JP5737346B2 - Mobile terminal - Google Patents

Description

  The present invention relates to a mobile terminal, and more particularly to a mobile terminal that receives data transmitted from a radio base station using a plurality of subcarriers.

In a terrestrial digital broadcasting system and an OFDM communication system using OFDM, signal reception power measurement, reception power control, and channel estimation are performed using a common pilot signal time-division multiplexed on a transmission signal.
FIG. 29 is a configuration diagram of a transmission apparatus in an OFDM communication system. A data modulation unit 1 modulates transmission data (user data or control data), for example, QPSK data, and has a complex baseband signal (symbol) having an in-phase component and a quadrature component. Convert to The time division multiplexing unit 2 time-multiplexes pilots of a plurality of symbols before data symbols. The serial / parallel converter 3 converts the input data into parallel data of M symbols and outputs _M subcarrier samples S _{0 to} S _M−1 . An IFFT (Inverse Fast Fourier Transform) unit 4 performs IFFT (Inverse Fourier Transform) processing on the subcarrier samples S _{0 to} S _M-1 input in parallel and synthesizes them, and outputs them as discrete time signals (OFDM signals). The guard interval insertion unit 5 inserts a guard interval into the M-symbol OFDM signal input from the IFFT unit, and the transmission unit (TX) 6 DA-converts the OFDM signal into which the guard interval has been inserted. The frequency is converted from a baseband to a radio band, amplified at a high frequency, and transmitted from the antenna 7.

FIG. 30 is an explanatory diagram of serial-parallel conversion, in which a common pilot P is time-multiplexed ahead of one frame of transmission data. For example, assuming that the common pilot per frame is 4 × M symbols and the transmission data is 28 × M symbols, the serial M / P converter 3 outputs pilot M symbols up to the first four times as parallel data. As a result, M symbols of the transmission data are output 28 times. As a result, the pilot can be time-multiplexed on all subcarriers and transmitted four times in one frame period, and channel compensation (fading compensation) can be performed by estimating the channel for each subcarrier on the receiving side. Become. Note that one OFDM symbol is composed of M symbols.
FIG. 31 is an explanatory diagram of guard interval insertion. The guard interval insertion is to copy the tail part to the head part of IFFT output signal corresponding to M subcarrier samples (= 1 OFDM symbol) as one unit. By inserting the guard interval GI, it becomes possible to eliminate the influence of intersymbol interference due to multipath.

FIG. 32 is a block diagram of an OFDM receiver. The signal output from the transmitting antenna 7 is received by the receiving antenna 8 of the receiving device via the fading propagation path, and the receiving circuit (Rx) 9 converts the RF signal received by the antenna into a baseband signal, The FFT timing synchronization circuit 10 that AD converts a band signal into a digital signal, cuts out and outputs a desired band signal from the AD-converted signal, and performs FFT from a time domain signal including a desired band signal output from the receiving circuit 9. The timing is detected, and the symbol cutout unit 11 cuts out an OFDM symbol at the FFT timing and inputs it to the FFT unit 12. The FFT unit 12 performs FFT processing for each extracted OFDM symbol, and converts it to frequency domain subcarrier samples S ₀ ′ to S _M−1 ′. The channel estimation circuit 13 performs channel estimation for each subcarrier by calculating the correlation between pilot symbols received at regular intervals and a known pilot pattern, and the channel compensation circuit 14 uses the channel estimation value to perform data estimation. Compensates for symbol channel variations. Through the above processing, the transmission data allocated to each subcarrier is demodulated. Thereafter, although not shown, the demodulated subcarrier signal is converted into serial data and then decoded. The above is a case where a pilot is used for channel estimation, but it is also used for measurement of received signal power, SN ratio, and the like.

Incidentally, as shown in FIG. 33, if pilot symbols exist only at the beginning and / or end of a frame, the received power of data between pilots is estimated by the received power of the pilot. When the moving speed of the mobile station is slow as indicated by a solid line A in FIG. 34, for example, when the walking speed is about 4 km / h, the time fluctuation interval of the received electric field strength E is long and the fluctuation width is small. Since the sudden decrease is reduced, it is easy to estimate the received power between pilot symbols. However, when the moving speed of the terminal is fast as indicated by the dotted line B in FIG. 34, the time fluctuation interval of the received electric field strength is shortened and the fluctuation width is also increased. Furthermore, a rapid decrease is likely to occur. As a result, the estimation accuracy of received power between pilot symbols deteriorates. Further, the channel estimation accuracy also deteriorates, and decoding and demodulation is performed using the deteriorated estimation result, so that communication quality deteriorates. In other words, channel estimation accuracy during high-speed movement deteriorates, resulting in deterioration in communication quality and throughput. The following description will be given assuming a specific case.
Assume that there are 100 terminals in the cell and communicating with the base station, and that there are 50 terminals moving at high speed and 50 terminals moving at low speed or stationary. The channel estimation accuracy of a terminal moving at high speed is deteriorated, communication quality is deteriorated, and transmission speed is also lowered. Here, for the 25 terminals out of the 50 high-speed moving terminals, the required communication quality cannot be maintained, and if the transmission rate is 0, the transmission rate of the entire base station is Compared with the case where all terminals are moving at low speed or stationary, the result is 0.75. Thus, when the pilot symbol interval is long, the communication quality of a high-speed moving terminal deteriorates and the transmission rate (throughput) of the entire base station deteriorates.

First Prior Art To deal with the above problem, a method of reducing the common pilot symbol interval and increasing the number of pilot symbols as shown in FIG. But this way,
(1) Since it is a common pilot symbol, the number of pilot symbols increases regardless of the moving speed of the terminal.
(2) Since the data is reduced by the added pilot symbol, the actual transmission rate is degraded.
There are two problems. Hereinafter, specific examples will be described.
The transmission rate of the entire radio frame is assumed to be 10Msps. At this time, for example, it is assumed that the ratio of the number of pilot symbols and the number of data symbols in a normal state is 0.1: 0.7. The remaining 0.2 is a control signal. Therefore, the actual transmission rate is 7 Mbps.
Next, as a measure against high-speed movement, it is assumed that the pilot symbol interval is narrowed and the pilot symbols are inserted twice as described above. At this time, the aforementioned ratio is 0.2: 0.6, and the actual transmission rate is reduced to 6 Mbps. Therefore, if a pilot is added and inserted as a countermeasure against high-speed movement even though a certain terminal is moving at low speed, the actual transmission speed is degraded by 1 Mbps (15%). As described above, if a pilot symbol is simply added, a substantial transmission rate is lowered and a throughput is deteriorated. Therefore, the transmission rate (throughput) of the entire base station is degraded.
Therefore, a method of variably controlling the number of pilot symbols according to the propagation environment has been proposed (see Patent Document 1 and Patent Document 2). In this method, the propagation environment is measured, and control is performed such that the number of pilots is increased when bad and the number of pilots is decreased when good. However, the number of symbols is increased or decreased for each mobile station, and the control becomes complicated. Particularly, since the number of symbols is increased or decreased for each mobile station, there is a problem that scheduling control becomes difficult.

Second Conventional Technology Further, as shown in FIG. 36 (a), a method of adding an individual pilot PD between common pilots in addition to the common pilot P has also been proposed for terminals moving at high speed ( (See Patent Document 3). However, in the dedicated pilot insertion method, it is necessary to perform a control of measuring the propagation environment, inserting the dedicated pilot when it is bad, and not inserting the dedicated pilot when it is good. For this reason, as in the first prior art, it is necessary to perform individual control of the mobile station, and there is a problem that the control becomes complicated and scheduling control becomes difficult. Also, when the individual pilot insertion position is treated as a special position and a specific control signal is inserted as shown in FIG. 36 (b) when the individual pilot is not inserted, the data is reduced and the transmission rate is deteriorated. Arise. That is, even for a terminal moving at a low speed, data cannot be inserted at the dedicated pilot insertion position, and as a result, the same problem as when the pilot symbol interval is narrowed to increase the number of pilot symbols occurs.

