JPH01240025A - Concentrating distributing system - Google Patents

Abstract

PURPOSE:To effectively secure the regular property and the continuity of communication information by receiving from a central device through a channel in a base station, delay-controlling information to radio-transmit, to a moving station for the time difference of a constant time found in advance and the propagation delay time of the information transmitted from the central device and transmit-outputting it to the moving station. CONSTITUTION:A delay control part 21 calculates the time difference (D= Tconst-Td) with a constant time Tconst found based on system specification in advance according to a signal propagation delay time Td to the central device 1. Here, the constant time Tconst is set as a maximum propagation time or the like to the most remote base station from the central device 1. After a receiving signal is delayed at a delay circuit 15 for the above time difference D, communication information is radio-communicated from a transmitter/receiver 17 to a moving station 4. Thus, the transmitting timing of the communication information radio-transmit-outputted from respective base stations 3a-3n is coincident-controlled mutually. Consequently, when the switching of the base station is executed with the moving of the moving station 4, the problem of a bit dropping, the inserting of an unnecessary bit or the like is not generated.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Industrial Application Field) The present invention provides a mobile communication system that selectively passes through a plurality of base stations serving as east line distribution terminals connected to a central unit via a transmission line. The present invention relates to a line concentration and distribution system that does not cause problems such as dropped bits of communication information or insertion of unnecessary bits when switching base stations, in a wireless communication system that performs information communication between base stations.

(Prior art) When constructing a line switching network between communication terminal devices such as telephones and data terminals, it requires a large amount of equipment expense to install individual communication lines between the exchange and multiple communication terminal devices. I need. Therefore, concentrating and distributing terminals are installed at key points, trunk transmission lines are laid between these concentrating and distributing terminals and the central equipment (exchange), and each of the communication terminals is connected to the nearest concentrating and distributing terminal. The idea is to build a net.

A network based on such a line concentration distribution system basically allocates time slots individually to line concentration distribution terminals receiving data transfer requests from communication terminal devices using time division multiple access (TDMA). Then, information is transmitted between the central device and a plurality of east line distribution terminals in a time-division manner for each of the time slots via a transmission path, thereby realizing information communication between the communication terminal devices.

By the way, it has been considered to apply such a line concentration distribution system to construct a mobile radio communication system as shown in FIG. 6, for example. That is, a plurality of base stations 3a as east line distribution terminals connected to the central device 1 via the transmission line 2,
3b, ~3n are provided for each predetermined wireless communication service area, and selective wireless communication is performed between the mobile station 4 and the base stations 3a, 3b, ~3n according to the wireless communication service area, and the base station 3a .

3b and 3n.

By the way, in such a mobile radio communication system,
As the wireless communication service area in which the mobile station 4 is located changes, the base station with which the mobile station 4 performs wireless communication is switched. At this time, the base station 3a.

It is said that the continuity of wirelessly communicated information signals is impaired due to differences in frame phases between the base stations 3a, 3b, and 3n due to differences in signal propagation time differences between the base stations 3b and 3n and the central device 1. A problem occurs.

That is, as illustrated in FIG. 7, communication information transmitted from the central unit 1 in time slot Ta is first received by a distant base station (MAU), and then the clock rate is lowered and the communication information is transmitted in the narrow band. It is assumed that wireless transmission is being performed to the mobile station 4 in a band-wide manner.

As the mobile station 4 moves, the base station in charge of relaying the communication information is switched, and this time, the base station (MAU1) connected to the central unit 1 is connected to the central unit 1 at a position close to the central unit 1. It is assumed that the communication information from the mobile station 4 is narrowbanded and wirelessly transmitted to the mobile station 4. In this case, when communication information is sent from the central device 1 in the same time slot Ta, it is sent to the base station (MAU, MAU,
) of J Due to the difference in signal propagation time due to the difference in connection distance,
A shift occurs in the absolute time timing of the J communication information reaching the base station (MAU, MAU,).

