JP4880342B2 - Wireless base station, wireless communication terminal and communication method - Google Patents

Description

  The present invention relates to a radio base station, a radio communication terminal, and a communication method that can change a modulation parameter of a radio communication path set by using a communication channel defined by at least a frequency or a time slot to be used.

  Conventionally, in a wireless communication system such as a personal handyphone system (PHS), a setting is made between a wireless communication terminal (hereinafter abbreviated as “PS” as appropriate) and a wireless base station (hereinafter abbreviated as “CS” as appropriate). A so-called adaptive modulation scheme has been introduced in which the modulation parameter of a wireless channel that has been changed is adaptively changed according to communication quality (for example, Patent Document 1).

In a wireless communication system in which such an adaptive modulation method is introduced, the modulation parameters are sequentially changed to a modulation parameter that is resistant to deterioration in communication quality although the transmission rate is low, depending on the state of deterioration in communication quality of the wireless communication path. For example, when the communication quality deteriorates, the modulation parameter is changed from 16QAM to π / 4 shift QPSK.
Japanese Patent Laying-Open No. 2005-51684 (page 8, FIG. 4)

  However, the conventional adaptive modulation system described above has the following problems. That is, when the communication quality of the wireless communication path deteriorates, the transmission parameter is uniformly changed to a modulation parameter with a low transmission rate. Therefore, for example, even when there is a vacant communication channel (TCH) and there is a possibility that communication can be maintained without lowering the transmission rate by switching the wireless communication path to the vacant communication channel, the transmission rate is There was a problem of being lowered.

  Therefore, the present invention has been made in view of such a situation, and in a wireless communication system in which an adaptive modulation scheme is introduced, while avoiding a decrease in transmission rate as much as possible, the wireless communication path An object of the present invention is to provide a radio base station, a radio communication terminal, and a communication method capable of maintaining communication quality.

In order to solve the problems described above, the present invention has the following features. First, the first feature of the present invention is that wireless communication set up with a wireless communication terminal (PS200) using a communication channel (for example, TCH # 1) defined by at least a frequency or time slot to be used. modulation parameters of the road (wireless communication path WL) (e.g., 16QAM) a radio base station (CS100) which can be changed, said a receiving communication quality of the communication channel currently used by the wireless communication channel free communication channel of the wireless communication channel (e.g., TCH # 4) communication quality acquiring unit that acquires the receiving communication quality (the radio signal processing unit 103), in said wireless communication path acquired by the communication quality acquisition unit based on the communication channel receiving communication quality currently used, the modulation parameters of the transmission rate is lower low-rate modulation parameter (e.g., 8PSK If the received communication quality of the empty communication channel exceeds a predetermined threshold, it is determined to change to the empty communication channel, and the received communication quality of the empty communication channel is If the predetermined threshold is not exceeded, a communication control unit (radio control unit 105) that determines to change the modulation parameter to the low rate modulation parameter, and a change to the low rate modulation parameter by the communication control unit, Alternatively, the present invention includes a communication processing unit (radio control unit 105) that changes the modulation parameter or the communication channel based on the decision to change to the free communication channel.

  According to such a radio base station, based on the deterioration state of the received communication quality acquired by the communication quality acquisition unit, the modulation parameter is changed to a low rate modulation parameter with a low transmission rate, or the communication channel is different. It is determined whether to change to a channel.

  For this reason, even when the received communication quality deteriorates, if there is an unused communication channel and communication can be maintained without lowering the transmission rate by switching the wireless communication path to the unused communication channel, The communication channel can be changed to an empty communication channel.

  In other words, if communication can be maintained without reducing the transmission rate by switching to a different communication channel, the transmission rate of the wireless communication path may be reduced by changing to a low-rate modulation parameter with a low transmission rate. Can be avoided.

A second feature of the present invention relates to the first feature of the present invention, wherein the communication quality acquisition unit is configured to receive a desired wave reception level in the communication channel and a ratio of the desired wave and unnecessary wave reception levels (D / U ratio), and the communication control unit determines the change to the empty communication channel based on the reception level of the desired wave and the ratio of the reception level of the desired wave and the unnecessary wave. And

  A third feature of the present invention relates to the first feature of the present invention, wherein the communication quality acquisition unit acquires a fading speed of a desired wave in the communication channel, and the communication control unit performs fading of the desired wave. The gist is to determine the change to the different communication channel when the speed exceeds a predetermined threshold.

