Cdma radio multiplex sender and cdma radio multiplex transmitter

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to a CDMA radio multiplex transmission device and a CDMA radio multiplex transmission device used for digital cellular communication and the like.

【0002】

[Conventional technology]

The multiple access method is a line connection method when a plurality of stations communicate at the same time in the same band. CDMA (Code Division Multiple Access) is a code division multiple access, a technology that performs multiple access by spread spectrum communication, which spreads the spectrum of an information signal over a band sufficiently wider than the original information bandwidth and transmits it. Is. Sometimes referred to as Spectral Access Method (SSMA). The direct diffusion method is a method in which the diffusion sequence code is directly multiplied by the information signal in diffusion. In direct diffusion CDMA, since multiple communications share the same frequency, there is a problem (perspective problem) in which the strength of the interference wave (communication wave of another station) at the receiving end and the desired wave are the same, and this is overcome. Is a prerequisite for the realization of a CDMA transmission system. The perspective problem becomes severe in base station reception, which simultaneously receives radio waves from multiple stations at different positions. Therefore, it is essential for mobile stations to control transmission power according to the state of each transmission line. On the other hand, when the reception power of a specific received signal is stronger than that of other signals, the reliability of the signal is high. TDD (Time Division) Duplex) is a transmission / reception same-band system, also called a ping-pong system, and is a system in which the same radio frequency is divided into transmission / reception time divisions for communication.

【0003】

In addition, among the detection methods in digital communication, the synchronous detection method has superior static characteristics compared to the delayed detection method, and the Eb / I0 required to obtain a certain average bit error rate (BER) is the lowest. is there. An interpolated synchronous detection method has been proposed as a method for compensating for distortion of a transmission signal due to fading (Seiichi Sankei, "16QAM Fading Distortion Compensation Method for Land Mobile Communication" Shingakuron B-II Vol.J72 -B-II No.1 pp.7-15,1989). In this method, a pilot symbol is periodically inserted into the information symbol to be transmitted, and the transfer function of the channel, that is, the state of the line is estimated and the detection is performed. In addition, a method that applies the above method to direct sequence spread spectrum has been proposed (Higashi, Oguchi, Ohno, "Characteristics of interpolated synchronous detection RAKE in DS / CDMA". RCS94-98,1994). On the other hand, there is a pilot channel as a method that enables synchronous detection in direct spread CDMA. This is a method in which one channel (diffusion code) is used as a detection reference signal and is always transmitted independently of the channel for transmitting information data. An example of the channel format is shown in FIG. Phase estimation is performed from the pilot channel by back diffusion, and synchronous detection of information data is performed. In this case, in order to improve the reliability of the pilot signal, it may be transmitted with stronger power than the channel for transmitting other information data or the like.

【0004】

In direct diffusion CDMA, there is multi-code transmission as a method of transmitting information exceeding the information transmission speed per channel (1 diffusion code). This is a method in which a plurality of channels, that is, a plurality of spreading codes are assigned to one user, and the transmitting side divides and spreads information data into a plurality of channels, and multiplexes and transmits the information data. When performing synchronous detection in this multi-code transmission, it is conceivable to use the above pilot symbol or pilot channel.

【0005】

FIG. 12 shows a conventional example of a multiplex channel format when multi-code transmission is performed using a pilot symbol. Information data is transmitted using N channels (diffusion code 0 to N-1). A pilot symbol (PL signal) 1201 is interpolated in each channel every period T. Therefore, it can be seen that the receiving side can perform synchronous detection using the pilot symbol for each channel.

【0006】

[Problems to be Solved by the Invention]

However, in the above-mentioned conventional multi-code transmission, the transmission power of the pilot symbol is the same as that of the information data, and there is also the influence of interference between the pilot symbols, especially the cross-correlation of the diffusion code, so that highly reliable synchronous detection is difficult. there were.

【0007】

On the other hand, FIG. 13 shows an example of signal format when multi-code transmission is performed using the pilot channel. On the receiving side, phase estimation is performed from the pilot channel by reverse diffusion, and synchronous detection of information data is performed. However, in this case, since the pilot signal is transmitted in the information data transmission section, the information data signal interferes with the pilot signal. In addition, the pilot signal also interferes with the information data signal. In particular, in order to increase the reliability of the pilot signal, a large amount of interference will be given when the pilot signal is transmitted with a power stronger than that of the information data transmission channel.