As a result, in the example shown in FIG. 7, a problem arises in that a part of the signals transmitted to the mobile station 4, or in other words, received by the mobile station 4, overlap due to the switching of the base station. Particularly in the case of digital communications, such signal overlap causes problems such as bit sequences being dropped during the overlap period, disrupting the regularity of the information signal sequence and making signal reproduction impossible.

Furthermore, when switching from a nearby base station to a distant base station occurs, the communication information is interrupted due to a shift in arrival timing of the communication information due to a similar difference in propagation delay time. As a result, the signal sequence is disturbed by including unnecessary information in the interrupted section, and problems such as loss of synchronization and interference with reproduction of communication information occur.

In order to avoid such problems, it is conceivable to provide the mobile station 4 with independent modulators for the two base stations, and use the modulators to absorb timing differences in information wirelessly communicated from each base station. .

However, installing multiple modulators and demodulators in a mobile station unnecessarily complicates the configuration and increases the cost of the equipment.Furthermore, in order to absorb and control discrepancies in the timing of information reception, frame detection for the received signal is required again. Problems such as
Problems arise, such as an increase in the processing load on the mobile station.

(Problems to be Solved by the Invention) In a mobile radio communication system constructed by applying the line concentration distribution method as described above, when the base station (line concentration distribution terminal) is switched due to the movement of the mobile station, the Due to differences in information propagation time due to differences in the connection distance of the base station to the central equipment, bits may be dropped or unnecessary bits may be inserted in the information sequence wirelessly transmitted to the mobile station, causing the information signal sequence received by the mobile station to deteriorate. Disturbances occur in the mobile station, and solving such problems inevitably increases the configuration and processing load of the mobile station.

The present invention has been made in consideration of these circumstances, and its purpose is to sufficiently ensure the regularity and continuity of the information signal sequence given to the mobile station even when switching base stations. The objective is to provide a highly practical mobile radio communication system.

[Structure of the Invention] (Means for Solving the Problems) The present invention selectively communicates wirelessly with a mobile station, and connects information wirelessly communicated with the mobile station via a transmission path. In a line concentration distribution method applied to a mobile radio communication system equipped with a plurality of base stations that relays information communication between the mobile station and the central unit by time-division multiplexing and transmitting between the mobile station and the central unit. , the information received by the base station from the central unit via the transmission path and wirelessly transmitted to the mobile station is transmitted from the central unit to the onst via the transmission path for a predetermined fixed time T. Propagation delay time T of information coming
Delayed by the time difference (T − T,) d
const control, and this delay-controlled information is transmitted and output to the mobile station.

(Operation) According to the present invention, for example, the signal propagation delay time T to each base station is subtracted from the fixed time T, which is expected to be the maximum signal propagation delay time to the farthest connected base station. Since the information wirelessly transmitted from each base station to the mobile station is delayed, the timing of the signal wirelessly transmitted from each base station and received by the mobile station can be made constant. Strictly speaking, the base stations that are switched as the mobile station moves are adjacent base stations, and the propagation time of information wirelessly communicated from these base stations to the mobile station is almost constant, and the The timing difference can be almost ignored.

Therefore, by absorbing the difference in propagation delay time of information transmitted from the central unit to each base station and applying the delay control described above so that the timing of information wirelessly transmitted to the mobile station is equal among multiple base stations, mobile It becomes possible to effectively ensure the regularity and continuity of communication information without complicating the configuration of the station or increasing the processing load.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows the concept of delay control performed in a mobile radio communication system to which a line concentration distribution method according to an embodiment of the present invention is applied, and FIG. 2 shows a base station that performs this delay control. (MAU) is a schematic configuration diagram of main parts.

In FIG. 2, a demodulator 11 demodulates communication information from the central unit 1 received from the transmission line 2 via a diplexer 12. The frame decomposition unit 13 is the demodulator 1
Under the control of the propagation delay control unit 14, the communication information of the time slot assigned to itself is extracted from the signal sequence demodulated in step 1.