According to a fourth aspect of the present invention, there is provided a radio base capable of changing a modulation parameter of a radio channel set with a radio communication terminal using a communication channel defined by at least a frequency or a time slot to be used. A change request acquisition unit that acquires a change request for a downlink modulation parameter from the wireless communication terminal, and a change request for the downlink modulation parameter is acquired by the change request acquisition unit, A communication quality acquisition unit that acquires the reception communication quality of a communication channel that is currently used in the wireless communication path, and the downlink direction based on the deterioration state of the reception communication quality acquired by the communication quality acquisition unit different passing or transmission rate modulation parameter is changed to a lower low-rate modulation parameters, or the communication channel in the wireless communication channel A communication control unit that determines whether to change to a channel, and the downlink modulation parameter or the communication based on the change to the low-rate modulation parameter by the communication control unit or the determination to change to the different communication channel And a communication processing unit for changing a channel.

A fifth feature of the present invention is that a wireless communication channel (CS100) established with a wireless base station (CS100) using a communication channel (for example, TCH # 1) defined by at least a frequency or a time slot to be used. A wireless communication terminal (PS200) capable of changing a modulation parameter (for example, 16QAM) of a wireless communication channel WL), wherein the received communication quality of the communication channel currently used in the wireless communication channel and the wireless communication A communication quality acquisition unit (radio signal processing unit 203) that acquires the received communication quality of an empty communication channel (for example, TCH # 1) in the path, and is currently used in the radio communication path acquired by the communication quality acquisition unit based on the received communication quality of the communication channel being the modulation parameters transmission rate is low low-rate modulation parameter (e.g., 8 ps If the received communication quality of the empty communication channel exceeds a predetermined threshold, the change to the empty communication channel is determined, and the received communication quality of the empty communication channel is determined. Is not exceeding a predetermined threshold, a communication control unit (control unit 205) that determines to change the modulation parameter to the low-rate modulation parameter, and a change to the low-rate modulation parameter by the communication control unit, Alternatively, the present invention includes a communication processing unit (control unit 205) that changes the modulation parameter or the communication channel based on the determination of the change to the free communication channel.

  A sixth feature of the present invention relates to the fifth feature of the present invention, wherein the communication quality acquisition unit is configured to receive a desired wave reception level in the communication channel and a ratio (D / U ratio), and the communication control unit determines to change to the different communication channel based on the reception level of the desired wave and the ratio of the reception level of the desired wave and the unnecessary wave. And

  A seventh feature of the present invention relates to the fifth feature of the present invention, wherein the communication quality acquisition unit acquires a fading speed of a desired wave in the communication channel, and the communication control unit performs fading of the desired wave. The gist is to determine the change to the different communication channel when the speed exceeds a predetermined threshold.

An eighth feature of the present invention is that a modulation parameter of a wireless communication path set between a wireless communication terminal and a wireless base station is changed using a communication channel defined by at least a frequency or a time slot to be used. A communication method that is capable of obtaining a received communication quality of a communication channel currently used in the wireless communication channel and a received communication quality of an empty communication channel in the wireless communication channel; and the communication quality acquisition unit If it is determined that the modulation parameter needs to be changed to a low-rate modulation parameter with a low transmission rate based on the received communication quality of the communication channel currently used in the wireless communication channel acquired by If the received communication quality of the empty communication channel exceeds a predetermined threshold, the change to the empty communication channel is determined, and the empty communication channel is determined. If the received communication quality of the channel does not exceed a predetermined threshold, determining to change the modulation parameter to the low rate modulation parameter, and changing to the low rate modulation parameter in the determining step, or And a step of changing the modulation parameter or the communication channel based on the decision to change to an empty communication channel.

