Wireless communication apparatus and reference signal generating method

REPUBLIC OF POLAND (12) TRANSLATION OF THE EUROPEAN PATENT (19) pl (ii) PL / EP 3337217

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Patent Office of the Republic of Poland (96) Date and number of the European patent application:

29.10.2010 18155351.2 (97) The grant of the European patent was announced:

10/07/2019 European Patent Bulletin 2019/28 EP 3337217 B1 (13) T3 (51) Int.CI.

H04W16 / 28 (2009.01)

H04J 11/00 (2006.01)

H04B 7/024 (2017.01)

H04L 5/00 (2006.01)

H04J 13/00 (2011.01)

H04L 1/20 (2006.01)

H04L 1/00 ​​(2006.01) (54) Title of the invention:

A device for wireless communication and a way of generating a reference signal (3 °) rv

Priority:

10.10.2009 JP 2009 250 450 (43) The application was announced:

20.06.2018 in the European Patent Bulletin No. 2018/25 (45) The filing of the patent translation was announced:

31.01.2020 Patent Office News 2020/01 (73) Patent holder:

Sun Patent Trust, New York, US (72) Creator (s) of the invention:

(74)

TAKASHIIW Al, Osaka, JP DAICHIIMAMURA, Osaka, JP AKIHIKO NISHIO, Osaka, JP YOSHIHIKO OGAWA, Osaka, JP MASARU FUKUOKA, Osaka, JP

Proxy:

thing, pat. Sebastian Walkiewicz DENNEMEYER &amp; ASSOCIATES SP. Z OO ul. Swarzewska 57/1

01-821 Warsaw

Attention:

Within nine months of publication of the information on the grant of the European patent, any person may lodge an objection to the European Patent Office regarding the granted European patent. The objection shall be made in the form of a reasoned statement. It is considered to be filed only when the opposition fee has been paid (Article 99 (1) of the Convention on the Grant of European Patents).

PL-PAT-2012-2218

EP 3 337 217 B1

A device for wireless communication and a method of generating a reference signal

Description Technical field [0001] The present invention relates to a radio communication device and a method for generating a reference signal that generates a reference signal used for estimating channel quality.

Technical background [0002] In the LTE-Advanced uplink, which is an improved 3GPP LTE (3rd Generation Partnership Project Long Term Evolution), work is underway to introduce UL CoMP (coordinated multi-point transmission and reception). CoMP is a technique mainly aimed at increasing the bandwidth of a terminal located on the edge of a cell by implementing transmitting and receiving between multiple cells (base stations) in a coordinated manner using a terminal.

[0003] In the case of UL CoMP, the reception quality is improved by receiving and combining a signal transmitted from one terminal in many cells (base stations). At this time, in a group (hereinafter referred to as CoMPs) of cells that perform transmitting and receiving in a coordinated manner, terminal planning is also implemented in a coordinated manner between the multiple cells that make up the CoMPs to reduce the impact of intercellular interference.

[0004] On the other hand, LTE uses the URS (sounding reference signal) of the uplink. The term "probe" refers here to the estimation of channel quality and SRS is transmitted by multiplexing in time a special symbol with data mainly to estimate the CQI (channel quality indicator) of the uplink data channel. [0005] As SRS, LTE uses the ZC (Zadoff-Chu) sequence. Characterization of the ZC sequence includes the fact that CS-ZC (ZC cyclically shifted) sequences generated by cyclic shifting of the ZC sequence with any ZC sequence number with a time length greater than the maximum propagation delay time are ideally orthogonal (inter-code interference is zero). However, ZC sequences having other ZC sequence numbers are not orthogonal and cross-correlation (inter-code interference) occurs at a certain level of "1 / length of the ZC sequence". In accordance with the above characteristics, LTE provides a ZC sequence group that specifies the ZC sequence numbers for each of the transmit bands available in the cells and one ZC sequence group is assigned to each cell (see, e.g., Non-Patent Document 1). Of these ZC sequence groups, 30 are defined and to reduce intercellular interference, different ZC sequence groups are assigned to adjacent cells.

[0006] In order to improve reception quality in the above CoMP UL, it is necessary to accurately estimate channel quality using SRS. Therefore, first you must select the ZC sequence number for the SRS transmitted by the terminal where UL CoMP is used, i.e. the terminal (henceforth referred to as the "CoMP terminal") where the transmission signals are received and combined in many cells. Two ways can be considered as a way of making this choice (selection method 1 and selection method 2).

[0007] Selection method 1 is a method for selecting, for the SRS of a CoMP terminal, a ZC sequence assigned to a cell (hereinafter referred to as "serving cell") that transmits control information, such as planning information, to the terminal. That is, in the cell serving the CoMP terminal, the terminal (hereinafter referred to as "non-CoMP terminal") to which UL CoMP is not used, uses the same ZC sequence for the SRS as the CoMP terminal.

[0008] Selection method 2 is a method for selecting, for the SRS of a CoMP terminal, a ZC sequence having a ZC sequence number other than a ZC sequence number for use by a non-CoMP terminal within a CoMP assembly. That is, in the SRS of the CoMP terminal, the ZC sequence belonging to the ZC sequence group (ZC sequence group not used within the CoMP assembly, i.e. the ZC sequence group used outside the CoMP assembly) is used other than the ZC sequence groups assigned to the cells in the CoMP assembly.

