JP2001320346A - Transmitter, receiver and base station using orthogonal frequency division multiplexing modulation and spread spectrum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitting apparatus, a receiving apparatus, and a base station equipped with them, which extend a transmission distance by spreading and transmitting and receiving orthogonal frequency division multiplex modulation signals. A transmitting apparatus having a means for spreading an orthogonal frequency division multiplex modulation signal, a receiving apparatus having a means for despreading a spread orthogonal frequency division multiplex modulation signal, and a base station equipped with the transmitting apparatus and the receiving apparatus It is. By spreading and transmitting / receiving the orthogonal frequency division multiplex modulation signal, the transmission distance between the transmitting device and the receiving device can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitting apparatus, a receiving apparatus, and a base station on which these apparatuses perform wireless communication using orthogonal frequency division multiplexing demodulation and despreading in combination.

[0002]

2. Description of the Related Art With an increase in the signal transmission speed of a wireless communication system, delay-resistant interference in a multipath transmission line has become an important issue. As a method of solving this delay-resistant interference, OFDM (Or
thogonal Frequency Division Multiplexing). OFDM is a method of independently modulating and multiplexing a plurality of carriers (subcarriers) orthogonal to each other, and has excellent delay interference resistance characteristics in a multipath propagation path. In addition, normal FDM (Frequency Division
It is possible to pack much more carriers than in the case of Multiplexing, and has an advantageous effect that the frequency efficiency is very high. OFDM is adopted as a transmission system for digital broadcasting in Europe, the United States, and Japan. In addition to broadcasting, HIPER- is a next-generation mobile communication system.
Adoption has also been determined in wireless system standards such as LAN / 2 (Europe), IEEE 802.11a (US), and MMAC (Japan).

In the next-generation wireless communication system, a high signal transmission speed of several Mbps to several tens Mbps is assumed, and the occupied bandwidth per channel is set wide. For this reason, it is necessary to further improve the frequency use efficiency as compared with the related art. Further, since available frequency resources are limited, it is a technical problem how to efficiently perform frequency allocation and cell allocation in the cellular system.

Further, in the next generation wireless communication system,
In order to accommodate multimedia information with different required QoS (Quality of Service, service quality of communication), support of different signal transmission rates is assumed.
Support for different signal transmission rates is achieved by changing the modulation scheme and coding rate. Hereinafter, a system that can support different signal transmission rates is referred to as a “multi-rate compatible system”. Table 1 shows an example of the relationship among the signal transmission speed, the coding rate, the modulation scheme, and the reception sensitivity in a multi-rate compatible system.

[0005]

[Table 1] Table 1: Relationship between signal transmission speed, coding rate, modulation method and reception sensitivity Mode Transmission rate modulation Coding rate Receive sensitivity M1 6Mbps BPSK 1/2 -82dBm M2 9Mbps BPSK 3/4 -81dBm M3 12Mbps QPSK 1/2 -79dBm M4 18Mbps QPSK 3/4 -77dBm M5 27Mbps 16QAM 9/16 -74dBm M6 36Mbps 16QAM 3/4 -70dBm M7 54Mbps 64QAM 3/4 -65dBm In the example shown in this table, seven modes M1 to M7 are set. As a matter of course, in order to perform communication at a high signal speed, a good radio propagation environment is required. As shown in the above table, in order to receive a higher signal transmission rate (from mode M1 to mode M7)
F), it is necessary to secure a higher received electric field strength. Conversely, if the signal transmission speed is reduced (from mode M7 to mode M1), the required received electric field strength is reduced. That is, in a multi-rate compatible system, the size (coverage) of a range (cell) within which a radio wave from one base station can reach can be changed by changing the signal transmission speed. More specifically, it is possible to expand the cell coverage by reducing the signal transmission speed.
Hereinafter, a system in which cell coverage changes dynamically,
This is called a “dynamic cell configuration system”.

As conventional examples of the dynamic cell configuration system, B-5-204, "Study on Zone Generation Algorithm in Adaptive Variable Zone Configuration System", Proceedings of the 1998 IEICE General Conference, and the 1998 Communication Society Conference B-5-81 "Study of adaptive variable zone configuration system using directional antenna for base station" in the collection of papers. In these conventional examples, an array antenna is used, and the zone shape of a cell is adaptively changed according to the distribution of mobile stations, thereby shortening the repetition distance of the same frequency and increasing the number of mobile stations per base station. Achieve reduced load.

As another conventional example of the dynamic cell configuration system, there is B-5-89 "Area Configuration Method in Multi-Rate High-Speed Wireless LAN" of the IEICE Transactions on Communication Society 1999. In the conventional example described above, the coverage of the cell is changed by changing the zone shape using the array antenna, whereas in the conventional example disclosed in B-5-89, the transmission rate of the beacon signal is changed. Changes the cell coverage.

[0008] The wider the variable range of cell coverage in a dynamic cell configuration system, the greater the flexibility of the system. Therefore, it is a technical problem how to extend the variable range of cell coverage.

[0009] With the expansion of cell coverage,
Increased interference to neighboring cells must be avoided. That is, the extension of the coverage is closely related to the cell arrangement method in the cellular system. Therefore, there is a problem of how to arrange cells in the dynamic zone configuration.

[0010] In a wireless communication system, it is required to improve the frequency use efficiency. In particular, in a next-generation wireless communication system in which the occupied bandwidth per channel is set widely, available frequency resources are limited, and a system configuration with high frequency use efficiency is required.

As a method for improving the channel use efficiency, there is an intelligent antenna (smart antenna). The intelligent antenna technology is outlined in TB-5-1 “Intelligent Antenna Technology” of the Institute of Electronics, Information and Communication Engineers, “Presentations of the 1999 Communication Society Conference, 1”. The “examination of the zone generation algorithm in the adaptive variable zone configuration system” and the “examination of the adaptive variable zone configuration system using a directional antenna for the base station”, which are the conventional examples of the dynamic cell configuration system described above, are described in It is an application.

As an example of applying the intelligent antenna technology to the OFDM system, SB- of the 1998 IEICE Communication Society Conference Proceedings.
1-3 "unwanted wave suppression characteristics of a multicarrier-CMA adaptive array". In this example, each of the signals received by the plurality of antenna elements is weighted by the weighting device, and then combined by the combiner.
The synthesized signal is converted to a frequency domain signal by FFT. The weight coefficient is set so that the amplitudes of the subcarriers are all equal.
m). It is shown that the control method based on CMA is effective when the reception power of the desired wave is sufficiently large.

In a multi-rate compatible system, the received electric field strength varies depending on the signal transmission speed. for that reason,
In a system in which the cell coverage differs for each user, how to efficiently control the weight of the adaptive array antenna becomes a problem.

In a system in which a communication distance is secured by an antenna gain obtained by directing a beam of an adaptive antenna toward a mobile station, communication is impossible unless the antenna beam is directed toward the mobile station. Becomes In other words, if the mobile station is within the service area, it can receive signals without performing antenna beam control, but for mobile stations outside the service area, the antenna beam control Otherwise, no signal can be received. Information for performing antenna beam control is generated from a received signal. Therefore, the antenna gain obtained by directing the beam of the adaptive antenna in the direction of the mobile station, for a mobile station located far from the base station such that a communication path is secured, in order to perform antenna beam control There is a problem that necessary information cannot be obtained.

[0015]

As described above, in the next-generation wireless communication system, a signal transmission speed of several Mbps to several tens Mbps is assumed to be supported, and the occupied bandwidth per channel is set wide. For this reason, it is essential to improve the frequency use efficiency. In addition, since available frequency resources are limited, a frequency assignment method and a cell assignment method in a cellular system are technical issues.

Furthermore, the wider the variable range of cell coverage in a dynamic cell configuration system, the greater the flexibility of the system. Therefore, it is a technical problem how to extend the variable range of cell coverage. In addition, the extension of the coverage is closely related to the cell arrangement method in the cellular system.
That is, the interference to the neighboring cells should not increase as the cells are expanded. For this reason, the cell arrangement method in the dynamic zone configuration is a technical problem.

Further, to improve the frequency use efficiency,
In a system using an adaptive antenna,
A technical issue is how to efficiently control the weight of the adaptive array antenna. In addition, the antenna gain obtained by directing the beam of the adaptive antenna toward the mobile station provides information necessary for performing antenna beam control for a mobile station located at a position where a communication path is secured. There is also a problem that it cannot be obtained. In other words, how to grasp (initial capture) the initial position of the mobile station is a technical problem.

Accordingly, an object of the present invention is to provide an ASIC and an FP
It is an object of the present invention to provide a hybrid integrated circuit that can change or adjust specifications by combining GAs and has sufficient performance.

Another object of the present invention is to provide an ASIC and an FP.
An object of the present invention is to provide a new type of embedded integrated circuit capable of effectively utilizing a redundant portion of an FPGA by combining GAs.

[0020]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a transmission device, a reception device, and a base station equipped with the same, in which a variable range of coverage in a dynamic cell configuration system is provided. The purpose is to do.

Another object of the present invention is to provide a transmitting apparatus, a receiving apparatus, and a base station equipped with the same, which can prevent interference between adjacent cells even in a cell arrangement where available frequency resources are limited. To provide.

