JP3895364B2 - Mobile communication system - Google Patents

Description

  The present invention relates to a mobile communication system using CDMA (Code Division Multiple Access), and in particular, a communication mode for controlling switching of a communication mode according to a communication situation between a base station and a mobile communication terminal. The present invention relates to a control method, a mobile communication system, a base station control device, a base station, and a mobile communication terminal.

  Conventional wireless multimode data communication methods include an autonomous mode for autonomously transmitting and receiving data, and a so-called scheduling mode for transmitting and receiving data according to a request (scheduling) for data transmission and reception such as communication timing permitted from the base station side. Are switched according to the data rate or the like (see, for example, Patent Document 1).

JP 2002-369261 A

In this communication method, for example, when packet data is transmitted between a base station and a wireless device at a low data rate of about 9.6 kbps, the autonomous mode is controlled. Conversely, when data is transmitted at a high data rate, the scheduling mode is controlled.
Here, in the scheduling mode, signaling for notifying scheduling from the base station to the wireless device is frequently transmitted. For this reason, if there is not a certain amount of data in one transmission, the efficiency of data transmission will be worse than the number of times of signaling.

In the conventional data communication method described above, the above problem is solved by controlling to the scheduling mode in the case of a high data rate with a large amount of data per unit time.
However, although the prior art document discloses that the conventional data communication method is switched to the autonomous mode or the scheduling mode mainly based on the data amount, the switching processing under other communication conditions is sufficient. No disclosure has been made.

  As communication conditions to be used as a reference in switching the communication mode, for example, considering the demodulation processing of encoded signals and the handling of data that requires real-time properties, for example, the amount of interference in the base station (hereinafter referred to as noise rise), Examples include delay.

In the invention disclosed in the above-mentioned prior art documents, wireless devices that perform data communication that cannot tolerate a delay are operated in an autonomous mode as much as possible, and devices that perform a communication that can tolerate a delay are operated in a schedule mode. Flexible communication mode switching according to the situation has not been sufficiently studied.
Further, in uplink packet communication using the CDMA system, if the interference of the transmission signal from the wireless device exceeds the limit of noise rise in the base station, the transmission signal cannot be demodulated.

  This noise rise also fluctuates due to interference from other cells or transmission from other wireless devices in the same cell. For this reason, in packet communication by the CDMA system, it is necessary to pay sufficient attention to noise rise management.

  Here, if a sufficient margin for noise rise is secured as noise rise management, the autonomous mode can be used even when the amount of data to be transmitted is large. In this case, there is an advantage that the number of times of signaling can be reduced as compared with the schedule mode and the delay is also small.

  In this way, by appropriately distributing the margin for noise rise due to various factors that vary depending on the state of communication traffic to the noise rise margin at the base station, efficient communication according to fluctuations in noise rise Is possible.

The present invention has been made to solve the above problems, allows efficient data communication in accordance with the variation in the noise rise caused by the variation in the communication load between the base Chikyoku the mobile communication terminal with An object is to obtain a mobile communication system .

A mobile communication system according to the present invention includes a mobile communication terminal, a base station that wirelessly communicates with the terminal, and a base station controller that controls the base station, and the terminal transmits an uplink to the base station. A terminal buffer for storing data, a buffer status information transmission unit for transmitting terminal buffer status information indicating the amount of data accumulated in the terminal buffer to the base station, and data to the base station according to an instruction regarding uplink radio resources by the base station A base station receives an interference amount measurement unit that measures the amount of interference related to the received signal, an interference amount notification unit that notifies the base station controller of the measured interference amount, and receives terminal buffer status information and a uplink radio resource instructing unit for instructing on the uplink radio resource to the terminal performs scheduling according to the terminal buffer state information and the base station Control apparatus is provided with a maximum interference amount instruction section for instructing the maximum amount of interference the interference amount must not exceed as a result of the scheduling in the base station.

  Thereby, the effect that the efficient data communication according to the fluctuation | variation of the noise rise accompanying the fluctuation | variation of the communication load between a base station and a mobile communication terminal is realizable is acquired.

Hereinafter, in order to explain 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 a diagram schematically showing a configuration of a mobile communication system according to Embodiment 1 of the present invention. The mobile communication system 1 includes a mobile communication terminal 2, a base station control device 3, and base stations 4a and 4b used by a user. The base station control device 3 relays these packet communications by being interposed between a network side configuration such as a public line network and the base stations 4a and 4b.

Thus, the system 1 has a configuration in which the base station controller 3 bundles a plurality of base stations 4a and 4b with respect to the network side. Thereby, in the system 1, it is possible to establish a radio link between the plurality of base stations 4a and 4b with respect to one terminal 2 called soft handover.
When the mobile communication system 1 is realized by a W-CDMA (Wideband-Code Division Multiple Access) system, the mobile communication terminal 2 is a UE (User Equipment), the base station controller 3 is an RNC (Radio Network Controller), a base The stations 4a and 4b may be referred to as Node-B.

  In particular, in high-speed uplink packet communication, a specific base station may be responsible for scheduling related to data communication for a certain terminal. The base station in this case may be called a serving cell for distinction. Furthermore, the base station as a whole is also referred to as a cell including a specific area in which the base station performs communication processing. In the description to be described later, these terms are used as appropriate.

FIG. 2 is a diagram showing a channel configuration in the mobile communication system according to the first embodiment. As an example, a channel configuration in a radio section between the base stations 4a and 4b and the terminal 2 in the W-CDMA system is shown. Yes.
In addition, the channel of this figure shows an example to the last, and is not limited to this. In addition, as a method of actually using a channel, a plurality of control channels can be combined with one channel.

First, the downlink channel from the base stations 4a and 4b to the terminal 2 will be described. CPICH (Common Pilot Channel) for reporting all timing references to components in the cell, and other broadcast information to the terminal 2 There is a P-CCPCH (Primary-Common Control Physical Channel) which is a physical channel for BCH (Broadcast channel).
Further, the downlink channel is used for uplink packet communication, DL-SACCH (Downlink Scheduling Assignment Control Channel) for notifying the allocation position by the scheduler for transmission of control information, base There is a DL-ACK / NACK-CCH (Downlink Ack / Nack Control Channel) for notifying the success / failure of reception of the stations 4a and 4b. Furthermore, there is FACH (Forward Access Channel) as a downlink common channel.

Next, the uplink channel from the terminal 2 to the base stations 4a and 4b will be described. As an uplink channel communication, UL-SICCH (Uplink Scheduling Information Control) that notifies the presence / absence of transmission data of the terminal 2 is used. Channel), UL-TFRI-CCH (Uplink TFRI Control Channel) for notifying the base station 4a, 4b of the modulation scheme and coding rate selected by the terminal 2, and EUTDTCH for transferring user data in uplink packet communication (Enhanced Uplink Dedicated Transport Channel) exists. Further, there is RACH (Random Access Channel) as an uplink common channel.
In addition, as a channel set for both uplink and downlink communication, there is a DPCH (Dedicated Physical channel) individually set for communication with a specific terminal, for communication such as voice and data and higher layer signaling. Used for The DPCH is sometimes referred to as a DPDCH (Dedicated Physical Data channel) for transferring data and a DPCCH (Dedicated Physical Control channel) for transferring bits related to control.

  3A and 3B are diagrams for explaining communication modes in wireless multiple data mode communication between a terminal and a base station in the mobile communication system according to Embodiment 1. FIG. As shown in FIG. 3A, in the data transmission process in the autonomous mode, first, an allowable rate is designated in advance from the base stations (Node-B) 4 a and 4 b to the terminal (UE) 2. At this time, the UE transmits data to the Node-B at an arbitrary time within the range of the permissible rate. When receiving data from the UE, the Node-B transmits a response signal (ACK / NACK) to the UE.

In the autonomous mode, it is not always necessary to specify the permissible rate in advance for each packet transmission, and basically a one-way communication process consisting of data transmission and its response is sufficient.
For this reason, the autonomous mode has the advantage that there is little delay because there is little signaling waste and the UE can freely transmit data when it wants to transmit.
On the other hand, a disadvantage of the autonomous mode is that a noise rise margin necessary for the amount of interference that may occur during data transmission must always be secured so that transmission can be performed at an arbitrary time.

  On the other hand, in the data transmission process in the scheduling mode, as shown in FIG. 3B, first, information such as the UE buffer state is transmitted from the UE to the Node-B. Upon reception of the information, the Node-B schedules uplink packets with a plurality of UEs, and assigns a transmission permission time (subframe) and a transmission rate to the UE that should be allowed to transmit data. The UE transmits a packet to Node-B according to the assignment, and receives a response signal from Node-B.

The merit of the scheduling mode is that there is no need to set an extra noise rise margin because there is no data transmission from a UE not assigned by the scheduler.
On the other hand, the disadvantage is that at least two round-trip communication processing consisting of communication processing required for scheduling and data body transmission processing is necessary, and a delay is unavoidably caused.
In addition, since signaling that notifies the Node-B of the presence / absence of transmission data of the UE must be performed in advance, when the capacity of the transmission data is small with respect to the number of times of signaling, the efficiency is deteriorated.

In the autonomous mode, there is no designation of transmission timing from the base station, and the terminal autonomously determines the transmission timing. On the other hand, in the scheduling mode, the base station designates the transmission timing to the terminal, and the terminal transmits data according to the transmission timing.
Even in the scheduling mode, the data rate may be specified by the base station. For example, in the autonomous mode, the base station designates a transmission data rate for data transmission to the terminal, but in the scheduling mode, the base station designates the transmission timing and the transmission data rate to the terminal and controls data transmission from the terminal. There is a case.

FIG. 4 is a diagram for explaining a threshold (threshold value) of a transmission data buffer serving as a reference for switching the communication mode of the mobile communication terminal according to the first embodiment. Here, the mobile communication terminal 2 operates in the autonomous mode in a state where transmission data is accumulated by a capacity equal to or less than the threshold of the transmission data buffer, and shifts to the scheduling mode when transmission data having a capacity exceeding the threshold is accumulated. Operate.
As described above, in the terminal 2, the autonomous mode and the scheduling mode are switched on the basis of the threshold relating to the accumulated amount of transmission data in the transmission data buffer. The determination of the threshold will be described later.

FIG. 5 is a diagram showing an allowable margin for the amount of interference (hereinafter referred to as noise rise) due to each factor in the uplink signal to the base station according to the first embodiment. In general, in a CDMA system, a certain amount of interference is allowed for a received encoded signal. However, when the noise rise tolerance limit is exceeded, the amount of interference becomes larger than the signal even if despreading is performed, and the above signal is correctly set. It becomes impossible to demodulate.
For this reason, the capacity (base station) determines how noise rise is controlled within the range from the state where the ideal amount of interference is zero (bottom of noise rise) to the allowable limit of interference capable of demodulating the received signal. This is an important point in securing the number of terminals that can be accommodated.

  As shown in the figure, among noise rises at the base station end, noise rise caused by transmission in the scheduling mode and autonomous mode is performed by appropriately switching between these transmission modes in uplink packet communication, so that the margin for scheduling mode and the autonomous mode Can be controlled within the margin.

On the other hand, the noise rise caused by other than the scheduling mode and the autonomous mode cannot be controlled within the allowable margin by the uplink packet communication.
As a cause of such interference, for example, own cell interference approximated by the sum of desired signal powers from terminals in the own cell, and signals from terminals in the coverage area of other base stations reach and interfere. Other cell interference and thermal noise generated from a receiver in the base station.
Therefore, in order to efficiently use radio resources for uplink packet communication, it depends on how to adjust the range of noise rise by controlling the margin for scheduling mode and the margin for autonomous mode.

FIG. 6 is a diagram illustrating an example of distribution of the noise rise margin (allowable amount of interference) of the base station for the autonomous mode and the scheduling mode when a plurality of terminals use uplink packet communication in a cell. In the illustrated example, a case is shown in which the number of terminals accommodated in the cell is larger than that in the case of FIG. 8 described later.
As will be described in detail later, the base station according to Embodiment 1 has a certain range of margin determined by the base station controller 3 in consideration of QoS parameters such as delay, and the controllable noise rise margin shown in FIG. Is set as Of these noise rise margins, when taking an allowable margin for noise rise due to the autonomous mode, a large noise rise margin per terminal in the cell may be set.

At this time, since a certain range is defined as the entire noise rise margin, as shown in FIG. 6A, the noise rise due to the scheduling mode is set by the amount of noise rise margin per terminal. Tolerance margin (hatched part) must be reduced.
Therefore, in the case shown in FIG. 6A, if the number of terminals communicating in the scheduling mode in the cell increases, there is a possibility that noise rise caused by this cannot be controlled within the allowable margin.

On the other hand, if the noise rise margin for uplink packet communication per terminal in the cell is set to be small, as shown in FIG. 6B, the allowable margin for noise rise caused by the scheduling mode in the base station. Many (shaded portions) can be secured.
That is, when there are a large number of terminals communicating in the scheduling mode in the cell, it is necessary to reduce the allowable margin per terminal for noise rise caused by the autonomous mode as much as possible.

In uplink packet communication, if the amount of data transmitted at a time decreases, the transmission rate also decreases. At this time, since the terminal side lowers the transmission power required for data transmission, the noise rise in the received signal of the base station is also reduced.
Therefore, as shown in FIG. 6B, in order to reduce the allowable margin per terminal for the noise rise caused by the autonomous mode as much as possible, the noise rise itself caused by the autonomous mode is reduced, that is, as a low data rate. What is necessary is just to control so that communication by autonomous mode may be performed.

  Specifically, when the number of terminals accommodated in the cell is large, as shown in FIG. 7, the threshold for determining the communication mode switching of the transmission data buffer in each terminal is set low, and the amount of transmission data is low. It is desirable to switch from autonomous mode to scheduling mode when the range in data rate is exceeded.

  Next, as shown in FIG. 8, a case is considered where there are few terminals using uplink packet communication in the cell (7 in FIG. 6 but 2 in FIG. 8). In this case, even if a large number of noise rise margins per terminal is set in the base station, as shown in FIG. 8A, an allowable margin for the noise rise caused by the scheduling mode (a hatched portion) is sufficient. Can be secured.

Also, as shown in FIG. 8B, even if the noise rise margin per terminal is set to be small in the base station, the allowable margin for noise rise due to the scheduling mode is not so much as in FIG. There is no difference.
That is, when the number of terminals accommodated in the cell is small, it is possible to execute communication at a higher data rate even in the autonomous mode than in the case of FIG.

