WO2015162771A1

WO2015162771A1 - Wireless communication system

Info

Publication number: WO2015162771A1
Application number: PCT/JP2014/061647
Authority: WO
Inventors: 正裕青野; 武井　健; 大倉　敬規
Original assignee: 株式会社日立製作所
Priority date: 2014-04-25
Filing date: 2014-04-25
Publication date: 2015-10-29

Abstract

Provided is a wireless communication system which can decode without needing to synchronize the codes. This wireless communication system performs communication using multiple code pairs made up of a code used in encoding and a code used in decoding, and is characterized by being provided with a transmitter which uses one of the codes to encode and transmit communication data, and a receiver which decodes the received communication data using the code paired with the code used by the transmitter to encode said communication data, wherein the code for encoding and the code for decoding are a non-zero value when the paired codes are multiplied by any phase and added across a fixed period, and are approximately 0 when codes of different pairs are multiplied by any phase and added over a fixed period.

Description

Wireless communication system

The present invention relates to a wireless communication system.

As background art of this technical field, there is JP-A-2001-345783 (Patent Document 1). This publication “has a configuration characterized in that spectrum transmission is performed by spread spectrum using a spreading code in which the side lobe of the autocorrelation function is 0 and the cross-correlation function is 0 at a predetermined phase” It is described.

Japanese Patent Laid-Open No. 2001-345783

Patent Document 1 describes a multiplex communication system using spreading codes. In this method, it is necessary to synchronize between a code used for encoding and a code used for decoding at the time of decoding. However, there is a problem that the longer the code length, the larger the scale of the synchronization circuit and the time required for synchronization.

Therefore, the present invention provides a wireless communication system that can perform decoding without having to synchronize codes.

In order to solve the above-described problem, the present invention is a wireless communication system that performs communication using a plurality of pairs of codes used for encoding and codes used for decoding, and communication data is transmitted using any code. A transmitter for encoding and transmitting; and a receiver for combining the received communication data with the communication data using a code paired with the code used by the transmitter for encoding. The code to be decoded and the code to be decoded are multiplied by a certain phase and added over a fixed period, and become a non-zero value, and different pairs of codes are multiplied with a random phase and added over a fixed period. Then, it becomes about 0.

The present invention provides a wireless communication system capable of decoding without having to synchronize between a code used for encoding transmission data and a code used for decoding received data.

It is an example of the application of this radio | wireless communications system. It is an example of a structure of a transmitter. It is an example of a structure of a receiver. It is an example of a structure of a complex multiplier. This is an example of decoding data encoded with a code (1 + i + 1 + i 1 + i 1 + i). The circuit encoded with the code (1 + i 1 + i 1 + i 1 + i) receives the data encoded with the code (1 + i 1-i -1-i -1 + i). It is an example when it is input. This is an example of decoding data encoded with a code (1 + i 1-i -1-i -1 + i). The circuit that decodes the data encoded with the code (1 + i 1-i -1-i -1 + i) was encoded with the code (1 + i -1 + i -1-i 1-i) It is an example when data is input This is an example of application of the present radio system to a radio using the MIMO scheme. It is a structural example of the transmitter of the radio | wireless communications system using a polarization angle diversity system. It is a structural example of the receiver of the radio | wireless communications system using a polarization angle diversity system. It is an example of a structure of the radio | wireless communication system using a polarization angle diversity system. It is an example of the structure of the transmitter using FPGA. It is an example of the structure of the receiver using FPGA.

Hereinafter, examples will be described with reference to the drawings.

In this embodiment, a wireless communication system in which a plurality of wireless terminals communicate with one wireless base station is shown.

Fig. 1 shows an example of the configuration of this wireless communication system. 100.a, 100.b, and 100.c are representative of wireless terminals. These wireless terminals perform wireless communication with the base station 200 using radio waves of the same frequency.

Different data A, B, and C are transmitted from the wireless terminals 100.a, 100.b, and 100.c, and the base station 200 receives the combined signal as a received wave. In order to identify transmission data from each wireless terminal 100.a, a100.b, and 100.c, spectrum spreading is performed using a different spreading code for each transmission wave.