A ninth feature of the present invention is that a modulation parameter of a wireless communication path set between a wireless communication terminal and a wireless base station is changed using a communication channel defined by at least a frequency to be used or a time slot. A downlink modulation parameter change request from the wireless communication terminal, and when the downlink modulation parameter change request is acquired in the acquiring step, A step of acquiring a reception communication quality of a communication channel currently used in a wireless communication channel , and a transmission rate of the modulation parameter in the downlink direction based on the deterioration state of the reception communication quality acquired in the step of acquiring different in the radio communication channel to change to a lower low-rate modulation parameters, or the communication channel The downlink modulation parameter or the communication channel based on the step of determining whether to change to a communication channel, and the change to the low-rate modulation parameter in the determining step, or the change to the different communication channel And a step of changing.

  According to the features of the present invention, in a wireless communication system in which an adaptive modulation scheme is introduced, a wireless base station capable of maintaining the communication quality of the wireless communication path while avoiding a decrease in transmission rate as much as possible A wireless communication terminal and a communication method can be provided.

  Next, an embodiment of the present invention will be described. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(Overall schematic configuration of wireless communication system)
FIG. 1 is an overall schematic configuration diagram of a wireless communication system 10 according to the present embodiment. 1, the radio communication system 10 includes a radio base station 100 (hereinafter referred to as CS 100) and a radio communication terminal 200 (hereinafter referred to as PS 200) Note that the number of CSs and PSs included in the radio communication system 10 Is not limited to the number shown in FIG.

  The wireless communication system 10 is a wireless communication system compliant with a personal handyphone system (PHS) using a TDMA / TDD system, and in this embodiment, wireless communication is performed using a frequency of 1.9 GHz band.

  Further, in the wireless communication system 10, there is a so-called adaptive modulation method that can change the modulation parameter of the wireless communication channel WL set between the CS 100 and the PS 200 using a communication channel (hereinafter, abbreviated as TCH as appropriate). Has been introduced. For example, when the communication quality of the wireless communication path WL deteriorates, the modulation parameter is changed from 16QAM to 8PSK.

(Function block configuration)
Next, a functional block configuration of the wireless communication system 10 will be described. FIG. 2 is a functional block configuration diagram of the CS 100. FIG. 3 is a functional block configuration diagram of the PS 200. Hereinafter, portions related to the present invention will be mainly described. Therefore, it should be noted that the CS 100 and the PS 200 may include blocks (not shown) or omitted blocks (for example, a display unit in the PS 200) that are essential for realizing the function of the device.

(1) Radio Base Station As shown in FIG. 2, the CS 100 includes a radio unit 101, a radio signal processing unit 103, a radio control unit 105, a central control unit 107, a line control unit 109, and a power supply unit 111.

  The wireless unit 101 includes an antenna 101a and includes a transmitter and a receiver that use a radio frequency of 1.9 GHz band.

  The radio signal processing unit 103 is connected to the radio unit 101 and the central control unit 107. The radio signal processing unit 103 is also connected to the radio control unit 105.

  The radio signal processing unit 103 has a DSP (digital signal processor), and based on control by the radio control unit 105, digital modulation processing of a signal output by the central control unit 107 and a signal output by the radio unit 101 The digital demodulation processing is executed. Further, the radio signal processing unit 103 executes multiplexing (and demultiplexing) processing of the signal.

  In the present embodiment, the wireless signal processing unit 103 acquires the received communication quality of the wireless communication path WL. In the present embodiment, the wireless signal processing unit 103 constitutes a communication quality acquisition unit.

  Specifically, the radio signal processing unit 103 can acquire the reception level of the desired wave (D wave) in TCH and the ratio (D / U ratio) of the reception level of the desired wave and unnecessary wave (U wave). it can. Furthermore, the radio signal processing unit 103 can acquire a fading speed of a desired wave (D wave) in TCH.

  The radio signal processing unit 103 can also acquire the received communication quality (for example, the received power level of the frequency corresponding to the empty communication channel) in the empty communication channel (empty TCH).

  Here, FIG. 7 shows an example of the TCH configuration. As shown in FIG. 7, it is configured by four communication channels TCH # 1 to TCH # 4. In this embodiment, the communication channel is defined by a frequency and a time slot. Note that the communication channel may be defined by either frequency or time slot.

