JP2545787B2 - Multidirectional wireless communication system - Google Patents

Description

The present invention relates to a multi-directional multiplex wireless communication system, and more particularly to time division multiplex / time division multiple access (TDM-TDMA) between a base station and a plurality of subscriber stations. The present invention relates to a multi-directional multiplex wireless communication system for performing high-speed digital communication by the () system.

[Conventional technology]

In the multi-directional multiplex wireless communication system based on the TDM-TDMA system, communication from a base station to each subscriber station is performed by designating a specific time slot by the TDM system. On the other hand, communication from each subscriber station to the base station is performed by the TDMA method, and each subscriber station uses the timing reference signal transmitted from each base station as a reference so that it does not overlap with the radio waves transmitted by other subscriber stations. As a result, the burst signal is transmitted to the time slot assigned to the own station.

From the perspective of the base station, the fixed propagation time difference based on the distance difference between the base station and each subscriber station is eliminated even by adjustment at the time of initial construction, but environmental conditions such as room temperature, power supply voltage, etc. Fluctuations in equipment characteristics of subscriber stations due to
Due to changes in humidity and changes in propagation time due to rainfall,
The reception timing of the burst signal from each subscriber station varies, although slightly. As a countermeasure against these fluctuations, conventionally, a small guard time is provided between burst signals from each subscriber station to minimize the fluctuation amount based on the device characteristics.

[Problems to be Solved by the Invention]

Due to the above-described countermeasure against fluctuations, no particular problem has occurred in the conventional multi-directional multiplex wireless communication system having a relatively low data transmission speed (small transmission capacity). However, when the data transmission speed is increased to meet the demand for large capacity and high efficiency transmission, the reception timing fluctuation of the burst signal becomes relatively large with respect to the bit length (1 bit time) of the data signal. However, there is a problem that the above-mentioned conventional measures have a limit and a code error is generated, and development of effective means is desired.

An object of the present invention is to provide a multi-directional multiplex wireless communication system capable of absorbing the above-mentioned fluctuations in the reception timing in the base station and enabling large capacity and high efficiency transmission without complicating the configuration of each subscriber station. It is to be.

[Means for solving the problem]

The multidirectional multiplex wireless communication system of the present invention is a multidirectional multiplex wireless communication system in which digital communication is performed between a base station and a plurality of subscriber stations by a TDM-TDMA system, in which each subscriber station extracts a clock component. Suitable for each of the acquisition signals, which are alternately 1 and 0, are sequentially transmitted to a common time slot according to a command from the base station or a predetermined order, and the base station receives each of the subscription signals from the received acquisition signals. The clock component of the data signal transmitted by the mobile station is extracted, the extracted clock component and the multiphase clock signal generated in the base station are compared in phase, and the phase closest to the extracted clock component in the multiphase clock signal To determine the optimum clock signal for each subscriber station, and output the reproduced data signal of each subscriber station time slot identified and reproduced by each optimum clock signal. It is configured.

〔Example〕

The invention will now be described in greater detail by way of example with reference to the drawings.

FIG. 1 is a block diagram showing the system configuration of an embodiment of the present invention, and FIG. 2 is a timing chart for explaining its operation.

The base station 1 shown in FIG. 1 is composed of a plurality of subscriber stations 2-i (i = 1 to 1).
The TDM signal shown in FIG. 2 (A) is transmitted to (n). T
In one frame of the DM signal, the timing reference signal R, the common control signal C, and subsequently the information signal Di for each subscriber station are allocated in a time division manner, and each subscriber station 2-i has its own timing reference signal R. Therefore, the common control signal C and the information signal Di assigned to the own station are always received. Meanwhile, each subscriber 2-i
Then, as shown in FIG. 2 (B), the burst signal Bi is transmitted to the time slot Ti set for each subscriber station.
This burst signal Bi is generated and transmitted at each subscriber station with reference to the timing reference signal R from the base station,
A slight variation occurs in the burst signal reception timing at the base station due to variations in the characteristics of the equipment at each subscriber station and variations in the propagation time due to weather conditions such as temperature, humidity, and rainfall. Therefore, a guard time To is provided between each time slot Ti so that the burst signals from each subscriber station do not overlap each other.

However, when the data transmission speed becomes faster, the variation of the reception timing becomes a size that cannot be ignored with respect to the bit length of the data signal, so that the base station 1 transmits the data signal sent from each subscriber station by a single clock signal. It becomes difficult to perform identification and reproduction without any error, and code errors increase. In order to prevent this, it is necessary for the base station to control the phase of the clock signal for identification and reproduction for each subscriber station in accordance with the reception timing of the burst signal from each subscriber station. In the present invention, in order to reliably transmit the information necessary for this control, in addition to the burst signal Bi for information transmission from each subscriber station, the acquisition signal Ai suitable for extracting the clock component is provided in the common time slot Tc. It is configured to sequentially send one station to each frame in a predetermined order. The subscriber station 2-1 is shown in FIG. 2 (B).
The solid line indicates the state of transmitting the acquisition signal A ₁ by the subscriber station 2-2, but in the next frame, the subscriber station 2-2 transmits the acquisition signal A ₂ indicated by the broken line to the common time slot Tc. Thereafter, when the subscriber station 2-n similarly transmits the acquisition signal An, the subscriber station 2-n returns to the subscriber station 2-1 again in the next frame, and the above operation is repeated.

