JP5367873B2 - CQI notification method, radio resource allocation method, and base station apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently implement effect of a frequency scheduling while reducing the number of bits of CQI information of which a user terminal notifies a base station. <P>SOLUTION: A method for CQI notification from a user terminal to a base station comprises steps in which: the user terminal notifies the base station of a CQI average value of the whole reception band in a constant period during a notification opportunity given by the base station; the user terminal notifies the base station of a resource block whose value is beyond the CQI average value by equal to or larger than an m-th level (1&le;m&le;n) in an m-th notification opportunity (1&le;m&le;n), where there are n notification opportunities in a notification period corresponding to the CQI average value; and the base station retains the notified CQI average value, while reducing the retained CQI average value in response to elapsed time from the notification. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a radio communication control technique, and in particular, control of the number of bits of CQI information notified from a user terminal to a base station, allocation of radio resources based on this, and the relationship between the base station and the user terminal for realizing them Concerning configuration.

  In the downlink shared data channel, when applying frequency scheduling considering reception channel quality (CQI), CQI information notified from the user terminal to the base station is used. In HSDPA (High Speed Downlink Packet Access) standardized by 3GPP, a dedicated physical control channel is used for CQI notification.

  Currently, LTE (Long Term Evolution) is being standardized as mobile communication with higher speed and larger capacity than HSDPA. In the LTE network configuration (evolved UTRAN), a shared control channel is used for CQI notification in the uplink.

  In this case, the uplink radio resource allocation control for CQI feedback is essential on the base station side. In order to efficiently use radio resources and increase system throughput, it is necessary to sufficiently obtain the effect of frequency scheduling while reducing the number of bits of CQI information reported in the uplink as much as possible.

  As a method of reducing the number of bits by uplink CQI feedback, a method of expressing a measurement result of a pilot channel in each resource block by a 0/1 bit sequence has been proposed (for example, see Non-Patent Document 1). In this method, when the measurement result (CQI) for each resource block (RB) is notified to the base station, first, the average value of all the resource blocks is notified, and bit “1” is set to the resource block that reaches the average value. Bits “0” are mapped to other resource blocks and notified. The base station recognizes that the RB mapped with “1” has the CQI average value as reported, and that the RB mapped with “0” has a value several dB (xdB) lower than the average value. Recognize and schedule.

  In this document, in order to further reduce the number of notification bits, at a certain time t = 0, the CQI value of every other (for example, even numbered) resource block is reported as 0 or 1, and the next time t = 1, the CQI value of a resource block that has not been reported previously (for example, an odd number) is reported as 0 or 1. For resource blocks not reported by the base station, time interpolation is performed using the CQI value reported previously.

Motorola, R1-060018, "Performance Evaluation of EUTAN Downlink CQI Feedback Schemes", 3GPP TSG RAN1 # 44, Helsinki, Finland, January 23-25, 2006

  In the present invention, when performing frequency scheduling (multiuser scheduling) on a downlink shared channel, the control bits of CQI information notified from the user terminal to the base station are reduced as much as possible, and the effect of frequency scheduling is sufficiently obtained. It is an object of the present invention to provide a CQI notification method that enables the above.

  It is another object of the present invention to provide an uplink radio resource allocation method for CQI notification.

  It is another object of the present invention to provide a base station configuration and a user terminal configuration for realizing the above CQI notification method and radio resource allocation method.

As a first aspect of the present invention, a CQI notification method from a user terminal to a base station includes:
(A) At the CQI notification opportunity assigned by the base station, report the CQI information of the top N resource blocks with good reception channel quality and the resource block numbers to the base station;
(B) When the resource blocks that have already reported CQI information in the past K notification opportunities are included in the top N resource blocks, or the resources that have already reported CQI information in the past K notification opportunities If the current CQI is not improved from the CQI at the time of reporting by a block and the amount of improvement determined in advance, the resource block is excluded, and then CQI information of a resource block with good reception channel quality The resource block number is reported to the base station.

