grouping system for grouping the plurality of slots into the control information notification units configured by an arrangement of one slot or more in the frequency direction and one slot or more in the time direction based on the estimated value of variation in the propagation path. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to transmission of propagation path information for each group including one or more subcarriers in an orthogonal frequency division multiplexing system.

  2. Description of the Related Art In recent years, there has been a demand for speeding up of wireless communication systems, and a multi-carrier transmission system that performs communication by carrying information on a plurality of carriers is attracting attention as one of methods that can realize speeding up and large capacity. The Orthogonal Frequency Division Multiplex (OFDM) system, which is a type of multicarrier transmission system, can reduce the interval between subcarriers that are orthogonal to each other, so that the frequency utilization efficiency is high and is added to the head of the symbol string. This is one of the most effective modulation schemes for wideband wireless communication systems because the guard interval is highly resistant to multipath fading.

  When performing broadband transmission by single carrier transmission, the frequency characteristics of the entire band are not flat due to the influence of frequency selective fading. This corresponds to the occurrence of intersymbol interference in the time domain, which causes a significant deterioration in transmission quality. On the other hand, in the OFDM scheme, even in a frequency selective fading environment, the propagation path fluctuation of each subcarrier can be regarded as uniform fading, and thus the influence of frequency selective fading can be reduced.

  Further, due to the influence of frequency selective fading, the propagation path environment of each subcarrier, for example, the signal-to-noise ratio (SNR) is different for each subcarrier in different environments. Instead of using the multi-level modulation method, an adaptive modulation method (subcarrier adaptive modulation method) that gives an appropriate modulation parameter for each subcarrier according to the channel state is applied. For example, for subcarriers with large received power Frequency utilization efficiency can be improved by using a large multilevel 64QAM (Quadrature Amplitude Modulation) and a small multilevel BPSK (Binary Phase Shift Keying) for low subcarriers.

  However, the method of giving the modulation parameter for each subcarrier requires notification of the modulation parameter and propagation path information for each subcarrier between the transmitter and the receiver. As the number of subcarriers increases, the amount of information that must be notified also increases, so that the ratio of control information to the limited communication capacity increases and transmission efficiency decreases.

  In order to solve this problem, Non-Patent Document 1 proposes a method of grouping a plurality of subcarriers. In Non-Patent Document 1, a certain number of subcarriers are grouped to reduce the amount of control information, and the number of subcarriers in the group is studied. FIG. 3 shows an example of subcarrier grouping.

  A method of adaptively changing the number of subcarriers included in a group according to a change in propagation path environment has been devised (Patent Document 1). An example of a system disclosed in Patent Document 1 is shown in FIG. Among these, the control unit 752 included in the mobile station 750 collects subcarriers whose received power difference falls within a required threshold and controls the number of groups to be minimized, thereby reducing the amount of notification information. ing.

  As another conventional method, in a system that applies adaptive modulation to single carrier transmission, when the propagation path environment changes, the mobile station requests the base station to change the modulation method and moves if the base station gives permission. A method is disclosed in which information on a propagation path is notified from a station to a base station, and the base station determines a modulation method based on propagation path information notified from a mobile station (Patent Document 2). An example of a system disclosed in Patent Document 2 is shown in FIGS. 20 shows the overall configuration of mobile device 800, and FIG. 21 shows the configuration of channel quality measurement section 806. In the mobile station 800, the channel quality measurement unit 806 measures the channel status, and if the measured channel status is determined to have changed in the channel status determination unit 806c, a signal for requesting a modulation scheme change is generated and transmitted to the base station. Sent. At this time, the mobile station selects the modulation scheme and notifies the base station, but the base station may determine the modulation scheme by notifying the base station of the channel quality.

Japanese Patent Laid-Open No. 2003-169036 JP 2004-23145 A

Tsuji, Naganaga, Mori, Kobayashi, “Study on Burst Mode OFDM Communication System Using Adaptive Modulation”, IEICE, IEICE Technical Report RCS2001-109, pp51-57, September 2001

  However, the communication capacity that can be transmitted from the mobile station to the base station is limited, and in order to suppress overhead, it is necessary to limit the amount of control information notified from the mobile station to the base station. That is, the maximum number of groups in grouping for control information notification is limited by the control channel capacity from the mobile station to the base station.

  In such a system, in the conventional method of grouping a certain number of subcarriers, the propagation path characteristics of each subcarrier in the group are greatly different when fading fluctuations between the subcarriers are severe as shown in FIG. . FIG. 22 is a diagram illustrating an example of grouping in the frequency direction on a propagation path having a large frequency variation in the propagation path and a small time variation. For this reason, when the reception SNR of the subcarrier in the group is notified as the propagation path information, even if there is a subcarrier with a good reception environment in the group in order to satisfy the required quality, the modulation parameter of the low transmission rate Therefore, the frequency utilization efficiency is lowered. On the other hand, when reporting the average reception SNR of all subcarriers in the group, the modulation parameter of the same transmission rate as other subcarriers in the group is applied to subcarriers with a poor reception environment. The problem of not meeting the required quality arises.

  As in the conventional example shown in FIG. 19, in the method of controlling subcarriers in which the difference in received power falls within a required threshold and controlling the number of groups to be minimum, fading fluctuations between subcarriers are severe. In addition, the number of subcarriers to be grouped decreases, and the amount of control information that must be notified increases. In a system with an upper limit on the amount of control information, there is a possibility that the difference in received power of each subcarrier in the group may not satisfy a required threshold. Similar problems arise.

  Further, since the conventional example shown in FIG. 19 does not have a block for measuring propagation path fluctuation, it does not take into account time fluctuation of the propagation path. That is, as shown in FIG. 22, grouping is selected at a constant period and modulation parameters are selected, so that the control information to be notified is almost the same every time in an environment where the time variation of the propagation path is small. For this reason, there exists a problem that the efficiency of control information notification is bad.

  In the conventional example shown in FIG. 20, since the mobile station determines the timing for switching the modulation scheme according to the time variation of the propagation path environment, it is not necessary to notify the control information used for modulation scheme selection during the period when the modulation scheme is not switched. There is an advantage of being good. However, in this conventional example, no consideration is given to reducing the amount of control information in a multicarrier communication system. Even when the disclosed subcarrier grouping is applied, control information corresponding to the number of subcarriers or the number of groups must be transmitted when switching the modulation scheme. For this reason, when assuming a system in which a channel for notifying control information is allocated with a certain capacity, there is an upper limit on the capacity of the control channel, and therefore, disclosed in Patent Document 1 and Patent Document 2 when switching the modulation method The same problem as in the conventional example occurs.

  The present invention has been made in view of such circumstances, and a plurality of slots arranged two-dimensionally in the frequency direction and the time direction are arranged in at least one of the frequency direction and the time direction according to the propagation path state. It is an object of the present invention to provide an apparatus and a method for reporting control information for each of a plurality of slots grouped into groups.

  (1) One aspect of the modulation control apparatus according to the present invention is a plurality of two-dimensional arrangements in the frequency direction and the time direction, with a slot defined by a certain time length and a certain frequency band as a minimum control information notification unit. Control information grouping control apparatus for controlling a control information notification unit of a plurality of slots, receiving a propagation path fluctuation estimated value, and, based on the propagation path fluctuation estimated value, one or more slots in the frequency direction and one in the time direction. A grouping selection unit that selects a grouping method for grouping a plurality of slots into the control information notification unit configured by the above-described slot arrangement is provided.

  Thus, according to one aspect of the control information grouping control apparatus of the present invention, a plurality of slots can be grouped into a two-dimensional array in the frequency direction and the time direction. Thereby, the amount of control information notified from the mobile station to the base station can be reduced. In addition, a plurality of slots are grouped adaptively in the time direction and the frequency direction based on the propagation path fluctuation, thereby suppressing variations in the propagation path conditions of the slots in the group. Thereby, since an appropriate modulation system can be adopted, the transmission rate can be increased and the communication quality can be improved.

  (2) Further, another aspect of the control information grouping control apparatus of the present invention uses a slot defined by a certain time length and a certain frequency band as a minimum control information notification unit, and has a frequency direction and a time direction. A control information grouping control apparatus for controlling control information notification units of a plurality of slots arranged in a two-dimensional array, wherein propagation path information indicating propagation path conditions is input, and based on the propagation path information, A propagation path fluctuation estimation unit for estimating a propagation path fluctuation estimation value indicating fluctuation, and a control composed of an array of one or more slots in the frequency direction and one or more slots in the time direction based on the propagation path fluctuation estimation value And a grouping selection unit that selects a grouping method for grouping a plurality of slots into an information notification unit.

