JP2002315046A - Communication device - Google Patents

Abstract

(57) [Summary] [Problem] Even if there is a request to increase the transmission speed,
If there were no free channels, it could not be raised. SOLUTION: During communication (201), when there is a request to increase the data transmission rate (202), if there is no available channel for increasing the transmission rate by increasing the number of communication channels at the currently used carrier frequency (207). ), A frequency handover is performed to a carrier frequency having sufficient free channels for increasing the number of channels to be used and increasing the transmission speed (211).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device for performing a frequency handover.

[0002]

2. Description of the Related Art The configuration of a conventional mobile communication system is shown in FIG.
Shown in A base station (301) of the mobile communication system forms a communicable wireless zone.

FIG. 3 shows a situation where a plurality of mobile stations such as a mobile communication telephone (302), a mobile communication videophone (303), and a mobile communication information terminal (304) exist in the wireless zone. Is shown.

FIG. 4 shows a basic configuration of a terminal device of a mobile communication system.

[0005] The base station (301) includes an RF unit (401) for performing transmission / reception processing of a radio link, a modulation / demodulation unit (402) for performing digital modulation / demodulation processing, a channel codec unit (403) for performing codec-decoding of data, and the public. Or a digital network interface unit (404) for connecting to a private digital network,
It is composed of a base station control unit (405) that controls these controls.

[0006] The mobile station (mobile communication telephone 302, mobile communication videophone 303, mobile communication information terminal 304) includes an RF unit (406) for performing transmission / reception processing of a radio link and a modulation / demodulation unit (for digital modulation / demodulation processing). 407), a channel codec section (408) for decoding and decoding data, an input / output section (409) for controlling a microphone, a speaker, an image pickup section, an image monitor, and the like, and a mobile station control section (410) for controlling these overall controls , Etc.

In mobile communication systems, the ratio of data communication for transmitting and receiving data other than voice calls has been increasing year by year. In data communication, unlike voice calls,
The amount of data that must be transferred during communication is not constant with time, but changes dynamically.

[0008] In the conventional mobile communication system, when the amount of data to be transmitted is increased, the transmission speed is increased to cope with the increase. Further, when a transmission speed higher than the maximum transmission speed of the currently used channel is required, a process of increasing the transmission speed over the entire communication path by adding a channel is performed.

[0009] However, in order to add a channel to increase the transmission speed, the base station must have a surplus channel, and the channel is not surplus because another user is using the channel. Sometimes it is not possible to add channels or secure the required number of channels and must endure at low transmission rates.

In a mobile communication system using a CDMA (code division multiple access) communication system, channels are distinguished by spreading codes, and the number of channels that can be accommodated at a certain carrier frequency is limited. However, there may be extra channels at other carrier frequency. As described above, when there is an extra channel at another carrier frequency, the transmission rate can be increased by performing frequency handover.

Japanese Patent Application Laid-Open No. 11-341555 describes a conventional technique relating to frequency handover. This prior art describes a method of selecting a frequency between a base station and a mobile station when base stations in a plurality of systems exist in the same service area, and may affect other mobile communication systems. I try not to give.

[0012]

In a code division multiple access system (CDMA), each communication channel is identified by changing a code to be assigned. In data communications, etc., when there is a request to increase the transmission rate beyond that of the currently communicating channel due to an increase in the amount of data to be transmitted, received, or transmitted / received, the transmission rate is increased by newly increasing the channel. Was raised.

[0013] However, there is a case where there is not enough free channel for newly increasing a channel in order to increase the transmission speed, for example, because another mobile communication user is using another channel. If there is no empty channel, the transmission rate cannot be increased as requested.

[0014]

SUMMARY OF THE INVENTION According to the present invention, even if there are not enough free channels to increase the transmission rate at the currently used carrier frequency, there is a possibility that there will be free channels if the carrier frequency is changed. The transmission speed cannot be increased any more on the channel currently communicating, but if the transmission speed can be increased by increasing the channel by changing the carrier frequency, the carrier frequency with enough available channels to increase the transmission speed must be increased. If there is, the frequency handover is performed to the carrier frequency, and the communication is continued by increasing the transmission speed by increasing the number of channels used.