JP 2000-151548 A JP 2005-027294 A Japanese Patent Laid-Open No. 2001-197037

As described above, an object of the present invention is to control the number of pilot symbols using a fixed frame pattern.
An object of the present invention is to increase the number of pilot symbols or the number of distributed pilot symbols for a terminal having poor reception quality using a fixed frame pattern, for example, a terminal moving at high speed, This is to reduce the throughput of the base station by reducing the number of pilot symbols or the number of distributed pilot symbols for terminals moving at low speed.
It is an object of the present invention to increase the number of pilot symbols or the number of pilot symbol dispersions for a terminal having poor reception quality with a simple control using a fixed frame pattern, for example, a terminal moving at high speed, thereby improving the accurate reception quality. Measurement, received power measurement, and channel estimation.
An object of the present invention is to facilitate scheduling control.

A first aspect of the present invention is a mobile terminal that receives data transmitted from a radio base station using a plurality of subcarriers, and divides the plurality of subcarriers into a plurality of groups with a certain number of subcarriers. The number of common pilots in a frame having a constant length in the time axis direction constituted by each subcarrier or the number of distributed common pilots is different for each group, and the lengths in the time axis direction and the frequency axis direction are constant. A frame is allocated to each mobile terminal, data to be transmitted to each mobile terminal is mapped to each frame having a fixed length allocated to the mobile terminal, and the data transmitted from a radio base station to a plurality of mobile terminals is mapped by frequency multiplexing. A wireless receiving unit for receiving the received frame.
A second aspect of the present invention is a mobile terminal that receives data transmitted from a radio base station using a plurality of subcarriers, and has a different number of common pilots or different number of common pilots in the time axis direction and frequency axis direction. A frame pattern generator that repeatedly generates at least two types of frame patterns having a constant length, and a plurality of subcarriers in the frequency axis direction are divided into a plurality of groups with a certain number of subcarriers, and the generated frame patterns are Data mapping for assigning each frame having a fixed length in the time axis direction configured with subcarriers of each group to each mobile terminal and mapping data to be transmitted to each mobile terminal to each frame allocated to the mobile terminal And a transmission for transmitting each frame mapped with data to a plurality of mobile terminals by frequency multiplexing. Radio receiving section for receiving parts and the frame in which the data is mapped transmitted from the radio base station having a, and a.

According to the present invention, at least two types of frames having different numbers of common pilots or at least two types of frames having different numbers of common pilots are combined in combination of one or more, and data is mapped to each frame to set each set. Since it is repeatedly transmitted to the mobile terminal, the number of pilot symbols can be controlled using a fixed frame pattern.
Further, according to the present invention, a plurality of subcarriers are divided into two groups, and the number of common pilots or the number of common pilots in a frame composed of the first group of subcarriers and a frame composed of the second group of subcarriers is divided. Since the number of distributions is different and data is mapped to each frame composed of the first and second groups of subcarriers and repeatedly transmitted to the mobile terminal, pilot symbols are used using a fixed frame pattern. The number can be controlled.
According to the present invention, a mobile terminal with poor reception quality is assigned a frame with a large number of common pilots or a large number of dispersions, and a mobile terminal with good reception quality is assigned a frame with a small number of common pilots or a small number of dispersions. Since the data addressed to the corresponding terminal is mapped to each frame and transmitted, the number of pilot symbols is set for a terminal having a poor reception environment, for example, a terminal moving at high speed, with a simple control using a fixed frame pattern. As a result, accurate reception quality measurement, reception power measurement, and channel estimation can be performed.
According to the present invention, since the mobile terminals are grouped for each frame constituting the combination and the transmission scheduling process is performed based on the reception quality measurement result reported from the mobile terminal for each group, the fixed frame pattern Schedule transmission can be easily controlled for each frame.
According to the present invention, based on a reception state of a mobile terminal in communication in a cell, a combination of frames constituting the set is determined, a mobile terminal is assigned to each frame, and the determined combination of frames is assigned to the mobile terminal. Since the frame assigned to the mobile terminal is notified, the optimum combination is determined based on the reception state of the mobile terminal in communication in the cell and communication is performed, so that the throughput of the base station can be improved. .

It is a block diagram of the fixed frame pattern FRPT of this invention. It is explanatory drawing of the radio | wireless communications system using subcarriers, such as OFDM. It is a fixed frame pattern explanatory drawing. It is explanatory drawing of frequency multiplexing. FIG. 3 is a configuration diagram of a base station BTS of the first embodiment. FIG. 3 is a configuration diagram of a mobile station according to the first embodiment. FIG. 6 is an explanatory diagram of a frame setting sequence of a base station BTS for a mobile station UEi. It is another block diagram of the mapping part provided with the frequency multiplexing function. It is a block diagram provided with the code | symbol multiplexing function. This is a case where the position of the pilot symbol in the frequency direction is shifted in the time direction. FIG. 6 is a configuration diagram of a base station BTS of a second embodiment. FIG. 6 is a configuration diagram of a mobile station according to a second embodiment. FIG. 4 is an explanatory diagram of a frame setting sequence in a mobile station UEi. FIG. 6 is a configuration diagram of a base station BTS of a third embodiment. It is CQI table explanatory drawing. It is an explanatory view of scheduling processing in a base station. FIG. 10 is a configuration diagram of a base station BTS of a fourth embodiment. FIG. 10 is an explanatory diagram of scheduling processing of a base station in the fourth embodiment. FIG. 10 is an explanatory diagram of a fifth embodiment for changing the frame pattern FRPT. FIG. 10 is a configuration diagram of a base station according to a fifth embodiment. FIG. 6 is an explanatory diagram of a frame pattern type and a frame setting sequence of a base station BTS. It is explanatory drawing of the multiplexing method (Localized OFDMA) which allocates the continuous subcarrier to each user (mobile terminal), and frequency-multiplexes. It is explanatory drawing of the multiplexing method (Distributed OFDMA) which decides the user to use for every subcarrier and carries out frequency multiplexing. This is an example of frequency division and frame configuration when two users are moving at low speed and two users are moving at high speed. This is a frequency division and frame configuration example when the ratio of the number of terminals moving at low speed to the number of terminals moving at high speed is 3: 1. It is a frequency division and frame configuration example when data is frequency-multiplexed to one terminal moving at low speed and one terminal moving at high speed. It is a frequency division and the structural example of a flame | frame when the subcarrier for low speed movement and the subcarrier for high speed movement are disperse | distributed. FIG. 10 is a configuration diagram of a base station BTS of a sixth embodiment. It is a block diagram of the transmitter in an OFDM communication system. It is serial parallel conversion explanatory drawing. It is guard interval insertion explanatory drawing. It is a block diagram of an OFDM receiver. It is frame explanatory drawing in which a pilot symbol exists only in the head and the end. It is explanatory drawing of the problem of the flame | frame of FIG. It is frame explanatory drawing which narrowed the common pilot symbol space | interval and increased the number of pilot symbols. FIG. 5 is an explanatory diagram of a frame in which individual pilot PD is added between common pilots in addition to common pilot P.