  Thus, according to another aspect of the control information grouping control apparatus of the present invention, a plurality of slots can be grouped into a two-dimensional array in the frequency direction and the time direction. Thereby, the amount of control information notified from the mobile station to the base station can be reduced. Moreover, a propagation path fluctuation estimated value can be estimated based on propagation path information.

  (3) Furthermore, according to yet another aspect of the control information grouping control apparatus according to the present invention, a slot defined by a certain time length and a certain frequency band is a minimum modulation unit, and the frequency direction and the time direction are Control information grouping control device for controlling the modulation units of a plurality of slots arranged in two dimensions, and input movement speed information indicating the movement speed of the receiver, based on the magnitude of the movement speed, A propagation path estimator for estimating a propagation path fluctuation estimation value indicating fluctuations in the propagation path situation, and an array of one or more slots in the frequency direction and one or more slots in the time direction based on the propagation path fluctuation estimation value And a grouping selection unit that selects a grouping method for grouping a plurality of slots into a modulation unit.

  Thus, according to the aspect of the control information grouping control apparatus of the present invention, the moving speed can be used as the propagation path state. As a result, even when the moving speed of the mobile station is significant, when the grouping method is selected, it is possible to realize grouping that more appropriately reflects fluctuations in the propagation path condition.

  (4) Another aspect of the control information grouping according to the present invention is that a slot defined by a certain time length and a certain frequency band is a minimum control information notification unit, and is two-dimensionally in the frequency direction and the time direction. A control information grouping control apparatus for controlling control information notification units of a plurality of slots arranged, a control information storage unit for storing control information indicating past propagation path conditions, and control information indicating current propagation path conditions And using the past control information and the current control information, a propagation path fluctuation estimation unit for estimating a propagation path fluctuation estimation value indicating a fluctuation of a propagation path condition, and using the propagation path fluctuation estimation value A grouping selection unit for selecting a grouping method for grouping a plurality of slots into a control information notification unit configured by an array of one or more slots in the frequency direction and one or more slots in the time direction; Characterized in that it comprises.

  Thus, according to another aspect of the control information grouping control apparatus according to the present invention, a plurality of slots can be grouped into a two-dimensional array in the frequency direction and the time direction. Thereby, the amount of control information notified from the mobile station to the base station can be reduced. Also, the processing load on the mobile station side can be reduced by selecting the grouping method on the base station side and notifying the mobile station. Further, by grouping a plurality of slots adaptively in the time direction and the frequency direction based on the propagation path fluctuation, it is possible to suppress variations in the propagation path conditions of the slots in the group. Thereby, since an appropriate modulation system can be adopted, the transmission rate can be increased and the communication quality can be improved.

  (5) The control information grouping control apparatus according to the present invention is characterized in that the grouping selection unit makes the number of slots constituting a modulation unit constant.

  Thus, when the number of slots in a group is made constant, the amount of control information in each transmission unit can be made constant by transmitting from the mobile station to the base station. In particular, when the number of slots in a group is fixed and multiple slots are grouped in the time direction, the amount of control information increases as the number of groups in the frequency direction increases, but the control information is divided by elements in the time direction. Then, the amount of control information in each transmission unit can be made constant by transmitting from the mobile station to the base station in a plurality of times. As a result, the control channel can be used to the maximum extent in a communication system in which a control channel with a certain capacity is secured in advance.

  (6) In the control information grouping control apparatus according to the present invention, the grouping selection unit increases the number of slots in the time direction when the propagation path fluctuation estimated value is larger than a predetermined threshold, and the propagation path fluctuation estimated value The number of slots in the frequency direction is increased when is less than or equal to a predetermined threshold value.

  As described above, an appropriate modulation scheme can be adopted by grouping a plurality of slots adaptively in the time direction and the frequency direction based on the propagation path fluctuation. Thereby, the transmission rate can be increased and the communication quality can be improved.

  (7) Further, according to one aspect of the control information notification control apparatus of the present invention, a slot determined by a certain time length and a certain frequency band is a minimum control information notification unit, and one or more slots and time in the frequency direction are used. A control information notification control apparatus for controlling transmission of control information for each control information notification unit configured by an array of one or more slots in a direction, wherein a plurality of slots are grouped into the control information notification unit A channel information for each slot, and using the channel information for each slot, a control information generator for generating control information indicating a channel status for each control information notification unit, And a control information transmission control unit for instructing a timing for transmitting the generated control information to the control information generation unit.

  Thus, according to one aspect of the control information notification control apparatus according to the present invention, it is possible to generate control information including propagation path information for each control information notification unit. In addition, the timing for transmitting the generated control information can be controlled. Accordingly, the mobile station can notify the base station of propagation path information for each group of control information notification units grouped.

  (8) In the control information notification control apparatus according to the present invention, the control information generation unit divides the control information by the number of slots in a time direction constituting a control information notification unit, and the control information transmission control unit The transmission timing is instructed for each of the divided control information.

  As described above, when a plurality of slots are grouped in the time direction, the control information is divided into a plurality of times and transmitted from the mobile station to the base station, thereby making the amount of control information in each transmission unit constant. be able to. As a result, the control channel can be used to the maximum extent in a communication system in which a control channel with a certain capacity is secured in advance.

  (9) In the control information grouping control apparatus according to the present invention, the control information generation unit corresponds to a first slot in a time direction constituting a control information notification unit as propagation path information of each of a plurality of slots. Propagation path information is used.

  In this way, when a plurality of slots are grouped in the time direction, the propagation path status of the first slot can be notified to the base station.

  (10) In the control information grouping control apparatus according to the present invention, the control information generation unit divides the control information of each of the plurality of control information notification units into a plurality of control information, and divides the control information divided into the plurality of control information notification units. The combined composite control information is generated, and the control information transmission control unit instructs the timing for transmitting the composite control information.

  Thus, by dividing the control information into a plurality of notifications, the amount of control information to be notified at a time can be adjusted. Also, when there are multiple groups in the frequency direction, the propagation path information of all groups can be notified to the base station at the same transmission timing. An effect can be obtained.

  (11) In the control information grouping control device according to the present invention, the control information generation unit generates the number of times control information of the number of slots in the time direction of the control information notification unit, and the first control information is By generating the second control information using the propagation path information corresponding to the first slot, and correcting the previously generated control information using the propagation path information corresponding to the second slot And generating the control information by repeating the number of slots in the time direction of the control information notification unit.

  Thus, by generating propagation path information in consideration of more slots, it is possible to improve the estimation accuracy of the propagation path condition.

  (12) In the control information grouping control apparatus according to the present invention, the control information generation unit, as the propagation path information of each of the plurality of slots, propagation path information of a plurality of slots traced back from the timing at which the control information is notified. It is characterized by using.

  Thus, by generating the propagation path information in consideration of a plurality of slots going back in the past, it is possible to improve the estimation accuracy of the propagation path condition.

  (13) One aspect of the wireless device according to the present invention is a control information including the control information grouping device according to any one of claims 1 to 6 and a grouping method selected by the control information grouping device. A control information generation unit for generating the control information, and a transmission unit for transmitting the control information.

  Thus, according to one aspect of the radio apparatus of the present invention, a plurality of slots can be grouped into a two-dimensional array in the frequency direction and the time direction, and propagation path information for each control information notification unit can be transmitted. . Thereby, the amount of control information notified from the mobile station to the base station can be reduced.

  (14) Another aspect of the wireless device according to the present invention includes a receiving unit that receives control information including a grouping method, a propagation path condition for each of one or more slots, and one or more 8. A propagation path estimation unit that outputs propagation path information indicating a propagation path condition for each slot, a grouping method included in the received control information, and propagation path information output by the propagation path estimation unit are input. The control information transmission control unit of the control information notification control device instructs control information generated by the control information notification control device according to claim 12 and the control information generation unit of the control information notification control device. And a transmission unit that transmits at a timing.