  In a preferred embodiment, the user terminal receives a control signal for reporting the values of N and K from the base station, and according to the notified values of N and K, CQI information of the top N resource blocks And notify the base station.

  The values of N and K notified from the base station are notified to the user terminal by higher layer, for example, layer 3 signaling.

In the second aspect, the CQI notification method from the user terminal to the base station is:
(A) In a notification opportunity given from the base station, the CQI average value of the entire reception band is notified from the user terminal to the base station at a fixed period,
(B) Assuming that there are n notification opportunities during the notification cycle of the CQI average value, the CQI average value is set to the mth (1 ≦ m ≦ n) in the m-th notification opportunity (1 ≦ m ≦ n). The base station is notified of a resource block exceeding the level of).

  In a preferred embodiment, the correspondence relationship between the notification opportunity and the level exceeding the CQI average value is notified in advance from the base station to the user terminal, and the user terminal performs the first and first according to the notified correspondence relationship. At each of the two notification opportunities, the resource block number exceeding the first level by the CQI average value and the resource block number exceeding the second level are notified.

  As an example, in each of the first and second notification opportunities, a base station uses, as CQI information, a bit string obtained by mapping a resource block exceeding the first or second level and other resource blocks with a binary code. Notify

In a third aspect, a method for allocating uplink radio resources for CQI feedback to user terminals is provided. This uplink radio resource allocation method is:
(A) Notifying the user terminal of an allocation period of CQI feedback radio resources for notifying the base station of CQI information and allocated radio resources;
(B) receiving and holding CQI information notified from the user terminal using the radio resource at the allocation period in the base station;
(C) Based on at least the CQI information and the moving speed of the user terminal, at least one of the allocation period of the CQI feedback radio resource and the amount of radio resource to be allocated is changed.

In a good example,
(D) It further includes the step of notifying the user terminal of the allocation cycle, the allocated radio resource, and the change result from the base station through higher layer signaling.

In the fourth aspect, a base station apparatus is provided. Base station equipment
(A) a CQI information reproduction holding unit for reproducing CQI information notified from the user terminal and holding the information for each resource block;
(B) a CQI notification parameter determination unit that determines a CQI notification parameter serving as an index when the user terminal notifies the CQI information based on the CQI information;
Have
The CQI information reproduction holding unit resets the held CQI information when a certain valid period has elapsed from the notification, based on the current CQI notification parameter determined by the CQI notification parameter determination unit.

  In a preferred example, the CQI notification parameter determination unit determines the CQI notification parameter based on at least the CQI information notified from the user terminal and the moving speed of the user terminal.

  In another preferred example, the base station apparatus further includes an upper layer control signal generation unit that generates an upper layer control signal that notifies the CQI notification parameter.

In the fifth aspect, a user terminal is provided. User terminal
(A) a CQI estimator that estimates downlink reception quality for each resource block in the received signal band;
(B) a reception unit that receives an upper layer control signal including an uplink radio resource allocation period for notifying the base station of CQI information, an allocated radio resource, and a notification parameter for notification;
(C) a CQI information generation unit that generates the CQI information from the CQI estimation result based on the notification parameter;
(D) a transmission unit configured to transmit the generated CQI information to the base station using the allocated radio resource in the radio resource allocation cycle.

  In a preferred embodiment, the CQI information generating unit generates the CQI information including CQI information of the top N resource blocks with good CQI estimation and the resource block numbers based on the notification parameter.

  In another preferred embodiment, the CQI information generator generates a resource block having a CQI higher than a first level from a CQI average of the entire band of the received signal in a first notification opportunity based on the notification parameter. A signal to be notified is generated, and a signal to notify a resource block having a CQI exceeding the second level from the CQI average is generated at a second notification opportunity.

At least one of the CQI notification method, the radio resource allocation method, the base station configuration, and the user terminal configuration described above can reduce the number of bits of CQI information and appropriately allocate radio resources for CQI feedback. .
As a result, effective use of radio resources and an increase in system throughput are realized.