  The radio control unit 105 controls the radio signal processing unit 103 in accordance with an instruction from the central control unit 107. In addition, the wireless control unit 105 executes processing according to the wireless communication protocol used in the wireless unit 101 and the wireless signal processing unit 103.

  Further, in the present embodiment, the radio control unit 105 changes the modulation parameter to a low-rate modulation parameter with a low transmission rate based on the degradation state of the received communication quality acquired by the radio signal processing unit 103 or performs communication. It can be decided whether to change the channel to a different communication channel. In the present embodiment, the wireless control unit 105 constitutes a communication control unit.

  The radio control unit 105 determines to change to a different communication channel based on the reception level of the D wave acquired by the radio signal processing unit 103 and the D / U ratio. For example, when the D wave reception level is higher than a predetermined threshold and the D / U ratio is lower than the predetermined threshold, the radio control unit 105 determines that the received communication quality is deteriorated due to interference.

  When it is determined that the reception communication quality is deteriorated due to interference, the radio control unit 105 determines to change to a different communication channel in order to avoid the interference. For example, when the wireless communication path WL is set using TCH # 1 (see FIG. 7), the wireless control unit 105 switches to TCH # 4, which is a free communication channel that is not used for communication.

  In addition, the radio control unit 105 can determine to change to a different communication channel when the fading speed of the D wave exceeds a predetermined threshold.

  Furthermore, when the received communication quality of a free communication channel (for example, TCH # 4) exceeds a predetermined threshold, radio control section 105 determines to change to the free communication channel. That is, when the received communication quality of the free communication channel is good, the radio control unit 105 determines to change to the free communication channel.

  Radio control section 105 changes the modulation parameter to a low-rate modulation parameter with a low transmission rate when the received communication quality deteriorates below a predetermined threshold and does not satisfy the above-described TCH change condition. For example, the radio control unit 105 changes from 16QAM to 8PSK.

  Here, FIG. 8 shows an example of a modulation parameter used in the present embodiment. As shown in FIG. 8, 16QAM, 8PSK, π / 4 shift QPSK, BPSK, or the like is used. In the modulation parameters shown in FIG. 8, the transmission rate is the highest at 16QAM and the lowest at BPSK.

  The radio control unit 105 changes the communication channel based on the decision to change to a different communication channel. Further, the radio control unit 105 changes the modulation parameter based on the decision to change to the low rate modulation parameter. In the present embodiment, the wireless control unit 105 constitutes a communication processing unit.

  Further, the radio control unit 105 can change the modulation parameter based on the modulation parameter switching request (MOD switching request) received from the PS 200. Furthermore, the radio control unit 105 can also transmit a modulation parameter switching instruction (MOD switching instruction) to the PS 200.

  The central control unit 107 controls each functional block constituting the CS 100. In addition, the central control unit 107 executes setting and release (exchange control) of a speech path set between the radio signal processing unit 103 and the line control unit 109.

  The line control unit 109 connects an ISDN line (specifically, an I ′ line), and executes processing according to a protocol related to ISDN.

  The power supply unit 111 supplies necessary power to each functional block constituting the CS 100.

(2) Radio Communication Terminal As shown in FIG. 3, the PS 200 includes a radio unit 201, a radio signal processing unit 203, a control unit 205, an audio signal processing unit 207, a microphone 209, a speaker 211, and a power supply unit 213. The PS 200 can change the modulation parameter and the communication channel based on the received communication quality, similarly to the CS 100 described above. Hereinafter, the description of the same parts as the CS 100 described above will be omitted as appropriate.

  The wireless unit 201 includes an antenna 201a and is configured by a transmitter and a receiver that use a radio frequency of 1.9 GHz band.

  The radio signal processing unit 203 is connected to the radio unit 201 and the audio signal processing unit 207. The radio signal processing unit 203 is also connected to the control unit 205.

  The radio signal processing unit 203 includes a DSP (digital signal processor), and based on control by the control unit 205, digital modulation processing of the signal output by the audio signal processing unit 207 and signal output by the radio unit 201 The digital demodulation processing is executed.