In a radio base station that performs data communication using subcarriers, a frame pattern FRPT is formed by combining at least two types of frames having different numbers of common pilots or at least two types of frames having different numbers of shared pilots. Assign a frame with a large number of common pilots or a large number of dispersions to a mobile terminal with poor reception quality, and assign a frame with a small number of common pilots or a small number of dispersions to a mobile terminal with good reception quality, corresponding to each frame Each set is repeatedly transmitted by mapping data addressed to the mobile terminal.
FIG. 1 is a configuration diagram of a fixed frame pattern FRPT of the present invention. In FIG. 1 (A), a plurality of frames F _L and F _H having the same number of common pilots in one frame and different pilot symbol arrangements are alternately arranged. It is arranged.
Frame _FL is a frame for a mobile terminal having a small propagation number of pilot symbols P and a good propagation environment, for example, a low-speed mobile terminal, and frame F _H is a mobile terminal having a large number of pilot symbol dispersions and a poor propagation environment. For example, a frame for a high-speed mobile terminal.
The fluctuation interval of the received power in the terminal moving at high speed is short and the vibration width is large. For this reason, the data of the terminal moving at high speed is mapped to the frame F _H that can shorten the measurement interval of the received power. On the other hand, the fluctuation interval of the received power in the terminal moving at low speed is long and the vibration width is small. Therefore, data in the low-speed mobile terminal maps the frame F _L for low-speed movement. Then, these two frames F _L, repeatedly transmits a fixed frame pattern FRPT to set the F _H. Thereby, it is possible to improve the reception power measurement accuracy and the channel estimation accuracy for both the high-speed moving terminal and the low-speed moving terminal, thereby improving the communication quality. Further, the number of pilot symbols may be a frame F _L, the same the same for data transmission speed during low speed movement and during high-speed movement in F _H.
FIG. 1 (B), and greater than the number of pilot symbols in a frame F _L for low-speed mobile terminal number of pilot symbols in a frame F _H for high speed mobile terminal, and is an example of many distributed number. According to the frame pattern of FIG. 1 (B), although the data transmission rate of a high-speed mobile terminal is reduced, the number of pilot symbols is increased, so that received power measurement and channel estimation can be performed with high accuracy.
The number of frames F _L and the frame F _H in a fixed frame pattern FRPT may be unequal. The more propagation environment favorable mobile terminal, and more than the number of frames F _L frames F _H the number of, The more propagation environment is poor mobile terminal and greater than the number the number of frames F _L of the frame F _H .

(A) First embodiment-Frame pattern FRPT
FIG. 2 is an explanatory diagram of a radio communication system using subcarriers such as OFDM, and it is assumed that a base station BTS1 and mobile stations (mobile terminals) UE1 to UE6 in a certain cell CL are communicating. At this time, it is assumed that the mobile station UE1 is stationary, the mobile stations UE2 and UE3 are moving at a walking speed (about 4 km / h), and these mobile stations are moving at a low speed. On the other hand, the mobile stations UE4 to UE6 are moving (60 km / h) by car, and these mobile stations are defined as moving at high speed. Note that the ratio of terminals moving at low speed to terminals moving at high speed is 1: 1.
When the ratio of the number of mobile stations moving at a low speed to the number of mobile stations moving at a high speed is approximately 1: 1, a pair of low speed frames _FL and high speed frames F _H is provided as shown in FIG. The fixed frame pattern FRPT is repeatedly generated and transmitted. In each frame, the horizontal direction is time (OFDM symbol) as in FIG. 33, the vertical direction is subcarriers, one frame is composed of, for example, 32 OFDM symbols, and one OFDM symbol is composed of M subcarriers. ing.
Frame F _L, OFDM symbol number of common pilots in F _H only are different, but the arrangement pattern of the same to each other, the common pilot symbols P to the two front and rear positions of the frame F _L the frame for low-speed is located However, in the high-speed frame F _H , five common pilot symbols P ′ are equally arranged in one frame. This is because the pilot signal interval can be increased because the fluctuation interval of the received electric field strength is long and the vibration width is small in the terminal moving at low speed, and the fluctuation interval of the received electric field strength is short and the vibration width is large in the terminal moving at high speed. This is because the measurement interval of received power must be shortened. Note that the number of OFDM symbols of the common pilot in the low speed frame _FL and the high speed frame F _H may be different as shown in FIG.
The low-speed frame F _L data destined plurality of low-speed mobile station are multiplexed, the high-speed frame F _H data destined plurality of high-speed mobile station are multiplexed. Multiplexing methods include frequency multiplexing, code multiplexing, and time division multiplexing. FIG. 4 is an explanatory diagram of frequency multiplexing, in which M (= n × N) subcarriers f _{0 to} f _nN-1 of each OFDM symbol are divided into n groups F _{0 to} F _n-1 in units of N, Frequency multiplexing is performed by mapping predetermined terminal-oriented data to the subcarrier groups of each group F _{0 to} F _n−1 .
In FIG. 3, pilots are arranged on all subcarriers, that is, continuously arranged in the frequency direction. However, pilots can be arranged at regular intervals or at irregular intervals.

Configuration of Base Station BTS FIG. 5 is a configuration diagram of the base station BTS, and the frame pattern generator 21 repeatedly generates a frame pattern FRPT formed by inserting pilot symbols at appropriate positions as shown in FIG. The transmission data processing unit 22 includes a multiplexing unit 22a, an encoding unit 22b, and a data modulation unit 22c. The multiplexing unit 22a multiplexes control data, user data, and other data (movement speed request data and use frame setting data described later). The encoding unit 22b encodes the output data of the multiplexing unit, and the data modulation unit 22c modulates the encoded data with QPSK, 16QAM, or the like. The mapping unit 23 is a predetermined sub-carrier of each OFDM symbol of the high-speed frame F _H or high-speed frame F _L of the frame pattern FRPT data depending on whether the destination mobile station of the user data is low mobile station or a fast moving station ( (See FIG. 4). The OFDM transmitter 24 performs IFFT processing on n × N subcarrier samples, combines them, inserts a guard interval GI into the combined time signal, and the radio transmitter 25 increases the frequency of the baseband signal to the radio frequency. After the conversion, it is amplified and transmitted from the antenna 26.
The radio receiving unit 27 down-converts the frequency of the radio signal received from the mobile station to the baseband frequency, and the demodulating unit 28 demodulates the baseband signal by applying demodulation processing. The reception data processing unit 29 includes a decoding unit 29a and a demultiplexing unit 29b, the decoding unit 29a performs error correction decoding processing on the demodulation result, and the demultiplexing unit 29b determines the uplink transmission data, control data, and moving speed data from the user based on the decoding result Are output separately.
The frame selection / setting unit 30 includes a frame control unit 30a, a moving speed determination unit 30b, and a low speed / high speed holding unit 30c. The frame control unit 30a periodically requests the moving speed of each mobile station and sets a frame to be used by the mobile station based on the moving speed. The moving speed determination unit 30b determines whether the mobile station is moving at high speed or low speed based on the moving speed V _EUi (i = 1, 2,...) Received from the mobile station and the threshold value Vth. The determination is made and the determination result is input to the frame control unit 30a. The frame control unit 30a divides the mobile station into a low speed terminal group and a high speed terminal group, and the low speed / high speed holding unit 30c determines whether each terminal belongs to the low speed group or the high speed group. Mapping unit 23 maps a predetermined frame F _H or F _L of the frame pattern FRPT to identify the group to which belongs the destination mobile station of the downlink user data based on the contents held in the low speed and high speed holding portion 30c.
When the moving speed is requested from the frame control unit 30a, the transmission information creating unit 31 creates moving speed request data and transmits it to the mobile station via the transmission data processing unit 22. The transmission information creation unit 31 creates use frame setting data and notifies the transmission data processing unit 22 to notify the mobile station of the frame when the frame control unit 30a is instructed to notify the mobile station of the frame to be set. To the mobile station.

