JP5083402B2 - base station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce interference between cells or between sectors. <P>SOLUTION: In a base station in a wireless communication system using a pilot signal having a predetermined pattern during transmission from a user terminal to a base station, a storage section stores a pilot pattern which is set in such a way that pilot patterns used in neighboring base stations or neighboring sectors become different and pilot patterns in the same base station or the same sector become different for each modulation scheme, a pilot pattern assignment section refers to a corresponding relationship between the modulation scheme and a pilot to assign a pilot pattern corresponding to the modulation scheme of the user terminal to the user terminal, and a pilot pattern notification section notifies the user terminal of the pilot pattern corresponding to the modulation scheme. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a base station, and more particularly to a base station in a wireless communication system that uses a pilot signal having a predetermined pilot pattern when transmitting from a user terminal to the base station.

In a wireless communication system such as a cellular system, synchronization or channel estimation is performed using a known pilot signal, and data is demodulated. When adaptive modulation is used, a pilot signal is also used when performing signal-to-interference (noise) power ratio (SIR) estimation to determine an optimal modulation method.
In the uplink from the user terminal to the base station, a pilot pattern with good correlation characteristics is used as a pilot signal in order to suppress interference from other users and multipath interference.

FIG. 27 is an uplink frame configuration diagram standardized by 3GPP. Dedicated Physical Data Channel (DPDCH) in which only transmission data is transmitted, and control data such as pilot pilot and TPC bit information are multiplexed. In this case, each of them is transmitted after being spread by an orthogonal code. One uplink frame is 10 msec, and is composed of 15 slots (slot # 0 to slot # 14). Each slot of the dedicated control channel DPCCH is composed of 10 bits, the symbol rate is constant at 15 ksps, and a pilot pilot, transmission power control data TPC, transport format combination indicator TFCI, and feedback information FBI are transmitted. FIG. 28A shows a pilot pattern of slot numbers Slot # 0 to # 14 when the number of pilot bits in DPCCH is 3, 4, 5 and 6, and FIG. 28B shows a case where the number of pilot bits is 7 and 8. This is a pilot pattern of slot numbers Slot # 0 to # 14. In this case, if the number of pilot bits is the same, the pattern of the pilot signal will be the same, but since different pilots and data are collectively multiplied by different scramble codes having a small cross-correlation, The transmitted pilot patterns are different sequences having a small cross-correlation with each other (see Non-Patent Document 1).
Conventionally, a pilot pattern of a sequence in which the peak-to-average power characteristic does not change greatly depending on the sequence number even when multiplied by the Gold code used in the above scramble code has been applied. Therefore, an arbitrary pilot pattern could be assigned to the user terminal.

In recent years, OFDM (Orthogonal Frequency Division Multiplex), IFDMA (Interleaved Frequency Division Multiple Access), DFT-S-OFDM (Discrete Fourier Transform-Spread- Orthogonal Frequency Division Multiplex), etc. that perform all or part of channel estimation processing in the frequency domain With the development of modulation schemes, CAZAC (Constant Amplitude Zero Auto Correlation) sequences or GCL (Generalized Chirp Like) sequences are attracting attention as sequences applied to pilot patterns. As an example of the CAZAC sequence, the calculation formula of the Zadoff-Chu sequence is shown below (see Non-Patent Document 2).

Here, n is a symbol number. If the integers k and L are relatively prime, the sequence length of the sequence Ck (n) with the sequence number k is L, and n = 1 to L. Further, k ≦ L−1.

The CAZAC sequence has zero autocorrelation with respect to cyclic shift, and has a characteristic of maintaining constant amplitude in both the time domain and the frequency domain, so it attracts attention as a pilot signal, and is proposed as an uplink pilot pattern in 3GPP ( Non-patent document 3).
However, in the CAZAC sequence, the peak-to-average power ratio PAPR varies greatly depending on the sequence number k. For this reason, if it assigns to each terminal arbitrarily like the past, the terminal where reception quality falls will appear. For example, if a sequence that has a poor peak-to-average power characteristic PAPR is assigned to a terminal that needs to transmit at the maximum transmission power, the peak power of the transmission signal increases and peak suppression is performed, resulting in distortion and transmission. The characteristics will deteriorate. Hereinafter, this point will be described in detail.
As the output power of the amplifier used in the transmitter is larger, the power added efficiency is improved. For this reason, it is desirable to make the operating point as close as possible to the maximum value of the output power. However, when the output power exceeds a certain threshold value, nonlinear distortion that is unacceptable for a transmission signal occurs, so there is a trade-off between distortion and power added efficiency. The better the peak-to-average power characteristic of the transmission signal, the smaller the difference (backoff) between the operating point and the threshold value, and the power added efficiency can be improved.

  FIG. 29 is an example of the AM-AM characteristic (input power / gain characteristic) of the amplifier for explaining the back-off. The amplifier has a flat gain characteristic and a linear input / output characteristic when the input power is small. However, when the input power exceeds a certain level, the gain begins to decrease and a phase delay occurs, resulting in non-linearity. The output power level with the gain reduced by 1 dB is referred to as a 1 dB compression level, and the difference between the level and the average output power Pmean is the back-off OBO. In such a nonlinear amplifier, even if the average power level of the input signal exists in the linear part, the signal at or near the maximum power level exceeds the 1 dB compression level due to the balance between the back-off OBO and the peak-to-average power ratio PAPR. Will be distorted. Therefore, considering the peak-to-average power ratio PAPR, the back-off OBO is determined so as not to exceed the 1 dB compression level when the input signal of the maximum power level arrives. That is, if the peak-to-average power ratio PAPR is small, the back-off OBO can be reduced and the power added efficiency of the amplifier can be improved. However, if the peak-to-average power ratio PAPR is large, the back-off OBO increases and the power added efficiency of the amplifier decreases.

Now, the peak-to-average power ratio PAPR has been often used to express the power derating of the amplifier with respect to the signal power, but it is defined by the following equation (2) as a more accurate representation of the power derating. Recently, an evaluation index called Cubic Metric (CM) has been used (Non-patent Document 4). In this specification, evaluation indexes such as PAPR and Cubic Metric are collectively expressed using the expression peak-to-average power characteristics.

Here, v_norm is the normalized amplitude value of the input signal, and v_norm_ref is the amplitude value of the reference signal. A signal with a larger CM has a worse peak-to-average power characteristic, requires a larger back-off, and lowers power added efficiency.
The CM characteristics of the Zadoff-Chu sequence having sequence length 127 and sequence length 37 are as shown in FIG. For reference, a CM when a random sequence is modulated with π / 2-BPSK, QPSK, and 16QAM is also shown. As can be seen from FIG. 30, some CAZAC sequences show better CM characteristics than π / 2-BPSK depending on the sequence number k, and others show CM characteristics worse than 16QAM.

In this way, when a sequence having a very large variation in CM characteristics is used as an uplink pilot signal, the back-off design of the amplifier of the user terminal becomes a problem. If the back-off of the amplifier of the user terminal is designed to be large in accordance with the worst value of the CM characteristic, distortion will not occur regardless of the CM characteristic, but the average power added efficiency will deteriorate. On the other hand, if the amplifier back-off is designed to match the average value, when transmitting at the maximum or near transmit power, the pilot pattern with poor CM characteristics will exceed the 1 dB compression level, resulting in distortion and transmission efficiency degradation. To do.
From the above, when applying a sequence that is suitable for channel estimation but has a large variation in peak-to-average power characteristics (for example, CAZAC sequence) to an uplink pilot signal, how to assign a pilot pattern to each user terminal Is the problem. When a pilot pattern is arbitrarily assigned to each user regardless of the peak-to-average power characteristic as in the conventional case, the signal waveform of the user terminal that transmits with high power is affected by the assigned pilot pattern, and in some cases, a large distortion is caused. Will occur.

3GPP TS25.211 (Pilot signal specification part) and TS25.213 (Scramble code specification part): http://www.3gpp.org/ D.C. Chu, "Polyphase Codes With Good Periodic Correlation Properties", IEEE Transactions on Information Theory.pp 531-532, July 1972 3GPP TR25.814: http://www.3gpp.org/ TSG RAN WG1 # 37, Montreal, Canada, May 10-14, 2004: Tdoc # R 1-040642

As described above, an object of the present invention is to prevent distortion from occurring in a transmission amplifier of a user terminal even when the user terminal uses a sequence having a large variation in peak-to-average power characteristics as a pilot pattern. It is to improve the reception quality in.
Another object of the present invention is to prevent distortion from occurring in a transmission amplifier even when a user terminal performs transmission at or near the maximum transmission power.
Another object of the present invention is to prevent distortion even when the back-off of the transmission amplifier is reduced, thereby improving the average power added efficiency and extending the battery duration of the user terminal. .
Another object of the present invention is to reduce interference between cells or sectors.

