Transmitting device, wireless communication system, transmission method, control circuit, and storage medium

Abstract

A base station in a wireless communication system comprising multiple base stations has a transmitting device (100) which modulates a transmission bit sequence to generate a modulation symbol, a differential block coding device (11) which differentially blocks encodes the modulation symbol to generate a differential block coded signal, and a precoding device (12) which performs a precoding process including phase rotation on the differential block coded signal. The precoding device (12) phase-rotates the differential block coded signal by a different amount of phase rotation than the phase rotation included in the precoding process performed by the precoding device of a transmitting device of another base station adjacent to the base station where the self-transmitting device is installed.

Description

[Technical Field]

[0001] This disclosure relates to a transmitting device, a wireless communication system, a transmitting method, a control circuit, and a storage medium. [Background technology]

[0002] In wireless communication, diversity technology is sometimes applied to prevent a decrease in communication performance due to fading. For example, in spatiotemporal block coding wireless communication, which is a type of transmit diversity, the transmitting device performs spatiotemporal block coding on the transmission sequence to generate multiple orthogonal sequences. The transmitting device then transmits these multiple sequences using different antennas. In spatiotemporal block coding wireless communication, full diversity gain can be obtained at the receiving end.

[0003] In spatiotemporal block coding wireless communication (hereinafter simply referred to as "spatiotemporal block coding"), multiple symbols are treated as a single transmission block. Generally, in spatiotemporal block coding, the number of antennas is associated with the number of symbols treated as a single transmission block. For example, in spatiotemporal block coding with two antennas, two symbols are treated as one transmission block. A receiver in spatiotemporal block coding needs to estimate the transmission path information in order to demodulate the received spatiotemporal block coding symbols.

[0004] Furthermore, there is a differential block coding scheme that performs differential coding on a per-transmission block basis in spatiotemporal block coding, which allows for the use of diversity effects through spatiotemporal block coding and eliminates the need to estimate transmission path information. For example, in a differential block coding scheme with two antennas, the transmitting device generates a 2x2 matrix with two symbols as one transmission block and performs differential coding between the matrices of two consecutive transmission blocks. The receiving device generates a 2x2 matrix with the two received symbols and performs demodulation by performing differential decoding between the two matrices (see Non-Patent Literature 1). [Prior art documents]

Non-Patent Document

[0005]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When constructing a wireless communication system by installing a plurality of base stations, it is desirable to arrange each base station so that an area where the base station and the mobile station cannot communicate does not occur. In this case, at a location where communication areas, which are areas where each base station and the mobile station can communicate, overlap, the same signal at the same frequency transmitted from each base station reaches the mobile station in a state where they are combined with equal power and opposite phases. That is, there is a problem that so-called beat interference occurs, in which the power of the signal received by the mobile station decreases, and the communication performance deteriorates.

[0007] The present disclosure has been made in view of the above, and an object thereof is to obtain a transmission device capable of suppressing the occurrence of beat interference in a wireless communication system.

Means for Solving the Problems

[0008] To solve the above-mentioned problems and achieve the objective, this disclosure provides a transmitting device for a base station of a wireless communication system comprising a plurality of base stations, comprising: a modulation unit that modulates a transmission bit sequence to generate a modulation symbol; a differential block coding unit that differentially blocks encodes the modulation symbol to generate a differential block coded signal; and a precoding unit that performs a precoding process including phase rotation on the differential block coded signal, wherein the precoding unit uses a phase rotation amount different from the phase rotation included in the precoding process performed by the precoding unit of a transmitting device provided by another base station adjacent to the base station where the self-transmitting device is installed. ,difference Dynamic block coding signal At set intervals Phase rotation The modulation symbol unit is defined as the resolution of a specified time. It is characterized by the following. [Effects of the Invention]

