JPH08130524A - Radio communication line control system - Google Patents

Abstract

PURPOSE: To attain high transmission efficiency by continuously changing the transmission frequency of a single frequency signal on a time axis in a request signal transmitting section, diffusing the frequency on a frequency axis and reversely diffusing the difused frequency in a master station. CONSTITUTION: In a transmitter for a compact earth station, a line control circuit 39 always recognizes the transmission timing of a single frequency signal and an information data signal 42 from frame timing 38 and accurately control switching between a single frequency signal generator 31 and a data signal control circuit 43. A request signal generated from the generator 31 is continuously phase-shifted on the time axis by a phase shifter 33, the spectrum of the single frequency signal is continuously changed on the frequency axis and turned to a frequency-diffused signal equivalently diffusing its band width in a request section and the frequency diffused signal is multiplied by a high frequency signal to send the multiplied signal. On the other hand, a central earth station applies frequency conversion reversible to that executed at the time of transmitting a request signal to a received synthetic signal to execute reverse diffusion processing.

Description

Detailed Description of the Invention

[0001]

The present invention is applicable to all wireless communication systems such as digital fixed wireless communication systems, digital mobile wireless communication systems, digital fixed satellite communication systems and digital mobile satellite communication systems. Regarding control.

[0002]

2. Description of the Related Art As one of fixed satellite communication systems using a small earth station which is currently commercialized, VSAT (V
ery Small Aperture Termin
al) system. For operation of the VSAT system, a slotted aloha (S-ALOHA) system and a demand assign type multiple request (DAMA) system are mainly used as request control procedures. The S-ALOHA method is a method in which all users exchange communication by randomly transmitting communication packets to the central earth station based on the determined slot timing, and data such as card verification and POS data transmission. It is effective for short and long communication.

On the other hand, in the DAMA system, a communication channel request signal (request signal) is first transmitted from the VSAT station on the ground to the central earth station, and the central earth station determines the communication information amount based on the communication information amount notified by the request signal. VSAT
The number of TDMA slots required for information transmission is assigned to the station. ACK sent from the central earth station at the VSAT station
The information signal is transmitted at the designated communication slot timing based on the communication channel allocation information included in the signal.

As described above, in the DAMA method, once a communication channel is assigned, collision with a packet signal transmitted from another VSAT station is eliminated, so that high quality and stable communication can be performed.

However, in the DAMA method, S-AL is used.
Unlike the OHA system, it is necessary to always transmit a request signal to acquire the communication channel allocation information from the central earth station, so that a transmission delay of 2 hops occurs before information transmission is started. Therefore, it is not suitable for information transmission in which the amount of information to be transmitted is short, such as about 1 slot.
It is possible to realize higher throughput for communication with a relatively large amount of data such as batch processing.

[0006]

When the S-ALOHA method described above is applied as the request control procedure, a collision of request packet signals, which means a request for allocation of a communication channel, when the traffic amount, that is, the communication request frequency, increases. Occurs frequently, the transmission delay becomes extremely large, and the throughput decreases.

On the other hand, even in the demand assign system, when the first channel allocation request signal is transmitted, another V
There is a problem of collision with the request packet signal of the SAT station, and when the traffic amount increases, the packet signal frequently collides when transmitting the request signal, resulting in a problem that the transmission delay amount becomes extremely large. In particular, in a system for a large number of VSAT stations, it is extremely difficult to provide an efficient communication service to users by these conventional techniques, and some new request control procedure must be developed.

In order to solve the above problems, Japanese Patent Application No. 5-
In "Wireless communication line control method" of 325768, a single frequency signal having a different frequency and transmission timing for each small earth station is given in advance as a request signal to mean a request for allocation of communication channels to the central earth station. A line control method has been proposed in which multiple request signals can be sent simultaneously from a plurality of small earth stations. here,
The central earth station receives a composite signal composed of multiple single frequency signals, and separates the received signals for each frequency of each single frequency signal. It is possible to always recognize whether the request signal has been transmitted from.

By this method, it is possible to solve the problem of packet collision at the time of transmitting a request signal.

However, since a plurality of single-frequency signals are simultaneously transmitted from each small earth station and are input / amplified as a composite signal to the satellite relay amplifier having nonlinear characteristics, the satellite output signal depends on the amplifier. Non-linear distortion occurs, which makes it extremely difficult for the receiver of the central earth station to accurately separate and recognize a plurality of single-frequency signals.