The present invention is a base station in a radio communication system using a pilot signal having a pilot pattern of a predetermined CAZAC sequence at the time of transmission from a user terminal to the base station, and a CAZAC sequence pilot used in an adjacent base station or an adjacent sector CAZAC sequences according to the use of the user terminal based on the correspondence between the use and pilot pattern, with different patterns and the CAZAC sequence pilot pattern in the same base station or the same sector set for each use A pilot pattern allocating unit for allocating the pilot pattern to the user terminal, and a pilot pattern notifying unit for notifying the user terminal of the pilot pattern of the CAZAC sequence corresponding to the application.
In the base station in the above wireless communication system, the application is a modulation method, and the pilot pattern is set so that the pilot pattern of the CAZAC sequence in the same base station or the same sector differs for each modulation method.
In the base station in the wireless communication system, a CAZAC sequence pilot pattern is set for each data transmission interval and non-data transmission interval and for each modulation scheme, and the pilot pattern allocating unit is for data transmission intervals and non-data A CAAZAC sequence pilot pattern is assigned to a user terminal in a manner distinct from that for a transmission interval.
In the base station in the above wireless communication system, the number of pilot patterns of CAZAC sequences used for the assignment is set differently for each modulation scheme.

  According to the present invention, even when a user terminal uses a sequence having a large variation in peak-to-average power characteristics as a pilot pattern, distortion can be prevented from occurring in the transmission amplifier of the user terminal, and reception quality at the base station can be reduced. Can be improved. Further, according to the present invention, even when the user terminal transmits at maximum or close to the transmission power, distortion can be prevented from occurring in the transmission amplifier. Further, according to the present invention, distortion can be prevented even if the back-off of the transmission amplifier is reduced, and as a result, the average power addition efficiency can be improved and the battery duration of the user terminal can be increased. . Moreover, according to the present invention, interference between cells or sectors can be reduced.

It is a block diagram of the base station of 1st Example. It is a block diagram of the base station in 2nd Example. It is signal format explanatory drawing. It is explanatory drawing of a pilot pattern management table. It is a block diagram of the user terminal in 2nd Example. It is a block diagram of the base station in 3rd Example. It is a block diagram of the user terminal in 3rd Example. It is a block diagram of the base station of a 1st modification. It is a block diagram of the user terminal in a 1st modification. It is a block diagram of the base station of a 2nd modification. It is a block diagram of the user terminal in a 2nd modification. It is a block diagram of the base station of a 3rd modification. It is a block diagram of the base station in 4th Example. It is a block diagram of the base station of 5th Example. It is a block diagram of the base station of 6th Example. It is a block diagram of the user terminal of 6th Example. 5 is a table showing the number of divisions and the number of pilot patterns that can be used for each modulation method when 5 MHz is used after frequency division by a plurality of user terminals. It is a block diagram of the base station of 7th Example. It is a figure explaining the sequence number of the pilot pattern which can be used for a π / 2-BPSK modulation system and a QPSK modulation system when each pilot pattern of a CAZAC sequence of a predetermined length is ranked based on peak-to-average power characteristics. It is explanatory drawing of the pilot pattern allocated to each cell BS1-BS7 in a hexagonal cell arrangement | positioning. It is a pilot pattern management table when the pilot pattern sequence number of each modulation system is set for a plurality of sequence lengths. In a hexagonal cell arrangement, it is an explanatory diagram in the case of assigning one or more pilot patterns to each cell BS1 to BS7 for each modulation scheme. It is a block diagram of the user terminal of 7th Example. This is a specific pilot pattern setting example when the number of pilot patterns (number of repetitions) that can be used in each modulation scheme is three. 21 is an example of a pilot pattern assigned to each cell (base station) when the hexagonal cell arrangement of FIG. 20 is further expanded. It is an example of a pilot pattern management table TBL considering a pilot pattern in a non-data transmission section. FIG. 3 is an uplink frame configuration diagram standardized by 3GPP. This is a pilot pattern of pilot slot numbers Slot # 0 to # 14 in DPCCH. It is an example of the AM-AM characteristic (input power / gain characteristic) of the amplifier for demonstrating backoff. This is a CM characteristic of a Zadoff-Chu sequence with sequence length 127 and sequence length 37.

(A) First Embodiment FIG. 1 is a configuration diagram of a base station according to a first embodiment. The base station 1 stores a rank table for peak-to-average power characteristics of each pilot pattern, and When establishing a connection between them, a pilot pattern is assigned to the user terminal 2 in order of good peak-to-average power characteristics.
The radio 11 includes a transmitter and a receiver, and the receiver converts the received signal from a radio frequency to a baseband frequency and inputs it to the upstream signal baseband processing unit 12. The baseband processing unit 12 separates and demodulates user data and control data from the input signal, and inputs the control data to the uplink control unit 13. The uplink control unit 13 requests the pilot pattern allocation unit 14 to allocate a pilot pattern using the signal PRQ when setting a connection.
When the storage unit 15 ranks the pilot patterns of the CAZAC sequence based on the peak-to-average power characteristics, the storage unit 15 lists the sequence number k, used / unused, and assigned user terminal ID in order from the best. The ranking table (pilot pattern management table TBL) is held. When the pilot pattern allocation unit 14 receives the pilot pattern allocation request PRQ from the uplink control unit 13, the pilot pattern allocation unit 14 refers to the pilot pattern management table TBL and sets the sequence numbers PAL of unused pilot patterns in order of good peak-to-average power characteristics. Notify the uplink control unit 13. Further, the pilot pattern assignment unit 14 enters “YES” in the in-use field of the assigned pilot pattern sequence number, and also fills in the user terminal ID assigned in the user terminal field.
The downlink signal baseband processing unit 16 encodes the user data and the pilot pattern sequence number, and then modulates and multiplexes them and inputs them to the transmitter of the radio 11. The transmitter frequency-converts the baseband signal into a radio frequency, amplifies it, and transmits it to the user terminal 2. The user terminal 2 demodulates the pilot pattern sequence number from the received signal, thereafter generates a pilot pattern of the sequence number, multiplexes the pilot, user data, and control data and transmits them to the base station.
The above is the operation at the time of connection setting. When the connection is released, the pilot pattern assignment unit 14 enters “NO” in the in-use field of the pilot pattern assigned to the user terminal that released the connection, and the user terminal Enter a blank in the field.
According to the first embodiment, since the pilot sequences are assigned in order from the one with the best peak-to-average power characteristics, the user terminal is more likely to use the pilot signal with the good peak-to-average power characteristics. As a result, even when the transmission power is high, distortion can be prevented from occurring in the transmission amplifier of the user terminal, and reception quality at the base station can be improved.

(B) Second Embodiment FIG. 2 is a block diagram of a base station in the second embodiment. In the second embodiment, the pilot pattern is determined based on the transmission power of the user terminal.
Although not shown, the radio 21 includes a transmitter and a receiver, and the receiver converts the received signal from a radio frequency to a baseband frequency and inputs it to the upstream signal baseband processing unit 22. The signal format is composed of, for example, a pilot PL, control information CNT, user data DT, and error detection CRC as shown in FIG.
The separation unit 22a of the baseband processing unit 22 separates pilot, user data, and control data from the input signal, the channel estimation unit 22b estimates a channel (propagation characteristic) using the pilot signal, and the demodulation unit 22c performs channel estimation. After channel compensation based on the value, demodulation processing is performed, and the decoding unit 22d performs error correction decoding processing and outputs user data. Further, the demodulator 22e performs channel compensation based on the channel estimation value and then performs demodulation processing, and the decoding unit 22f performs error correction decoding processing and outputs control information. This control information includes transmission power level of the user terminal or difference power information between the maximum transmission power level and the actual transmission power level.