  As described above, according to another aspect of the radio apparatus according to the present invention, the propagation path information of the control information notification unit in which a plurality of slots are grouped into a two-dimensional array in the frequency direction and the time direction is generated as control information. can do. Thereby, the amount of control information notified from the mobile station to the base station can be reduced. In addition, it is possible to instruct the timing for transmitting the control information.

  (15) Still another aspect of the radio device according to the present invention is the control information grouping device according to any one of claims 1 to 6, and the propagation path condition for each of one or a plurality of slots. A propagation path estimator that estimates and outputs propagation path information indicating a propagation path situation for each slot or a plurality of slots, a grouping method selected by the control information grouping device, and the propagation path estimator output The control information notification control apparatus according to any one of claims 7 to 12, which receives the propagation path information, and the control information generated by a control information generation unit of the control information notification control apparatus are used as the control information notification control. A transmission unit that transmits at a timing instructed by the control information transmission control unit of the device, and the control information generation unit of the control information notification control device includes a grouping scheme and control information including propagation path information for each control information notification unit And generating a multi-address.

  Thus, according to yet another aspect of the radio apparatus according to the present invention, a plurality of slots can be grouped into a two-dimensional array in the frequency direction and the time direction. Further, propagation path information for each control information notification unit can be transmitted as control information. Thereby, the amount of control information notified from the mobile station to the base station can be reduced. In addition, it is possible to instruct the timing for transmitting the control information.

  (16) In one aspect of the wireless communication system according to the present invention, a slot defined by a certain time length and a certain frequency band is a minimum control information notification unit, and a plurality of two-dimensionally arranged frequency and time directions are arranged. A multi-carrier wireless communication system for controlling a slot control information notification unit between a first wireless device and a second wireless device, wherein the first wireless device is according to any one of claims 1 to 6. A control information grouping device, a control information generating unit that generates, as control information, propagation path information indicating the grouping method selected by the control information grouping device, and data having the control information and the second radio as a transmission destination A second wireless device including a transmission unit that transmits a signal, a receiving unit that receives control information from the first wireless device, a propagation path condition for each of one or a plurality of slots, and one Inputs a channel estimation unit that outputs channel information indicating channel conditions for each of a plurality of slots, a grouping method included in the received control information, and channel information output by the channel estimation unit The control information notification control device according to any one of claims 7 to 12, and the control information generated by the control information generation unit of the control information notification control device, the control information transmission control unit of the control information notification control device The first wireless device based on control information including propagation path information for each control information notification unit notified from the second wireless device. It is characterized by modulating and encoding a data signal destined for the machine.

  Thus, according to the aspect of the wireless communication system according to the present invention, a plurality of slots can be grouped into a two-dimensional array in the frequency direction and the time direction. Thereby, the amount of control information notified from the first wireless device (mobile station) to the second wireless device (base station) can be reduced. Moreover, since the grouping method is selected by the first radio device (base station side), the processing amount of the second radio device (mobile station side) can be suppressed. Further, by grouping a plurality of slots adaptively in the time direction and the frequency direction based on the propagation path fluctuation, it is possible to suppress variations in the propagation path conditions of the slots in the group. Thereby, since an appropriate modulation system can be adopted, the transmission rate can be increased and the communication quality can be improved.

  (17) According to another aspect of the wireless communication system of the present invention, a slot defined by a certain time length and a certain frequency band is used as a minimum control information notification unit, and two-dimensional in the frequency direction and the time direction is used. A multi-carrier wireless communication system for controlling a control information notification unit of a plurality of slots arranged in a first wireless device and a second wireless device, wherein the first wireless device transmits control information including a grouping method. The control information grouping device according to any one of claims 1 to 6, further comprising: a receiving unit that receives data, and a transmitting unit that transmits a data signal whose destination is the second radio device. A channel estimation unit that estimates channel conditions for one or more slots and outputs channel information indicating the channel conditions for one or more slots, and the control information grouping device selects Guru The control information notification control apparatus according to any one of claims 7 to 12, and the propagation path information for each control information notification unit, wherein the transmission information and the propagation path information output by the propagation path estimation unit are input. A transmission unit that transmits control information including the second wireless device based on control information including propagation path information for each control information notification unit notified from the second wireless device. And a data signal having the transmission destination as a transmission destination are modulated and encoded.

  Thus, according to another aspect of the wireless communication system according to the present invention, a plurality of slots can be grouped into a two-dimensional array in the frequency direction and the time direction. Thereby, the amount of control information notified from the first wireless device (mobile station) to the second wireless device (base station) can be reduced. In addition, a plurality of slots are grouped adaptively in the time direction and the frequency direction based on the propagation path fluctuation, thereby suppressing variations in the propagation path conditions of the slots in the group. Thereby, since an appropriate modulation system can be adopted, the transmission rate can be increased and the communication quality can be improved.

  (18) In one aspect of the control information grouping control method according to the present invention, a slot defined by a certain time length and a certain frequency band is set as a minimum control information notification unit, and is two-dimensionally in the frequency direction and the time direction. A control information grouping control method for controlling control information notification units of a plurality of slots arranged, wherein a propagation path fluctuation estimation value is input, and one or more slots in a frequency direction are input based on the propagation path fluctuation estimation value A step of selecting a grouping method for grouping a plurality of slots into a control information notification unit composed of an array of one or more slots in the time direction is provided.

  Thus, according to the aspect of the control information grouping control method according to the present invention, a plurality of slots can be grouped into a two-dimensional array in the frequency direction and the time direction. Thereby, the amount of control information notified from the mobile station to the base station can be reduced. In addition, a plurality of slots are grouped adaptively in the time direction and the frequency direction based on the propagation path fluctuation, thereby suppressing variations in the propagation path conditions of the slots in the group. Thereby, since an appropriate modulation system can be adopted, the transmission rate can be increased and the communication quality can be improved.

  (19) Another aspect of the control information grouping control method according to the present invention is that a slot defined by a certain time length and a certain frequency band is set as a minimum control information notification unit, and the frequency direction and the time direction are two. A control information grouping control method for controlling control information notification units of a plurality of slots arranged in a dimension, and based on propagation path information indicating a propagation path situation, a propagation path fluctuation estimated value indicating a fluctuation in the propagation path situation is obtained. A group for grouping a plurality of slots into a control information notification unit composed of an array of one or more slots in the frequency direction and an array of one or more slots in the time direction, based on the estimation step and the propagation path fluctuation estimation value Selecting a conversion method.

  Thus, according to another aspect of the control information grouping control method of the present invention, a plurality of slots can be grouped into a two-dimensional array in the frequency direction and the time direction. Thereby, the amount of control information notified from the mobile station to the base station can be reduced. Moreover, a propagation path fluctuation estimated value can be estimated based on propagation path information.

  (20) Still another aspect of the control information grouping control method according to the present invention is that a slot defined by a certain time length and a certain frequency band is a minimum control information notification unit, and the frequency direction and the time direction are A control information grouping control method for controlling a control information notification unit of a plurality of slots arranged in two dimensions, and a propagation path variation indicating a propagation path condition variation based on movement speed information indicating a movement speed of a receiver A step of estimating an estimated value, and a plurality of slots are grouped into a control information notification unit composed of an array of one or more slots in the frequency direction and one or more slots in the time direction based on the estimated propagation path fluctuation value Selecting a grouping method to be grouped.

  Thus, according to yet another aspect of the control information grouping control method according to the present invention, the moving speed can be used as the propagation path condition. As a result, even when the moving speed of the mobile station is significant, when the grouping method is selected, it is possible to realize grouping that more appropriately reflects fluctuations in the propagation path condition.

  (21) Another aspect of the control information grouping control method according to the present invention is that a slot defined by a certain time length and a certain frequency band is set as a minimum control information notification unit, and the frequency direction and the time direction are two. A control information grouping control method for controlling control information notification units of a plurality of slots arranged in a dimension, the step of storing control information indicating past propagation path conditions, and the past control information and current propagation path Using the current control information indicating the situation, estimating a propagation path fluctuation estimated value indicating a fluctuation in the propagation path condition, and using the propagation path fluctuation estimated value, one or more slots in the frequency direction and the time direction Selecting a grouping method for grouping a plurality of slots into a control information notification unit composed of an array of one or more slots.