The mobile station may be instructed by the communicating base station to inform it of a carrier frequency having a sufficient number of channels, or may be periodically provided from the base station by a carrier frequency having a sufficient number of channels, or may be provided with the number of available channels of all carrier frequencies. I will tell you.

If the base station determines whether or not to perform frequency handover, it is sufficient to tell the mobile station to which carrier frequency to move only when performing frequency handover.

The determination as to whether to increase the transmission rate, whether to perform frequency handover, and when performing frequency handover, which carrier frequency to use may be determined by the mobile station or the base station.

[0018]

FIG. 1 shows the configuration of a mobile communication system embodying the present invention.

The base station includes an RF unit (101) for performing transmission / reception processing of a radio link, a modulation / demodulation unit (102) for performing digital modulation / demodulation processing, etc., a channel codec unit (103) for encoding / decoding data, a public or private digital A digital network interface unit (104) for connecting to a network, a communication channel grasping unit (105) for keeping track of the number of channels used at each carrier frequency, and a base station control unit (106) for controlling these overall operations And a memory (106M) storing a program of the base station control unit (106).

The mobile station includes an RF unit (107) for performing transmission / reception processing of a wireless link, a modulation / demodulation unit (108) for performing digital modulation / demodulation processing, etc., a channel codec unit (109) for codec-decoding data, a microphone / speaker / An input / output processing unit (110) for controlling an imaging unit, an image monitor, etc., a mobile station control for controlling the entire mobile station device, deciding whether to perform a handover based on communication quality and moving speed, or asking a base station for a judgment. (111M), a memory (111M) storing a program of the mobile station controller (111), and the like.

In the embodiment of the present invention, when there is a request to increase the transmission rate in the communication currently being communicated, the transmission rate is increased to the requested transmission rate because there is no channel that has a surplus carrier wave frequency. If this is not possible, if there are enough free channels on other carrier frequencies, the transmission rate is increased to the requested rate by performing a frequency handover to the carrier frequency.

The above processing will be described with reference to the flowchart of FIG. The flowchart of FIG. 2 represents a program of the mobile station control unit 111 stored in the memory 111M. The mobile station control unit 111 is a computer, and the memory 111M
The program represented by the flowchart of FIG.
This is a storage medium that is readable by the mobile station control unit 106. Hereinafter, processing executed by the mobile station based on the control of the mobile station control unit 111 will be described with reference to the flowchart of FIG.

During the communication (201), when a request to increase the transmission speed is issued (202) due to an increase in the amount of data to be transmitted or received, the mobile station uses the current communication. When the transmission rate required by the number of channels is sufficiently increased (203), the transmission rate is increased to continue the communication (204), and the processing for increasing the transmission rate is terminated (213).

When it is desired to increase the transmission data rate input from the imaging unit to the input / output unit processing unit 110 during transmission of imaging data from the imaging unit, or during reception of image data monitored by an image monitor, For example, if you want to increase the reception data rate output from the input / output
The input / output processing unit 110 requests the mobile station control unit 111 to increase the transmission rate during communication.

When the transmission rate required by the number of channels currently used for communication cannot be sufficiently increased (20
3) It is determined whether the number of currently used channels is smaller than the maximum number N of available channels determined from system conditions or the like (205). The number N of channels may be a value arbitrarily set. If the number of currently used channels is larger than the number N of the channels (205), the communication is continued with the transmission speed unchanged (206), and the process of increasing the transmission speed ends (213). That is, when the number of currently used channels is N or more, the processing for increasing the transmission speed is not performed.

When the number of currently used channels is equal to or less than the number of channels N (205), there is still room for increasing the number of channels and increasing the transmission speed. It is checked whether there is a sufficient free channel between the base station and the base station (207).
If there are enough vacant channels to obtain the requested transmission rate, communication is continued by increasing the transmission rate by increasing the number of channels at the currently used carrier frequency (208), and increasing the transmission rate. The raising process ends (213).