[0009] The transmitting device described herein has the effect of suppressing beat interference in wireless communication systems. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows an example configuration of a wireless communication system according to Embodiment 1. [Figure 2] This figure shows an example of the configuration of the transmitting device included in the base station according to Embodiment 1. [Figure 3] A flowchart illustrating an example of the operation of the transmitting device provided in the base station according to Embodiment 1. [Figure 4] This figure shows an example of precoding processing by the precoding unit of the transmitting device according to Embodiment 1. [Figure 5] This figure shows an example configuration of a wireless communication system according to Embodiment 2. [Figure 6] This figure shows an example of the configuration of a processing circuit when the processing circuit of the transmitting device according to Embodiments 1 and 2 is implemented using a processor and memory. [Figure 7]This figure shows an example of a processing circuit when the processing circuit of the transmitting device according to Embodiments 1 and 2 is configured with dedicated hardware. [Modes for carrying out the invention]

[0011] The following describes in detail, with reference to the drawings, the transmitting device, wireless communication system, transmitting method, control circuit, and storage medium according to embodiments of the present disclosure.

[0012] Embodiment 1. Figure 1 shows an example configuration of a wireless communication system 200 according to Embodiment 1. The wireless communication system 200 according to this embodiment includes a control device 1 for controlling a group of base stations, a base station 2 covering a communication area 2a, a base station 3 covering a communication area 3a, and a mobile station 4.

[0013] In the wireless communication system 200 shown in Figure 1, the frequency of the signal transmitted by base station 2 and the frequency of the signal transmitted by base station 3 are the same. Also, there is a partial overlap between the communication area 2a of base station 2 and the communication area 3a of base station 3. As an example, Figure 1 shows a case where a mobile station 4 is located in an area where communication areas 2a and 3a overlap, and the mobile station 4 can communicate with both base station 2 and base station 3.

[0014] Base stations 2 and 3, based on control from control device 1, wirelessly transmit a sequence of transmit bits, which is information received from control device 1. Base stations 2 and 3 are assumed to receive the same sequence of transmit bits from control device 1 at the same time.

[0015] Mobile station 4 receives information transmitted from base stations 2 and 3.

[0016] Here, base stations 2 and 3 transmit signals in synchronization. For example, base stations 2 and 3 transmit signals in synchronization based on GPS (Global Positioning System) time information. However, the method of synchronization between base stations 2 and 3 is not limited to this. For example, control device 1 may transmit a synchronization signal to base stations 2 and 3, and base stations 2 and 3 may transmit signals in synchronization based on this signal.

[0017] Under the conditions described above, if base stations 2 and 3 transmit the same information as signals, at the location of mobile station 4 shown in Figure 1, the transmitted signals from base station 2 and base station 3 are attenuated by the same amount due to radio wave propagation, resulting in the same received power at the same time and being received at the antenna terminal of mobile station 4. This phenomenon, known as beat interference, occurs.

[0018] In Figure 1, the wireless communication system 200 is configured to include two base stations (base station 2 and base station 3) and one mobile station 4, but the number of base stations and mobile stations is not limited to this.

[0019] Figure 2 shows an example configuration of the transmitting device 100 provided by base stations 2 and 3 according to Embodiment 1. As shown in Figure 2, the transmitting device 100 according to this embodiment includes a modulation unit 10 that maps a transmission bit sequence as modulation symbols onto the complex plane, a differential block coding unit 11 that performs differential block coding on the modulation symbols and generates a differential block coded signal, and a precoding unit 12 that performs precoding processing with weighting and phase rotation on the differential block coded signal generated by the differential block coding unit 11. The transmitting device 100 also includes a transmission filter unit 13a that performs filtering processing for bandwidth limiting corresponding to a first transmitting antenna on the differential block coded signal precoded by the precoding unit 12, a transmission filter unit 13b that performs filtering processing for bandwidth limiting corresponding to a second transmitting antenna, a digital-to-analog conversion unit 14a that performs digital-to-analog conversion on the signal bandwidth limited by the transmission filter unit 13a, and a digital-to-analog conversion unit 14b that performs digital-to-analog conversion on the signal bandwidth limited by the transmission filter unit 13b. Furthermore, the transmitting device 100 includes a high-frequency unit 15a that modulates the transmission signal, which has been converted to analog by the digital-to-analog conversion unit 14a, to the carrier frequency; a high-frequency unit 15b that modulates the transmission signal, which has been converted to analog by the digital-to-analog conversion unit 14b, to the carrier frequency; a transmitting antenna 16a that transmits the high-frequency signal output from the high-frequency unit 15a; and a transmitting antenna 16b that transmits the high-frequency signal output from the high-frequency unit 15b.