The ranking unit 23a of the pilot pattern management unit 23 ranks based on the transmission power level (or difference power) of the user terminals included in the control information. For example, if there are three classes A, B, and C in descending order of transmission power level, the class to which the transmission power level of the user terminal belongs is determined and input to the pilot pattern allocation unit 23b.
When the storage unit 23c ranks the pilot patterns of the CAZAC sequence based on the peak-to-average power characteristic, the storage unit 23c lists the sequence number k, used / unused, and assigned user terminal ID in order from the best. The ranking table (pilot pattern management table TBL) is held (see FIG. 4). In this table TBL, as shown in FIG. 4, the sequence numbers k are classified into three classes A, B, and C from a good one. Note that the number of classes is not limited to three, and may be two or four or more.
When the pilot pattern allocation unit 23b receives the class of the transmission power level of the user terminal from the ranking unit 23a, the pilot pattern allocation unit 23b refers to the class in the pilot pattern management table TBL that is the same as the class of the transmission power level, and the peak-to-average in the class A sequence number of an unused pilot pattern is obtained in the order of good power characteristics, and the sequence number of the pilot pattern is input to the downlink signal baseband processing unit 24. Further, the pilot pattern assignment unit 23b enters “YES” in the in-use information field of the assigned pilot pattern sequence number, and enters the user terminal ID to which the pilot pattern is assigned in the user terminal field.

The uplink control unit 25 determines the modulation scheme and coding rate of the user terminal based on the channel estimation value, the transmission power level of the user terminal, etc., and creates a TFC (Transport Format Combination) based on these to create the downlink signal baseband Input to the processing unit 24. The upstream power control unit 26 performs well-known upstream power control to create power control information and inputs the power control information to the downstream signal baseband processing unit 24. Uplink power control measures the SIR using a received pilot signal, creates power control information for controlling the transmission power of the user terminal so that the SIR becomes the target SIR, transmits the power control information to the user terminal, and the user terminal This is control for determining the transmission power level using the power control information.
The downlink signal baseband processing unit 24 encodes the user data, the pilot pattern sequence number, the power control information, and the TFC, and then modulates and multiplexes them to input to the transmitter of the radio 21. The transmitter frequency-converts the baseband signal to a radio frequency, amplifies it, and transmits it to the user terminal. The user terminal demodulates the pilot pattern sequence number from the received signal, thereafter generates a pilot pattern of the sequence number, multiplexes the pilot, user data, and control data and transmits them to the base station. Further, the user terminal determines the transmission power level based on the power control information.

FIG. 5 is a block diagram of a user terminal in the second embodiment. The receiver of the radio device 31 converts the received signal from a radio frequency to a baseband frequency and inputs it to the downlink signal baseband processing unit 32.
The baseband processing unit 32 separates user data, pilot sequence numbers, and control data (power control information, TFC information) from the input signal, and the pilot pattern generation unit 33 generates a pilot signal based on the input pilot sequence number. . The transmission power determination unit 34 determines and outputs a transmission power level and an amplitude coefficient based on the power control information, and the control information creation unit 35 creates and outputs control information including the transmission power level and other information. The transmission signal control unit 36 inputs the modulation scheme and coding rate included in the TFC information to the modulation units 37a and 37b and the coding units 38a and 38b, respectively. The encoding units 38a and 38b encode user data and control information with the input encoding method and encoding rate, and the modulation units 37a and 37b modulate the input data with the input modulation method, and the power control / multiplexing unit Reference numeral 39 multiplies user data, control information, and a pilot signal by an amplitude coefficient to perform power control, and then multiplexes them and inputs them to the transmitter of the radio 31. The transmitter frequency-converts the baseband signal to a radio frequency, amplifies it, and transmits it to the base station.
When the transmission power level of the user terminal changes and the class of the transmission power level changes, the base station controls to cancel the previous assignment and assign the pilot pattern in the new class.

In the above, the transmission power determination unit 34 determines the transmission power level based on the power control information from the base station, but it can also be determined by another method. For example, the transmission power level can be gradually increased at the user terminal, control information indicating the transmission power level OK can be received from the base station, and the transmission power level at that time can be notified to the base station.
Moreover, although the case where a pilot pattern with good peak-to-average power characteristics is assigned to a user terminal with high transmission power has been described above, a difference from the maximum transmission power is transmitted from the user terminal to the base station, It is also possible to perform control so that a pilot pattern with good peak-to-average power characteristics is assigned to a user terminal with a small difference.
As described above, according to the second embodiment, even when a user terminal uses a sequence having a large variation in peak-to-average power characteristics as a pilot pattern, distortion is not generated in the transmission amplifier of the user terminal. And the reception quality at the base station can be improved.
In addition, according to the second embodiment, since a pilot having good peak-to-average power characteristics is allocated to a user terminal having a large transmission power, even if the user terminal transmits at a maximum or near transmission power, the transmission amplifier Distortion can be prevented.
In addition, according to the second embodiment, distortion can be prevented even if the back-off of the transmission amplifier is reduced. As a result, the average power addition efficiency is improved and the battery duration of the user terminal is increased. Can do.

(C) Third Embodiment FIG. 6 is a block diagram of a base station in the third embodiment, and the same reference numerals are given to the same parts as in the second embodiment of FIG.
Since the transmission power of the user terminal increases as the distance from the base station increases, in the third embodiment, the pilot pattern is determined based on the position information of the user terminal (distance from the base station).
The receiver of the radio device 21 converts the received signal from a radio frequency to a baseband frequency and inputs it to the upstream signal baseband processing unit 22. The baseband processing unit 22 separates pilot, user data, and control data from the input signal, and inputs the control information to the terminal information processing unit 27. The terminal information processing unit 27 extracts the position information of the user terminal from the input control information and inputs it to the pilot pattern management unit 23.

The ranking unit 23a of the pilot pattern management unit 23 calculates the distance between the user terminal position and the base station position (known), divides the distance by the cell radius, normalizes, and based on the normalized distance Make a ranking. For example, if there are three classes A, B, and C in ascending order of the normalized distance, the class to which the normalized distance of the user terminal belongs is determined and input to the pilot pattern assignment unit 23b.
The storage unit 23c holds a rank table (pilot pattern management table TBL) as shown in FIG.
When the pilot pattern allocating unit 23b receives the class corresponding to the normalized distance of the user terminal from the ranking unit 23a, the pilot pattern allocating unit 23b refers to the class in the same pilot pattern management table as the normalized distance class, and the peak-to-average in the class A sequence number of an unused pilot pattern is obtained in the order of good power characteristics, and the sequence number of the pilot pattern is input to the downlink signal baseband processing unit 24. Further, the pilot pattern assigning unit 23b enters “YES” in the in-use information field of the assigned pilot pattern sequence number, and enters the user terminal ID to which the pilot pattern is assigned in the user terminal field.
The downlink signal baseband processing unit 24 encodes control information including user data and a pilot pattern sequence number, and then modulates and multiplexes the control information and inputs it to the transmitter of the radio 21. The transmitter frequency-converts the baseband signal to a radio frequency, amplifies it, and transmits it to the user terminal.
The user terminal demodulates the pilot pattern sequence number from the received signal, and thereafter generates a pilot pattern of the sequence number.

FIG. 7 is a block diagram of the user terminal in the third embodiment, and the same reference numerals are given to the same parts as those in the second embodiment of FIG.
The receiver of the radio device 31 converts the received signal from a radio frequency to a baseband frequency and inputs it to the downlink signal baseband processing unit 32. The baseband processing unit 32 separates control data including user data and pilot sequence numbers from the input signal, and the pilot pattern generation unit 33 generates a pilot signal based on the input pilot sequence number.
The GPS receiver 41 measures the position (longitude and latitude) of the user terminal, and the control information creation unit 35 creates and outputs control information including the position information. Encoding units 38a and 38b encode user data and control information with a predetermined encoding method and coding rate, modulation units 37a and 37b modulate input data with a predetermined modulation method, and power control / multiplexing unit 39 After power control is performed by multiplying user data, control information, and pilot signals by an amplitude coefficient determined by a transmission power control unit (not shown), they are multiplexed and input to the transmitter of the radio 31. The transmitter frequency-converts the baseband signal to a radio frequency, amplifies it, and transmits it to the base station.
When the position of the user terminal changes and the normalized distance class changes, the base station performs control so that the previous pilot pattern assignment is deleted and the pilot pattern in the new class is assigned.

In the above, the pilot pattern sequence number is assigned based on the distance between the user terminal and the base station, but it can also be assigned based on the SIR. That is, the SIR is measured using a pilot signal transmitted by the user terminal, and based on the SIR, it is estimated whether the user terminal exists at the cell edge or the cell center, and the user terminal existing at the cell edge Assign a pilot pattern with good peak-to-average power characteristics.
According to the third embodiment, pilots having good peak-to-average power characteristics are allocated to user terminals having a large distance from the base station, so that the distance increases and the user terminals transmit with maximum or close transmission power. Even in this case, distortion can be prevented from occurring in the transmission amplifier. Further, according to the third embodiment, an effect equivalent to that of the second embodiment can be achieved.