  In addition, the wireless signal processing unit 203 acquires the received communication quality of the wireless communication path WL. In the present embodiment, the wireless signal processing unit 203 constitutes a communication quality acquisition unit.

  Similarly to the wireless signal processing unit 103, the wireless signal processing unit 203 determines the reception level of the desired wave (D wave) and the ratio of the reception level of the desired wave and unnecessary wave (U wave) (D / U ratio) in the TCH. Can be acquired. Furthermore, the radio signal processing unit 203 can acquire a fading speed of a desired wave (D wave) in TCH.

  Further, the radio signal processing unit 203 can also acquire the received communication quality in the empty communication channel (empty TCH).

  The control unit 205 controls the wireless signal processing unit 203 and the audio signal processing unit 207. In particular, in the present embodiment, the control unit 205 changes the modulation parameter to a low-rate modulation parameter with a low transmission rate based on the degradation state of the received communication quality acquired by the wireless signal processing unit 203 or the communication channel. To change to a different communication channel. In the present embodiment, the control unit 205 constitutes a communication control unit.

  The control unit 205 determines a change to a different communication channel based on the reception level of the D wave acquired by the wireless signal processing unit 103 and the D / U ratio.

  In addition, the control unit 205 can determine to change to a different communication channel when the fading speed of the D wave exceeds a predetermined threshold.

  Furthermore, when the received communication quality of the free communication channel (for example, TCH # 4) exceeds a predetermined threshold, the control unit 205 determines to change to the free communication channel. That is, when the received communication quality of the free communication channel is good, the control unit 205 determines to change to the free communication channel.

  The control unit 205 changes the modulation parameter to a low-rate modulation parameter with a low transmission rate when the received communication quality deteriorates below a predetermined threshold and does not satisfy the above TCH changing condition.

  The control unit 205 changes the communication channel based on the decision to change to a different communication channel. Further, the control unit 205 changes the modulation parameter based on the decision to change to the low rate modulation parameter. In the present embodiment, the control unit 205 constitutes a communication processing unit.

  Further, the control unit 205 can change the modulation parameter based on the MOD switching instruction received from the CS 100. Further, the control unit 205 can transmit a MOD switching request to the CS 100.

  The audio signal processing unit 207 executes digital conversion processing of the audio signal acquired by the microphone 209 and the audio signal output to the speaker 211.

  The power supply unit 213 supplies necessary power to each functional block constituting the PS 200. In the present embodiment, the power supply unit 213 is configured by a small battery.

(Operation of wireless communication system)
Next, the operation of the wireless communication system 10 will be described. Specifically, (1) Modulation parameter or communication channel change flow in CS100, (2) Modulation parameter or communication channel change sequence based on degradation of uplink reception communication quality, (3) Downlink reception communication quality A modulation parameter or a communication channel change sequence based on degradation of the communication will be described.

(1) Modulation Parameter or Communication Channel Change Flow FIG. 4 shows a modulation parameter or communication channel change flow in the CS 100.

  In step S10, the CS 100 executes communication with the PS 200 through the wireless communication path WL that can change the modulation parameter. Here, it is assumed that the wireless communication path WL is set using TCH # 1 (see FIG. 7).

  In step S20, the CS 100 determines whether or not a MOD switching request for requesting switching of a modulation parameter is received from the PS 200.

  When the MOD switching request is not received (NO in step S20), in step S30, the CS 100 acquires the received communication quality. Specifically, the CS 100 can acquire the reception level of the D wave, the D / U ratio, and the fading speed of the D wave as the received communication quality. On the other hand, when the MOD switching request is received (YES in step S20), the CS 100 executes the process in step S50.

  In step S40, the CS 100 determines whether to change the modulation parameter based on the acquired reception quality.

  When changing the modulation parameter (YES in step S40), in step S50, the CS 100 determines whether to upgrade the modulation parameter, that is, to change to a modulation parameter with a high transmission rate. Specifically, the CS 100 determines to change to a modulation parameter with a high transmission rate when the received communication quality acquired in step S30 is good. On the other hand, when the modulation parameter is not changed (NO in step S40), the CS 100 repeats the processing from step S10.