[0009] NPL 2 discusses limitations in terms of UL CoMP by providing a performance comparison between different reference signal patterns.

[0010] NPL 3 describes the approach to receive UL CoMP by considering cell signal processing to suppress inter-cell interference with a common channel among users in neighboring cells using relative UE information in neighboring cells. [0011] NPL 4 refers to physical channels for evolved UTRA.

[0012] PL1 describes a method of allocating sequences that, while maintaining the number of Zadoff-Chu sequences needed to form a sequence group, is configured to reduce correlation between different sequence groups and between the sequence groups themselves.

[0013] PL2 describes a radio transmitting device and method of radio transmitting that can reduce the amount of processing or the amount of memory while maintaining the effect of randomization of interference with another cell.

[0014] PL3 describes a wireless end device in which the frequency of inter-sequence interferences between the pre-hop reference reference signal and the post-hop reference signal can be reduced to improve the randomization effect obtained by skipping the sequence.

List of references

Non-patent literature [0015]

NPL13GPP TS36.211 V8.7.0.5.5.1 Generation of the reference signal sequence, Physical Channels and Modulation (Release 8)

NPL2R1-093307 Uplink DM RS performance evaluation from CoMP viewpoint Nokia Siemens Networks, Nokia

NPL3R1-093366 Uplink coordinated multi-point reception with distributed inter-cell interference suppression for LTE-A Alcatel-Lucent Shanghai Bell, Alcatel-Lucent

NPL43GPP TS 36.211 V8.8.0 Evolved Universal Terrestrial Radio (E-UTRA) Physical Channels and Modulation (Release 8)

Patent Literature [0016]

PL1WO2008 / 155907 A1

PL2WO2008 / 111317 A1

PL3WO2009 / 084224 A1

Summary of the Invention

Technical problem [0017] However, with the above selection method 1 there is a problem that strong interference occurs within the CoMP. This issue will be described in detail below.

[0018] As shown in FIG. 1, when the CoMP terminal transmits one transmit signal to multiple cells at different distances, each cell receives a signal with a different receive synchronization, which complicates the issue of controlling transmission synchronization. Therefore, in one cell, erroneous synchronization control of transmission causes that synchronization of SRS reception transmitted by the CoMP terminal exceeds the pre-set time range, which causes CS-ZC sequences using the same ZC sequence numbers to cease to be orthogonal.

[0019] When the synchronization of the SRS reception transmitted by the CoMP terminal is delayed by exceeding a predetermined time length, the large SRS correlation value of the CoMP receiving terminal goes beyond the predetermined CS detection window (cyclic shift) and overlaps the CS detection window of the terminal non-CoMP, as shown by the SRS output correlation (delay profile) in FIG. 2.

[0020] As a result, it is not possible to detect CoMP terminal SRS reception in the CS detection window of the CoMP terminal. The receiving SRS correlation value of the CoMP terminal overlapping the CS detection window of a non-CoMP terminal becomes a significant interference component, so that in the CS detection window of a non-CoMP terminal it is difficult to distinguish the interference component from the signal component, which reduces the accuracy of CQI estimation.

[0021] Also, when the synchronization of the SRS reception transmitted by the CoMP terminal is delayed, the SRS of the non-CoMP terminal is always strongly interfered by CS-ZC sequences that are no longer orthogonal in the CoMP terminal until the transmission synchronization control is updated. Thus, in this cell, the accuracy of CQI estimation is deteriorated, which means that the proper planning is not carried out correctly, and thus the system capacity is deteriorated.

[0022] With the above selection method 2, there is a problem in that interference increases outside the CoMP. This issue will be described in detail below.

[0023] When the CoMP terminal uses ZC sequence numbers to be used outside of the CoMP assembly, the intercellular interference between the non-CoMP terminal (conventional LTE terminal), outside the CoMP assembly and the CoMP terminal increases, thereby reducing the accuracy of the CQI estimation. Because the number of ZC sequence numbers (ZC sequence group) that the terminal can use is limited when the ZC sequence numbers outside the comp are used, the distance to the non-CoMP terminal in a cell using the same ZC sequence number is shortened, therefore intercellular interference (cross-correlation) increases. This condition is shown in FIG. 3.

[0024] FIG. 3 shows ZC sequence numbers used in cells when sequence numbers from 1 to 19 are available in the system, for ease of explanation. In FIG. 3 one cell is represented in the shape of a hexagon, and the ZC sequence numbers are allocated such that cells using the same ZC sequence number are spaced apart as far as possible to limit intercellular interference. As shown in FIG. 3, it is assumed that the cells assigned ZC sequence numbers 1, 2 and 3 form one CoMP assembly, and the CoMP terminal in the CoMP assembly uses the ZC sequence number 16, not used in the CoMP assembly as the ZC sequence for SRS. In this case, because the distance to the cell using the ZC sequence number 16 is shortened and the interference suppression due to the distance decreases, intercellular interference increases.

[0025] The object of the present invention is therefore to provide a radio communication device and a method for generating a reference signal that will reduce intercellular interference within and outside the CoMP assembly.