【0008】

The present invention solves such a conventional problem, and provides an excellent CDMA radio multiplex transmission device and a transmission device capable of improving the reliability of the pilot symbol and improving the performance of synchronous detection. The purpose is.

【0009】

[Means for solving problems]

In order to achieve the above object, the present invention provides a means for periodically interpolating and transmitting a pilot symbol in only one channel (one spreading code) of the multiplexing channel on the transmitting side, and the other in this pilot symbol transmission section. No data is transmitted on the channel, and the receiving side is equipped with a means for estimating the line state (transfer function) from the received pilot symbol, and synchronous detection of each multiplexed channel is performed based on that information. It is a thing.

【0010】

[Action]

Therefore, according to the present invention, the transmitting side can reduce the interference between the pilot channels by interposing the pilot symbol in only one channel and transmitting the symbol. Further, on the receiving side, the interference with the pilot symbol is reduced, so that the reliability is improved, and based on this, synchronous detection of all the multiplexed channels becomes possible, and the detection performance can be improved.

【0011】

[Example]

(Example 1) FIG. 1 shows a configuration of a CDMA radio multiplex transmission device according to a first embodiment of the present invention. In FIG. 1, 101 is transmission data, 102 is a separation circuit, 103 is a diffusion circuit, 104 is a switch, 105 is a PL signal, 106 is a multiplex circuit, 107 is a wireless transmitter, and 108 is an antenna.

【0012】

The transmission data 101 is separated into N + 1 channels by the separation circuit 102. The signal of each channel is spread by the spreading circuit 103 having a different spreading code and multiplexed by the multiplexing circuit 106. The pilot symbol (PL signal) 105 is inserted by the switch 104 into the channel having the spread code 0 every period T. In the pilot symbol insertion section, there is no transmission signal of other channels, so the transmission signal in this section is only the pilot symbol. The multiplexed signal is modulated by the radio transmission unit 107, up-converted to the transmission frequency, and then transmitted from the antenna 108.

【0013】

FIG. 2 shows an example of a channel format in the multi-code transmission of this embodiment. In the period T, the PL signal transmission section 201 and the information data transmission section 202 are composed, and the PL signal 203 is inserted into the PL signal transmission section 201. The N + 1 channel signals are multiplexed, and only the PL signal 203 having spread code 0 is transmitted every period T. In this method, the spreading code used for the PL signal may be other than the code used for spreading the transmitted data, and it is clear that the PL signal 301 may be given an independent spreading code as shown in the example of FIG. is there.

【0014】

According to the above embodiment, the transmitting side can reduce the interference between the pilot channels by interposing the pilot symbol in only one channel and transmitting the symbol. Further, on the receiving side, the interference with the pilot symbol is reduced, so that the reliability is improved, and based on this, synchronous detection of all the multiplexed channels becomes possible, and the detection performance can be improved.

【0015】

(Example 2) The configuration of the CDMA radio multiplex transmission device in this embodiment is the same as that in the first embodiment. Figure 4 shows a configuration example of the CDMA wireless multiplex receiver. In FIG. 4, 401 is an antenna, 402 is a wireless receiver, 403 is a reverse spread circuit, 404 is a switch, 405 is a PL signal, 406 is a line state estimation circuit, 407 is a synchronous detection circuit, 408 is a binary judgment circuit, and 409. Is the composite circuit and 410 is the received data.

【0016】

The signal received by the antenna 401 is down-converted by the radio receiver 402, demodulated, and then despread by the despread circuit 403 using each diffusion code. The pilot symbol (PL signal) 405 is extracted from the signal despread by the spreading code 0 via the switch 404, and the transfer function of the line is estimated in the line state estimation circuit 406 based on the information. Then, each channel is detected by the synchronous detection circuit 407 by using the phase of each symbol of the information data transmission section estimated by the line state estimation circuit 406. Further, it is binarized by the binarization circuit 408, combined into one data series by the synthesis circuit 404, and output as received data 410.

【0017】

According to the above embodiment, in multi-code transmission, by receiving the pilot symbol transmitted with only one spreading code, interference between the pilot symbols is eliminated, and the line state is estimated from the highly reliable pilot symbol. , Synchronous detection of all multiplexed channels can be performed.

