WO2006008809A1

WO2006008809A1 - Wireless communication method and base station

Info

Publication number: WO2006008809A1
Application number: PCT/JP2004/010333
Authority: WO
Inventors: Naoyuki Sugiyama
Original assignee: Mitsubishi Denki Kabushiki Kaisha; Utsumi, Yoshinori
Priority date: 2004-07-21
Filing date: 2004-07-21
Publication date: 2006-01-26

Abstract

A wireless communication method comprising an interference measurement step in which an absolute synchronization base station (1a), which re-synchronizes radio frames, measures any interference caused by any peripheral base station when, for example, a predetermined re-synchronization time has come, and a re-synchronization execution determination step in which if there exists any interference caused by any peripheral base station, and a difference between a first phase difference between a GPS signal and a radio frame obtained during the previous re-synchronization and a second phase difference between a current GPS signal and a current radio frame is equal to or greater than a predetermined threshold value, then a radio frame re-synchronization is executed; on the other hand, if there exists no interference caused by any peripheral base station, or if there exists any interference caused by any peripheral base station and the difference between the first and second phase differences is smaller than the predetermined threshold value, no radio frame re-synchronization is executed.

Description

Specification

Wireless communication method and base station

Technical field

[0001] The present invention relates to a radio communication method in a system in which a plurality of base stations are connected via a mobile network. Specifically, the phase of a radio frame is adjusted (re-established every predetermined time). The present invention relates to a wireless communication method that performs synchronization processing.

Background art

Hereinafter, a conventional wireless communication system will be described. In a conventional wireless communication system, an absolute synchronization base station that adjusts the phase of a frame signal with reference to a GPS signal at a predetermined resynchronization time and transmits the adjusted frame signal, and a frame sent from the absolute synchronization base station. A subordinate synchronization base station that adjusts the phase of the internal frame signal so as to match the phase of the frame signal, and at the predetermined resynchronization time, the absolute synchronization base station and the subordinate synchronization base station must always Perform frame resynchronization processing.

[0003] Also, if it is found that a call in communication has occurred before the predetermined resynchronization time, the absolute synchronization base station and the subordinate synchronization base station transfer the call to the other terminal. The base station is instructed to perform handover, and the radio frame is resynchronized when the call disappears (see Patent Document 1 below).

Patent Document 1: Japanese Patent Application Laid-Open No. 2002-354536, FIG.

Disclosure of the invention

Problems to be solved by the invention

[0005] However, in the conventional radio communication system described in the above-mentioned document, the radio frame resynchronization processing is always performed when the absolute synchronization base station and the subordinate synchronization base station reach a predetermined resynchronization time. Therefore, for example, a base station that is performing radio frame resynchronization processing has a problem that it cannot communicate until the resynchronization processing is completed.

[0006] Also, in the conventional radio communication system, when it is determined that a call in communication has occurred at the time of performing the resynchronization process of the radio frame, the call is handed over to another base station. For example, when a handover destination base station is not found, there is a problem in that a call in communication is forcibly disconnected.

The present invention has been made in view of the above, and provides a wireless communication method that maintains a communicable state without performing a wireless frame resynchronization process when the resynchronization process is unnecessary. The purpose is to provide.

[0008] It is another object of the present invention to provide a wireless communication method that can continue a call during communication without forcibly disconnecting even when performing resynchronization processing of a wireless frame.

Means for solving the problem

[0009] A wireless communication method according to the present invention is a wireless communication method by a base station that adjusts (resynchronizes) a phase of a wireless frame based on a GPS (Global Positioning System) signal, for example, An interference measurement step for measuring interference from neighboring base stations when a predetermined resynchronization time is reached, and if there is interference from neighboring base stations, the GPS signal and radio frame from the previous resynchronization process If the difference between the first phase difference between the current GPS signal and the second phase difference between the current GPS signal and the radio frame is equal to or greater than a specific threshold, the radio frame resynchronization process is executed. On the other hand, if there is no interference from neighboring base stations, or there is interference from neighboring base stations, the difference between the first phase difference and the second phase difference is a specific threshold value. If not, do not execute the resynchronization process of the radio frame. And resynchronization processing execution determination step, characterized in that it comprises a.

[0010] According to the present invention, whether the base station measures the interference state of the frame signal before performing the radio frame resynchronization process, and performs the radio frame resynchronization process based on the measurement result. For example, if it is determined unnecessary, the radio frame resynchronization process is not performed.