First Modification In the third embodiment, the pilot pattern is determined based on the position information of the user terminal. However, pilot information is used in the same manner as in the third embodiment using information on the propagation path condition (CQI: Channel Quality Indicator). The pattern can be determined. That is, if the propagation path condition is good, the transmission power is low, and if the propagation path condition is bad, the transmission power is large. Therefore, in the first modification, the pilot pattern is determined based on the CQI.
FIG. 8 is a block diagram of the base station in such a case, which is substantially the same as FIG. 6, except that the terminal information processing unit 27 extracts CQI from control information sent from the user terminal, based on the CQI. The pilot pattern is determined.
The terminal information processing unit 27 extracts the channel quality display CQI of the user terminal from the input control information and inputs it to the pilot pattern management unit 23. The ranking unit 23a of the pilot pattern management unit 23 ranks based on the input CQI. For example, if there are three classes A, B, and C in descending order of CQI, the class to which the CQI of the user terminal belongs is determined and input to the pilot pattern assignment unit 23b. When the pilot pattern allocation unit 23b receives the CQI class of the user terminal, the pilot pattern allocation unit 23b refers to the class in the pilot pattern management table TBL that is the same as the CQI class, and uses the unused pilot pattern in order of good peak-to-average power characteristics in the class. The pilot pattern sequence number is input to the downlink signal baseband processing unit 24 and transmitted to the user terminal. The user terminal demodulates the pilot pattern sequence number from the received signal, and thereafter generates a pilot pattern of the sequence number.

FIG. 9 is a block diagram of the user terminal in the first modification, and the same reference numerals are given to the same parts as those in the third embodiment of FIG. The difference is that a CQI output unit 42 is provided instead of the GPS receiver.
The receiver of the radio device 31 converts the received signal from a radio frequency to a baseband frequency and inputs it to the downlink signal baseband processing unit 32. The baseband processing unit 32 separates user data, pilot sequence numbers, and common pilot CPI from the input signal, and the pilot pattern generation unit 33 generates a pilot signal based on the input pilot sequence number.
The SIR measurement unit 42a of the CQI output unit 42 measures SIR using the common pilot CPI, and the CQI generation unit 42b generates CQI using the SIR-CQI correspondence table 42c. The control information creation unit 35 creates and outputs control information including CQI. Thereafter, the user terminal operates in the same manner as in the third embodiment, and notifies the base station of the CQI.
When the CQI of the user terminal changes and the CQI class changes, the base station controls to delete the pilot pattern assignment so far and assign the pilot pattern in the new class.
According to the first modification, since a pilot with good peak-to-average power characteristics is assigned to a user terminal having a small CQI, the propagation path condition is deteriorated, and the user terminal transmits with maximum or near transmission power. However, distortion can be prevented from occurring in the transmission amplifier.

Second Modification FIG. 10 is a configuration diagram of a base station according to a second modification. There is no problem even if the pilot peak-to-average power characteristic in a section in which data is not transmitted (non-data transmission section) is worse than the pilot peak-to-average power characteristic in a section in which data is transmitted (data transmission section). Therefore, as shown in FIG. 10, the pilot sequences are classified into two classes, class A and class B, which have good peak-to-average power characteristics, class A pilots are assigned as pilots for data transmission sections, and pilots for non-data transmission sections Assign a class B pilot as
The configuration of the base station of FIG. 10 is substantially the same as that of the base station of the third embodiment of FIG. 6 except that the terminal information processing unit 27 determines the data transmission interval / non-data transmission from the control information sent from the user terminal. The point is that the section information is extracted, and the pilot pattern is determined based on the data transmission section / non-data transmission section.
The terminal information processing unit 27 extracts the data transmission section / non-data transmission section information of the user terminal from the input control information and inputs it to the pilot pattern management unit 23. The ranking unit 23a of the pilot pattern management unit 23 ranks based on the input data transmission interval / non-data transmission interval information. For example, the class is input to the pilot pattern allocating unit 23b as class A in the data transmission period and class B in the non-data transmission period. When the pilot pattern allocation unit 23b receives a class corresponding to the data transmission interval / non-data transmission interval of the user terminal, the pilot pattern allocation unit 23b refers to the class in the same pilot pattern management table as the class, and the peak-to-average power characteristic of the class is determined. A sequence number of an unused pilot pattern is obtained from a good order, and the sequence number of the pilot pattern is input to the downlink signal baseband processing unit 24 and transmitted to the user terminal.
The user terminal demodulates the pilot pattern sequence number from the received signal, and thereafter generates a pilot pattern of the sequence number.

FIG. 11 is a block diagram of the user terminal in the second modification, and the same reference numerals are given to the same parts as those in the third embodiment of FIG. The difference is that a data transmission section / non-data transmission section information generating unit 43 is provided instead of the GPS receiver.
The receiver of the radio device 31 converts the received signal from a radio frequency to a baseband frequency and inputs it to the downlink signal baseband processing unit 32. The baseband processing unit 32 separates user data and pilot sequence numbers from the input signal, and the pilot pattern generation unit 33 generates a pilot signal based on the input pilot sequence number.
The data transmission interval / non-data transmission interval information generation unit 43 generates data transmission interval / non-data transmission interval information, and the control information creation unit 35 creates and outputs control information including the information. Thereafter, the user terminal operates in the same manner as in the third embodiment, and notifies the base station of data transmission interval / non-data transmission interval information.
If the class changes due to a change in the data transmission section / non-data transmission section information of the user terminal, the base station performs control so as to cancel the pilot pattern assignment so far and assign the pilot pattern in the new class.
In the above description, the pilot pattern is assigned based on the data transmission interval / non-data transmission interval. However, the assignment can be determined according to the content of the uplink data. For example, the data that requires real-time performance in the ranking unit 23a is class A, and the data that is not required is class B, and the pilot pattern allocating unit 23b refers to the same pilot pattern management table class as the terminal class. It is also possible to assign a pattern.

Third Modification FIG. 12 is a block diagram of a base station according to a third modification. The same reference numerals are given to the same parts as those of the base station according to the third embodiment in FIG. In the third modified example, when the user terminal is classified based on UE Capability (communication capability such as transmission rate and available service), a pilot pattern is allocated to the user terminal using the classification.
At the time of connection setting, the terminal information processing unit 27 acquires the UE capability (communication capability) of the user terminal and inputs it to the pilot pattern management unit 23. The ranking unit 23a of the pilot pattern management unit 23 determines the class of the user terminal based on the communication capability, and inputs the class to the pilot pattern allocation unit 23b. For example, the user terminal having a higher required quality of service (QoS) has a higher class. When receiving the class of the user terminal, the pilot pattern allocation unit 23b refers to the class in the same pilot pattern management table TBL as that class, and obtains the sequence number of the unused pilot pattern in the order of good peak-to-average power characteristics. The sequence number of the pilot pattern is input to the downlink signal baseband processing unit 24 and transmitted to the user terminal.
The user terminal demodulates the pilot pattern sequence number from the received signal, and thereafter generates a pilot pattern of the sequence number.
According to the third modification, a pilot having good peak-to-average power characteristics can be allocated to a user terminal having a higher service class and higher transmission power. As a result, distortion occurs in the transmission amplifier of the user terminal. I can not.

(D) Fourth Embodiment FIG. 13 is a block diagram of a base station in the fourth embodiment, and the same reference numerals are given to the same parts as those in the second embodiment of FIG. In the fourth embodiment, the pilot pattern is determined based on the modulation scheme of the user terminal. A modulation scheme having a higher transmission rate requires a larger transmission power. Therefore, in the fourth embodiment, a pilot pattern having a good peak-to-average power characteristic is preferentially assigned to a user communicating with a modulation method having a high transmission rate.
The receiver of the radio device 21 converts the received signal from a radio frequency to a baseband frequency and inputs it to the upstream signal baseband processing unit 22. The separation unit 22a of the baseband processing unit 22 separates pilot, user data, and control data from the input signal, the channel estimation unit 22b estimates a channel (propagation characteristic) using the pilot signal, and the demodulation unit 22c performs channel estimation. After channel compensation based on the value, demodulation processing is performed, and the decoding unit 22d performs error correction decoding processing and outputs user data. Further, the demodulator 22e performs channel compensation based on the channel estimation value and then performs demodulation processing, and the decoding unit 22f performs error correction decoding processing and outputs control information. This control information includes CQI and position information of the user terminal.
The uplink control unit 25 determines the modulation scheme and coding rate of the user terminal based on the channel estimation value, CQI, etc., and creates a TFC (Transport Format Combination) based on these and inputs it to the downlink signal baseband processing unit 24 To do.

