JPH04162840A - Transmission timing synchronizing method using absolute time - Google Patents

Abstract

PURPOSE:To keep the timing between radio base stations constant without provision of a control line for timing synchronization by sending a signal based on a time of a clock ticking in an absolute time in its own station at each reference station. CONSTITUTION:Each radio base station 34 make a request of absolute time information to a reference time station 32 periodically. The reference time station 32 sends back an absolute time on request against the request from each radio base station 34 as absolute time information 37 via a subscriber line 33 and a network. Then each radio base station 34 based on the received absolute time information 37 adjusts the time of a lock clock 35 of its own station so as to be an absolute time. Moreover, each radio base station 34 decides a timing of a transmission signal based on the clock of the local clock 35 of its own station and sends the signal and the timing of lie control is matched similarly based on the time of the local clock 35. Thus, the signal transmission timing and a control timing between the radio base stations 34 are matched in an accurate timing without provision of an exclusive line for adjusting timing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for mutually adjusting signal timings transmitted from a plurality of base stations and control timings in a mobile communication system.

(Prior Art) Until now, no method has been reported for matching the timings of transmission signals or control between bases. However, an easily envisioned method is to establish dedicated lines for mutual synchronization between radio base stations and to achieve synchronization by distributing timing signals.

FIG. 6 is a configuration diagram showing the above-mentioned conventional example. In the figure, 11 is a wireless base station, 12 is a network, 13 is a leased line, 14 is a mobile device, 15 is a base station transmission signal, and 16 is a timing generation station. The conventional operation is as follows. A timing signal generated by a timing generation station 16 is transmitted to each wireless base station 11 via a dedicated line 13. Each radio base station 11 adjusts the output timing of the transmission signal at this timing.

FIG. 7 is a timing chart showing waveforms of timing signals of various parts. As can be seen from the figure, the timing generation station 16 in FIG. 6 generates a plurality of timing signals (1) to (2). These multiple timing signals are multiplexed and transmitted as one signal over a dedicated line. The wireless base station extracts multiple timings from this signal and uses them as various timings such as the transmission timing of the wireless transmission signal, the signal switching timing between base stations, the line control timing, etc. (Problem to be solved by the invention) However, the above-mentioned conventional In this method, since timing information is transmitted via a dedicated line, it is necessary to connect two lines, a speech line and a dedicated line, to all multiple base stations.
There is a problem in that equipment costs increase due to construction work. In addition, when providing services across multiple carriers,
Since the leased line must be connected to the base stations of all carriers, there are problems such as limitations in system design.

In order to eliminate these problems, the present invention makes it possible to match the transmission and control timings of each base station without providing a special dedicated line for transmitting timing information.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a mobile communication system configured by connecting a plurality of wireless base stations to subscriber lines of a network. The feature is that a clock that keeps track of absolute time is installed inside the terminal or inside the terminal connected to the subscriber line.

(Operation) According to the present invention having the above-described configuration, each radio base station periodically makes an inquiry to a node or a terminal regarding the absolute time via the network. In response to this inquiry, the node or terminal transfers absolute time information to the wireless base station, and adjusts the clock owned by the base station in the wireless base station based on the transferred absolute time information so that it always has absolute time. Then, each radio base station uses the time of its own clock as the timing for transmitting a signal or the timing for establishing a radio link, and adjusts the timing between the radio base stations.

Therefore, the present invention can solve the above problems, and can match the transmission and control timings of each base station without providing a special dedicated line for transmitting timing information.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention. This embodiment uses the following terminal (which has a clock that keeps track of absolute time (for example, Japan Standard Time, etc.) on the subscriber line of the network.
This is an example in which a terminal (hereinafter referred to as a reference time station) is connected. In the figure, 31 is a clock that keeps track of absolute time, 32 is a reference time station that has the clock 31, 33 is a subscriber line, 34 is a radio base station that has a local clock 35 (described later), 35 is a local clock, and 36 is a mobile device. , 37 are absolute time information, and 38 shown in FIG. 2 is a wireless transmission signal.

Next, the operation of the first embodiment will be explained.

First, each wireless base station 34 periodically transmits the reference time station 32.
requests absolute time information. In response to requests from each wireless base station 34, the reference time station 32 sends back the absolute time at the time of receiving the request as absolute time information 37 via the subscriber line 33 and the network. Each radio base station 34 adjusts the time of its own local clock 35 to be the absolute time based on the received absolute time information 37. Each radio base station 34 determines the timing of a transmission signal based on the time of its own local clock 35 and transmits the signal. Similarly, the timing of line control is adjusted based on the time of the local clock 36. In this way, by installing a clock that keeps track of absolute time at each radio base station and periodically adjusting this clock, it is possible to
As shown in FIG. 2, it becomes possible to match the signal transmission timing and control timing between wireless base stations with accurate timing.