  When the modulation parameter is not upgraded (NO in step S50), in step S60, the CS 100 measures the received power level of the frequency corresponding to the free communication channel of the free communication channel (for example, TCH # 4).

  In step S70, the CS 100 executes modulation parameter change or switching to an empty communication channel. Specifically, as described above, the CS 100 switches the TCH when the TCH change condition is satisfied. On the other hand, when the TCH changing condition is not satisfied, the CS 100 changes the modulation parameter to a modulation parameter with a low transmission rate. For example, the CS 100 changes from 16QAM to 8PSK.

  When executing TCH switching (“TCH” in step S70), in step S80, the CS 100 executes a TCH switching sequence.

  On the other hand, when the modulation parameter is upgraded (YES in step S50), or when the modulation parameter is changed to a modulation parameter with a low transmission rate ("MOD switching" in step S70), in step S90, the CS 100 performs MOD switching for changing the modulation parameter. Run the sequence.

(2) Modulation parameter or communication channel change sequence (upward direction)
FIG. 5 shows a change sequence of a modulation parameter or a communication channel based on degradation of reception communication quality in the uplink direction. As shown in FIG. 5, in step S110, the CS 100 and the PS 200 perform communication through the wireless communication path WL. Here, it is assumed that the wireless communication path WL is set using TCH # 1 (see FIG. 7). It is assumed that 16QAM is set in the wireless communication path WL.

  In step S120, the CS 100 acquires the uplink received communication quality. In step S130, CS 100 determines whether or not the current modulation parameter (16QAM) can be maintained based on the acquired received communication quality. Here, the CS 100 cannot maintain the current modulation parameter, and determines that a downgrade of the modulation parameter, specifically, a change from 16QAM to 8QPSK is necessary.

  In step S140, the CS 100 measures the received power level of the frequency corresponding to the idle communication channel of the idle communication channel (TCH # 4).

  In step S150, the CS 100 selects to change the modulation parameter or switch to a free communication channel. Specifically, CS 100 selects to change the modulation parameter or switch to a free communication channel based on the received communication quality (for example, reception level) of the free communication channel. Here, it is assumed that the received power level of the frequency corresponding to the available communication channel of the available communication channel is low and the modulation parameter change is selected.

  In step S160, CS 100 transmits, to PS 200, a MOD switching instruction that instructs to change the modulation parameter.

  In step S170, CS 100 and PS 200 execute a MOD switching sequence for changing the modulation parameter.

(3) Modulation parameter or communication channel change sequence (downlink)
FIG. 6 shows a change sequence of a modulation parameter or a communication channel based on degradation of received communication quality in the downlink direction. Hereinafter, the description of the same part as the above-described upward change sequence will be omitted as appropriate.

  As shown in FIG. 6, in step S210, the CS 100 and the PS 200 perform communication through the wireless communication path WL.

  In step S220, the PS 200 acquires the received communication quality in the downlink direction. In step S230, the PS 200 determines whether or not the current modulation parameter (16QAM) can be maintained based on the acquired received communication quality. Here, the PS 200 cannot maintain the current modulation parameter, and determines that a downgrade of the modulation parameter, specifically, a change from 16QAM to 8QPSK is necessary.

  In step S240, the PS 200 transmits a MOD switching request for requesting switching of modulation parameters to the CS 100.

  In step S250, CS 100 measures the received power level of the frequency corresponding to the available communication channel of the available communication channel (TCH # 4) based on the received MOD switching request. In addition, the process of step S260-S280 is the same as the process of step S150-S170 mentioned above.

(Action / Effect)
According to the CS 100, based on the degradation state of the uplink received communication quality acquired by the radio signal processing unit 103, the modulation parameter is changed to a low rate modulation parameter with a low transmission rate, or the communication channel (TCH # 1). ) Is changed to a different communication channel (TCH # 4). Further, the PS 200 performs an operation similar to that of the CS 100 based on the degradation state of the reception communication quality in the uplink direction.