It is the schematic which shows the CQI measurement / notification method 1 of embodiment of this invention. In the CQI notification method of FIG. 1, it is the schematic which shows the example which decreases the CQI information hold | maintained in a base station with progress of the time from reception. It is the schematic which shows the CQI measurement / notification method 2 of embodiment of this invention. It is the schematic which shows the example of radio | wireless allocation of the uplink for CQI feedback with respect to a user terminal. It is a schematic block diagram which shows the base station structure of embodiment of this invention. It is a schematic block diagram which shows the structure of the user terminal of embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a first example of a CQI measurement / notification method according to an embodiment of the present invention. The base station (node B) reports the CQI notification opportunity cycle and uplink radio resources used for CQI notification (feedback) for each user terminal (UE), for example, by higher layer (L3) signaling. Details of the CQI notification cycle and the uplink radio resource allocation method for CQI feedback will be described later.

  In the example of FIG. 1, notification opportunities n, n + 1, n + 2,... Are given to this user terminal (UE). The UE notifies the average value of the CQI over the entire received signal band at regular intervals within the given notification opportunity. For example, at the notification opportunity n, the average CQI is notified to the base station (node B). Thereafter, the individual CQI information of the resource block is notified to the base station at every given notification opportunity until the next average value is notified. The CQI information may be an absolute value of the measured CQI, or may be a difference between the latest CQI average value and the measured CQI value as in the example of FIG.

  In FIG. 1, only the resource block (RB) having the highest CQI value is reported as an example in which a difference from the average value is reported. As a method of reducing the number of bits of CQI information, there are a method of extending a reporting period (lowering a reporting frequency) and a method of reporting only those having a relatively good CQI rather than reporting all resource blocks. However, in FIG. 1, the latter method is adopted. The base station variably determines how many upper resource blocks the CQI value is reported to. In FIG. 1, the fact that CQI information is reported only for the highest RB is such that the uplink radio resource provided for CQI feedback corresponds to the CQI report for one resource block. Means that. Therefore, as described later, in the base station, more CQI feedback is required for scheduling, and when the amount of CQI feedback radio resources allocated to a specific UE is increased, the UE For example, the CQI information of the upper two resource blocks is notified.

  After sending the band average CQI, the UE again measures the CQI value for each of the eight resource blocks # 0 to # 7 allocated in the downlink at the notification opportunity n + 1. In the notification opportunity n + 1, the CQI of the resource block # 2 is the highest, and so on, followed by the resource blocks # 4, # 3, # 1,. Therefore, the UE notifies the base station of the difference between the measured CQI value and the latest average value as the CQI information of the resource block # 2 together with the resource block number.

  The base station recognizes that all resource blocks # 0 to # 7 have an average value by reporting the average value at the notification opportunity n, but the CQI information of the resource block # 2 at the notification opportunity n + 1 For resource block # 2, the actual CQI value (average value plus difference) is recognized.

  At the notification opportunity n + 2, the CQI value of the resource block # 6 is the highest as a measurement result in the UE. Therefore, the UE notifies the base station of the difference between the CQI value of the resource block # 6 and the average value together with the resource block number. . The base station adds the reported value to the average value, and recognizes the CQI value in resource block # 6.

  Also in the notification opportunity n + 3, the RB number and the CQI information are notified about the resource block # 1 in which the highest CQI value is measured.

  Since the base station holds the reported CQI information for a certain period, the CQI information is sequentially accumulated. On the other hand, the average value is reset in order from the old CQI value after a certain period. In the example of FIG. 1, the period during which the CQI report is held in the base station (referred to as the CQI validity period) is set as four notification opportunities. That is, the CQI after four notification cycles from the notification is reset to the average value, but the reported value is held until then.

  In the notification opportunity n + 4, the CQI value measured by the UE is the highest in the resource block # 6, but the CQI value of the RB # 6 has already been reported in the past four notification opportunities within the CQI validity period or the reset period. Has been. In this case, the UE notifies the base station of the resource block number and CQI information for the resource block # 7 having the second highest CQI value.