[0020] Next, the processing of the precoding unit 12 of the transmitting device 100 will be described. The precoding unit 12 performs the precoding processing shown in the following equations (1) and (2) on the differential block coded signal generated by the differential block coding unit 11.

[0021] y1(t)=w 11 ·θ1t·x1(t)+w 12 ·θ2t·x2(t) …(1) y²(t)=w 21 ·θ1t·x1(t)+w22 ·θ2t·x2(t) …(2)

[0022] In expressions (1) and (2), y1(t) and y2(t) represent signals corresponding to the first transmission antenna and the second transmission antenna in the output of the precoding unit 12. w 11 , w 12 , w 21 , w 22 are weight coefficients for creating a mixed component of the precoding output between the transmission antennas 16a and 16b. θ1t and θ2t represent phase rotation values of the first transmission antenna and the second transmission antenna. x1(t) and x2(t) represent signals corresponding to the first transmission antenna and the second transmission antenna in the input to the precoding unit 12.

[0023] Here, the weight coefficients w 11 , w 12 , w 21 , w 22 are weight coefficients for mixing and outputting the signal component transmitted from the first transmission antenna and the signal component transmitted from the second transmission antenna, and are set under the constraints of w 11 +w 12 =1 and w 21 +w 22 =1.

[0024] In this embodiment, for simplicity of explanation, w 11 =1, w 12 =0, w 21 =0, w 22 =1, and it is assumed that there is no component mixing between the transmission antennas 16a and 16b, and the following explanation will continue. In this case, the above expressions (1) and (2) are simplified as expressions (3) and (4).

[0025] y1(t)=θ1t·x1(t) …(3) y2(t)=θ2t·x2(t) …(4)

[0026] As shown in equations (3) and (4), the precoding process by the precoding unit 12 is a process that applies a phase rotation at fixed time intervals t. The resolution of t may be the modulation symbol unit before differential block coding, a finer resolution (e.g., sample unit), or a coarser resolution (e.g., every block, every two blocks, etc. of differential block coding). In other words, the phase rotation may be applied in units of modulation symbols before differential block coding, in units of samples, or in units that are integer multiples of the blocks on which differential block coding is performed.

[0027] The y1(t) corresponding to the first transmitting antennas of base station 2 and base station 3 are respectively y 1a (t) and y 1b (t) The propagation channel information from the first transmitting antennas of base stations 2 and 3 to the receiving antenna of mobile station 4 is h 1a (t) and h 1b If (t) is the case, the received signal r1(t) of the mobile station 4 corresponding to the first transmitting antenna of each base station can be expressed as shown in equation (5).

[0028] r1(t)=h 1a (t)·y 1a (t) + h 1b (t)·y 1b (t) =( h 1a (t)·θ 1a t+h 1b (t)·θ 1b t)·x1(t) …(5)

[0029] Condition without precoding (θ 1a t = θ 1b At t=1), the propagation channel information between each base station and mobile station 4 is in opposite phase (h 1a (t) = -h 1bAt the point in (t), the transmitted information is lost. In environments where propagation channel information changes rapidly over time, the conditions under which the transmitted information is lost are limited. However, for example, if the mobile station 4 is in a stopped state and the propagation channel information is fixed, and the conditions under which the transmitted information is lost occur, a communication interruption will occur.