【0018】

(Example 3) FIG. 5 shows the configuration of the CDMA radio multiplex transmission device in this embodiment. The configuration is such that the transmission power control 509 is added to the wireless transmission unit 107 of FIG. 1 shown in the first embodiment. Therefore, the configuration is the same as that in FIG. 1 except for the above 509.

【0019】

Similar to Example 1, the transmit data 501 is separated into N + 1 channels by the separation circuit 502. The signal of each separated channel is spread by the spreading circuit 503 having a different spreading code, and is multiplexed by the multiplexing circuit 506. The pilot symbol (PL signal) 505 is inserted into the channel having the spread code 0 every period T by the switch 504. There is no transmission signal of other channels in the pilot symbol insertion section, so the transmission signal in this section is only the pilot symbol. The multiplexed signal is modulated by the radio transmission unit 507, up-converted to the transmission frequency, and then transmitted from the antenna 508. At this time, the wireless transmission unit 507 periodically performs transmission power control by the transmission power control signal 509, so that the transmission power per channel of the pilot symbol transmission section is made stronger than that of the other sections for transmission. The operation on the receiving side is the same as that in the second embodiment.

【0020】

According to the above embodiment, since the interference with the pilot symbol is relatively small, the reliability of the pilot symbol can be made higher, and the synchronous detection performance can be improved. As a method of transmitting by making the transmission power of the pilot symbol transmission section stronger than that of other sections, in addition to the method of controlling the transmission power in time, the pilot symbol signal 505 before spreading with the spreading code 0 It is also conceivable to realize this by making the transmission data signal larger than the transmission data signal. For example, if the transmission data signal is a binary signal of ± 1, if the pilot symbol signal 505 is diffused and transmitted as a signal of ± m and a signal of m times the magnitude, the pilot symbol will be transmitted per channel of transmission data. Transmission power m²It means that it was sent with twice the power (assuming = M).

【0021】

(Example 4) The configuration of the CDMA radio multiplex transmission device in this embodiment is the same as that in the first embodiment. In FIG. 1, when the transmission data 101 is separated by the separation circuit 102, the control data and the information data (voice data, etc.) are distinguished and sent to the diffusion circuit 103 as different channels. When the transmission data 101 is separated and input into two signal lines of control data and information data from the beginning, it is not necessary to re-separate by the separation circuit 102. Subsequent operations are the same as in Example 1.

【0022】

Figure 6 shows an example of the channel format in the above multi-code transmission. This is an example in which N + 1 channel signals are multiplexed and only the PL signal 601 with diffusion code 0 is transmitted with a power of M times (1 M N + 1) of the data transmission section for each period T. In this example, the multiplexed channels include a communication D channel 602 for transmitting control data and a communication B channel 603 for transmitting information data, and the transmission of the PL signal 601 is performed using the spread code 0 of the D channel. It is done.

【0023】

When the control data is distributed and transmitted to each channel, the transmission speed of the control data changes depending on the number of multiple channels. This is an inefficient transmission method in a system in which the amount of control data does not depend on the transmission speed of information data. On the other hand, in the method of transmitting control data and information data on different channels as in the above method, efficient control data transmission is possible without being affected by the number of multiplex information data. Therefore, efficient multi-code transmission can be realized by applying it to a system that accommodates various information data having different transmission speeds.

【0024】

(Example 5) The configuration of the CDMA radio multiplex transmission device in this embodiment is the same as that in the first embodiment. Figure 7 shows the configuration of the CDMA radio multiplex receiver. The configuration is such that the RAKE synthesis circuit 710 is added to the configuration of FIG. 4 shown in the second embodiment. Therefore, the configuration is the same as that in FIG. 4 except for the above 710.

【0025】

The signal received by the antenna 701 is down-converted by the radio receiver 702, demodulated, and then despread by the despreading circuit 703 using each spreading code. The pilot symbol (PL signal) 705 is extracted from the signal despread by the spreading code 0 via the switch 704, and the transfer function of the line is estimated in the line state estimation circuit 706 based on the information. At this time, the line state estimation circuit 706 not only estimates the phase of each symbol for synchronous detection, but also sets and updates the delay line weighting coefficient using the pilot symbol as a training signal required for RAKE, which is a path diversity. Do. Then, each channel is detected by the synchronous detection circuit 707 and path-diversified by the RAKE synthesis circuit 710 using the phase and the like of each symbol in the estimated information data transmission section. Further, it is binarized by the binarization circuit 708, combined into one data series by the synthesis circuit 709, and output as received data 711.