The invention's effect

[0011] Therefore, it is possible to avoid a communication disabled state due to useless resynchronization processing as in the prior art. For example, when it is determined that radio frame resynchronization processing is unnecessary, current communication is maintained. There is an effect that it is possible.

Brief Description of Drawings

FIG. 1 is a block diagram of a wireless communication system for realizing a wireless communication method that is effective for the present invention. FIG.

[Figure 2] Figure 2 shows the phase relationship between the GPS signal at the previous resynchronization and the radio frame of the absolute synchronization base station, and the phase relationship between the radio frame of the absolute synchronization base station and the radio frame of the subordinate synchronization base station. FIG.

[Fig. 3] Fig. 3 shows an example of the phase relationship between the GPS signal at the time of resynchronization and the radio frame of the absolute synchronization base station, and the phase relationship between the radio frame of the absolute synchronization base station and the radio frame of the subordinate synchronization base station. FIG.

FIG. 4 is a flowchart showing a radio frame resynchronization process according to the first embodiment.

FIG. 5 is a diagram showing an example of a phase relationship between a radio frame at the time of resynchronization in the subordinate synchronization base station and a radio frame at the time of resynchronization in the absolute synchronization base station.

FIG. 6 is a flowchart showing a radio frame resynchronization process according to the second embodiment.

FIG. 7 is a flowchart showing a handover process by all base stations that may be a handover destination.

FIG. 8 is a flowchart showing a handover process by a base station (handover source base station) in communication with a terminal.

Explanation of symbols

[0013] la, lb absolute synchronous base station

2a, 2b GPS receiver

3a, 3b Dependent synchronous base station

4 Mobile network

5 Network management device

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of a wireless communication method according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment.

[0015] Embodiment 1.

FIG. 1 shows a configuration of a wireless communication system for realizing a wireless communication method according to the present invention. FIG. This wireless communication system is connected to absolute synchronized base stations la and lb that adjust the phase of the frame signal based on the GPS signal, and transmits the adjusted frame signal, to the absolute synchronized base station, and at the resynchronization time. Then, the GPS receivers 2a and 2b that receive GPS signals from GPS satellites, and the subordinate synchronization base station that adjusts the phase of the internal frame signal to match the phase of the frame signal sent from the absolute synchronization base station la 3a, 3b, slave synchronization base stations 3c, 3d that adjust the phase of the internal frame signal to match the phase of the frame signal sent from the absolute synchronization base station lb, the mobile network 4, and the mobile A network management device 5 for managing a network 4, an absolute synchronization base station la-lb, a GPS receiver 2a-2b, and a slave synchronization base station 3a 3d.

[0016] Next, a wireless communication method using the wireless communication system configured as described above will be described.

FIG. 2 shows the phase relationship between the GPS signal at the time of the previous resynchronization and the radio frame of the absolute synchronization base station la, and the radio frame of the absolute synchronization base station 1 a and the radio frame of the dependent synchronization base station 3 a. FIG. GPS signals are received at regular intervals by the GPS receiver 2a. The radio frame of the absolute synchronization base station la is a radio frame after the phase is adjusted (after resynchronization) with reference to the GPS signal, and between the GPS signal and the radio frame of the absolute synchronization base station la. Has a phase difference A.

[0018] FIG. 2 shows a situation in which no interference occurs in the interference monitoring channel of the radio frame of the absolute synchronization base station la due to the interference channel of the radio frame of the dependent synchronization base station 3a.

FIG. 3 shows the phase relationship between the latest GPS signal at the time of resynchronization and the radio frame of the absolute synchronization base station la, and the radio frame of the absolute synchronization base station la and the radio frame of the dependent synchronization base station 3a. FIG. There is a phase difference B between the GPS signal and the radio frame of the absolute synchronization base station la.

[0020] For example, in the communication line connecting the absolute synchronous base stations la and lb, the subordinate synchronous base stations 3a-3d and the mobile network 4, the communication line is disconnected due to poor communication line construction or communication line construction. For example, the phase of the radio frame of the absolute synchronization base station la, lb or / and the dependent synchronization base station 3a 3d varies. FIG. 3 shows a situation in which interference occurs due to the interference channel of the radio frame of the subordinate synchronization base station 3a in the interference monitoring channel of the radio frame of the absolute synchronization base station la.