  Specifically, when the number of terminals accommodated in the cell is small, as shown in FIG. 9, the transmission data buffer communication mode switching determination threshold in each terminal is set high so that the high data rate can be achieved even in the autonomous mode. May be allowed to handle a large amount of data.

From the above, according to the traffic situation in communication between the terminal and the base station, for example, the number of terminals operating in the scheduling mode in the cell and its operating state, the schedule and operating state operating in the autonomous mode, the transmission data buffer in the terminal It can be seen that appropriately changing the threshold is desirable in order to realize high-quality communication with less interference.
In addition, considering that the autonomous mode has a communication characteristic that transmission delay is small, it is desirable that terminals having severe delay requirements communicate in the autonomous mode as much as possible when there is an allowance margin for allocating noise rise. .

  FIG. 10 is a block diagram showing the internal configuration of the base station in FIG. 1, and the basic operation of the base station will be described using this figure. In addition, in FIG. 10, in order to prevent the notation of the notation, simplified names are described for the names of the respective constituent parts to be described later, but those given the same reference numerals indicate the same constituent parts. .

First, processing common to general CDMA modulation / demodulation will be described.
Explaining the transmission operation, the modulation unit 5 in the base stations 4a and 4b is configured to transmit signals of channels (P-CCPCH, downlink DPDCH, FACH, CPICH, DL-SACCH, DL-ACK / NACK-CCH, downlink DPCCH, etc.). Are multiplied by the channelization code generated by the downlink channelization code generator 6, and then these signals are multiplexed.

Next, the modulation unit 5 performs spread spectrum processing by multiplying the multiplexed signal of each channel by the scrambling code generated by the downlink scrambling code generator 7.
A baseband signal that is a signal of each channel multiplexed by the modulation unit 5 is output to the frequency conversion unit 8. The frequency converter 8 raises the baseband signal to the carrier frequency and outputs it to the power amplifier 9. In the power amplifier 9, the signal input from the frequency converter 8 is amplified to a desired power by an internal power amplifier. The signal amplified by the power amplifying unit 9 is transmitted to the terminal 2 side via the antenna 10.
When the pilot signal generating unit 27 obtains a reference clock signal from the timing managing unit 26, the pilot signal used by the terminal 2 as a reference for demodulation processing is set in the CPICH and transmitted to the entire cell.

Next, the reception operation will be described. A weak signal received from the antenna 10 is input to the low noise amplification unit 11. The low noise amplification unit 11 amplifies the signal and outputs the amplified signal to the frequency conversion unit 12. The frequency converter 12 lowers the signal input from the low noise amplifier 11 to the frequency of the baseband signal.
The despreader 15 multiplies the baseband signal frequency-converted by the frequency converter 12 by the scrambling code generated by the uplink scrambling code generator 13 to perform despreading processing, and the signal component for each terminal Take out. The demodulator 30 separates the despread signal input from the despreader 15 into a signal of each channel by the channelization code generated by the uplink channelization code generator 14.

Next, an operation for obtaining power of signals and interference will be described.
First, the desired signal power measurement unit 16 obtains the desired signal power from the uplink DPCCH pilot signal from the despreader 15. On the other hand, the low noise amplification unit 11 obtains the total received power in which the desired wave and noise are mixed via the antenna 10.
The interference wave power measurement unit 17 subtracts the power of the desired wave obtained by the desired wave power measurement unit 16 from the total received power input via the low noise amplification unit 11, the frequency conversion unit 12, and the despreader 15. The power of the interference wave that is a noise component is obtained.

Next, the power of the desired wave and the interference wave is sent from the measuring units 16 and 17 to the uplink packet transmission management unit 24, respectively. In this way, the uplink packet transmission management unit 24 acquires the power of the desired signal from each terminal in the own cell.
In addition, the uplink packet transmission management unit (communication management unit) 24 acquires from the base station control device 3 the interference (noise rise) due to own cell interference, other cell interference, and thermal noise in the uplink packet communication.

  Here, interference other than the self-cell interference (other cell interference and thermal noise) cannot be separated from noise and signal because the code is unknown. For this reason, the uplink packet transmission management unit 24 obtains interference from the base station control device 3 as interference component power in which noise due to other cell interference and thermal noise is mixed, other than the own cell interference. The interference is a mixture of interference from other cells and thermal noise and cannot be distinguished. However, it is not necessary to distinguish in the interference amount control processing.

Subsequently, the uplink packet transmission management unit 24 subtracts the permissible margin for the own cell interference and the interference component mixed with other cell interference and thermal noise from the permissible margin within a certain range based on the jamming margin. Get a controllable noise rise margin.
The jamming margin is an index indicating the maximum allowable capacity (number of terminals), and is defined by the ratio J / S of the signal power S to the interference component power J. The capacity (number of terminals) in the cell can be obtained from the jamming margin.
The accommodation capacity indicates how many terminals can be accommodated in a cell of the base station except for a terminal currently communicating with a certain base station.

  The jamming margin is calculated according to the following relational expression, for example, by a radio resource management unit in the base station control device 3 to be described later.

First, assuming that the received signal power at the base station is S (W) and the transmission rate of communication data is R (bit / sec), the power Eb per signal bit is expressed by the following equation (1).
Eb = S / R (1)
Here, S is the power of the signal from the mobile communication terminal 2 received by the base station, and is received at an equal level at the base station end by the high-speed power control function (inner loop) based on the CDMA TPC command. Assume that In W-CDMA, S can be obtained by the strength of the pilot signal, and R can be obtained by an instruction such as TFCI.

但し、Ｎ（個）は自セル内の最大端末数であり、自端末以外の端末を想定している。Ｓｉは基地局が受信した、第１番目から第（Ｎ−１）番目までの端末２からの信号の電力であり、添え字ｉは１から（Ｎ−１）までの正の整数である。また、Ｒｉは第１番目から第（Ｎ−１）番目までの端末２による通信データの伝送速度（ｂｉｔ／秒）である。 Next, the power Io (W) corresponding to interference from other terminals in the own cell can be expressed by, for example, the following formula (2).

However, N (number) is the maximum number of terminals in the own cell, and terminals other than the own terminal are assumed. Si is the power of the signal from the first to (N−1) th terminals 2 received by the base station, and the subscript i is a positive integer from 1 to (N−1). Ri is a transmission rate (bit / second) of communication data by the first to (N−1) th terminals 2.

  Thereby, Io is represented by the sum of the signal powers of the number of terminals obtained by subtracting 1 from the maximum number of terminals N. In the above equation (2), it is assumed that the signal power and the transmission rate of each terminal 2 are the same S and R, respectively.

Since it is inconvenient to distinguish and handle noise for each band width, the interference components due to interference from other cells and thermal noise are not distinguished as described above, and the average noise power spectral density converted to noise energy per 1 Hz. Treat as No (W).
When the spectrum band of the spread spectrum signal is W (Hz) and the power of the narrowband interference noise is J (W), noise rise (no interference) due to own cell interference, other cell interference and thermal noise (No + Io) is Can be represented by the following formula.
No + Io = J / W (3)

Here, SIR (Signal-to-Interference Ratio) is obtained from Eb / (No + Io), which is the ratio of the energy Eb per signal bit to the sum of noise rise due to thermal noise, other cell interference, and own cell interference. be able to.
SIR can be expressed as the following formula (4) using the above formula (1) and the above formula (3).
Eb / (No + Io) = S · W / (J · R) (4)

When the above formula (4) is modified to obtain the limit jamming margin (jamming margin) J / S that can be demodulated by CDMA, the following formula (5) is obtained.
J / S = (W / R) / {Eb / (No + Io)} (5)

In the base station control device 3, the jamming margin further includes a margin for interference in consideration of QoS parameters such as the operating state of the cells other than the target base station managed by itself, the traffic status of the cell of the target base station, and delay. A certain range of permissible margin (margin obtained by subtracting the margin for interference taking into account QoS parameters such as the operational status of other cells, the traffic status of the cell of the target base station, the delay, etc.) from the jamming margin is reported to the target base station. .
The target base station executes noise rise control by switching the communication mode within the allowable margin notified from the base station control device 3.
In this way, the jamming margin, which is the limit at which the base station is able to demodulate the amount of interference in the received signal even if it performs the above control, is affected by the communication status of the own station due to the operating state of other cells other than the own station Can be prevented. Details of this processing will be described later.

  The uplink packet transmission management unit 24 in the target base station is the remainder obtained by subtracting the allowable margin for the noise rise due to thermal noise, other cell interference, and own cell interference (uncontrolled margin shown in FIG. 5) from the above-mentioned allowable range margin. This margin is used as the controllable noise rise margin shown in FIG.

Further, assuming that the jamming power J is that the signal power from all terminals in the own cell is constant at S and the jamming power J (W) is caused by interference from other terminals other than the target terminal, It can be expressed as the following formula (6).
J = (N−1) S (6)

The following equation (7) can be derived from the above equations (5) and (6).
(N-1) = (W / R) / {Eb / (No + Io)} (7)

In the above formula (7), (N−1) corresponds to the maximum number of terminals that can be accommodated in the own cell other than the target terminal. Here, when the transmission rate R of the communication data is increased, the jamming margin is reduced from the equation (5), and it can be seen from the equation (7) that the capacity of the terminal in the own cell is reduced.
Further, when the SIR between the target terminal and the base station increases, for example, even when the base station requests the target terminal for stronger transmission power in order to ensure the required BER (bit error rate), the above formula (5 ) Shows that the jamming margin decreases.

  Returning to the description of the operation of the base station, the channel quality measurement unit 18 obtains the power of the desired wave and the interference wave input from the desired wave power measurement unit 16 and the interference wave power measurement unit 17 and the base station control device 3 respectively. The signal-to-interference power ratio (SIR) is calculated using the power of the interference caused by the own cell interference, other cell interference, and thermal noise, and is output to the quality target comparison unit 19.

In the W-CDMA system, transmission power control of a terminal is executed based on a target SIR value called an outer loop. This target SIR value is preset in the quality target comparison unit 19.
The decoding unit 22 in the base station counts a block error rate (BLER) due to a CRC (Cyclic Redundancy Check) error in communication with the target terminal, and when the required BLER is not satisfied, the target SIR value of the quality target comparison unit 19 Change settings such as raising This is called outer loop power control.

On the other hand, the quality target comparison unit 19 compares the signal-to-interference power ratio (SIR) calculated by the channel quality measurement unit 18 with the target signal-to-interference ratio (target SIR value), and sends the result to the TPC generation unit 20. Notice.
When it is determined from the comparison result that the power of the desired signal in the received signal is weaker than the target signal, the TPC generation unit 20 gives an instruction to increase the transmission power to the downlink DPCCH as a TPC (Transmission Power Command) called an inner loop. Set and output to modulation section 5.
The downlink DPCCH signal from the TPC generation unit 20 is transmitted to the terminal 2 via the modulation unit 5, the frequency conversion unit 8, the power amplification unit 9, and the antenna 10 as described above.

  On the other hand, when it is determined from the comparison result of the quality target comparison unit 19 that the power of the desired signal is stronger than the target signal, the TPC generation unit 20 sets an instruction to lower the transmission power as TPC and modulates the downlink DPCCH. Output to unit 5. The subsequent processing is the same. Such power control is called inner loop power control.

  In a CDMA system, increasing the strength of one signal is nothing but interference with other signals. For this reason, the signals to be transmitted and received are controlled so as to be within the necessary and sufficient signal power by executing the processing described above.

Next, a configuration necessary for uplink packet communication will be described.
First, the operation in the autonomous mode will be described.
In the operation in the autonomous mode, the base stations 4a and 4b transmit a transmission allowable margin to the terminal 2 in advance using a DL-SACCH or a similar downlink signaling channel. The transmission allowable margin is information that defines a communication condition necessary for the terminal 2 to demodulate the signal that the terminal 2 has performed uplink packet communication in the autonomous mode. For example, the maximum data rate allowed.
Thereafter, when a signal from the terminal 2 is received, the demodulator 30 separates the received signal into a signal of each channel in accordance with the above-described operation on the receiving side.

The TFRI receiving unit 21 includes UL-TFRI- in which a TFRI (Transport Format Resource Indicator) including a modulation parameter and a transport format selected by the terminal 2 among the signals of each channel separated by the demodulating unit 30 is set. A CCH signal is received.
The TFRI receiving unit 21 extracts the EUDTCH demodulation parameter from the UL-TFRI-CCH signal and sets it in the demodulating unit 30 and the decoding unit 22. The demodulator 30 demodulates the data body from the terminal 2 in the EUDTCH using the EUDTCH demodulation parameters, and outputs the demodulated data to the decoder 22. The decoding unit 22 decodes the data body from the terminal 2 in the EUDTCH using the EUDTCH demodulation parameter.

The response signal generator 23 determines whether the packet data transmitted from the terminal 2 has been correctly received on the base stations 4a and 4b side using the decoding result obtained by the decoder 22.
Here, when the reception is successful, the response signal generation unit 23 generates an ACK notifying successful reception, sets it to DL-ACK / NACK-CCH, and notifies the terminal 2 according to the transmission operation described above. On the contrary, when there is an error in the data from the terminal 2, the response signal generating unit 23 generates a NACK notifying the reception failure and notifies the terminal 2 in the same manner.

Next, the operation in the scheduling mode will be described.
In the operation in the scheduling mode, the transmission buffer amount reception unit 31 receives the UL-SICH signal from the demodulation unit 30, acquires information about transmission data in the terminal 2 in the scheduling mode, and notifies the uplink packet transmission management unit 24 To do.

The uplink packet transmission management unit 24 obtains subframe timing from the timing management unit 26, and comprehensively determines the amount of data accumulated in the transmission data buffer of each terminal in the own cell, the transmission power margin of the terminal, and the like. To determine the packet transmission timing.
The packet transmission timing determined by the uplink packet transmission management unit 24 is notified to the transmission rate / timing designation information transmission unit 25. The transmission rate / timing designation information transmission unit 25 sets a subframe or transmission rate for which transmission is permitted to DL-SACCH, and transmits it to the terminal 2 in accordance with the transmission operation described above.
Thereafter, when a signal from the terminal 2 is received, the demodulator 30 separates the received signal into a signal of each channel in accordance with the above-described operation on the receiving side.

The TFRI receiving unit 21 receives the UL-TFRI-CCH signal in which the TFRI is set in the subframe in which transmission permission is designated from the terminal 2 among the signals of each channel separated by the demodulating unit 30.
Next, the TFRI receiving unit 21 extracts the EUDTCH demodulation parameter from the UL-TFRI-CCH signal, and sets it in the demodulation unit 30 and the decoding unit 22. The demodulator 30 demodulates the data body from the terminal 2 in the EUDTCH using the EUDTCH demodulation parameters, and outputs the demodulated data to the decoder 22. The decoding unit 22 decodes the data body from the terminal 2 in the EUDTCH using the EUDTCH demodulation parameter.