When there is not enough free channel with the base station connected to the base station connected to the currently used carrier frequency (207), the carrier frequency between the base station connected to the base station and the base station connected to the base station is not used. If there are many free channels at other carrier frequencies (209), a frequency handover is performed to the carrier frequency with the most free channels (21).
1) The communication is continued by increasing the transmission rate by increasing the number of channels to be used, and the processing for increasing the transmission rate is terminated (213).

That is, when there is a request to increase the data transmission rate during communication, if the number of communication channels is increased and there is no available channel for increasing the transmission rate at the currently used carrier frequency, the number of channels to be used is increased. Frequency handover to a carrier frequency with sufficient free channels to increase the transmission rate. When performing the frequency handover, the mobile station control unit 111 changes the carrier frequency of the RF unit 107.

Further, the frequency handover to another carrier frequency is performed when the required transmission rate cannot be realized with the number of channels of the carrier currently used (207 is N).
Do.

Further, in this frequency handover, the frequency handover is performed to a carrier frequency having a larger number of vacant channels than the number of vacant channels at the currently used carrier frequency, for example, a carrier having the largest number of vacant channels at all carrier frequencies. I do.

The number of vacant channels of the carrier frequency not currently used is notified from the base station to the mobile station. The mobile station includes an RF unit 107, a modem unit 108, a channel codec unit 10
From the signal received via 9, detect the number of free channels. The mobile station determines the carrier frequency to which the mobile station is to be shifted based on the number of unused channels of the carrier frequency which is not currently used and notified from the base station.

The mobile station is periodically notified of the number of idle channels at each carrier frequency from the base station.

In another embodiment, when there is a request to increase the transmission rate, the mobile station requests the base station to notify the number of vacant channels in each carrier frequency prior to the determination in 209.

In still another embodiment, prior to the determination in 209, the base station is requested to notify the carrier frequency having the largest number of available channels.

The communication channel number grasping section 105 grasps the number of used channels and the number of unused channels at each carrier frequency. Communication channel number grasping unit 105
Detects the channel used by the base station for communication with a plurality of mobile stations, and grasps the number of used channels and the number of free channels. The base station notifies the mobile station of the number of vacant channels at each carrier frequency recognized by the communication channel number determination unit 105 periodically or in response to a request from the mobile station.

If the number of vacant channels of the other carrier frequencies is equal to or less than the currently used carrier frequency (209), the communication is continued at the currently used carrier frequency by increasing the transmission speed as much as possible, and Is completed (213).

In the above description, the mode in which the mobile station performs the processing of FIG. 2 has been described.

In another embodiment, the base station performs the processing of FIG.

That is, in response to a request to increase the transmission rate, the base station determines whether or not to perform frequency handover based on the number of currently used channels. Is determined. The mobile station requests the base station to increase the transmission rate.

In this embodiment, the flowchart of FIG.
4 shows a program of the base station control unit 106 stored in the memory 106M. The mobile station control unit 106 is a computer,
The memory 106M is a storage medium that stores the program represented by the flowchart in FIG.

In this embodiment, at 207, it is checked whether there is a sufficient free channel with the connected mobile station at the currently used carrier frequency.

If there is not enough available channels between the mobile station and the mobile station connected at the currently used carrier frequency at 207, then the mobile station at present uses the mobile station with the connected mobile station at 209. A check is made to see if there are more vacant channels on the other carrier frequency than the present carrier frequency.

Also in this embodiment, the number of vacant channels at each carrier frequency is determined by the communication channel number grasping unit 10.
5 have figured out. The base station control unit 106 detects the number of empty channels recognized by the communication channel number determination unit 105.