Further, the radio waves radiated from the transmitter of the small earth station may be superposed with an unnecessary wave having a bright line spectrum from the transceiver circuit or other system in addition to the carrier wave used for the original communication. Although the emission of such an unnecessary wave is called a spurious, it is very difficult to distinguish its emission line spectrum from a single frequency signal for request. In other words, the probability of erroneously detecting a spurious signal as a single frequency signal or the possibility of non-detection of a request single frequency signal due to interference of spurious signals increases, so the recognition probability of the presence or absence of a request signal deteriorates. The problem arises.

The present invention solves the drawbacks of the prior art in which such a single frequency signal is used as a request signal, is less susceptible to the effects of the satellite's nonlinear amplifier, and the effects of spurious signals from the transceiver or other systems, and The present invention provides a wireless communication line control system that enables efficient transmission of request signals.

[0013]

In order to achieve this object, the wireless communication line control system according to the present invention uses a single frequency signal having different frequency and transmission timing as a request signal for each small earth station in advance. , The transmission frequency of the single frequency signal assigned to the small earth station is continuously changed on the time axis in the request signal transmission section, and spreads to a certain bandwidth on the frequency axis. The small earth station sends a request signal to the central earth station to request the allocation of communication channels at the same time, and in the central earth station, a composite signal composed of a plurality of single frequency signals that continuously change on the frequency axis. Received
The receiving device of the central earth station continuously performs frequency conversion on the time axis, which has a reversible relationship with the time of transmitting the request signal, on the received combined signal, and performs despreading operation to perform reception combining. The signal is separated for each frequency of the single frequency signal for each small earth station, and it is always recognized from the frequency of the single frequency signal and the transmission timing, from which small earth station the request signal was transmitted, and the information is By using the downlink to transmit the communication channel allocation information to the group of small earth stations that request the communication channel allocation from the central earth station, the nonlinearity of the satellite repeater and the transmission of the small earth station The structure is characterized in that the influence of spurious signals generated from the machine is removed.

Furthermore, in the technique of continuously changing the transmission frequency of the request single frequency signal in the request signal transmission section on the time axis and applying the frequency spreading to a constant bandwidth on the frequency axis, Of multiple request signals at the same time by assigning the same single frequency signals of different slave stations to different slave stations at the same time and changing them positively and negatively on the frequency axis at different rates of change on the time axis. The signal spreads in different positive and negative directions centering on the carrier frequency of the signal, while the receiving device of the master station requests the spread combined signal of the spread single frequency signals of the same frequency. Frequency conversion, which has a reversible relationship with the time of signal transmission on the time axis, is performed in parallel for all types of spreading factors, and the despreading operation is performed to re-read from multiple slave stations. The presence or absence of Est is recognizable and makes a time has a construction which is characterized in that to allow the identification of the request signals from a plurality of small earth stations different by a single frequency signal of the same frequency.

[0015]

Thus, a single frequency signal having different frequencies is used as a request signal for requesting communication channel allocation, continuously changed on the time axis over the request signal transmission section, and spread on the frequency axis. This enables a plurality of small earth stations to simultaneously transmit request signals to the central earth station. That is, the conventional S
It is possible to solve the problem of packet collision that occurs when a request packet signal of the ALOHA method or the DAMA method is transmitted, and it is possible to achieve high transmission efficiency.

Furthermore, when a composite signal composed of a plurality of single frequency signals is input to the non-linear amplifier of the satellite, an intermodulation wave between the single frequency signals of different frequencies is generated due to the non-linear characteristics of the amplifier, and the single frequency signal It was extremely difficult to accurately separate and recognize multiple single-frequency signals in the receiver of the central earth station because the spectrum is generated at a frequency different from the transmission frequency. By making the spread signal small and less susceptible to the influence of the non-linear amplifier, it is possible to suppress the generation of intermodulation waves at the output of the satellite repeater, and to easily separate and recognize the request signal at the receiver of the central earth station. . Furthermore, for spurious signals generated from transceivers or other systems of small earth stations,
By performing the despreading operation at the receiver of the central earth station, the spectrum of the spurious signal is spread, and the effect on the requesting single frequency signal can be removed. As described above, by applying the method of the present invention to the line control procedure of the wireless communication system, the erroneous detection / non-detection of the request signal, which is a problem in the conventional line control system using the single frequency signal as the request signal, is increased. It is possible to solve the problem of.