  The response signal generator 23 generates an ACK as described above when the packet transmitted from the terminal 2 is correctly received on the base station side, generates a NACK in the case of an error, and outputs this as a DL-ACK. / NACK-CCH is set and notified to the terminal 2.

Next, a configuration for performing signaling for changing the threshold for switching the communication mode of the transmission data buffer will be described.
First, when notifying (signaling) the change of the threshold to the terminals 2 in the own cell all at once, the change is judged by the uplink packet transmission management unit 24 in the base station in consideration of the traffic situation in the own cell. The base station control device 3 is notified of this.

The base station control device 3 generates information about the threshold (information about which threshold is to be changed) in consideration of the operating status of other base stations other than the base station that issued the notification, and broadcasts the information. Insert it into the information and send it to the base station.
The broadcast information transmitting unit 28 in the base station receives a set of broadcast information in which information on the threshold is inserted from the base station control device 3 side, sets the broadcast information to P-CCPCH (BCH), and transmits the information described above. Transmit to the terminal 2 according to the operation. Note that the broadcast information is rarely set to another channel.

When the threshold is specified for each terminal 2, the change is determined by the uplink packet transmission management unit 24 in the base station that accommodates the terminal 2 in the cell in consideration of the traffic situation in communication with the terminal 2. The base station control device 3 is notified of this.
The base station control device 3 generates information on the threshold (information such as what value the threshold is changed to) in consideration of the operating status of other base stations other than the base station that issued the notification, and the message As an individual channel and transmitted to the base station.

When the downlink dedicated channel transmission unit 29 in the base station obtains the message about the threshold from the dedicated channel, the message is set to the downlink DPDCH (DPCH) and transmitted to the terminal 2 whose threshold is to be changed according to the transmission operation described above. . If there is a response message to this, it is received by the uplink dedicated channel receiver 32.
In addition, when the dedicated channel is released in communication with the terminal 2, information regarding the threshold may be set in the common channel.

When the base station control device 3 determines that the dedicated channel is released from the radio resource management information, the base station control device 3 sets the information about the threshold as a message to the common channel and transmits it to the base station.
When the downlink common channel transmission unit 34 in the base station obtains a message regarding the threshold from the common channel, the downlink common channel transmission unit 34 sets the message to FACH and transmits the message to the terminal 2 whose threshold is to be changed according to the transmission operation described above. If there is a response message to this, the uplink common channel receiving unit 33 receives it.

In the above description, the configuration in which the threshold change is determined on the base station side has been described, but the transmission mode itself set in the terminal 2 may be determined on the base station side.
In this case, in the above-described signaling operation for changing the threshold, information specifying the transmission mode to be set in the terminal 2 is transmitted to the terminal 2 instead of information regarding the threshold. Details of this processing will be described later.

  FIG. 11 is a block diagram showing the internal configuration of the mobile communication terminal in FIG. 1, and the basic operation of the mobile communication terminal will be described using this figure. In FIG. 11, in order to prevent redundancy of the notation, simplified names are given for the names of the respective constituent parts described later, but those given the same reference numerals indicate the same constituent parts. .

First, processing common to general CDMA modulation / demodulation will be described.
Explaining the transmission operation, the modulation unit 35 generates a channelization code generated by the uplink channelization code generator 36 for the signal of each channel (UL-SICCH, UL-TFRI-CCH, FACH, uplink DPCH, etc.). After being multiplied, these signals are multiplexed. Next, the modulation unit 35 performs a spread spectrum process by multiplying the signal obtained by multiplexing the signals of each channel by the scrambling code generated by the uplink scrambling code generator 37.

A baseband signal that is a signal of each channel multiplexed by the modulation unit 5 is output to the frequency conversion unit 38. The frequency converter 38 raises the baseband signal to the carrier frequency and outputs it to the power amplifier 39.
In the power amplifier 39, the signal input from the frequency converter 38 is amplified to a desired power by an internal power amplifier. The signal amplified by the power amplifying unit 39 is transmitted to the base stations 4a and 4b via the antenna 40.

Next, the reception operation will be described. A weak signal received from the antenna 40 is input to the low noise amplifier 41. The low noise amplifier 41 amplifies the signal and outputs the amplified signal to the frequency converter 42. The frequency converter 42 lowers the signal input from the low noise amplifier 41 to the frequency of the baseband signal.
The despreading demodulator 46 multiplies the baseband signal frequency-converted by the frequency converter 42 by the scrambling code generated by the downlink scrambling code generator 45 to perform a despreading process, and the downlink channelization code generator 44 The signal is separated into the signals of each channel by the channelization code generated in (1).

Thereafter, the despreading demodulation unit 46 outputs the TPC command in the signal received from the base station to the power control unit 43. The power control unit 43 instructs the power amplification unit 39 to increase or decrease the transmission power according to the TPC command, and the transmission power according to the instruction is set by the power amplification unit 39.
In addition, the CPICH signal among the signals of each channel separated by the despreading demodulation unit 46 is received by the common pilot signal receiving unit 47.

  The common pilot signal receiving unit 47 matches the timing in demodulation with the base station and supplies the timing to the timing management unit 48 as a timing signal. In the timing management unit 48, the timing signal supplied from the common pilot signal receiving unit 47 is distributed to each processing unit in the mobile communication terminal 2, and processing synchronized with the base station is executed.

Next, a configuration necessary for uplink packet communication will be described.
First, the operation in the autonomous mode will be described.
In the operation in the autonomous mode, the transmission permission information receiving unit 49 in the mobile communication terminal 2 receives a transmission allowable margin from the base station in advance using a DL-SACCH or a similar downlink signaling channel. This transmission allowable margin is notified from the transmission permission information receiving unit 49 to the uplink packet transmission management unit 51. Note that the transmission timing is arbitrary in the autonomous mode.
Thereafter, when the user sets data to be transmitted from the mobile communication terminal 2 to the base station, the transmission data is stored in the transmission data buffer 58 for uplink packet communication.

Since the transmission starts immediately in the autonomous mode, the uplink packet transmission management unit (communication management unit) 51 designates a TFRI corresponding to the transmission data amount in consideration of the transmission allowable margin and notifies the TFRI transmission processing unit 53 of it. .
The TFRI transmission processing unit 53 sets the TFRI in UL-TFRI-CCH and transmits it to the base station according to the transmission operation described above. Thus, the transmission operation is controlled so that noise rise is suppressed within the transmission allowable margin range designated by the base station.

The EUDTCH transmission processing unit 52 converts the data stored in the uplink packet communication transmission data buffer 58 into a transmission format specified by the TFRI, sets the data body in the EUDTCH, and sets the base in accordance with the transmission operation described above. Send to the station.
When the base station receives the packet data from the mobile communication terminal 2, the base station sets a response signal corresponding to the packet data to DL-ACK / NACK-CCH and transmits it. The response signal receiving unit 57 in the mobile communication terminal 2 determines ACK / NACK from the received DL-ACK / NACK-CCH according to the reception operation described above.

  When the response signal receiving unit 57 determines ACK, the determination result is notified to the uplink transmission packet management unit 51. Thereafter, the uplink transmission packet management unit 51 proceeds to a process of transmitting data of the next packet to the base station.

  On the other hand, when it is determined as NACK, the uplink transmission packet management unit 51 proceeds to a process of retransmitting the data of the packet determined as NACK. Here, the EUDTCH transmission processing unit 52 retransmits data having redundancy such as incremental redundancy as necessary at the time of retransmission.

Next, the operation in the scheduling mode will be described.
In the operation in the scheduling mode, when the user sets data to be transmitted from the mobile communication terminal 2 to the base station, the transmission data is stored in the uplink packet communication transmission data buffer 58.
After that, the buffer status transmission unit 55 that has received an instruction from the uplink packet transmission management unit 51 sets the data amount of data to be transmitted to the base station, the transmission power margin of the terminal 2, and the like in the UL-SICCH. According to the transmission operation performed.

  When receiving the UL-SICCH signal, the base station considers the state of the transmission data buffer 58 of each terminal 2 accommodated in its own cell, and sets an appropriate transmission timing at which the signal from each terminal 2 does not interfere most. decide. Thereby, the base station sets a transmission permission instruction to each terminal 2 in the DL-SACCH at the timing, and transmits according to the transmission operation described above.

The transmission permission information receiving unit 49 in the mobile communication terminal 2 receives information such as the transmission rate and subframe timing permitted by the base station set in the DL-SACCH. This information is passed from the transmission permission information receiving unit 49 to the timing management unit 48 and the uplink packet transmission management unit 51.
The uplink packet transmission management unit 51 designates a TFRI corresponding to the transmission data amount and notifies the TFRI transmission processing unit 53 of it. The TFRI transmission processing unit 53 sets TFRI in UL-TFRI-CCH and transmits it to the base station according to the transmission operation described above.

The EUDTCH transmission processing unit 52 reads the data stored in the uplink packet communication transmission data buffer 58, converts the data into the transmission format specified by the TFRI transmitted by the TFRI transmission processing unit 53, and then stores the data body in the EUDTCH. Set and transmit to the base station according to the transmission operation described above.
When the base station receives the packet data from the mobile communication terminal 2, the base station sets a response signal corresponding to the packet data to DL-ACK / NACK-CCH and transmits it. The response signal receiving unit 57 in the mobile communication terminal 2 determines ACK / NACK from the received DL-ACK / NACK-CCH according to the reception operation described above.

When the response signal receiving unit 57 determines ACK, the determination result is notified to the uplink transmission packet management unit 51. Thereafter, the uplink transmission packet management unit 51 proceeds to a process of transmitting data of the next packet to the base station.
On the other hand, when it is determined as NACK, the uplink transmission packet management unit 51 proceeds to a process of retransmitting the data of the packet determined as NACK.
Here, the EUDTCH transmission processing unit 52 retransmits data having redundancy such as incremental redundancy as necessary at the time of retransmission.

Next, a configuration necessary for changing the transmission mode will be described.
First, the uplink packet transmission management unit 51 compares the threshold given from the threshold change unit 50 with the amount of data staying in the uplink packet communication transmission data buffer 58.

At this time, if the staying amount is larger than the threshold, the uplink packet transmission management unit 51 notifies the transmission mode switching unit 54 that the switching of the transmission mode is completed.
When the switching of the transmission mode by the transmission mode switching unit 54 is completed, the buffer status transmission unit 55 sets information indicating that the switching of the transmission mode is completed in UL-SICCH, and transmits it to the base station according to the transmission operation described above. To do.

The TFRI transmission processing unit 53 may set information indicating that the switching of the transmission mode is completed in the UL-TFRU-CCH and transmit the information to the base station. Further, the protocol processing unit 56 that has received the information indicating that the transmission mode has been switched from the transmission mode switching unit 54 notifies the uplink dedicated channel transmission unit 60 of the information.
Accordingly, the uplink dedicated channel transmission unit 60 may set information indicating that the transmission mode is switched to the uplink DPCH as a message and transmit the message to the base station. In this way, the mobile communication terminal 2 notifies the base station of the transmission mode switching using some channel.

Next, a configuration necessary for changing the threshold for switching the transmission mode will be described.
First, when notifying all of the threshold changes from the base station to the terminal 2, information about the threshold is inserted into broadcast information (BCH) from the base station to the mobile communication terminal 2.

The broadcast information receiving unit 61 in the mobile communication terminal 2 receives a set of broadcast information from the base station side according to the reception operation described above, and notifies the protocol processing unit 56 of the set. The protocol processing unit 56 interprets the content of the notification information.
At this time, if the protocol processing unit 56 interprets that the broadcast information is an instruction to change the threshold of the transmission data buffer 58 for uplink packet communication, the protocol processing unit 56 sets the threshold to be changed by the instruction in the threshold changing unit 50. .
Thereafter, the threshold change unit 50 notifies the uplink packet transmission management unit 51 of the changed threshold. Thereby, in the mobile communication terminal 2, the transmission mode is switched based on the changed threshold.

Next, a case where the threshold is switched using a layer 3 message will be described.
In this case, two channels, an individual channel and a common channel, can be considered.
First, threshold change using an individual channel will be described.

The dedicated channel is used when a threshold is designated for each terminal.
The dedicated channel (downlink DPCH) in which the message about the threshold transmitted from the downlink dedicated channel transmitting unit 29 in the base station is set is received by the downlink dedicated channel receiving unit 63 in the terminal 2 and notified to the protocol processing unit 56. The The protocol processing unit 56 interprets the contents of the individual channel.

At this time, if the message set in the dedicated channel is interpreted as an instruction to change the threshold, the protocol processing unit 56 sets the threshold to be changed by the message in the threshold changing unit 50. Thereafter, the threshold change unit 50 notifies the uplink packet transmission management unit 51 of the changed threshold.
Further, the uplink dedicated channel transmission unit 60 sets information indicating that the transmission mode has been switched to the uplink DPCH as a message and transmits the message to the base station.

A case where the threshold is switched using a common channel will be described.
The common channel is used when the individual channel is released and the threshold is designated for each individual terminal 2. In particular, the dedicated channel may be temporarily released due to low power consumption or the like, and in this case, the common channel is used.

The message set to the common channel (FACH) from the base station is received by the downlink common channel receiving unit 62 in accordance with the reception operation described above. Thereafter, the message is sent from the downlink common channel receiving unit 62 to the protocol processing unit 56. The protocol processing unit 56 interprets the content of the message.
At this time, when the protocol processing unit 56 interprets that the message set in the common channel is an instruction to change the threshold, the protocol changing unit 56 sets the threshold to be changed by the message in the threshold changing unit 50. Thereafter, the threshold change unit 50 notifies the uplink packet transmission management unit 51 of the changed threshold.
Further, the uplink common channel transmission unit 59 sets information indicating that the transmission mode is switched to the RACH as a message and transmits the message to the base station.

Next, a case where the threshold is switched using physical layer signaling will be described. In the physical layer signaling, information on the threshold is assigned to a bit in physical layer information for setting a communication condition of the physical layer between the mobile communication terminal 2 and the base station. This physical layer information is set to, for example, DL-SACCH.
The physical layer signaling is used when the threshold is specified for each individual terminal 2, and can be specified at a higher speed than the above-described case.