  Thus, according to another aspect of the control information grouping control method according to the present invention, a plurality of slots can be grouped into a two-dimensional array in the frequency direction and the time direction. Thereby, the amount of control information notified from the mobile station to the base station can be reduced. Also, the processing load on the mobile station side can be reduced by selecting the grouping method on the base station side and notifying the mobile station. Further, by grouping a plurality of slots adaptively in the time direction and the frequency direction based on the propagation path fluctuation, it is possible to suppress variations in the propagation path conditions of the slots in the group. Thereby, since an appropriate modulation system can be adopted, the transmission rate can be increased and the communication quality can be improved.

  (22) In the control information grouping control method according to the present invention, the step of selecting the grouping method is characterized in that the number of slots constituting the control information notification unit is made constant.

  Thus, when the number of slots in a group is made constant, the amount of control information in each transmission unit can be made constant by transmitting from the mobile station to the base station. In particular, when the number of slots in a group is fixed and multiple slots are grouped in the time direction, the amount of control information increases as the number of groups in the frequency direction increases, but the control information is divided by elements in the time direction. Then, the amount of control information in each transmission unit can be made constant by transmitting from the mobile station to the base station in a plurality of times. As a result, the control channel can be used to the maximum extent in a communication system in which a control channel with a certain capacity is secured in advance.

  (23) In the control information grouping control method according to the present invention, the step of selecting the grouping method increases the number of slots in the time direction when the propagation path fluctuation estimated value is larger than a predetermined threshold, and the propagation path When the fluctuation estimated value is equal to or less than a predetermined threshold, the number of slots in the frequency direction is increased.

  As described above, an appropriate modulation scheme can be adopted by grouping a plurality of slots adaptively in the time direction and the frequency direction based on the propagation path fluctuation. Thereby, the transmission rate can be increased and the communication quality can be improved.

  According to the present invention, slots arranged two-dimensionally in the frequency direction and the time direction are grouped in the frequency direction and the time direction in accordance with the propagation path conditions, and the propagation path information for each of the grouped slots is obtained. You can be notified. As a result, the amount of control information notified from the mobile station to the base station can be reduced compared to the case of notifying the channel information for each slot.

It is a figure which shows the structural example of the base station of the orthogonal frequency division multiplexing system which concerns on 1st Embodiment. It is a figure which shows the structural example of the mobile station of the orthogonal frequency division multiplexing system which concerns on 1st Embodiment. It is a figure which shows an example of the grouping of the slot in the propagation path where the fluctuation | variation in a frequency direction is moderate, and the fluctuation | variation in a time direction is intense. It is an example of slot grouping in a propagation path where fluctuations in the frequency direction are intense and temporal fluctuations are gentle. It is a figure which shows an example of the control information notification of the uplink in the propagation path condition shown in FIG. FIG. 5 is a diagram illustrating an example of uplink control information notification in the propagation path state illustrated in FIG. 4. It is a figure which shows an example of the grouping system which groups a some slot by the combination of a frequency direction and a time direction. It is a figure which shows an example of the grouping system which groups a some slot when the spreading factor of a frequency direction is 2. FIG. It is a figure which shows the structural example of the base station of the orthogonal frequency division multiplexing system which concerns on 2nd Embodiment. It is a figure which shows the structural example of the mobile station of the orthogonal frequency division multiplexing system which concerns on 2nd Embodiment. It is a figure which shows an example of the system which divides | segments the propagation path information for every control information notification unit, and transmits simultaneously the divided | segmented propagation path information of each of several groups. It is a figure which shows an example of the transmission condition of the propagation path information of 6th Embodiment. It is a figure which shows another example which shows the transmission condition of the propagation path information of 6th Embodiment. It is a figure which shows an example of the transmission condition of the propagation path information of 7th Embodiment. It is a figure which shows another example which shows the transmission condition of the propagation path information of 7th Embodiment. It is a figure which shows an example which shows the transmission condition of the propagation path information of 8th Embodiment. It is a figure which shows the structural example of the base station of the orthogonal frequency division multiplexing system which concerns on 9th Embodiment. It is a figure which shows the structural example of the mobile station of the orthogonal frequency division multiplexing system which concerns on 9th Embodiment. 1 is a diagram illustrating a configuration example of a system disclosed in Patent Document 1. FIG. 1 is a diagram illustrating a configuration example of a system disclosed in Patent Document 2. FIG. 10 is a diagram illustrating a configuration example of a line quality measurement unit disclosed in Patent Document 2. FIG. It is a figure which shows the example grouped in the frequency direction by the propagation path with a large frequency fluctuation of a propagation path, and a small time fluctuation.

Next, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
Base station of OFDM (Orthogonal Frequency Division Multiplex) system that applies adaptive modulation for each slot (subcarrier) or each control information notification unit of slot (subcarrier) according to the first embodiment of the present invention An example of the configuration is shown in FIG. A configuration example of the mobile station is shown in FIG. However, although one base station 100 and one mobile station 200 are shown in FIG. 1 and FIG. 2, a plurality of mobile stations exist, and one mobile station is shown. Further, in this specification, a modulation parameter (MCS: Modulation and channel Coding Scheme) defines at least one of an encoding scheme and a modulation scheme, and an encoding scheme, a modulation scheme, or an encoding scheme and a modulation scheme. Or any combination. One modulation parameter is selected from a plurality of modulation parameters and used.

  In FIG. 1, the data transmission unit of the base station 100 includes an encoding unit 101, a modulation unit 102, a modulation parameter (MCS) control unit 103, an inverse fast Fourier transform (IFFT) unit 104, a control information multiplexing unit. 105 and a wireless transmission unit 106. The data receiving unit of the base station 100 includes a radio receiving unit 107, a control information separating unit 108, a demodulating unit 109, a decoding unit 110, and a control information generating unit 112. In addition to the device, it has a control information storage unit 111 for storing propagation path information.

On the other hand, the mobile station 200 includes a radio reception unit 201, a control information separation unit 202, a propagation path estimation unit 203, an MCS control unit 204 that controls demodulation and decoding methods, a fast Fourier transform (FFT) unit 205, Movement of a general per-subcarrier adaptive modulation OFDM system including a demodulation unit 206, a decoding unit 207, a control information generation unit 212, a control information multiplexing unit 213, an encoding unit 214, a modulation unit 215, and a radio transmission unit 216 In addition to the station apparatus, a propagation path storage unit 208 that stores estimated propagation path information, a propagation path fluctuation estimation unit 209 that estimates fluctuations in the propagation path, and a grouping selection unit 210 that determines a slot grouping method. And a control information transmission control unit 211 that controls the timing of transmitting the control information. In this embodiment, the control information grouping control device is realized by the propagation path storage unit 208, the propagation path fluctuation estimation unit 209, the grouping selection unit 210, the control information transmission control unit 211, and the control information generation unit 212. . The control information grouping control device
At least the grouping selection unit 210 is a component.

  In the present specification, a slot is specified by a time channel defined by a certain time length and a frequency channel defined by a certain frequency band. A slot is a minimum modulation unit having the same modulation parameter, and is a minimum control information notification unit. The frequency channel is composed of one or more subchannels. It is possible that the frequency channel is the same as the subchannel. The control information notification unit is composed of one or more slots, and the adaptive period (adaptive modulation period) is the length in the time direction of the control information notification unit, and is determined by the number of slots in the time direction.

  In the following description, 1 TTI (Transmit Time Interval) · 1 subcarrier is expressed as 1 slot as a minimum unit of a symbol string having the same modulation parameter (modulation method), but a plurality of subcarriers in 1TTI (For example, EUTRA (Evolved UTRA, UTRA: UMTS Terrestrial Radio Access, UMTS: Universal Mobile Tem, etc.) A group of sub-carriers that have the same modulation parameters It is considered as the slot as the minimum unit can be similarly applied to the present invention.

  Further, in this embodiment, an index related to received signal power or carrier power, such as SNR (Signal to Noise Ratio) and SIR (Signal to Interference Ratio), is assumed as propagation path information. An index related to the success or failure of data reception such as (Bit Error Rate) can also be used.

  Hereinafter, the transmission / reception procedure of the base station 100 will be described with reference to FIG. In the transmission unit of base station 100, transmission data is encoded and modulated in encoding unit 101 and modulation unit 102, respectively. At this time, the encoding scheme and the modulation scheme are controlled by the MCS control unit 103 based on channel information (CSI: Channel State Information) notified from the mobile station 200. The control in the MCS control unit will be described later. The modulated symbol sequence is assigned to each subcarrier and IFFT processed in IFFT section 104 to generate an OFDM symbol sequence. In the control information multiplexing unit, a channel estimation symbol sequence (CE) and MCS information (MLI: MCS Level Information) are multiplexed on the OFDM symbol sequence and transmitted through the radio transmission unit 106.