Configuration of Mobile Station FIG. 6 is a configuration diagram of a mobile station. A radio reception unit 41 converts a radio signal from a base station received by an antenna 40 into a baseband signal, and a demodulation unit 42 uses a baseband signal. Demodulate the received signal. The reception data processing unit 43 includes a decoding unit 43a, a separation unit 43b, a symbol timing generation unit 43c, a moving speed measurement unit 43d, a CIR measurement unit 43e, and a CQI calculation unit 43f. The decoding unit 43a performs error correction decoding processing on the demodulation result to demodulate the received data, and the separation unit 43b separates and outputs user data and control data. The symbol timing generation unit 43c generates the symbol timings of the frames F _H and F _L constituting the frame pattern FRPT, and the moving speed measurement unit 43d measures the drop interval (fading pitch) of the received electric field strength using the pilot symbols. Thus, the moving speed is estimated. The specific method of measuring the moving speed is well known (see, for example, Japanese Patent Laid-Open No. 10-79701 (US Pat. No. 6,335,923B2)), and therefore will not be described in detail. The CQI measurement unit 43e measures the carrier interference ratio (CIR) using the pilot symbols, and the CQI calculation unit 43f calculates a CQI (Channel Quality Indicator) value corresponding to the CIR. In addition, it can also be configured to measure the SIR and calculate the CQI value from the SIR. CQI takes a value of 1 to 30, and the larger the CIR or SIR, the larger the value, and the base station determines the transport block size (number of bits) TBS, the number of multicodes (in the case of code multiplexing) based on the CQI value, Determine the modulation type. The base station scheduling process using CQI will be described in the third embodiment.

When the used frame control unit 44 receives the moving speed request data from the base station, it instructs the moving speed measuring unit 43d to measure the moving speed, and the moving speed measuring unit 43d measures the moving speed using the pilot symbol of the currently used frame. . Also, when the used frame control unit 44 receives the frame setting data instructing the used frame from the base station BTS, the frame is input to the moving speed measuring unit 43d, the CIR measuring unit 43e, a channel estimation unit and a received power measuring unit (not shown). To do.
The transmission data processing unit 45 includes a multiplexing unit 45a and an encoding unit 45b, the multiplexing unit 45a multiplexes control data, uplink user data, and other data (movement speed, CQI value), and the encoding unit 45b is a multiplexing unit. Encode the output data. The modulation unit 46 QPSK modulates the transmission data, for example, and the wireless transmission unit 47 converts the modulated signal into a wireless signal, amplifies it, and transmits it from the antenna 40.
Although not shown, the mobile station performs channel estimation using a pilot included in its own frame, a channel estimation unit that performs channel compensation based on the channel estimation value, and received power that measures received power using the pilot. A measurement unit and a reception power control unit that controls reception power based on the reception power are provided as appropriate.

Frame Setting Sequence FIG. 7 is an explanatory diagram of the frame setting sequence of the base station BTS for the mobile station UEi.
The radio base station BTS requests the mobile station UEi (i = 1, 2,...) To measure the moving speed. Each mobile station UEi that received the request measure their respective movement speed V _UE1 ~V _{UE 6,} and notifies the base station BTS. The base station BTS compares the moving speed transmitted from the mobile station with the threshold value Vth to determine whether the moving speed is high or low. That is,
Vth ≧ V _UE1
In the case of
Vth <V _UE1
In this case, it is determined that the mobile station is moving at high speed, and using this result, the base station BTS groups the mobile stations UEi into terminals moving at high speed and terminals moving at low speed. Subsequently, the base station BTS determines a frame to be used according to the moving speed for each mobile station UEi, and notifies the mobile station of the result. For example, if the mobile station UE2 in FIG. 2, the base station BTS from a Vth ≧ V _UE1 determines that moving at low speed, an instruction to use a low-speed frame F _L to the mobile station UE2. Also, when the mobile station UE 5, the base station BTS from a Vth <V _UE1 determines that moving at high speed, an instruction to use a high-speed frame F _H to the mobile station UE 5.
Each mobile station UEi performs frame setting to the transmission / reception unit in accordance with an instruction from the base station BTS, and when the setting is completed, notifies the base station BTS of the completion of setting.
Thereafter, the base station BTS transmits multiplexes the frame F _H or F _L corresponding user data to the destination mobile station, the mobile station UEi is performing communication using frames indicated in the above sequence. Then, concurrently with providing data communication, performing measurements and channel estimation of the reception power using the pilot in the frame F _H or F _L assigned to them. The base station and each mobile station perform the above sequence periodically to continue communication.
In instruction method of the frame, the frame number of the low speed frame F _L to 0, the frame numbers of the high-speed frame F _H and 1, may notify the frame number. Further, it may be notified that each frame is not used / used.

Multiplexing methods There are frequency multiplexing, code multiplexing, and time division multiplexing as methods for multiplexing downlink transmission data addressed to a plurality of mobile stations, and frequency multiplexing has been described with reference to FIG. That is, the mapping unit 23 in FIG. 5 performs frequency multiplexing by mapping downlink transmission data addressed to a plurality of mobile stations to subcarriers in n groups F _{0 to} F _n−1 of each OFDM symbol (see FIG. 4). can do.
FIG. 8 is another configuration diagram of a mapping unit having a frequency multiplexing function. The mapping unit 23 is a _first to _n- th mapping unit 23a _{0 to} 23a _n-1 that maps data addressed to each terminal to sub-carriers of _n sub-carrier groups F _{0 to} F _n-1 (see FIG. 4). A distribution unit 23b that distributes data addressed to the mobile station to the first to n-th mapping units and a distribution control unit 23c that controls data distribution are provided. Allocation control unit 23c controls the distributing unit 23b, if the timing of the high-speed frame F _H, distributes the data and pilots for a high-speed mobile station to the first to n mapping unit 23a ₀ ~23a _n-1, each mapping unit 23a _{0 to} 23a _n-1 map the input data and pilot addressed to the high-speed mobile station to predetermined subcarriers and input them to the OFDM transmission processing unit 24. Further, the distribution control unit 23c controls the distributing unit 23b, if the timing of the low speed frames F _L, distributes the data and pilots for low-speed mobile station to the first to n mapping unit 23a ₀ ~23a _n-1, each The mapping units 23a _{0 to} 23a _n-1 map the input data and pilot addressed to the low-speed mobile station to predetermined subcarriers and input the data to the OFDM transmission processing unit 24.

FIG. 9 is a configuration diagram including a code multiplexing function, and a code multiplexing unit 33 is provided between the mapping unit 23 and the OFDM transmission processing unit 24. The mapping unit 23 maps the transmission data addressed to the mobile station to all the subcarriers f _{0 to} f _nN−1 , the first to n-th mapping units 23d _{0 to} 23d _n−1 , and the data addressed to each mobile station A distribution unit 23e that distributes to the 1st to n-th mapping units and a distribution control unit 23f that controls data distribution are provided. Allocation control unit 23f controls the distributing unit 23e if the timing of the high-speed frame F _H, distributes the data and pilots for a high-speed mobile station to the first to n mapping unit 23d ₀ ~23d _n-1, each mapping unit 23d _{0 to} 23d _n-1 map the input data and pilot addressed to the high-speed mobile station to the subcarriers f _{0 to} f _nN-1 and input them to the code multiplier 33a of the code multiplexer 33. Further, the distribution control unit 23e controls the distributing unit 23e if the timing of the low speed frames F _L, distributes the data and pilots for low-speed mobile station to the first to n mapping unit 23d ₀ ~23d _n-1, each mapping unit 23d ₀ ~23d _n-1 inputs and maps the data and pilots for low-speed mobile station inputted to the subcarrier f ₀ ~f _nN-1 to the code multiplication unit 33a. The multipliers MLP _{0 to} MLP _n-1 of the code multiplier 33a multiply the subcarrier samples output from the mapping units 23d _{0 to} 23dn _-1 by user-specific spreading codes, and the combiner 33b outputs each multiplier. Are combined (code multiplexed) and input to the OFDM transmission processing unit 24.