Still another object of the present invention is to provide an adaptive antenna beam for a mobile station located at a position where a communication path is secured by an antenna gain obtained by directing the beam of the adaptive antenna toward the mobile station. An object of the present invention is to provide a transmitting device, a receiving device, and a base station equipped with these devices, which enable control.

To achieve the above object, according to one aspect of the present invention, a transmitting apparatus that uses orthogonal frequency division multiplexing modulation and spectrum spreading selectively transmits orthogonal information signals to an information signal to be transmitted. An orthogonal frequency division multiplex modulation circuit for performing multiplex modulation, a spectrum spread circuit for selectively performing spread spectrum on the output of the information signal, and the information signal modulated by the orthogonal frequency division multiplex modulation or the spread spectrum. A transmission processing circuit for transmitting to a receiving device as a transmission signal, wherein the receiving device and the transmitting device are located in close proximity to each other and the reception is performed when the spread spectrum is not performed and the orthogonal frequency division multiplex modulation is performed. When the signal level is sufficient to effect communication between the receiving device and the transmitting device, the orthogonal frequency division multiplexing modulation circuit Performing the orthogonal frequency division multiplexing modulation of the information signal, the spread spectrum circuit does not spread the information signal, the receiving device and the transmitting device are at remote locations, the spread spectrum is not performed and the orthogonal When the received signal level when the frequency division multiplex modulation is performed is insufficient to perform communication between the reception device and the transmission device, the orthogonal frequency division multiplex modulation circuit includes the orthogonal frequency division multiplex modulation. And the spread spectrum circuit spreads the spectrum of the output of the orthogonal frequency division multiplex modulation circuit.

According to a preferred embodiment, the information signal is provided as a serial signal, and the orthogonal frequency division multiplex modulation circuit includes a serial-parallel converter for converting the information signal from serial to parallel, A modulator that maps the converted information signal to a symbol in the frequency domain, an inverse fast Fourier transformer that performs an inverse fast Fourier transform on the mapped information signal, and serially converts the inverse fast Fourier transformed information signal from parallel to serial. A parallel-to-serial converter for conversion.

Further, according to a preferred embodiment, the spread spectrum circuit is provided with a spread spectrum signal generating circuit for generating a plurality of spread spectrum signals.

Further, according to a preferred embodiment, the transmission processing circuit includes an adaptive array antenna, the receiving device and the transmitting device are located at remote positions, and a gain by the orthogonal frequency division multiplexing modulation is increased by the receiving device. When it is insufficient to perform communication with the transmitting device, the output from the spread spectrum circuit, by the transmitted signal of the spread spectrum, the direction of the receiving device with respect to the transmitting device is detected, the By directing the beam of the adaptive array antenna toward the mobile station, the received signal level of the receiving device is increased, and communication between the receiving device and the transmitting device by the orthogonal frequency division multiplex modulation is enabled.

According to another aspect of the present invention, a transmitting apparatus that uses orthogonal frequency division multiplexing modulation and spectrum spreading simultaneously performs an orthogonal frequency division multiplexing modulation on an information signal to be transmitted. A division multiplex modulation circuit, a spread spectrum circuit for selectively performing spread spectrum on an output of the orthogonal frequency division multiplex modulation circuit, and a transmission processing circuit for transmitting an output of the spread spectrum circuit as a transmission signal to a receiver. And wherein the receiving apparatus and the transmitting apparatus are in close proximity, the received signal level when the first orthogonal frequency division multiplexing modulation is not performed and the first orthogonal frequency division multiplex modulation is performed, When sufficient to communicate with the device, the orthogonal frequency division multiplex modulation circuit performs the first orthogonal frequency division multiplex modulation, The spreading circuit does not perform spread spectrum on the output of the orthogonal frequency division multiplex modulation circuit, the receiving apparatus and the transmitting apparatus are located at remote positions, the spread spectrum is not performed, and the first orthogonal frequency division multiplex modulation is performed. When the received signal level when performed is insufficient for performing communication between the receiving apparatus and the transmitting apparatus, the orthogonal frequency division multiplex modulation circuit includes a bandwidth for the first orthogonal frequency division multiplex modulation. A second orthogonal frequency division multiplex modulation having a narrower bandwidth is performed, and the spread spectrum circuit spreads the spectrum of the output of the orthogonal frequency division multiplex modulation circuit.

According to a preferred embodiment, the orthogonal frequency division multiplexing and modulation circuit also performs phase modulation of the information signal.

Further, according to another aspect of the present invention, a transmitting apparatus using both orthogonal frequency division multiplexing and spectrum spreading transmits an information signal to be transmitted for the first orthogonal frequency division multiplexing modulation in a frequency domain. A mapping circuit that maps to symbols, a spread spectrum circuit that selectively performs spread spectrum on an output signal from the mapping circuit, and an output signal from the spread spectrum circuit,
An orthogonal frequency division multiplex modulation circuit that performs the first orthogonal frequency division multiplex modulation, and a transmission processing circuit that transmits an output of the orthogonal frequency division multiplex modulation circuit as a transmission signal to a reception device; When the transmitting device is in the proximity position, the received signal level when the first orthogonal frequency division multiplex modulation is not performed and the first orthogonal frequency division multiplexing is performed, the communication between the receiving device and the transmitting device is performed. When it is sufficient, the orthogonal frequency division multiplex modulation circuit performs the first orthogonal frequency division multiplex modulation, and the spread spectrum circuit does not perform spread spectrum on the output signal from the mapping circuit and does not perform the spread spectrum operation. The apparatus is located at a remote location, and the received signal level is higher when the spread spectrum is not performed and the first orthogonal frequency division multiplex modulation is performed. When there is insufficient communication between the receiving apparatus and the transmitting apparatus, the orthogonal frequency division multiplex modulation circuit has a second bandwidth that is smaller than the bandwidth of the first orthogonal frequency division multiplex modulation. While performing orthogonal frequency division multiplexing modulation, the spread spectrum circuit spreads the spectrum of the output signal from the mapping circuit.

According to a preferred embodiment, the transmission processing circuit includes an adaptive array antenna, the receiving device and the transmitting device are located at remote positions, and a gain by the orthogonal frequency division multiplexing modulation is reduced by the receiving device. When it is insufficient to perform communication with the transmitting device, the output from the spread spectrum circuit, by the transmitted signal of the spread spectrum, the direction of the receiving device with respect to the transmitting device is detected, the By directing the beam of the adaptive array antenna toward the mobile station, the reception signal level of the receiving device is increased, and the communication between the receiving device and the transmitting device by the first orthogonal frequency division multiplex modulation is enabled. .

Further, according to another aspect of the present invention, a receiving apparatus that uses orthogonal frequency division multiplexing demodulation and despreading in the frequency domain with respect to an information signal transmitted from a transmitting apparatus and received by the receiving apparatus. An inverse spread spectrum circuit for selectively performing inverse spread, and an orthogonal frequency division multiplex demodulation circuit for performing orthogonal frequency division multiplex demodulation on the information signal, wherein the receiving device and the transmitting device are in close proximity. ,
When the received signal level in the case where the despreading is not performed and the orthogonal frequency division multiplex demodulation is performed is sufficient to perform communication between the receiving apparatus and the transmitting apparatus, the despread spectrum circuit performs reception. Does not perform the despreading of the information signal, and the orthogonal frequency division multiplex demodulation circuit performs the orthogonal frequency division multiplex demodulation of the received information signal, the receiving device and the transmitting device are at remote positions, When despreading is not performed and the gain due to the orthogonal frequency division multiplex demodulation is insufficient to perform communication between the receiving device and the transmitting device, the despreading circuit despreads the received information signal. In addition, the orthogonal frequency division multiplex demodulation circuit does not perform the orthogonal frequency division multiplex demodulation of the received information signal.

According to a preferred embodiment, the orthogonal frequency division multiplex demodulation circuit also performs phase demodulation of the information signal.

Further, according to another aspect of the present invention, a receiving apparatus that uses both orthogonal frequency division multiplexing demodulation and despreading transmits a first orthogonal signal to an information signal transmitted from a transmitting apparatus and received by the receiving apparatus. An orthogonal frequency division multiplexing demodulation circuit for performing frequency division multiplexing demodulation; an inverse spectrum spreading circuit for selectively performing despreading on an output of the orthogonal frequency division multiplexing and demodulation circuit in a frequency domain; A demapping circuit for demapping the despread signal in the frequency domain for multiplex demodulation, wherein the receiving device and the transmitting device are in close proximity, do not perform the despreading, and When the received signal level when the orthogonal frequency division multiplex demodulation is performed in the first bandwidth is sufficient to perform communication between the receiving apparatus and the transmitting apparatus, the orthogonal frequency division multiplexing is performed. The tuning circuit performs the first orthogonal frequency division multiplex demodulation of the received information signal, and the despread spectrum circuit does not perform the despreading of the received information signal, and the receiving device and the transmitting device are remote from each other. In position,
When the received signal level in the case where the despreading is not performed and the first orthogonal frequency division multiplex demodulation is performed is insufficient for performing communication between the receiving apparatus and the transmitting apparatus, the orthogonal frequency The division multiplex demodulation circuit executes a second orthogonal frequency division multiplex demodulation having a bandwidth smaller than the bandwidth of the first orthogonal frequency division multiplex demodulation, and the inverse spread spectrum circuit performs the orthogonal frequency division multiplex demodulation circuit. Despread the output of

Further, according to another aspect of the present invention, a receiving apparatus that uses both orthogonal frequency division multiplexing demodulation and despreading performs orthogonal frequency division multiplexing on an information signal transmitted from a transmitting apparatus and received by the receiving apparatus. An orthogonal frequency division multiplexing demodulation circuit for demodulation, an inverse spectrum spreading circuit for selectively despreading a received information signal, and selectively demapping the orthogonal frequency division multiplexed demodulated signal in a frequency domain. A receiving signal level when the receiving device and the transmitting device are in close proximity to each other, and the despreading is not performed and the orthogonal frequency division multiplex demodulation is performed. When sufficient for communication with the transmitting device, the orthogonal frequency division multiplex demodulation circuit performs the orthogonal frequency division multiplex demodulation of a received information signal, and The despread spectrum circuit does not despread the output of the orthogonal frequency division multiplex demodulation circuit, the receiving device and the transmitting device are at remote locations, does not perform the despreading, and performs the orthogonal frequency division multiplex demodulation. When the received signal level in the case where the reception signal level is insufficient to perform communication between the reception apparatus and the transmission apparatus, the orthogonal frequency division multiplex demodulation circuit does not perform the orthogonal frequency division multiplex demodulation and performs the inverse The spread spectrum circuit despreads the received information signal.

