WO2000014908A1

WO2000014908A1 - Method for controlling power of communication system

Info

Publication number: WO2000014908A1
Application number: PCT/JP1999/003818
Authority: WO
Inventors: Kazuhito Ishida
Original assignee: Hitachi, Ltd.
Priority date: 1998-09-08
Filing date: 1999-07-15
Publication date: 2000-03-16
Also published as: JP2000091985A

Abstract

One or more code channels for which a required channel quality of first class relative to a low-power channel such as a voice communication channel is determined is established between a base station and a radio terminal. In this state, an additional channel of second class having a channel quality request value higher than that of the code channel, for example, a high-speed data channel is set up. The radio terminal or base station determines the transmission power value of this second-class channel in such a way that the value is lower than the transmission power value not influencing the first class channel quality which is set up according to the power distribution based on the current interference level. After the set up of the radio channel, the transmission rate and transmission power are gradually increased while monitoring the interference levels of the other channels to the values which fulfill the required channel quality of second class.

Description

Description Power control method for communication systems

The present invention relates to a power control method for a CDMA (CODE D IVISION MULTIPLE ACCESS) wireless communication system. In particular, it relates to a power control method for a CDMA system in which channels having different desired channel qualities coexist.

Background art

Standards Proposal No. 3693, Proposed Upgrade of Interim Standard TIA / EIA / IS-95-A, TSB74, and ANSI submitted by the United States TI A (Telecommunication Industry Association) on December 12, 1997, for a standardization vote -J -STD-008 to an A SI / TI A / E IA Standard Mobile Station-Base Stati on Compatibility standard for Dual Mode Wideband Spread Spectrum Cellular Systems (To Be Published as TIA / EIA- 95-B) According to the report, conventional CDMA systems such as the IS-95 series are designed for voice communication, and data communication is operated under the same communication line quality.

Hereinafter, the power control method will be described. In the uplink (reverse link), the method of estimating the amount of radio wave attenuation from the received electric field strength of the base station radio wave received by the mobile station and setting the transmission power of the mobile station and the method of transmitting the signal transmitted by the mobile station are described. The base station that receives the signal measures its Eb / No (signal power / noise power density per bit) and adjusts the transmission power of the mobile terminal by a command on the downlink (base station transmission). Used.

In the downlink (forward link), the mobile station receiving the signal of the base station measures its FER (Frame Error Rate), transmits the value on the uplink, and the base station transmits the transmission power based on the FER value. Is adjusted.

A similar procedure is taken for data communication, and the wireless interface Above, both voice and data are operated under uniform desired circuit quality quantified by Eb / No or FER. Therefore, the data transmission speed is almost the same as that of voice.For example, in the case of transmission at 76.8 kbps, a method such as multiplexing eight 9.6 kbps voice lines under FER = 1% line quality conditions Is adopted.

Generally, the desired line quality differs between voice communication and data communication. For example, in the case of voice communication, the desired BER (Bit Error Rate) is less than 10-3, and that in the evening is less than 10-3 to 10-6. For audio signals with a maximum transmission rate of 9.6 kbps to 14.4 kbps, the target value for data is set to 2.4½3 to 1445, or higher. Also, the line mode can be a circuit-switched mode or a pocket mode. Therefore, Eb / No for data communication is considered to require a high value equal to or higher than that of voice, and if the communication quality of data communication is to be ensured, it will adversely affect the quality of circuits with weak transmission power such as voice communication. Will be given.

However, in the above-mentioned conventional technology, when the voice line and the data line coexist in the same cell or sector, stable system operation is not taken into consideration. It will affect the communication line.

Accordingly, an object of the present invention is to provide a radio base station and a power control method of a CDMA system that solve the above-mentioned problems of the related art.

Specifically, it can maximize the throughput of the entire system against dynamic voice and data traffic.

An object of the present invention is to provide a radio base station and a power control method for the system A.

Also, even if data communication and voice communication requiring high communication quality are performed by different terminals in the same cell or the same sector, the data communication line is not used for voice communication. To provide a radio base station and a power control method for a CDMA system in which the adverse effect on the link for transmission is minimized. is there. Disclosure of the invention

The present invention sets the power setting for new calls based on line quality under conditions that are vulnerable to interference such as voice. That is, for a high-quality line such as data, transmission power is set from a specified value calculated based on ensuring voice line quality. The increase of the transmission power of the high-quality data link is controlled gradually to a value that satisfies the specified transmission rate and quality of the link while monitoring the quality of the voice link.