FIG. 3 is a block diagram showing a second embodiment of the present invention. In this embodiment, a clock that keeps track of absolute time is placed in one of the nodes in the network. In the same figure, the same reference numerals as in FIG. 1 indicate the same components, and the different components include a reference time station 41 which is a node in the network, and 42 a reference time station provided in the reference time station. It's a clock. The operation is almost the same as that of the first embodiment, so a description thereof will be omitted.

Next, a specific method for adjusting the clock of the radio base station to the absolute time of the reference clock station will be described. However, the following two points must be met.

■The amount of delay between two points (reference clock station and wireless base station) changes. However, the rate of change is assumed to be slower than the transfer rate of time information.

(2) Assume that the delay fluctuations up and down the transmission path are equal.

(On a network, data is always transmitted in pairs.) Time adjustment of the radio base station clock is performed in two steps: frequency adjustment and absolute time adjustment.

[Frequency Adjustment] FIG. 4(a) shows a principle diagram of clock frequency adjustment between the clock of the reference clock station and the radio base station.

The frequency adjustment operation is as follows.

Each station calls out the absolute time of the reference clock at regular intervals using its own clock. A station that has a clock with an absolute time as a reference notifies the absolute time of the call each time it is called. This call is made twice, and the difference between the two absolute times obtained is determined and compared with the fixed time value determined by the local station's clock.

Specifically, if a call is made from a wireless base station at 100 second intervals (local clock) and the times when time inquiries are received at the reference time station are 500 seconds and 602 seconds, the frequencies of the clocks of the wireless base station and the reference time station are The ratio becomes 102 to 100, and the frequency of the wireless base station clock is adjusted based on this.

[Absolute Time Adjustment] FIG. 4(b) shows a principle diagram of absolute time adjustment between the clock of the reference clock station and the radio base station.

The operation for adjusting the absolute time is to make a call once after adjusting the frequency, measure the delay time until a response is returned, and adjust the absolute time using the absolute time included in the response.

Specifically, if the time of the wireless base station at the time of inquiry is 0 seconds, the absolute time of the reference clock station at the time of inquiry is 500 seconds, and the delay time is 1 second, the upstream and downstream delays are set to 0.
5 seconds, and as a result, it is understood that it is sufficient to advance the clock of the wireless base station by 499.5 seconds.

FIG. 5 is a block diagram showing a model for synchronizing base stations of different carriers using analog subscriber lines. In the figure, 61 is a service zone of each different carrier, 62 is an analog modem, and 63 is an analog subscriber line. The operation is as shown in FIG. 4, by adjusting the frequency and absolute time of the local clock provided in each base station, it is possible to match the transmission and control timings of each base station.

(Effects of the Invention) As explained above, according to the present invention, since each reference station transmits a signal based on the time of the clock that keeps track of absolute time within its own station, a special control line for timing synchronization is required. The timing between the radio base stations can be kept constant without the need to provide one. In addition, since all base station timings are matched to one absolute time, it is possible to not only synchronize the timing of base station transmission signals (but also to synchronize long-cycle timing such as control timing). Since the timing is absolute time, the timing between base stations of multiple carriers can be easily kept constant.

Furthermore, since the timing of the radio base station does not depend on the transmission timing of the transmission line, synchronization between radio base stations can be achieved using not only digital subscriber lines but also existing analog subscriber lines. By connecting the same reference clock stations in a network in a complicated manner, a reserve of reference clock stations can be provided, and as a result, the reliability of the system can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention, FIG. 2 is a timing chart showing timing synchronization, FIG. 3 is a block diagram showing a second embodiment of the present invention, and FIG.
Figure 4 (a) shows the principle of clock frequency adjustment between the reference clock station clock and radio base station, and Figure 4 (b) shows the principle of absolute time adjustment of the clock between the reference clock station clock and radio base station. Figure 5 is a block diagram showing a model that uses analog subscriber lines to synchronize base stations of different carriers; Figure 6 is a block diagram showing a conventional example; 6 is a timing chart showing waveforms of timing signals of each part in FIG. 6. FIG. 31, 42... Clock, 32, 41... Reference time station, 33... Subscriber line, 34... Wireless base station, 35... Local clock, 36... Mobile device, 37. ...Absolute time information, 38...Radio transmission signal. 2nd factor (a) Same wave number - ship f (b) P Togin Gakuno, 2) - 艷 超 - (-"
-One Town Seiji Diagram 4/& Next Convention Diagram 6

Claims (1)

[Claims] In a mobile communication system configured by connecting a plurality of wireless base stations to a subscriber line of a network, absolute time information is transmitted within one node within the network or within a terminal connected to the subscriber line. Each wireless base station periodically queries the node or the terminal for absolute time via a network, and in response to the inquiry, the node or the terminal transmits absolute time information to the wireless base station. The base station's clock within the wireless base station is adjusted based on the transferred absolute time information so that it always has absolute time, and each wireless base station adjusts the signal based on the time of its own clock. A transmission timing synchronization method using absolute time, characterized in that the timing is used as the transmission timing or the timing for establishing a wireless link, and the timing is adjusted between wireless base stations.