As described above, according to the first embodiment, the number of pilot symbols is increased in the frame F _H used by the mobile station moving at high speed, and the pilot symbol interval is narrowed. Measurement accuracy and channel estimation accuracy are improved. Thereby, the communication quality is improved, and the number of retransmissions due to the improved communication quality is reduced. On the other hand, long pilot symbol interval in a frame F _L for the mobile station moving at low speed is used, which enables high-speed data transmission. As described above, the communication quality can be maintained regardless of the moving speed of the terminal in total, and the throughput of the base station can be improved by preventing the substantial transmission speed from being lowered.
In the above description, the position of the common pilot symbol in the frequency direction in the high speed frame F _H is constant at a certain time. However, as shown in FIG. 10A, the position of the pilot symbol in the frequency direction is in the time direction. It does not matter even if it is shifted. Furthermore, as shown in FIG. 10B, a scattered pilot in which common pilot symbols are distributed may be used.
In the above description, the frame to be used is determined based on the moving speed of the mobile station, but reception quality (CIR, SIR, etc.) can be used instead of the moving speed. This is because the reception quality deteriorates when the movement speed is fast, and the reception quality improves when the movement speed is slow. The same applies to the other embodiments.

(B) Second Embodiment In the first embodiment, each mobile station UEi measures the moving speed, reports the moving speed to the base station BTS, and the base station uses the frame used by the mobile station based on the moving speed. Is determined and set in the mobile station. In the second embodiment, the frame used by the mobile station itself is determined.
FIG. 11 is a block diagram of the base station BTS of the second embodiment, and the same reference numerals are given to the same parts as those of the base station of the first embodiment of FIG. The difference is that (1) the base station sends the frame pattern type and the threshold for high-speed / low-speed identification to the mobile station, and (2) the frame selection / setting unit 30 is used for the mobile station based on the moving speed. This is the point that the mobile station receives the used frame of the mobile station from the mobile station and groups the terminals.
The frame control unit 30a of the frame selection / setting unit 30 controls the transmission information creation unit 31 in advance to set the frame pattern FRPT type and the threshold value Vth for high speed / low speed identification to each mobile station via the transmission data processing unit 22. Send. Frame pattern FRPT shall have one at the high-speed frame F _H and the low-speed frame F _L as shown in FIG. Also, if the frame control unit 30a receives information on the frames F _H and F _L used by the mobile station from the mobile station, the mobile station is moving at high speed or moving at low speed based on the frame information And is stored in the low-speed / high-speed holding unit 30c.

FIG. 12 is a block diagram of the mobile station UEi of the second embodiment, and the same reference numerals are given to the same parts as those of the mobile station of the first embodiment of FIG. The difference is that (1) a frame selection / setting unit 48 is provided instead of the used frame control unit 44, and (2) the frame selection / setting unit 48 is based on the moving speed V _{UE of the} own station and the threshold Vth. you can use the high-speed frame F _H Te is that notifies the base station BTS to determine whether to use the low-speed frame F _L.
FIG. 13 is an explanatory diagram of a frame setting sequence in the mobile station UEi.
The radio base station BTS transmits the frame pattern FRPT type and the threshold value Vth for high speed / low speed identification to each mobile station UEi in advance, and the mobile station stores the received data. The mobile station UEi periodically measures its own moving speed V _UE , compares the moving speed V _UE with the previously notified threshold value Vth, and determines whether it is moving at high speed or low speed based on its magnitude To do. Then, if the mobile station UEi uses the high-speed frame F _H on the basis of the determination result, along with to determine whether to use the low-speed frame F _L notifies the base station BTS, to configure the frame to the transceiver unit If the setting is completed, the base station BTS is notified of the setting completion.
Thereafter, the base station BTS transmits multiplexes the frame F _H or F _L corresponding user data to the destination mobile station, the mobile station UEi is communication using a frame F _H or F _L determined in the above sequence Do. At the same time when performing data communication, performing measurements and channel estimation of the received power by using the pilots in the own frame F _H or F _L. According to the second embodiment, an effect equivalent to that of the first embodiment can be obtained.

(C) In the third embodiment the third embodiment, groups the mobile station in the high-speed frame F _H and the low-speed frame F _L constituting the frame pattern FRPT, transmission scheduling process for the high-speed mobile station group in the high-speed frame timing Is performed based on CQI (Channel Quality Indication), and transmission scheduling processing of a low-speed mobile station group is performed based on CQI at low-speed frame timing. That is, the third embodiment performs scheduling processing in accordance with the frame timing.
FIG. 14 is a block diagram of the base station BTS of the third embodiment, and the same reference numerals are given to the same parts as those of the base station of the first embodiment of FIG. The differences are: (1) a buffer 51 is provided to store downlink transmission data addressed to each mobile station, and (2) transmission scheduling processing of high-speed mobile stations is performed based on CQI from each mobile station at high-speed frame timing. (3) The scheduler 52 is provided with a CQI table shown in FIG. 15 in that a scheduler 52 is provided that performs transmission scheduling processing of a low-speed mobile station group based on CQI from each mobile station at low-speed frame timing. From this table, the transport block size (number of bits) TBS, the number of multi-codes (in the case of code multiplexing) and the modulation type are determined and scheduling is performed according to the CQI.

FIG. 16 is an explanatory diagram of scheduling processing in the base station.
Each mobile station UEi periodically calculates CQI, and notifies the base station BTS of the CQI and the type of frame currently used by the mobile station (high-speed frame F _H or low-speed frame F _L ). The base station BTS receives the CQI and the used frame from each mobile station UEi, performs scheduling, and transmits a control signal and downlink data to each mobile station based on the scheduling.
When scheduling, the scheduler 52 receives the CQI and the frame being used by the mobile station from each mobile station UEi (step 101), and if the timing of the high-speed frame F _H , the mobile station group using the high-speed frame is selected. selected, also, if the timing of the low speed frames F _L, selects a mobile station group using low-speed frames (step 102). Next, the scheduler 52 determines a priority order to which mobile station data is preferentially transmitted based on the selected CQI value of each mobile station (step 103). The higher the CQI value, the higher the priority.
When the priority order is determined, the scheduler 52 selects the modulation method, coding rate, number of data, etc. used for transmission to each mobile station from the CQI table (FIG. 14) based on the CQI (step 104), The transmission data for each mobile station stored in the buffer 51 is selected according to the priority order, and is frequency-multiplexed and transmitted in the corresponding frame (step 105). Thereafter, the above process is repeated, and data is transmitted to the high-speed mobile terminal group and the low-speed mobile terminal group alternately in the order of higher priority.
Note that the control information such as the modulation scheme and coding rate selected in step 104 may be transmitted simultaneously with the transmission data, or the control information may be transmitted in advance and then transmitted.
According to the third embodiment, transmission scheduling processing of the high-speed mobile station group is performed based on the CIR received from each mobile station at the high-speed frame timing, and transmission scheduling processing of the low-speed mobile station group is similarly performed at the low-speed frame timing. Can be done based on CIR.