[0022] Here, when the phase relationship between the radio frame of the absolute synchronization base station la and the radio frame of the dependent synchronization base station 3a changes from the situation shown in FIG. 2 to the situation shown in FIG. The synchronization process will be described. FIG. 4 is a flowchart showing radio frame resynchronization processing according to the first embodiment. For convenience of explanation, in FIG. 3, there is no phase shift in the absolute synchronization base station la (the difference between the phase difference A and the phase difference B is within a predetermined range value). Assume that a phase shift occurs in the synchronized base station 3a.

[0023] First, the absolute synchronization base station la always determines whether or not a predetermined re-synchronization time has been reached (step S1). If the resynchronization time has not been reached (step S I, No), this determination process is repeated until the resynchronization time is reached.

[0024] When the resynchronization time has been reached (step SI, Yes), the absolute synchronization base station la measures the interference with the neighboring base stations using the interference monitoring channel (step S2), and In step S3, it is determined whether or not interference occurs.

[0025] For example, when there is no interference with the neighboring base stations (step S3, No, see Fig. 2), the absolute synchronization base station la performs the processing without executing the radio frame resynchronization processing. End (step S7).

[0026] On the other hand, if there is interference with neighboring base stations (step S3, Yes, see Fig. 3), the absolute synchronization base station la has a phase difference A when the previous synchronization processing is performed. Is compared with the current phase difference B (step S4). Then, it is determined whether or not the comparison result (difference) is within a predetermined threshold value (step S5). It is determined that this is not the cause, and the process is terminated without executing the radio frame resynchronization process (step S7). On the other hand, if the comparison result (difference) is equal to or greater than a predetermined threshold value (step S7). S5, No), it is determined that the interference is caused by the phase shift of the local station, and the radio frame resynchronization process is executed (step S6).

As described above, in the present embodiment, the absolute synchronization base station retransmits the radio frame. Before performing synchronization processing, measure the interference state of the frame signal, determine whether to perform resynchronization processing of the radio frame based on the measurement result, for example, if it is determined that it is unnecessary, Frame resynchronization processing is not implemented. As a result, it is possible to avoid a communication disabled state due to useless resynchronization processing as in the prior art. For example, when it is determined that radio frame resynchronization processing is unnecessary, current communication can be maintained. it can.

[0028] Embodiment 2.

In the first embodiment, the radio frame resynchronization process in the absolute synchronization base station has been described. In the second embodiment, the radio frame resynchronization process in the subordinate synchronization base station will be described. Note that the configuration of the wireless communication system is the same as that of FIG. 1 of the first embodiment described above. In the present embodiment, processing different from that of the first embodiment will be described.

[0029] FIG. 5 shows, for example, a radio frame during resynchronization in the subordinate synchronization base station 3c, a radio frame during resynchronization in the subordinate synchronization base station 3d, and a radio frame during resynchronization in the absolute synchronization base station lb. It is a figure which shows the phase relationship with a flame | frame. FIG. 5 shows that interference caused by the interference channel of the radio frame of the dependent synchronization base station 3d occurs in the interference monitoring channel of the radio frame of the dependent synchronization base station 3c. Interference due to the interference channel of the frame is generated and indicates the status and status.

[0030] Here, radio frame resynchronization processing by the subordinate synchronization base station when the phase relationship shown in FIG. 5 is assumed will be described. FIG. 6 is a flowchart showing radio frame resynchronization processing according to the second embodiment.

[0031] First, the dependent synchronization base station 3c always determines whether or not the re-synchronization time specified in advance has been reached (step S11). If the resynchronization time has been reached or not (step S11, No), this determination process is repeated until the resynchronization time is reached.

[0032] When the resynchronization time has been reached (step Sl l, Yes), the dependent synchronization base station 3c measures interference with the neighboring base station through the interference monitoring channel (step S12), and the neighboring base station It is determined whether or not interference occurs between and (step S13).

[0033] For example, when there is no interference with a neighboring base station (step S13, No), the slave synchronization base station 3c ends the process without executing the radio frame resynchronization process ( Step SI 7).