Solution to the problem [0026] The invention is defined by the subject matter of the independent claims. Preferred embodiments are claimed in the dependent claims.

[0027] In an example to assist in understanding the present invention, the radio communications device uses a configuration having: a CoMP mode setting section that sets one of the CoMPs in which CoMP transmitting and receiving (coordinated multi-point transmitting and receiving) is used to perform the transmitting and receiving in many cells in a coordinated manner, and a non-CoMP terminal in which CoMP transmission and reception is not used; a hopping pattern calculation section that includes a variety of different hopping patterns for skipping ZC sequence numbers (Zadoffa-Chu) for use as a reference signal, skips ZC sequence numbers according to a hopping pattern compatible with a CoMP terminal or a non-CoMP terminal set by the mode setting section CoMP, and calculates the ZC sequence number; and.

[0028] In the method of generating the reference signal according to the present invention: one of the CoMP terminal is set up, in which CoMP transmitting and receiving (coordinated multi-point transmitting and receiving) is used to perform transmitting and receiving in multiple cells in a coordinated manner, and a non-coordinated terminal CoMP in which CoMP transmission and reception is not used; contains a variety of different skipping patterns for skipping ZC sequence numbers (Zadoff-Chu) for use as a reference signal, skips the ZC sequence number according to the skip pattern according to the set CoMP terminal or the set non-CoMP terminal, and calculates the ZC sequence number; and generate a ZC sequence for use as a reference signal using the calculated ZC sequence number.

Advantageous Effects of the Invention [0029] In accordance with the present invention, it is possible to attenuate intercellular interference in a CoMP syndrome and beyond.

Brief Description of the Drawings [0030] FIG. 1 shows that the transmit signal from the CoMP terminal is received in many cells having different distances.

FIG. 2 shows the output correlation of SRS transmitted by the CoMP terminal and the non-CoMP terminal. FIG. 3 shows ZC sequence numbers for use in cells.

FIG. 4 is a block diagram showing the configuration of a radio terminal device according to embodiment 1 of the present invention.

FIG. 5 is a block diagram showing the base station configuration according to embodiment 1 of the present invention.

FIG. 6 shows a pattern of hopping ZC sequence numbers according to embodiment 1 of the present invention.

FIG. 7 shows the output correlation of SRS transmitted by the CoMP terminal and the non-CoMP terminal according to embodiment 1 of the present invention.

FIG. 8 shows a state in which distances between cells using the same ZC sequence numbers as designed can be maintained.

FIG. 9 depicts another ZC sequence hopping pattern according to embodiment 1 of the present invention.

FIG. 10 depicts a pattern of hopping ZC sequence numbers according to embodiment 2 of the present invention.

FIG. 11 depicts a pattern of hopping ZC sequence numbers according to embodiment 3 of the present invention.

Description of Embodiments [0031] Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(Embodiment 1) [0032] FIG. 4 is a block diagram showing the configuration of a radio terminal device (hereinafter referred to as "terminal") according to embodiment 1 of the present invention. Then using FIG. 4, the configuration of terminal 100 will be described.

[0033] The CoMP mode setting section 101 sets the CoMP mode hopping section 104 to calculate the CoMP mode predetermined by the device in the form of a radio base station (hereinafter referred to as "base station"), i.e. whether terminal 100 performs CoMP transmission and reception ( CoMP terminal), whether terminal 100 does not transmit and receive CoMP (non-CoMP terminal).

[0034] Section 102 of setting the ZC sequence number within the CoMP assembly sets the ZC sequence numbers for the SRS assigned to multiple cells in the CoMP assembly, and passes the result to section 104 for calculating the hopping pattern.

[0035] The section 103 of setting the ZC sequence number in the system sets all ZC sequence numbers for the SRS available in the system, and the result passes to the section 104 calculating the hopping pattern.

[0036] The hopping pattern calculation section 104 calculates the skipping pattern of the ZC sequence numbers according to the CoMP mode set by the CoMP mode setting section 101 and passes the ZC sequence numbers for use in transmission synchronization to the ZC sequence generation section 105 based on the calculated skip pattern. Specifically, when terminal 100 is a CoMP terminal, the ZC sequence number reported by from section 102 setting the sequence number within the CoMP assembly and used within the CoMP assembly is skipped according to the calculated hopping pattern, and thus the ZC sequence number is calculated for use in broadcast synchronization. At the same time as the terminal

100 is a non-CoMP terminal, skipping of all ZC sequence numbers reported by the ZC Sequence Number 103 setting section in the system and available in the system follows the calculated hop pattern and the ZC sequence number is calculated for use in transmission synchronization. The section will also be described in detail below

104 calculating the hopping pattern.

[0037] The ZC sequence generation section 105 generates the ZC sequence for use as the SRS by using the ZC sequence number transmitted from the hopping pattern calculation section 104 and passes the result to the mapping section 106.

[0038] The mapping section 106 maps the ZC sequence for the SRS provided at the output of the section

105 generating the ZC sequence on the frequency band of terminal 100 designated previously by the base station and transmits the mapped ZC sequence to section 107 of the IFFT (inverse fast Fourier transform).

[0039] Section 107 IFFT performs IFFT processing on the ZC sequence provided at the output from the mapping section 106 and provides output the ZC sequence subjected to the IFFT to the section

108 adding CP (cyclic prefix).