[0044]

When there is a request to increase the transmission rate, if there is no vacant channel at the carrier frequency currently being used, but there are enough vacant channels at other carrier frequencies, there is a sufficient vacant channel. By performing the frequency handover to the carrier frequency that is being performed, it is possible to increase the transmission speed to a level that could not be increased at the carrier frequency before the handover was performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a mobile communication system device according to the present invention.

FIG. 2 is a flowchart of an embodiment of the present invention.

FIG. 3 is a configuration example of a mobile communication system.

FIG. 4 is a basic configuration diagram of a mobile communication system device.

[Explanation of symbols]

 107 RF unit 111 Mobile station control unit 111M Memory

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference)

Claims (16)

[Claims] 1. detecting means for detecting the number of vacant channels;
If there is a request to increase the data transmission rate during communication and there are no available channels for increasing the transmission rate by increasing the number of communication channels at the current carrier frequency, increase the transmission rate by increasing the number of channels used. A frequency handover means for performing a frequency handover to a carrier frequency having sufficient available channels for the communication. 2. The frequency handover means, when there is a request to increase the data transmission rate, judges whether or not the requested transmission rate is realized by the number of channels of the carrier currently used, and Performing frequency handover to another carrier frequency.
The communication device according to claim 1. 3. The frequency handover unit according to claim 1, wherein the frequency handover means performs a frequency handover to a carrier frequency having a larger number of vacant channels than the number of vacant channels in the currently used carrier frequency.
Or the communication device according to 2. 4. The communication apparatus according to claim 1, wherein the frequency handover means performs a frequency handover to a carrier frequency having the largest number of available channels in all carrier frequencies. 5. The communication apparatus according to claim 1, wherein the frequency handover unit does not perform a process for increasing a transmission rate when the number of currently used channels is N or more. 6. The communication apparatus according to claim 1, wherein the frequency handover means determines whether to perform frequency handover based on the number of currently used channels when there is a request to increase the transmission rate. . 7. The frequency handover unit according to claim 1, wherein the frequency handover means determines a carrier frequency to which the frequency shifts based on the number of unused channels of the currently unused carrier frequency notified from the base station. Communication device. 8. The communication apparatus according to claim 6, wherein the frequency handover unit receives a notification of the number of available channels at each carrier frequency from the base station at regular intervals. 9. The communication apparatus according to claim 6, wherein the frequency handover unit requests the base station to notify the number of available channels in each carrier frequency. 10. The communication apparatus according to claim 6, wherein the frequency handover unit requests the base station to notify a carrier frequency having the largest number of available channels. 11. The frequency handover means determines whether or not to perform a frequency handover based on the number of currently used channels in response to a request to increase the transmission rate on the base station side. 2. The communication apparatus according to claim 1, wherein a destination carrier frequency is determined based on the number of available channels. 12. When there is a request to increase the data transmission rate during communication, the number of channels to be used is increased if the number of communication channels is not increased and a vacant channel for increasing the transmission rate is not at the currently used carrier frequency. Frequency handover method for performing a frequency handover to a carrier frequency having sufficient free channels to increase the transmission speed. 13. When there is a request to increase the data transmission rate during communication, if the number of communication channels is increased and there is no available channel for increasing the transmission rate at the currently used carrier frequency, the number of channels to be used is increased. Or a storage medium storing the program for performing a frequency handover to a carrier frequency having a sufficient free channel to increase the transmission speed. 14. The communication means, if the number of vacant channels other than the used carrier frequency during communication is larger than the number of vacant channels of the used carrier frequency, performs frequency handover to a carrier frequency having more vacant channels, A communication device having communication control means for increasing the number of channels used. 15. During communication, if the number of vacant channels other than the used carrier frequency is larger than the number of vacant channels of the used carrier frequency, frequency handover is performed to the carrier frequency having more vacant channels, and the number of used channels is increased. A communication method characterized by increasing the number of communications. 16. During communication, if the number of vacant channels other than the used carrier frequency is larger than the number of vacant channels of the used carrier frequency, frequency handover is performed to the carrier frequency having more vacant channels, and the number of used channels is increased. Or a storage medium storing the program.