JP2009171592A - Mobile communication system, base station and subscriber station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a mobile communication system capable of speedily changing a transmission rate of data during communication. <P>SOLUTION: When a subscriber station MS11 receives TS change information from a base station 1, a time slot of a frame received from the base station 1 is changed in accordance with the TS change information. When the base station 1 receives TS change information from the subscriber station MS11, on the other hand, in accordance with the TS change information, a time slot of a frame received from the subscriber station MS11 is changed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mobile communication system in which an uplink transmission rate and a downlink transmission rate can be set independently.

A mobile communication system has a configuration in which a mobile station (for example, a mobile in-vehicle communication device, a mobile portable communication device, etc.), which is a subscriber station, and a base station are connected via a wireless channel.
In these mobile communication systems, sharing of radio frequency spectrum by different radio schemes (hereinafter referred to as “frequency sharing”) may be implemented by FDMA / TDMA schemes. Frequency sharing has already been implemented. Handover with these methods is already known.
For example, with respect to a time-slot shared mobile communication system in which a TDMA signal and a time-division CDMA signal are shared in the same time slot, US Pat. No. 5,805,581 (Japanese Patent Laid-Open No. 8-130766, EP701337A) already applied for ).

In such a mobile communication system, for example, when constructing multimedia, the uplink communication capacity in which the subscriber station transmits data to the base station, and the downlink communication in which the base station transmits data to the subscriber station. It is necessary to set the capacity independently. Also, in order to cope with fluctuations in the amount of data transmission during communication, it is necessary to establish a system that can change the data transmission rate.
For example, when a situation occurs in which the transmission amount of data transmitted from the subscriber station to the base station increases instantaneously, the subscriber station grasps the increase amount of the data transmission amount, calculates the necessary transmission rate, and transmits the transmission rate. A change request is sent to the base station.

When the base station receives a transmission rate change request from the subscriber station, the base station determines whether it is in a state where it can accept the change of the transmission rate by searching for a free channel or the like currently being communicated.
When the base station determines that it can accept the change in the transmission rate, it transmits the identification number of the communication channel to be used thereafter to the subscriber station.
After transmitting a transmission rate change request to the base station, the subscriber station receives an identification number of a communication channel to be used later from the base station, and thereafter transmits data to the base station using the communication channel.
As a result, the data transmission rate is changed, but a process for obtaining permission of the partner station is required before the transmission rate is actually changed after the data transmission amount fluctuates. It is necessary to allow a considerable waiting time until the transmission rate is actually changed.

  Therefore, in a mobile communication system in which the amount of fluctuation of the data transmission amount is large and it is difficult to expect a considerable waiting time, a method of fixing at a large transmission rate by allocating a large frequency band from the beginning of communication is adopted. .

  Since the conventional mobile communication system is configured as described above, a transmission rate change request can be transmitted to the partner station, and if the partner station's permission is obtained, the transmission rate can be changed. Since a considerable amount of time is required until the rate is changed, there is a problem that, when the data transmission amount fluctuates greatly, data congestion occurs and the real-time property of the data is impaired.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a mobile communication system capable of quickly changing a data transmission rate during communication.

In the mobile communication system according to the present invention, when time slot change information is received from the base station change request means, the time slot of data received from the base station is changed according to the time slot change information. .
Also, when changing the data transmission rate, the quality of the transmission rate change is determined with reference to the transmittable power of the transmitter in the base station.

According to the present invention, when the time slot change information is received from the base station change request means, the time slot of the data received from the base station is changed according to the time slot change information. Since a new time slot can be used from the time of transmission, there is an effect that the real-time property of data can be ensured even when the amount of data transmission varies greatly.
In addition, when changing the data transmission rate, it is configured to determine whether the transmission rate change is good or not by referring to the transmittable power of the transmitter in the base station, so that the wireless connection is disconnected along with the change of the time slot. There is an effect that can solve the problem.

1 is an overall configuration diagram showing a mobile communication system according to Embodiment 1 of the present invention. It is explanatory drawing which shows the structural example of the time slot for PCS and cellular by TDMA and time division CDMA. It is explanatory drawing which shows the other structural example of the time slot for PCS and cellular by TDMA and time division CDMA. It is explanatory drawing which shows an example of the transmission rate of the radio | wireless connection which comprises the uplink and downlink which connect a subscriber station and a base station. FIG. 5 is an explanatory diagram showing a list of channels to which time slots used for transmission of the next frame are virtually allocated in advance among the transmittable data rates shown in FIG. 4. It is a state transition diagram which shows channel switching. It is a block diagram which shows the inside (change request | requirement means) of the base station of the mobile communication system by Embodiment 1 of this invention. It is a block diagram which shows the time slot structure in a flame | frame. It is explanatory drawing which shows the time slot virtually allocated to each channel, and the actual use time slot of each channel. FIG. 5 is an explanatory diagram showing a state in which a virtual channel is newly assigned to a time slot that has been batting because one of the time slots virtually assigned to each channel has actually been used. It is a block diagram which shows the time slot structure in a flame | frame. It is a block diagram which shows the time slot structure in a flame | frame. It is a flowchart which shows operation | movement of the mobile communication system by Embodiment 6 of this invention. It is a block diagram which shows the inside (change request | requirement means) of the subscriber station of the mobile communication system by Embodiment 7 of this invention. It is a block diagram which shows the time slot change means of the base station which receives TS change information from a subscriber station and changes a time slot. It is a block diagram which shows the inside of a mobile switching center.