The transmission permission information receiving unit 49 receives an instruction for information on the physical layer embedded in the DL-SACCH from the base station, and notifies the protocol processing unit 56 of the instruction. The protocol processing unit 56 interprets the content of the information received by the transmission permission information receiving unit 49.
When the protocol processing unit 56 interprets that the information is an instruction to change the threshold, the protocol processing unit 56 sets the threshold to be changed by the information in the threshold changing unit 50. Thereafter, the threshold change unit 50 notifies the uplink packet transmission management unit 51 of the threshold changed by the information.

  FIG. 12 is a block diagram showing the internal configuration of the base station control apparatus in FIG. 1, and the basic operation of the base station control apparatus 3 will be described using this figure. In FIG. 12, in order to prevent redundancy of the notation, simplified names are given for the names of the constituent parts to be described later, but those given the same reference numerals indicate the same constituent parts. .

  The QoS parameter mapping unit 64 includes radio resources for satisfying QoS (Quality of Service) (for example, delay tolerance) specified for communication between the mobile communication terminal 2 and the base stations 4a and 4b. Select the relevant parameter. Parameters relating to this communication include, for example, a mode in an RLC (Radio Link Control) layer, a transport block size number in a physical layer, a CRC (Cyclic Redundancy Check) bit number, and the like.

  The congestion control unit 65 prevents the occurrence of congestion in communication between the mobile communication terminal 2 and the base station, restricts calls, and the like. The radio resource management unit 66 manages information and measurement data related to radio resources (for example, channel, power, code, etc.), and transmits management information to each base as necessary during communication between the mobile communication terminal 2 and the base station. Notify the station. The above-described jamming margin is calculated by the radio resource management unit 66.

  Further, the radio resource management unit (communication resource management unit) 66 sets an allowable margin in the base station by giving a margin to the jamming margin in consideration of a QoS parameter such as a delay. In the base station, an instruction to switch the communication mode of the terminal 2 in the own cell is executed so that the noise rise is within the permissible margin.

In the conventional mobile communication system, the communication conditions between the base station and the terminal such that the noise rise falls within the jamming margin are determined by the base station controller, and the base station is determined according to the communication conditions notified from the base station controller. Communication between the station and the terminal was controlled.
However, in this configuration, there is an inevitable problem that communication quality between the base station and the terminal is limited due to a communication delay between the base station controller and the base station.

Therefore, in the mobile communication system of the present invention, the allowable margin in which the base station control apparatus further has a margin for interference to be considered from a request based on QoS parameters such as an operating state and a delay other than the target cell with respect to the jamming margin. To the base station.
In other words, the allowable margin is narrower than the jamming margin by the amount of interference that should be considered from the request based on the QoS parameters such as the operating state and delay other than the target cell.

Then, the base station executes a part of the process for determining the communication condition such that the noise rise is within the allowable margin. For example, the base station appropriately executes margin distribution for noise rise in each mode within the allowable margin in accordance with the current communication status and the like.
As a result, the base station can quickly determine the communication condition according to the QoS of communication with the terminal without completely depending on the communication condition notified from the base station controller, and the communication load Efficient data communication according to the noise rise variation accompanying the variation becomes possible.

  The core network protocol processing unit 67 processes a protocol in communication with the network side. The wireless network protocol processing unit 68 processes a protocol in communication with the base station side.

Next, the operation of the mobile communication system according to the first embodiment will be described.
As described above, when the transmission data exceeding the communication mode switching threshold in the transmission data buffer in the mobile communication terminal 2 is accumulated, the scheduling mode is set, and when the transmission data is lower, the mode is switched to the autonomous mode. Hereinafter, three methods for performing signaling for changing the threshold will be described.

  In the first method, the threshold change information is set as broadcast information, and is simultaneously notified to the terminals 2 in the cell to be changed. In the second method, the threshold change information is set in an individual channel or a common channel, and is notified to each terminal 2 to be changed. Furthermore, the third method is to notify and change the threshold change information to each terminal 2 by physical layer signaling.

First, the first method will be described.
This method changes the threshold according to the number of terminals handling the scheduling mode in the current cell, the number of terminals handling the autonomous mode, the operating status of these and the operating status of the dedicated channel, thereby increasing the noise rise in the own cell. Can be adjusted to an appropriate amount.

  FIG. 13 is a diagram illustrating an example of distribution of the noise rise margin of the base station when the base station control apparatus according to the first embodiment determines the transmission mode switching threshold of the terminal according to the first method. FIG. 14 is a diagram for explaining the change of the transmission mode switching threshold according to the distribution of the noise rise margin shown in FIG. The basic concept of the first method will be described with reference to these drawings.

  First, it is assumed that a plurality of mobile communication terminals 2 are accommodated in a cell as a state before changing the transmission mode switching threshold. In addition, the noise rise margin in the base station includes an allowable margin for noise rise caused by the autonomous mode and the scheduling mode, and an allowable margin for noise rise caused by transmission on an individual channel (individual channels and other in the figure). It is assumed that (region) is distributed as shown in FIG.

Here, the noise rise margin in the base station is an allowable margin in which a margin for interference to be considered based on the operating state of other cells and QoS is further added to the above-described jamming margin.
Further, at this time, it is assumed that the threshold of the transmission data buffer of the mobile communication terminal 2 has the relationship shown in FIG. 14A with respect to the transmission data in the buffer.

It is assumed that data transmission on the dedicated channel has a certain amount of data transmission. At this time, management is performed by the base station control device 3 so as to ensure an allowable margin necessary for noise rise caused by transmission on the dedicated channel.
For this reason, when the frequency of data transmission through the dedicated channel increases between the terminal 2 and the base station, the base station control device 3 instructs the base station to increase the allowable margin required for data transmission through the dedicated channel.

  Further, data transmission through the dedicated channel is performed for each individual terminal 2. For this reason, when the frequency of data transmission through the dedicated channel increases, an allowable margin by the dedicated channel is secured from the allowable margin allocated to the individual terminals 2 out of the noise rise margin at the base station.

As a result, as shown in FIG. 13B, among the noise rise margins in the base station, the allowable margin assigned to the noise rise due to the autonomous mode is decreased by the increase of the allowable margin due to the dedicated channel. Will do. At this time, when the number of terminals is the same, the noise rise margin per terminal is reduced.
In this case, if a transmission mode switching threshold having a relatively small value as shown in FIG. 14A is set for the transmission data buffer, data transmission exceeding the allowable margin in the autonomous mode can be executed. There is sex.

That is, with the threshold as shown in FIG. 14A, noise rise due to the data transmission cannot be allowed for the terminal 2 trying to perform transmission with a large amount of data to the base station.
Therefore, when the noise rise margin distribution configuration as shown in FIG. 13B is adopted, as shown in FIG. 14B, the terminal 2 accommodated in the cell by the broadcast information in the first method. By simultaneously lowering the threshold value of the transmission data buffer, the terminal 2 that intends to perform data transmission with a large amount of data is changed from the autonomous mode to the scheduling mode.

At this time, in the terminal 2 that performs data transmission with a small amount of data, the autonomous mode is maintained as it is unless the transmission data amount exceeds the threshold value after the change.
Note that if the threshold is lowered too much at once, the balance between the number of terminals in the autonomous mode and the scheduling mode is lost, so it is desirable to gradually lower the threshold.

  FIG. 15 is a diagram showing a change sequence when changing the threshold of the transmission data buffer by the first method in the mobile communication system according to the first embodiment. The base station measures noise rise at the current base station end (step ST1). More specifically, as shown in FIG. 10, the desired signal power measurement unit 16 and the interference signal power measurement unit 17 in the base station measure the noise rise (interference amount) at the current base station end.

  Thereafter, the base station notifies the base station controller 3 of the noise rise measured in step ST1 (step ST2). Further, the base station notifies the base station control device 3 of the number of terminals operating in the autonomous mode and the scheduling mode within the own cell (step ST3).

  Next, the radio resource management unit 66 in the base station control device 3 operates the operating status (for example, in the cell of the neighboring base station) of the base stations (hereinafter referred to as neighboring base stations) existing around the target base station. Including the number of accommodated terminals) (step ST4).

  When a large number of terminals 2 are operating in the peripheral base station, there is a possibility that the terminal 2 moves in an area where handover is executed. In this case, the radio resource management unit 66 in the base station control device 3 further adds a margin considering noise rise due to handover to the jamming margin as an allowable margin notified to the base station.

  Subsequently, the radio resource management unit 66 acquires the operation status of the dedicated channel in the base station (step ST5). Usually, since the dedicated channel is used for data transmission from the neighboring base station to the terminal 2 in the soft handover, the base station control device 3 grasps the operation status.

  The radio resource management unit 66 determines whether or not the noise rise margin in the base station has a margin with respect to the current noise rise acquired in steps ST1 to ST5, or conversely, the margin is insufficient. (Step ST6). In response to this determination result, the radio resource management unit 66 proceeds to a process of changing the noise rise frame between the autonomous mode and the scheduling mode.

  Here, the noise rise frame refers to the assigned amount of noise rise margin assigned to each mode, distributed as the allowable margin specified by the base station control device 3 to the base station. In FIG. 13, for example, a hatched portion as a scheduling mode margin represents a noise rise frame for the scheduling mode.

  When the radio resource management unit 66 determines that the noise rise margin in the base station is excessive or insufficient with respect to the current noise rise, and the noise rise frame allocated in the base station needs to be changed, The station is instructed to change the noise rise frame in the autonomous mode and / or the scheduling mode (step ST7).

  On the other hand, when the radio resource management unit 66 determines that the noise rise margin in the base station is not excessive or insufficient with respect to the current noise rise and that the noise rise frame does not need to be changed, the radio resource management unit 66 instructs to change the noise rise frame. Do not do.

  When receiving the instruction to change the noise rise frame from the base station control device 3, the base station changes the noise rise frame in accordance with the instruction (step ST8). For example, when the frequency of data transmission through the dedicated channel increases as described with reference to FIG. 13, the base station control device 3 increases the noise rise frame of the dedicated channel in the noise rise margin in the base station, Instruct to reduce the noise rise frame for autonomous mode by the increment.

Next, when there is a notification from the base station that the transmission mode switching threshold of the terminal 2 should be changed, the radio resource management unit 66 considers the current traffic status, noise rise at the base station, and its allowable margin. Thus, it is determined to which value the threshold should be changed so as to obtain an appropriate amount of interference in communication between the base station and the terminal 2 (step ST9).
Thereafter, the radio resource management unit 66 instructs the base station to notify the base station of information regarding the threshold change including the threshold value of the determination result (step ST10).

The base station that has received information on the threshold change from the base station controller 3 sets information including the threshold value as broadcast information (BCH), and performs simultaneous transmission to each terminal 2 (step ST11). .
The terminal 2 that has received the notification information reads the value of the transmission mode switching threshold from the notification information and changes the threshold in the same manner as the operation described with reference to FIG. 11 (step ST12).

  The operation of step ST9 in FIG. 15 of the mobile communication system according to the first embodiment will be described in detail using the flowchart shown in FIG.

  First, the uplink packet transmission management unit 24 in the base station compares the data amount of the transmission data buffer reported from the terminal 2 in its own cell with the threshold value set in the terminal 2, and determines the threshold value. Determine if it should be changed. Thus, when it is determined that the threshold value should be changed, the base station notifies the base station control device 3 to that effect according to the transmission operation described above.

In step ST1a, the radio resource management unit 66 in the base station control device 3 that has received the notification that the threshold should be changed from the base station transmits data on the dedicated channel based on the operating status of the dedicated channel in the base station. Approximate noise rise due to.
Next, the radio resource management unit 66 approximates an allowable margin for noise rise according to the current operating state of the base station other than the base station (step ST2a). For example, when the number of terminals in the peripheral base station is large, there is a possibility that the terminal 2 moves in the area where the handover is executed. In this case, the radio resource management unit 66 approximates a margin in consideration of noise rise caused by handover.

When the margin in consideration of the operation state of the neighboring base station (for example, the margin in consideration of the case where the number of terminals in the neighboring base station is large) is obtained in this way, the radio resource management unit 66 sets the noise rise set in the base station. The margin is further provided for the allowable margin for.
That is, a margin obtained by subtracting a margin considering the operating state of the neighboring base station from the allowable margin is set as a new allowable margin to be set in the base station.

  Subsequently, the radio resource management unit 66 obtains the noise rise in the scheduling mode and the number of terminals in the cell of the base station (step ST3a). Thereafter, the radio resource management unit 66 accepts the noise rise caused by data transmission on the dedicated channel obtained in step ST1a and the noise rise of the scheduling mode in the cell of the base station obtained in step ST3a. Estimate the margin.

  In step ST4a, the radio resource management unit 66 determines the margin for the dedicated channel and the margin for the scheduling mode from the entire allowable margin of the base station that anticipates the margin according to the operating state of the neighboring base station in step ST2a. To obtain an allowable margin (noise rise frame) for noise rise in the autonomous mode in the base station.

Next, the radio resource manager 66 determines whether or not the number of terminals operating in the autonomous mode in the cell of the base station is appropriate for the noise rise frame of the autonomous mode in the base station obtained in step ST4a. Determination is made (step ST5a).
The base station reports the amount of transmission data in the transmission data buffer from each terminal 2 in its own cell. Further, the base station control device 3 receives the transmission data amount notification from the base station. The radio resource management unit 66 in the base station control device 3 calculates in advance an average value in a predetermined period for the transmission data amount of the terminal 2 notified from the base station.

  In addition, the radio resource management unit 66 exceeds the noise rise frame with respect to the base station as long as there is an autonomous mode noise rise frame in the base station with respect to the average value of the transmission data amount of the terminal 2. It is statistically determined in advance how many percent of terminals that transmit data that cannot be demodulated occur with respect to the total number of terminals.

  Here, for example, when the number of terminals that transmit data that cannot be demodulated exceeding the noise rise frame in the autonomous mode exceeds a predetermined ratio with respect to the total number of terminals, the number of terminals in the autonomous mode is too large. A case where the ratio is less than or equal to the ratio is defined as a state where the number of terminals in the autonomous mode is too small, and a case other than these is defined as a state where the number of terminals in the autonomous mode is appropriate.

In step ST5a, the radio resource management unit 66 checks how much the noise rise frame of the autonomous mode in the current base station is with respect to the above average value, and whether the number of terminals in the autonomous mode is appropriate based on the result. Determine whether or not.
If it is determined in step ST5a that there are too many terminals in the autonomous mode, the radio resource management unit 66 decreases the value of the switching threshold currently set in the terminal 2 (step ST6a). The noise rise margin allocated to the autonomous mode terminal 2 is distributed according to the number of terminals within the autonomous mode noise rise frame in the base station.