[0040] The section 108 of adding CP to the beginning of the signal adds as the CP the same signal as the end portion of the signal delivered at the output of the IFFT section 107 and at the output provides the signal to the section

109 RF broadcasting (radio frequency).

[0041] The RF broadcasting section 109 performs broadcast processing such as C / A conversion, uplift and gain conversion on the output provided from the CP addition section 108, and the broadcasted signal transmits via antenna 110 as SRS.

[0042] FIG. 5 is a block diagram showing the configuration of base station 200 according to embodiment 1 of the present invention. The configuration of the base station 200 is described below using FIG. 5.

[0043] The RF receiving section 202 performs reception processing, such as downward conversion and A / C conversion, relative to the signal received by the antenna 201 and outputs the processed signal to the CP removal section 203.

[0044] The CP removal section 203 removes the CP added at the top of the reception signal provided at the output from the RF reception section 202 and the output provides at the output to the FFT (fast inverse Fourier transform) section.

[0045] The FFT section 204 performs FFT processing on the SRS signal in the time domain provided at the output from the CP removal section 203, converts the result into frequency domain signals, and outputs the transformed frequency domain to the 205 demapping section.

[0046] The demapping section 205 acquires the SRS corresponding to the transmission bandwidth of the desired terminal from the SRS in the frequency domain, which is provided at the output from section 204 FFT, and at the output provides the acquired SRS to the division section 211.

[0047] The CoMP mode setting section 206 sets the CoMP mode hopping calculation section 209 determined by the control section (not shown) and the like, i.e. whether terminal 100 performs CoMP transmission and reception (CoMP terminal) or terminal 100 does not perform transmission and CoMP reception (non-CoMP terminal).

[0048] Section 207 of setting the ZC sequence number within the CoMP assembly sets the ZC sequence numbers for the SRS allocated to multiple cells within the CoMP assembly and the output provides to the output to section 209 of calculating the hopping pattern.

[0049] Section 208 of setting the sequence number in the system sets all ZC sequence numbers for SRS available in the system and the output results to section 209 calculating the hopping pattern.

[0050] The hopping pattern calculation section 209 calculates the hopping pattern of the ZC sequence numbers according to the CoMP mode set by the CoMP mode setting section 206 and based on the calculated hopping pattern at the output provides to the ZC sequence generation section 210 the ZC sequence numbers for use in broadcast signal synchronization from terminal 100. Specifically, when terminal 100 is a CoMP terminal, the ZC sequence number reported from section 207 of setting the ZC sequence number within the CoMP assembly and for use within the CoMP assembly is skipped according to the calculated hopping pattern and thus the ZC sequence number is calculated applications for broadcast synchronization. In turn, if terminal 100 is a non-CoMP terminal, skipping all sequence numbers reported from the sequence number setting section 208 in the system and available in the system follows the calculated hopping pattern, and the ZC sequence number is calculated for use in transmission synchronization.

[0051] Section 206 of setting the CoMP mode, section 207 of setting the ZC sequence number within the CoMP assembly, section 208 of setting the ZC sequence number in the system and section 209 of calculating the hopping pattern correspond to and perform the same function as section 101 of setting the CoMP mode, section 102 of setting the ZC sequence number within the CoMP assembly, section 103 of setting the ZC sequence number in the system and section 104 of calculating the hopping pattern at terminal 100 shown in FIG. 4.

[0052] As described above, the hopping pattern calculation section 209 calculates the hopping pattern according to whether the SRS sending terminal 100 is a CoMP terminal or a non-CoMP terminal, and determines the ZC sequence number when synchronizing the transmission of the SRS terminal 100.

[0053] The ZC sequence generation section 210 generates the ZC sequence for the SRS transmitted by terminal 100 using the ZC sequence number provided at the output from the hopping pattern calculation section 209 and the output at the output provides to the division section 211.

[0054] The split section 211 divides the SRS provided from the mapping section 205 by the ZC sequence for the SRS provided from the ZC sequence generation section 210, and the result of the split provides output to IFFT section 212.

IFFT section 212 performs IFFT processing on the split result provided from section 211 and outputs IFFT processed signal (equivalent to delay profile) to masking processing section 213.

[0055] The masking processing section 213 acquires the interval in which the correlation value of the desired CS-ZC sequence is contained, that is, acquires the correlation value in the CS detection window by performing masking processing on the SRS provided from section 212 of the IFFT and provides the obtained correlation value at the output to section 214 DFT (discrete Fourier transform). [0056] Section 214 DFT performs DFT processing on the correlation values ​​provided from masking processing section 213 and output to section 215 CQI estimation the correlation values ​​subjected to DFT processing. Here, the DFT processed signal and provided from DFT section 214 represents the frequency response of the channel.

[0057] CQI estimation section 215 estimates (channel quality estimation) SINR for each predetermined band based on the signal representing the frequency response provided from DFT section 214 and outputs an estimated CQI value corresponding to the estimated SINR.

[0058] Next, the operation of the section 104 for calculating the hopping pattern of terminal 100 shown in FIG. 4. Section 209 calculating the hopping pattern of the base station 200 performs the same operation as section 104 calculating the hopping pattern, so the detailed description will be omitted.