  The signal received by the wireless reception unit 107 is separated into CE, CSI and data symbol sequence for each control information notification unit by the control information separation unit 108. CE is used for propagation path compensation of the received signal, and CSI is sent to the MCS control unit 103. Data symbol sequences are demodulated and decoded by demodulation section 109 and decoding section 110, respectively, and received data is extracted.

  The MCS control unit 103 determines the encoding and modulation scheme (modulation parameter) based on the CSI notified from the mobile station. The MCS control unit 103 can read / write data from / to the control information storage unit 111, and can store CSI when the adaptation period is larger than the minimum adaptation period, and can read it again when switching the modulation parameter. The MCS control unit 103 notifies the selected MCS to the encoding unit 101, the modulation unit 102, and the control information generation unit 112.

  The control information generation unit 112 generates an MLI for sending the MCS notified from the MCS control unit 103 to the mobile station 200 and sends it to the control information multiplexing unit 105.

  Next, the transmission / reception procedure of the mobile station 200 will be described with reference to FIG. A signal received by the wireless reception unit 201 is separated into CE, MLI, and a data symbol sequence by the control information separation unit 202. CE is sent to propagation path estimation section 203, MLI is sent to MCS control section 204 for demodulation and decoding, and the data symbol sequence is sent to FFT section 205. The data symbol sequence is converted into a modulation symbol sequence for each subcarrier in the FFT unit 205, and then demodulated and decoded in the demodulating unit 206 and the decoding unit 207, respectively, and the received data is extracted. At this time, the demodulation method and the decoding method are controlled by the MCS control unit 204 based on the MLI notified from the base station 100 and the grouping method sent from the grouping selection unit 210.

  The propagation path estimation unit 203 estimates the propagation path condition for each subcarrier using CE. The estimated propagation path information (propagation state estimation value) is sent to the propagation path storage unit 208 and the propagation path fluctuation estimation unit 209.

  The propagation path fluctuation estimation unit 209 estimates time fluctuation of the propagation path and / or frequency fluctuation of the propagation path based on the propagation path information transmitted from the propagation path estimation unit 203. At that time, the past propagation path information stored in the propagation path storage unit 208 may be referred to (dotted line arrow from the propagation path storage unit 208 to the propagation path fluctuation estimation unit 209 in FIG. 2). The estimated propagation path fluctuation information (propagation fluctuation estimation value) is sent to the grouping selection unit 210.

  Grouping selection section 210 determines a grouping method for grouping slots based on the propagation path fluctuation information estimated by propagation path fluctuation estimation section 209. When the frequency variation of the propagation path is large and the time variation of the propagation path is small, a grouping method is selected such that the slots are reduced in the subcarrier direction (frequency direction) and more in the time direction. When grouping also in the time direction, the amount of control information to be notified at a time can be suppressed by dividing the control information into a plurality of pieces and notifying the base station at different timings. In addition, since the transmission rate of the control information notified from the mobile station 200 to the base station 100 can be made constant by performing control so as to make the number of slots in the group constant, control with constant communication capacity. In a system that transmits control information used for adaptive modulation using a channel, the control channel can be effectively used.

  Control information transmission control section 211 determines the timing for transmitting the propagation path information of each group to base station 100 based on the grouping method selected by grouping selection section 210. The grouping method and the transmission timing of the propagation path information are notified to the propagation path storage unit 208 and the control information generation unit 212.

  The propagation path storage unit 208 sends the propagation path information to the control information generation unit 212 according to the grouping method and transmission timing notified from the control information transmission control unit 211.

  The control information generation unit 212 notifies the base station 100 of control information (GSI: Grouping Scheme Information) for notifying the base station 100 of the grouping method and the propagation path data transmitted from the propagation path storage unit 208. Propagation path information CSI is generated. The generated propagation path information is sent to the control information multiplexing unit 213 at the timing notified from the control information transmission control unit 211.

  The transmission data is encoded and modulated by the encoding unit 214 and the modulation unit 215, respectively, and the control information transmitted from the control information generation unit 212 is multiplexed by the control information multiplexing unit 213 and transmitted via the radio transmission unit 216. Is done.

  Examples of propagation path variations and subcarrier grouping schemes are shown in FIGS. FIG. 3 shows an example of slot grouping in a propagation path in which fluctuation in the frequency direction is gradual and fluctuation in the time direction is severe. FIG. 3 shows the hatched rectangular portion as one group, but in reality, a plurality of groups of the same size are arranged in the frequency direction, and FIG. 3 shows one of the groups. Is. Here, the grouping is increased in the frequency direction where the propagation path fluctuation is gentle, and is reduced in the time direction where the propagation path fluctuation is severe, thereby suppressing variations in the propagation path conditions of the slots in the group.

  FIG. 4 shows an example of slot grouping in a propagation path where the fluctuation in the frequency direction is large and the fluctuation of the time trend is gentle. FIG. 4 shows the hatched rectangular portion as one group, but actually there are a plurality of groups of the same size in the frequency direction, and FIG. 4 represents one of the groups. Is. Here, the grouping is reduced in the frequency direction where the propagation path fluctuation is severe, and the propagation path fluctuation is increased in the time direction where the propagation path fluctuation is moderate, thereby suppressing variations in the propagation path situation of the slots in the group.

  In addition, for example, when a propagation path variation or a moving speed of the mobile station 200 is estimated and the propagation path variation estimation value or the movement speed estimation value is small, the length of the group in the time direction is preferentially increased. If the control is performed, the grouping method can be determined with a relatively small amount of calculation. As described above, the slots are adaptively grouped according to the propagation state of the propagation path, thereby suppressing variations in the propagation path situation of the slots in the group. By notifying an accurate propagation path condition, it is possible to set a modulation parameter that satisfies the required quality in adaptive modulation, and communication quality is improved.

  An example of uplink control information notification in the propagation path state shown in FIG. 3 is shown in FIG. In FIG. 5, one of the rectangles represents a slot that is a minimum modulation unit and a minimum control information notification unit, and shows three groups A910, B920, and C930 that are long in the frequency direction. Each group shows a group of 6 slots. The control information of each group is shown as control information 911 of group A, control information 921 of group B, and control information 931 of group C. The mobile station 200 estimates the propagation path condition for each subcarrier from the received signal, generates propagation path information from the propagation path conditions of m slots (m = 6 in FIG. 5) in each group, and Notify the base station on the control channel. At this time, the propagation path information for the number of groups is notified in accordance with the downlink adaptation period.

  An example of uplink control information notification in the propagation path state shown in FIG. 4 is shown in FIG. FIG. 6 shows three groups A910, group B920, and group C930 that are long in the time direction, and each group shows six slots grouped together. FIG. 6 shows the control information of each group and each group using the same reference numerals as in FIG. The group in the example shown here is 1 / n in the frequency direction and n times in the time direction compared to the group in the example shown in FIG. 5 (n in FIG. 6 is n). = 3). Since the number of groups in the frequency direction is increased n times by setting the size to 1 / n in the frequency direction, the amount of propagation path information to be notified is increased n times. On the other hand, since the adaptation period is increased by n times by setting the size to n times in the time direction, the notification of control information may take n times. For example, the propagation path situation for each subcarrier is estimated from the received signal, and propagation path information is generated from the propagation path situation of m ÷ n slots in each group. FIG. 6 shows an example in which propagation path information is generated from the first two slots among the grouped six slots.

  For example, it is a figure which shows an example of the grouping system which groups a some slot by the combination of a frequency direction and a time direction. As shown in FIG. 7, a grouping method is selected from four grouping methods for grouping six slots based on propagation path fluctuations in the frequency direction and time domain. FIG. 7A shows the case where the fluctuation in the frequency direction of the propagation path condition is large and the fluctuation in the time direction is small. FIG. 7D shows the fluctuation in the frequency direction of the propagation path condition is small and the fluctuation in the time direction is large. FIG. 7B and FIG. 7C are in the middle of FIG. 7A and FIG. 7D in order. By notifying the entire 1 / n group propagation path information n times within the adaptation period, the amount of propagation path information notification in the example shown in FIG. 5 and the example shown in FIG. . In this way, by making the number of slots in the group constant, the amount of propagation path information notification per time becomes constant, so that the capacity of the uplink control channel can be used efficiently.