【0026】

According to the above embodiment, in multi-code transmission, the line state (transfer function) is estimated by receiving the pilot symbol transmitted with only one diffusion code, and synchronous detection and RAKE synthesis of all the multiplexed channels are performed. Can be done.

【0027】

(Example 6) The configuration of the CDMA radio multiplex transmission device in this embodiment is the same as that in the first embodiment. Figure 8 shows the configuration of the CDMA radio multiplex receiver. The configuration is such that the transmission power control calculation unit 810 is added to the configuration of FIG. 4 shown in the second embodiment. Therefore, the configuration is the same as that in FIG. 4 except for the above 810.

【0028】

The signal received by the antenna 801 is down-converted by the radio receiver 802, demodulated, and then despread by the despread circuit 803 using each diffusion code. The pilot symbol (PL signal) 805 is extracted from the signal despread by the spreading code 0 via the switch 804, and the transfer function of the line is estimated in the line state estimation circuit 806 based on the information. At this time, in the line state estimation circuit 806, the transmission power is calculated by the transmission power control calculation unit 810 by obtaining the received power and SINR (Signal to Interference-plus-Noise Ratio), and is output to the transmission unit. On the other hand, the despread signal of each channel is detected by the synchronous detection circuit 807 using the phase of each symbol estimated by the line state estimation circuit 806. Further, it is binarized by the binarization circuit 808, combined into one data series by the synthesis circuit 809, and output as received data 811.

【0029】

According to the above embodiment, in multi-code transmission, the performance of line state (transfer function) estimation is improved by receiving the pilot symbol transmitted with only one diffusion code, and synchronous detection of all the multiplexed channels is performed. At the same time, high-performance transmission power control can be performed.

【0030】

(Example 7) FIG. 9 shows the configuration of the CDMA radio multiplex transmission device in this embodiment. A ramp-up (RU) signal 910 and a ramp-down (RD) signal 911 are added to the configuration of FIG. 5 shown in the third embodiment. Therefore, the configuration is the same as that of FIG. 5 except for the above two signals. The lamp signal has the purpose of preventing the generation of spurious out of the transmission band in wireless transmission due to the steep rising and falling edges of the signal in burst transmission.

【0031】

Similar to Example 3, the transmission data 901 is separated into N + 1 channels by the separation circuit 902. The signal of each separated channel is spread by the spreading circuit 903 having a different spreading code and multiplexed by the multiplexing circuit 906. The pilot symbol (PL signal) 905 is inserted into the channel having the spread code 0 every period T by the switch 904. For burst signals, the period T does not have to be constant at all times. The ramp-up (RU) 910 is inserted at the beginning of the transmission section and the ramp-down (RD) signal 911 is inserted at the end of the transmission section. The switching of the signal is performed by the switch 904. In the pilot symbol and lamp signal transmission sections, there are no transmission signals of other channels, so that the transmission signals in these sections are only the channels having the diffusion code 0. The multiplexed signal is modulated by the radio transmission unit 907, up-converted to the transmission frequency, and then transmitted from the antenna 908. At this time, by periodically performing transmission power control by the transmission power control signal 909 in the wireless transmission unit 907, the transmission power in the pilot symbol transmission section is made stronger than the transmission power per channel in the other sections for transmission. It is also possible to do it. The operation on the receiving side is the same as that in the second embodiment.

【0032】

An example of the channel format in the above multi-code transmission is shown in FIG. This is an example of multi-code transmission in CDMA / TDD. In FIG. 10, 1001 is a PL signal, 1002 is a ramp-up signal, 1003 is a ramp-down signal, 1004 is a guard time, 1005 is a communication D channel, 1006 is a communication B channel, 1007 is a transmission section, and 1008 is a reception section. is there.

【0033】

Since TDD is a method in which the same radio frequency is divided into transmission / reception time divisions for communication, the transmission section 1007 and the reception section 1008 are also time-divisioned in FIG. The guard time (GT) 1004 is a section for avoiding collision of transmitted / received signals. In this embodiment, the PL signal 1001 is inserted at the start and end of transmission of information data. When the transmission section is longer than the PL signal interpolation cycle T, a plurality of PL signals are inserted in the information data.