[0059] Accordingly, whether terminal 100 is a CoMP terminal or a non-CoMP terminal, section 104 of calculating the hopping pattern switches the hopping pattern of the ZC sequence numbers for the SRS and specifies the ZC sequence number for the SRS for use in transmission synchronization.

[0060] When the terminal 100 is a non-CoMP terminal, the hopping pattern calculation section 104 first calculates the ZC UN sequence number (t) for the SRS of the non-CoMP terminal as shown in equation 1, using the hopping function () previously defined in the system.

UN (t) = hopping (NYU_nit + t) · · (Równame 1)

N is the cell number here, t is the subframe number of the transmission, and u ^ init is the initial value of the ZC sequence number for SRS in cell N. For each subframe, this hop function changes the numbers between all ZC sequence numbers available in the system. However, the ZC uN (t) sequence number for the SRS of a non-CoMP terminal may be constant and not change at each sub-frame.

[0061] When the terminal 100 is a CoMP terminal, the hopping pattern calculation section 104 skips the ZC sequence number that the non-CoMP terminal uses within the CoMP assembly. For example, when the CoMP assembly consists of three cells, cell 1, cell 2 and cell 3, section 104 of calculating the hopping pattern calculates the ZC ueoMP (t) sequence number for the CoMP terminal SRS as shown in equation 2.

· ^{(Equation 2)}

In equation 2 (t) mod (3) means the remainder of the division of the sub-frame number t transmitting by the number of cells 3. It is assumed here that the sub-frame number t is changed in the following order t # 0> t # 1> t # 2> t # 3> t # 4. In this case, the ZC sequence number ueoMP (t) for the SRS of the CoMP terminal to be used for synchronization of transmission of each transmission sub-frame is changed as follows: ui (0)> u2 (1)> u3 (2)> ui (3)> u2 ( 4) according to equation 2. The change is made between ZC sequence numbers for use in cells # 1, 2 and 3 within the CoMP assembly.

[0062] FIG. 6 represents this state. In FIG. 6, respectively, the sequence number ZC 1 (ZC # 1) is allocated to cell 1 within the CoMP assembly, the sequence number ZC 2 (ZC # 2) is allocated to cell 2, and the sequence number ZC 3 (ZC # 3) is allocated to cell 3. The ZC sequence number for the SRS of the CoMP terminal, the number to be used for the t number of the transmission subframe at transmission synchronization of t # 0, goes to ZC # 1, and the CoMP terminal and the nonCoMP terminal that is in cell 1 multiplex the ZC ZC # 1 sequence with various CSZC sequences.

[0063] Then the ZC sequence number for the SRS of the CoMP terminal, the number to be used for the transmission subframe with the number t in transmission synchronization equal t # 1, jumps from ZC # 1 to ZC # 2, and the CoMP terminal and the non-CoMP terminal, which being in cell 2, multiplex the ZC ZC # 2 sequence with different CSZC sequences.

[0064] Next, the ZC sequence number for the SRS of the CoMP terminal, the number to use the case of the transmission subframe with the number t at transmission synchronization equal t # 2, jumps from ZC # 2 to ZC # 3, and the CoMP terminal and the non-CoMP terminal, which is in cell 3, they multiplex the ZC ZC # 2 sequence with different CSZC sequences.

[0065] The ZC sequence number for the SRS of the CoMP terminal, the number to use the case of the transmission subframe with the number t in transmission synchronization equal t # 3, jumps from ZC # 3 to ZC # 1, thereby returning to the situation when the transmission subframe t number is t # 0.

[0066] By skipping the ZC sequence numbers used by the CoMP terminal in the ZC sequence range for use within the CoMP assembly, it is possible to prevent strong interference occurring when the CoMP terminal and non-CoMP terminal use the same ZC sequence in one cell. This is achieved by skipping the ZC sequence numbers that the CoMP terminal uses and the sequence numbers that the nonCoMP terminal uses, by using different hopping patterns and by making the ZC sequence hopping interval at the skip shorter than the transmission synchronization update update interval.

[0067] When the CoMP terminal and the non-CoMP terminal use different ZC sequence numbers, the interference components become cross-correlated at a certain level, and therefore it is possible to limit the deterioration of CQI estimation accuracy even when the reception synchronization is delayed, as shown in FIG. 7. In addition, a certain level of interference components makes it possible to perform compensation calculations on the receiver side and thus prevent deterioration of the accuracy of the CQI estimation.

[0068] As shown in FIG. 8, the CoMP terminal uses the ZC sequence within the CoMP assembly, and thus does not cause intercellular interference in the terminal outside the CoMP assembly. This means that the distance between cells using the same ZC sequence number can be maintained at the planned level, so that it is possible to prevent the increase of intercellular interference between the CoMP terminal and the terminal outside the CoMP assembly.

Accordingly, according to embodiment 1, by hopping the ZC sequence number used by the CoMP terminal in the ZC sequence range for use within the CoMP assembly, it is possible to prevent strong interference when the CoMP terminal and the non-CoMP terminal use this the same ZC sequence in one cell. In addition, the CoMP terminal uses the ZC sequence within the CoMP assembly, it is possible to prevent the increase of intercellular interference between the CoMP terminal and the terminal outside the CoMP assembly.