[0034] On the other hand, if interference has occurred with neighboring base stations (step S13, Yes, see Fig. 5), the dependent synchronization base station 3c searches for the base station type of the interference source ( Step S 14). Then, it is determined whether the base station type of the interference source is an absolute synchronization base station or a dependent synchronization base station (step S15). If all the interference sources are dependent synchronization base stations (step S15, Yes), the radio frame (Step S17), and if there is even one absolute synchronization base station in the interference source (step S15, No), the radio frame resynchronization Execute (Step S16).

[0035] As described above, in this embodiment, the dependent synchronization base station measures the interference state of the frame signal before performing the resynchronization process of the radio frame, and retransmits the radio frame based on the measurement result. Whether or not to perform synchronization processing is determined. For example, if it is determined that the synchronization processing is unnecessary, the radio frame resynchronization processing is not performed. As a result, it is possible to avoid a communication disabled state due to useless resynchronization processing as in the prior art. For example, when it is determined that radio frame resynchronization processing is unnecessary, current communication can be maintained. it can.

Embodiment 3.

In the first and second embodiments described above, the power described for the resynchronization process of radio frames in the absolute synchronization base station and the subordinate synchronization base station. In the third embodiment, the absolute synchronization base station in the case of performing this resynchronization process. And the handover process by the subordinate synchronization base station is explained. The configuration of the radio communication system is the same as that of FIG. 1 of the first embodiment described above. In the present embodiment, processing different from that in the first and second embodiments will be described.

FIG. 7 is a flowchart showing a handover process by all base stations (corresponding to absolute synchronization base stations la and lb and dependent synchronization base stations 3a 3d) that may be a handover destination.

[0038] First, the base station determines whether or not a predetermined resynchronization time has been reached (step S21). If the resynchronization time has not been reached (No at step S21), this determination process is repeatedly executed until the resynchronization time is reached.

[0039] If the resynchronization time has been reached (step S21, Yes), the base station (Step S22), and if possible (Step S22, Yes), a signal indicating that it can become a handover destination to the neighboring base stations (handover possible) Signal) is transmitted (step S23).

FIG. 8 is a flowchart showing handover processing by a base station (handover source base station) in communication with a terminal.

[0041] The base station determines whether or not a predetermined re-synchronization time has been reached (step S31). If the resynchronization time has not been reached (No at step S31), this determination process is repeated until the resynchronization time is reached.

[0042] When the resynchronization time has been reached (step S31, Yes), the base station determines whether a handover possible signal is received from the neighboring base station (step S32) and receives a handover possible signal. If so (step S32, Yes), the base station from which the handover possible signal is selected is selected, and the base station is instructed to perform the handover process (step S33). In addition, when there are a plurality of source base stations that can be handed over, the base station to be handed over is selected based on the order of base station ID, the order in which the signals are received, or random selection. If no handover possible signal has been received (step S32, No), the terminal in communication is instructed to perform the handover process without the selected base station (step S34).

[0043] As described above, in the present embodiment, all base stations notify the neighboring base stations whether they can be a handover destination, while the base stations communicating with the terminals At the time of resynchronization, the base station that can be the handover destination is selected, and the terminal is instructed to perform handover processing on that base station. As a result, it is possible to continue a call being communicated by another base station without forcibly disconnecting the call being communicated as in the prior art.

Industrial applicability

As described above, the radio communication method according to the present invention is useful for a mobile communication system in which a plurality of base stations are connected via a mobile network, and in particular, a radio communication at every predetermined time. Suitable for base stations that perform frame resynchronization processing.

Claims

The scope of the claims

[1] In a wireless communication method by a base station that adjusts (resynchronizes) the phase of a radio frame based on a GPS (Global Positioning System) signal,

An interference measurement step for measuring interference from neighboring base stations when a predetermined resynchronization time is reached;

If there is interference from neighboring base stations, the first phase difference between the GPS signal and the radio frame when the previous resynchronization process was performed, and the second position between the current GPS signal and the radio frame. If the difference from the phase difference is equal to or greater than a specific threshold value, radio frame resynchronization processing is executed. On the other hand, if there is no interference from neighboring base stations, or there is interference from neighboring base stations. And when the difference between the first phase difference and the second phase difference is less than a specific threshold, the step of determining whether to perform resynchronization processing of the radio frame,

A wireless communication method comprising:

[2] If the local station can be a handover destination, whether or not a handover is possible to transmit a signal (handover possible signal) indicating that it can be a handover destination to neighboring base stations A decision step;