The ranking unit 23a of the pilot pattern management unit 23 ranks based on the modulation scheme included in the TFC. For example, if the modulation method is 16QAM, it is class A, if it is 8PSK, it is class B, and if it is QPSK, it is class C, and the class is input to the pilot pattern allocation unit 23b. The storage unit 23c holds a pilot pattern management table TBL (see FIG. 4), and classifies the sequence numbers k into the three classes A, B, and C from the best. When the pilot pattern allocating unit 23b receives the class from the ranking unit 23a, the pilot pattern allocating unit 23b refers to the class in the pilot pattern management table TBL that is the same as the class, obtains an unused pilot pattern in order of good peak-to-average power characteristics, The pilot pattern sequence number is input to the downlink signal baseband processing unit 24.
The downlink signal baseband processing unit 24 encodes the user data, the pilot pattern sequence number, and the TFC, and then modulates and multiplexes them to input to the transmitter of the radio device 21. The transmitter frequency-converts the baseband signal to a radio frequency, amplifies it, and transmits it to the user terminal.
As described above, according to the fourth embodiment, since a pilot having a good peak-to-average power characteristic is assigned to a user terminal having a high data transmission rate and a large transmission power, it is possible to prevent distortion in the transmission amplifier.

(E) Fifth Embodiment FIG. 14 is a block diagram of a base station according to the fifth embodiment, and the same components as those in FIG.
As the distance from the base station increases, the transmission power of the user terminal increases. However, even if the distance is the same, the transmission power of the user terminal changes depending on the situation of the propagation path and the modulation method. Therefore, the fifth embodiment determines the pilot pattern of the user terminal based on information on the propagation path such as CQI, the modulation scheme of the user terminal, and the position information of the user terminal.
The receiver of the radio device 21 converts the received signal from a radio frequency to a baseband frequency and inputs it to the upstream signal baseband processing unit 22. The baseband processing unit 22 performs the same operation as in FIG. 13 and outputs user data, channel estimation values, and control information. This control information includes CQI and position information of the user terminal.

The uplink control unit 25 determines the modulation scheme, coding rate, etc. of the user terminal based on the channel estimation value, CQI, etc., and creates a TFC (Transport Format Combination) based on these, and inputs it to the downlink signal baseband processing unit 24 To do.
The ranking unit 23a of the pilot pattern management unit 23 ranks based on the CQI of user terminals included in the control information, the position information, and the modulation scheme included in the TFC. For example, the position information after normalization of the user terminal x is l (x), the propagation path information is p (x), and the modulation information is m (x).

That is, if there are three classes A, B, and C in descending order of the calculation result of the above equation, the ranking unit 23a calculates f (x) of the user terminal and determines the class to which the calculation result belongs. To the pilot pattern assignment unit 23b. The storage unit 23c holds a pilot pattern management table TBL (see FIG. 4), and classifies the sequence numbers k into the three classes A, B, and C from the best. When the pilot pattern allocating unit 23b receives the class of the f (x) calculation result of the user terminal from the ranking unit 23a, the pilot pattern allocating unit 23b refers to the class in the same pilot pattern management table TBL as the class, and the peak-to-average power in the class A sequence number of an unused pilot pattern is obtained in order of good characteristics, and the sequence number of the pilot pattern is input to the downlink signal baseband processing unit 24.

The downlink signal baseband processing unit 24 encodes the user data, the pilot pattern sequence number, and the TFC, and then modulates and multiplex-converts and inputs the encoded data to the transmitter of the radio device 21. The transmitter frequency-converts the baseband signal to a radio frequency, amplifies it, and transmits it to the user terminal.
According to the fifth embodiment, since a pilot pattern is determined using a plurality of parameters, a pilot having good peak-to-average power characteristics can be reliably assigned to a user terminal with high transmission power, and distortion in the transmission amplifier can be prevented. It can be prevented from occurring.

The following two methods are also conceivable as pilot pattern allocation methods.
The first method considers the peak-to-average power characteristics of the data portion. The worse the peak-to-average power characteristic of the data part, the smaller the influence of the peak-to-average power characteristic of the pilot part on the entire transmission signal. Therefore, a pilot pattern having a good peak-to-average power characteristic is preferentially assigned to a user having a good peak-to-average power characteristic in the data portion.
The second method is a method that considers how to use the pilot signal. When pilot signals are used separately for SIR estimation and channel estimation, the reception quality of the channel estimation pilot is generally more important than SIR estimation. For this reason, a pilot pattern with good peak-to-average power characteristics is assigned to the channel estimation pilot.

(F) Sixth Embodiment In the sixth embodiment, a pilot pattern is assigned to a user terminal for each use of a pilot in a base station, and a predetermined pilot pattern is switched and used in the user terminal according to the use of the pilot.
FIG. 15 is a block diagram of the base station of the sixth embodiment, where the same reference numerals are given to the same parts as in FIG. As a method of dividing the usage of the pilot, a case where the pilot usage is divided into two for the data transmission interval and for the non-data transmission interval will be described, but there is another division. For example, as a method of dividing the use of pilots, a method of dividing into three for channel estimation, CQI measurement, and uplink synchronization can be considered.
The pilot pattern management table TBL stored in the storage unit 15 includes a plurality of pilot pattern management tables (rank tables) for each pilot application. That is, the pilot pattern management table TBL includes a rank table TBL1 for data transmission sections and a rank table TBL2 for non-data transmission sections. The ranking tables TBL1 and TBL2 are created as follows, for example. That is, the pilot patterns are ranked in order of goodness based on the peak-to-average power characteristics, the pilot patterns are classified into a class having a good peak-to-average power characteristic and a class having a good peak-to-average power characteristic. And the ranking table TBL2 is created with the bad class as the class for the non-data transmission section.
When the pilot pattern allocation unit 14 receives the pilot pattern allocation request from the uplink control unit 13, the pilot pattern allocation unit 14 determines the pilot pattern corresponding to each application in turn with reference to the order tables TBL1 and TBL2, or the transmission power of the user terminal Then, the pilot pattern for each application is adaptively determined in consideration of position information and the like, and the sequence number is returned to the uplink control unit 13. The uplink control unit 13 inputs the received sequence number of each pilot pattern for each application to the downlink signal baseband processing unit 16.
The downlink signal baseband processing unit 16 encodes the user data and the sequence number of each application-use pilot pattern, then modulates and multiplexes and inputs the data to the transmitter of the wireless device 11 and transmits it to the user terminal 2 from the transmitter. The user terminal 2 demodulates and stores the sequence number of the pilot pattern for each application from the received signal, and generates a pilot pattern corresponding to the application.
The case has been described above where the ranking table TBL1 is created for the pilot pattern of the good class for the data transmission interval, and the ranking table TBL2 is created for the bad class for the non-data transmission interval. However, if the pilot for data transmission section and the pilot for non-data transmission section are transmitted orthogonally in the frequency domain or time domain, create the respective rank tables including the same pilot pattern in the rank tables TBL1 and TBL2. You may do it.
In addition, as a method for determining a pilot pattern for each application, the methods described in the first to fifth embodiments and each modification can be used.
In addition, when data transmission section pilots are managed so as to be orthogonal in the frequency domain or the time domain for all user terminals in the same cell, the same data transmission section pilot pattern may be assigned to a plurality of user terminals. . In this case, another pilot pattern is assigned to each user terminal using the methods of the first to fifth embodiments for the non-data transmission section pilot.