(D) Fourth Embodiment FIG. 17 is a configuration diagram of a base station BTS of a fourth embodiment. In the third embodiment, one scheduler performs transmission scheduling processing for a high-speed mobile station group at a high-speed frame timing and performs transmission scheduling processing for a low-speed mobile station group at a low-speed frame timing. In the fourth embodiment, As a scheduler, a high-speed scheduler 52a and a low-speed scheduler 52b are provided, and a classification unit 53 is provided.
FIG. 18 is an explanatory diagram of base station scheduling processing in the fourth embodiment.
Each mobile station UEi periodically calculates CQI, and notifies the base station BTS of the CQI and the type of frame currently used by the mobile station (high-speed frame F _H or low-speed frame F _L ). The base station BTS receives the CQI and the used frame from each mobile station UEi, classifies the mobile station into a high-speed group and a low-speed group, performs scheduling for each group, and transmits a control signal to each mobile station based on the scheduling. Transmit downlink data.
That is, the classification unit 53 groups mobile stations based on the type of used frame (high-speed frame F _H or low-speed frame F _L ) sent together with the CQI, and from the mobile station using the high-speed frame F _H sent to the high-speed scheduler 52a of CQI with mobile station identification number, and sends the low-speed scheduler 52b the CQI from the mobile stations using low-speed frame F _L with the mobile station identification number.

High-speed scheduler 52a performs the transmission scheduling process for the high-speed mobile station group by the third embodiment and the same processing at the timing of the high-speed frame F _H, the low-speed scheduler 52b transmission scheduling process for the low-speed mobile station group at timing for low-speed frames I do.
That is, the high-speed scheduler 52a determines the priority order to which data is preferentially transmitted based on the CQI value of the high-speed mobile station, and the low-speed scheduler 52b determines the CQI value of the low-speed mobile station. Based on this, a priority order to determine which mobile station to transmit data preferentially is determined (step 201). When the priority determination is completed, the high-speed scheduler 52a and the low-speed suzuki 52b select the modulation method, coding rate, number of data, etc. used for transmission to each mobile station from the CQI table based on the CQI. (Step 202). Next, the high-speed scheduler 52a selects transmission data for each high-speed mobile station stored in the buffer 51 in accordance with the priority order at the high-speed frame timing, and performs frequency multiplexing to transmit. Further, the low-speed scheduler 52b selects transmission data for each low-speed mobile station stored in the buffer 51 according to the priority order at the low-speed frame timing, and performs frequency-multiplexing and transmission (step 203).
According to the fourth embodiment, similarly to the first embodiment, transmission scheduling processing of the high-speed mobile station group is performed based on the CIR at the high-speed frame timing, and transmission scheduling processing of the low-speed mobile station group is performed at the low-speed frame timing as the CIR. Can be done on the basis of Also, according to the fourth embodiment, scheduling is performed using two schedulers, so that scheduling processing can be performed with a margin.

(E) in the fifth embodiment the first embodiment, substantially the ratio of the number of mobile stations of a mobile station number and moving at high speed in the low speed movement 1: since it is a 1, and the low-speed frame F _L in the frame pattern FRPT The ratio of the number of high-speed frames F _H is fixed to 1: 1 (see FIG. 19 (a)) In the fifth embodiment, the ratio of the number of mobile stations moving at a low speed to the number of mobile stations moving at a high speed When changes dynamically, to control the ratio ratio of the number of low-speed frame F _L and the high-speed frame F _H in the frame pattern FRPT depending on (hereinafter referred to as Low High ratio) (low-speed high-speed frame ratio). for example, If the low-speed high-speed ratio is 2: 1, the low-speed high-speed frame ratio in the frame pattern FRPT is 2: 1 and three frames are repeatedly transmitted as one set as shown in Fig. 19 (b). If the low-speed and high-speed frame ratio is not changed, the throughput of the entire base station is reduced. For example, if the low-speed high-speed frame ratio is 1: 1 even though the low-speed high-speed ratio is 2: 1, the low-speed mobile station may not be accommodated in one low-speed frame, and the overall throughput of the base station may be reduced. For this reason, in the fifth embodiment, the low-speed / high-speed frame ratio is changed according to the low-speed / high-speed ratio as described above.
FIG. 20 is a block diagram of the base station of the fifth embodiment, and the same reference numerals are given to the same parts as those of the first embodiment of FIG. The difference from the first embodiment is that (1) a frame pattern & frame setting unit 61 is provided instead of the frame selection / setting unit 30, and (2) the frame pattern type determined by the frame pattern & frame setting unit 61. The frame pattern generator 21 generates a predetermined frame pattern FRPT based on the above.
The frame pattern & frame setting unit 61 compares the moving speed V _EU and the high / low speed threshold Vth and determines whether the mobile station is moving at high speed or low speed based on the magnitude thereof. And a frame pattern & frame control unit 61b for determining a frame pattern FRPT used by the mobile station and a frame pattern FRPT based on the low-speed high-speed ratio and the number of mobile stations in communication in the cell, and a mobile station A low-speed / high-speed holding unit 61c is provided for storing whether the frame is moving at a high speed or a low-speed movement every time, and storing a used frame.

FIG. 21 is an explanatory diagram of the frame pattern type and frame setting sequence of the base station BTS.
The frame pattern & frame control unit 61b of the radio base station BTS controls the information setting unit 31 to request each mobile station UEi (i = 1, 2,...) To measure the moving speed. Each mobile station UEi that received the request measure their respective movement speed V _UE1 ~V _{UE 6,} and notifies the base station BTS. The frame pattern & frame control unit 61b compares the moving speed V _EUi transmitted from the mobile station with the threshold value Vth to determine whether the mobile station is moving at high speed or low speed, and determines the number of mobile stations in communication in the cell and the high speed movement. Count the number of mobile stations in the middle and the number of mobile stations moving at a low speed. When the high-speed and low-speed identification is completed for all the mobile stations in communication in the cell, the frame pattern & frame control unit 61b calculates the low-speed high-speed ratio in the cell, and the number of mobile stations in communication in the cell and this low-speed high-speed ratio. The type of frame pattern is determined based on the ratio. For example, if the low-speed / high-speed ratio is 2: 1 and the number of mobile stations is large, the frame pattern & frame control unit 61b determines that the frame pattern shown in FIG. The frame to be used is determined for each station.
After that, the frame pattern & frame control unit 61b notifies each mobile station of the determined frame pattern type and the used frame, and each mobile station UEi follows the instruction from the base station BTS to the frame pattern and frame to the transmission / reception unit. If the setting is completed, the base station BTS is notified of the completion of the setting. The notification of the frame pattern and the used frame to the mobile station is performed prior to the actual switching timing because it is necessary to change the setting of the transceiver.
Thereafter, the base station BTS multiplexes and transmits user data in a frame corresponding to the destination mobile station, and each mobile station UEi extracts data addressed to itself from the frame indicated in the above sequence.
According to the fifth embodiment, it becomes possible to use an appropriate frame pattern based on the number of mobile stations moving at high speed and low speed, resulting in improved channel estimation accuracy and improved throughput of the base station as a whole. To do.