  For this reason, even when the reception communication quality is deteriorated, there is a free communication channel (TCH # 4), and the wireless communication path WL is switched to the free communication channel without lowering the transmission rate of the wireless communication path WL. If communication can be maintained, the communication channel in use can be changed to a free communication channel.

  That is, when communication can be maintained without lowering the transmission rate by switching to a different communication channel, the transmission rate of the wireless communication path WL is lowered by changing to a low-rate modulation parameter with a lower transmission rate. You can avoid that. For this reason, the data throughput between CS100-PS200 improves.

  In the present embodiment, prior to the change of the modulation parameter or the communication channel, the received communication quality in the empty communication channel is acquired, and when the received communication quality of the empty communication channel exceeds a predetermined threshold, the change to the empty communication channel is performed. Is selected. For this reason, it is possible to more reliably maintain the communication quality of the wireless communication path while avoiding a decrease in the transmission rate of the wireless communication path WL.

(Other embodiments)
As described above, the content of the present invention has been disclosed through one embodiment of the present invention. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments will be apparent to those skilled in the art.

  For example, in the above-described embodiment of the present invention, the deterioration state of the received communication quality is determined based on the reception level and D / U ratio of the D wave in the TCH or based on the fading speed of the D wave. The determination of the deterioration state of the received communication quality may be another parameter (for example, RSSI or EVM).

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1 is an overall schematic configuration diagram of a wireless communication system according to an embodiment of the present invention. It is a functional block block diagram of the radio base station which concerns on embodiment of this invention. It is a functional block block diagram of the radio | wireless communication terminal which concerns on embodiment of this invention. It is a change flowchart of a modulation parameter or a communication channel in the radio base station according to the embodiment of the present invention. It is a change sequence diagram of a modulation parameter or a communication channel based on degradation of uplink received communication quality according to an embodiment of the present invention. It is a change sequence diagram of a modulation parameter or a communication channel based on deterioration of downlink received communication quality according to the embodiment of the present invention. It is a figure which shows an example of a structure of the communication channel which concerns on embodiment of this invention. It is a figure which shows an example of the modulation parameter used in the radio | wireless communications system which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Wireless communication system, 100 ... Wireless base station (CS), 101 ... Wireless part, 101a ... Antenna, 103 ... Wireless signal processing part, 105 ... Wireless control part, 107 ... Central control part, 109 ... Line control part, 111 DESCRIPTION OF SYMBOLS ... Power supply part 200 ... Wireless communication terminal (PS) 201 ... Wireless part, 201a ... Antenna, 203 ... Radio signal processing part, 205 ... Control part, 207 ... Audio signal processing part, 209 ... Microphone, 211 ... Speaker, 213 ... Power supply, WL ... Wireless communication path

Claims (9)