FIG. 16 is a block diagram of a user terminal according to the sixth embodiment. Components identical with those of the user terminal according to the second embodiment shown in FIG.
The receiver of the radio device 31 converts the received signal from a radio frequency to a baseband frequency and inputs it to the downlink signal baseband processing unit 32.
The baseband processing unit 32 separates user data, pilot sequence numbers for each application, TFC information, and the like from the input signal. The pilot pattern management unit 51 receives the pilot sequence number for each application, and distinguishes and stores the pilot sequence numbers for the data transmission section and the non-data transmission section.
The transmission signal control unit 36 inputs the modulation scheme and coding rate included in the TFC information to the modulation units 37a and 37b and the coding units 38a and 38b, respectively. Also, the transmission control unit 36 determines the use of the pilot pattern based on the state of the user terminal (data transmission interval, non-data transmission interval), and requests the pilot pattern sequence number corresponding to the use from the pilot pattern management unit 51. The pilot pattern sequence number received from the pilot pattern management unit 51 is input to the pilot pattern generation unit 33. The pilot pattern generation unit 33 generates a pilot signal based on the input pilot sequence number.
The encoding units 38a and 38b encode user data and control information with the input encoding method and encoding rate, and the modulation units 37a and 37b modulate the input data with the input modulation method, and the power control / multiplexing unit 39 performs predetermined power control on user data, control information, and pilot signals, and then multiplexes them and inputs them to the transmitter of the radio 31. The transmitter frequency-converts the baseband signal to a radio frequency, amplifies it, and transmits it to the base station.
When the pilot pattern management unit 51 receives new assignment information of a pilot pattern, the pilot pattern management unit 51 updates the held pilot pattern. The update cycle may be different for the data transmission section and the non-data transmission section.
According to the sixth embodiment, a pilot pattern can be assigned to a user terminal for use.

(G) Seventh Example In a mobile communication system, in order to suppress inter-cell interference, communication is performed using a different frequency for each cell. Similarly, interference between cells can be reduced by assigning several different pilot patterns to cells or sectors.
By the way, in order to transmit data efficiently, it is necessary to multiplex and transmit a pilot pattern having a CM smaller than that of the data. In the case of GCL or CAZAC pilot sequences, the CM varies depending on the sequence number, and the shorter the sequence length, the smaller the number of pilot patterns having a smaller CM (see FIG. 30). For example, when data modulation is performed with π / 2-BPSK, the number of pilot patterns having a CM smaller than that of π / 2-BPSK is small. For this reason, repeated use in each cell using only a CM pilot pattern smaller than that of π / 2-BPSK may cause the same pilot pattern to be used between adjacent cells, resulting in sufficient inter-cell interference reduction. The effect is not obtained.
On the other hand, as the modulation scheme becomes higher (QPSK, 16QAM, etc.), the number of pilot patterns that can be transmitted simultaneously with data increases. Therefore, a pilot pattern corresponding to the modulation scheme may be used in each cell. Further, if the number of pilot patterns used for each modulation method is adaptively changed, a larger interference reduction effect can be obtained.
FIG. 17 is a table showing the number of divisions and the number of pilot patterns that can be used for each modulation scheme when 5 MHz is used after frequency division by a plurality of user terminals. Since the total bandwidth is constant, the greater the number of frequency divisions, the smaller the frequency bandwidth per user and the shorter the pilot pattern length (sequence length) used. As the pilot pattern length becomes shorter, the number of patterns that can be used during data transmission for each modulation method decreases. For example, when the sequence length is 17, the number of pilot patterns of GCL / CAZAC having a CM smaller than the CM of π / 2-BPSK is reduced to 2, and the same pilot pattern must be assigned to the cell every two cells. On the other hand, since there are eight pilot patterns having CMs smaller than those of QPSK, in the case of QPSK, the same pilot pattern can be assigned to the cells every eight cells.
The seventh embodiment pays attention to the fact that the number of pilot patterns that can be used varies depending on the modulation method, and is characterized by changing both the number of pilot patterns to be repeatedly used and the pilot pattern for each modulation method. is there. According to the seventh embodiment, the pilot pattern used for each modulation scheme in the same cell can be made different, and different pilot patterns can be assigned in adjacent cells or adjacent sectors. When the sequence length adaptively changes as shown in FIG. 17, N _B '(≦ N _B ), N _Q ′ (≦ N _Q −N _B ′) pieces corresponding to the modulation scheme for each sequence length. What is necessary is just to use a pilot pattern repeatedly.
In the prior art, the number of pilot patterns and the number of pilot patterns are not changed depending on the modulation scheme, and the number of pilot patterns that can be used for all modulation schemes is insufficient in GCL / CAZAC.
For this reason, in the prior art, the same pilot pattern must be used even if the modulation method is different within the same cell or sector, and different pilot patterns cannot be assigned in adjacent cells or adjacent sectors, resulting in interference. Reduction effect is reduced.
Base Station FIG. 18 is a block diagram of the base station of the seventh embodiment, and the same parts as those in FIG.
The pilot pattern management table setting unit 61 sets pilot patterns so that pilot patterns used in adjacent base stations or adjacent sectors are different, and pilot patterns of the same base station or the same sector are different for each modulation scheme, Store in the storage unit 15. For example, as shown in FIG. 19, when each pilot pattern (sequence number k) of a CAZAC sequence having a predetermined length is ranked based on peak-to-average power characteristics, the number of pilot patterns that can be used for the π / 2-BPSK modulation scheme 3 and the pilot pattern sequence numbers are k ₁ to k ₃ , the number of pilot patterns that can be used in the QPSK modulation scheme is 7, and the pilot pattern sequence numbers are k ₄ to k ₁₀ . In such a case, in the hexagonal cell arrangement shown in FIG. 20, a pilot pattern indicated by (m, n) is assigned to each of the cells BS1 to BS7. m means that the m-th order pilot pattern is assigned as the π / 2-BPSK pilot pattern, and n means that the n-th order pilot pattern is assigned as the QPSK pilot pattern.
When pilot patterns are assigned to each cell as shown in FIG. 20, pilot patterns used in adjacent base stations are different, and pilot patterns in the same base station are different for each modulation scheme. 19 and 20 show cases where two modulation schemes, BPSK and QPSK, are assumed, but 8 QPSK, 16 QPSK, and the like can also be considered.
The pilot pattern management table setting unit 61 inputs the pilot pattern sequence number of each modulation method based on the pilot pattern (m, n) assigned to the base station, and the storage unit 15 sets the input pilot pattern sequence number as the modulation method. A corresponding pilot pattern management table TBL is created and stored. The above is a case where the pilot pattern sequence number of each modulation scheme is set and stored for one sequence length, but as shown in FIG. 21, the pilot pattern sequence number of each modulation scheme is set and stored for a plurality of sequence lengths. can do. In this way, when the sequence length adaptively changes, it is possible to cause the user terminal to use a pilot pattern corresponding to the modulation scheme for each sequence length.
If the pilot pattern allocation unit 14 receives a pilot pattern allocation request including data indicating the modulation scheme and sequence length of the user terminal from the uplink control unit 13, the pilot pattern allocation unit 14 refers to the table TBL (FIG. 21) according to the sequence length and modulation scheme. The obtained pilot pattern sequence number is acquired and responded to the uplink control unit 13. The uplink control unit 13 inputs the sequence length and sequence number of the received pilot pattern to the downlink signal baseband processing unit 16. The downlink signal baseband processing unit 16 encodes the user data, the sequence length and sequence number of the pilot pattern, and transmits the encoded data to the user terminal 2 from the wireless device 11. The user terminal 2 demodulates the pilot pattern sequence length and sequence number from the received signal, generates a pilot pattern of the sequence length and sequence number, adds it to the user data, and transmits it to the base station.
In FIG. 20, one pilot pattern is assigned to each of the cells BS1 to BS7 for each modulation scheme. However, one or more pilot patterns may be assigned for each modulation scheme as shown in FIG. In FIG. 22, two QPSK pilot patterns are assigned to each cell.