[0070] Although the present embodiment describes a case in which a ZC sequence assigned to a cell within a CoMP assembly is constant, the ZC sequence number assigned to a cell within a CoMP assembly can be skipped as shown in FIG. 9. However, in this case it is necessary to set the ZC sequence hopping pattern in a given cell other than the ZC sequence hopping pattern used by the CoMP terminal.

[0071] By pre-defining the ZC sequence hopping pattern for the SRS, the number used by the CoMP terminal, it is possible to limit the signaling from the base station to the terminal. That is, the initial value (= uN_init) for each cell within the CoMP assembly and the hopping pattern for each cell (e.g., in ascending order of cell numbers) must be reported to the terminal only once, and therefore signaling for each SRS transmission is not required.

[0072] ZC sequence hopping patterns used by the CoMP terminal and the non-CoMP terminal may not be regular.

(Embodiment 2) [0073] Because the configuration of the terminal according to embodiment 2 of the present invention is similar to the configuration of embodiment 1 shown on FiG. 4 and differs only in the function of the hopping pattern calculation section 104, the hopping pattern calculation section 104 will be described using FIG. 4. Furthermore, because the configuration of the base station in embodiment 2 of the present invention is similar to the configuration of embodiment 1 shown in FIG. 5 and only differs by the function of section 209 calculating the hopping pattern, which is the same as section 104 calculating the terminal hopping pattern, the detailed description will be omitted.

[0074] Depending on whether the terminal 100 is a CoMP terminal or a non-CoMP terminal, the hopping pattern calculation section 104 switches ZC sequence hopping patterns for SRS and specifies the ZC sequence number for SRS that should be used in transmit synchronization.

[0075] When terminal 100 is a non-CoMP terminal, as in embodiment 1, the hopping pattern calculation section 104 calculates the sequence number ZC uN (t) for the SRS of the non-CoMP terminal according to equation 1.

[0076] At the same time, when terminal 100 is a CoMP terminal, the hopping pattern calculation section 104 skips the ZC sequence number for use by the non-CoMP terminal outside of the CoMP assembly. For example, when the CoMP assembly consists of three cells, cell 1, cell 2 and cell 3, section 104 calculating the hopping pattern calculates the ZC uCoMP (t) sequence number for the CoMP terminal SRS as shown in equation 3.

ucoMp (t)^{u =}((») Mod (27) +4) (t) ^ sname ³⁾

In equation 3, the number 27 is the number obtained by subtracting 3, i.e. the number of cells in the CoMP assembly, from 30, i.e. the number of all ZC sequence numbers available throughout the system, i.e. the number of ZC sequence numbers to be used outside the CoMP assembly. Here it is assumed to change the t number of the transmission subframe in the order t # 0> t # 1> t # 2> t # 3> t # 4. In this case, the ZC uCoMP (t) sequence number for the SRS of the CoMP terminal, the number to be used for synchronization of transmission of each broadcasting sub-branch, is as follows. u4 (0) -> u5 (1) -> u6 (2)> u7 (3)> us (4), according to equation 3. The change is made between the ZC sequence numbers used outside the CoMP.

[0077] FIG. 10 presents this condition. In FIG. 10, in transmission synchronization, when the transmission subframe number t is t # 0, the ZC sequence number for the SRS of the CoMP terminal uses ZC # 4, the ZC 1 sequence number (ZC # 1) is appropriately assigned to cell 1 within the CoMP assembly, sequence number ZC 2 (ZC # 2) is assigned to cell 2 and the ZC 3 sequence number (ZC # 3) is assigned to cell 3.

[0078] Then, when during transmission synchronization the number of the transmission sub-frame t changes from t # 0 to t # 1, the ZC sequence number for the SRS of the CoMP terminal jumps from ZC # 4 to ZC # 7, cell 1 jumps from ZC # 1 to ZC # 4, cell 2 jumps from ZC # 2 to ZC # 5, and cell 3 jumps from ZC # 3 to ZC # 6.

[0079] Then, when the transmission subframe number t changes from t # 1 to t # 2 during transmission synchronization, the CoC terminal ZC sequence number SRS jumps from ZC # 7 to ZC # 10, cell 1 jumps from ZC # 4 to ZC # 7, cell 2 jumps from ZC # 5 to ZC # 8, and cell 3 jumps from ZC # 6 to ZC # 9.

[0080] Then, when during transmission synchronization the transmission subframe number t changes from t # 2 to t # 3, the ZC sequence number for the SRS of the CoMP terminal jumps from ZC # 10 to ZC # 13, cell 1 jumps from ZC # 7 to ZC # 10, cell 2 jumps from ZC # 8 to ZC # 11, and cell 3 jumps from ZC # 9 to ZC # 12.

[0081] Thus, according to embodiment 2, when jumping over the sequence number used by the CoMP terminal in the ZC sequence range for use outside the CoMP assembly, the ZC sequence number for the SRS of the CoMP terminal and the ZC sequence number for the SRS of the nonCoMP terminal always differ within the CoMP assembly. It is thus possible to prevent strong interference in the event that the CoMP terminal and the non-CoMP terminal use the same ZC sequence.