Hereinafter, in order to describe the present invention in more detail, the best mode for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 is an overall configuration diagram showing a mobile communication system according to Embodiment 1 of the present invention, in which 1 to 3 are base stations, 4 is a mobile switching center for controlling base stations 1 and 3, and 5 is a base station. A mobile switching center 6 controls PSTN (Public Switching Telephone Network), which is a public system to which mobile switching centers 4 and 5 are connected by wire.

MS11 to MS14 are mobile stations such as mobile in-vehicle communication devices or mobile portable communication devices that are wirelessly connected to any of the base stations 1 to 3, and WS21 to WS23 are semi-fixed or fixed that are wirelessly connected to any of the base stations 1 to 3. FWA (Fixed Wireless Access) stations.
The mobile station and the FWA station perform radio communication with any of the base stations 1 to 3 via a low-speed TDMA data channel, a medium / high-speed TDMA data channel, a time division CDMA channel, etc. And has a function of executing voice or low-speed data communication. Hereinafter, mobile stations and FWA stations are collectively referred to as subscriber stations.

  In the first embodiment, the mobile switching centers 4 and 5 are wired to the PSTN 6, but the mobile switching stations 4 and 5 side interfaces of the base stations 1 to 3, the mobile switching stations 4 and 5 and the PSTN 6 are connected. Will be described as having an ATM (Asynchronous Transfer Mode) mode communication function that is an asynchronous transfer mode in addition to the normal communication mode, and communicating in the ATM mode.

  Further, the subscriber stations MS11 to MS14, WS21 to WS23 and the base station exchange signals using a digital modulation method, for example, FDMA / TDD (Time Division) which is frequency division division access / time division bidirectional communication. Duplex), code division multiple access / code division multiple access / time division duplex (CDMA / TDD), multi-carrier time division multiple access / frequency division duplex (TDMA / FDD) -Carriers Time Division Multiple Access / Frequency Division Duplex), TDMA / TDD, time division CDMA / F D method, shall be wirelessly connected in a time division CDMA / TDD method, or the like.

FIG. 2 is an explanatory diagram showing a configuration example of a time slot for PCS (Personal Communication System) and cellular using TDMA and time division CDMA. In the figure, # 31-0A to 3A are PCS high-speed data transmission downlinks in the first frame. Time-division CDMA time slots for lines, # 31-0B to 3B, are the same time slots in the first frame uplink.
# 32-0A to # 32-3B are time division CDMA time slots for PCS low-speed data transmission in the first frame, and # 33-1A to # 33-2B and # 35-1A to # 35-2B are the first frame. The PCS low-speed data transmission TDMA time slots # 34-0A to # 34-3B are the first frame PCS medium-speed data transmission TDMA time slots.
# 36-1A to # 36-2B are TDMA time slots for PCS high-speed data transmission of the first frame, # 35-0A to # 35-3B are TDMA time slots for cellular low-speed data transmission of the first frame, # 37 −0A to # 37-3B are time division CDMA time slots for cellular high-speed data transmission of the first and second frames.

Note that FIG. 2 represents Up-Link and Down-Link of TDD (Time Division Duplex), and Up-Link is a time slot represented by R1 _0B to R1 _3B on the time axis, and Down-Link. is a time slot which is represented by _T1 0A _{to T1 3A} and _T2 0A _{to T2 3A} on the time axis. Up-Link time slots R1 _{0B to} R1 _3B and Down-Link time slots T1 _{0A to} T1 _3A constitute one frame, and time slots T2 _{0A to} T2 _3A are time slots belonging to the next frame. is there. That is, FIG. 2 represents 1 frame and 1/2 frame.