A radio base station capable of changing a modulation parameter of a radio channel set up with a radio communication terminal using a communication channel defined by at least a frequency or a time slot to be used,
A communication quality acquisition unit for acquiring the reception communication quality of a communication channel currently used in the wireless communication path and the reception communication quality of an empty communication channel of the wireless communication path ;
Based on the received communication quality of the communication channel currently used in the wireless communication channel acquired by the communication quality acquisition unit, it is determined that the modulation parameter needs to be changed to a low rate modulation parameter with a low transmission rate If the received communication quality of the empty communication channel exceeds a predetermined threshold, the change to the empty communication channel is determined, and if the received communication quality of the empty communication channel does not exceed the predetermined threshold A communication control unit that determines to change the modulation parameter to the low-rate modulation parameter;
A radio base station comprising: a communication processing unit that changes the modulation parameter or the communication channel based on the change to the low rate modulation parameter or the change to the empty communication channel determined by the communication control unit. The communication quality acquisition unit acquires a reception level of a desired wave in the communication channel and a ratio between the reception level of the desired wave and an unnecessary wave,
The radio base station according to claim 1, wherein the communication control unit determines a change to the empty communication channel based on a reception level of the desired wave and a ratio of the reception level of the desired wave and the unnecessary wave. The communication quality acquisition unit acquires a fading speed of a desired wave in the communication channel,
The radio base station according to claim 1, wherein the communication control unit determines to change to the free communication channel when a fading speed of the desired wave exceeds a predetermined threshold. A radio base station capable of changing a modulation parameter of a radio channel set up with a radio communication terminal using a communication channel defined by at least a frequency or a time slot to be used,
A change request acquisition unit for acquiring a change request for a downlink modulation parameter from the wireless communication terminal;
A communication quality acquisition unit that acquires a received communication quality of a communication channel that is currently used in the wireless communication path when the change request for the downlink modulation parameter is acquired by the change request acquisition unit;
Based on the degradation state of the received communication quality acquired by the communication quality acquisition unit, the downlink modulation parameter is changed to a low rate modulation parameter with a low transmission rate, or the communication channel is changed in the wireless communication path. A communication control unit for determining whether to change to a different communication channel;
A radio base station comprising: a communication processing unit that changes the downlink modulation parameter or the communication channel based on the change to the low-rate modulation parameter by the communication control unit or the determination to change to the different communication channel . A radio communication terminal capable of changing a modulation parameter of a radio channel set up with a radio base station using a communication channel defined by at least a frequency or a time slot to be used,
A communication quality acquisition unit for acquiring the reception communication quality of a communication channel currently used in the wireless communication path and the reception communication quality of an empty communication channel in the wireless communication path ;
Based on the received communication quality of the communication channel currently used in the wireless communication channel acquired by the communication quality acquisition unit, it is determined that the modulation parameter needs to be changed to a low rate modulation parameter with a low transmission rate If the received communication quality of the empty communication channel exceeds a predetermined threshold, the change to the empty communication channel is determined, and if the received communication quality of the empty communication channel does not exceed the predetermined threshold A communication control unit that determines to change the modulation parameter to the low-rate modulation parameter;
A wireless communication terminal comprising: a communication processing unit that changes the modulation parameter or the communication channel based on the change to the low-rate modulation parameter or the change to the free communication channel by the communication control unit. The communication quality acquisition unit acquires a reception level of a desired wave in the communication channel and a ratio between the reception level of the desired wave and an unnecessary wave,
The wireless communication terminal according to claim 5, wherein the communication control unit determines a change to the empty communication channel based on a reception level of the desired wave and a ratio between the reception level of the desired wave and the unnecessary wave. The communication quality acquisition unit acquires a fading speed of a desired wave in the communication channel,
The wireless communication terminal according to claim 5, wherein the communication control unit determines to change to the free communication channel when a fading speed of the desired wave exceeds a predetermined threshold. A communication method capable of changing a modulation parameter of a wireless communication channel set between a wireless communication terminal and a wireless base station using a communication channel defined by at least a frequency or a time slot to be used,
Obtaining the received communication quality of a communication channel currently used in the wireless communication path and the received communication quality of an empty communication channel in the wireless communication path ;
Based on the received communication quality of the communication channel currently used in the wireless communication channel acquired by the communication quality acquisition unit, it is determined that the modulation parameter needs to be changed to a low rate modulation parameter with a low transmission rate If the received communication quality of the empty communication channel exceeds a predetermined threshold, the change to the empty communication channel is determined, and if the received communication quality of the empty communication channel does not exceed the predetermined threshold Deciding to change the modulation parameter to the low rate modulation parameter;
And changing the modulation parameter or the communication channel based on the change to the low-rate modulation parameter in the determining step or the determination of the change to the free communication channel. A communication method capable of changing a modulation parameter of a wireless communication channel set between a wireless communication terminal and a wireless base station using a communication channel defined by at least a frequency or a time slot to be used,
Obtaining a downlink modulation parameter change request from the wireless communication terminal;
A step of acquiring a received communication quality of a communication channel currently used in the wireless communication path when the downlink modulation parameter change request is acquired in the acquiring step;
Based on the degradation state of the received communication quality acquired in the acquiring step, the downlink modulation parameter is changed to a low rate modulation parameter with a low transmission rate, or the communication channel is different in the wireless communication path. Determining whether to change to a communication channel;
Changing the downlink modulation parameter or the communication channel based on the change to the low rate modulation parameter in the determining step or the determination of the change to the different communication channel.

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