  At the notification opportunity n + 5, the CQI value of the resource block # 4 is the best, and the resource block number and CQI information are notified to the base station. In the base station, the CQI information for the resource block # 2 sent to the notification opportunity n + 1 is reset and returned to the average value.

  In the notification opportunity n + 6, the CQI information and resource block number of the resource block # 5 are notified, and the base station resets the CQI value of the resource block # 6 reported in the notification opportunity n + 2 to the average value.

  As described above, in the CQI notification method shown in FIG. 1, the base station uses the upper layer (L3) for the CQI notification opportunity cycle and the feedback uplink radio resource used for CQI notification for each user terminal (UE). ) Signaling.

Each user terminal notifies the average CQI of the entire received signal band at a specific notification opportunity (at a fixed period) among the designated CQI notification opportunities. In other notification opportunities, CQIs and RB numbers of the top N resource blocks (RBs) with good reception channel quality are notified. However, from the top N, resource blocks that have already been reported in the past K notification opportunities that are CQI valid periods (reset cycles), or CQI has already been reported in the past K notification opportunities, and the past The resource block whose current CQI is not improved from the CQI at the time of reporting is improved beyond a predetermined improvement amount.
The values of N and K in this case are determined by the base station and notified to each user terminal by higher layer (L3) signaling.

  In the base station, the CQI information transmitted from the user terminal is stored in a memory, and scheduling is performed based on the stored CQI information. The CQI information stored in the memory is reset when a certain valid period (K notification opportunities) elapses. The reset value may be a CQI value of the latest band average or a predetermined value.

  FIG. 2 is a modified example of the operation at the base station of the CQI notification method 1 of FIG. The CQI information used for scheduling at the base station may be decreased in value according to the elapsed time stored in the memory. This is because the reliability of the CQI information deteriorates with time.

  For example, at the notification opportunity n + 1, the CQI information of the resource block # 2 is notified from the user terminal (UE) and stored in the memory of the base station. At notification opportunity n + 2, CQI information of resource block # 6 is notified and stored in the memory of the base station. At this time, the CQI value of resource block # 2 notified previously is decreased by a predetermined amount. At the notification opportunity n + 3, the CQI value of the resource block # 1 is notified from the user terminal. Each of the CQI values of resource blocks # 2 and # 6 stored in the base station memory is decreased by a predetermined amount. The CQI value stored in the memory is reduced as time elapses from the notification, but is reset to the average value of the latest band, for example, when the valid period of the CQI elapses.

  The method of FIG. 2 interpolates the reliability of CQI information that decreases with the passage of time, so that more appropriate scheduling is possible.

  FIG. 3 is a diagram for explaining a CQI measurement / notification method 2 according to an embodiment of the present invention. In the CQI notification method of FIG. 3, each user terminal assigns a resource block number greater than a predetermined value (good CQI) to the base station compared to the average CQI of the received signal band at a certain notification opportunity. Notice. The predetermined value compared to the average value is different for each notification opportunity, and the base station determines whether or not the notification opportunity is higher than the average value in the upper layer (L3). Notify the user terminal by signaling.

  In FIG. 3, as in FIG. 1, for each user terminal (UE), the base station determines the period of CQI notification opportunities and the uplink radio resources for feedback used for CQI notification in the upper layer (L3). Notify by signaling.

  In the notification opportunity n (specified notification opportunity), each user terminal notifies the average CQI of the entire received signal band. In the example of FIG. 3, it is assumed that resource blocks (RB) # 0 to # 7 are given as in FIG.

  In the notification opportunity n + 1, the user terminal notifies the number of the resource block having a CQI larger by 2 dB or more than the band average reported in the notification opportunity n according to the signaling information from the base station. In this example, RB # 0, # 4, # 4, # 5, and # 7 exceed the band average by 2 dB or more. Therefore, the bits corresponding to these resource blocks are mapped to “1”, the bits corresponding to other resource blocks are mapped to “0”, and a bit string “10101101” is transmitted.