[0030] On the other hand, when precoding, h 1a (t)·θ 1a t = -h 1b (t)·θ 1b Under the condition t, the transmitted information disappears, but θ 1a t and θ 1b Since t is a value that changes over time due to precoding processing at each base station, it is possible to avoid a state in which transmitted information is continuously lost regardless of the communication environment of mobile station 4.

[0031] If we organize the above similarly for the second transmitting antenna, h 2a (t)·θ 2a t = -h 2b (t)·θ 2b Since the transmission information from the second transmitting antenna disappears under the condition t, when combined with the first transmitting antenna, h 1a (t)·θ 1a t = -h 1b (t)·θ 1b t and h 2a (t)·θ 2a t = -h 2b (t)·θ 2b The goal of precoding is to minimize the occurrence of the condition that results in t, which is the phase rotation value θ. 1a t, θ 1b t, θ 2a t, θ 2b This is the key point when determining t.

[0032] The phase rotation value should be determined with two constraints: the first constraint is that the direction (positive or negative) of the phase rotation should be reversed between transmitting antennas 16a and 16b, and the second constraint is that different phase rotation values ​​should be used for each antenna transmitting the same information between base stations whose communication areas overlap. In other words, the phase rotation value θ1a t, θ 1b t, θ 2a t, θ 2b For t, θ 1a t and θ 1b t means reversing the direction of phase rotation, and θ 2a t and θ 2b t means reversing the direction of phase rotation, and θ 1a t≠θ 1b Let t be θ 2a t≠θ 2b Setting the phase rotation value to t is the condition for setting each phase rotation value.

[0033] In a transmitted signal that has undergone transmit diversity processing using differential block coding, the receiving device (in this embodiment, mobile station 4) can extract information from the received signal as long as the transmitted information from either the first or second transmitting antenna is not lost. Therefore, in order to minimize the chances of the conditions for the loss of transmitted information from the first or second transmitting antenna being the same, it is necessary to reduce the correlation between the signals of transmitting antennas 16a and 16b by "reversing the direction (positive or negative) of phase rotation between transmitting antennas 16a and 16b". In addition, since it is essential that the first and second transmitting antennas do not transmit the same information between base stations, it is important to "use different phase rotation values ​​for each antenna transmitting the same information between adjacent base stations whose communication areas overlap". Note that it is not essential to operate with fixed values ​​for the precoding matrix settings; for example, it is conceivable that the mobile station 4 specifies (notifies) the setting values ​​to each base station and changes them according to the communication environment of mobile station 4. Furthermore, when setting the precoding matrix for each base station, it is acceptable for some base stations not to add any phase rotation values ​​at all.

[0034] Figure 3 is a flowchart showing an example of the operation of the transmitting devices 100 provided by base stations 2 and 3 according to Embodiment 1. Figure 3 shows the processing flow for one communication frame, which is commonly used as a processing unit in a communication system.

[0035] After processing begins, the transmitting device 100 first generates a modulation symbol (step S11). Specifically, the modulation unit 10 generates a modulation symbol by performing modulation processing on the transmission bit sequence, which is the transmission information.

[0036] The transmitting device 100 then performs differential block coding (step S12). Specifically, the differential block coding unit 11 performs differential block coding on the modulation symbols output from the modulation unit 10.

[0037] The transmitting device 100 then updates the precoding matrix and performs precoding (steps S13 and S14). Specifically, the precoding unit 12 updates the precoding matrix and uses the updated precoding matrix to perform precoding on the differential block coded signal output from the differential block coding unit 11.

[0038] Next, the transmitting device 100 performs filtering and other processing on the signal generated by the precoding process before transmitting it (step S15). Specifically, the transmitting filter units 13a and 13b filter the signal output from the precoding unit 12, the digital-to-analog conversion units 14a and 14b perform digital-to-analog conversion, the high-frequency units 15a and 15b perform frequency conversion to the carrier frequency, and the transmitting antennas 16a and 16b transmit the signal at the carrier frequency.