The base station 200 can identify a signal from each wireless terminal 100.a, 100.b, こと 100.c by decoding using a code corresponding to each spreading code. Code set [(1 1 1 1), (1 i -1 -i), (1 -i -1 i)] as a code for encoding, and a combination of translation, rotation, and scaling on the complex plane A modified code set is used. In all the embodiments below, a spreading code used for encoding is called an encoding code, and a code used for decoding corresponding to the encoding code is called a decoding code. Fig. 2 shows a configuration example of a transmitter in this wireless system. The transmission data generated by the transmission data generation unit 101 is multiplied by the multiplier 102 and the encoding code generated by the code generation unit 104 in two systems of I phase and Q phase. Since the same transmission data is multiplied by a code in two systems of the I phase and the Q phase, it is possible to multiply a code composed of complex numbers.

As the encoding code, in this embodiment, a code set of code length 4 [(1 + i 1 + i 1 + i 1 + i), (1 + i 1-i -1-i -1 + i), ( 1 + i -1 + i -1-i 1-i)]. This is the original code set [(1 1 1 1), (1 i -1 -i), (1 -i -1 i)] rotated 45 ° on the complex plane and expanded to √2 times. is there.

When this code set is used, the code set [(1 + i 1 + i 1 + i 1 + i), (1 + i -1 + i -1-i 1-i), (1 + i 1-i -1-i -1 + i)]. For example, when a code (1 + i 1-i -1-i -1 + i) is used as the encoding code, the real part of the code is repeated in the order of (1I1 -1 -1) in the I phase. Multiply. Similarly, in the Q phase, the coefficient of the imaginary part of the code is repeatedly multiplied in the order of (1 -1 -1 1). At this time, the code repetition period is shorter than the transmission data period. The encoded transmission data is converted into an analog signal in each of the I-phase and Q-phase by a digital-analog converter (hereinafter referred to as DAC) 103. The carrier wave generated by the oscillator 106 is modulated by being multiplied by the analog-converted signal. At this time, the phase of the Q-phase carrier is delayed by a quarter period with respect to the I-phase carrier by the delay unit 105. The adder 107 adds the I-phase and Q-phase signals. The added signal is band-limited by a band-pass filter 109, amplified by a power amplifier (hereinafter referred to as PA) 110, and transmitted from the transmission antenna 108.

Fig. 3 shows a configuration example of a receiver in this wireless system.

The receiver 200 requires the receiving circuit shown in FIG. 3, one for each code of the code set. A signal transmitted from the transmitter 100 is received by the receiving antenna 201 and amplified by a low noise amplifier (hereinafter referred to as LNA) 202. The amplified received wave is band-limited by a bandpass filter 109. Thereafter, the received wave is multiplied by the carrier 102 regenerated by the carrier regenerator 207 and multiplied by the multiplier 102 in two systems of I phase and Q phase, and demodulated by passing through the low-pass filter 205. At this time, the carrier wave multiplied by the Q phase is delayed by a quarter period with respect to the carrier wave multiplied by the I phase by the delay unit 105. The demodulated signal is digitally converted by an analog-to-digital converter (hereinafter referred to as ADC) 203 for each of the I phase and Q phase. The digitally converted signal is complex multiplied by the decoding code generated by the code generation unit 104 by the complex multiplication circuit 300. The complex-multiplied signal is accumulated by the period adder 204 for the same time as the period of the code, and is processed by the reception data processing unit 206 to become reception data.

Describes the decryption method. In decoding, it is necessary to distinguish between data encoded with a target encoding code and data encoded with other encoding codes. In the following description of the decoding method, the data to be encoded is always 1 for simplicity. The code period is t. In order to decode data encoded with a certain encoding code, the complex decoding circuit 300 performs complex multiplication on the corresponding decoding code, and the period addition circuit 204 performs integration for the same period as the code period.

FIG. 4 shows a configuration example of the complex multiplication circuit 300. For the signal input to the complex multiplication circuit 300, the real part of the decoding code generated by the code real part generation unit 301 is multiplied by the multiplier 102 in the I phase, and the code imaginary part generation unit 302 in the Q phase. The multiplier 102 sequentially multiplies the coefficients of the imaginary part of the generated decoding code. The multiplication results are added separately by the adder 107 for the real part and the imaginary part, and the real part is output as the I phase and the imaginary part is output as the Q phase. First, consider decoding data encoded with a code set code (1 + i 1 + i 1 + i 1 + i). In this case, the complex decoding circuit 300 multiplies the same code (1 + i 1 + i 1 + i 1 + i) as the corresponding decoding code.