  Here, since the base station presets that the resource block number reported at the notification opportunity n + 1 is a resource block exceeding the average value by 2 dB or more, the CQI value of those resource blocks stored in the memory is set. Increase by 2 dB.

  In the notification opportunity n + 2, the user terminal notifies a resource block whose CQI value is 4 dB or more larger than the band average reported in the notification opportunity n. Here, since RB # 2 and # 5 exceed the band average by 4 dB or more, the bits corresponding to these resource blocks are mapped to “1”, and the bits corresponding to other resource blocks are mapped to “0”. Then, the bit string “00100100” is transmitted to the base station as CQI information. Since the base station presets that the resource block that exceeds the average by 4 dB or more is reported at the notification opportunity n + 2, the base station updates the CQI values of RB # 2 and # 5 stored in the memory.

  In the notification opportunity n + 3, the user terminal notifies a resource block having a CQI larger by 6 dB or more than the band average reported in the notification opportunity n. Here, since only RB # 0 is applicable, the bit string “10000000” is transmitted to the base station. The base station updates the CQI value of RB # 0 stored in the memory.

  As described above, in the CQI notification method 2 in FIG. 3, the notification opportunity and the value exceeding the predetermined band average (how many dB have been exceeded) are associated with each other and notified from the base station to each user terminal. In accordance with the correspondence relationship, the resource block number that satisfies the condition given there is notified for each notification opportunity. That is, assuming that there are n notification opportunities between the current CQI average notification and the next CQI average notification, the mth (1 ≦ m ≦ n) notification opportunity is the CQI average. Resource blocks that exceed the mth level (1 ≦ m ≦ n) or higher are selectively notified. This method requires a small amount of information required for CQI notification.

  Note that the method of FIG. 2 may be incorporated into the method of FIG. That is, the CQI value held in the memory of the base station may be reduced according to the elapsed time from the notification to compensate for the decrease in reliability over time.

  FIG. 4 is a diagram illustrating a method for allocating uplink radio resources for CQI feedback by a base station.

  The base station allocates uplink radio resources to each user terminal in a predetermined pattern for CQI notification from the user terminal. The allocation pattern is changed according to the moving speed of each user terminal, the reception channel quality, and the total number of users. The change of the allocation pattern includes both the change of the allocated resource amount and the change of the allocation cycle (notification opportunity). The resource amount to be allocated is variably set in both the frequency direction and the time direction.

  For example, for a user terminal with a fast moving speed, the radio resource allocation period (notification interval) for CQI feedback is shortened so that downlink scheduling can follow the movement of the user terminal. For user terminals with little movement, the radio resource allocation period for CQI feedback is set relatively long to reduce the total number of bits required for CQI notification.

  In the example of FIG. 4, at present, a radio resource is given to a certain user terminal (UE) at an allocation cycle T1 (for example, every 10 subframes). The radio resource allocated here is, for example, a resource having one subcarrier length in the frequency direction and one subframe length in the time direction. The user terminal uses the given radio resource for CQI feedback, for example, the CQI of the upper one resource block (example in FIG. 1), or the resource block number (example in FIG. 3) higher than a predetermined level from the band average. Notice.

  For example, assume that the CQI feedback has been performed in the allocation cycle T1 for a while. For example, it is assumed that the moving speed of the user terminal has decreased. Then, the base station expands the radio resource allocation period from T1 to T2 (allocation pattern change 1). Then, the changed allocation cycle T2 is notified to the user terminal using L3 signaling. The user terminal that has received the change notification subsequently performs CQI reporting at the allocation cycle T2.

  Alternatively, when CQI feedback is performed under the above-described conditions, it is assumed that the CQI value reported from the user terminal has decreased. In this case, the base station increases the amount of radio resources allocated to this user terminal (allocation pattern change 2). The increase of the radio resource amount may be increased in the frequency domain or may be increased in the time direction. You may increase in both a frequency domain and a time domain. Also, when the number of users in the cell decreases, the amount of CQI feedback radio resources allocated to user terminals can be increased.