  At this time, as a grouping control method performed by the grouping selection unit 210, for example, when the threshold value 1 to the threshold value 3 are set in advance, and the propagation path fluctuation estimated value is smaller than the threshold value 1, FIG. Is applied and the channel fluctuation estimated value is larger than the threshold 1 and smaller than the threshold 2, the grouping of FIG. 7B is applied, and the channel fluctuation estimated value is larger than the threshold 2. When smaller than 3, the grouping of FIG. 7C is applied, and when the propagation path fluctuation estimated value is larger than the threshold 3, the grouping of FIG. 7D is applied. Thereby, it is possible to select a grouping method in accordance with the propagation path fluctuation.

  Furthermore, when the frame is normally received, the threshold value may be increased, and when an error occurs in frame reception, the threshold value may be decreased. Alternatively, if the frame is received normally, the grouping time direction is lengthened and the frequency direction is shortened. If an error occurs in frame reception, the grouping time direction is shortened and the frequency A method of performing control that changes the direction long is also conceivable. Thereby, it is possible to improve the throughput while reducing the deterioration of the error rate.

  Thus, according to this embodiment, the mobile station can group a plurality of slots and notify control information (propagation path information) for each control information notification unit. Thereby, the amount of control information notified from the mobile station to the base station can be reduced. Further, when a plurality of slots are grouped in the time direction, the amount of control information notified at a time can be suppressed by dividing the control information into a plurality of pieces and notifying the base station at different timings. Furthermore, since the amount of propagation path information notification per time is made constant by performing control to make the number of slots in the group constant, the transmission rate of control information notified from the mobile station 200 to the base station 100 is made constant. be able to. This makes it possible to effectively use the control channel in a system that transmits control information used for adaptive modulation using a control channel having a constant communication capacity.

  Further, by grouping slots adaptively in the time direction and the frequency direction according to the propagation state of the propagation path, it is possible to suppress variations in the propagation path conditions of the slots in the group. In addition, by notifying an accurate propagation path condition, it is possible to set a modulation parameter that satisfies the required quality during adaptive modulation, thereby improving communication quality.

  In the present embodiment, the grouping method is changed when the previous adaptation period ends, and at the same time, the same grouping is applied to all subcarriers (slots). Application to a system that applies different grouping for each carrier is also possible.

  Moreover, although this embodiment was demonstrated using the OFDM system, it can be easily applied to the system which transmits the signal spread using the OFDM symbol. By making the number of slots grouped in the frequency direction a multiple of the spreading factor in the frequency direction and not changing the spreading factor within the adaptive period, the propagation path information of the same group in the subcarrier group that selects the same modulation method It is possible to determine the modulation method using.

  For example, when the number of slots in the group is 6, four combinations of frequency direction × time direction can be considered as a grouping method: 1 × 6, 2 × 3, 3 × 2, 6 × 1. FIG. 8 shows an example of a grouping method in which a plurality of slots are grouped by a combination of the frequency direction and the time direction when the spreading factor in the frequency direction is 2. As shown in FIG. 8, when the spreading factor in the frequency direction is 2, the same information can be obtained by spreading by selecting the combination of the frequency direction × time direction of the grouping method from 2 × 3 or 6 × 1. Can be grouped into the same group.

  Further, the present invention can be easily applied to an OFDMA (Orthogonal Frequency Division Multiple Access) system in which different users are assigned to each slot (subcarrier) or control information notification unit (group) of a slot (subcarrier). In this case, the base station can perform transmission data scheduling based on the propagation path information for each control information notification unit (for each group) notified from the mobile station, obtained by the present embodiment.

  In the present embodiment, the case where uplink and downlink have independent links is described, but the present invention can also be applied to TDD (Time Division Duplex) that shares uplink and downlink with slight changes.

  In the above embodiment, the propagation path fluctuation estimation unit 209 estimates the propagation path fluctuation using the propagation path estimation result by the CE, but it is also possible to use its own moving speed. In this case, the propagation path fluctuation estimation unit 209 estimates the propagation path fluctuation using its own moving speed, and outputs the estimated propagation path fluctuation estimated value (propagation fluctuation information). As a result, even when the moving speed of the mobile station is significant, it is possible to appropriately reflect the fluctuation of the propagation path condition when selecting the grouping method.

(Second Embodiment)
In the second embodiment, an aspect of estimating propagation path fluctuations in a base station will be described. Configuration examples of the base station 300 and the mobile station 400 of the present embodiment are shown in FIGS. 9 and 10, respectively. In FIG. 9 and FIG. 10, the component which attached | subjected the same name as FIG. 1, FIG. 2 has the same function. In the present embodiment, the control information grouping control apparatus of the base station 300 is realized by the propagation path fluctuation estimation unit 308, the grouping selection unit 309, and the control information storage unit 313. Further, the control information notification control apparatus of the mobile station 400 is realized by the propagation path storage unit 408, the control information transmission control unit 409, and the control information generation unit 410.

  The base station 300 includes a propagation path fluctuation estimation unit 308 and a grouping selection unit 309 in addition to the configuration of the base station 100 in FIG. The CSI separated by the control information separation unit 310 is sent to the MCS control unit 303 and the propagation path fluctuation estimation unit 308. In addition, the control information storage unit 313 sends past CSI to the propagation path fluctuation estimation unit 308.

  The propagation path fluctuation estimation unit 308 estimates the propagation path fluctuation by comparing the CSI sent from the control information separation unit 310 with the past CSI sent from the control information storage unit 313. The propagation path fluctuation estimated value estimated by the propagation path fluctuation estimation unit 308 is notified to the grouping selection unit 309.

  The grouping selection unit 309 selects a grouping method based on the propagation path fluctuation estimated value notified from the propagation path fluctuation estimation unit 308. As a selection method, the same method as in the first embodiment can be used.

  Based on the grouping method notified from the grouping selection unit 309, the MCS control unit 303 combines the control information notified from the mobile station 400 and controls the MCS. The MCS control unit 303 uses the propagation path information notified from the mobile station 400 to select an MCS for a plurality of grouped slots.

  The control information generation unit 314 generates control information (including GSI and CE) for notifying the mobile station 400 of the grouping method based on the grouping method notified from the grouping selection unit 309. The control information multiplexing unit 305 multiplexes the control information with the transmission data and transmits it via the wireless transmission unit 306.

  The control information separation unit 402 included in the mobile station 400 separates the CE, GSI, and data symbol sequence from the received data, CE is transmitted to the propagation path estimation unit 403, and GSI is transmitted to the control information transmission control unit 409 and the MCS control unit 404, respectively. send.

  The control information transmission control unit 409 controls the transmission timing for transmitting the control information to the base station with reference to the GSI.

  In the system according to the present embodiment, since it is not necessary to estimate propagation path fluctuations in the mobile station 400, the processing load on the mobile station 400 can be reduced. Moreover, since GSI is not transmitted with an uplink signal (uplink frame), the communication efficiency of the uplink signal can be improved.

(Third embodiment)
In the second embodiment, the channel fluctuation estimation unit 308 estimates the channel fluctuation based on the CSI notified from the mobile station by the base station and the stored past CSI. In the present embodiment, a case will be described in which propagation path fluctuations are estimated using the moving speed of a mobile station.

  Instead of estimating the channel fluctuation from the CSI, the channel fluctuation estimating unit 308 estimates the Doppler frequency (the moving speed of the mobile station) based on the uplink signal from the mobile station received by the radio receiving unit 307, and the group Determine the conversion method. At this time, as a method of determining the grouping method, a method using a threshold value and the like can be cited as in the first embodiment.

  Thus, according to this embodiment, the base station can select the grouping method using the moving speed of the mobile station. This eliminates the need for the mobile station to estimate channel fluctuations, thereby reducing the processing load on the mobile station. Moreover, since GSI is not transmitted with an uplink signal, the communication efficiency of the uplink signal can be improved. Even when the moving speed of the mobile station is significant, when the grouping method is selected, it is possible to realize grouping that more appropriately reflects the fluctuation of the propagation path condition.