FIG. 5 is a diagram showing a case where data encoded with an encoding code (1 + i 1 + i 1 + i 1 + i) targeted by the complex multiplication circuit is received. Since it is assumed that the data to be encoded is always 1 at this time, the encoded data 501 is a repetition of (1 + i 1 + i 1 + i 1 + i). On the other hand, when the decoding code 502 is multiplied, the complex multiplication result 503 is repeated as ( 2i 2i 2i 2i). When this is integrated over time in the cycle t of the code in the cycle adder 204, the result is 8i · t. It is obvious that the addition result is constant regardless of the phase of the encoding code and the decoding code.

On the other hand, for the complex multiplication circuit 300 for decoding data encoded with the code (1 + i 1 + i 1 + i 1 + i), different encoding codes (1 + i, Consider a case where data encoded with 1-i, -1-i, -1 + i) is received.

FIG. 6 is a diagram showing a case where data encoded with different encoding codes (1 + i, 1-i, -1-i, -1 + i) of the same code set is received. The encoded data 601 is a repetition of (1 + i 1-i -1-i -1 + i). When the decoding code 602 is multiplied here, the complex multiplication result 603 is repeated (2i, 2, -2i, -2). When this is integrated in the period addition circuit 204 for the time of the period t of the code, it becomes zero. Also in this case, it is obvious that the addition result is constant regardless of the phase of the encoding code and the decoding code. Similarly, when data encoded by another code (1 + i -1 + i -1-i 1-i) is received, the addition result is 0.

Next, consider decoding data encoded with another code (1 + i 1-i -1-i -1 + i) of the same code set. In order to decode this data, a code (1 + i -1 + i -1-i 1-i) is complex multiplied as a corresponding decoding code.

FIG. 7 is a diagram showing a case where data encoded with an encoding code (1 + i 1-i -1-i -1 + i) as an object is received by this complex multiplication circuit. It is assumed that the decoding code 702 is multiplied by the time Δt (0 ≦ Δt <t / 4) and multiplied by the encoded data 701. Then, the complex multiplication result 703 becomes (2 2i 2 2i 2 2i 2 2i). At this time, the time when 2 is output is Δt, and the time when 2i is output is 4 / t−Δt. From this result, it can be seen that the complex multiplication result 703 takes a non-zero value regardless of Δt. The sum of the absolute value of the real part and the absolute value of the imaginary part takes a constant value 2t regardless of Δt. This is also true when Δt is greater than t / 4. From this, it can be seen that the correlation function of the encoding code and the decoding code is a non-zero value at any phase.

On the other hand, for the complex multiplication circuit 300 for decoding the data encoded with the code (1 + i 1-i -1-i -1 + i), different encoding codes (1+ Consider a case where data encoded by i -1 + i -1-i 1-i) is received.

FIG. 8 is a diagram showing a case where data encoded with different encoding codes (1 + i -1 + i -1-i 1-i) of the same code set is received. Now, it is assumed that the decoding data 802 is multiplied by the time Δt (0 ≦ Δt <t / 4) and multiplied by the encoded data 801. Then, the complex multiplication result 803 is the repetition of (2 2i -2 -2i 2 2i -2 -2i). The time when 2 and -2 are output is Δt, the time when 2i and -2i are output is 4 / t-Δt, and the period addition result is 0 regardless of Δt. Similarly, when data encoded with the code of the code set (1 + i 1 + i 1 + i 1 + i) is received, it becomes 0 regardless of Δt.

Finally, when decoding the data encoded with the code (1 + i -1 + i -1-i 1-i), the code (1 + i 1-i -1-i -1+ i) Complex multiplication. The subsequent results are the same as when decoding data encoded with the code (1 + i 1-i -1-i -1 + i).

In the description of the decoding so far, it has been assumed that the period adder 204 can continuously accumulate, but in reality, it is discretely added at a certain period. However, if the number of times of sampling in each element of the code is the same as the timing, the same result can be obtained even in a discrete case.

As can be seen from these decoding methods, when decoding the data encoded with the target encoding code, the value becomes non-zero regardless of the phase, and the data encoded with the other encoding codes Decodes to 0. Therefore, for example, even when data encoded by the target encoding code and data encoded by other encoding codes arrive at the same time, the multiplication of the decoding code regardless of the phase is sufficient. Only data encoded by the encoding code can be extracted.