  The base station notifies the user terminal of the change of the allocation pattern based on an increase in the amount of radio resources allocated for CQI feedback. At this time, for example, in the notification example of FIG. 1, L3 signaling is used to notify CQI information for the upper two resource blocks or the upper four resource blocks. After receiving the pattern change notification from the base station, the user terminal increases the number of CQI information notification bits and reports to the base station.

  In this way, the radio resource allocation pattern for CQI feedback is variably controlled according to the moving speed of the user terminal, the reception channel quality, and the like. This makes it possible to appropriately perform downlink frequency scheduling while controlling the total number of bits used for CQI notification and improving the utilization efficiency of radio resources.

  FIG. 5 is a configuration example of a base station apparatus according to an embodiment of the present invention. In the base station apparatus 10, the uplink signal received by the antenna 25 is demodulated by the uplink received signal demodulation unit 31, and CQI information is extracted. The extracted CQI information may be the difference between the band average and the measured CQI for the top several RBs as shown in FIG. 1, or a notification of resource block numbers exceeding a predetermined level from the band average as shown in FIG. May be. The extracted CQI information is input to the CQI information reproduction unit 35 and held.

  The CQI information reproduction holding unit 35 reconstructs and stores the reception channel quality for each resource block of each user terminal based on the notified CQI information. Further, the CQI value to be stored is reset to, for example, the average CQI value of the band of the received signal after a certain CQI valid period has elapsed. The CQI information reproducing unit 35 may also reduce the CQI value to be held at a predetermined rate as time elapses from the notification within the CQI valid period.

CQI information extracted by the uplink received signal demodulation section 31, together with the traveling speed information (Doppler frequency) f _D which is supplied from the user terminal, is supplied to the CQI report parameter determination section 32. The CQI notification parameter determination unit 32 determines the CQI notification parameter for each user terminal, for example, at a cycle of about 1 second, based on the CQI report, the moving speed of the user terminal, the traffic type information of data transmitted to each terminal, and the like. .

  The CQI notification parameters include, for example, the number N of higher-order resource blocks that should report CQI, the CQI effective period (reset period) K in the base station, the CQI notification opportunity period (radio resource allocation period), and CQI feedback In the case of employing the uplink radio resource allocated to the user terminal and the method of FIG. 3, the correspondence relationship between the CQI notification opportunity and the level exceeding the band average is included.

  The determined CQI notification parameter is held in the CQI notification parameter holding unit 33 and input to the L3 control signal generation unit 36 for notification to the user terminal. When the determined notification parameter is changed, the L3 control signal generation unit 36 generates an L3 control signal for notifying the user terminal of the change contents. This L3 control signal is scheduled to be transmitted together with user data by the scheduler 13. Further, as described above, referring to the determined current CQI notification parameter, the CQI information reproduction holding unit 35 reproduces the CQI absolute value of each resource block from the demodulated CQI information, and the CQI effective period K The CQI information that has passed is reset.

  On the other hand, packets addressed to each of the user terminals 1 to N are stored in the corresponding buffers 11-1, 11-2, ..., 11-N. The data addressed to each user stored in the buffer and the L3 control channel for notifying the user terminal of the CQI notification parameter are input to the scheduler 13. The scheduler 13 schedules transmission of user data and an L3 control channel based on the reproduced CQI information from each user terminal.

  The user data and the L3 control signal subjected to transmission scheduling by the scheduler 13 are input to the OFDM multiplexing / mapping unit 19 after being encoded and modulated by the channel encoder 15b and the data modulator 16b.

  The L1 / L2 control signal generation unit 14 generates an L1 / L2 control channel associated with the downlink shared data channel for each user. The L1 / L2 control channel is also input to the OFDM multiplexing / mapping unit 19 after being encoded and modulated by the channel encoder 15a and the data modulator 16a. Further, the transmission signal generation unit 17 for other physical channels generates physical channels other than the L1 / L2 control channel and the shared data channel. Examples of such physical channels include pilot channels, physical paging channels, physical broadcast channels, and MBMS (Multimedia Broadcast Multicast Service) channels.