Specifically, first, the base station determines in advance the allowable line transmission power according to the line class corresponding to the service condition. The base station monitors the line status of the uplink / downlink CMA channel from time to time, measures the Eb / No and FER (Frame Error Rate) of the existing line, and monitors the calls that may be newly set, such as voice and data. The line conditions of the code channel corresponding to the service conditions (eg, allowable transmission power) are updated as needed.

When a new call is a bucket data communication service that requires higher line quality and lower FER than voice lines, transmission timing and transmission rate negotiation are performed between the base station and the wireless terminal when setting up the line. Will be

As described above, the base station sets the channel conditions of the code channel in advance, and sets a more suitable transmission / reception state with the wireless terminal according to the current traffic density and the waiting packet.

When there is a call request for data communication from the wireless terminal, the base station notifies the wireless terminal of the transmission timing, transmission rate, and transmission power.

Here, for the power transmitted by the base station and the wireless terminal at the time of data communication, the optimum value and margin at the time of collection of the parameter are obtained from the parameters collected by the channel monitor in the base station in advance. Transmission conditions (transmission power and timing) are determined based on this data. Therefore, since the initial transmission data rate is low in the base station or the radio terminal, the transmission power is set to be considerably lower than the specified transmission conditions, and the data transmission is started.

With the start of transmission by the base station or wireless terminal, the base station or wireless terminal increases transmission power or transmission rate while monitoring Eb / No in code channel units. When the system capacity limit or a preset data channel capacity is reached, the increase in transmission power or transmission speed is stopped. If there is a request to generate a new call in that state, the transmission power / transmission rate of the existing data line may be reduced, or the request to set up a new call may be rejected.

When setting a priority call at the capacity limit, lower the power of the data line.In other words, if a high-quality data line exists first, if there is enough capacity, a new voice line can be set. good. In this case, if the priority of the voice line is equal to or lower than that of the data line, the existing line has priority. If the voice line is prioritized, lower the transmission power of the data line to a level at which the voice line can operate stably and set up a new voice line. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a communication system of the present invention. FIG. 2 is a diagram showing a wireless base station according to the present invention. FIG. 3 is a diagram showing a wireless terminal of the present invention. FIG. 4 is a diagram showing a table of desired line quality and line state according to the present invention. FIG. 5 is a diagram showing a line state table and an allowable transmission power value table of the present invention. FIG. 6 is a diagram showing a transmission level management table of the present invention. FIG. 7 is a diagram showing a base station power control function block. FIG. 8 is a diagram showing a base station power control function block. FIG. 9 is a diagram showing a wireless terminal power control function block. Figure 10 shows MS originating / sending FIG. 9 is a diagram showing a flowchart of a BS operation at the time of communication. FIG. 11 is a diagram showing a flowchart of the BS operation at the time of calling / transmitting the ^ side. FIG. 12 is a diagram showing a flow chart of the BS operation at the time of calling an MS priority call. FIG. 13 is a diagram showing transmission power distribution below the BS. FIG. 14 is a diagram showing an example of a control channel frame format. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail using examples.

(Example 1)

FIG. 1 shows an outline of a communication system to which the present invention is applied. The communication system according to the present invention includes a mobile switching center (MSC) 901 that controls a base station (BS), a BS 902 controlled by the MSC 901, and wireless terminals 903, 904, and 905 that communicate with the BS 902. The service area of BS902 is 910. In this configuration, a description will be given of a case where the wireless terminals 903 and 904 have already communicated with the wireless base station 902 and also the wireless terminal 905 starts communication. It is assumed that voice communication that does not need to be high is performed, and the wireless terminal 905 performs data communication that requires higher line quality than voice communication.

FIG. 2 shows a configuration example of the wireless base station 902 of the present invention. Radio base station 902 includes reception section 1301, transmission section 1302, line monitoring section 1310, control section 1320, and storage section 1330. The line monitor unit 1310 has an Eb / ΝΟ measurement unit 1311, and a FER measurement unit 1312. Further, control section 1320 includes uplink transmission rate determining section 1321, uplink allowable transmission power value determining section 1322, other channel interference monitoring section 1323, uplink transmission level determining section 1324, control information creating section 1325, downlink transmission rate determining section 1326 And a downlink allowable transmission power value determining unit 1329. The storage unit 1330 stores parameters required for control in a storage format such as a table. FIG. 3 shows a configuration example of the wireless terminals 903 to 905 of the present invention. The wireless terminal includes a receiving unit 1401, a transmitting unit 1402, an Eb / NO measuring unit 1411, a FER measuring unit 1412, and a control unit 1420. The control unit 1420 includes an uplink channel creation unit 1425 and a power control command extraction unit 1428.