[0017]

FIG. 1 shows an embodiment of a system configuration diagram of the system of the present invention. In the figure, the total number of L stations (L = 2m + 1: m
Is a natural number) to each small earth station 3 in advance with frequencies f _{1 to} f
_When a request for a single frequency signal of _L and slot number M is assigned, and a request for communication is made from a small earth station, the single frequency signal for request is used to transmit to the central earth via the communication satellite 1. A request for allocation of a communication channel is made to the station 2. At this time, the modulator included in each small earth station continuously changes the single frequency signal transmitted by the own station on the time axis in the request signal transmission section based on the following calculation formula. f _k = P × cos [(ω _C + 2π {k− (L + 1) /
2} Δf) t + at ² + θ _k ] where, f _k is the request frequency spread signal of the k-th small earth station, P is the transmission voltage level of the request signal, and f is the request signal.
_C = ω _C / 2π is the center frequency of the carrier wave, Δf is the frequency interval of the single frequency signal, a is the phase shift coefficient when the single frequency signal is continuously changed on the time axis, and θ _k is the k-th Each represents the initial phase of a request single frequency signal of a small earth station.

At this time, carrier frequencies f _{1 to} f _L of all request single frequency signals 4-1 to 4- _L are as shown in FIG.
Because they are continuously changing the frequency on the time axis as shown in (a), the frequency spread signal spread in bandwidth 2AT _a on the frequency axis as shown in FIG. 2 (b) 5-1~5-L
Sent as. However, T _a represents the request signal section length 11. Here, since the request frequency spread signals 5-1 to 5-L are simultaneously transmitted from a plurality of small earth stations, they are input and amplified as the spread spectrum combined signal 6 in the satellite repeater, and as a result, At the receiver of the central earth station, the spread spectrum composite signal 6 is received as a multiplex amplified signal by a plurality of request spread spectrum signals. Next, the receiver of the central earth station performs frequency conversion on the received spread spectrum combined signal based on the following conversion formula, which has a reversible relationship with the time of transmission. First,
When the spread spectrum combined signal received as the high frequency signal is converted into the base band signal, the spread spectrum combined base band signal f _b is

[0019]

[Equation 1]

Is expressed as However, in reality, the reception voltage level is different from that at the time of transmission due to the amplifier included in the satellite repeater, the attenuation due to propagation, and the like, so the reception voltage level is newly expressed as A. Next, frequency conversion, which has a reversible relationship with the time of transmission, is performed on the spread spectrum combined baseband signal based on the following conversion formula.

[0021]

[Equation 2]

By the above despreading operation, the request spread spectrum composite signal 6 spread in frequency passes through the receiver output signals 7-1 to 7-L at time t shown in FIG. The single frequency reception signals 8-1 to 8-L assigned to each small earth station shown in FIG. 2 (d) can be converted back into the combined reception signal 9. Here, each small earth station 3
Single frequency signals transmitted from different frequencies f _{1 to} f
_{Since L} is allocated, even if a plurality of small earth stations 3 simultaneously send request signals to the central earth station 2, the receiver of the central earth station 2 combines the single frequency signals into each frequency signal. Each can be separated.
Based on the output of this receiver, the communication channel allocation to the specific small earth station requesting the communication channel allocation is performed by the line control device of the central earth station 2, and the communication of the small earth station 3 to be communicated is performed. Communication channel information including an identification number (ID number) and an assigned slot number is broadcast on the downlink. Here, in the small earth station 3,
Always receive the downlink signal from the Central Earth Station 2,
Detects only information signals that include your own ID signal,
The transmission timing is recognized from the communication slot number assigned to the own station, and the transmission of the information signal from the small earth station is started.

FIG. 3 shows an embodiment of the signal frame format and request signal spectrum when the method of the present invention is specifically applied to the TDMA method. In the figure, T _f is the frame length (frame period) of one TDMA frame 12, T _s is the slot length of the TDMA slot 13, Δf is the frequency interval 16 of the single frequency signal before spreading,
, F ₁ , f ₂ , ..., F _L respectively represent the pre-spread single frequency signals 14 pre-applied to each small earth station. A request signal transmission section 11 is set in the first slot of the TDMA frame, and request signals are transmitted from each small earth station in this section.
On the other hand, each single frequency signal 14 can be separated by a receiver included in the central earth station 2.

Here, each small earth station 3 is previously assigned a slot number for request and a single frequency signal frequency, and the small earth station 3 sends its own station when there is a request for communication. The assigned single frequency signal is transmitted while continuously changing the frequency on the time axis during the request period (FIG. 2A). As a result, the spectrum of the single frequency signal transmitted in the request signal section is shown in FIG.
Spread signal 5 with bandwidth 2aT _a as shown in (b)
-1 to 5-L. On the contrary, the receiver of the central earth station performs despreading operation on the received spread spectrum combined baseband signal, so that it is assigned to each small earth station as shown in FIG. 2 (d). Multiple single frequency signals can be generated separately.