  The OFDM multiplexing / mapping unit 19 multiplexes these channels into orthogonal subcarriers and maps them to the complex plane. Each complex-modulated OFDM subcarrier signal is subjected to inverse fast Fourier transform by the IFFT unit 20, CP (cyclic prefix) is imparted by the CP imparting unit 21, conversion processing to an RF signal by the RF transmission circuit 22, and amplified by the power amplifier 23. Processed and transmitted from antenna 25 via duplexer 24.

  With such a configuration, it is possible to receive CQI information from the user terminal at an appropriate notification timing using an appropriate uplink radio resource with as few bits as possible. And based on the received CQI information, multiuser scheduling can be performed effectively.

  FIG. 6 is a schematic block diagram illustrating a configuration example of a user terminal according to the embodiment of the present invention. In the user terminal 40, a signal received by the antenna 41 is input to the RF receiving circuit 43 via a duplexer 42 and converted into an IF signal. Based on this IF signal, the reception timing estimation unit 45 estimates the reception timing. The FFT unit 44 applies a fast Fourier transform to the IF signal based on the estimated reception timing. The output of the FFT unit 44 is input to the channel estimation unit 46, the downlink L1 / L2 control channel demodulation unit 47, the demapping unit 48, the moving speed estimation unit 55, and the CQI estimation unit.

  The channel estimation unit 46 performs channel estimation, for example, for each subcarrier using the pilot channel. The estimation result is supplied to the data demodulator 49. The downlink L1 / L2 control channel demodulator 47 demodulates the downlink L1 / L2 control channel transmitted from the base station along with the data channel, and receives the data modulation method, channel coding rate, and reception allocated to this user terminal. The resource block number included in the band is extracted and input to the data demodulation unit 49, the channel decoding unit 51, and the demapping unit 48, respectively. The demapping unit 28 generates an original bit string from the output of the FTT unit 44, and the data demodulation unit 49 and the channel decoding unit 51 perform data demodulation and channel decoding according to the modulation scheme and coding rate used on the transmission side. Done. Here, the L3 control channel scheduled and sent together with user data from the base station 10 is taken out, and the CQI measurement parameters included therein are stored in the memory 53.

  The CQI information generation unit 57 refers to the CQI measurement parameter based on the estimation result (CQI measurement value) by the CQI estimation unit 56 and generates CQI information. For example, in the method of FIG. 1, CQI information including the CQI information of the top N resource blocks with the highest CQI value and the resource number is generated. At this time, in the past K communication opportunities, if the top N resource blocks already reported for CQI are included, CQI information of the next resource block is incorporated instead of the resource block. Further, in the method of FIG. 3, referring to information on how to select a resource block that exceeds the corresponding average CQI value for which communication opportunity among the CQI notification parameters, it corresponds for each communication opportunity. Generate CQI information of 0/1 bit string that informs the resource block number exceeding the average CQI value by the level.

  The generated CQI information is transmitted from the transmission control unit 58 to the antenna 41 for each communication opportunity (radio resource allocation period for CQI feedback) designated by the CQI notification parameter from the base station using the designated radio resource. To the base station 10.

On the other hand, the movement speed estimating unit 55 estimates the maximum Doppler frequency _{f D} of the pilot channel from the output spectrum of FFT44. The estimated value is transmitted from the antenna 41 to the base station 10 as the moving speed information of the predetermined uplink channel user terminal 40 by the transmission control unit 58.

  With such a configuration, the number of bits of CQI information notified to the base station can be reduced.