(Fourth embodiment)
In the first embodiment, the grouping selection unit 210 is provided in the mobile station 200, slot grouping control is performed in the grouping selection unit 210 of the mobile station 200, and the grouping scheme is notified to the base station 100. Instead of the above procedure, a grouping selection unit is placed in the base station 100, and the channel fluctuation value estimated by the channel fluctuation estimation unit 209 of the mobile station is used as channel fluctuation notification control information (CFI: Channel Fluctuation Information). It may be used to notify the base station, and slot grouping control may be performed in the grouping selection unit of the base station. In this case, the base station 100 in FIG. 1 is realized by adding the following functions (components). A grouping selection unit is arranged between the control information separation unit 108 and the MCS control unit 103 in the base station 100. The group selection unit inputs the CFI from the control information separation unit 108, selects a grouping method based on the CFI, and transfers the selected grouping method to the MCS control unit 103 and the control information generation unit 314. Moreover, the mobile station 200 does not need to include a grouping selection unit.

  In the system of the fourth embodiment, since it is not necessary to perform a process for determining a grouping method in the mobile station, the processing burden on the mobile station can be reduced.

(Fifth embodiment)
In the first embodiment, as shown in FIG. 6, when the propagation path information is notified from the mobile station 200 to the base station 100 a plurality of times within the adaptive period, the propagation path information of different groups is notified each time. In the present embodiment, a mode is described in which the propagation path information for each control information notification unit is divided into a plurality of pieces, and the propagation path information divided into a plurality of groups is transmitted at the same time of transmission. FIG. 11 is a diagram illustrating an example of a method of dividing the propagation path information for each control information notification unit and simultaneously transmitting the divided propagation path information of each of a plurality of groups. FIG. 11 shows each group and the control information of each group using the same reference numerals as in FIG.

  As shown in FIG. 11 as an example, the propagation path information of each group is divided into the number of times the mobile station notifies the base station within the adaptation period, and the propagation path information of all the groups is transmitted multiple times. Transmit over the transmission timing. FIG. 11 illustrates an example in which the propagation path information of each group is generated from the first two slots in the time direction of each group.

  In the present embodiment, since the propagation path information of all groups is notified to the base station at the same transmission timing, the same time diversity effect can be obtained in all groups when the uplink propagation path information is notified.

(Sixth embodiment)
In the first or fifth embodiment, as shown in FIG. 6 or FIG. 11, when generating the propagation path information for each control information notification unit, the propagation path in the propagation path situation in the first slot of the adaptive period Only situation estimates were considered. In this embodiment, as shown in FIG. 12 or FIG. 13, the propagation path information is generated using all the propagation path state estimated values in the slots from the first slot of the adaptive period to the time when the propagation path information is transmitted. To do. FIG. 12 is a diagram illustrating an example of a transmission state of propagation path information according to the present embodiment. FIG. 13 is a diagram illustrating another example of a transmission state of propagation path information according to the present embodiment. 12 and 13 show each group and the control information of each group using the same reference numerals as in FIG.

  For example, as shown in FIG. 6 or FIG. 11, when three slots in the time direction and two slots in the frequency direction are grouped, the base station is notified in three steps. At this time, in the first embodiment, the propagation path information of the group is generated from the propagation path state estimation values in the first two slots of the adaptation period and transmitted to the base station. On the other hand, in the present embodiment, as shown in FIG. 12, the channel information based on the channel state estimation value in the first two slots is notified at the first transmission, and the first two slots at the second transmission. And the propagation path information generated based on the estimated propagation path conditions in 4 slots of the next 2 slots, and propagation based on the estimated propagation path conditions in all slots in the group at the third transmission. Notify the route information. For example, the control information generation unit 212 generates propagation path information by averaging the propagation path state estimation values in all slots in the group by the number of slots.

  Alternatively, as shown in FIG. 13, at the time of the first transmission, propagation path information based on the propagation path state estimated value in the first two slots is created, and 1 of the propagation path information divided into three. Send one. At this time, for each group, one of the propagation path information divided into three is transmitted. At the time of the second transmission, control information that corrects the propagation path information generated at the first transmission by combining with a part of the propagation path information transmitted the first time from the propagation path state estimation values in the four slots, Send to base station. At the time of the third transmission, control information that further corrects the propagation path information transmitted until the second time from the propagation path state estimation values in the six slots is generated and transmitted to the base station. For example, when the propagation path information is quantized, the higher bits are sequentially transmitted, and after the second feedback, the value indicated by the bit string combined with the already transmitted control information bits is the propagation path for the second and subsequent feedbacks. A bit string that is close to the estimated value is transmitted.

  12 and 13, the control information generation unit 212 uses the channel state estimation value newly estimated by the channel estimation unit 203 and the past channel state estimation value stored in the channel storage unit 208. Generate control information.

  Thus, in this embodiment, the propagation path state estimation accuracy can be improved by generating propagation path information in consideration of many slots.

(Seventh embodiment)
In the first embodiment or the fifth embodiment, as shown in FIG. 6 or FIG. 11, when generating the propagation path information for each control information notification unit, only the propagation path condition in the first slot of the adaptation period is considered. did. In the present embodiment, as shown in FIG. 14 or FIG. 15, the propagation path information is generated using all or a part of the slots from the slot of the past adaptive period to the time of transmitting the propagation path information. FIG. 14 is a diagram illustrating an example of a transmission state of propagation path information according to the present embodiment. FIG. 15 is a diagram illustrating another example of a transmission state of propagation path information according to the present embodiment. 14 and 15, the same reference numerals as those in FIG. 5 are used to indicate each group and the control information of each group.

  For example, as in the example illustrated in FIG. 14, the control information generation unit 212 uses the propagation path state estimation values in a total of 6 slots from the slot retroactive to 2 slots from the propagation path information notification time to the notification slot. Generate group propagation path conditions. Or, as shown in FIG. 15, the control information generation unit 212, based on the propagation path state estimation values in the six slots including the first two slots and the four slots in the past adaptive period at the first transmission. The propagation path information is created, and one of the three pieces of propagation path information is transmitted. At the time of the second transmission, the control information generation unit 212 performs the initial transmission by combining a part of the propagation path information transmitted first from the propagation path environment estimated values in 6 slots including 4 slots in the past adaptive period. Control information that corrects the generated propagation path information is generated and transmitted to the base station. The control information generation unit 212 generates control information that further corrects the propagation path information transmitted until the second time from the propagation path state estimation values of 6 slots at the third transmission, and transmits the control information to the base station.

  Thus, in this embodiment, the propagation path state estimation accuracy can be improved by generating propagation path information in consideration of many slots.

(Eighth embodiment)
In the sixth embodiment or the seventh embodiment, when notifying the propagation path information from the mobile station to the base station multiple times within the adaptive period, the propagation path environment in the slot received before the propagation path information notification time Control information to be notified was generated.

  In this embodiment, whether to consider the propagation path environment in the slot received before the propagation path information notification is determined based on the delay time after receiving the slot before the propagation path information notification. FIG. 16 is a diagram illustrating another example of a transmission state of propagation path information according to the present embodiment. Also in FIG. 16, the same reference numerals as in FIG. 5 are used to indicate each group and the control information of each group. For example, as in the example illustrated in FIG. 16, if the time during which no signal is received from the base station is greater than a certain value, the control information generation unit 212 does not consider the previous slot.

  As described above, in the present embodiment, it is possible to reduce the influence of the time variation of the propagation path on the propagation path state estimated value for each control information notification unit.

(Ninth embodiment)
In the first to eighth embodiments, assuming the information indicating the SNR or the like as the propagation path information notified from the mobile station to the base station, the MCS is determined in the base station. In this embodiment, the mobile station determines the MCS for each control information notification unit (for each group), and notifies the base station of information related to the transmission rate such as MCS as propagation path information using the uplink control channel. explain.

  In the present embodiment, a case will be described in which the mobile station determines the MCS for each control information notification unit and notifies the base station using the uplink control channel. Configuration examples of the base station and the mobile station of this embodiment are shown in FIGS. 17 and 18, respectively. Components having the same names as those in FIGS. 1 and 2 have similar functions. Below, the procedure of this embodiment is demonstrated according to FIG. 17 and FIG.