The base station receives the acquisition signal Ai, extracts the reception timing information (clock component) of the burst signal Bi from each subscriber station, and uses this to extract the multiphase clock signal generator provided in the own station. Among the output signals, the signal having the closest phase relationship is set as the optimum clock signal, and the signal discriminated and reproduced by this optimum clock signal is selectively output, whereby a reproduced data signal having no code error can be obtained. Since the capture signal is a signal suitable for extracting the clock component, it is possible to reliably extract the reception timing information in a short time, and since it has been conventionally used for adjustment at the time of initial construction, It can be easily delivered with almost no changes. The fluctuation of the reception timing described above
Repetition period (n of the acquisition signal transmitted from each subscriber station
It is slow (once a frame) and can sufficiently follow fluctuations even if a capture signal is used.

FIG. 3 is a block diagram showing the configuration of an embodiment of the identification reproducing section of the receiving device of the base station 1. The baseband signal of each time slot Ti demodulated by the demodulator 3 of the receiving apparatus is identified by m clock signals φ _{1 to} φm generated by the polyphase clock signal generator 5 using m different phases. Bowl 4
-1 to 4-m, the outputs of the respective discriminators are read again by a common clock signal in the read phase matching circuit 6 and converted into a signal having a matched phase, and then the data memory 7 is used. Memorized in. On the other hand, the output of the demodulator 3 is branched and applied to the timing extraction circuit 8, where the clock component is extracted from the acquisition signal Ai of the common time slot Tc, and the timing signal representing the reception timing of the subscriber station 2-i. 101 is extracted. The timing signal 101 is phase-compared with the reference clock signal 102 from the multi-phase clock signal generator 5 by the phase detector 9, and its output is held by the sample hold circuit 10 until the next acquisition signal Ai is received. . This output is applied to the phase determination circuit 11, where the optimum clock signal having the optimum phase relationship among the multiphase clock signals φ _{1 to} φm is determined. A control signal 103 for controlling the data selection circuit 12 is sent out according to the result of this determination, and a reproduced data signal having no code error identified by the optimum clock signal is selectively output from the data memory 7. The control signal 104 of the sample hold circuit 10 is a control signal for matching the sampling period with the reception period of the capture signal Ai. It is not necessary to continuously adjust the phase of the clock signal for identification and reproduction. If the number of phases of the multi-phase clock signal generator 5 is set appropriately, the purpose of preventing the occurrence of code error can be achieved, and the base station reception This is effective because it does not complicate the configuration of the device.

In the embodiment shown in FIG. 3, m discriminators 4-1 to 4-m operating with multiphase clock signals φ _{1 to} φm are provided, and data is reproduced from among m sets of reproduced data signals which have been discriminated and reproduced. Although the selector circuit 12 is configured to selectively output the reproduction data signal processed by the optimum clock signal, the discriminator selects the optimum clock signal from the m multiphase clock signals as one discriminator. However, the same effect can be obtained even if it is configured to be added to the discriminator. Also, the phase detector 9 is configured to compare the phase with one of the multi-phase clock signals and determine the optimum clock signal from its output. However, a plurality of phase detectors may be used. A method is also possible. Further, in the above description, each subscriber station is assumed to transmit the acquisition signal in a predetermined order, but it may be transmitted according to a command from the base station.

〔The invention's effect〕

As described in detail above, according to the multi-directional multiplex wireless communication system of the present invention, the acquisition signal can be transmitted with almost no change to the subscriber station device, and the acquisition signal is transmitted from the acquisition signal on the base station side. The timing information can be reliably extracted with a simple circuit, and fluctuations in the reception timing can be absorbed by selecting the optimum clock signal from the multi-phase clock signals. There is an effect that can be configured.

[Brief description of drawings]

FIG. 1 is a block diagram showing the system configuration of an embodiment of the present invention, FIGS. 2A and 2B are timing charts for explaining the operation of FIG. 1, and FIG. 3 is a base station receiver. FIG. 3 is a block diagram showing an example of the identification reproduction unit of FIG. 1 ... Base station, 2-i (i = 1 to n) ... Subscriber station, 3 ...
... demodulator, 4-j (j = 1 to m) ... discriminator, 5 ... multi-phase clock signal generator, 6 ... read phase matching circuit, 7 ...
... Data memory, 8 ... Timing extraction circuit, 9 ... Phase detector, 10 ... Sample hold circuit, 11 ... Phase determination circuit, 12 ... Data selection circuit.

Claims (1)

(57) [Claims] 1. A multidirectional multiplex wireless communication system for performing digital communication between a base station and a plurality of subscriber stations by a time division multiplex / time division multiple access system, wherein each subscriber station extracts a clock component. Appropriate alternating 1 and 0 acquisition signals are sequentially transmitted to a common time slot according to a command from the base station or a predetermined order, and the base station receives each of the subscribers from the received acquisition signals. The clock component of the data signal transmitted by the station is extracted, the extracted clock component and the multiphase clock signal generated in the base station are phase-compared, and the phase closest to the extracted clock component in the multiphase clock signal is determined. Determining the optimum clock signal for each subscriber station and outputting the reproduction data signal of each subscriber station time slot identified and reproduced by each optimum clock signal. Multidirectional multiplex radio communication system according to symptoms.