(F) Sixth Embodiment In the above embodiments, at least two types of frames having different numbers of common pilots or at least two types of frames having different numbers of common pilots are combined, and data is stored in each frame. And each set was repeatedly transmitted to the mobile terminal. In the sixth embodiment, a plurality of subcarriers are divided into two groups, and the number of common pilots or the number of shared pilot dispersions in a frame composed of subcarriers in the first group and a frame composed of subcarriers in the second group And data is mapped to each frame configured by the subcarriers of the first and second groups and repeatedly transmitted to the mobile terminal.
In order to frequency multiplex in OFDMA (Orthogonal Frequency Division Multiplexing Access), as shown in FIG. 22, an allocation method for assigning consecutive subcarriers to each user (mobile terminal) and a method for each subcarrier as shown in FIG. There is a method of multiplexing by deciding users. In FIG. 23, subcarriers to which the same user number is assigned are subcarriers assigned to the user and are used only by the user. The multiplexing method in FIG. 22 is called Localized OFDMA, and the multiplexing method in FIG. 23 is called Distributed OFDMA. In the following, the sixth embodiment will be described using Localized OFDMA, but Distributed OFDMA is also applicable.
The sixth embodiment, as shown in FIG. 24, the frame F _H which divides the subcarriers into groups G _L for the group G _H and the low-speed terminals for high-speed terminal, constituting a sub-carrier group G _H for high-speed terminal and varying the dispersion number of common pilots or the number common pilots in a frame F _L constituting a sub-carrier of the low-speed terminal for group G _L. That is, the sixth embodiment, by increasing a common pilot number of frames F _H constituting a fast sub-carrier terminal, or to increase the dispersion number of common pilots, a common frame F _L constituting a sub-carrier for slow terminal Reduce the number of pilots or reduce the number of common pilots distributed.
FIG. 24 shows a case where four users are frequency-multiplexed, assuming that two users are moving at low speed and the remaining two users are moving at high speed, and subcarriers used in OFDM are largely divided into two groups G _H and G _L. The high-speed terminal group _GH subcarriers are assigned to the first and second high-speed users, and the low-speed terminal group _GL subcarriers are assigned to the first and second low-speed users. In this case, the lower frequency is the high-speed movement group G _H and the higher frequency is the low-speed movement group G _L , but the reverse is also possible. In FIG. 24, pilots are arranged on all subcarriers, that is, arranged continuously in the frequency direction, but it is also possible to arrange pilots at regular intervals or at irregular intervals.
FIG. 25 shows an example of frequency division and frame configuration when the ratio of the number of terminals moving at low speed to the number of terminals moving at high speed is 3: 1.
FIG. 26 shows an example of frequency division and frame configuration when data is frequency-multiplexed to one terminal moving at a low speed and one terminal moving at a high speed.
FIG. 27 shows a configuration example of frequency division and frames when low-speed moving subcarriers and high-speed moving subcarriers are dispersed. Subcarriers are alternately allocated to high-speed users and low-speed users.

FIG. 28 is a block diagram of the base station BTS of the sixth embodiment, and the same components as those of the base station of the first embodiment of FIG. The difference is that (1) a group / subcarrier setting unit 80 is provided instead of the frame selection / setting unit 30, and (2) a frame F _H frame composed of subcarriers for high-speed terminals from the frame pattern generation unit 21. data of the frame pattern FLPN frame F _L constituting a pattern FHPN and subcarrier for the slow terminal that inputs to the mapping unit 23, (3) the mapping unit 23 toward the mobile terminal the sub-carriers allocated to the mobile terminal This is the point where data is transmitted by frequency-multiplexing and frequency multiplexing.
Frame pattern generator 21, as shown in FIGS. 24 to 26, the mapping unit 23 repeatedly generates a frame pattern FLPN frame pattern FHPN and the frame F _L of the frame F _H formed by inserting the pilot symbols in place, respectively input.
The transmission data processing unit 22 multiplexes, encodes, modulates data, and inputs the control data, user data, and other data (movement speed request data, subcarrier allocation data) to the mapping unit. The mapping unit 23 acquires the subcarrier assigned to the destination mobile station of the user data from the group / subcarrier setting unit 80, and maps the user data to the subcarrier. The OFDM transmission unit 24 performs IFFT processing on M (= n × N) subcarrier samples and combines them, inserts a guard interval GI into the combined time signal, and the wireless transmission unit 25 sets the frequency of the baseband signal. After up-converting to a radio frequency, it is amplified and transmitted from the antenna 26.
The radio receiving unit 27 down-converts the frequency of the radio signal received from the mobile station to the baseband frequency, and the demodulating unit 28 demodulates the baseband signal by applying demodulation processing. The reception data processing unit 29 performs error correction decoding processing on the demodulation result, and separates and outputs uplink transmission data, control data, and moving speed data from the user from the decoding result.
The group / subcarrier setting unit 80 includes a subcarrier determining unit 80a, a moving speed determining unit 80b, and a subcarrier holding unit 80c. The subcarrier determining unit 80a periodically requests the moving speed of each mobile station, and the moving speed determining unit 80b determines the moving speed V _EUi (i = 1, 2,...) Received from the mobile station and the threshold value Vth. Based on this, it is determined whether the mobile station is moving at high speed or low speed, and the determination result is input to the subcarrier determining unit 80a. The subcarrier determining unit 80a divides the mobile station into a low-speed terminal group and a high-speed terminal group based on the moving speed, determines a subcarrier used by the mobile station, and sets it in the subcarrier holding unit 80c. The mapping unit 23 identifies the subcarrier assigned to the destination mobile station of the downlink user data based on the content held in the subcarrier holding unit 80c, and maps the data to the subcarrier.
When the moving speed is requested from the subcarrier determining unit 80a, the transmission information creating unit 31 creates moving speed request data and transmits it to the mobile station via the transmission data processing unit 22. The transmission information creation unit 31 creates subcarrier setting data to transmit the subcarrier to the mobile station when the subcarrier determination unit 80a is instructed to notify the substation to be set to the mobile station. The data is transmitted to the mobile station via the unit 22.
As described above, according to the sixth embodiment, a plurality of subcarriers are divided into two groups, and the number of common pilots or the common pilots in a frame composed of the first group of subcarriers and a frame composed of the second group of subcarriers Since the data is mapped to each frame composed of the first and second groups of subcarriers and repeatedly transmitted to the mobile terminal, the pilot is transmitted using a fixed frame pattern. The number of symbols can be controlled.
The above description is a case where a plurality of subcarriers are divided into two groups, but the same control can be performed by dividing the subcarriers into three or more groups. That is, a plurality of subcarriers are divided into a plurality of groups, the number of common pilots or the number of common pilot dispersions in the frames composed of the subcarriers for each group is varied, and data is mapped to each frame and repeated mobile terminals. Can be configured to transmit to.

In summary, according to the present invention, the following effects are obtained:
・ Reception field strength measurement accuracy can be improved in both high-speed and low-speed movement states.
-Channel estimation accuracy can be improved in both high-speed and low-speed movement conditions.
・ Transmission speed and throughput can be improved.
-There is an effect that the transmission speed and throughput of the entire base station can be improved.
In the above embodiments, the case where the frame to be used is determined based on the moving speed has been described. However, the frame to be used is determined not only based on the moving speed but also based on the reception state such as the propagation environment, reception quality, and reception power. It can also be configured.
Further, although only two types of frame patterns FRPT shown in FIGS. 19 (a) and 19 (b) are shown, the present invention is not limited to these two types, and in general, at least the number of common pilots or the number of shared pilot dispersions is different from each other. A frame pattern formed by combining one or more of two types of frames can be employed.
In the embodiment, the case of performing communication using subcarriers has been described. However, the present invention can also be applied to the case of performing communication without using subcarriers.