Next, FIG. 3 is an explanatory diagram showing another configuration example of PCS and cellular time slots by TDMA and time division CDMA. In the figure, the same names as those shown in FIG. 2 perform the same operations. Therefore, explanation is omitted.
# 31-4A to # 31-5A are asymmetrical portions of Down-Link in the time division CDMA time slot for PCS high-speed data transmission in the first frame, and the amount of transmission information from the base station to the subscriber station is This time slot is used when the transmission information transmission amount from the subscriber station to the base station is larger.
# 31-0B to # 31-1B are Up-Link time slots in the first frame. That is, all the time slots included in the time slots T1 _{0A to} T1 _5A are time slots belonging to the Down-Link in the first and other frames. Similarly, all the time slots included in R1 _0B to R1 _1B are time slots belonging to the Up-Link in the first and other frames.

  FIG. 3 shows a case of TDD asymmetry in which the Up-Link time and the Down-Link time are different in the TDD frame time length. The present invention is applied not only to the symmetric time TDD system as shown in FIG. 2, but also to the asymmetric TDD system as shown in FIG. 3, and is a communication line for connecting a base station and a subscriber station. This includes the case where the transmission amount of the uplink and the downlink is different.

Next, FIG. 4 is an explanatory diagram showing an example of the transmission rate of the wireless connection that configures the uplink and downlink connecting the subscriber station and the base station, and depending on the type of multimedia used by the subscriber station, It shows that the usable transmission rates are different.
Here, the transmission rate indicated as “intermittent” is a transmission rate of 1 kbps or less, and “intermittent” is connected to the multiframe only once in the mobile communication system, and the subscriber station is processing its own information. Therefore, during this period, communication between the base station and the subscriber station is not necessary, but the low-speed transmission rate is used when the line is not disconnected.

FIG. 5 is an explanatory diagram showing a list of channels to which time slots used for transmission of the next frame are virtually allocated in advance and actual used channels among the transmittable data rates shown in FIG.
For example, in the case of the subscriber station number 199808028 (MS11), seven types of transmission rates from 1 kbps to 1024 kbps including “intermittent” can be set on the uplink (see FIG. 4). Types of channels (first channel to fourth channel) are set as usable channels. That is, FIG. 5 defines the types of speeds that can change the transmission speed during a call.

This setting defines the types of speech channels that can be dynamically assigned (Dynamic Channel Assignment).
Note that the # 31-0B time slot is set in the Up-Link of the subscriber station number 19980601 (WS21) and the subscriber station number 19980614 (WS23), respectively, and data with a transmission rate of 1024 kbps is transferred from the subscriber station to the base station. Although transmitted, this radio wave is TD-CDMA, so that the same time slot is shared by a plurality of signals. As a matter of course, the spread codes of a plurality of radio waves sharing the same time slot are selected so as to be orthogonal to each other. However, in FIG. 5, information regarding this code is omitted.

  In addition, the fourth channel (# 31-1A time slot with a transmission rate of 2048 kbps) is currently used for the Down-Link of the subscriber station number 199808028 (MS11) in FIG. For example, when it is necessary to switch the Down-Link to the second channel (# 32-1A time slot with a transmission rate of 2 kbps) in order to execute small-capacity information transmission after the termination, the channel switching is immediately performed at that time. Executed.

  FIG. 6 is a state transition diagram showing channel switching. The state transition diagram shows a channel state of a downlink or an uplink between one subscriber station and one base station. If the subscriber station is wirelessly connected to the base station, there will be a state transition diagram that is a multiple of the subscriber station. Moreover, since each subscriber station has a different state, it goes without saying that the mobile switching centers 4 and 5 grasp and control the current state of the subscriber station wirelessly connected to the base station to be controlled. .

  FIG. 7 is a block diagram showing the interior (change request means) of the base station of the mobile communication system according to the first embodiment of the present invention. In the figure, 61 receives ATM information arriving from PSTN 6 from mobile switching center 4. A network interface 62 is a FIFO (Fast-in-Fast-out) memory for storing ATM information received by the network interface 61, and 63 is a remaining information amount of ATM information currently stored in the FIFO memory 62 (still a subscriber A memory measuring instrument 64 for measuring the instantaneous transmission amount of data not transmitted to the station, and a clock generator oscillating a clock.

65 is a time slot processor for executing a selection process for selecting a time slot to be used for transmission of the next frame in accordance with the remaining information amount of ATM information measured by the memory measuring device 63, and 66 is a channel currently used. A real channel memory to be stored, 67 is a virtual channel memory in which a time slot used for transmission of the next frame is virtually allocated in advance, and 68 is transmitted from the FIFO memory 62 to the subscriber station under the direction of the time slot processor 65 69. A frame composer that extracts ATM information, adds TS change information (change information of a time slot used for transmission of the next frame) and check information to the ATM information, and constructs a frame to be transmitted to the subscriber station. Is a local oscillator that generates a carrier wave under the direction of the time slot processor 65, and A modulator for modulating the frame built by chromatography beam structure 68 in the carrier local oscillator 69 is generated.
Reference numeral 71 denotes an amplifier that amplifies the carrier wave output from the modulator 70, 72 denotes a diplexer, 73 denotes an antenna, and 74 denotes a receiving unit.