The communication information extracted by the frame decomposition unit 13 is subjected to delay control via a delay circuit 15, which will be described later, and then is transmitted from the modulator 16 to the mobile station 4 via the transceiver 17.

Further, communication information from the mobile station 4 is received from the transceiver 17 via the demodulator 18, and a frame synthesis section 19 synthesizes frames inserted into predetermined time slots.

The signal is then outputted from the diplexer 12 to the transmission line 2 via the modulator 20, and then transmitted to the central device 1.

The propagation delay control unit 14 transmits and receives a predetermined training signal to and from the central device 1, measures the signal propagation time during information communication with the central device 1 via the transmission path 2, and performs the frame synthesis. The signal transmission timing from section 19 in a predetermined time slot is controlled. By controlling this signal transmission timing, a plurality of base stations 3a are connected to the transmission line 2.

Collision of communication information transmitted from 3b and 3n in each time slot is prevented.

By the way, the delay circuit 15 delays communication information to be wirelessly transmitted to the mobile station 4 under the control of the delay control section 21 as follows.

That is, the delay control unit 21 calculates the time difference (Donst -T -Td) and calculate this time difference before
st is set as the delay time by the delay circuit 15.

Here, the above-mentioned fixed time T is from the central device l to ons
t This is set as the maximum propagation time, etc. for the base station connected to the farthest position (distance), and is uniquely determined in the communication system. Such a certain period of time T
After the received signal is delayed by the delay circuit 15 by the time obtained by subtracting the signal onst propagation time Td from to each base station, this communication information is transmitted to the transceiver 17.
By wirelessly communicating with the mobile station 4 from the mobile station 4, as shown in FIG. 1, the transmission timings of the communication information wirelessly transmitted and outputted from each base station 3a, to 3n are controlled to be consistent with each other.

Therefore, according to this system in which such delay control is applied, when base stations are switched as the mobile station 4 moves, the timing of information wirelessly transmitted from the adjacent base station to the mobile station is Since the timing matches the timing of the signal being transmitted, it is possible to switch the received signal series without causing problems such as dropping bits or inserting unnecessary bits.

As a result, base stations can be switched very smoothly and information communication can be continued.

The propagation delay time mentioned above is, for example,
It is measured using the method disclosed in No. 134 and the like.

However, the propagation delay time T1. measured by this method. are the total propagation delay time of the signal transmitted from the base station to the central equipment l and then looped back from the central equipment l to the base station, that is, the upstream signal transmission delay time T and the downstream signal transmission delay time T .

It becomes the addition of. Therefore, the propagation delay time controller 1
4, the propagation delay time T9. The propagation delay time T used for the above-mentioned delay control may be set as half (1/2) of the above-described delay control.

However, in reality, the above-mentioned propagation delay time Tp includes signal delays T and T within the modem, and it is necessary to
d.

It does not become sushimo (T - Td). However, transmission line 2
Since the delay elements other than the above can be considered to be constant for each base station (MAU), the accurate propagation delay time from the central unit 1 to the base station is Td - Tdo + Tdn, and ( Tuo-T, .)/2. However, in the above formula, it is regarded as (Tdn-Tun). However, this offset is
U) The above-mentioned constant time T is constant regardless of the connection position of 3a, 3b, to 3n to the transmission line 2. onst, and can be virtually ignored.

Therefore, by the above-described delay control based on the propagation delay time T obtained in this way, the mobile station 4
Since the timings of the information wirelessly transmitted can be effectively matched, the base station can be switched very smoothly and effectively with simple control.

By the way, the problem of the timing of information communicated from the central device 1 to the mobile station 4 via the base stations 3a to 3n can be effectively solved by the delay control described above.
Timing deviation in information transmission from the mobile station to the central device 1 via the base stations 3a, -3n, that is, the base stations 3a, -3n
The timing shift of information received from the mobile station at 3n can be resolved as follows.

Specifically, as shown in FIG. 3, information wirelessly communicated from the mobile station 4 to the base station is determined by the maximum propagation delay between the base stations 3a, 3n and the mobile station 4 for the frame time length. Wireless communication is performed in bursts so that the time is shorter than (dR+dT).