Next, FIGS. 4 and 5 show an embodiment of the single frequency spreading / despreading request system according to the present invention. In the embodiments up to the preceding paragraph, an independent single frequency signal is assigned as a request signal to each small earth station, but by using the following method, a single frequency signal of a certain frequency is assigned to a plurality of small earth stations. It is possible to assign to stations at the same time. That is, as shown in FIG. 4, a plurality of single frequency signals having the same frequency are centered on the carrier frequency, and a plurality of phase shift coefficients a _{1 to} a _J (20-1 to 20) different in the positive and negative directions on the frequency axis. varying in on the time axis -J), each single-frequency signal bandwidths 2a ₁ different on the frequency axis as shown in FIG. 5 T _a ~2a _J T _a
(21-1 to 21-J). This request frequency spread signal is expressed by a calculation formula: f _{k, i} = P × cos [(ω _C + 2π {k− (L + 1) /
2} Δf) t + a _i t ² + θ _k ]. Here, f _{k, i} is a request spread spectrum signal of the i-th small earth station among the small earth stations of the J station grouped by using the k-th single frequency signal, and a _i is grouped The phase shift coefficient used when the request single frequency signal of the i-th small earth station among the small earth stations of J station is continuously changed on the time axis is shown.
Since the request frequency spread signal f _{k, i} is simultaneously transmitted from a large number of small earth stations, it is input and amplified by the satellite repeater as a spread spectrum combined signal, and as a result, the central earth station has it. The receiver receives the signal as a multiple amplified signal of a spread spectrum synthesized signal by a large number of request spread spectrum signals.

Next, the receiver of the central earth station performs frequency conversion on the received spread spectrum combined signal based on the following conversion formula, which has a reversible relationship with the time of transmission. First, when the spread spectrum combined signal received as the high frequency signal is converted into the base band signal, the spread spectrum combined base band signal f _b is obtained.

[0027]

(Equation 3)

Is represented as However, in reality, the reception voltage level is different from that at the time of transmission due to the amplifier included in the satellite repeater, the attenuation due to propagation, and the like, so the reception voltage level is newly expressed as A. Next, frequency conversion, which has a reversible relationship with the time of transmission, is performed on the spread spectrum combined baseband signal based on the following conversion formula.

[0029]

[Equation 4]

By the above despreading operation, the phase shift coefficient a on the time axis among the small earth stations (L × J)
i th all small earth station is frequency spread with _i (L
The request frequency-spreading combined signal assigned to the station) can be reconverted into a combined signal of L single-frequency signals assigned to the i-th small earth station. Here, since the single frequency signals transmitted from the respective small earth stations 3 are assigned different frequencies, even if the small earth stations 3 of the L stations simultaneously transmit request signals to the central earth station 2, The receiver of the central earth station 2 can separate the composite signal of the single frequency signals for each frequency. By performing the above operation for all a _i of i = 1 to J, the presence / absence of a request from the small earth station of the L × J station can be finally recognized at one time.

Next, specific circuit configurations of the transmitter of the small earth station and the receiver of the central earth station are shown in FIGS. 6 and 7, respectively. However, an embodiment intended for a line control method using a plurality of phase shift coefficients will be shown.

In FIG. 6, the line control circuit 39 constantly recognizes the transmission timing of the single frequency signal and the information data signal 42 from the frame timing 38 separately detected by the receiver of the small earth station. Switching control between the one-frequency signal generator 31 and the data signal control circuit 43 can be accurately performed. Here, the request single frequency signal 32 generated from the single frequency signal generator 32 is continuously + a _i t ² (0 <t <T _S ) on the time axis by the phase shifter 33. A phase shift is added. By this phase shifter, the spectrum of the single frequency signal continuously changes on the frequency axis, and becomes a frequency spread signal in which the bandwidth is equivalently spread in the request section. This frequency spread signal 34 is multiplied by a high frequency signal 49 from a high frequency oscillator 48 by a multiplier 35,
A request signal is sent from the transmitting antenna 37 to the central earth station as a high frequency spread signal 36.

On the other hand, in the slot section for data transmission,
The information data signal 44 whose timing is controlled by the data signal control circuit 43 is input to the modulation circuit 45, and its output signal 46 is multiplied by the high frequency signal 50 from the high frequency oscillator 48 by the multiplier 47 and transmitted as the high frequency modulation signal 51. An information data signal is transmitted from the antenna 37 to the central earth station.