Next, the operation will be described.
In the first embodiment, a case where the transmission rate is changed when the base station 1 transmits ATM information to the subscriber station MS11 will be described.
First, when the network interface 61 receives the ATM information coming from the PSTN 6 from the mobile switching center 4 (see FIG. 16), the network interface 61 stores the ATM information in the FIFO memory 62.
However, because of the characteristics of the ATM transmission method, the transmission speed of ATM information received by the network interface 61 is not constant. For example, if the transmission speed of ATM information that is extracted from the FIFO memory 62 and transmitted is constant, the FIFO memory 62 The remaining information amount of the accumulated ATM information varies.
Therefore, the memory measuring device 63 measures the remaining information amount of the ATM information currently stored in the FIFO memory 62 and outputs the remaining information amount of the ATM information to the time slot processor 65.

When the remaining information amount of the ATM information has changed since the previous frame transmission, the time slot processor 65 outputs a TS change information addition command to the frame composer 68 in order to suppress fluctuations in the remaining information amount. .
Specifically, in the downlink of the subscriber station MS11, when the remaining information amount in the FIFO memory 62 is Z, the inequality in which the inequality sign is established is searched from the following four inequalities, and the inequality to be established is satisfied. Is selected as a time slot to be used for transmission of the next frame (see FIG. 5). However, here, it is assumed that the time length of one frame is 10 ms.

(1) 20.48 kb ≦ Z
→ 4th channel (2048-kbps # 31-1A time slot)
(2) 320b ≦ Z <20.48 kb
→ Third channel (32 kbps # 37-0A time slot)
(3) 20b ≦ Z <320b
→ second channel (2kbps # 32-1A time slot)
(4) Z <20b
→ 1st channel (intermittent # 35-0A time slot)

Therefore, when the amount of remaining information in the FIFO memory 62 becomes, for example, 20.48 kb (= 2048 kbps × 10 ms) or more, the # 31-1A time slot whose transmission rate set to the fourth channel is 2048 kbps is used for transmission of the next frame. Will be selected.
In this way, when the time slot processor 65 selects a time slot to be used for transmission of the next frame, a TS change information addition command indicating the time slot and a frame construction command are output to the frame composer 68 (however, When the TS change information addition command is also used as the frame construction command, the frame construction command is not required).
However, if the remaining information amount of ATM information has not changed since the previous frame transmission, there is no need to change the transmission rate of the next frame, so that a TS change information addition command is not output to the frame composer 68. The frame construction command 68 is simply output to the frame construction unit 68.

When the frame composer 68 receives the TS change information addition command and the frame construction command from the time slot processor 65, as shown in FIG. 8, the ATM information extracted from the FIFO memory 62 (the amount of ATM information extracted is This is determined in response to an instruction from the time slot processor 65, and is an extraction amount corresponding to the transmission rate of the time slot determined at the time of transmitting the previous frame, for example, the # 31-1A time slot having a transmission speed of 2048 kbps last time. Is selected, TS change information and check information (for example, a CRC code) are added to the FIFO memory 62 to extract ATM information for 20.48 kb, and a frame to be transmitted to the subscriber station MS11 is formed. .
When only a frame construction command is received, check information is added to ATM information to form a frame.

On the other hand, the local oscillator 69 generates a carrier wave under the instruction of the time slot processor 65. That is, a carrier wave corresponding to the transmission rate of the time slot determined at the time of transmitting the previous frame is generated.
Then, when the frame constructer 68 constructs a frame to be transmitted this time, the modulator 70 modulates the frame into a carrier wave generated by the local oscillator 69, outputs the frame to the amplifier 71, and emits it as a radio wave from the antenna 73.
Thus, when a radio wave is emitted from the antenna 73, the subscriber station MS11 receives the radio wave.
When the time slot changing means of the subscriber station MS11 reads the TS change information constituting the frame from the radio wave, the transmission rate at the time of receiving the next frame according to the TS change information, that is, the time used for receiving the next frame Change the slot.

  As is apparent from the above, according to the first embodiment, when the subscriber station MS11 receives TS change information from the base station 1, the time slot of the frame received from the base station 1 is changed according to the TS change information. Since configured as described above, the base station 1 can use a new time slot from the time of transmission of the next frame without receiving a return of permission / refusal information accompanying transmission of TS change information. Even when the transmission amount of ATM information varies greatly, there is an effect that the real-time property of ATM information can be ensured.