User Terminal FIG. 23 is a block diagram of the user terminal of the seventh embodiment, and the same reference numerals are given to the same parts as those of the user terminal in the second embodiment of FIG.
The receiver of the radio device 31 converts the received signal from a radio frequency to a baseband frequency and inputs it to the downlink signal baseband processing unit 32.
The baseband processing unit 32 separates user data, pilot sequence length / sequence number, TFC information, and the like from the input signal. The pilot pattern generation unit 33 generates a pilot signal based on the received pilot pattern sequence length / sequence number. The control information creation unit 35 creates and outputs control information, and the transmission signal control unit 36 inputs the modulation scheme and coding rate included in the TFC information to the modulation units 37a and 37b and the coding units 38a and 38b, respectively. . The encoding units 38a and 38b encode user data and control information with the input encoding method and encoding rate, and the modulation units 37a and 37b modulate the input data with the input modulation method, and the power control / multiplexing unit 39 performs predetermined power control on user data, control information, and pilot signals, and then multiplexes them and inputs them to the transmitter of the radio 31. The transmitter frequency-converts the baseband signal to a radio frequency, amplifies it, and transmits it to the base station.
Specific Pilot Pattern Setting Example FIG. 24 is a specific pilot pattern setting example when the number of pilot patterns (number of repetitions) that can be used in each modulation scheme is three, and three cells A, B, and C adjacent to each other. It is an example of a pilot pattern set to. (A) is a pilot pattern management table set in cell A, (B) is set in cell B, and (C) is a pilot pattern management table set in cell C. The pilot patterns used in adjacent cells are different, and the pilot patterns in the same cell are set to be different for each modulation scheme.
FIG. 25 is an example of a pilot pattern assigned to each cell (base station) when the hexagonal cell arrangement of FIG. 20 is further expanded.
-1st modification In the above Example, it is an example in case a base station determines a suitable pilot pattern each time and notifies it to a user terminal, but a part for multiple uses (for several modulation systems) is put together from a base station. It is also possible to notify the terminal of the application-specific sequence number at the same time. When there is only a pilot pattern management table for one sequence length in the storage unit 15, it is sufficient to notify all user terminals in the cell using the broadcast channel. When there are a plurality of sequence lengths, a table corresponding to the sequence length used by the user terminal can be individually notified on an individual channel, in addition to being collectively transmitted on the broadcast channel.
When pilot pattern sequence numbers for a plurality of modulation schemes are transmitted to the user terminal for each of one or more sequence lengths from the base station, the configuration of the user terminal is the same as in FIG. 16, and the operation is as follows.
The receiver of the radio device 31 converts the received signal from a radio frequency to a baseband frequency and inputs it to the downlink signal baseband processing unit 32. The baseband processing unit 32 separates user data, pilot sequence number for each sequence length / modulation method, TFC information, and the like from the input signal. The pilot pattern management unit 51 receives and stores a pilot sequence number for each sequence length / modulation method. The transmission signal control unit 36 inputs the modulation scheme and coding rate included in the TFC information to the modulation units 37a and 37b and the coding units 38a and 38b, respectively. The transmission control unit 36 adaptively determines the sequence length and modulation scheme used by the user terminal, requests the pilot pattern management unit 51 for a pilot pattern sequence number corresponding to the sequence length and modulation scheme, and transmits the pilot pattern. The pilot pattern sequence number received from the management unit 51 is input to the pilot pattern generation unit 33. The pilot pattern generation unit 33 generates a pilot signal based on the input pilot sequence number. The encoding units 38a and 38b encode user data and control information with the input encoding method and encoding rate, and the modulation units 37a and 37b modulate the input data with the input modulation method, and the power control / multiplexing unit 39 performs predetermined power control on user data, control information, and pilot signals, and then multiplexes them and inputs them to the transmitter of the radio 31. The transmitter frequency-converts the baseband signal to a radio frequency, amplifies it, and transmits it to the base station.

Second Modification In the seventh embodiment, the pilot pattern is assigned to the user terminal based on the modulation scheme without distinguishing between the data transmission period and the non-data transmission period, but the pilot pattern for the non-data transmission period is also a sequence length. It can be set for each and notified to the user terminal. In this case, the pilot pattern for the non-data transmission section is set to be different in the adjacent cell or the adjacent sector.
FIG. 26 shows an example of a pilot pattern management table TBL considering a pilot pattern in a non-data transmission section.
If the pilot pattern allocation unit 14 (FIG. 18) receives a pilot pattern allocation request including data indicating the modulation scheme and sequence length of the user terminal from the uplink control unit 13, the pilot pattern allocation unit 14 (FIG. 18) refers to the table TBL (FIG. 26). The first pilot pattern sequence number corresponding to the sequence length and modulation scheme, and (2) the second pilot pattern for the non-transmission data interval corresponding to the sequence length are acquired and responded to the uplink control unit 13 To do. The uplink control unit 13 inputs the sequence lengths and sequence numbers of the received first and second pilot patterns to the downlink signal baseband processing unit 16. The downlink signal baseband processing unit 16 encodes the user data, the sequence lengths and sequence numbers of the first and second pilot patterns, and transmits them to the user terminal 2 from the radio 11. The user terminal 2 demodulates and stores the sequence length and sequence number of the first and second pilot patterns from the received signal, and generates a predetermined pilot pattern according to the use (data transmission period / non-data transmission period). Send to base station.
The following three methods can be considered as how to determine the non-data transmission section pilot.
(1) In addition to classification according to the modulation scheme of the data transmission section, a pilot class for non-data transmission section is added and has a unique number of repetitions.
(2) Use the same pilot pattern as any modulation method.
(3) Use the pilot pattern used in the previous data transmission interval.
FIG. 24 shows a pilot pattern management table in the case of (1).
As described above, according to the seventh embodiment, the pilot pattern used for each modulation scheme in the same cell can be made different, and different pilot patterns can be assigned in adjacent cells or adjacent sectors. Inter-sector or inter-sector interference can be reduced.
Further, since the pilot pattern for the non-data transmission section is made different from the pilot pattern for the data transmission section, and the pilot pattern for the non-data transmission section is set to be different in the adjacent cell or the adjacent sector, it is more effective. Inter-cell or inter-sector interference can be reduced.