So far, the decoding method has been described on the assumption that all the data is 1. Next, a method of transmitting and receiving actual data using this encoding and decoding method will be described. Here, digital binary values are treated as 1 and -1. First, prepare the data you want to send. At this time, the 1-bit time of the data needs to be longer than one cycle of the code. The transmission data generating unit 101 adds identification data (1 デジタル -1 1 -1 1 1) for identifying the binary data to the head of the data string. This identification data is determined in advance and shared by the transceiver. The data to which the identification data is added is multiplied by an encoding code. Taking the case of sign (1 + i 1-i -1-i -1 + i) as an example, while data is 1, (1 + i 1-i -1-i -1 + i),- While it is 1, (-1-i -1 + i 1 + i 1-i) is repeated.

This encoded data is transmitted from the transmitter and received by the receiver. The receiver multiplies the decoding code (1 + i -1 + i -1-i 1-i), and the period adder 204 adds one period of the code for decoding. Assuming that the decoding code is shifted from the coding code by t / 8 with respect to the code period t, the decoded data is 4 + 4i while the transmission data is 1, and -4 while the transmission data is -1. -4i. In this decoded data, the added identification data is (4 + 4i -4-4i 4 + 4i -4-4i 4 + 4i 4 + 4i), and this is detected by the received data processing unit 206. It can be seen that 4 + 4i corresponds to 1, and -4-4i corresponds to -1. As a result, the original transmission data can be correctly restored from the decoded data. The above is the transmission / reception method in this wireless communication system. From the above results, in this wireless communication system, it is possible to decode the spread spectrum transmission data without synchronizing the encoding code and the decoding code.

As described above, in this embodiment, communication is performed using a plurality of pairs of encoding codes and decoding codes. Here, the encoding code and decoding code to be used are codes that have strong autocorrelation and zero cross-correlation. In other words, when the paired encoding code and decoding code are multiplied by an arbitrary phase and cyclic addition is performed, a non-zero value is obtained, and different pairs of encoding code and decoding code are multiplied by any phase and cyclic addition is performed. Then it becomes zero.

As described above, since a desired value can be obtained regardless of the phase to which the sign is multiplied, the synchronization circuit is not necessary, and the apparatus can be reduced in size.

In Example 1, since the code length of the code used was 4, the number of wireless terminals that can communicate simultaneously was 3 or less. In the present embodiment, an example is applicable even when the number of wireless terminals is four or more. When the number of wireless terminals is 4 or more, the code is expanded and the number of codes in the code set is increased. The extension of the code can be realized by repeating the code, expanding the similarity, and a combination thereof.

For example, when a code set of code length 8 is created based on a code set of code length 4 [(1 1 1 1), (1 i -1 -i), (1 -i -1 i)], the code set [( 1 1 1 1 1 1 1 1), (1 1 ii -1 -1 -i -i), (1 1 -i -i -1 -1 ii), (1 i -1 -i 1 i -1- i), (1 -i -1 i 1 -i -1 i)]. The decoding code corresponding to this coding code is [(1 1 1 1 1 1 1 1), (1 1 -i -i -1 -1 ii), (1 1 ii -1 -1 -i -i ), (1 -i -1 i 1 -i -1 i), (1 i -1 -i 1 i -1 -i)]. By using the same processing as in the first embodiment using this, it is possible to construct a wireless communication system with up to five wireless terminals at the same time. By extending the code from the above results, a wireless communication system with an increased number of wireless terminals can be constructed.

In this embodiment, an embodiment in a wireless communication system using a MIMO (Multiple-Input Multiple-Output) scheme is shown. FIG. 9 shows a configuration example of this embodiment. Three transmitters 100 according to the first embodiment are mounted in the transmitter 901, and the communication capacity is increased by transmitting different data simultaneously from the respective antennas 903.a, 903.b, and 903.c. . In this case, the code set [(1 + i 1 + i 1 + i 1 + i), (1 + i 1-i -1-i -1 + i), (1 + i -1 + i -1-i 1-i)]. Three receivers 200 according to the second embodiment are mounted in the receiver 902, and each of the receiving antennas 904.a, 904.b, and 904.c has three transmitting antennas 903.a and 903.b. The transmission wave from 903.c is synthesized and received. At this time, the phases of the encoding codes of the three transmission waves synthesized are not aligned.

Similar to the first embodiment, a decoding code set [(1 + i 1 + i 1 + i 1 + i), (1 + i -1 + i -1-i 1-i), ( 1 + i 1-i -1-i -1 + i)], the data other than the data encoded with the target encoding code is 0 regardless of the code phase. Therefore, only data encoded by the target encoding code can be selectively extracted. By selectively extracting transmission data from data received by the three antennas 904.a, 904.b, and 904.c of the MIMO receiver, the communication capacity can be increased.