Embodiment 2. FIG.
In the first embodiment, when the time slot processor 65 selects a time slot to be used for transmission of the next frame in accordance with the remaining information amount of ATM information, an inequality in which an inequality sign is established is searched, and the inequality to be established is dealt with. As shown in FIG. 9, it is necessary to virtually assign a time slot in advance to each channel to change the transmission rate, as shown in FIG. It is also possible to use a channel to which a time slot that satisfies a certain transmission rate is assigned.

That is, when it is necessary to change the transmission rate, the time slot processor 65 determines the transmission rate of the next frame from the remaining information amount of ATM information. Specifically, if the time length of one frame is 10 ms, the transmission rate of the next frame is provisionally determined by multiplying the remaining amount of ATM information by 100.
For example, when the remaining information amount of ATM information is 350 b, the transmission rate of the next frame is provisionally determined to be 35 Kbps.

When the time slot processor 65 temporarily determines the transmission rate of the next frame, the time slot processor 65 refers to the virtual channel memory 67 in which a time slot is virtually allocated to each channel, and selects a channel that satisfies the temporarily determined transmission rate. To do. For example, if the transmission rate of the downlink transmitted to the subscriber station MS11 is provisionally determined to be 35 Kbps, the third channel (32 kbps # 37-0A time slot) is selected.
When the time slot processor 65 selects a channel that satisfies the provisionally determined transmission rate, the time slot processor 65 transfers the channel information to the real channel memory 66 and executes processing for changing the transmission rate of the next frame. As in the first mode, the process of adding the TS change information to the ATM information and transmitting it to the subscriber station MS11 is executed.

  Since it takes some time to update the stored contents of the actual channel memory 66 after the transmission rate change request is generated, the same time slot is assigned to a plurality of locations (in the case of FIG. The same time slot is assigned to the third channel of the downlink of the subscriber station MS11 and the third channel of the downlink of the subscriber station MS12), and transmission rate change requests for a plurality of radio channels are substantially at the same time. If this occurs, it may not be possible to change the transmission rate for one wireless line.

  For example, when the downlink of the subscriber station MS11 is changed to the third channel (32 kbps # 37-0A time slot), the downlink of the subscriber station MS12 is changed to the third channel (32 kbps # 37-0A time slot). As shown in FIG. 10, among the currently unused time slots, a time slot (for example, # 37-3A time slot) equal to the transmission speed of the # 37-0A time slot is selected as the third time slot. Execute the process assigned to the channel.

As a result, the downlink of the subscriber station MS12 is changed to the third channel (# 37-3A time slot of 32 kbps).
In addition, according to the second embodiment, when changing the time slot, a channel that can be used in advance is allocated in advance, so that an effect that the channel can be quickly switched is obtained.

Embodiment 3 FIG.
In the first embodiment, when the time slot processor 65 transmits the TS change information to the subscriber station, the subscriber station immediately changes the time slot. However, the reservation information indicating the change timing of the time slot is shown. It may be transmitted to the subscriber station, and the subscriber station may determine the change timing of the time slot according to the reservation information.

That is, when the time slot processor 65 adds TS change information to ATM information, as shown in FIG. 11, reservation information (for example, “−5”) indicating the change timing of the time slot is added as reservation information. In this case, the time slot is changed after 5 frames) is added to the ATM information.
Then, when the subscriber station receives the ATM information to which the TS change information and the reservation information are added, the time slot is changed according to the TS change information as in the first embodiment, but it is not necessarily after the TS change information is received. The time slot change timing is determined according to the reservation information, without being changed immediately.
For example, when “−5” is added as the reservation information, it is changed to use a new time slot from a frame received after 5 frames.

  Every time the time slot processor 65 transmits ATM information, the reservation information is counted up (“−5” → “−4” → “−3” → “−2” → “−1” → “0”). When the reservation information becomes “0”, the subscriber station may change the time slot. However, the time slot processor 65 transmits the reservation information only once, and the subscriber station receives the reservation information after receiving the reservation information. The number of frame receptions may be counted to obtain the time slot change timing.

  As apparent from the above, according to the third embodiment, when the TS change information is transmitted to the subscriber station, the reservation information indicating the change timing of the time slot is transmitted to the subscriber station. As a result, time slot change processing can be prepared in anticipation of fluctuations in the amount of data transmission, and as a result, time slot change processing can be performed with a margin. There is also an effect that can be done. It is also possible to reserve a slot that does not include ATM information in the previous frame (for example, if the reservation information is “2”, then no information is included in the time slot between the two frames). If the time-division CDMA method is adopted, the equivalent noise can be reduced.

Embodiment 4 FIG.
In the third embodiment, the reservation information is transmitted to the subscriber station, and the subscriber station determines the change timing of the time slot according to the reservation information. However, in this case, after the TS change information is transmitted, Since the time slot is changed several frames later, the use of the time slot may be disabled as a result of other subscriber stations using the time slot during that time.