In this way, the communication information from the mobile station 4 will always be received before the base stations 3a, -3n send out the signals to the central unit l, so the timing problem can be effectively avoided. Can be done.

Furthermore, as shown in FIG. 4, the phase of the timing of wirelessly communicating information from the base stations 3a, ~3n to the mobile station 4, and the timing of wirelessly communicating information from the mobile station 4 to the base stations 3a, ~3n, is It is also possible to set the phase shift and absorb the phase shift at the base stations 3a to 3n. However, in this case, it is necessary to set the signal timing within the maximum phase range T that can be absorbed by the base stations 3a to 3n.

Further, as shown in FIG. 5, the mobile station 4 connects to the base station 3a.

The timing (frame phase) of the information to be wirelessly transmitted from 3n to 3n may be set earlier than the timing of the received signal by a certain value. In this case, the base station 3a
, ~3n and the mobile station 4 by the time required to account for the maximum propagation delay Tq.

By employing such a method, it becomes possible to smoothly perform the above-mentioned base station switching without any adjustment work at the mobile station 4. In other words, it is possible to effectively switch between base stations simply by controlling the timing on the base station side.

Note that the present invention is not limited to the embodiments described above. For example, for information transmission between the central device 1 and the base stations 3a to 3n, not only the TDMA method but also various other methods can be adopted. It is also possible to convert the communication information from the mobile station into multi-frames and transmit the information to and from the central device. Furthermore, if the time slot for information transmission with the central device l is changed due to switching of base stations, the timing shift can be adjusted at the base stations 3a, 3n. , can be controlled independently of the delay control described above. Furthermore, it is also possible to measure the propagation delay time at the base stations 3a, .about.3n by the central device 1, and notify the propagation delay time information to each base station 8a, .about.3n, thereby performing the aforementioned delay control. .

Alternatively, the central device 1 may calculate the delay control time at each base station 3a, .about.3n, and notify each base station 3a, .about.3n of the delay control time information. In addition, the present invention can be implemented with various modifications without departing from the gist thereof.

[Effects of the Invention] As explained above, according to the present invention, it is possible to effectively absorb the difference in received information timing due to differences in information propagation delay time to a plurality of base stations (concentration distribution terminals), and to Since the timing of wirelessly transmitting information can be made constant through simple control, base station switching can be performed very smoothly as the mobile station moves, and it also reduces the complexity of the mobile station configuration and processing burden. This has great practical effects, such as not causing an increase in the amount of water.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the concept of delay control executed in a mobile radio communication system to which a line concentration distribution method according to an embodiment of the present invention is applied, and FIG. 2 is a diagram showing a base station (
3 to 5 are diagrams showing the form of information transmission control from the mobile station to the base station applied to the embodiment system, and FIG. 6 is a diagram showing the configuration of the main parts of the MAU (MAU), and FIG. FIG. 7 is a schematic configuration diagram of a mobile radio communication system according to the present invention, and is a diagram for explaining problems when switching base stations in the conventional system. ■...Central device, 2...Transmission line, 3a, 3b, ~
3n... Base station (concentration distribution terminal), 4... Mobile station,
13... Frame decomposition unit, 14... Propagation delay control unit, 15... Delay circuit, 17... Transmitter/receiver, 19...
- Frame synthesizer, 21...delay control unit. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4 Figure 6

Claims (1)

[Claims] Selective wireless communication is performed with a mobile station, and information communicated wirelessly with the mobile station is time-division multiplexed with a central device connected via a transmission path. In a concentrating and distribution method for constructing a mobile radio communication system including a plurality of base stations that transmit data in the same manner, the base station receives information from a central device via the transmission path and wirelessly transmits the information to the mobile station. The transmission output is delayed by a time difference (T_c_o_n_s_t−T_d) between a predetermined fixed time T_c_o_n_s_t and a propagation delay time T_d of information transmitted from the central device via a transmission path. Concentration distribution method.