[0039] The transmitting device 100 then checks whether the transmission of one frame has been completed, that is, whether the transmission of the bit sequence for one frame has been completed (step S16). If the transmission of one frame has been completed (step S16: Yes), the process ends. If the transmission of one frame has not been completed (step S16: No), the transmitting device 100 returns to step S11 and repeats the process from steps S11 to S16.

[0040] Note that while Figure 3 shows an example where a series of processes are looped in units of precoding matrix updates (the period during which the precoding matrix is ​​updated), the system is not limited to this configuration. The transmitter 100 may be configured to process each process by each component in a single frame. In other words, even if each process by each component is not looped, it is acceptable as long as the signal processing is equivalent to the process shown in the flowchart of Figure 3.

[0041] Figure 4 shows an example of precoding processing by the precoding unit 12 of the transmitting device 100 according to Embodiment 1. In Figure 4, the image of the precoding processing is represented using the complex plane.

[0042] Figure 4 visually shows examples of phase rotation amounts over three processing times on a complex plane, illustrating the precoding process for each transmitting antenna of base station 2 and base station 3 over three processing times. As shown in Figure 4, the precoding unit 12 performs a phase rotation by a positive phase rotation amount θ1 every processing time for the signal transmitted from the first transmitting antenna of base station 2 (differential block coded signal), and a phase rotation by a negative phase rotation amount θ2 every processing time for the signal transmitted from the second transmitting antenna. Furthermore, the precoding unit 12 performs a phase rotation by a positive phase rotation amount φ1 every processing time for the signal transmitted from the first transmitting antenna of base station 3, which is different from the precoding corresponding to the first transmitting antenna of base station 2, and performs a phase rotation by a negative phase rotation amount φ2 every processing time for the signal transmitted from the second transmitting antenna, which is different from the precoding corresponding to the second transmitting antenna of base station 2.

[0043] In this embodiment, for the sake of simplicity, an example was described in which the communication areas of two base stations partially overlap. However, even when the communication areas of three or more base stations partially overlap, the pre-coding process rotates the transmitted signal by a different phase rotation amount for each base station. For example, if there is an area where one mobile station can communicate simultaneously with three base stations (an area where three communication areas overlap), the transmitting devices 100 of each of the three base stations rotate the transmitted signal by a different phase rotation amount during the pre-coding process. Furthermore, although the case where the transmitting device 100 has two transmitting antennas was described, the number of transmitting antennas may be three or more. Similarly, when the number of transmitting antennas is three or more, the pre-coding process rotates the transmitted signal by a different phase rotation amount for each transmitting antenna.

[0044] As described above, the transmitting device 100 according to this embodiment is applied to two or more base stations that perform the same modulation processing and the same differential block coding processing on the same transmission bit sequence and transmit the transmission signal simultaneously. In the precoding process after differential block coding processing, the phase rotation is performed by a different amount for each antenna that transmits the same transmission signal for each base station. This makes it possible to suppress the occurrence of beat interference in the wireless communication system 200 and improve communication quality. In other words, it is possible to avoid a situation in which the transmission signal is continuously canceled out due to beat interference at the antenna terminal of the mobile station 4 that receives transmission signals from two or more base stations simultaneously, thereby improving communication quality.

[0045] Embodiment 2. Figure 5 shows an example configuration of the wireless communication system 201 according to Embodiment 2.

[0046] The wireless communication system 201 according to this embodiment includes a control device 41 for controlling a group of base stations, a base station 42 covering a communication area 42a, a base station 43 covering a communication area 43a, a base station 44 covering a communication area 44a, a base station 45 covering a communication area 45a, a base station 46 covering a communication area 46a, and a mobile station 47.