When performing the resynchronization process during communication with a terminal and receiving a handover-capable signal from a neighboring base station, the base station selects one of the base stations from which the handover-capable signal is transmitted. Is instructed to perform a handover process on the other hand, while performing the resynchronization process while communicating with the terminal, and receiving a handover possible signal, A handover control step for instructing a communicating terminal to perform a handover process without a selected base station;

The wireless communication method according to claim 1, further comprising:

[3] The phase of the radio frame is adjusted (resynchronization processing) based on the GPS (Global Positioning System) signal, and the phase of the radio frame adjusted by the absolute synchronization base station is matched. In a wireless communication method in a system comprising:

The dependent synchronization base station is An interference measurement step for measuring interference from neighboring base stations when a predetermined resynchronization time is reached;

If there is interference from a neighboring base station, if the neighboring base station of the interference source contains at least one absolute synchronization base station, radio frame resynchronization processing is performed, while interference from neighboring base stations exists. If not, or if there is interference by neighboring base stations and all the neighboring neighboring base stations are subordinate synchronization base stations, a resynchronization process execution determination step that does not perform radio frame resynchronization processing;

A wireless communication method comprising:

[4] The dependent synchronization base station further comprises:

If the local station can be a handover destination, a handover possibility judging step for transmitting a signal (handover possible signal) indicating that it can become a handover destination to neighboring base stations; ,

The wireless communication method according to claim 3, further comprising:

[5] The phase of the radio frame is adjusted (resynchronization processing) based on the GPS (Global Positioning System) signal, and the phase of the radio frame adjusted by the absolute synchronization base station is matched. In a wireless communication method in a system comprising: a subordinate synchronization base station that adjusts a phase of a radio frame of the own station (resynchronization processing);

The absolute synchronization base station is

A first interference measurement step for measuring interference by neighboring base stations when a predetermined resynchronization time is reached;

If there is interference from neighboring base stations, the first phase difference between the GPS signal and the radio frame when the previous resynchronization process was performed, and the first phase difference between the current GPS signal and the radio frame. If the difference between the phase difference of 2 and the difference is equal to or greater than a specific threshold value, radio frame resynchronization processing is executed. On the other hand, if there is no interference from neighboring base stations, And when the difference between the first phase difference and the second phase difference is less than a specific threshold, a first resynchronization process execution determining step that does not execute a resynchronization process of radio frames; ,

Including

The dependent synchronization base station is

A second interference measurement step for measuring interference by neighboring base stations when a predetermined resynchronization time is reached;

If there is interference from a neighboring base station, if the neighboring base station of the interference source contains at least one absolute synchronization base station, radio frame resynchronization processing is performed, while interference from neighboring base stations exists. The second resynchronization process execution determining step that does not execute the resynchronization process of the radio frame when there is interference by the neighboring base station and all of the neighboring base stations that are the interference are subordinate synchronization base stations,

A wireless communication method comprising:

[6] If the base station (corresponding to the absolute synchronization base station and the dependent synchronization base station) can further be a handover destination, the base station A handover feasibility judgment step for transmitting a signal indicating that it is possible (handover possible signal);

The wireless communication method according to claim 5, further comprising:

[7] Adjust radio frame phase based on GPS (Global Positioning System) signal In the base station that operates as an absolute synchronization base station that performs synchronization processing)

If there is interference from neighboring base stations, the first phase difference between the GPS signal and the radio frame when the previous resynchronization process was performed, and the second position between the current GPS signal and the radio frame. If the difference between the phase difference and the difference is equal to or greater than a specific threshold value, the radio frame resynchronization

On the other hand, if there is no interference from neighboring base stations, or there is interference from neighboring base stations and the difference between the first phase difference and the second phase difference is less than a specific threshold, A base station that does not execute frame resynchronization processing.

Adjust the phase of the radio frame based on the GPS (Global Positioning System) signal.Adjust the phase of the radio frame of your station so that it matches the phase of the radio frame after adjustment at the absolute synchronization base station (resynchronization processing) In a base station operating as a subordinate synchronized base station,

If there is interference from a neighboring base station, if there is at least one absolute synchronization base station in the neighboring base station of the interference source, the radio frame resynchronization process is executed.

On the other hand, if there is no interference from neighboring base stations, or if there is interference from neighboring base stations and all of the neighboring neighboring base stations are subordinate synchronization base stations, radio frame resynchronization processing is not executed. Feature base station.