Further, according to a preferred embodiment, the inverse spread spectrum circuit is provided with a spread spectrum signal generating circuit for generating a plurality of spread spectrum signals.

Further, according to a preferred embodiment, the orthogonal frequency division multiplex demodulation circuit converts the information signal from serial to parallel, and performs a fast Fourier transform of the parallel converted information signal. At least a fast Fourier transformer is provided.

Further, according to a preferred embodiment, the inverse spread spectrum circuit changes a generated spread spectrum signal for each transmission device.

Further, in accordance with another aspect of the present invention, a base station communicating with at least one mobile station in the area in charge using orthogonal frequency division multiplexing modulation and spread spectrum is used for the first transmission. A first transmission mode for transmitting a signal having a speed and a first gain, and a signal having a second transmission speed lower than the first transmission speed and a second gain higher than the first gain. A transmission device having a second transmission mode for transmitting, a first reception mode for receiving a signal transmitted in the first transmission mode, and receiving a signal transmitted in the second transmission mode A receiver provided with a second reception mode, wherein the mobile station and the base station are located in close proximity, and communication is maintained by the first transmission mode and the first reception mode. , The base station comprises:
Communication is performed in the first transmission mode and the first reception mode, and the mobile station and the base station are at remote locations, and communication cannot be maintained in the first transmission mode and the first reception mode. In this case, the base station performs communication in the second transmission mode and the second reception mode.

According to a preferred embodiment, in the area belonging to both the area served by the base station and the area served by another adjacent base station having the same configuration, the second transmission Communication is performed according to the mode and the second reception mode.

Further, according to a preferred embodiment, the first transmission mode and the first reception mode of the base station correspond to the first transmission mode of another adjacent base station having the same configuration. And using the same communication resources as the first reception mode and the second transmission mode of the base station.
And the second transmission mode and the second reception mode of another adjacent base station having the same configuration use different communication resources.

Further, according to a preferred embodiment, the transmitting device includes an adaptive array antenna, wherein the base station and the mobile station are located at remote positions, and wherein the first transmission mode and the first reception mode are provided. If the gain due to is insufficient to perform communication between the base station and the mobile station, the second
The base station and the mobile station perform communication by the transmission mode and the second reception mode, detect the direction of the mobile station with respect to the base station, and output the transmission output to the mobile station by the adaptive array antenna. Increase the gain of the first transmission mode and the first reception mode, and then perform communication between the base station and the mobile station in the first transmission mode and the first reception mode .

[0042]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

(First Embodiment) FIG. 1 is a block diagram showing a configuration of a transmitting apparatus and a receiving apparatus according to a first embodiment of the present invention. The transmitting device and the receiving device according to the first embodiment of the present invention provide an OFDM (Orthogonal F
Radio communication is performed using a modulation scheme (requency division multiplexing).

As shown in FIG. 1, a transmitting apparatus 10a according to a first embodiment of the present invention includes a serial-parallel converter 12 for converting an information signal (data stream) to be transmitted from a serial stream to a parallel stream. , A modulator 14 that maps parallel data output from the serial-parallel converter 12 in the frequency domain, and an IFFT (Inverse Fast Fourier) that converts the frequency domain signal output from the modulator 14 into a time domain signal.
Transform, inverse fast Fourier transform) processor 16 and IF
A parallel-to-serial converter 18 that converts the output sequence of the FT processor 16 from a parallel sequence to a serial sequence, a spread spectrum circuit 20 that spreads the spectrum of the output signal of the parallel-serial converter 18, and an output of the spread spectrum circuit 20. A guard interval adding circuit 22 for adding a guard interval which is a time gap for preventing multipath interference to a signal, and a transmission processing circuit for performing processing for transmitting an output signal of the guard interval adding circuit 22 as a radio signal 24, and at least an antenna 26 that radiates an output signal of the transmission processing circuit 24 as radio waves. Here, the transmission processing circuit 24 performs conversion of the input signal from a digital signal to an analog signal, conversion of a frequency to a predetermined radio frequency, amplification of signal power to a predetermined signal power, and the like. .

Further, transmitting apparatus 10a according to the first embodiment is provided in spread spectrum circuit 20, and when spread spectrum circuit 20 performs spread spectrum,
A pattern generation circuit 44a for generating a spread spectrum signal (pattern) multiplied by the output signal of the parallel-to-serial converter 18; and a serial / parallel circuit provided in the modulator 14 when the spread spectrum circuit 20 performs spread spectrum. Converter 1
It has a mapping setting section 46 for setting the number to be mapped out of the parallel data output from 2.
Although not shown, the transmission circuit 10a includes a control circuit that controls whether or not the spread spectrum circuit 20 performs spread spectrum. The control circuit outputs a predetermined control signal to the spread spectrum circuit 20, and controls the spread spectrum processing of the spread spectrum circuit 20 according to the control signal.

On the other hand, the receiving apparatus 10b according to the first embodiment of the present invention includes an antenna 28 for receiving a radio wave radiated from the transmitting apparatus 10a, and a process for converting a received radio signal into a baseband. Reception processing circuit 3 that performs processing
0, a guard interval elimination circuit 32 that divides the guard interval according to the timing information obtained from the demodulated signal, an inverse spectrum spreading circuit 34 that performs inverse spectrum spreading on the output signal of the guard interval elimination circuit 32, Serial-to-parallel converter 36 for converting the output signal of spread spectrum circuit 34 from a serial column to a parallel column
And an FFT (Fa) for converting the parallel data output from the serial / parallel converter 36 from a time domain signal to a frequency domain signal.
st Fourier Transform, Fast Fourier Transform) Processor 38
And a demodulator 40 for demapping the frequency signal output from the FFT processor 38 in the frequency domain, and a parallel / serial converter 42 for converting the output signal of the demodulator 40 from a parallel sequence to a serial sequence.

Further, the receiving apparatus 10b according to the first embodiment is provided in an inverse spread spectrum circuit 34,
A pattern generation circuit 44b that generates the same pattern as the pattern used by the spread spectrum circuit 20 of the transmitting device 10a when the reverse dispersing circuit 34 performs reverse spread spectrum.
And a demapping setting unit 47 provided in the demodulator 40 and configured to set the same number of demappings as the number of mappings set by the mapping setting unit 46 of the transmission device 10a. Although not shown, the transmission device 10
Similarly to a, the receiving circuit 10b includes a control circuit that controls whether or not the inverse spread spectrum circuit 34 performs the inverse spread spectrum. This control circuit outputs a predetermined control signal to the inverse spread spectrum circuit 34, and controls the inverse spread spectrum processing of the inverse spread spectrum circuit 34 according to the control signal.

Next, a cell configuration and a burst frame configuration according to the first embodiment of the present invention will be described.
First, a general cellular configuration and burst frame configuration of the cellular system will be described. FIG. 2 shows an example of a general cellular system cell configuration. As shown in FIG. 2, in a general cellular system, in a service area,
A plurality of base stations 48n-1, 48n, 48n + 1 are arranged, and ranges (cells) 50n-1, 50n, 50n + 1 to which radio waves from each base station 48n-1, 48n, 48n + 1 reach.
Covers the service area. Base station 48n-1,4
8n and 48n + 1 are cells 50n-1 and 50n, respectively.
It manages resources such as radio frequencies in n and 50n + 1. Further, within the service area, a plurality of mobile stations 52 m
-1, 52m, and 52m + 1 exist. Each base station 48m
-1,48m, 48m + 1 and each mobile station 52m-1,
52m and 52m + 1 include a general transmitting device and a general receiving device.

As described above, the base stations 48n-1, 48n,
48n + 1 and mobile stations 52n-1, 52n, 52n +
A system adopting a system configuration in which a radio resource to be used is assigned to one is generally referred to as a “cellular system”. The timing of signals transmitted and received in this communication system depends on the channel allocation scheme employed in the communication system.