・ Additional notes
(Appendix 1)
In a radio communication method of a radio base station that performs data communication with a mobile terminal,
At least two types of frames with different numbers of common pilots or at least two types of frames with different numbers of common pilots are combined in combination of one or more, data is mapped to each frame, and each set is repeatedly transmitted to the mobile terminal. ,
A wireless communication method.
(Appendix 2)
The number of common pilots in each type of frame and the arrangement pattern of the common pilots are different.
The wireless communication method according to supplementary note 1, wherein:
(Appendix 3)
In a radio base station, assign a frame with a large number of common pilots or a large number of dispersions to mobile terminals with poor reception quality, assign a frame with a small number of common pilots or a small number of dispersions to mobile terminals with good reception quality,
Notifying the allocated frame from the radio base station to the mobile terminal,
The wireless communication method according to supplementary note 1, wherein:
(Appendix 4)
Measuring the reception quality at the mobile terminal, determining a frame to be used by the radio base station for the mobile terminal based on the reception quality, and notifying the radio base station;
The radio base station maps and transmits data for the mobile terminal to the notified frame.
The wireless communication method according to supplementary note 1, wherein:
(Appendix 5)
The radio base station transmits data for a plurality of mobile terminals in each frame by frequency multiplexing, code multiplexing, or time division multiplexing.
The wireless communication method according to supplementary note 1, wherein:
(Appendix 6)
The mobile terminal performs reception quality measurement or channel estimation or reception power measurement using the common pilot of the frame for its own terminal.
The wireless communication method according to supplementary note 1, wherein:
(Appendix 7)
In the radio base station, the mobile terminals are grouped for each frame constituting the combination,
Perform transmission scheduling processing based on the reception quality measurement result reported from the mobile terminal for each group,
The wireless communication method according to appendix 5, wherein:
(Appendix 8)
Based on the reception quality of each mobile terminal that communicates with the radio base station, determine a combination of frames constituting the set and assign a mobile terminal to each frame;
Informing the mobile terminal of the determined combination of frames and the frame assigned to the mobile terminal;
The wireless communication method according to supplementary note 1, wherein:
(Appendix 9)
In a radio base station that performs data communication with a mobile terminal,
A frame pattern generator that repeatedly generates a frame pattern formed by combining one or more of at least two types of frames having different numbers of common pilots, or at least two types of frames having different numbers of shared pilots;
A data mapping unit that maps data to each frame;
A transmitter for transmitting the frame pattern to which data is mapped to a mobile terminal;
A radio base station comprising:
(Appendix 10)
The frame pattern generation unit generates a frame pattern in which the number of common pilots in each type of frame and the arrangement pattern of the common pilots are different.
The radio base station as set forth in appendix 9, wherein
(Appendix 11)
A frame setting unit that allocates a frame with a large number of common pilots to a mobile terminal with poor reception quality and allocates a frame with a small number of common pilots to a mobile terminal with good reception quality;
A frame setting information notification unit for notifying the mobile terminal of the allocated frame;
The frame pattern generation unit maps and transmits data for the mobile terminal to the frame,
The radio base station as set forth in appendix 9, wherein
(Appendix 12)
A receiving unit for receiving a frame used for the mobile terminal from the mobile terminal;
The frame pattern generation unit maps and transmits data for the mobile terminal to the frame,
The radio base station as set forth in appendix 9, wherein
(Appendix 13)
A multiplexing unit for frequency multiplexing or code multiplexing or time division multiplexing data for a plurality of mobile terminals in each frame is provided,
The transmitter transmits the multiplexed data;
The radio base station as set forth in appendix 9, wherein
(Appendix 14)
A receiving unit for receiving a reception quality measurement result in the mobile terminal;
A scheduler for performing transmission scheduling for each frame constituting the frame pattern based on a reception quality measurement result of the mobile terminal;
The radio base station according to supplementary note 13, comprising:
(Appendix 15)
15. The radio base station according to appendix 14, wherein the scheduler further includes a scheduler that performs the scheduling for each frame.
(Appendix 16)
A frame pattern determining unit that determines the frame pattern based on reception quality of a plurality of communicating mobile terminals in a cell and assigns the mobile terminal to each frame of the frame pattern;
A notification unit for notifying a mobile terminal of the determined frame pattern and a frame assigned to the mobile terminal;
The radio base station according to appendix 9, characterized by comprising:
(Appendix 17)
In a wireless communication method of a wireless base station that performs data communication using a plurality of subcarriers,
Dividing the plurality of subcarriers into a plurality of groups;
The number of common pilots or the number of common pilot dispersions in a frame composed of subcarriers for each group is changed.
Data is mapped to each frame and repeatedly transmitted to the mobile terminal.
A wireless communication method.
(Appendix 18)
In a radio base station, a subcarrier of a frame with a large number of common pilots or a large number of dispersion is allocated to a mobile terminal with poor reception quality, and a frame with a small number of common pilots or a small number of dispersion is allocated to a mobile terminal with good reception quality. Assign subcarriers,
Informing the mobile terminal of the allocated subcarrier from the radio base station,
The wireless communication method according to supplementary note 17, characterized by:
(Appendix 19)
The radio base station transmits data for a plurality of mobile terminals in each frame for each group by frequency multiplexing.
The wireless communication method according to supplementary note 17, characterized by:
(Appendix 20)
In a radio base station that performs data communication using a plurality of subcarriers,
A frame pattern generation unit that repeatedly generates a plurality of frame patterns having different numbers of common pilots or common pilots;
A data mapping unit that divides a plurality of subcarriers into a plurality of groups and maps data to frames configured by subcarriers of each group based on the generated frame patterns,
A transmission unit that transmits each frame to which data is mapped to a mobile terminal by frequency multiplexing;
A radio base station comprising:
(Appendix 21)
The data mapping unit allocates a subcarrier of a frame having a large number of common pilots or a large number of dispersions to a mobile terminal having poor reception quality, and a frame having a small number of common pilots or a small number of distributions to mobile terminals having good reception quality. 21. The radio base station according to appendix 20, wherein the subcarriers are allocated and data is mapped.

P, P ′ pilot symbol
Group for G _H high-speed terminals
G _L Group for low speed terminals
F _H group for high-speed terminals
F _L Low-speed terminal group frame

Claims (2)

In a mobile terminal that receives data transmitted from a radio base station using a plurality of subcarriers,
The plurality of subcarriers are divided into a plurality of groups with a certain number of subcarriers, and the number of common pilots or the number of common pilots distributed in a frame having a constant length in the time axis direction composed of subcarriers for each group is set. Different for each group, each frame having a fixed length in the time axis direction and the frequency axis direction is allocated to each mobile terminal, and data to be transmitted to each mobile terminal is transmitted to each frame having a fixed length allocated to the mobile terminal. A radio reception unit that performs mapping and receives a frame in which the data transmitted from a radio base station to a plurality of mobile terminals is mapped by frequency multiplexing ;
A mobile terminal comprising: In a mobile terminal that receives data transmitted from a radio base station using a plurality of subcarriers,
A frame pattern generation unit that repeatedly generates at least two types of frame patterns having a constant length in the time axis direction and the frequency axis direction, the number of common pilots or the number of common pilots being distributed, and a plurality of subcarriers in the frequency axis direction divided into a plurality of groups in a number of sub-carriers in the length of the generated time-axis direction composed of subcarriers for each group by using the respective frame pattern assigns a constant of each frame to each mobile terminal, A data mapping unit that maps data to be transmitted to each mobile terminal to each frame allocated to the mobile terminal; and a transmission unit that transmits each frame mapped with data to a plurality of mobile terminals by frequency multiplexing. Radio receiving unit for receiving a frame mapped with the data transmitted from another radio base station
A mobile terminal comprising:

Images