Therefore, in the fourth embodiment, if the time slot becomes unavailable before the time slot changing means of the subscriber station changes the time slot, as shown in FIG. TS correction information designating a slot is transmitted to the subscriber station.
As a result, the time slot changing means of the subscriber station changes the time slot according to the TS correction information, so that the necessary transmission rate can be ensured even if the original time slot becomes unusable. Play.

Embodiment 5 FIG.
In the fourth embodiment, the reservation information is transmitted to the subscriber station, and the subscriber station determines the change timing of the time slot according to the reservation information. However, the time slot virtually allocated to each channel is shown. You may make a reservation for a change.
That is, when the time slot processor 65 transmits the reservation information to the subscriber station, the time slot is changed after several frames, so that the contents stored in the virtual channel memory 67 are reflected in the real channel memory 66. In order to cope with the fluctuation of the transmission capacity that occurs, a reservation for updating the storage contents of the virtual channel memory 67 may be received in advance after several frames.

For example, after several frames, a reservation for virtually allocating # 32-2A to the downlink of the second channel of the subscriber station MS11 is executed.
As a result, it is possible to prepare in advance the change of the time slot virtually allocated to each channel.

Embodiment 6 FIG.
In the first to fifth embodiments, the time slot processor 65 transmits the TS change information, and the subscriber station changes the time slot according to the TS change information. However, if the time slot is changed unconditionally, There is a risk of disconnecting.
Therefore, in the sixth embodiment, the change of the time slot is permitted only when the state of the currently connected wireless communication has a predetermined condition.

Specifically, as shown in FIG. 13, when a transmission capacity change request is generated (step ST1), the time slot processor 65 determines whether or not the changed transmission capacity is greater than the currently transmitted transmission capacity. Judgment is made (step ST2).
When the transmission capacity after the change increases from the transmission capacity currently under communication, the amount of increase in transmission power accompanying the increase in the transmission capacity is calculated from the current transmission speed DR1 and the transmission speed DR2 after the change (step) ST3).
C (dB) = 10 × log (DR2 / DR1)

Then, after calculating the transmission power increase amount C, the time slot processor 65 determines whether or not the transmitter of the base station can increase the transmission power by C (dB) from the present time (step ST4).
If the transmitter of the base station can increase the transmission power by C (dB) from the present time, the transmission capacity can be changed because there is little risk of disconnection of the wireless connection even if the transmission capacity is increased (step). ST5), TS change information is transmitted to the subscriber station as in the first to fifth embodiments.

  On the other hand, if the transmitter of the base station cannot increase the transmission power by C (dB) from the present, there is a high risk that the wireless connection will be disconnected if the transmission capacity is increased. Step ST6), the transmission of TS change information is stopped. However, when the transmission power of the transmitter of the base station can be increased to some extent, the transmission capacity corresponding to the increase amount may be set and the TS change information may be transmitted.

The time slot processor 65 compares the reception sensitivity of the receiver of the subscriber station with the minimum reception sensitivity when the transmission capacity after the change is smaller than the transmission capacity currently being communicated, and receives the reception of the receiver of the subscriber station. It is determined whether or not the sensitivity is greater than AdB by more than the minimum reception sensitivity (step ST7).
That is, if the receiver sensitivity of the subscriber station receiver is greater than AdB than the minimum receiver sensitivity, there is less risk of disconnection of the wireless connection even if the time slot is changed. Send information to the subscriber station.

On the other hand, since the reception sensitivity of the receiver of the subscriber station is small, there is no large difference from the minimum reception sensitivity, and if it is not larger than AdB more than the minimum reception sensitivity, changing the time slot causes the wireless connection to be disconnected. Therefore, it is determined whether or not the transmitter of the base station can increase the transmission power by A (dB) from the present (step ST8).
In other words, even if the receiver sensitivity is low, if the transmitter transmission power increases, the possibility of wireless connection disconnection will decrease even if the time slot is changed. It is determined whether or not the transmission power can be increased by A (dB).

When the transmitter of the base station can increase the transmission power by A (dB) from the present time, the transmission capacity is changed and TS change information is transmitted to the subscriber station.
If the transmitter of the base station cannot increase the transmission power by A (dB) from the present time, the transmission capacity change is not permitted (step ST6), and the transmission of the TS change information is stopped.

  As can be seen from the above, according to the sixth embodiment, when the transmission capacity increases, the transmission rate of the transmitter in the base station is referred to determine the quality of the transmission rate change, and the transmission capacity decreases. In this case, it is configured to determine whether the transmission rate change is good or not by referring to the reception sensitivity of the receiver in the subscriber station and the transmittable power of the transmitter in the base station. The effect which can eliminate the malfunction which is cut | disconnected.