FIG. 3 shows an example of a TDMA burst frame configuration in which time-division multiplexed slots are allocated. In FIG. 3, the horizontal axis indicates time. The burst frame in FIG. 3 includes a broadcast channel 54 used for transmission from the base station to all mobile stations, a downlink channel 56 used for transmission from the base station to a specific mobile station, and a burst channel 56 used for transmission from the base station to the base station. An uplink channel 58 used for transmission, and a random access channel 60 used for requesting radio resource allocation from the mobile station to the base station. Each of the channels 54, 56, 58, 60 comprises a plurality of slots.

A mobile station existing in the service area communicates with the base station using specific slots of the downlink channel 56 and the uplink channel 58 allocated by the base station. In a conventional cellular system, a modulation system and a signal transmission rate used in communication between a base station and a mobile station are often determined in advance. For example, in a PHS system, the modulation scheme is π / 4 shift QP
The SK and signal transmission speed are defined as 32 kbps. On the other hand, next-generation wireless communication systems aiming at accommodating multimedia information are designed to accommodate users with different signal transmission rates in order to support different QoS. Specifically, by changing the modulation scheme and coding rate, accommodating users with different signal transmission rates is realized. That is, a multi-rate compatible system is adopted in the next-generation wireless communication system.

The multi-rate compatible system is suitable for accommodating multimedia information because it can accommodate users with different signal transmission rates. Further, since the signal transmission speed can be set according to the wireless propagation environment, the frequency utilization efficiency can be improved. Further, by changing the signal transmission speed, it is possible to change the cell coverage.
The greater the variable range of cell coverage in a dynamic cell configuration system, the greater the system flexibility. Therefore, as described in the related art, it is a technical problem how to extend the variable range of cell coverage.

Next, the configuration of a cell in the base station according to the first embodiment of the present invention will be described using FIG. FIG. 4 is a diagram explaining cell coverage of the base station according to the first embodiment of the present invention. As shown in FIG. 4, the base station 62 according to the first embodiment of the present invention has a normal coverage 66 and a spreading coverage 68 as cell coverage. Normal coverage 66
Is the cell coverage when the base station 62 performs conventional OFDM transmission, and the mobile stations 64a and 64b located within the normal coverage 66 can perform conventional OFDM transmission. Further, the base station 62 according to the first embodiment of the present invention has a spreading coverage 78 outside the coverage 66 for performing the conventional OFDM transmission, and the mobile station 64c existing in the spreading coverage 68. Wireless communication with the device.

As shown in FIG. 1, a transmitting apparatus 10a according to the first embodiment of the present invention has a spread spectrum circuit 20 between a parallel / serial converter 18 and a guard interval adding circuit 22, The receiving device 10b has an inverse spread spectrum circuit 34 between the guard interval removing circuit 32 and the serial-parallel converter 36, respectively. Transmission device 10
The spread spectrum circuit 20a spreads the transmission signal by multiplying the transmission signal by the pattern generated by the pattern generation circuit 44a. Further, the spread spectrum circuit 34 applies a pattern generation circuit 44b to the spread spectrum received signal.
Is multiplied by the pattern generated by the above, and the spread spectrum received signal is despread. The pattern multiplied by the spread spectrum circuit 20 and the pattern multiplied by the inverse spread spectrum circuit 34 are the same.

FIGS. 5 and 6 show the transmission device 10a of FIG.
FIG. 5 is a diagram for explaining a signal flow in the receiving apparatus 10b. FIG. 5 shows a case where spread spectrum and inverse spread spectrum are not performed, and FIG. 6 shows a case where spread spectrum and inverse spread spectrum are performed. The case where the spread spectrum and the inverse spread spectrum are not performed means that the gain is obtained when the receiving apparatus and the transmitting apparatus are close to each other, the spread spectrum is not performed, and the orthogonal frequency division multiplex modulation is performed. This is the case when it is enough to communicate with. In the case where spread spectrum and inverse spread spectrum are performed, the receiving apparatus and the transmitting apparatus are located at remote positions, the spread spectrum is not performed, and the gain by the orthogonal frequency division multiplex modulation makes the communication between the receiving apparatus and the transmitting apparatus. This is when there is not enough to do. As shown in FIG. 5, when the spread spectrum is not performed, the transmitting apparatus 10a
Generates a normal OFDM signal. Specifically, a normal OFDM signal is generated by the modulator 14 of the transmitting apparatus 10a performing complex mapping of the code in the frequency domain (see the spectrum 70) and converting the IFFT processor 18 into the time domain. This OFDM signal will have available occupied bandwidth. Since the spread spectrum circuit 20 outputs the input signal as it is, as a result, the transmitting apparatus 10a outputs a signal having the spectrum 74.

As shown in FIG. 6, even when performing spread spectrum, transmitting apparatus 10a generates an OFDM signal. However, the modulator 14 sets a small number of codes for complex mapping in the frequency domain (see spectrum 80).
Here, only one subcarrier is modulated, and the remaining subcarriers are set as null. In effect,
This means that the process of orthogonal frequency division multiplexing has not been performed. Therefore, the OFDM signal converted into the time domain by the IFFT processor 16 has the spectrum 82. Assuming that the number of available subcarriers of the OFDM signal is N, the band of the spectrum 82 is 1 / N of the available occupied bandwidth. Therefore, the transmission speed is also N
It will be a fraction. The spread spectrum circuit 20
Multiplies the input signal by a predetermined pattern. The transmission processing circuit 24 amplifies the signal to a predetermined power and outputs the signal. Accordingly, the transmitting apparatus 10a outputs a spread spectrum OFDM signal having the same spectrum 84 as the spectrum 74 in FIG.

On the other hand, receiving apparatus 10b normally does not perform inverse spread spectrum (see FIG. 5), but performs inverse spread spectrum only when reception is not possible. As shown in FIG.
When performing inverse spectrum spreading, the inverse spectrum spreading circuit 34 of the receiving device 10b sequentially switches a plurality of predetermined patterns to the received signal (see the spectrum 86), and switches the same pattern as the pattern used by the transmitting device 10a. Search for patterns. Then, the inverse spread spectrum circuit 34 performs the inverse spread spectrum using the same pattern as that of the transmitting apparatus 10a. Therefore, the receiving device 10b obtains a signal having the spectrum 88. The spectrum 88 of this signal is the same as the spectrum 78 without inverse spread spectrum.

According to the first embodiment of the present invention, since a normal OFDM signal is spread and transmitted and despread at the receiving side, the minimum receiving sensitivity can be improved by the amount of the spreading gain. For this reason, it is possible to extend the variable range of the coverage in the dynamic cell configuration system.

Further, according to the first embodiment of the present invention, since the present invention can be implemented by partially changing the existing system, the initial cost at the time of introduction can be reduced.

(Second Embodiment) FIG. 7 is a block diagram showing a configuration of a transmitting apparatus and a receiving apparatus according to a second embodiment of the present invention. The transmitting device and the receiving device according to the second embodiment of the present invention also perform wireless communication using the OFDM modulation method. The transmitting apparatus and the receiving apparatus according to the first embodiment of the present invention do not perform both OFDM modulation and spread spectrum on the same signal. However, in the present embodiment, both OFDM modulation and spectrum spreading are performed on the same signal.

In the first embodiment, an example of a configuration in which spectrum spreading and inverse spectrum spreading are performed on a signal in the frequency domain is shown. Therefore,
1 is connected between the parallel / serial converter 18 and the guard interval adding circuit 22, and the inverse spread spectrum circuit 34 is connected between the guard interval removing circuit 32 and the serial-parallel conversion circuit 36. Have been.
However, the spread spectrum operation and the inverse spread spectrum operation are linear operations, and therefore can be performed in the time domain. In the present embodiment, spread spectrum and inverse spread spectrum are performed in the time domain.

As shown in FIG. 7, a transmitting apparatus 10a according to a second embodiment of the present invention includes a serial / parallel converter 12 for converting an information signal (data stream) to be transmitted from a serial stream to a parallel stream. , A modulator 14 that maps parallel data output from the serial-parallel converter 12 in the frequency domain, a spread spectrum circuit 140 that spreads the spectrum of the output signal of the modulator 14, and a signal that is output from the spread spectrum circuit 140. IFFT (Inverse Fast Fourier Transform) for converting a frequency domain signal into a time domain signal
m, inverse fast Fourier transform) processor 16, a parallel-to-serial converter 18 for converting the output sequence of the IFFT processor 16 from a parallel sequence to a serial sequence, and preventing multipath interference in the output signal of the parallel-serial converter 18. A guard interval adding circuit 22 for adding a guard interval which is a temporal gap for transmission, a transmission processing circuit 24 for performing processing for transmitting an output signal of the guard interval adding circuit 22 as a radio signal, and a transmission processing circuit 24. An antenna 26 that radiates an output signal as a radio wave. Here, the transmission processing circuit 24 converts the input signal from a digital signal to an analog signal, converts a frequency to a predetermined radio frequency, amplifies signal power to a predetermined signal power,
And so on.

Further, the transmitting apparatus 10a according to the second embodiment is provided in a spread spectrum circuit 140,
When the spread spectrum circuit 140 performs spread spectrum, a pattern generation circuit 144a for generating a spread spectrum signal (pattern) to be multiplied with the output signal of the modulator 14, and the spread spectrum circuit 140 provided in the modulator 14. Of the parallel data output from the serial-parallel converter 12 when performing spread spectrum, has a mapping setting unit 46 for setting the number to be mapped. Although not shown, the transmission circuit 10a includes a control circuit that controls whether the spread spectrum circuit 140 performs spread spectrum. The control circuit outputs a predetermined control signal to the spread spectrum circuit 140, and the spread spectrum circuit 140
Control of the spread spectrum processing of.