・ Additional notes
(Appendix 1)
In a base station in a wireless communication system using a pilot signal having a predetermined pattern at the time of transmission from a user terminal to a base station,
A storage unit for storing a rank table for peak-to-average power characteristics of each pilot pattern;
A pilot pattern allocation unit that allocates pilot patterns to terminals in order of good peak-to-average power characteristics with reference to the rank table,
A pilot pattern notifying unit for notifying the terminal of the pilot pattern;
A base station characterized by comprising:
(Appendix 2)
In a base station in a wireless communication system using a pilot signal having a predetermined pattern at the time of transmission from a user terminal to a base station,
A storage unit for storing a rank table for peak-to-average power characteristics of each pilot pattern;
A transmission status identification unit for identifying the transmission status of the user terminal,
A pilot pattern allocating unit that adaptively allocates pilot patterns in order according to the transmission status of the user terminal to the user terminals;
A pilot pattern notifying unit for notifying the terminal of the pilot pattern;
A base station characterized by comprising:
(Appendix 3)
The transmission situation identification unit extracts the difference from the transmission power or maximum transmission power of the user terminal from the received signal from the user terminal,
The pilot pattern allocating unit allocates a pilot pattern with good peak-to-average power characteristics to a terminal having a large transmission power or a user terminal having a small difference from the maximum transmission power with reference to the rank table.
The base station according to Appendix 2, wherein
(Appendix 4)
The transmission situation identification unit extracts the location information of the user terminal from the received signal from the user terminal, calculates the distance between the user terminal and the base station using the location information,
The pilot pattern allocating unit allocates a pilot pattern having a good peak-to-average power characteristic to a user terminal having a large distance with reference to the ranking table.
The base station according to Appendix 2, wherein
(Appendix 5)
The storage unit classifies and stores the pilot pattern ranking table;
The transmission situation identification unit identifies the communication capability of the user terminal,
The pilot pattern allocation unit allocates a pilot pattern of a class corresponding to the communication capability of the user terminal to the user terminal.
The base station according to Appendix 2, wherein
(Appendix 6)
The storage unit classifies and stores the pilot pattern ranking table;
The transmission situation identification unit identifies the channel quality indication CQI of the user terminal,
The pilot pattern allocation unit allocates a pilot pattern of a class corresponding to the CQI to a user terminal.
The base station according to Appendix 2, wherein
(Appendix 7)
The storage unit classifies and stores the pilot pattern ranking table;
The transmission situation identification unit obtains a function value of a function having the channel quality display CQI of the user terminal, the distance between the user terminal and the base station, and the modulation method of the user terminal as a variable,
The pilot pattern allocation unit allocates a pilot pattern of a class corresponding to the function value to a user terminal.
The base station according to Appendix 2, wherein
(Appendix 8)
The storage unit classifies and stores the pilot pattern ranking table;
The transmission situation identification unit identifies real-time properties of user data transmitted by the user terminal,
The pilot pattern allocation unit allocates a pilot pattern of a class according to the presence or absence of real time property of the user data to a user terminal,
The base station according to Appendix 2, wherein
(Appendix 9)
The storage unit classifies and stores the pilot pattern ranking table;
The transmission situation identification unit identifies the modulation scheme of the user terminal,
The pilot pattern allocation unit allocates a pilot pattern of a class according to a modulation scheme of the user data to a user terminal;
The base station according to Appendix 2, wherein
(Appendix 10)
In a wireless communication system using a pilot signal having a predetermined pattern at the time of transmission from a user terminal to a base station,
The base station
A storage unit for storing a rank table for peak-to-average power characteristics of each pilot pattern according to use,
A pilot pattern allocating unit that allocates pilot patterns according to applications to user terminals with reference to the ranking table,
A pilot pattern notifying unit for notifying a user terminal of a pilot pattern corresponding to the application;
The user terminal is equipped with
A storage unit for storing pilot patterns according to applications,
A pilot generator that generates a pilot pattern according to the application;
A transmitter for transmitting the pilot pattern;
A wireless communication system comprising:
(Appendix 11)
The wireless communication system according to appendix 10, wherein the pilot pattern is used separately for a data transmission section and a non-data transmission section.
(Appendix 12)
The pilot pattern allocation unit adaptively allocates a pilot pattern for a data transmission interval to a user terminal from the rank table for the data transmission interval.
The wireless communication system according to supplementary note 10, characterized by the above.
(Appendix 13)
The pilot pattern allocation unit adaptively allocates pilot patterns for non-data transmission sections to user terminals from a rank table for non-data transmission sections.
The wireless communication system according to supplementary note 10, wherein
(Appendix 14)
The pilot pattern is a CAZAC sequence or a GCL sequence,
The base station according to appendices 1 to 9.
(Appendix 15)
In a pilot pattern determination method of a pilot signal in a wireless communication system using a pilot signal at the time of transmission from a user terminal to a base station,
Creating and storing a rank table for the peak-to-average power characteristics of each pilot pattern;
Assigning pilot patterns to terminals in descending order of peak-to-average power characteristics with reference to the ranking table;
Notifying the terminal of the pilot pattern;
A pilot pattern determination method comprising:
(Appendix 16)
In a pilot pattern determination method of a pilot signal in a wireless communication system using a pilot signal at the time of transmission from a user terminal to a base station,
Creating a rank table for the peak-to-average power characteristics of each pilot pattern;
Identifying the data transmission status of the user terminal;
A step of adaptively assigning to the user terminal a pilot pattern having a rank according to the data transmission situation of the user terminal;
A pilot pattern determination method comprising:
(Appendix 17)
In the data transmission situation identification step, extract the difference from the transmission power or the maximum transmission power of the user terminal from the received signal from the user terminal,
In the pilot pattern assignment step, a pilot pattern having a good peak-to-average power characteristic is assigned to a user terminal having a large transmission power or a user terminal having a small difference from the maximum transmission power with reference to the rank table.
The pilot pattern determining method according to supplementary note 16, wherein the pilot pattern is determined.
(Appendix 18)
In the data transmission situation identification step, the position information of the user terminal is extracted from the received signal from the user terminal, the distance between the user terminal and the base station is calculated using the position information,
In the pilot pattern assignment step, a pilot pattern having a good peak-to-average power characteristic is assigned to a user terminal having a large distance with reference to the rank table.
The pilot pattern determining method according to supplementary note 16, wherein the pilot pattern is determined.
(Appendix 19)
In the ranking table creating step, classifying the pilot pattern ranking table into classes,
In the data transmission situation identification step, whether the situation of the user terminal is transmitting data or not transmitting data,
In the pilot pattern assigning step, if data transmission is in progress, a class pilot pattern corresponding to the data transmission interval is assigned to the user terminal, and if data non-transmission is in progress, a class pilot pattern corresponding to the data non-transmission interval is assigned to the user terminal. Assign to devices,
The pilot pattern determining method according to supplementary note 17, characterized by:
(Appendix 20)
In the ranking table creating step, classifying the pilot pattern ranking table into classes,
In the data transmission situation identification step, the communication capability of the user terminal is identified,
In the pilot pattern assignment step, a class of pilot pattern corresponding to the communication capability of the user terminal is assigned to the user terminal.
The pilot pattern determining method according to supplementary note 16, wherein the pilot pattern is determined.
(Appendix 21)
In the ranking table creating step, classifying the pilot pattern ranking table into classes,
In the data transmission situation identification step, identify the channel quality indication CQI of the user terminal,
In the pilot pattern allocation step, a pilot pattern of a class corresponding to the CQI is allocated to the user terminal.
The pilot pattern determining method according to supplementary note 16, wherein the pilot pattern is determined.
(Appendix 22)
In the ranking table creating step, classifying the pilot pattern ranking table into classes,
In the data transmission situation identification step, the channel quality display CQI of the user terminal, the distance between the user terminal and the base station, the function value of the function having the modulation scheme of the user terminal as a variable,
In the pilot pattern allocation step, a pilot pattern of a class corresponding to the function value is allocated to the user terminal.
The pilot pattern determining method according to supplementary note 16, wherein the pilot pattern is determined.
(Appendix 23)
In the ranking table creating step, classifying the pilot pattern ranking table into classes,
In the data transmission situation identification step, the real-time property of user data transmitted by the user terminal is identified,
In the pilot pattern assignment step, a pilot pattern of a class corresponding to the presence / absence of real time property of the user data is assigned to a user terminal.
The pilot pattern determining method according to supplementary note 16, wherein the pilot pattern is determined.
(Appendix 24)
In the ranking table creating step, classifying the pilot pattern ranking table into classes,
In the data transmission situation identification step, the modulation scheme of the user terminal is identified,
In the pilot pattern assignment step, a pilot pattern of a class corresponding to a modulation scheme of the user data is assigned to a user terminal.
The pilot pattern determining method according to supplementary note 16, wherein the pilot pattern is determined.
(Appendix 25)
In a base station in a wireless communication system using a pilot signal having a predetermined pattern at the time of transmission from a user terminal to a base station,
A storage unit that stores pilot patterns set so that pilot patterns used in adjacent base stations or adjacent sectors are different, and pilot patterns in the same base station or the same sector are different for each application,
With reference to the correspondence relationship between the application and the pilot, a pilot pattern assignment unit that assigns a pilot pattern corresponding to the use of the user terminal to the user terminal,
A pilot pattern notifying unit for notifying a user terminal of a pilot pattern according to the application;
A base station in a wireless communication system, comprising:
(Appendix 26)
The application is a modulation scheme, and the pilot pattern is set so that the pilot pattern in the same base station or the same sector differs for each modulation scheme.
29. A base station in a wireless communication system according to appendix 25.
(Appendix 27)
A pilot pattern is set for each data transmission interval and non-data transmission interval and for each modulation scheme, and the pilot pattern allocating unit distinguishes between the data transmission interval and the non-data transmission interval, and assigns the pilot pattern to the user terminal. assign,
27. A base station in a wireless communication system according to supplementary note 26.
(Appendix 28)
The number of pilot patterns used for the allocation is set in the base station by changing for each modulation scheme.
27. A base station in a wireless communication system according to supplementary note 26.

DESCRIPTION OF SYMBOLS 1 Base station 2 Mobile terminal 11 Radio | wireless machine 12 Uplink signal baseband process part 13 Uplink control part 14 Pilot pattern allocation part 15 Storage part 16 Downlink signal baseband process part TBL Pilot pattern management table

Claims (4)

In a base station in a wireless communication system using a pilot signal having a pilot pattern of a predetermined CAZAC sequence at the time of transmission from a user terminal to the base station,
Different pilot patterns of the CAZAC sequences used in the base station or neighboring sectors adjacent, and the pilot patterns of the CAZAC sequence in the same base station or the same sector is set to be different for each application, use and the pilot pattern Based on the correspondence relationship, a pilot pattern allocation unit that allocates a pilot pattern of a CAZAC sequence according to the use of the user terminal to the user terminal,
Pilot pattern notification unit for notifying the user terminal of the pilot pattern of the CAZAC sequence according to the application,
A base station in a wireless communication system, comprising: The application is a modulation scheme, and the pilot pattern is set so that a pilot pattern of a CAZAC sequence in the same base station or the same sector differs for each modulation scheme.
The base station in the radio | wireless communications system of Claim 1 characterized by the above-mentioned. A CAZAC sequence pilot pattern is set for each data transmission interval and non-data transmission interval and for each modulation scheme, and the pilot pattern allocating unit distinguishes between a data transmission interval and a non-data transmission interval . Assign pilot patterns to user terminals,
The base station in the radio | wireless communications system of Claim 2 characterized by the above-mentioned. The number of pilot patterns of the CAZAC sequence used for the allocation is set in the base station by varying for each modulation method,
The base station in the radio | wireless communications system of Claim 2 characterized by the above-mentioned.