Embodiment 7 FIG.
FIG. 14 is a block diagram showing the interior (change request means) of a subscriber station of a mobile communication system according to Embodiment 7 of the present invention. In FIG. 14, reference numeral 81 denotes a keyboard, an image display unit, a voice input / output unit, etc. A machine interface 82 is a FIFO memory for storing data input by the man-machine interface 81, and 83 is a residual information amount of data currently stored in the FIFO memory 82 (instant transmission of data not yet transmitted to the subscriber station). 84 is a clock generator that oscillates a clock.

A time slot processor 85 executes a selection process for selecting a time slot to be used for transmission of the next frame in accordance with the remaining information amount of data measured by the memory measuring device 83, and 86 stores a currently used channel. The actual channel memory 87 is a virtual channel memory in which a time slot used for transmission of the next frame is virtually allocated in advance, and 88 is data transmitted from the FIFO memory 82 to the subscriber station under the direction of the time slot processor 85. A frame composer for constructing a frame to be transmitted to the subscriber station by adding TS change information or check information to the data, 89 is a local oscillator that generates a carrier wave under the direction of the time slot processor 85, 90, a local oscillator 89 generates a frame constructed by the frame composer 88. A modulator for modulating the transmit.
91 is an amplifier that amplifies the carrier wave output from the modulator 90, 92 is a diplexer, 93 is an antenna, and 94 is a receiver.

Next, the operation will be described.
In the first to sixth embodiments, the base station has instructed the subscriber station to change the time slot. However, the change request means similar to the base station change request means shown in FIG. The subscriber station may actively change the time slot by incorporating it in the station (see FIG. 14).
That is, the time slot processor 85 of the subscriber station uses a time slot used for transmission of the next frame (or a time slot used for transmission after several frames) according to the remaining information amount of data measured by the memory measuring device 83. The frame may be determined and the TS change information or reservation information added to the transmission data may be transmitted to the base station.

Since the main body of changing the transmission rate is changed from the base station to the subscriber station, it is the same as in Embodiments 1 to 6 above, and detailed description thereof is omitted.
Incidentally, FIG. 15 is a block diagram showing the time slot changing means of the base station that receives the TS change information from the subscriber station and changes the time slot (the time slot changing means of the subscriber station is also substantially the same configuration). ), 101 is a receiving unit that receives a frame to which TS change information is added, 102 is a receiving local oscillator, 103 is a demodulator that demodulates the frame received by the receiving unit 101, and 104 is demodulated by the demodulator 103. The frame decoder / data detector outputs the TS change information to the time slot processor 65 when the received frame is decoded and TS change information is detected.
When receiving the TS change information from the frame decoding / data detector 104, the time slot processor 65 changes the time slot used for receiving the next frame according to the TS change information.

  As described above, the mobile communication system according to the present invention has communication channels in which the uplink communication capacity and the downlink communication capacity are different, and includes both time division multiple access (TDMA), code division multiple access, and time division. It is suitable to use transmission systems such as a directional (CDMA / TDD) system and a time-divided CDMA (Time Divided CDMA) system.

  1-3 base stations, 4,5 mobile switching centers, 6 PSTN, MS11-MS14 mobile stations, WS21-WS23 FWA stations, 61 network interfaces, 62 FIFO memories, 63 memory instruments, 64 clock generators, 65 time slot processors , 66 Real channel memory, 67 Virtual channel memory, 68 Frame composer, 69 Local oscillator, 70 Modulator, 71 Amplifier, 72 Diplexer, 73 Antenna, 74 Receiver, 81 Man-machine interface, 82 FIFO memory, 83 Memory instrument , 84 clock generator, 85 time slot processor, 86 real channel memory, 87 virtual channel memory, 88 frame composer, 89 local oscillator, 90 modulator, 91 amplifier, 92 diplexer, 93 antenna NA, 94 receiving unit, 101 receiving unit, 102 receiving local oscillator, 103 demodulator, 104 frame decoding / data detector.

Claims (24)