On the other hand, the receiving apparatus 10b according to the second embodiment of the present invention includes an antenna 28 for receiving a radio wave radiated from the transmitting apparatus 10a, and a process for converting a received radio signal into a baseband band. Reception processing circuit 3 that performs processing
0, a guard interval removing circuit 32 for dividing the guard interval according to the timing information obtained from the demodulated signal, a serial-parallel converter 36 for converting the output signal of the guard interval removing circuit 32 from a serial column to a parallel column, FFT for converting parallel data output from the serial-parallel converter 36 from a time domain signal to a frequency domain signal
(Fast Fourier Transform) processor 38, inverse spectrum spreading circuit 142 for performing inverse spectrum spreading on the frequency signal output from FFT processor 38, and output signal of inverse spectrum spreading circuit 142 in the frequency domain. It comprises at least a demodulator 40 for demapping and a parallel / serial converter 42 for converting an output signal of the demodulator 40 from a parallel sequence to a serial sequence.

Further, the receiving apparatus 10b according to the second embodiment is provided in an inverse spread spectrum circuit 142. When the inverse spread spectrum circuit 142 performs inverse spread spectrum, the spread spectrum circuit 14 of the transmitting apparatus 10a is provided.
A pattern generation circuit 44b for generating the same pattern as the pattern used by the demodulator 40, and a demultiplexer for setting the same number of demappings as the number of mappings set by the mapping setting unit 46 of the transmitting apparatus 10a. A mapping setting unit 47. Although not shown,
Similarly to the transmitting apparatus 10a, the receiving circuit 10b includes a control circuit that controls whether or not the inverse spread spectrum circuit 142 performs the inverse spread spectrum. This control circuit outputs a predetermined control signal to the inverse spread spectrum circuit 142, and controls the inverse spread spectrum processing of the inverse spread spectrum circuit 142 according to the control signal.

FIGS. 8 and 9 show the transmission device 10a of FIG.
8 is a diagram for explaining the flow of signals in the receiving apparatus 10b. FIG. 8 shows a case where spread spectrum and inverse spread spectrum are not performed, and FIG. 9 shows a case where spread spectrum and inverse spread spectrum are performed. As shown in FIG. 8, when the spread spectrum is not performed, the transmitting apparatus 10
a generates a normal OFDM signal. Specifically, in a normal OFDM signal, the modulator 14 of the transmitting apparatus 10a performs complex mapping of the code in the frequency domain, and the spread spectrum circuit 140 outputs the input signal as it is (spectrum 1).
70). The IFFT processor 18 converts a frequency-domain signal that has not been spread spectrum into a time-domain signal. This OFDM signal will have available occupied bandwidth.

As shown in FIG. 9, also when performing spread spectrum, transmitting apparatus 10a generates an OFDM signal. However, the modulator 14 sets a small number of codes for complex mapping in the frequency domain (see spectrum 180). Here, only four subcarriers are modulated,
The remaining subcarriers are set as null. Therefore, the OFDM signal of the modulator 14 has a spectrum 180
Will have. Since the number of subcarriers substantially modulated in the OFDM signal is 4, if the total number of subcarriers is 64, the bandwidth of spectrum 180 is 1/16 of the available occupied bandwidth. Further, the spread spectrum circuit 20 multiplies the input signal by a predetermined pattern. Therefore, the output of the spread spectrum circuit 20 outputs an OFDM signal having the spectrum 182 and spread 16 times.

On the other hand, receiving apparatus 10b normally does not perform inverse spread spectrum (see FIG. 8), but performs inverse spread spectrum only when reception is not possible. As shown in FIG.
When performing inverse spread spectrum, the inverse spread spectrum circuit 142 of the receiving device 10b sequentially switches a plurality of predetermined patterns to the received signal (refer to the spectrum 186) and uses the same pattern as the pattern used by the transmitting device 10a. Search for patterns. Then, the inverse spread spectrum circuit 142 performs the inverse spread spectrum using the same pattern as that of the transmitting apparatus 10a. Therefore,
The receiving device 10b obtains a signal having the spectrum 188.

In the second embodiment of the present invention, the ordinary O
Since the FDM signal is spread and transmitted and despread at the receiving side, the minimum receiving sensitivity can be improved by the spread gain. For this reason, it is possible to extend the variable range of the coverage in the dynamic cell configuration system.

Further, similarly to the first embodiment of the present invention, the present invention can be implemented by partially changing the existing system, so that the initial cost at the time of introduction can be reduced. Which embodiment is adopted is selected in consideration of the environment, specifications, execution form, and the like.

(Third Embodiment) Next, the third embodiment of the present invention will be described.
An embodiment will be described. In a next-generation wireless communication system, a signal transmission speed of several Mbps to several tens Mbps is assumed to be supported, and an occupied bandwidth per channel is set wide. Since frequency resources are finite,
Efficient cell placement is important.

FIG. 10 shows an example of a conventional cell arrangement when one available frequency is used. As shown in FIG. 10, in order to use the same frequency, cells 92n-1, 92n, 9
It becomes impossible to arrange 2n + 1 in an overlapping manner. Thus, for example, the mobile station 94a in the cell 92n-1 can be connected to the cell 92n via the location of the mobile station 94b.
When moving to the position of the mobile station 94c within +1, the base station 9
Communication with 0n-1, 90n + 1 is temporarily interrupted.
This is an important problem for the mobile communication system, and it is desired to reliably realize handover even when the number of available frequencies is small.

FIG. 11 shows a cell arrangement according to the third embodiment of the present invention. The third embodiment of the present invention provides a base station and a mobile station equipped with the transmitting device and the receiving device according to the first embodiment for a cell arrangement in a case where the number of usable frequencies is one. This is an example of application. That is, in the third embodiment of the present invention, by using the transmission device and the reception device of the first embodiment, the coverage of the cell of each base station is expanded, and the adjacent cells are overlapped. It is possible to dispose them. Note that, here, for simplification of the description, the description will be made assuming that there are two base stations.

As shown in FIG. 11, in the cell arrangement according to the third embodiment of the present invention, each base station 96n-
The 1,96n cells are the same as in the first embodiment described above.
It has normal coverages 98n-1 and 98n and diffusion coverages 100n-1 and 100n, respectively. The normal coverages 98n-1 and 98n are coverages for performing the conventional OFDM transmission, and include the spread coverage 100n.
n-1 and 100n are coverages when the transmission distance is extended by the spreading gain.

The mobile station 102a which is located in the normal coverage 98n-1 and the mobile station 102c which is located in the normal coverage 98n are provided with spread coverages 100n-1 and 100n.
It is possible to perform higher-speed transmission than the mobile station 102b located in the area. Here, the mobile station 102b is connected to the base station 9
6n-1 spread coverage 100n-1, base station 96n
Belong to both the diffusion coverages 100n. That is, the mobile station 102b communicates with the base station 96n-1 and the base station 96n.
n can be received. The base station 96n-1 and the base station 96n use the same frequency, but by changing the pattern (spread spectrum signal) used in the spread spectrum and the inverse spread spectrum, the mobile station 102b receives the signal from both. Can be separated.

According to the third embodiment of the present invention, even when adjacent cells use the same frequency, it is possible to avoid the problem of interference due to extension of cell coverage. Furthermore, according to the third embodiment of the present invention, handover can be realized even in a cell configuration where the number of available frequencies is small.

Next, a burst frame configuration according to the third embodiment of the present invention will be described using FIG. 11 and FIG. FIG. 12 is a diagram illustrating a burst frame configuration according to the third embodiment of the present invention. The burst frame configuration according to the third embodiment basically includes a TD for allocating time-division multiplexed slots shown in FIG.
This is the same as the burst frame configuration of the MA system.

As shown in FIG. 12, the burst frame configuration according to the third embodiment of the present invention employs a broadcast channel 104 used for transmission from a base station to all mobile stations.
Downlink channel 106 used for transmission from a base station to a specific mobile station, uplink channel 108 used for transmission from a mobile station to a base station, random access used for requesting radio resource allocation from a mobile station to a base station Channel 1
And 10. Each channel 104, 106, 1
Each of 08 and 110 consists of a plurality of slots.

Further, in the third embodiment of the present invention,
In order to extend the cell coverage of the base station without affecting the normal OFDM transmission, the downlink channel 1
In 06 and the upstream channel 108, an OFDM signal subjected to spread spectrum is transmitted. That is, FIG.
As shown in (1), an OFDM signal subjected to spread spectrum is inserted into slots 112 and 114 constituting the downlink channel 106 and the uplink channel 108.

For example, as shown in FIG. 11, mobile stations 102a, 1a located in normal coverage 98n-1, 98n
02c treats the signals transmitted in slots 112 and 114 as slots assigned to different mobile stations. Therefore, the presence of this signal indicates that the normal OFDM
It does not affect transmission.

On the other hand, the diffusion coverages 100n−1, 10n
0n, the mobile station 102b reverses the signals transmitted in the slots 112 and 114 by using the same pattern as the pattern used by the base stations 96n-1 and 96n that generated the signals for spread spectrum. Spread. Therefore, the mobile station 102b can recover the signals transmitted in the slots 112 and 114.