DESCRIPTION OF SYMBOLS 10 Base station 13 Scheduler 31 Uplink received signal demodulation part 32 CQI notification parameter determination part 33 CQI notification parameter holding part 35 CQI information reproduction holding part 36 L3 control signal generation part (upper layer control signal generation part)
40 user terminal 55 moving speed estimation unit 56 CQI estimation unit 57 CQI information generation unit 58 transmission control unit

Claims (13)

A CQI notification method from a user terminal to a base station,
In the notification opportunity given from the base station, the CQI average value of the entire reception band is notified from the user terminal to the base station at a fixed period,
Assuming that there are n notification opportunities during the notification cycle of the CQI average value, the CQI average value is set to the mth (1 ≦ m ≦ n) level in the m-th notification opportunity (1 ≦ m ≦ n). Notifying the base station of resource blocks exceeding the above,
In the base station, the notified CQI average value is held, and the held CQI average value is reduced as time elapses from the notification. Notifying the user terminal of the correspondence relationship between the notification opportunity and the level exceeding the CQI average value in advance,
Further including
The resource block number exceeding the mth level from the CQI average value is notified in the m-th notification opportunity according to the correspondence relationship in the user terminal. CQI notification method. 2. The base station is notified of a bit string obtained by mapping a resource block exceeding the m-th level and other resource blocks with a binary code at the m-th notification opportunity. The CQI notification method according to claim 1. An uplink radio resource allocation method for CQI feedback to a user terminal, comprising:
Informing the user terminal of the allocation period of CQI feedback radio resources for notifying the base station of CQI information and the allocated radio resources;
CQI information notified from the user terminal using the radio resource in the allocation cycle is received and held in the base station;
Reducing the retained CQI information over time from the notification;
Based on at least the held CQI information and the moving speed of the user terminal, at least one of the allocation period of the radio resource for CQI feedback and the amount of radio resources to be allocated is changed. A method for allocating uplink radio resources. An uplink radio resource allocation method for CQI feedback to a user terminal, comprising:
Informing the user terminal of the allocation period of CQI feedback radio resources for notifying the base station of CQI information and the allocated radio resources;
CQI information notified from the user terminal using the radio resource in the allocation cycle is received and held in the base station;
Based on at least the held CQI information and the moving speed of the user terminal, change at least one of the allocation period of the radio resource for CQI feedback and the amount of radio resource to be allocated,
An uplink radio for CQI feedback, wherein the radio resource for CQI feedback is increased in at least one of a frequency domain and a time domain when reception quality at the user terminal has deteriorated based on the CQI information Resource allocation method. The CQI feedback use according to claim 4 or 5, further comprising a step of notifying the user terminal of the allocation cycle, radio resources to be allocated, and change result from the base station through higher layer signaling. A method for allocating uplink radio resources. 6. The method of allocating uplink radio resources for CQI feedback according to claim 4 or 5, wherein when the moving speed of the user terminal is reduced, an allocation period of the CQI feedback radio resources is expanded. A CQI information reproduction holding unit that reproduces CQI information notified from the user terminal and holds the CQI information for each resource block;
A CQI notification parameter determining unit that determines a CQI notification parameter serving as an index when the user terminal notifies the CQI information based on the CQI information;
Have
The CQI information reproduction holding unit resets the held CQI information based on the current CQI notification parameter determined by the CQI notification parameter determination unit when a certain valid period has elapsed from the notification, and The base station apparatus reduces the held CQI information as time elapses from the notification during an effective period of. The CQI notification parameter includes the radio resource allocation cycle for the user terminal to notify the CQI information, the radio resource to be allocated, the effective period, and the top N number that the user terminal should report from the one having better reception quality. The base station apparatus according to claim 8, comprising a number of resource blocks.   The CQI notification parameter should report a radio resource allocation period for the user terminal to notify the CQI information, a radio resource to be allocated, and a resource block that exceeds the average CQI value of the entire reception band at which notification opportunity. The base station apparatus according to claim 8, further comprising: a correspondence relationship for associating a crack. 9. The base according to claim 8, wherein the CQI notification parameter determination unit determines the CQI notification parameter based on at least the CQI information notified from a user terminal and a moving speed of the user terminal. Station equipment. 9. The base station apparatus according to claim 8, further comprising an upper layer control signal generation unit that generates an upper layer control signal that notifies the CQI notification parameter. The base station apparatus according to claim 12, further comprising a scheduler that schedules transmission of the upper layer control signal and user data addressed to each user terminal based on the CQI information.

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