[0047] In the wireless communication system 201 shown in Figure 5, the frequencies of the signals transmitted by each of the base stations 42 to 46 are the same. Also, there is some overlap between the communication area 42a of base station 42 and the communication area 43a of base station 43. Similarly, there is some overlap between communication area 43a and communication area 44a, some overlap between communication area 44a and communication area 45a, and some overlap between communication area 45a and communication area 46a. Under these conditions, mobile station 47 moves between areas in the following order: from the communication area 42a of base station 42, to the communication area 43a of base station 43, to the communication area 44a of base station 44, to the communication area 45a of base station 45, and to the communication area 46a of base station 46, or from the communication area 46a of base station 46, to the communication area 45a of base station 45, to the communication area 44a of base station 44, to the communication area 43a of base station 43, and to the communication area 42a of base station 42.

[0048] Communication between the control device 41 and each base station (base stations 42 to 46) is the same as in Embodiment 1. Furthermore, the process and procedure for generating a transmission signal from the transmission bit sequence at each base station are the same as in Embodiment 1. That is, base stations 42 to 46 are equipped with the transmission device 100 described in Embodiment 1. Therefore, a detailed explanation of the operation of the control device 41 and base stations 42 to 46 is omitted.

[0049] Even under conditions such as those shown in this embodiment, where multiple base stations are synchronized and each base station transmits the same transmission information, the phase rotation value of the precoding matrix can be set according to the same constraints as in Embodiment 1, thereby avoiding situations in which beat interference continuously occurs.

[0050] In this embodiment, there are many base stations, and a different phase rotation value for the precoding matrix is ​​set for each base station. However, other setting methods may be applied. Another effective setting method is to set the phase rotation value of the precoding matrix to a different value for adjacent base stations whose communication areas overlap, while setting the same phase rotation value for the next adjacent base station (a non-adjacent base station two base stations away, for example, base station 44 relative to base station 42 in Figure 5). That is, in the wireless communication system 201 shown in Figure 5, base stations 42, 44, and 46 may set the phase rotation value of the precoding matrix to the same value (first value), while base stations 43 and 45 may set the phase rotation value of the precoding matrix to a different value (second value) (base stations 43 and 45 have the same setting value).

[0051] Thus, in this embodiment, the wireless communication system 201 sets different values ​​for the phase rotation amount (phase rotation value of the precoding matrix) in the precoding process for adjacent base stations (base stations whose communication areas partially overlap), and sets the same value for the phase rotation amount in the precoding process for non-adjacent base stations. According to this embodiment, similar to Embodiment 1, by preparing phase rotation values ​​for the precoding matrix for two base stations, it is possible to cover a very wide communication area while obtaining the same effects as Embodiment 1, namely, interference countermeasures against beat interference between base stations.

[0052] Next, the hardware configuration of the transmitting device 100 described above will be explained. In the transmitting device 100, the transmitting filter sections 13a, 13b, the digital-to-analog conversion sections 14a, 14b, the high-frequency sections 15a, 15b, and the transmitting antennas 16a, 16b are implemented by the transmitter. In the transmitting device 100, the other components, namely the modulation section 10, the differential block coding section 11, and the precoding section 12, are implemented by the processing circuit. The processing circuit may be a processor and memory that execute a program stored in memory, or it may be dedicated hardware. The processing circuit is also called a control circuit.

[0053] Figure 6 shows an example configuration of a processing circuit 90 when the processing circuit of the transmitting device 100 according to Embodiments 1 and 2 is implemented using a processor and memory. The processing circuit 90 shown in Figure 6 includes a processor 91 and a memory 92. Each function of the processing circuit 90, which is composed of the processor 91 and the memory 92, is implemented by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 92. In the processing circuit 90, each function is implemented by the processor 91 reading and executing the program stored in the memory 92. In other words, the processing circuit 90 includes a memory 92 for storing a program that will ultimately be executed as a result of the processing of the transmitting device 100. This program can also be said to be a program that causes the transmitting device 100 to execute each function implemented by the processing circuit 90. This program may be provided by a storage medium on which the program is stored, or by other means such as a communication medium.