On the other hand, in the central earth station, the high frequency signal from the small earth station received by the antenna 61 is frequency-converted by the frequency converter 63 and then converted into a baseband signal by the low pass filter 65. Since the central earth station always recognizes the frame timing and the slot timing 67, the switch 66 can accurately switch the request signal section and the information data signal section. That is, in the request signal reception section, the switch 66 is connected to the request single frequency signal reception circuit 60, while in the information data signal reception section it is connected to the demodulation circuit 83. The request single frequency signal receiving circuit 60 includes a plurality of phase shifters (71
-1 to J), a discrete Fourier transformer (72-1 to J), and a single frequency signal detector (73-1 to J), and each phase shifter is the same as that used on the small earth station side. phase shift coefficients a _1, a _2, ..., the phase shift factor -a ₁ a relationship of a _J and reversible, -a _2, ..., has a -a _J.
Here, by branching and inputting the frequency spread composite signal for request transmitted from the group of small earth stations to each phase shifter, the small earth station corresponding to each phase shift coefficient of the frequency spread composite signal shown in FIG. It is possible to separate the received signal consisting of a plurality of single frequency signals for each group of groups. Next, the outputs of the phase shifters (71-1 to J) are frequency-separated for each single frequency signal by the discrete Fourier transformers (72-1 to J), and the single frequency detector (73- 1 to J), it is possible to instantly recognize which small earth station has transmitted the request signal.
The outputs of the single frequency signal detectors (74-1 to J) are input to the line controller 70, and communication channels are assigned to the respective small earth stations that have made a communication request. To the small earth station group using the downlink.

On the other hand, in the information data signal reception slot section, the switch 66 is connected to the line 69, and the demodulation circuit 78 uses the channel assignment information 76 from the line control device 70 to obtain the information data for each small earth station. Signal 7
7 can be demodulated and detected.

Although the embodiments have been described above by taking the fixed satellite communication system as an example, the method of the present invention is also applicable to the mobile satellite communication system, and the configuration is such that a small earth station moves on the ground. The realization method can be easily inferred from the above-described embodiment. Further, in the above embodiment, the present invention is applied to the land mobile communication system by replacing the small earth station with the mobile terminal of the land mobile communication system and the central earth station with the base station or the line control station of the land mobile communication system. It can also be used as a line control procedure and can be applied to any wireless communication system such as a land-based communication system using a fixed wireless terminal. Furthermore, although the TDMA method is assumed as the access control method in this embodiment, the FDM
The present invention can be applied as a line access control procedure of any type of wireless communication system such as A, CDMA system and normal SCPC system. It should be noted that this patent focuses on the line control procedure in the satellite communication system, and various types of transceivers can be envisioned for the small earth station and the central earth station. Furthermore, in the present embodiment, when a single frequency signal is continuously changed on the time axis, a coefficient that changes linearly with time on the frequency axis is assumed, but the frequency change rate is also wavelet function. , Any kind of rate of change such as trigonometric functions can also be used.

[0037]

【The invention's effect】

(1) By using single-frequency signals of different frequencies as request signals, it becomes possible for a plurality of small earth stations to simultaneously transmit request signals to the central earth station, and the conventional S-ALOHA method and DAMA method can be used. It is possible to solve the problem of packet collision at the time of transmitting a request signal, and to greatly improve the transmission delay characteristic that is greatly deteriorated as the traffic amount increases.

(2) Since the retry due to collision of request packet signals is eliminated, if the number of small earth stations is equal to or less than the number of request signals that can be assigned in advance, the transmission delay characteristic does not deteriorate even if the traffic amount increases. Communication channels can be assigned.

(3) The influence of the intermodulation wave generated by the non-linear characteristic of the satellite relay amplifier can be suppressed, and the request signal can be easily separated and recognized in the receiver of the central earth station.

(4) The spectrum of the spurious signal is obtained by despreading the impulse-shaped spurious signal generated by the transmitter of the small earth station on the frequency axis by the receiver of the central earth station. It can be spread to remove the effect on the single frequency signal for the request.

(5) It is possible to solve the problem of increase in erroneous detection / non-detection of a request signal, which has been a problem in the conventional line control system using a single frequency signal as a request signal.

[Brief description of drawings]

FIG. 1 is a diagram showing a system configuration concept of a satellite communication system according to the present invention.