The mobile station 102b is also connected to the mobile station 1
In order to provide services similar to those of the mobile stations 102a and 102c, the mobile station 102b also needs to provide a broadcast channel, a downlink channel used for transmission from the base station to a specific mobile station, and an uplink channel used for transmission from the mobile station to the base station. It is necessary to provide a channel, a random access channel used for a request for radio resource allocation from the mobile station to the base station. Furthermore, it will be appreciated that these signals are normally OFD
M transmission must not be affected. Therefore, a broadcast channel, a downlink channel, an uplink channel, and a random access channel are provided to the mobile station 102b using the slots 112 and 114 of the downlink channel 106 and the uplink channel 108 in FIG.

Since the spread spectrum OFDM signal is transmitted on the downlink channel 106 and the uplink channel 108 which are user channels, the downlink channel 1
It is uncertain which slot of the channel 06 and the uplink channel 108 is allocated. That is, from the beginning of the burst frame in FIG.
The number of slots until the timing at which the DM signal is transmitted is
Not constant.

Therefore, in the third embodiment of the present invention,
In the broadcast channel for mobile stations located in the normal coverages 98n-1 and 98n, the OFD spectrum-spread in the downlink channel from the beginning of the burst frame.
The number of slots I until the timing at which the M signal is transmitted, and the spread spectrum coverages 100n-1, 100n
The number of slots II up to the timing at which the OFDM signal spread in the uplink channel is transmitted to the mobile station 102b located in the mobile station 102b, and burst frame synchronization can be achieved smoothly even if the spread coverage is entered. .

More specifically, according to the third embodiment of the present invention, first, the mobile station existing in the normal coverage receives a slot other than the slots 112 and 114. When the mobile station moves from normal coverage to spread spectrum coverage, data cannot be restored from normal OFDM signals. The inverse spread spectrum circuit 142 of the receiving device 10b sequentially switches a plurality of predetermined patterns for all slots of the downlink channel 106 and the uplink channel 108, and searches for the same pattern as the pattern used by the transmitting device 10a. At the same time, the positions of the slots 112 and 114 are specified. Then, data is extracted from the slots 112 and 114.

The extracted data is combined and
A TDMA-type burst frame to which time-division multiplexed slots are allocated as shown in FIG. As shown here, a broadcast channel 104 used for transmission from a base station to a mobile station existing in spread spectrum coverage, a downlink channel 106 used for transmission from a base station to a specific mobile station, An uplink channel 108 used for transmission to a station, and a random access channel 110 used for a request for radio resource allocation from a mobile station to a base station. Each channel 1
Each of 04, 106, 108 and 110 consists of a plurality of slots. That is, in the spread spectrum coverage, a channel independent of the normal coverage is provided, and radio resources are allocated therein.

In the broadcast channel, the OFD spectrum-spread from the beginning of the burst frame
The number of slots I up to the timing at which the M signal is transmitted, and the spread spectrum coverages 100n-1 and 100n
The number of slots II up to the downlink channel and the uplink channel for the mobile station 102b located in the area is transmitted to achieve burst frame synchronization. Therefore, once the communication with the spread spectrum coverage is established, the OFDM spread in the downlink channel from the head of the burst frame is started.
The number of slots I until the timing when the DM signal is transmitted,
And spread spectrum coverage 100n-1, 100
n for the mobile station 102b located in the n-th mobile station 102b even if the number of slots II until the timing at which the OFDM signal spread in the uplink channel is transmitted is changed.
It is not necessary to search for the same pattern as the pattern used by Oa and repeat the process of specifying the positions of slots 112 and 114.

The above configuration is effective in minimizing the change of the existing system. However, to make the control more rational, the spread spectrum O
The timing at which the FDM signal is transmitted is determined by the downlink channel 1
06 and the head of the uplink channel 108. In this case, processing for detecting the positions of the slots 112 and 114 and processing for notifying the number of slots I and the number of slots II are not required.

According to the third embodiment of the present invention, it is possible to extend the cell coverage of the base station without affecting normal OFDM transmission.

Further, in the third embodiment of the present invention, since a different spread spectrum signal is used for each base station,
It is possible to prevent interference with adjacent cells using the same frequency. This is particularly useful when available frequency resources are limited.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described.
An embodiment will be described. The fourth embodiment is an example in which the transmitting apparatus and the receiving apparatus according to the first and third embodiments are provided with an adaptive antenna device. The intelligent antenna technology is described in the prior art document "Intelligent antenna technology", "Study of zone generation algorithm in adaptive variable zone configuration system", "Study of adaptive zone configuration system using directional antenna for base station". Is effective in improving the channel utilization efficiency as shown in FIG.

FIG. 13 is a block diagram showing a configuration of a receiving antenna apparatus according to the fourth embodiment of the present invention. As shown in FIG. 13, the receiving antenna device according to the fourth embodiment of the present invention includes a plurality of antenna elements 116-
, 116-k, and an antenna control unit 118 that controls a plurality of antenna elements 116
And the antenna control unit 118
0b. Then, the antenna control unit 118
A plurality of weighters 120-1, 120-2, 120 provided corresponding to the plurality of antenna elements 116, respectively.
-3,..., 120-k, a combiner 122 that combines the received signals of the antenna elements 116 weighted by the plurality of weighters 120, a plurality of weighters 120
Weight control section 124 for controlling a plurality of antenna elements 1
And an incoming wave estimating unit 126 for estimating the direction of the incoming wave from the 16 received signals.

In the receiving antenna apparatus according to the fourth embodiment of the present invention, first, the arriving wave estimating section 126 inputs the signals received by the antenna elements 116 and receives the signals based on the reception strength of each signal. Estimate the direction of the desired wave. For this estimation, an arrival direction estimation algorithm such as MUSIC or ESPRIT is used. Then, based on the estimation result, weight control section 124 controls the weight set in each weighter 120. In addition, MUSIC
For details, see IEEE, Trans., Vol.AP-32, No. 3, pp. 27
6-280 (Mar.1986) "Multiple Emitter Location and
Signal Parameter Estimation ”. For more information on ESPRIT, see IEEE, Trans., Vol.AS
SP-37, pp.984-995 (July 1989), "ESPRIT-Estimation
of Signal Parameters via Rotational Invariance Te
chniques ".

FIG. 14 shows a configuration of a transmitting antenna apparatus according to the fourth embodiment of the present invention. As shown in FIG. 14, the transmitting antenna apparatus according to the fourth embodiment of the present invention includes a plurality of antenna elements 128-1, 128-2, 1
, 128-1 and a plurality of antenna elements 12
8, an antenna control unit 130 for controlling
Antenna control section 130 is connected to each of transmitting apparatus 10a and receiving apparatus 10b. Then, the antenna control unit 130 includes a plurality of weighters 134-1 and 134- provided for each of the plurality of antenna elements 128.
, 134-3, a demultiplexer 136 that demultiplexes the transmission signal output from the transmission device 10a to each of the antenna elements 128, and a weight control unit 138 that controls the plurality of weighters 120. , Is provided corresponding to each of the antenna elements 128, and outputs the transmission signal weighted by the corresponding weighter 134 to the antenna element 128,
A plurality of circulators 132-1, which output a received signal input from the antenna element 128 to the receiving device 10 b,
132-2, 132-3,..., 132-1.

In the transmitting antenna device according to the fourth embodiment of the present invention, first, the duplexer 136 is connected to the transmitting device 10a.
Is demultiplexed, and each demultiplexed transmission signal is output to each weighting device 134. Weight control unit 1
38 controls the weight of each weighter 134 based on the control signal from the receiving device 10b. Receiving device 10b
Generates the control signal based on the estimation result of the arriving wave estimator 126 in FIG. The receiving device 10b controls the weight control unit 138 such that the beam is directed in the same direction as the direction of the desired reception wave.

The base station according to the fourth embodiment of the present invention includes a mobile station located in a coverage far from the base station,
Transmit the spread spectrum OFDM signal. The signal transmission speed of the spread spectrum OFDM signal is lower than that of a normal OFDM signal. That is, cell coverage is extended at the expense of signal transmission speed. Therefore, the antenna gain obtained by directing the beam of the adaptive antenna toward the mobile station has a great advantage in controlling the beam for the mobile station located at a position where a communication path is secured. That is, according to the fourth embodiment of the present invention, it is difficult to move a mobile station at a position where a communication path is secured by an antenna gain obtained by directing a beam of an adaptive antenna toward a mobile station. Acquisition of initial position information required for performing beam control of an antenna for a station is realized.

Further, once initial position information can be obtained for a mobile station located at a position where a communication path is secured by the antenna gain of the adaptive antenna, normal OFDM signal transmission becomes possible. In that case, the calculation of the weight of the adaptive antenna is based on OFDM.
This can be performed from a normal OFDM signal, not from a signal obtained by spreading the signal. That is, according to the fourth embodiment of the present invention, once a communication path is secured, it is possible to apply the conventional adaptive antenna weighting factor control method.