Therefore, when the number of terminals in the autonomous mode increases, the noise rise frame itself in the autonomous mode in the base station is constant, so that the noise rise margin assigned to each terminal 2 in the autonomous mode decreases.
For this reason, if the noise rise margin allocated to each terminal 2 is reduced, if transmission is performed at a data rate corresponding to the transmission data amount, a terminal 2 that exceeds the noise rise in a demodulatable range occurs. In this way, a state in which the allowable margin within the demodulatable range exceeds the number of terminals provided is defined as a state in which the number of terminals in the autonomous mode in the cell is large.

  When the threshold value is decreased in step ST6a, the radio resource management unit 66 proceeds to the process of step ST10 in FIG. 15, and notifies the base station of the changed threshold value as information related to the threshold change.

  When determining that the number of terminals in the autonomous mode is appropriate in step ST5a, the radio resource management unit 66 maintains the current switching threshold value (step ST7a). This threshold value is instructed to be notified to the base station as information relating to the threshold change in step ST10 of FIG.

If it is determined in step ST5a that the number of autonomous mode terminals is too small, the radio resource management unit 66 increases the value of the switching threshold currently set in the terminal 2 (step ST8a). Here, the state in which the number of terminals in the autonomous mode is too small means that even if transmission is performed at a data rate corresponding to the amount of transmission data, there is a margin more than necessary for the noise rise margin allocated to each terminal 2. It is a state that ends up.
In this case, if the threshold value is increased to increase the number of terminals in the autonomous mode in the cell, the noise rise margin assigned to each terminal 2 can be used effectively.

In this way, when the threshold value is increased in step ST8a, the radio resource management unit 66 proceeds to the process of step ST10 in FIG. 15, and the base station uses the changed threshold value as information related to the threshold change. Inform the notification.
In step ST6a and step ST8a, if the threshold value increase / decrease performed at one time is too large, there is a possibility that more terminals 2 will switch the transmission mode than necessary.
Therefore, it is desirable that the threshold value increase / decrease performed at a time be suppressed to a constant value in consideration of the number of terminals in the autonomous mode in the cell and the threshold value is gradually changed.

  As described above, in the first method, the change of the transmission mode switching threshold can be notified all at once in the cell. For this reason, it is possible to reduce the number of occurrences of signaling for notifying the threshold change.

  The signaling using the broadcast information described above is disadvantageous in that it cannot be set for each terminal 2. Therefore, the terminal 2 in the cell may be configured to execute grouping based on, for example, a QoS class and set the threshold for each group.

A specific grouping method will be described.
In the W-CDMA system, four QoS classes (conversational class, streaming class, interactive class, and background class) are defined. For example, the terminals 2 in the cell are divided into the following three groups based on the communication delay tolerance for these QoS classes.

  The first group is a group that uses a communication service that handles data such as voice and moving images to which the delay class is tolerated most, to which a conversational class and a streaming class belong.

  The second group is a group that uses a communication service to which a certain delay is allowed, to which the interactive class belongs. For example, still images and text files provided on WWW (World Wide Web) and the like are handled. When transmitting these data, a communication delay is allowed to some extent, but it is not completely allowed, and if it becomes too slow, the user is uncomfortable.

  The third group is a group that uses a communication service to which a background class belongs and delay is allowed. For example, data transfer using FTP (File Transfer Protocol) that requires scheduling related to communication and delay is applicable.

  The grouping of the terminals 2 in the cell is executed by the QoS parameter mapping unit 64 in the base station control device 3 that knows the QoS class in communication with the base station. The grouping result is also held in the QoS parameter mapping unit 64.

Next, the threshold changing process for the terminals 2 grouped as described above will be described.
The radio resource management unit 66 in the base station control device 3 that has received the notification that the threshold should be changed from the base station should change the threshold based on the grouping result held in the QoS parameter mapping unit 64. It is determined to which group the terminal 2 belongs.

The radio resource management unit 66 determines the range of increase / decrease of the threshold value set for each group based on the determination result of grouping. For example, control is performed so that the largest threshold value is set for the terminals 2 in the first group that does not allow delay most. Further, control is performed so that the smallest threshold value is set for the terminals 2 in the third group in which the delay is allowed.
In this way, for example, in the first group that tolerates the least delay, mode switching is performed so that the autonomous mode in which the delay does not occur most is obtained.

In the first group, when the number of terminals in the autonomous mode increases and the noise rise frame in the scheduling mode is insufficient, the threshold value is gradually decreased so that the terminal 2 having a large amount of transmission data is switched to the scheduling mode. You may control.
In addition, for the second group and the third group in which the delay is allowed, a lower threshold is set as compared with the first group so that the switching to the scheduling mode is performed.

However, if the number of terminals belonging to the first group in the cell is small and the allowable margin in the base station is sufficient, the second group and the third group can be used to effectively use the allowable margin. You may control to raise the value of the threshold to set.
Further, when the terminals 2 in the cell almost belong to the first group, the grouping is further subdivided based on the delay amount indicating how much delay the data handled by the terminal 2 allows. Also good.

Next, the second method will be described.
In this method, the transmission mode switching threshold change information is set in a layer 3 message such as an individual channel or a common channel, whereby the transmission mode most suitable for each terminal can be switched.

  FIG. 17 is a diagram showing an example of distribution of the noise rise margin of the base station when the base station control apparatus according to the first embodiment determines the transmission mode switching threshold of the terminal according to the second method. FIG. 18 is a diagram for explaining the change of the transmission mode switching threshold according to the distribution of the noise rise margin shown in FIG. The basic concept in the second method will be described with reference to these drawings.

  First, it is assumed that a plurality of mobile communication terminals 2 are accommodated in a cell as a state before changing the transmission mode switching threshold. In addition, the noise rise margin in the base station includes an allowable margin for noise rise caused by the autonomous mode and the scheduling mode, and an allowable margin for noise rise caused by transmission on an individual channel (individual channels and other in the figure). It is assumed that (region) is distributed as shown in FIG.

Here, the noise rise margin in the base station is an allowable margin in which the above-mentioned jamming margin is further provided with a margin for interference to be taken into consideration due to the operating state of other cells and QoS.
At this time, it is assumed that the above-mentioned threshold of the transmission data buffer of the mobile communication terminal 2 has a relationship shown in FIG. 18A with respect to the transmission data in the buffer.

It is assumed that data transmission on the dedicated channel has a certain amount of data transmission. At this time, management is performed by the base station control device 3 so as to ensure an allowable margin necessary for noise rise caused by transmission on the dedicated channel.
For this reason, when the frequency of data transmission through the dedicated channel increases between the terminal 2 and the base station, the base station control device 3 instructs the base station to increase the allowable margin required for data transmission through the dedicated channel.

Further, data transmission through the dedicated channel is performed for each individual terminal 2. For this reason, when the frequency of data transmission through the dedicated channel increases, an allowable margin by the dedicated channel is secured from the allowable margin allocated to the individual terminals 2 out of the noise rise margin at the base station.
As a result, as shown in FIG. 17B, among the noise rise margins in the base station, the allowable margin for noise rise due to the autonomous mode is reduced by the amount of increase in the allowable margin due to the dedicated channel. .

In this case, if the transmission mode switching threshold value shown in FIG. 18A is set for the transmission data buffer, data transmission exceeding the allowable margin in the autonomous mode may be executed. .
That is, with the threshold as shown in FIG. 18A, the noise rise due to the data transmission cannot be allowed for the terminal 2 that intends to perform transmission with a large amount of data to the base station.

  For this reason, as shown in FIGS. 18B and 18C, it is necessary to lower the switching threshold value. However, when lowering the switching threshold value, the request for communication quality for each terminal 2 should be considered. For example, whether or not to allow delay differs depending on the nature of data handled by each terminal 2.

  In the QoS classification of communication services in the W-CDMA system, in a conversational class that handles data such as voice and a streaming class that handles data such as video, the real time is used to prevent delays from giving an unnatural perception to the user. Sex is required. Therefore, in these QoS classes, it is necessary to reduce the delay as much as possible.

  On the other hand, in an interactive class that handles Web data or a background class that handles data transfer using FTP or the like, the accuracy of transmitted data is required, but delay is rarely perceived by the user. For this reason, these data transmissions are handled on a best effort basis, and even if there is a delay, the problem is small.

Therefore, by executing threshold change for each terminal 2 using the second method, for the terminal 2 that handles data that does not allow delay, as shown in FIG. The amount of decrease in the threshold value of the buffer is made small so that the threshold does not drop so much.
On the other hand, for the terminal 2 that handles data that can tolerate delay, as shown in FIG. 18 (c), the threshold value of the transmission data buffer is increased more than in the case of FIG. 18 (b). Reduce the threshold.
In this way, the terminal 2 that handles data that does not allow delay maintains an autonomous mode that has communication characteristics that are unlikely to cause delay, and only the terminal 2 that handles data that allows delay is guided from the autonomous mode to the scheduling mode. Is done.

At this time, as shown in FIG. 17 (b), in the allowable margin of the autonomous mode in the base station, the margin of the allowable margin of the terminal 2 that handles data that does not allow delay (noise margin for one terminal that does not allow delay). The reduction in the margin is reduced, and the margin reduction of the allowable margin of the terminal 2 that handles data that can tolerate the delay (noise margin for one terminal that allows delay) is increased.
Note that if the threshold is lowered too much at once, the balance between the number of terminals in the autonomous mode and the scheduling mode is lost, so it is desirable to gradually lower the threshold.

  FIG. 19 is a diagram showing a change sequence in the case where the transmission data buffer threshold is changed by the second method in the mobile communication system according to the first embodiment. The base station measures noise rise at the current base station end (step ST1b). More specifically, as shown in FIG. 10, the desired signal power measurement unit 16 and the interference signal power measurement unit 17 in the base station measure the noise rise (interference amount) at the current base station end.

Thereafter, the base station notifies the base station controller 3 of the noise rise measured in step ST1b (step ST2b). Further, the base station notifies the base station control device 3 of the number of terminals operating in the autonomous mode and scheduling mode in its own cell (step ST3b).
Next, the radio resource management unit 66 in the base station control device 3 acquires the operating status of the neighboring base station (for example, including the number of accommodated terminals in the cell of the neighboring base station) (step ST4b).

  When a large number of terminals 2 are operating in the peripheral base station, there is a possibility that the terminal 2 moves in an area where handover is executed. In this case, the radio resource management unit 66 in the base station control device 3 further adds a margin considering noise rise due to handover to the jamming margin as an allowable margin notified to the base station.

  Subsequently, the radio resource management unit 66 acquires the operation status of the dedicated channel in the base station (step ST5b). Usually, since the dedicated channel is used for data transmission from the neighboring base station to the terminal 2 in the soft handover, the base station control device 3 grasps the operation status.

  The radio resource management unit 66 determines whether the noise rise margin at the base station has a margin with respect to the current noise rise acquired in steps ST1b to ST5b, or conversely, whether the margin is insufficient. (Step ST6b). In response to this determination result, the radio resource management unit 66 proceeds to a process of changing the noise rise frame between the autonomous mode and the scheduling mode.

  When the radio resource management unit 66 determines that the noise rise margin in the base station is excessive or insufficient with respect to the current noise rise, and the noise rise frame allocated in the base station needs to be changed, The station is instructed to change the noise rise frame in the autonomous mode and / or the scheduling mode (step ST7b).

  On the other hand, when the radio resource management unit 66 determines that the noise rise margin in the base station is not excessive or insufficient with respect to the current noise rise and that the noise rise frame does not need to be changed, the radio resource management unit 66 instructs to change the noise rise frame. Do not do.

  When receiving the instruction for changing the noise rise frame from the base station control device 3, the base station changes the noise rise frame in accordance with the instruction (step ST8b). For example, when the frequency of data transmission through the dedicated channel increases as described with reference to FIG. 17, the base station control device 3 increases the noise rise frame of the dedicated channel in the noise rise margin in the base station, and this increase Instruct to reduce the noise rise frame for autonomous mode.

Next, when there is a notification from the base station that the transmission mode switching threshold of the terminal 2 should be changed, the radio resource management unit 66 considers the current traffic status, noise rise at the base station, and its allowable margin. Thus, it is determined to which value the switching threshold for each terminal 2 should be changed (step ST9b).
Thereafter, the radio resource management unit 66 transmits information on the threshold change including the threshold value of the determination result to the base station as a layer 3 message (step ST10b).

  The base station that has received information on the threshold change from the base station control device 3 uses the dedicated channel (DPCH) when communication with the terminal 2 to be set for the threshold is established on the dedicated channel (DPCH). If the communication on the dedicated channel is not established, the above information is transmitted to the target terminal 2 using the common channel (FACH) (step ST11b).

The terminal 2 that has received the information reads the value of the transmission mode switching threshold from the information set for the individual channel or the common channel and changes the threshold in the same manner as the operation described with reference to FIG. 11 (step ST12b). .
After that, the uplink dedicated channel transmission unit 60 in the terminal 2 sets information indicating that the switching threshold value has been changed to the uplink DPCH or RACH as a message and transmits it to the base station (step ST13b). The base station that has received the message notifies the base station control device 3 that the change has been completed (step ST14b).

The operation at step ST9b in FIG. 19 of the mobile communication system according to the first embodiment will be described in detail using the flowchart shown in FIG.
First, the uplink packet transmission management unit 24 in the base station compares the data amount of the transmission data buffer reported from the terminal 2 in its own cell with the threshold value set in the terminal 2, and determines the threshold value. Determine if it should be changed. Accordingly, when it is determined that the threshold value should be changed, the base station notifies the base station control device 3 to that effect according to the transmission operation described above.

In step ST1c, the radio resource management unit 66 in the base station control device 3 that has received the notification that the threshold should be changed from the base station transmits data on the dedicated channel based on the operating status of the dedicated channel in the base station. Approximate noise rise due to.
Next, the radio resource management unit 66 approximates an allowable margin for noise rise according to the current operation state of the base station other than the base station (step ST2c). For example, when the number of terminals in the peripheral base station is large, there is a possibility that the terminal 2 moves in the area where the handover is executed. In this case, the radio resource management unit 66 approximates a margin in consideration of noise rise caused by handover.

When the margin in consideration of the operation state of the neighboring base station (for example, the margin in consideration of the case where the number of terminals in the neighboring base station is large) is obtained in this way, the radio resource management unit 66 sets the noise rise set in the base station. The margin is further provided for the allowable margin for.
That is, a margin obtained by subtracting a margin considering the operating state of the neighboring base station from the allowable margin is set as a new allowable margin to be set in the base station.