  The mobile station 600 in this embodiment includes an MCS determination unit 612 in addition to the blocks of the mobile station 200 in the first embodiment shown in FIG. In mobile station 600, CE is separated in control information separation section 602 from the signal received by radio reception section 601, and the separated CE is sent to propagation path estimation section 603.

  The propagation path estimation unit 603 estimates the propagation path condition for each subcarrier based on the CE. The propagation path condition estimation result (propagation path estimated value) is notified to the propagation path storage unit 608 and the propagation path fluctuation estimation unit 609.

  The propagation path fluctuation estimation unit 609 estimates the propagation path fluctuation from the estimation result of the propagation path situation. At this time, a past propagation path state estimated value stored in the propagation path storage unit 608 may be referred to. The propagation path fluctuation estimated value is notified to the grouping selection unit 610. Grouping selection section 610 determines a slot grouping method based on the propagation path fluctuation estimated value. The control information transmission control unit 611 controls the timing for transmitting control information. Based on the transmission timing notified from the control information transmission control unit 611, the propagation path storage unit 608 sends the propagation path state estimation value for each subcarrier to the MCS determination unit.

  The MCS determination unit 612 determines the MCS for each subcarrier based on the result of the low number of channel conditions for each subcarrier sent from the channel storage unit 608 and notifies the control information generation unit 613 of the MCS. The control information generation unit 613 generates control information GSI for notifying the grouping method and control information MLI for MCS notification, and sends them to the control information multiplexing unit 614. The control information multiplexing unit 614 multiplexes the control information generated by the control information generation unit 613 into a transmission data sequence, and transmits the transmission data sequence via the wireless transmission unit 617.

  In base station 500, control information is separated in control information separation section 508 from the signal received by radio reception section 507, and the separated control information is sent to MCS control section 503. The MCS control unit 503 controls the MCS at the time of encoding and modulation based on MLI and GSI that are control information.

  Thus, in this embodiment, since it is not necessary to multiplex the control information for MCS notification on the downlink signal, it is possible to improve downlink transmission efficiency. Also, since the amount of information required for MCS notification is generally smaller than the amount of information required for channel information notification, uplink communication efficiency can also be improved. On the base station side, modulation and coding can be performed using modulation parameters desired by the mobile station.

  In each of the first to eighth embodiments, the propagation path information may be information on the transmission rate such as MCS described in this embodiment, instead of the information indicating the SNR. The propagation path fluctuation estimation unit estimates the propagation path fluctuation based on the propagation path information related to the transmission rate and outputs a propagation path fluctuation estimated value. Also, when estimating the propagation path information in the mobile station, the propagation path estimation unit can estimate the information on the transmission rate as the propagation path status estimation value as the propagation path information using the CE.

  As described above, according to a preferred embodiment of the present invention, control for transmission / reception between two wireless devices that perform wireless communication (described in the above embodiments using a base station and a mobile station). The amount of information can be reduced. In other words, the mobile station notifies the base station of the propagation path information for each control information notification unit (for each group) in which a plurality of slots are grouped, so that the propagation path information for each slot (for each subcarrier) is notified. Compared to the case, the amount of control information to be notified can be greatly reduced.

  Further, according to the preferred embodiment of the present invention, the transmission rate of the control information amount notified from the mobile station to the base station can be made constant. That is, when the number of slots in a group is fixed and a plurality of slots are grouped in the time direction, the control information is divided into a plurality of times and transmitted from the mobile station to the base station. The amount of control information can be made constant. As a result, the control channel can be used to the maximum extent in a communication system in which a control channel with a certain capacity is secured in advance.

  Furthermore, according to a preferred embodiment of the present invention, transmission quality can be improved. In other words, by selecting the grouping method according to the time variation and frequency variation of fading, it is possible to notify the base station of propagation path information with less error compared to the conventional grouping, so adopt an appropriate modulation method Can do. Thereby, communication quality can be improved.

  In each of the above-described embodiments, the aspect in which the propagation path fluctuation estimation unit and the grouping selection unit are provided in either the base station or the mobile station as components of the control information grouping control apparatus has been described. However, it does not exclude that both the base station and the mobile station are provided. In addition, each component of the control information grouping control device provided in the base station or mobile station is not limited to that described in the above embodiments. It suffices to have a function of grouping at least slots that are the minimum modulation unit and the minimum control information notification unit, and can be realized by the grouping selection unit. Further, the control information notification control device has a function of generating control information including at least propagation path information, and a function of instructing a timing for notifying propagation path information for each control information notification unit in which a plurality of slots are grouped. It can be realized by the control information generation unit and the control information transmission control unit.

  In each of the above embodiments, the control information notified from the mobile station to the base station includes at least propagation path information for each control information notification unit, and may further include a grouping method.

100, 300, 500 Base station 101, 301, 501 Encoding unit 102, 302, 502 Modulation unit 103, 303, 503 MCS control unit 104, 304, 504 IFFT unit 105, 305, 505 Control information multiplexing unit 106, 306, 506 Radio transmission unit 107, 307, 507 Radio reception unit 108, 310, 508 Control information separation unit 109, 311, 509 Demodulation unit 110, 312, 510 Decoding unit 111, 313, 511 Control information storage unit 112, 314, 512 Control information generation unit 200, 400, 600 Mobile station 201, 401, 601 Radio reception unit 202, 402, 602 Control information separation unit 203, 403, 603 Propagation path estimation unit 204, 404, 607 MCS control unit 205, 405, 604 FFT unit 206, 406, 605 Demodulation unit 207, 407, 606 Decoding unit 208, 408, 608 Propagation path storage unit 209, 308, 609 Propagation path fluctuation estimation unit 210, 309, 610 Grouping selection unit 211, 409, 611 Control information transmission control unit 212, 410, 613 Control information generation unit 213, 411, 614 Control information multiplexing unit 214, 412, 615 Encoding unit 215, 413, 616 Modulation unit 216, 414, 617 Radio transmission unit 910 Group A
920 Group B
930 Group C
911 Group A control information 921 Group B control information 931 Group C control information

Claims (14)

A communication system in which a base station and a mobile station communicate with each other,
The base station
A transmitter for transmitting a signal including a propagation path estimation symbol to the mobile station;
Receiving a signal including propagation path information transmitted from the mobile station,
The mobile station receives a signal transmitted from the base station;
A propagation path estimation unit that estimates a propagation path condition using a propagation path estimation symbol included in the received signal and calculates a propagation path condition estimated value;
A transmission unit that transmits a signal including propagation path information representing the propagation path state estimated value,
In the communication system, the mobile station transmits, at different timings, propagation path information corresponding to each of a plurality of frequency bands divided in a frequency direction in the transmission unit.   The communication system according to claim 1, wherein the propagation path information is transmitted through a specific control channel.   The communication system according to claim 2, wherein the control channel has a constant capacity.   2. The communication system according to claim 1, wherein the number of propagation path information transmitted in a certain time length is one. A mobile station that transmits propagation path information representing a propagation path state estimation value estimated using a signal transmitted from a base station to the base station,
A mobile station characterized by transmitting propagation path information corresponding to each of frequency bands divided into a plurality in frequency direction at different timings.   The mobile station according to claim 5, wherein the propagation path information is transmitted through a specific control channel.   The mobile station according to claim 6, wherein the control channel has a constant capacity.   6. The mobile station according to claim 5, wherein the number of propagation path information transmitted in a certain time length is one. A base station that receives a signal including propagation path information representing a propagation path state estimation value estimated by a mobile station using a signal transmitted from the base station,
A base station that receives propagation path information corresponding to each of a plurality of frequency bands divided in the frequency direction and transmitted from the mobile station at different timings. A transmission control method for transmitting to the base station propagation path information representing a propagation path state estimation value estimated using a signal transmitted from a base station,
A transmission control method characterized by transmitting propagation path information corresponding to each of a plurality of frequency bands divided in a frequency direction at different timings.   The transmission control method according to claim 10, wherein the propagation path information is transmitted through a specific control channel.   12. The transmission control method according to claim 11, wherein the control channel has a constant capacity.   13. The transmission control method according to claim 12, wherein the number of propagation path information transmitted in a fixed time length is one. A signal processing method for receiving a signal including propagation path information representing a propagation path state estimation value estimated by a mobile station using a signal transmitted from a base station,
A signal processing method comprising receiving propagation path information corresponding to each of a plurality of frequency bands divided in the frequency direction and transmitted from the mobile station at different timings.

Images