Referring to FIG. 12 again, in more detail, in the fourth embodiment of the present invention, first, the mobile station existing in the normal coverage includes the slots 112 and 114.
Receive a slot assignment other than When the mobile station moves from normal coverage to spread spectrum coverage, data cannot be restored from normal OFDM signals. The inverse spread spectrum circuit 142 of the receiving device 10b
A plurality of predetermined patterns are sequentially switched for all the slots of the downlink channel 106 and the uplink channel 108, and the same pattern as the pattern used by the transmitting apparatus 10a is searched, and the positions of the slots 112 and 114 are specified. I do. And the slot 112
And retrieve data from 114. However, here, actual user data communication is not performed using the spread spectrum OFDM signal as in the third embodiment of the present invention. Communication is performed using the spread spectrum OFDM signal only for detecting the position of the mobile station that has moved to the spread spectrum coverage. When the above processing is completed, the beam of the adaptive antenna is directed toward the mobile station. As a result, the required reception signal level is secured, and the slot allocation for the normal OFDM signal is performed via the random access channel 110 again. As a result, it is possible to communicate with the mobile station that has moved to the spread spectrum coverage in the same manner as the normal coverage using the normal OFDM signal. Then, the communication channel of the spread spectrum coverage is released.

According to the fourth embodiment of the present invention, the problem of the method of grasping the initial position of the mobile station (initial acquisition), which has been a problem in the system using the adaptive antenna, can be solved. Can efficiently control the weight of the adaptive array antenna,
Frequency use efficiency can be improved.

Therefore, according to the present invention, it is possible to realize a transmitting device and a receiving device capable of expanding a variable range of coverage in a dynamic cell configuration system.

Further, according to the present invention, there is provided a transmitting apparatus, a receiving apparatus, and a base station equipped with the same, which can prevent interference between adjacent cells even in a cell arrangement where available frequency resources are limited. realizable.

Further, according to the present invention, the antenna gain obtained by directing the beam of the adaptive antenna toward the mobile station is used to control the beam of the adaptive antenna for the mobile station located at a position where a communication path is secured. , A receiving device, and a base station equipped with them.

The device of the present invention can be embodied as modifications and alterations without departing from the spirit and scope of the present invention as defined by the appended claims. Therefore,
The description in the present application is for the purpose of illustration and description, and has no restrictive meaning to the present invention.

[0104]

According to the present invention, it is possible to realize a transmitting apparatus and a receiving apparatus that can extend the coverage variable range in a dynamic cell configuration system.

According to the present invention, it is possible to realize a transmitter and a receiver capable of preventing interference between adjacent cells even in a cell arrangement where available frequency resources are limited, and a base station equipped with them. .

According to the present invention, it is possible to control a beam of an adaptive antenna for a mobile station located at a position where a communication path is secured, by using an antenna gain obtained by directing a beam of the adaptive antenna toward the mobile station. , A receiving device, and a base station equipped with them.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a transmitting device and a receiving device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a cell configuration of a general cellular system.

FIG. 3 is a diagram illustrating a burst frame configuration used in the cellular system of FIG. 2;

FIG. 4 is a diagram illustrating cell coverage according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating the flow of signals in the transmitting device and the receiving device in FIG. 1 when spread spectrum and inverse spread spectrum are not performed.

FIG. 6 is a diagram illustrating the flow of signals in the transmitting device and the receiving device of FIG. 1 when performing spread spectrum and inverse spread spectrum.

FIG. 7 is a block diagram showing a configuration of a modified example of the transmitting device and the receiving device according to the second embodiment of the present invention.

FIG. 8 is a diagram illustrating the flow of signals in the transmitting device and the receiving device in FIG. 7 when spread spectrum and inverse spread spectrum are not performed.

9 is a diagram illustrating the flow of signals in the transmission device and the reception device of FIG. 7 when performing spread spectrum and inverse spread spectrum.

FIG. 10 is a diagram illustrating a general cell arrangement in a case where one frequency is used.

FIG. 11 is a diagram illustrating a cell arrangement according to a third embodiment of the present invention.

FIG. 12 is a diagram illustrating a burst frame configuration according to a third embodiment of the present invention.

FIG. 13 is a block diagram illustrating a configuration of a receiving antenna device according to a fourth embodiment of the present invention.

FIG. 14 is a block diagram showing a configuration of a transmitting antenna device according to a fourth embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 10a Transmitting device 10b Receiving device 12,36 Serial-parallel converter 14 Modulator 16 IFFT (Inverse Fast Fourier Transform) processor 18,42 Parallel-serial converter 20,140 Spreading circuit 22 Guard interval adding circuit 24 Transmission Processing circuits 26, 28 Antenna 30 Reception processing circuit 32 Guard interval removal circuit 34, 142 Despreading circuit 38 FFT (Fast Fourier Transform, Fast Fourier Transform) processor 40 Demodulator 44, 144 Pattern generator 46 Mapping setting unit 47 Demapping Setting unit 48, 62, 90, 96 Base station 50, 92 cell 52, 64, 94, 102 Mobile station 54, 104 Broadcast channel 56, 106 Downlink channel 58, 108 Uplink channel ) 60,110 random Access channel (Random acc
ess Channel) 66,98 Normal coverage 68,100 Diffusion coverage 70,72,74,76,78,80,82,84,8
6,88 Signal spectrum 112,114 Slot 116,128 Antenna element 118,130 Antenna controller 120,134 Weighter 122 Combiner 124,138 Weight controller 126 Arrival wave estimator 132 Circulator 136 Duplexer

Claims (19)