【0034】

In FIG. 10, N + 1 channels are multiplexed, and the PL signal 1001 is transmitted at M times (1 M N + 1) the transmission power per channel in the data transmission section. In this embodiment, the multiplexed channels include a communication D channel 1005 for transmitting control data and a communication B channel 1006 for transmitting information data, and the transmission of the PL signal 1001 using the spread code 0 of the D channel. Is performed. Similarly, the ramp-up (RU) 1002 is inserted into the communication D channel and transmitted at the start of the transmission section and the ramp-down (RD) signal 1003 at the end of the transmission section.

【0035】

According to the above embodiment, in the multi-code transmission of burst transmission, not only the pilot symbol but also the lamp signal is transmitted by only one channel, so that the transmission device can be simplified and the delay wave exceeds one symbol. In such a propagation environment, by reducing the number of spread codes to be multiplexed in the ramp section, the influence of interference (cross-correlation, etc.) on adjacent symbols (pilot symbols in the above example) by the delay wave of the ramp signal is affected. It can also be reduced.

【0036】

[Effect of the invention]

As is clear from the above embodiment, in multi-code transmission, the transmitting side inserts a pilot symbol into only one channel for transmission, thereby eliminating interference between the pilot symbols of each channel and a synchronous system. In the system, by reducing the interference (interference between other stations) given to the pilot symbols of other stations at the same time, the performance of estimating the line state (transfer function) by the pilot symbols is improved, and the synchronous detection performance of all the multiplexed channels is improved. Has the effect of improving. It also has the effect of improving the performance of RAKE synthesis and transmission power control by improving the performance of line state (transfer function) estimation using pilot symbols.

[Simple explanation of drawings]

[Figure 1]

Block diagram showing the configuration of the CDMA radio multiplex transmission device according to the first embodiment of the present invention. [Figure 2]

Schematic diagram showing an example of the channel format in Example 1 of the present invention [Fig. 3]

Schematic diagram showing an example of the channel format in Example 1 of the present invention [Fig. 4]

A block diagram showing a configuration of a CDMA wireless multiple access device according to a second embodiment of the present invention. [Fig. 5]

Block diagram showing the configuration of the CDMA radio multiplex transmission device according to the third embodiment of the present invention. [Fig. 6]

Schematic diagram showing an example of the channel format in Example 4 of the present invention [Fig. 7]

A block diagram showing a configuration of a CDMA wireless multiple access device according to a fifth embodiment of the present invention. [Fig. 8]

A block diagram showing a configuration of a CDMA wireless multiple access device according to a sixth embodiment of the present invention. [Fig. 9]

A block diagram showing a configuration of a CDMA radio multiplex transmission device according to a seventh embodiment of the present invention. [Fig. 10]

Schematic diagram showing an example of the channel format in Example 7 of the present invention [Fig. 11]

Schematic diagram showing an example of transmission by pilot channel [Fig. 12]

Schematic diagram showing an example of a conventional channel format [Fig. 13]

Schematic diagram showing an example of multi-code transmission by pilot channel [Explanation of symbols]

101 Transmission data 102 Separation circuit 103 Diffusion circuit 104 switch 105 PL signal (pilot symbol) 106 Multiple circuits 107 Wireless transmitter 108 antenna 401 antenna 402 Wireless receiver 403 Reverse diffusion circuit 404 switch 405 PL signal 406 Line state estimation circuit 407 Synchronous detection circuit 408 Binary value judgment circuit 409 Synthesis circuit 410 Received data 501 transmitted data 502 Separation circuit 503 Diffusion circuit 504 switch 505 PL signal (pilot symbol) 506 Multiple circuits 507 Wireless transmitter 508 antenna 509 Transmission power control signal 701 antenna 702 Wireless receiver 703 Reverse diffusion circuit 704 switch 705 PL signal 706 Line state estimation circuit 707 Synchronous detection circuit 708 Binary value judgment circuit 709 synthesis circuit 710 RAKE synthesis circuit 711 Received data 801 antenna 802 wireless receiver 803 Reverse diffusion circuit 804 switch 805 PL signal 806 Line state estimation circuit 807 Synchronous detection circuit 808 Binary value judgment circuit 809 synthesis circuit 810 Transmission power control calculation unit 811 Received data 901 Transmission data 902 Separation circuit 903 Diffusion circuit 904 switch 905 PL signal (pilot symbol) 906 Multiple circuit 907 Wireless transmitter 908 antenna 909 Transmit power control signal 910 Lamp-up signal 911 ramp down signal