  Subsequently, the radio resource management unit 66 obtains the noise rise in the scheduling mode and the number of terminals in the cell of the base station (step ST3c). Thereafter, the radio resource management unit 66 accepts the noise rise caused by the data transmission on the dedicated channel obtained in step ST1c and the noise rise of the scheduling mode in the cell of the base station obtained in step ST3c. Estimate the margin.

  In step ST4c, the radio resource management unit 66 determines the margin for the dedicated channel and the margin for the scheduling mode from the entire allowable margin of the base station that anticipates the margin according to the operating state of the neighboring base stations in step ST2c. To obtain an allowable margin (noise rise frame) for noise rise in the autonomous mode in the base station.

At this time, when receiving a request for the transmission data rate from each terminal 2, the radio resource management unit 66 adjusts an allowable margin (allowable limit) for the scheduling mode in consideration of the request for the transmission data rate ( Step ST5c).
When the terminal 2 transmits data with the base station in the scheduling mode, the terminal 2 notifies the base station of the transmission data rate desired by itself. The uplink packet transmission management unit 24 in the base station manages the data communication schedule together with the transmission data rate desired from the terminal 2.

Further, the uplink packet transmission management unit 24 notifies the radio resource management unit 66 in the base station control device 3 of the transmission data rate desired by the terminal 2.
The radio resource management unit 66 estimates the noise rise corresponding to the transmission data rate of the terminal 2 operating in the scheduling mode within the own cell, obtains the allowable margin corresponding to the noise rise, and sets the allowable margin for the scheduling mode. Adjust.
After that, the radio resource management unit 66 adjusts the allowable margin for the autonomous mode obtained in step ST4c using the allowable margin for the scheduling mode adjusted as described above.

Next, the radio resource management unit 66 determines whether the number of terminals operating in the autonomous mode in the cell of the base station is appropriate for the noise rise frame of the autonomous mode in the base station obtained as described above. It is determined whether or not (step ST6c).
The base station reports the amount of transmission data in the transmission data buffer from each terminal 2 in its own cell. Further, the base station control device 3 receives the transmission data amount notification from the base station. The radio resource management unit 66 in the base station control device 3 calculates in advance an average value in a predetermined period for the transmission data amount of the terminal 2 notified from the base station.

In addition, the radio resource management unit 66 exceeds the noise rise frame with respect to the base station as long as there is an autonomous mode noise rise frame in the base station with respect to the average value of the transmission data amount of the terminal 2. It is statistically determined in advance how many percent of terminals that transmit data that cannot be demodulated occur with respect to the total number of terminals.
Here, for example, when the number of terminals that transmit data that cannot be demodulated exceeding the noise rise frame in the autonomous mode exceeds a predetermined ratio with respect to the total number of terminals, the number of terminals in the autonomous mode is too large. A case where the ratio is less than or equal to the ratio is defined as a state where the number of terminals in the autonomous mode is too small, and a case other than these is defined as a state where the number of terminals in the autonomous mode is appropriate.

In step ST6c, the radio resource management unit 66 checks how much the noise rise frame of the autonomous mode in the current base station is with respect to the above average value, and whether the number of terminals in the autonomous mode is appropriate based on the result. Determine whether or not.
Here, if the radio resource management unit 66 determines that the number of terminals in the autonomous mode is too large, the QoS parameter mapping unit 64 in the base station control device 3 allows a delay in the terminals 2 in the autonomous mode. Is searched (step ST7c).
A state in which the number of terminals in autonomous mode in a cell is large means that the number of terminals in a cell that exceeds the number of terminals that can be given an allowable margin within the range that can be demodulated for noise rise in autonomous mode is exceeded. It is specified that the number of terminals in the mode is large.

  Further, the QoS parameter mapping unit 64 determines whether or not the terminal 2 is handling data that allows a delay based on the QoS class for the terminal 2 operating in the autonomous mode. For example, it is determined whether the delay is allowed or not for the four classes of QoS described above. Further, in the conversational class and streaming class in the W-CDMA system, the delay amount (Transfer delay) is specified in ms units, and therefore, an allowable delay may be determined based on this.

Subsequently, the radio resource management unit 66 maintains the current switching threshold value for the terminal 2 determined to be non-delayable by the QoS parameter mapping unit 64 in step ST7c, or allows the delay allowance. A threshold is set in which the amount of decrease is smaller than in the case (step ST10c).
Here, of the terminals 2 belonging to the QoS class that does not allow delay, the radio resource management unit 66 increases the switching threshold as the delay amount in the QoS parameter is large (the delay allowance is loose). For example, a coefficient k corresponding to the degree of congestion in the cell of the terminal 2 in the autonomous mode is provided for the reduction width of the switching threshold.

When there is a terminal 2 in which the QoS parameters of 20 ms and 80 ms of delay are set, if the coefficient k = 1, the switching threshold is lowered as follows.
The reduction amount of the terminal 2 with the delay amount of 20 ms is k · 20 / (20 + 80) = 1/5 = 20%.
The reduction rate of the terminal 2 with the delay amount of 80 ms is k · 80 / (20 + 80) = 4/5 = 80%.

  It should be noted that, by reducing the switching threshold value of some autonomous mode terminals 2, if the portion of the allowable margin for scheduling mode of the base station that has been pressed to secure the allowable margin for autonomous mode is eliminated The radio resource manager 66 maintains the current threshold value by setting the coefficient k to 0.

Further, the radio resource management unit 66 sets the switching threshold value to be lowered by a larger reduction range than that in the case of step ST10c for the terminal 2 determined to be allowed delay by the QoS parameter mapping unit 64 in step ST7c. (Step ST11c). In this way, the radio resource management unit 66 sets the switching threshold so as to shift from the excessive autonomous mode to the scheduling mode.
When determining that the number of terminals in the autonomous mode is appropriate in step ST6c, the radio resource management unit 66 maintains the current switching threshold value (step ST8c).

Further, if it is determined in step ST6c that the number of terminals in the autonomous mode is too small, the radio resource management unit 66 increases the value of the switching threshold currently set in the terminal 2 (step ST9c).
Here, the state in which the number of terminals in the autonomous mode is too small means that even if data transmission is executed at a data rate corresponding to the transmission data amount, a margin more than necessary is generated for the noise rise margin allocated to each terminal 2. It is a state that ends up.
In this case, if the threshold value is increased to increase the number of terminals in the autonomous mode in the cell, the noise rise margin assigned to each terminal 2 can be used effectively.
As described above, the radio resource management unit 66 determines the change width of the switching threshold based on the transmission data rate, the number of terminals in the autonomous mode, the noise rise frame in the scheduling mode, and the delay amount to be allowed.

  When the switching threshold value is determined in any of step ST8c to step ST11c, the radio resource management unit 66 proceeds to the process of step ST10b in FIG. 19 and generates a layer 3 message including the changed threshold value. To the base station.

The base station that has received the threshold change message from the base station control device 3 determines that the individual channel (DPCH) communication has been established with the threshold setting target terminal 2 in step ST11b of FIG. If communication on the dedicated channel is not established using the DPCH), the above information is transmitted to the target terminal 2 using the common channel (FACH).
Thereafter, in the processing from step ST12b to step ST14b in FIG. 19, the mobile communication terminal 2 changes the value of the switching threshold in its own transmission data buffer.

  In step ST9c, the QoS parameter mapping unit 64 determines whether or not to allow delay based on the QoS parameter, and based on the determination result, the radio resource management unit 66 determines the terminal 2 that does not particularly allow delay. It is also possible to configure so that the switching threshold is increased more than the delay tolerance. In this way, it is possible to switch to the transmission mode most appropriate for each terminal.

  Moreover, if the range of the threshold value increase / decrease performed at one time is too large in step ST9c, step ST10c, and step ST11c, there is a possibility that more terminals 2 switch the transmission mode than necessary. Therefore, it is desirable that the threshold value increase / decrease performed at a time be suppressed to a constant value in consideration of the number of terminals in the autonomous mode in the cell and the threshold value is gradually changed.

As described above, in the second method, since the switching threshold is individually set for the terminal 2 in the cell, the communication mode can be set according to the communication condition required for each terminal 2. In particular, the QoS set for data communication with the individual terminals 2 by switching between the autonomous mode and the scheduling mode depending on whether or not the data handled by the individual terminals 2 allows delay. Can be guaranteed.
In addition, although the radio | wireless resource management part 66 in the base station control apparatus 3 demonstrated the structure which determines a communication mode switching threshold in the 1st method and the 2nd method, this invention is limited to this. is not.
For example, the base station may obtain QoS information from the base station control device 3, and the uplink packet communication management unit 24 in the base station may determine the communication mode switching threshold.

Further, the threshold value determined on the base station control device 3 side may be changed and notified to the terminal 2 on the base station side according to the current traffic situation. That is, the present invention includes a configuration in which the base station and the base station control device 3 jointly determine the threshold value.
In this case, the uplink packet communication management unit 24 can be considered as a configuration on the base station side that changes the threshold value notified from the base station control device 3.

Next, the third method will be described.
In this method, transmission mode switching threshold change information is transmitted to individual terminals using physical layer signaling (L1 signaling), so that the most suitable transmission mode for each terminal can be switched. In addition, since the third method uses physical layer signaling that is faster than the second method, it is possible to change the switching threshold that follows packet traffic fluctuations.

Physical layer signaling (hereinafter referred to as “L1 signaling”) is information for assigning information related to the threshold to bit information of the physical layer for setting the communication conditions of the physical layer between the mobile communication terminal 2 and the base station. .
For example, a new channel and its slot format are introduced to perform physical layer signaling. Here, the slot format defines how to allocate bits per slot of transmission packet data.
That is, in the change of the switching threshold by physical layer signaling, the setting bits of the change information of the switching threshold in the transmission packet data are defined in the slot format.

As a specific example, UL-SICCH or the like is defined as a new channel for physical layer signaling, and a bit for setting a binary command specifying switching and raising / lowering of the threshold value is defined in the slot format.
In addition, there is a method by puncturing. In this method, a part of data set in the currently used dedicated channel (DPCH) is deleted, and information for specifying a switching threshold value is inserted into the part. This can be realized when the original data has a powerful error correction function and a certain amount of error from the original data can be corrected.
In this method, since the bit error rate for the original data increases, the number of bits for setting the switching threshold value cannot be increased too much.

  FIG. 21 is a diagram illustrating an example of distribution of the noise rise margin of the base station when the base station according to Embodiment 1 determines the transmission mode switching threshold of the terminal according to the third method. A basic concept in the third method will be described with reference to FIG.

It is assumed that a plurality of mobile communication terminals 2 are accommodated in a cell as a state before changing the transmission mode switching threshold. Further, as shown in FIG. 21A, the noise rise margin in the base station includes an allowable margin for noise rise caused by the autonomous mode and the scheduling mode, and noise rise caused by transmission on a dedicated channel or the like. It is assumed that an allowable margin (individual channel or other area in the figure) is distributed.
Here, the noise rise margin in the base station is an allowable margin in which a margin for interference that should be considered from the operating state of other cells and QoS is added to the above-described jamming margin.
In general, intermittent transmission tends to occur in packet communication. In other words, when uploading a large amount of data, the communication load increases, but when the transmission stops, the load often decreases.

When the number of terminals in the cell is large and each terminal 2 handles a completely different communication service, the temporal fluctuation of traffic is absorbed to some extent from a statistical viewpoint. However, when many terminals 2 in the cell handle the same communication service, the temporal fluctuation of traffic may be overloaded or quiet.
For example, when the frequency of packet communication of the terminal 2 in the scheduling mode increases (becomes active), as shown in FIG. 21 (b), a larger margin for the scheduling mode is distributed among the allowable margins of the base station. Therefore, the margin for autonomous mode is reduced accordingly.

  Conversely, when the frequency of packet communication of terminals in the scheduling mode decreases (becomes inactive), as shown in FIG. 21 (c), the margin for the scheduling mode is reduced from the allowable margin of the base station. Therefore, it is desirable that the autonomous mode margin be controlled accordingly.

As described above, when reducing the autonomous mode margin, it is sufficient to switch some terminals 2 from the autonomous mode to the scheduling mode. Conversely, when increasing the autonomous mode margin, some terminals are switched from the scheduling mode to the autonomous mode. Switch.
Here, to switch the transmission mode as described above following the traffic of each transmission mode that fluctuates at high speed, it is necessary to change the switching threshold as quickly as possible. Therefore, in the third method, physical layer signaling faster than the layer 3 message is used.

  FIG. 22 is a diagram showing a change sequence in the case where the transmission data buffer threshold is changed by the third method in the mobile communication system according to the first embodiment. The uplink packet transmission management unit 24 in the base station is designated in advance by the base station control device 3 as a noise rise frame for uplink enhancement (step ST1d).

More specifically, the radio resource management unit 66 in the base station control device 3 performs QoS parameters managed by the QoS parameter mapping unit 64, operating states of cells other than the target base station, and traffic of cells of the target base station. In consideration of the situation, an allowable margin within a certain range for the target base station is obtained and notified to the target base station.
The permissible margin notified to the base station is the non-controllable in FIG. 5 comprising the scheduling mode margin and the autonomous mode margin, which are controllable margins in FIG. The assigned margin is distributed.

Here, the base station control device 3 determines the entire allowable margin within a certain range and sets it in the base station. On the other hand, the distribution ratio of the permissible margin for each transmission mode in the permissible margin is determined by the uplink packet transmission management unit 24 in the base station.
Next, the uplink packet transmission management unit 24 in the base station accepts a request for a transmission data rate in data transmission in the scheduling mode from the terminal 2 in the own cell (step ST2d).

The uplink packet transmission management unit 24 functions as a scheduler that manages data transmission in the scheduling mode in addition to determining an allowable data rate in the autonomous mode. The transmission data rate from the terminal 2 described above is registered in the uplink packet transmission management unit 24 as the contents of the data transmission schedule in the scheduling mode.
Thereafter, the uplink packet transmission management unit 24 determines whether or not the load situation in the traffic in the scheduling mode is appropriate with respect to the allowable margin allocated from the base station controller 3, and each transmission mode is determined according to the determination result. Is switched so as to be switched (step ST3d). This process will be described later in detail with reference to FIG.

  When the switching threshold value is determined in step ST3d, the uplink packet transmission management unit 24 sets the threshold value after the change in the L1 signaling in accordance with the transmission operation described above with reference to FIG. An instruction is given (step ST4d).

Note that, as described above, when the switching threshold change instruction in L1 signaling is a binary command that specifies only to raise or lower the threshold value, there is a possibility that the change instruction may not be accurately transmitted to the terminal 2 due to a transmission error or the like. There is.
For this reason, the base station continuously sends an L1 layer command a plurality of times so that the terminal 2 can reliably receive the switching threshold change instruction (step ST5d).