[Claims] 1. An orthogonal frequency division multiplex modulation circuit for selectively performing orthogonal frequency division multiplex modulation on an information signal to be transmitted, and a spread spectrum circuit for selectively performing spread spectrum on an output of the information signal. A transmission processing circuit for transmitting the information signal modulated by the orthogonal frequency division multiplexing modulation or the spread spectrum as a transmission signal to a reception device, wherein the reception device and the transmission device are in close proximity, When the received signal level in the case where the orthogonal frequency division multiplex modulation is performed without performing the spread spectrum and the orthogonal frequency division multiplex modulation is performed is sufficient to perform the communication between the reception apparatus and the transmission apparatus, the orthogonal frequency division multiplex modulation circuit includes: Performing the orthogonal frequency division multiplex modulation of the information signal, wherein the spread spectrum circuit does not perform spread spectrum on the information signal; When the receiving device and the transmitting device are at remote positions, the received signal level when the spread spectrum is not performed and the orthogonal frequency division multiplex modulation is performed, the communication between the receiving device and the transmitting device is performed. When the frequency is insufficient, the orthogonal frequency division multiplex modulation circuit does not perform the orthogonal frequency division multiplex modulation, and the spread spectrum circuit performs spectrum spreading of the output of the orthogonal frequency division multiplex modulation circuit. A transmitting device that uses orthogonal frequency division multiplexing modulation and spread spectrum in combination. 2. The information signal is provided as a serial signal. The orthogonal frequency division multiplexing / modulating circuit includes a serial / parallel converter for converting the information signal from serial to parallel, and a frequency converter for converting the parallel converted information signal to frequency. A modulator that maps to the symbols of the region, an inverse fast Fourier transformer that performs an inverse fast Fourier transform of the mapped information signal, and a parallel-serial converter that converts the inverse fast Fourier transformed information signal from parallel to serial. 2. The transmitting apparatus according to claim 1, wherein the transmitting apparatus uses the orthogonal frequency division multiplexing modulation and the spread spectrum. 3. The spread spectrum circuit according to claim 1, further comprising a spread spectrum signal generation circuit for generating a plurality of spread spectrum signals.
A transmission device that uses orthogonal frequency division multiplexing modulation and spectrum spreading described in 1 above. 4. The transmission processing circuit includes an adaptive array antenna, wherein the receiving device and the transmitting device are located at remote positions, and a gain by the orthogonal frequency division multiplex modulation makes communication between the receiving device and the transmitting device. If it is insufficient to perform, the direction of the receiving apparatus with respect to the transmitting apparatus is detected by the transmission signal output from the spread spectrum circuit and subjected to the spread spectrum, and the beam of the adaptive array antenna is moved. 4. The reception signal level of the receiving device is increased by directing the receiving device toward a station, and communication between the receiving device and the transmitting device by the orthogonal frequency division multiplex modulation is enabled. A transmitting apparatus that uses both the described orthogonal frequency division multiplexing modulation and spread spectrum. 5. An orthogonal frequency division multiplex modulation circuit for performing a first orthogonal frequency division multiplex modulation on an information signal to be transmitted, and selectively performing spread spectrum on an output of the orthogonal frequency division multiplex modulation circuit. A spread spectrum circuit, and a transmission processing circuit for transmitting an output of the spread spectrum circuit as a transmission signal to a receiving device, wherein the receiving device and the transmitting device are in close proximity, do not perform the spread spectrum, and When the received signal level when the first orthogonal frequency division multiplex modulation is performed is sufficient to perform communication between the reception device and the transmission device, the orthogonal frequency division multiplex modulation circuit performs the first orthogonal frequency division multiplex modulation. Performs orthogonal frequency division multiplexing modulation, the spread spectrum circuit does not perform spectrum spreading of the output of the orthogonal frequency division multiplexing modulation circuit, The transmitting apparatus is located at a remote position, and the received signal level in the case where the spread spectrum is not performed and the first orthogonal frequency division multiplex modulation is performed is required for performing communication between the receiving apparatus and the transmitting apparatus. When there is a shortage, the orthogonal frequency division multiplex modulation circuit performs a second orthogonal frequency division multiplex modulation having a bandwidth narrower than the bandwidth of the first orthogonal frequency division multiplex modulation, A transmitting apparatus using orthogonal frequency division multiplexing modulation and spectrum spreading, wherein the circuit spreads the spectrum of the output of the orthogonal frequency division multiplexing modulation circuit. 6. The orthogonal frequency division multiplex modulation circuit also performs phase modulation of the information signal.
A transmission device that uses orthogonal frequency division multiplexing modulation and spectrum spreading described in 1 above. 7. A mapping circuit for mapping an information signal to be transmitted for the first orthogonal frequency division multiplexing modulation to a symbol in a frequency domain, and selectively performing spread spectrum on an output signal from the mapping circuit. A spread spectrum circuit to perform, an orthogonal frequency division multiplex modulation circuit that performs the first orthogonal frequency division multiplex modulation on an output signal from the spectrum spread circuit, and an output of the orthogonal frequency division multiplex modulation circuit as a transmission signal. And a transmission processing circuit for transmitting to the receiving device. The receiving device when the receiving device and the transmitting device are in close proximity, does not perform the spread spectrum, and performs the first orthogonal frequency division multiplex modulation. When the signal level is sufficient to allow communication between the receiving device and the transmitting device, the orthogonal frequency division multiplexing modulation circuit Performing a first orthogonal frequency division multiplexing modulation, the spread spectrum circuit does not perform spread spectrum on the output signal from the mapping circuit, the receiving device and the transmitting device are at remote locations, the spread spectrum is not performed, and When the received signal level when the first orthogonal frequency division multiplex modulation is performed is insufficient for performing communication between the reception device and the transmission device, the orthogonal frequency division multiplex modulation circuit includes the A second orthogonal frequency division multiplexing modulation having a bandwidth narrower than that of the first orthogonal frequency division multiplexing modulation, and the spread spectrum circuit spreads the spectrum of an output signal from the mapping circuit. A transmission device using both orthogonal frequency division multiplexing modulation and spread spectrum. 8. The transmission processing circuit includes an adaptive array antenna, wherein the reception device and the transmission device are located at remote positions, and a gain by the orthogonal frequency division multiplexing modulation is used for communication between the reception device and the transmission device. If it is insufficient to perform, the direction of the receiving apparatus with respect to the transmitting apparatus is detected by the transmission signal output from the spread spectrum circuit and subjected to the spread spectrum, and the beam of the adaptive array antenna is moved. 8. The reception signal level of the receiving device is increased by directing the receiving device toward a station, and communication between the receiving device and the transmitting device by the first orthogonal frequency division multiplex modulation is enabled. A transmission device that uses orthogonal frequency division multiplexing modulation and spectrum spreading described in 1 above. 9. An inverse spread spectrum circuit for selectively despreading an information signal transmitted from a transmitting device and received by the receiving device in a frequency domain, and an orthogonal frequency division multiplex demodulation for the information signal. An orthogonal frequency division multiplexing demodulation circuit that performs the following, where the receiving device and the transmitting device are in close proximity, the received signal level when the despreading is not performed and the orthogonal frequency division multiplexing demodulation is performed, When sufficient to perform communication between the receiving device and the transmitting device, the despreading circuit does not despread the received information signal,
And the orthogonal frequency division multiplex demodulation circuit performs the orthogonal frequency division multiplex demodulation of the received information signal, the receiving apparatus and the transmitting apparatus are located at remote positions, the despreading is not performed, and the orthogonal frequency division is performed. When the gain due to multiplex demodulation is insufficient to perform communication between the receiving device and the transmitting device, the despread spectrum circuit despreads the received information signal, and the orthogonal frequency division multiplex demodulation circuit A receiving apparatus that uses both orthogonal frequency division multiplexing modulation and spread spectrum without performing the orthogonal frequency division multiplexing demodulation of the received information signal. 10. The orthogonal frequency division multiplex demodulation circuit,
10. The receiving apparatus according to claim 9, wherein the information signal is also phase-demodulated. 11. An orthogonal frequency division multiplex demodulation circuit for performing a first orthogonal frequency division multiplex demodulation on an information signal transmitted from a transmission device and received by the reception device, and an output of the orthogonal frequency division multiplex demodulation circuit. An inverse spread spectrum circuit for selectively performing despreading in the frequency domain, and a demapping circuit for demapping the despread signal in the frequency domain for the first orthogonal frequency division multiplex demodulation, When the receiving apparatus and the transmitting apparatus are in close proximity, the despreading is not performed, and the first orthogonal frequency division multiplexing demodulation is performed in a first bandwidth, the received signal level is increased by the receiving apparatus. And when it is sufficient to communicate with the transmitting device, the orthogonal frequency division multiplex demodulation circuit performs the first orthogonal frequency division multiplex demodulation of a received information signal, and performs the inverse The spread spectrum circuit does not perform despreading of the received information signal, the receiving device and the transmitting device are located at remote positions, the despreading is not performed, and the first orthogonal frequency division multiplex demodulation is performed. When the received signal level in the case is insufficient to perform communication between the receiving device and the transmitting device, the orthogonal frequency division multiplex demodulation circuit is configured to have a bandwidth higher than the bandwidth of the first orthogonal frequency division multiplex demodulation. Orthogonal frequency division multiplex demodulation and despreading, wherein the second orthogonal frequency division multiplex demodulation having a narrow bandwidth is performed, and the despread spectrum circuit despreads the output of the orthogonal frequency division multiplex demodulation circuit. Receiving device used together. 12. An orthogonal frequency division multiplex demodulation circuit for performing orthogonal frequency division multiplex demodulation on an information signal transmitted from a transmitting device and received by the receiving device, and selectively despreading the received information signal. And a demapping circuit for selectively demapping the orthogonal frequency division multiplexed demodulated signal in the frequency domain, wherein the receiving device and the transmitting device are in close proximity and the despreading is performed. And when the received signal level when the orthogonal frequency division multiplex demodulation is performed is sufficient to perform communication between the receiving apparatus and the transmitting apparatus, the orthogonal frequency division multiplex demodulation circuit performs Perform the orthogonal frequency division multiplex demodulation of the information signal, and the despread spectrum circuit does not perform despreading of the output of the orthogonal frequency division multiplex demodulation circuit, When the receiving device and the transmitting device are at remote positions, and the despreading is not performed and the orthogonal frequency division multiplex demodulation is performed, the received signal level performs communication between the receiving device and the transmitting device. Wherein the orthogonal frequency division multiplex demodulation circuit does not perform the orthogonal frequency division multiplex demodulation and the despread spectrum circuit despreads the received information signal. A receiver that uses both multiplex modulation and spread spectrum. 13. The orthogonal frequency division multiplex modulation and spectrum spreading according to claim 12, wherein said inverse spread spectrum circuit is provided with a spread spectrum signal generating circuit for generating a plurality of spread spectrum signals. Receiving device used together. 14. The orthogonal frequency division multiplex demodulation circuit,
A serial-parallel converter for converting the information signal from serial to parallel;
14. The receiving apparatus according to claim 12, further comprising at least a fast Fourier transformer for fast Fourier transforming the parallel-converted information signal. 15. The orthogonal spread-spectrum multiplex modulation and spread spectrum according to claim 12, wherein the inverse spread spectrum circuit changes a spread spectrum signal to be generated for each transmission apparatus. Receiver. 16. A first transmission mode for transmitting a signal having a first transmission rate and a first gain, a second transmission rate lower than the first transmission rate, and a second transmission rate lower than the first gain. A transmission device having a second transmission mode for transmitting a signal having a large second gain; and a first device for receiving a signal transmitted in the first transmission mode.
And a second reception mode for receiving a signal transmitted in the second transmission mode, wherein the mobile station and the base station are in close proximity, and the first
When communication is maintained by the transmission mode and the first reception mode, the base station performs communication by the first transmission mode and the first reception mode, and the mobile station and the base station Are at a remote location and the first
The base station performs communication in the second transmission mode and the second reception mode when communication cannot be maintained in the transmission mode and the first reception mode. 17. The second transmission mode and the second reception mode in an area belonging to both an area served by the base station and an area served by another adjacent base station having the same configuration. The base station according to claim 16, wherein communication is performed by: 18. The first transmission mode and the first reception mode of the base station are the first transmission mode and the first reception mode of another adjacent base station having the same configuration. Using the same communication resources as the above, the second transmission mode and the second reception mode of the base station, and the second transmission mode and the second transmission mode of another adjacent base station having the same configuration. 18. The base station according to claim 17, wherein a communication resource different from the second reception mode is used. 19. The transmitting apparatus includes an adaptive array antenna, wherein the base station and the mobile station are at remote positions, and wherein gains in the first transmission mode and the first reception mode are different from those of the base station and the mobile station. When there is insufficient communication with the mobile station, the base station and the mobile station communicate with each other by the second transmission mode and the second reception mode, and the mobile station communicates with the base station. Detect the direction,
The transmission power to the mobile station is increased by the adaptive array antenna, and the first transmission mode and the first
19. The base station according to claim 18, wherein the base station and the mobile station perform communication in the first transmission mode and the first reception mode after the gain of the first reception mode is improved. Bureau.