[0082] Furthermore, the non-CoMP terminal within the CoMP assembly skips the ZC sequence number used by the CoMP terminal according to a different pattern, so it is possible to randomize interference between a non-CoMP terminal outside the CoMP assembly, a non-CoMP terminal using the same ZC sequence number what is the one within the CoMP team, and the non-CoMP terminal within the CoMP team, thereby reducing the deterioration in accuracy of the CQI estimation caused by interference.

[0083] Although in the present embodiment, a case has been described in which the hopping patterns of the ZC sequence numbers used by the CoMP terminal and the nonCoMP terminal are regular, these hopping patterns need not be regular.

(Embodiment 3) [0084] In Embodiment 3 of the present invention, a case will be described in which a cell comprises multiple CoMP terminals and various CoMP assemblies comprise multiple CoMP terminals. In this case, while providing the ZC sequence hopping pattern for the SRS of each CoMP terminal, the ZC sequence numbers for the SRS of each of the CoMP terminals in the cell are different. It is therefore not possible to make SRS used by many CoMP terminals orthogonal in the CDM (code domain), so the accuracy of CQI estimation is deteriorating. When multiplexing SRS for many CoMP terminals using TDM (time domain) or FDM (frequency domain), SRS orthogonality can prevent CQI estimation deterioration, but SRS transmission time in the cell and overhead of frequency resources increases.

[0085] In the following, for a case where many CoMPs are included in different CoMPs, a method will be described for preventing deterioration of CQI estimation accuracy, shortening SRS transmission time in a cell, and reducing overhead of frequency resources.

[0086] The terminal configuration in accordance with embodiment 3 of the present invention is similar to the configuration shown in FIG. 4 of embodiment 1 and differs only in the function of the section number 102 of setting the sequence number within the CoMP assembly, therefore various functions of the same will be described using FIG. 4. In addition, since the base station configuration in accordance with embodiment 3 of the present invention is similar to the configuration of embodiment 1 shown in FIG. 5 and only differs by the function of section 207 of setting the sequence number within the CoMP assembly, which is the same as section 207 of setting the sequence number within the CoMP assembly of the terminal, the detailed description will be omitted.

[0087] Section 102 of setting the sequence number within the CoMP assembly sets the ZC sequence number for the SRS, i.e. the number to be used in all cells that make up the CoMP assembly, to which many CoMP terminals present in the cell belong, and the output of the setting provides output to section 104 calculating the hopping pattern.

[0088] For example, it is assumed that two CoMP terminals 1 and 2 are present in a cell, the CoMP assembly to which CoMP 1 belongs is formed by cells 1 and 2, and the CoMP assembly to which CoMP 2 belongs is formed by cells 2 and 3. That is, it is assumed that CoMP teams differ in configurations between CoMP 1 and 2 terminals. In this case, section 102 of setting the sequence number within a CoMP assembly sets all the cells that make up the CoMP assemblies, which include respectively many CoMP terminals, i.e. the combined CoMP assembled by cells from 1 to

3. Then, section 102 of setting the sequence number within the CoMP assembly outputs ZC sequence numbers for SRS cells 1 to 3 to section 104 for calculating the hopping pattern.

[0089] FIG. 11 presents this condition. Although FIG. 11 has the same hopping pattern as shown in FIG. 9, FIG. 11 differs from FIG. 9 in that two CoMP terminals 1 and 2 use the same ZC sequence. In addition, FIG. 11 differs from FIG. 9 in that the CoMP assembly, to which the CoMP 1 terminal belongs, is formed by cells 1 and 2, and the CoMP assembly, to which the CoMP 2 terminal belongs, is formed by cells 2 and 3, and the ZC sequence number hopping occurs between the cells forming the CoMP assemblies to which you need many CoMP terminals.

[0090] Thus, according to embodiment 3, when many CoMP terminals present in a given cell are contained in different CoMP units, respectively, the ZC sequence number for use by the CoMP terminal is skipped in the range of ZC sequences for use in all cells forming CoMP units which many CoMP terminals belong to. Therefore, it is possible for the ZC sequence numbers used by many CoMP terminals present in a given cell to be the same, so that the CDM (code axis) can orthogonalize the SRS used by many CoMP terminals. In this way it is possible to prevent deterioration of the accuracy of the CQI estimation. In addition, there is no need to multiplex multiple CoMP terminals from SRS using TDM or FDM, so that it is possible to shorten SRS transmission time and reduce overhead of frequency resources.

[0091] The CoMP syndrome in the above embodiments may be referred to as "cooperative CoMP syndrome". In addition, the CoMP may be a cell group (= CoMP measuring unit) to which the terminal reports channel status for CoMP transmission and reception.

[0092] Although in the above embodiments, an SRS transmitted by a terminal, for which UL CoMP is used, is described for example, the present invention is not limited to this. For example, SRS can be used to provide CSI (channel status information) channel state information) to implement adaptive control (resource allocation, MCS control, pre-coding vector update) with CoMP downlink in TDD (Time Division Duplex). Thus, the essential requirement is that one terminal should transmit SRS to many cells at the same time.

[0093] The ZC sequence number in the above embodiments can be replaced by "ZC sequence group number".