  As described above, in the third method, the process involving the base station controller 3 is minimized in the switching threshold change process. For this reason, the communication between the base station and the base station control device 3 can be omitted, and the switching threshold of the terminal 2 can be changed quickly.

The operation in step ST3d in FIG. 22 of the mobile communication system according to the first embodiment will be described in detail using the flowchart shown in FIG.
First, the uplink packet transmission management unit 24 in the base station checks the situation where data transmission in the scheduling mode is scheduled in the own cell (step ST1e).
Next, the uplink packet transmission management unit 24 determines whether or not the traffic load in the scheduling mode is appropriate for the allowable margin allocated from the base station control device 3 based on the scheduling situation checked in step ST1e. (Step ST2e).

Specifically, the uplink packet transmission management unit 24 determines whether the traffic load in the scheduling mode is appropriate based on the number of terminals that have notified the data transmission in the scheduling mode and the amount of data to be transmitted in the data communication. Determine.
The uplink packet transmission management unit 24 has, for example, a large number of terminals in the scheduling mode in the own cell and a large amount of data to be transmitted in the data communication, and communication conditions (delays) specified by the QoS for data transmission in the scheduling mode. If the request is not satisfied, it is determined that the traffic in the scheduling mode is too heavy.

On the contrary, the number of terminals in the scheduling mode in the own cell and the amount of data to be transmitted in the data communication are small, and the communication conditions (delay request, etc.) specified by the QoS for data transmission in the scheduling mode are sufficiently If it is satisfied but most of the allowable margin for the scheduling mode is not utilized, it is determined that the traffic load in the scheduling mode is too low.
In the scheduling mode, only the radio resources allocated to the uplink packet transmission management unit 24 are used. If the allocation is repeated, the terminal 2 in the scheduling mode can be set without limitation.

However, when a large number of terminals 2 are set in the scheduling mode, data transmission is executed only in the order according to the schedule, so that a delay is inevitably caused.
Therefore, the determination method determines whether or not the traffic load in the scheduling mode is appropriate depending on how much delay is allowed for the data handled by the terminal 2 in the scheduling mode.

Further, as a determination method other than the above, there is a process that focuses on the autonomous mode. Specifically, the uplink packet transmission management unit 24 performs noise rise assuming that the terminal 2 in the autonomous mode in its own cell transmits data at the maximum value of the allowable data rate range notified in advance. Approximate.
When the allowable margin for the autonomous mode corresponding to the noise rise is set, the state where the allowable margin for the scheduling mode must be reduced at this time is determined as a state where the traffic load in the scheduling mode is excessive.

On the contrary, even if the allowable margin for the autonomous mode corresponding to the noise rise is set, the state where the allowable margin for the scheduling mode may be increased at this time is determined as a state where the traffic load in the scheduling mode is too small. .
It should be noted that in both the determination methods, it is determined that the traffic load is in an appropriate state except when the traffic load in the scheduling mode is high or low.

If it is determined in step ST2e that the traffic load is in an appropriate state, the uplink packet transmission management unit 24 ends the process shown in FIG. 23 and does not notify the terminal 2.
If it is determined in step ST2e that the traffic load is high, the uplink packet transmission management unit 24 searches for a terminal 2 having a high transmission frequency in the autonomous mode within the own cell (step ST3e). For example, it is determined that the terminal 2 in which the number of prior notifications of the allowable data rate in the autonomous mode exceeds a predetermined value is high in transmission frequency in the autonomous mode.

  Next, the uplink packet transmission management unit 24 determines whether or not the terminal 2 that has determined that the transmission frequency in the autonomous mode is high in Step ST3e allows delay (Step ST4e). This determination is performed based on the delay amount specified by the QoS of the data handled by the terminal 2. At this time, if it is determined that the terminal 2 does not allow delay, the uplink packet transmission management unit 24 ends the process illustrated in FIG. 23 and does not notify the terminal 2.

  On the other hand, when determining that the terminal 2 allows delay, the uplink packet transmission management unit 24 lowers the switching threshold value for the terminal 2 and proceeds to the process of step ST4d in FIG. 22 (step ST5e).

In this way, when the changed switching threshold value is notified by L1 signaling, the terminal 2 switches the transmission mode according to the threshold value and responds to that effect to the base station.
The uplink packet transmission management unit 24 in the base station determines whether or not the terminal 2 has switched to the scheduling mode based on the transmission mode switching response from the terminal 2 (step ST6e).
At this time, if it is determined that the mode has been switched to the scheduling mode, the uplink packet transmission management unit 24 estimates the noise rise for the new scheduling mode, and within the allowable margin set by the base station control device 3, the noise rise of the scheduling mode. The margin (noise rise frame) is increased (step ST7e).

  On the other hand, when it is determined in step ST6e that there is no response indicating that the transmission mode has been switched from the terminal 2 and it has not been shifted to the scheduling mode, the uplink packet transmission management unit 24 proceeds to the process of step ST5d in FIG. The L1 signaling command in which the changed switching threshold value is set is continuously transmitted to the target terminal 2 (step ST8e). Thereafter, if there is a response indicating that the transmission mode has been switched from the terminal 2, the process returns to step ST6e.

In addition, when the uplink packet transmission management unit 24 determines in step ST2e that the traffic load in the scheduling mode is small, among the terminals 2 accommodated in the own cell, the terminal 2 having a low transmission frequency in the scheduling mode, or The terminal 2 that handles data that cannot tolerate delay is searched (step ST9e).
In step ST9e, when the terminal 2 with a low transmission frequency in the scheduling mode or the terminal 2 that handles data that cannot tolerate delay is extracted, the uplink packet transmission management unit 24 increases the switching threshold value for the terminal 2. Then, the process proceeds to step ST4d in FIG. 22 (step ST10e).

As described above, when the changed switching threshold value is notified by the L1 signaling, the terminal 2 switches the transmission mode according to the threshold value and responds to that effect to the base station.
The uplink packet transmission management unit 24 determines whether or not the terminal 2 has been switched to the autonomous mode based on the transmission mode switching response from the terminal 2 (step ST11e).
At this time, if it is determined that the mode has been switched to the autonomous mode, the uplink packet transmission management unit 24 approximates the noise rise for the new autonomous mode, and the noise rise of the autonomous mode is within the allowable margin set by the base station control device 3. The margin (noise rise frame) is increased (step ST12e).

  On the other hand, if it is determined in step ST11e that there is no response indicating that the transmission mode has been switched from the terminal 2 and it has not shifted to the autonomous mode, the uplink packet transmission management unit 24 proceeds to the processing of step ST5d in FIG. The L1 signaling command in which the changed switching threshold value is set is continuously transmitted to the target terminal 2 (step ST13e). Thereafter, if there is a response indicating that the transmission mode has been switched from the terminal 2, the process returns to the process from step ST11e.

As described above, according to the third method, the change information of the switching threshold is notified to the terminal 2 by physical layer signaling faster than in the case of the layer 3 message, so in the packet communication between the base station and the terminal 2 It is possible to change the switching threshold following the traffic fluctuation. Further, according to the third method, an allowable margin for noise rise in each transmission mode can be appropriately distributed according to traffic fluctuation.
In the third method described above, the configuration in which the uplink packet transmission management unit 24 in the base station determines the communication mode switching threshold has been described, but the present invention is not limited to this.

For example, the radio resource management unit 66 in the base station control device 3 may be configured to determine the communication mode switching threshold based on the QoS information that it grasps and the current traffic situation obtained from the base station.
In this case, information specifying the communication mode switching threshold value is notified from the base station control device 3 to the base station, and is notified from the base station to the terminal 2 by the third method.

In the above embodiment, the configuration on the base station side including the base station control device 3 determines the switching threshold value of the terminal 2, and the terminal 2 transmits the transmission mode according to the threshold value specified from the base station side. Explained the process of switching. However, the present invention is not limited to the above configuration.
For example, the configuration on the base station side including the base station control device 3 determines the transmission mode to be switched based on the switching threshold value of the terminal 2, and the terminal 2 switches the transmission mode according to the instruction from the base station side. May be.

Hereinafter, an embodiment in which each of the first to third methods is applied to this configuration will be described.
First, using the flowchart shown in FIG. 24, the operation in the case where the first method is applied to the configuration in which the base station side determines the transmission mode to be switched and the terminal 2 switches the transmission mode in accordance with the instruction from the base station side. Will be described in detail.

Since the process from step ST1a to step ST8a is the same as that of FIG. 16, description is abbreviate | omitted. In any step from step ST6a to step ST8a, when the radio resource management unit 66 in the base station control device 3 determines the switching threshold value, it notifies the base station of this threshold value.
The uplink packet transmission management unit 24 in the base station compares the threshold value notified from the base station control device 3 with the transmission data amount notified in advance from each terminal 2 in the own cell, and The transmission mode to be set to 2 is determined (step ST9a).

For example, when the amount of transmission data notified in advance exceeds the threshold value, it is determined that the scheduling mode should be set, and in the opposite case, the autonomous mode is selected.
When the transmission mode is determined in step ST9a, the uplink packet transmission management unit 24 instructs the broadcast information transmission unit 28 to perform signaling for switching to the transmission mode for each terminal 2 using the broadcast information. (Step ST10a).
Specifically, in the processing of step ST11 in FIG. 15, information specifying the transmission mode determined on the base station side is transmitted instead of the information including the changed switching threshold value.

In this way, the base station side can know which transmission mode the terminal 2 has switched to by determining not only the switching threshold value but also the transmission mode to be switched.
For this reason, it is possible to omit the response signaling for notifying the base station of the transmission mode switched by the terminal 2, which is necessary when the terminal 2 switches the transmission mode according to the threshold value designated from the base station side. it can.

  Next, using the flowchart shown in FIG. 25, when the base station side determines the transmission mode to be switched and the terminal 2 applies the second method to the configuration in which the transmission mode is switched according to the instruction from the base station side. The operation will be described in detail.

Since the process from step ST1c to step ST11c is the same as that of FIG. 20, description is abbreviate | omitted. When the radio resource management unit 66 in the base station controller 3 determines the switching threshold value in any of the steps ST8c, ST9c, ST10c, and ST11c, it notifies the base station of this threshold value.
The uplink packet transmission management unit 24 in the base station compares the threshold value notified from the base station control device 3 with the transmission data amount notified in advance from the terminal 2 that is the transmission mode switching target, A transmission mode to be set in the terminal 2 is determined (step ST12c).
When the transmission mode is determined in step ST12c, the uplink packet transmission management unit 24 instructs the downlink dedicated channel transmission unit 29 or the downlink common channel transmission unit 34 to use the dedicated channel or the common channel for the target terminal 2. Then, signaling for switching to the transmission mode is executed (step ST13a).

  Specifically, in the process of step ST11b in FIG. 19, not the information including the changed switching threshold value but the information specifying the transmission mode determined on the base station side is transmitted. In this case, the processes of step ST13b and step ST14b in FIG. 19 are omitted.

In this way, the base station side can know which transmission mode the terminal 2 has switched to by determining not only the switching threshold value but also the transmission mode to be switched.
For this reason, it is possible to omit the response signaling for notifying the base station of the transmission mode switched by the terminal 2, which is necessary when the terminal 2 switches the transmission mode according to the threshold value designated from the base station side. it can.

In the above description, the configuration in which the radio resource management unit 66 in the base station control device 3 determines the communication mode switching threshold has been described, but the present invention is not limited to this.
For example, the base station may obtain QoS information from the base station control device 3, and the uplink packet communication management unit 24 in the base station may determine the communication mode switching threshold.
By doing in this way, in the communication mode switching threshold determination process, it is possible to reduce the process intervening by the base station controller 3, and to suppress an increase in the number of signaling between the base station and the base station controller 3. be able to.

In addition, the base station changes the threshold value determined on the base station control device 3 side according to the current traffic situation and the like, and transmits the changed threshold value and the terminal 2 notified in advance. The transmission mode may be determined by comparing the data amount.
That is, the present invention includes a configuration in which the base station and the base station control device 3 jointly determine the threshold value. In this case, the uplink packet communication management unit 24 can be considered as a configuration on the base station side that changes the threshold value notified from the base station control device 3.

  Next, in the case where the third method is applied to the configuration in which the base station side determines the transmission mode to be switched using the flowchart shown in FIG. 26 and the terminal 2 switches the transmission mode according to the instruction from the base station side. The operation will be described in detail.

First, since the process from step ST1e to step ST4e is the same as that of FIG. 23, description is abbreviate | omitted. If it is determined in step ST4e that the terminal 2 allows delay, the uplink packet transmission management unit 24 lowers the switching threshold value for the terminal 2 (step ST5e-1).
Next, the uplink packet transmission management unit 24 compares the threshold value determined in step ST5e-1 with the transmission data amount notified in advance from the terminal 2 searched in step ST4e, and determines the terminal 2 Is determined (step ST5e-2).

Subsequently, the uplink packet transmission management unit 24 shifts the information specifying the transmission mode to be set to the terminal 2 to the process of step ST4d in FIG. 22 as the above-described L1 signaling (step ST5e-3).
The subsequent processing from step ST6e to step ST8e is the same as that in FIG.
Also, in step ST9e, when a terminal 2 with a low transmission frequency in the scheduling mode or a terminal 2 handling data that cannot tolerate delay is extracted, the uplink packet transmission management unit 24 increases the switching threshold value for the terminal 2. (Step ST10e-1).

Next, the uplink packet transmission management unit 24 compares the threshold value determined in step ST10e-1 with the transmission data amount notified in advance from the terminal 2 searched in step ST9e, and The transmission mode to be set is determined (step ST10e-2).
Subsequently, the uplink packet transmission management unit 24 shifts the information specifying the transmission mode to be set to the terminal 2 to the process of step ST4d in FIG. 22 as the above-described L1 signaling (step ST10e-3).
Since the process from step ST11e to step ST13e of migration is the same as that in FIG.

In the third method described above, the configuration in which the uplink packet transmission management unit 24 in the base station determines the communication mode switching threshold has been described, but the present invention is not limited to this.
For example, the radio resource management unit 66 in the base station control device 3 may be configured to determine the communication mode switching threshold based on the QoS information that it grasps and the current traffic situation obtained from the base station.
In this case, information specifying the communication mode switching threshold value is notified from the base station control device 3 to the base station, and is notified from the base station to the terminal 2 by the third method.