[0054] Here, the processor 91 is, for example, a CPU (Central Processing Unit), processing unit, arithmetic unit, microprocessor, microcomputer, or DSP (Digital Signal Processor). The memory 92 is, for example, a non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), EEPROM (Registered Trademark) (Electrically EPROM), magnetic disks, flexible disks, optical disks, compact disks, minidiscs, or DVDs (Digital Versatile Discs).

[0055] Figure 7 shows an example of a processing circuit 93 when the processing circuit of the transmitting device 100 according to Embodiments 1 and 2 is configured with dedicated hardware. The processing circuit 93 shown in Figure 7 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. The processing circuit of the transmitting device 100 may be partially implemented with dedicated hardware and partially implemented with software or firmware. In this way, the processing circuit can realize the above-mentioned functions with dedicated hardware, software, firmware, or a combination thereof.

[0056] The configurations shown in the above embodiments are merely examples, and it is possible to combine them with other known technologies, combine different embodiments, and omit or modify parts of the configuration without departing from the gist of the invention. [Explanation of symbols]

[0057] 1,41 Control device, 2,3,42~46 Base station, 2a,3a,42a~46a Communication area, 4,47 Mobile station, 10 Modulation unit, 11 Differential block coding unit, 12 Precoding unit, 13a,13b Transmitting filter unit, 14a,14b Digital-to-analog conversion unit, 15a,15b High-frequency unit, 16a,16b Transmitting antenna, 100 Transmitting device, 200,201 Wireless communication system.

Claims

1. A transmitting device provided by a base station in a wireless communication system comprising multiple base stations, A modulation unit that modulates the transmitted bit sequence to generate a modulation symbol, A differential block coding unit generates a differential block coded signal by differentially coding the aforementioned modulation symbols, A precoding unit that performs precoding processing including phase rotation on the differential block coded signal, Equipped with, The precoding unit rotates the differential block coded signal at predetermined time intervals by a phase rotation amount different from that included in the precoding process performed by the precoding unit of a transmitter located adjacent to the base station where the self-transmitting device is installed, and the resolution of the predetermined time interval is set to the modulation symbol unit. A transmitting device characterized by the following features.

2. A transmitting device provided by a base station in a wireless communication system comprising multiple base stations, A modulation unit that modulates the transmitted bit sequence to generate a modulation symbol, A differential block coding unit generates a differential block coded signal by differentially coding the aforementioned modulation symbols, A precoding unit that performs precoding processing including phase rotation on the differential block coded signal, Equipped with, The precoding unit rotates the differential block coded signal at predetermined time intervals by a phase rotation amount different from that included in the precoding process performed by the precoding unit of the transmitting device of another base station adjacent to the base station where the self-transmitting device is installed, and the resolution of the predetermined time interval is in units of samples. A transmitting device characterized by the following features.

3. The precoding unit rotates the phase of the differential block coded signal transmitted from each of the multiple transmitting antennas by a different phase rotation amount for each transmitting antenna. The transmitting device according to claim 1 or 2.

4. The aforementioned transmitting antenna consists of two antennas. The precoding unit rotates the differential block coded signals transmitted from each transmitting antenna in opposite phase directions. The transmitting device according to feature 3.

5. The precoding process further includes a weighting process that mixes the components of the differential block coded signal transmitted from each of the multiple transmitting antennas. The transmitting device according to claim 1 or 2.

6. The precoding unit changes the amount of phase rotation when it rotates the differential block coded signal according to the specifications from the mobile station. The transmitting device according to claim 1 or 2.

7. A plurality of base stations comprising the transmitting device described in claim 1 or 2, The phase rotation amount included in the precoding process performed by the precoding unit of a transmitting device located at a non-adjacent base station is made the same. A wireless communication system characterized by the following features.