FIG. 2 is a diagram showing an embodiment of a request system using a spread spectrum signal of a single frequency signal according to the present invention.

FIG. 3 is a TDMA applied to a satellite communication system according to the present invention.
It is a figure which shows the Example of a frame format.

FIG. 4 is a diagram showing an embodiment of a single frequency spreading / despreading request system according to the present invention.

FIG. 5 is a diagram showing spectrum characteristics of a single frequency spreading / despreading request system according to the present invention.

FIG. 6 is a diagram showing an example of a circuit configuration of a transmitter included in a slave station according to the present invention.

FIG. 7 is a diagram showing an example of a circuit configuration of a receiver included in a master station according to the present invention.

[Explanation of symbols]

 1 Communication Satellite 2 Central Earth Station 3-1 to L Small Earth Station 4-1 to L Single Frequency Signal for Request 5-1 to L Frequency Spread Signal for Request 6 Frequency Spread Composite Signal 7-1 to L Receiver Output Signal 8-1 to L Single frequency reception signal 9 Single frequency synthesis reception signal 10 Data signal transmission section 11 Request signal transmission section 12 TDMA frame 13 TDMA slot 14 Single frequency signal for request 16 Frequency interval of single frequency signal 20- 1 to J Phase shift change rate 21-1 to J Frequency spread bandwidth 31 Single frequency signal generator 32 Single frequency signal 33 Phase shifter 34 Frequency spread signal 35 Multiplier 36 High frequency spread signal 37 Small earth station antenna 38 Frame Timing 39 Line control circuit 40, 41 Line control signal 42 Information data signal 43 Data Control circuit 44 Information data signal 45 Modulation circuit 46 Modulation signal 47 Multiplier 48 High frequency oscillator 49, 50 High frequency signal 51 High frequency modulation signal 60 Single frequency signal receiving circuit for request 61 Central earth station antenna 62 Multiplier 63 Frequency converter 64 Low frequency signal 65 Low pass filter 66 Changeover switch 67 Frame timing / Slot timing 68, 69 Line 70 Line control circuit 71-1 to J Phase shifter 72-1 to J Discrete Fourier transformer 73-1 to J Single frequency Detector 74-1 to J Single frequency signal detector output 75 Line control signal 76 Channel allocation information 77 Information data signal 78 Demodulation circuit 79 Transmission circuit input line

Claims (2)

[Claims] 1. A wireless communication system comprising a plurality of slave stations and a master station that performs wireless communication between the slave stations and performs line control of all slave stations, wherein A single frequency signal whose frequency and transmission timing are different for each slave station is given in advance to each slave station as a request signal, and the frequency of the single frequency signal is repeatedly generated. Then, by spreading to a certain bandwidth on the frequency axis, multiple slave stations simultaneously send request signals for requesting communication channel allocation to the master station, and the master station transmits on the frequency axis on the frequency axis. The receiving device of the master station receives a composite signal composed of a plurality of continuously changing single frequency signals, and the receiving device of the master station has a reversible relationship with the request signal transmission. By performing frequency conversion continuously on the time axis and performing despreading operation, the received combined signal is separated for each frequency of the single frequency signal for each slave station, and the frequency of the single frequency signal is From the transmission timing, it is possible to recognize from which slave station the request signal is transmitted, and by using this information, the master station transmits the communication channel allocation information to the slave station group requesting the communication channel allocation. A wireless communication line control method, wherein transmission is performed using a downlink from a master station to the slave station group. 2. The wireless communication line control system according to claim 1, wherein the transmission frequency of the request single frequency signal is changed on the time axis in the request signal transmission section, and a constant bandwidth is on the frequency axis. In the method of performing frequency spreading on, the same single frequency signal is simultaneously assigned to a plurality of different slave stations, and the plurality of single frequency signals of the same frequency are changed in positive and negative directions on the frequency axis on different time axes. By continuously varying the respective request signals with different spreading factors in the positive and negative directions with the carrier frequency of the single frequency signal as the center, the receiving device of the master station spreads the request signals. With respect to the spread and synthesized signal of the plurality of single frequency signals of the same frequency, there is a reversible relationship on the time axis with the frequency conversion applied to the plurality of single frequency signals at the time of transmitting the request signal. By performing frequency conversion in parallel for all types of spreading factors and executing despreading operations, the presence or absence of requests from multiple slave stations can be recognized at one time, and different multiple signals with a single frequency signal of the same frequency can be recognized. Single-spreading / despreading line control method that enables simultaneous requests from other slave stations