Further, in the above description, the configuration has been described in which the uplink packet transmission management unit 24 in the base station determines the communication mode, but the present invention is not limited to this.
For example, the radio resource management unit 66 in the base station control device 3 acquires the QoS information that the mobile station grasps itself, the transmission data amount of data communication that the terminal 2 intends to execute via the base station, and the like. The transmission mode to be set to 2 may be determined.
In this case, in the processing of steps ST10 and ST11 in FIG. 15 and steps ST10b and ST11b in FIG. 19, information specifying the transmission mode determined on the base station side is transmitted instead of the information including the changed switching threshold value. Will be.
In addition, the transmission mode determined by the radio resource management unit 66 is notified from the base station control device 3 to the base station, and then the base station notifies the terminal 2 by the above methods.

As described above, according to the first embodiment, it is possible to set an appropriate transmission mode for the terminal 2 in accordance with the operation status of the base station, and to set an allowable margin for noise rise set in the base station. An allowable margin for the transmission mode can be appropriately distributed.
Also, when setting the switching threshold for each terminal 2, it is possible to sort each transmission mode in consideration of the QoS of the data handled by that terminal 2, and efficiently reflecting the data transmission needs of each terminal 2 Wireless resources can be used.

In the above embodiment, it has been described that the base station side acquires the transmission buffer information for determining the transmission mode switching of the terminal 2 by signaling from the terminal 2 to the base station.
Here, the signaling of transmission buffer information from the terminal 2 to the base station may not satisfy the delay request even if the transmission mode is switched unless the frequency is changed according to the delay tolerance of the data handled by the terminal 2. is there.
For example, if the signaling frequency of the transmission buffer information from the terminal 2 arriving at the base station is low, the base station side delays grasping the current state of the transmission data buffer of the terminal 2.
In this case, the process of switching the terminal 2 to the scheduling mode or the autonomous mode is delayed, and there is a possibility that the delay request in the data communication of the terminal 2 cannot be satisfied.

Therefore, the mobile communication terminal 2 may change the signaling frequency of the transmission buffer information for the base station according to the delay request set for the data communication handled by itself.
For example, when the above-mentioned signaling is executed from the terminal 2 to the base station at a predetermined cycle, for the terminal 2 that performs data communication with a severe delay request, the above-mentioned signaling is executed at a short cycle and the data communication with a low delay request is performed. The terminal 2 that handles the signaling performs a long cycle. This signaling cycle is set individually for each terminal according to the allowable delay amount of data communication to be executed.

The signaling cycle generation process will be described. Counter information called SFN (System Frame Number), which is the basis of transmission timing, is set in P-CCPCH (BCH). The uplink packet transmission management unit 24 in the base station determines the signaling cycle of transmission buffer information by the terminal 2 based on the QoS parameters obtained from the base station control device 3.
As a method of setting this signaling cycle in the terminal 2, as in the switching threshold signaling described above, use of broadcast information in the first method (collective designation to the group of the terminals 2), individual or in the second method Use of a common channel (individual designation to the terminal 2) and physical layer signaling in the third method are conceivable.
When the mobile communication terminal 2 receives the information on the signaling period from the base station, the mobile communication terminal 2 demodulates the signal set for each data channel from the despreading demodulation unit 46 as described with reference to FIG. The protocol processing unit 56 acquires information on the signaling period from the signal demodulated by the despreading demodulation unit 46.

Next, the protocol processing unit 56 sets the cycle obtained from the information related to the signaling cycle in the buffer status transmitting unit 55 as a UL-SICCH transmission cycle for notifying the base station of the status of the transmission data buffer 58. . Further, the mobile communication terminal 2 synchronizes with the base station at the timing at which data should be transmitted by the SFN value set in the P-CCPCH (BCH).
Grouping may be used as a method for efficiently specifying the signaling period. More specifically, for example, the terminals 2 belonging to the conversational class or the streaming class using the QoS class are grouped according to the maximum delay amount allowable in the QoS class, and the signaling period is determined.

  On the other hand, for terminals 2 belonging to QoS classes other than those described above, for example, a longer period than terminals 2 belonging to the conversational class or streaming class is set. This method has an advantage that the amount of interference can be managed in the communication mode corresponding to the QoS class for the terminals 2 of each group.

  Next, an application example will be described in which the signaling of the transmission buffer information is performed when the state of the mobile communication terminal 2 reaches a predetermined condition without periodically performing signaling as described above.

The predetermined condition is that the terminal 2 performs signaling of the transmission buffer information to the base station when a certain amount of transmission data is accumulated in the transmission data buffer 58 for uplink packet communication of the terminal 2. Can be considered.
In this case, the signaling of the transmission buffer information is not executed until a certain amount of transmission data is accumulated in the transmission data buffer 58. However, depending on the data handled by the terminal 2, the signaling may be executed without waiting for a certain amount of transmission data to be accumulated in the transmission data buffer 58.
For example, a response signal from an application executed by the terminal 2 via the Internet or the like has a small data amount, but its presence should be notified to the base station as soon as possible.

Therefore, a timer that designates the signaling cycle is set for the terminal 2, and when handling data with severe delay requests, the timer is constant without waiting for a certain amount of transmission data to be accumulated in the transmission data buffer. You may comprise so that the said signaling may be performed when time passes.
The designation of the timer is considered to be explicitly signaled from the configuration on the base station side or set by the terminal 2 itself.

First, using FIG. 10 and FIG. 11, the operation when the timer is specified by explicitly signaling from the configuration on the base station side will be described. Here, it is assumed that the uplink packet transmission management unit 51 in the terminal 2 functions as the timer.
The base station control device 3 generates timer information that specifies a period according to the QoS parameter, using the QoS parameter related to data communication by the terminal 2 to be set as a timer.

Next, the base station acquires the timer information from the base station control device 3 and transmits it to the terminal 2 as information on the dedicated channel via the downlink dedicated channel transmitter 29.
In the terminal 2, the downlink dedicated channel receiving unit 63 receives the information on the dedicated channel and transmits it to the protocol processing unit 56. The protocol processing unit 56 reads timer information from the information on the dedicated channel and sends it to the uplink packet transmission management unit 51.
The uplink packet transmission management unit 51 sets a timer according to the timer information, and instructs the buffer state transmission unit 55 to execute signaling of the transmission buffer information when a timeout occurs.

Next, a process for autonomously managing the timer on the terminal 2 side will be described.
First, the uplink packet transmission management unit 51 determines a timer value based on the QoS information that the self packet grasps and the presence / absence of past transmission. When this timer times out, the uplink packet transmission management unit 51 instructs the buffer status transmission unit 55 to execute signaling of the transmission buffer information.
As a timer designation method for efficiently executing the signaling, for example, the base station control device 3 or the uplink packet transmission management unit 51 may set a timer in proportion to the allowable delay amount in the conversational class or the streaming class. Conceivable.

In the interactive class and the background class, the base station control device 3 and the uplink packet transmission management unit 51 set the timer time for the terminal 2 with a history of communication in the past from the terminal 2 with which communication was performed for the first time. Is specified shorter, and the specified time of the timer is gradually lengthened as the communication interval further increases.
By doing in this way, the signaling frequency of the transmission data buffer information with respect to a base station can be flexibly set according to the data communication needs. For example, the number of signaling can be efficiently controlled for the terminal 2 performing data communication with low traffic by, for example, leaving the signaling interval.

  Further, the method of periodically signaling described above and the method of using a timer may be used in combination. For example, the terminal 2 that performs data communication in which the delay amount is set strictly, periodically performs transmission data buffer information signaling to the base station, and performs data communication in which the delay amount is set loosely. Performs the above signaling at intervals specified by the timer.

  More specifically, in the terminal 2 that handles data communication belonging to the conversational class or the streaming class, the signaling cycle is set in accordance with the maximum delay amount allowable in the QoS class. In addition, the terminal 2 that handles data communication belonging to the interactive class or the background class executes signaling according to the QoS information that it knows and the timer set based on the presence of past transmission.

  By doing so, it is possible to suppress an increase in signaling of transmission data buffer information from the terminal 2 more than necessary while managing the amount of interference of data communication by the terminal 2 on the base station side. As a result, the entire mobile communication system can perform signaling efficiently.

  As described above, the communication mode control method according to the present invention can be used for mobile communication terminals such as mobile phones that support uplink packet communication, base stations, and base station control devices.

1 is a diagram schematically showing a configuration of a mobile communication system according to Embodiment 1 of the present invention. It is a figure which shows the structure of the channel in the mobile communication system by Embodiment 1 of this invention. It is a figure explaining the communication mode in the wireless multiplex data mode communication between the terminal and base station in the mobile communication system by Embodiment 1 of this invention. It is a figure explaining the communication mode in the wireless multiplex data mode communication between the terminal and base station in the mobile communication system by Embodiment 1 of this invention. It is a figure explaining the threshold of the transmission data buffer used as the reference | standard which switches the communication mode of the mobile communication terminal by Embodiment 1 of this invention. It is a figure which shows the tolerance margin with respect to the interference amount resulting from each factor in the uplink signal to the base station by Embodiment 1 of this invention. It is a figure which shows the example of distribution of the noise rise margin with respect to the autonomous mode and scheduling mode in case the some terminal is using the uplink packet communication within a cell. It is a figure which shows the case where the threshold of communication mode switching determination of a transmission data buffer is set low in the case shown in FIG. It is a figure which shows the example of distribution of the noise rise margin with respect to the autonomous mode and scheduling mode when there are few terminals using uplink packet communication in a cell. FIG. 9 is a diagram illustrating a case where a threshold for determining a communication mode switching of a transmission data buffer is set high in the case illustrated in FIG. 8. It is a block diagram which shows the internal structure of the base station of FIG. It is a block diagram which shows the internal structure of the mobile communication terminal of FIG. It is a block diagram which shows the internal structure of the base station control apparatus of FIG. It is a figure which shows the example of distribution of the noise rise margin of a base station when the base station control apparatus by Embodiment 1 of this invention determines the transmission mode switching threshold of a terminal according to the 1st method. It is a figure explaining the change of the transmission mode switching threshold according to distribution of the noise rise margin shown in FIG. It is a figure which shows the change sequence in the case of performing the threshold change of the transmission data buffer by the 1st method in the mobile communication system by Embodiment 1 of this invention. 16 is a flowchart for explaining in detail an operation in step ST9 shown in FIG. It is a figure which shows the example of distribution of the noise rise margin of a base station when the base station control apparatus by Embodiment 1 determines the transmission mode switching threshold of a terminal according to the 2nd method. It is a figure explaining the change of the transmission mode switching threshold according to distribution of the noise rise margin shown in FIG. It is a figure which shows the change sequence in the case of performing the threshold change of the transmission data buffer by the 2nd method in the mobile communication system by Embodiment 1 of this invention. 20 is a flowchart for explaining in detail an operation in step ST9b shown in FIG. It is a figure which shows the example of distribution of the noise rise margin of a base station when the base station by Embodiment 1 determines the transmission mode switching threshold of a terminal according to the 3rd method. It is a figure which shows the change sequence in the case of performing the threshold change of the transmission data buffer by the 3rd method in the mobile communication system by Embodiment 1 of this invention. It is a flowchart explaining the operation | movement in step ST3d shown in FIG. 22 in detail. It is a flowchart which shows operation | movement in case a 1st method is applied with respect to the structure which a mobile communication terminal switches a transmission mode according to the instruction | indication from the base station side. It is a flowchart which shows operation | movement in case a 2nd method is applied with respect to the structure which a mobile communication terminal switches a transmission mode according to the instruction | indication from the base station side. It is a flowchart which shows operation | movement in case a 3rd method is applied with respect to the structure which a mobile communication terminal switches a transmission mode according to the instruction | indication from the base station side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mobile communication system, 2 Mobile communication terminal, 3 Base station control apparatus, 4a, 4b Base station, 5 Modulation part, 6 Down channelization code generator, 7 Down scrambling code generator, 8 Frequency conversion part, 9 Power Amplification unit, 10 antenna, 11 low noise amplification unit, 12 frequency conversion unit, 13 uplink scrambling code generator, 14 uplink channelization code generator, 15 despreader, 16 desired wave power measurement unit, 17 interference wave power measurement Unit, 18 channel quality measurement unit, 19 quality target comparison unit, 20 TPC generation unit, 21 TFRI reception unit, 22 decoding unit, 23 response signal generation unit, 24 uplink packet transmission management unit, 25 transmission rate / timing designation information transmission , 26 Timing management unit, 27 Pilot signal generation unit, 28 Broadcast information transmission unit, 29 Downlink individual channel Channel transmitter, 30 demodulator, 31 transmission buffer amount receiver, 32 uplink individual channel receiver, 33 uplink common channel receiver, 34 downlink common channel transmitter, 35 modulator, 36 uplink channelization code generator, 37 uplink Scrambling code generator, 38 frequency conversion unit, 39 power amplification unit, 40 antenna, 41 low noise amplifier, 42 frequency conversion unit, 43 power control unit, 44 downlink channelization code generator, 45 downlink scrambling code generator, 46 Despreading demodulation unit, 47 Common pilot signal receiving unit, 48 Timing management unit, 49 Transmission permission information receiving unit, 50 Threshold change unit, 51 Up packet transmission management unit (communication management unit), 52 EUDTCH transmission processing unit, 53 TFRI Transmission processing unit, 54 Transmission mode switching unit, 55 bar Buffer state transmitter, 56 protocol processor, 57 response signal receiver, 58 transmission data buffer for uplink packet communication, 59 uplink common channel transmitter, 60 uplink individual channel transmitter, 61 broadcast information receiver, 62 downlink common channel reception Unit, 63 downlink dedicated channel receiving unit, 64 QoS parameter mapping unit, 65 congestion control unit, 66 radio resource management unit, 67 core network protocol processing unit, 68 radio network protocol processing unit.

Claims (1)

A mobile communication system including a mobile communication terminal, a base station that performs radio communication with the terminal, and a base station control device that controls the base station,
The terminal stores a terminal buffer that stores uplink data to be transmitted to the base station, and a buffer state information transmission unit that transmits terminal buffer state information indicating the amount of data accumulated in the terminal buffer to the base station, A data transmission unit for transmitting data to the base station according to an instruction regarding uplink radio resources by the base station,
The base station includes an interference amount measurement unit that measures an interference amount related to a received signal, an interference amount notification unit that notifies the base station controller of the interference amount measured by the interference amount measurement unit, and the terminal buffer state An uplink radio resource instruction unit that receives information and performs scheduling according to the terminal buffer status information to instruct the terminal about uplink radio resources;
It said base station controller, a mobile communication system, characterized in that a maximum interference amount instruction section for instructing the maximum amount of interference the interference amount must not exceed as a result of the scheduling in the base station.

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