8. A transmission method in which a transmitting device of a base station in a wireless communication system comprising multiple base stations transmits a sequence of transmit bits, A modulation step that modulates the transmitted bit sequence to generate a modulation symbol, A differential block coding step is performed to differentially block encode the aforementioned modulation symbols to generate a differential block coded signal. A precoding step in which a precoding process including phase rotation is performed on the differential block coded signal, Includes, In the precoding step, the differential block coded signal is phase-rotated at predetermined time intervals by a phase rotation amount different from that included in the precoding process performed by the transmitting equipment of another base station adjacent to the base station where the self-transmitting equipment is installed, and the resolution of the predetermined time interval is set to the modulation symbol unit. A transmission method characterized by the following:

9. A transmission method in which a transmitting device of a base station in a wireless communication system comprising multiple base stations transmits a sequence of transmit bits, A modulation step that modulates the transmitted bit sequence to generate a modulation symbol, A differential block coding step is performed to differentially block encode the aforementioned modulation symbols to generate a differential block coded signal. A precoding step in which a precoding process including phase rotation is performed on the differential block coded signal, Includes, In the precoding step, the differential block coded signal is phase-rotated at predetermined time intervals by a phase rotation amount different from that included in the precoding process performed by the transmitting equipment of another base station adjacent to the base station where the self-transmitting equipment is installed, and the resolution of the predetermined time interval is in units of samples. A transmission method characterized by the following:

10. A control circuit comprising a transmitting device of a base station in a wireless communication system comprising multiple base stations, A modulation step that modulates the transmitted bit sequence to generate a modulation symbol, A differential block coding step is performed to differentially block encode the aforementioned modulation symbols to generate a differential block coded signal. A precoding step in which a precoding process including phase rotation is performed on the differential block coded signal, Execute, In the precoding step, the differential block coded signal is phase-rotated at predetermined time intervals by a phase rotation amount different from that included in the precoding process performed by the transmitting equipment of another base station adjacent to the base station where the self-transmitting equipment is installed, and the resolution of the predetermined time interval is set to the modulation symbol unit. A control circuit characterized by the following features.

11. A control circuit comprising a transmitting device of a base station in a wireless communication system comprising multiple base stations, A modulation step that modulates the transmitted bit sequence to generate a modulation symbol, A differential block coding step is performed to differentially block encode the aforementioned modulation symbols to generate a differential block coded signal. A precoding step in which a precoding process including phase rotation is performed on the differential block coded signal, Execute, In the precoding step, the differential block coded signal is phase-rotated at predetermined time intervals by a phase rotation amount different from that included in the precoding process performed by the transmitting equipment of another base station adjacent to the base station where the self-transmitting equipment is installed, and the resolution of the predetermined time interval is in units of samples. A control circuit characterized by the following features.

12. A storage medium for storing a program executed by a control circuit that constitutes a transmitting device of a base station in a wireless communication system comprising multiple base stations, The aforementioned program, A modulation step that modulates the transmitted bit sequence to generate a modulation symbol, A differential block coding step is performed to differentially block encode the aforementioned modulation symbols to generate a differential block coded signal. A precoding step in which a precoding process including phase rotation is performed on the differential block coded signal, The control circuit is made to execute the above, In the precoding step, the differential block coded signal is phase-rotated at predetermined time intervals by a phase rotation amount different from that included in the precoding process performed by the transmitting equipment of another base station adjacent to the base station where the self-transmitting equipment is installed, and the resolution of the predetermined time interval is set to the modulation symbol unit. A storage medium characterized by the following features.

13. A storage medium for storing a program executed by a control circuit that constitutes a transmitting device of a base station in a wireless communication system comprising multiple base stations, The aforementioned program, A modulation step that modulates the transmitted bit sequence to generate a modulation symbol, A differential block coding step is performed to differentially block encode the aforementioned modulation symbols to generate a differential block coded signal. A precoding step in which a precoding process including phase rotation is performed on the differential block coded signal, The control circuit is made to execute the above, In the precoding step, the differential block coded signal is phase-rotated at predetermined time intervals by a phase rotation amount different from that included in the precoding process performed by the transmitting equipment of another base station adjacent to the base station where the self-transmitting equipment is installed, and the resolution of the predetermined time interval is in units of samples. A storage medium characterized by the following features.

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