[0094] Although the above embodiments describe a case in which hopping the ZC sequence number of a CoMP terminal and the ZC sequence number of a non-CoMP terminal occurs with the same switching period, it is also possible to hop over these ZC sequence numbers with different switching periods. For example, it is assumed that the switching period of a ZC sequence of a non-CoMP terminal is T 1 [ms] and the switching period of a ZC sequence of a CoMP terminal is T2 [ms] (it should be noted that T2 [ms]> T1 [ms], including T2 infinite (that is without switching)).

[0095] With these measures, within the CoMP assembly, strong interference can be prevented in one cell when the CoMP terminal and non-CoMP terminal use the same ZC sequence. Here, when the switching period of the ZC sequence of one terminal is infinite, only the ZC sequence of the other terminal is switched, and thus interference with a non-CoMP terminal outside of a CoMP assembly using the same ZC sequence number can be randomized.

[0096] Although an example is described in the above embodiments in which the present invention is implemented in hardware, the present invention may be implemented with software.

[0097] Furthermore, each function block used in the description of each of the aforementioned embodiments may generally be implemented as an LSI as an integrated circuit. They can be single chips or they can be partly or completely contained in one chip. The term "LSI" is adopted here, but it can also be referred to as "IC", "system LSI", "super LSI" or "ultra LSI", depending on different integration scales.

[0098] Furthermore, the circuit integration method is not limited to LSI, and implementation using dedicated circuits or general-purpose processors is also possible. After creating the LSI, it is also possible to use FPGA (directly programmable gate array) or a reconfigurable processor in which the connections and settings of the LSI circuit cells can be restored.

[0099] Furthermore, if as a result of the progress of the semiconductor technology, circuit integration technology or other derivative technology emerges that replaces LSI, it will of course be possible to implement function block integration using this technology. The use of biotechnology is also possible.

[0100] Although the present invention has been described above for embodiments using antennas, the present invention applies equally to antenna ports. [0101] The term "antenna port" refers to a theoretical antenna consisting of one or more physical antennas. Thus, the term "antenna port" need not necessarily mean one physical antenna, but may, for example, mean an antenna array formed of multiple antennas.

[0102] For example, 3 GPP LTE does not define how many physical antennas an antenna port consists of, but defines that the antenna port is the smallest unit for transmitting various reference signals at a base station.

[0103] Furthermore, the antenna port may be defined as the smallest unit for multiplying the precoding vector as a weight.

Industrial applications [0104] The radio communication device and the method of generating the reference signal according to the present invention can be used for example in a mobile communication system such as LTE-Advanced system.

List of reference symbols [0105]

101.206 section for setting CoMP mode

102, 207 section for setting the ZC sequence number within a CoMP assembly

103, 208 section for setting the ZC sequence number in the system

104, 209 section for calculating the hopping pattern

105, 210 section generating ZC sequences

106 mapping section

107, 212 section IFFT

108 adding CP section

109 RF broadcast section

110, 210 antenna

202 RF reception section

203 CP removal section

204 FFT section

205 demapping section

211 division section

213 masking processing section

214 DFT section

215 CQI estimation section [0106] The first example is a radio communication device comprising a CoMP mode setting section configured to set up one of the CoMP (coordinated multi-point transmit and receive) on which CoMP is used to perform the transmission and reception among multiple cells in a coordinated manner, and a non-CoMP terminal to which CoMP is not applied, a hopping pattern calculation section configured, to include many different hopping patterns for skipping the ZC sequence number (Zadoff-Chu) used as a reference signal, and calculating the ZC sequence number by hopping the ZC sequence number with the hopping pattern compatible with the terminal

CoMP or a non-CoMP terminal set by the CoMP mode setting section, and the ZC sequence generation section that generates the ZC sequence using the calculated ZC sequence number.

[0107] A second example is a radio communication device according to the first example, in which the hop pattern calculation section calculates the ZC sequence number by hopping the ZC sequence number used inside a CoMP assembly, grouping multiple cells, to perform the transmission and reception in a coordinated manner when the device radio communication is set as a CoMP terminal through the CoMP mode setting section.

[0108] A third example is a radio communication device according to the first example, in which the hopping pattern calculation section calculates the ZC sequence number by hopping the ZC sequence number used outside the CoMP grouping a plurality of cells to perform the transmission and reception in a coordinated manner when the device radio communication is set as a CoMP terminal through the CoMP mode setting section.

[0109] A fourth example is a radio communication device according to the second example, wherein the CoMP is configured by all cells configuring the CoMP, to which many CoMP terminals present in the cell belong.

[0110] A fifth example is a radio communication device according to the third example, in which the CoMP is configured by all cells configuring the Co MP, to which many CoMP terminals present in the cell belong.

[0111] A sixth example is a method of generating a reference signal comprising setting one of the CoMP terminal (coordinated multi-point sending and receiving, enabling many different hopping patterns to skip the ZC (Zadoffa-Chu) sequence number used as the reference signal, calculating the ZC sequence number by skipping ZC sequence number with a hopping pattern compatible with the CoMP terminal set or the non-CoMP terminal set and generating the ZC sequence used for the reference signal using the calculated ZC sequence number.

Sun Patent Trust Representative:

PL-PAT-2012-2218

EP 3 337 217 B1