As described above, by applying the present invention to the wireless communication system using the MIMO scheme, the communication capacity can be increased in addition to the effects of the first embodiment. Further, by expanding the code as in the second embodiment, the number of antennas that can be simultaneously transmitted and received can be increased, so that the communication capacity can be further increased.

In the present embodiment, an embodiment in a wireless communication system to which a polarization angle diversity system that switches a polarization angle every time is applied will be described.

Fig. 10 shows a configuration example of the transmitter of this system. The encoding code can be switched by a code switch 1001. Further, the polarization angle of the transmission wave can be changed by adjusting the power input to the vertically polarized antenna 1003 and the horizontally polarized antenna 1004 by the antenna switch 1002.

Fig. 11 shows a configuration example of the receiver of this wireless system. One set of each of the code generation unit 104, the complex multiplication circuit 300, and the period adder 204 is required for the number of polarization angles to be used.

In wireless communication using the polarization angle diversity method, the transmitted wave may pass through different propagation paths for each polarization angle. As shown in FIG. 12, since the time required for propagation differs for each path that passes through, the transmission waves having a plurality of polarization angles transmitted from the transmitter 1000 reach the receiver 1100 in a combined state. In the transmitter 1000, the code pairs of the present invention [(1 + i 1 + i 1 + i 1 + i), (1 + i 1-i -1-i -1 + i), (1 + i -1 + i -1-i 1-i)] is used to encode the data.

For example, a code (1 + i 1 + i 1 + i 1 + i) is transmitted for a transmission wave transmitted at a polarization angle of 0 °, and a code (1 + i 1) is transmitted for a transmission wave transmitted at a polarization angle of 45 °. -i -1-i -1 + i), and a transmission wave transmitted at a polarization angle of 90 ° is encoded using a code (1 + i -1 + i -1-i 1-i). The code switch 1001 that switches the encoding code and the antenna switch 1002 that changes the polarization angle are time-synchronized, and the encoding code and the polarization angle can be switched simultaneously. At the receiver, the decoding code sets [(1 + i 1 + i 1 + i 1 + i), (1 + i -1 + i -1-i 1-i), (1 + i 1-i- 1-i -1 + i)] is used in the same manner as in the first embodiment, so that data for each polarization angle can be selectively received from the synthesized received wave. Further, by extending the code as in the second embodiment, it is possible to increase the polarization angle to be used.

As described above, by applying the present invention to a radio apparatus using the polarization angle diversity system, it is possible to receive data without having to synchronize codes every time the polarization angle is changed.

In this example, an embodiment of a software defined radio using an FPGA is shown. FIG. 11 shows a configuration example of a transmitter, and FIG. 12 shows a configuration example of a receiver.

First, in the FPGA 1301 of the transmitter, the transmission data generation unit 101 adds a header (1 -1 1 -1 1 1) to the transmission data. Code set [(1 + i 1 + i 1 + i 1 + i), (1 + i 1-i -1-i -1 + i), (1 + i -1 + i -1-i 1-i )] Is used to encode the data. The multiplier 102 multiplies the real part of the code in the I phase and the imaginary part of the code in the Q phase. Each of these is multiplied by the carrier wave generated by the carrier wave generating unit 401 in the FPGA. At this time, the phase of the carrier wave multiplied by the Q phase is shifted by a quarter period by the delay unit 105. The encoded data is added by the adder 107 and converted into an analog signal by the DAC 103 outside the FPGA 1301. The analog-converted data is amplified by the PA 110, band-limited by the band-pass filter 109, and then transmitted from the transmission antenna 108.

The transmitted data is received by the antenna 201 of the receiver and amplified by the LNA 202. The amplified signal passes through the band-pass filter 109, is digitally converted by the ADC 203, and is input to the FPGA 1301. The input signals are I-phase and Q-phase, respectively, and the multiplier 102 multiplies the sine wave 4 generated by the sine wave generation unit 402 and having the same frequency as the carrier wave. The sine wave multiplied by the Q phase is delayed by a quarter period with respect to the I phase by the delay unit 104. At this time, since the phase of the sine wave to be multiplied is not synchronized with the phase of the carrier wave of the received signal, the phase may be shifted. Phase shift is (1) -π / 4 or more and less than π / 4 (2) π / 4 or more and less than 3π / 4 (3) 3π / 4 or more and less than 5π / 4 (4) 5π / 4 or more and 7π / The case is divided into one of less than 4. Data is received correctly in the case of (1), but is received i times in the case of (2), -1 times in the case of (3), and -i times in the case of (4). In either case, when the phase is shifted by π / 4, the power of the data is reduced by a maximum of cos (π / 4) times. However, this is not a problem if it is sufficiently amplified by the amplifier. The signal multiplied by the sine wave passes through the low-pass filter 205 and is then multiplied by the decoding code in the complex multiplier 300. Thereafter, one period of code is added by the period adder 204, and the reception data processing unit 206 becomes reception data. The received data is multiplied by a constant due to the deviation of the sine wave. However, as described in the first embodiment, since data other than the data encoded with the desired encoding code is 0, the added identification data is By confirming, it is possible to obtain desired data. For example, in the case of (2), the identification data is (i -i i -i i i).