When it is necessary to change the transmission rate of data transmitted to a wirelessly connected subscriber station, the base station change request means for transmitting time slot change information to the subscriber station, and the base station change request Receiving time slot change information from the means, the subscriber station time slot changing means for changing the time slot of the data received from the base station according to the time slot change information,
The base station change request means, when changing the data transmission rate, refers to the transmittable power of the transmitter in the base station to determine whether the transmission rate change is good or bad.   The mobile station according to claim 1, wherein the change request means of the base station transmits the change information of the time slot to the subscriber station, using the changed time slot from the data included in the next frame. Communications system.   The mobile communication system according to claim 1, wherein the change request means of the base station determines a transmission rate according to an instantaneous transmission amount of data transmitted to the subscriber station.   4. The mobile station according to claim 3, wherein the change request means of the base station grasps the instantaneous transmission amount of data from the data amount of data not transmitted to the subscriber station among the data received from the switching center. Communications system.   When transmitting the time slot change information to the subscriber station, the base station change request means obtains the time slot change information from the virtual channel memory in which the time slot used for transmission of the next frame is virtually allocated in advance. The mobile communication system according to claim 1, wherein the mobile communication system acquires and transmits.   The mobile station according to claim 1, wherein the base station change request means transmits the reservation information indicating the time slot change timing to the subscriber station when the time slot change information is transmitted to the subscriber station. Communications system.   7. The mobile communication system according to claim 6, wherein the time slot changing means of the subscriber station determines the change timing of the time slot according to the reservation information transmitted from the base station.   The base station change request means transmits the time slot change information and reservation information to the subscriber station, and when the time slot becomes unavailable before the subscriber station time slot change means changes the time slot, 7. The mobile communication system according to claim 6, wherein time slot change information for designating another time slot is transmitted to the subscriber station.   When the time slot changing means of the subscriber station receives time slot change information designating another time slot from the base station change requesting means, the data slot received from the base station according to the time slot change information is received. The mobile communication system according to claim 8, wherein the time slot is changed.   2. The mobile communication system according to claim 1, wherein, when the data transmission rate is increased, the base station change request means determines whether the transmission rate change is good or not by referring to the transmittable power of the transmitter in the base station. .   When the data transmission rate is lowered, the base station change request means determines whether or not the transmission rate change is good by referring to the receiver sensitivity at the subscriber station and the transmittable power of the transmitter at the base station. The mobile communication system according to claim 1. When it is necessary to change the transmission rate of data transmitted to a wirelessly connected base station, the subscriber station change request means for transmitting time slot change information to the base station, and the subscriber station change request Receiving time slot change information from the means, the base station time slot changing means for changing the time slot of the data received from the subscriber station according to the time slot change information,
The subscriber station change request means, when changing the data transmission rate, refers to the transmittable power of the transmitter in the subscriber station to determine whether the transmission rate change is good or bad. .   The subscriber station change request means, when transmitting the time slot change information to the base station, transmits using the changed time slot from the data included in the next frame. 12. The mobile communication system according to 12.   13. The mobile communication system according to claim 12, wherein the change request means of the subscriber station determines a transmission rate according to an instantaneous transmission amount of data to be transmitted to the base station.   15. The mobile communication according to claim 14, wherein the change request means of the subscriber station grasps an instantaneous transmission amount of data from a data amount of data not transmitted to the base station among data received from the man-machine interface. system.   When the change request means of the subscriber station transmits the change information of the time slot to the base station, the change information of the time slot is obtained from the virtual channel memory in which the time slot used for transmission of the next frame is virtually allocated in advance. The mobile communication system according to claim 12, wherein the mobile communication system acquires and transmits.   13. The mobile communication according to claim 12, wherein the change request means of the subscriber station transmits the reservation information indicating the change timing of the time slot to the base station when transmitting the change information of the time slot to the base station. system.   18. The mobile communication system according to claim 17, wherein the time slot changing means of the base station determines the change timing of the time slot according to the reservation information transmitted from the subscriber station.   After the time slot change information and the reservation information are transmitted to the base station, the subscriber station change request means, when the time slot becomes unavailable before the time slot change means of the base station changes the time slot, 18. The mobile communication system according to claim 17, wherein time slot change information for designating a time slot is transmitted to the base station.   When the time slot changing means of the base station receives time slot change information designating another time slot from the change request means of the subscriber station, the time slot of the data received from the subscriber station according to the change information of the time slot is received. The mobile communication system according to claim 19, wherein the slot is changed.   13. The movement according to claim 12, wherein when the data transmission rate is increased, the change request means of the subscriber station determines whether the transmission rate change is good or not by referring to the transmittable power of the transmitter in the subscriber station. Communications system.   When the data transmission rate is lowered, the subscriber station change request means refers to the reception sensitivity of the receiver at the base station and the transmittable power of the transmitter at the subscriber station to determine whether the transmission rate change is acceptable or not. The mobile communication system according to claim 12, characterized in that:   When it is necessary to change the transmission rate of data to be transmitted to a wirelessly connected subscriber station, change request means for transmitting time slot change information to the subscriber station, and when changing the data transmission rate, A base station comprising change determining means for determining whether or not the transmission rate is changed by referring to the transmittable power of the transmitter.   When it is necessary to change the transmission rate of data to be transmitted to a wirelessly connected base station, change request means for transmitting time slot change information to the base station, and when changing the data transmission rate, a transmitter A change determining means for determining whether or not the transmission rate is changed by referring to the transmittable power of the subscriber station.

Images