As described above, by using the present invention, it is possible to receive data without synchronizing the phase of the carrier wave in the software defined radio using the FPGA. In this embodiment, Embodiment 2-4 can be implemented with the same configuration.

In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment. Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, and files for realizing each function can be stored in a recording device such as a memory, a hard disk, or an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

100, 100.a 100.b 100.c Transmitter 101 Transmission data generation unit 102 Multiplier 103 Digital analog converter 104 Code generation unit 105 Delay unit 106 Oscillator 107 Adder 108 Transmission antenna 109 Bandpass filter 110 Power amplifier 200 Reception 201 Receiving antenna 202 Low noise amplifier 203 Analog to digital converter 204 Periodic adder 205 Low pass filter 206 Received data processing unit 300 Complex multiplier circuit 301 Code real part generator 302 Code imaginary part generator 401 Carrier wave generator 402 Sine wave generator 501 Encoded data 502 Decoding code 503 Complex multiplication result 601 Encoded data 602 Decoding code 603 Complex multiplication result 701 Encoded data 702 Decoding code 703 Complex multiplication result 801 Encoded data 802 Code 803 Complex multiplication result 901 MIMO transmitter 902 MIMO receiver 903.a 903.b 903.c MIMO transmit antenna 904.a 904.b 904.c MIMO receive antenna 1000 Polarization angle diversity transmitter 1001 Code switcher 1002 Antenna switch 1003 Vertical polarization antenna 1004 Horizontal polarization antenna 1100 Polarization angle diversity receiver 1200 Shield 1301 FPGA

Claims

A wireless communication system that performs communication using a plurality of pairs of codes used for encoding and codes used for decoding,
A transmitter that encodes and transmits communication data using any code;
A receiver that combines the communication data with the received communication data using a code that is paired with the code used by the transmitter for encoding;
The code to be encoded and the code to be decoded have a non-zero value when the codes in pairs are multiplied by an arbitrary phase and added over a certain period, and the codes of different pairs are multiplied by an arbitrary phase and are constant. A wireless communication system characterized in that the sum is approximately 0 when added over a period.
The wireless communication system according to claim 1, wherein
The receiver includes a multiplier that performs complex multiplication of a demodulated signal obtained by demodulating a received radio signal and a code, and a periodic adder that adds a real part and an imaginary part of the output of the multiplier over a certain period, respectively. A wireless communication system.
The wireless communication system according to claim 1, wherein
The code used for the encoding is a code set [(1 1 1 1), (1 i -1 -i), (1 -i -1 i)] or complex when i is an imaginary unit. A wireless communication system using a code set deformed by a combination of translation, rotation, and enlargement / reduction on a plane.
The wireless communication system according to claim 1, wherein
The codes used for the encoding are code sets [(1 1 1 1 1 1 1 1), (1 1 ii -1 -1 -i -i), (1 1 -i- i -1 -1 ii), (1 i -1 -i 1 i -1 -i), (1 -i -1 i 1 -i -1 i)].
The wireless communication system according to claim 1, wherein
The code used for the encoding is a code set [(1 1 1 1), (1 i -1 -i), (1 -i -1 i)] or complex when i is an imaginary unit. A wireless communication system characterized in that a code set deformed by a combination of translation, rotation, and enlargement / reduction on a plane is repeated, and a code set expanded by similarity enlargement and the combination thereof is used.
The wireless communication system according to claim 1, wherein
The wireless communication system, wherein the transmitter adds identification data shared with the receiver in advance to the communication data for transmission.
The wireless communication system according to claim 1, wherein
The transmitter transmits a plurality of carrier waves having different polarization angles, and wirelessly encodes the communication data using a code determined for each polarization angle of the carrier wave carrying the communication data. A wireless communication system characterized by transmitting.