FIG. 4 shows a table for storing the desired line quality and the current line state for each wireless terminal. The table shows the MS identification information 1101, and the user-desired line quality 1 1 10 as Eb / N 01 1 1 1 and FER 1 112. The maximum transmit power value that the transmitter can transmit 11 13 and the transmission rate 1 114 Is stored. Further, in this table 1100, Eb / N01111, FER111, actual transmission power value 1113, and transmission rate 1114 are stored as actual line conditions. These are further stored for each of the uplink channel and the downlink channel, and thus for each of a plurality of code channels in the uplink channel.

FIG. 5 shows a table 1200 showing the current line state in more detail, and a table 1500 of the transmission power allowable value for each line quality class. Further, FIG. 5 also shows how a table 1500 of transmission power allowable values for each line quality class is created from the parameters of the line state table 1200. The line state table includes, as line states for each uplink and downlink, downlink Eb / N01210, downlink FER1211, other information such as interference value 1212, uplink Eb / N01220, uplink FER1221, and other information 1222 such as interference value. Is stored. These may also be stored for each of a plurality of code channels. The transmission power allowable value table 1500 has a line quality class 1501, a transmission power level 1502, a downlink allowable transmission power value 1503, and an uplink allowable transmission power value 1504. It is assumed that one class has multiple levels.

FIG. 6 shows a table 1000 of transmission power levels. The table 1000 includes a line quality class 1001, a transmission power level 1002, and a flag section 1003 indicating which level is set as a specified value or an initial value. Is shown.

4 to 6 show tables, each parameter may be managed in a format (pointer, structure, etc.) other than tables. The point is that it is only necessary to be able to manage the status of each wireless terminal, so the storage format is not important. Hereinafter, embodiments of the invention will be described with reference to these drawings.

First, an uplink channel transmission power control method will be described. Before the communication of the wireless terminal 905 is started, the wireless base station 902 receives the upstream signal of the wireless terminals 903 and 904 in the receiving unit 1301, performs necessary frequency conversion, demodulation and decoding, and performs line monitoring. The Eb / No measuring unit 131 1 measures Eb / No, and the FER measuring unit 1312 measures FER. In addition, the control unit 1320 creates the table 1120 (or 1200) in association with each measured value and each wireless terminal, and stores the table 1120 (or 1200) in the storage unit 1330.

Next, the wireless terminal 905 makes or makes a call so as to start communication. At this time, since the communication type is data, the uplink transmission level determination unit 1324 refers to the table 1000 stored in the storage unit 1330, obtains a specified value 1002 of the transmission level, and obtains the obtained specified value. The permissible transmission power value 1504 for data communication corresponding to 1002 is obtained from the table 1500. The allowable transmission power value 1500 is determined based on the uplink allowable transmission power value determining unit 1322 EEb / No or the like, and is stored in the storage unit 1330 as the table 1500.

Further, uplink transmission level determination section 1324 determines a value several levels lower than the allowable transmission power value obtained from table 1500 as an initial value (initial power transmission value), and uses the determined value as control information creation section 1325. Send to Here, the reason why the value is set to be several levels lower is to prevent the wireless terminals 903 and 904, which are already in communication, from performing voice communication, and thus not affect those with low line quality. .

The control information creation unit 1352 creates control information including the initial transmission power value. I do. The control information creation unit 1352 usually creates a command to increase or decrease the power by one step. Subsequently, transmitting section 1302 transmits this control information to wireless terminal 905 on the control channel. Note that FIG. 6 shows a state in which the initial value several levels below the specified value is selected, and the transmission power is increased so as to reach the specified value in one step.

In the wireless terminal 905, the control channel is received and demodulated by the receiving unit 1401, and the initial transmission power value is extracted by the power control command extracting unit 1428 of the control unit 1420. Subsequently, transmitting section 1402 starts transmission of the uplink channel with the extracted initial power control value. Note that the power control command extraction unit 1428 normally extracts a command to increase or decrease the power by one step.

In the radio base station 902, the uplink channel of the radio terminal 905 is received by the receiving unit 1301, the Eb / No is measured by the Eb / No measuring unit 1311, the FER is measured by the FER measuring unit 1312, and the result is stored in the table 1200 (1120). It is stored as the upstream Eb / Nol 220 (1121) and the upstream FER1221 C1 122). The other channel interference monitoring unit 1323 measures the interference value that the uplink channel transmitted by the wireless terminal 905 gives to the wireless terminals 903 and 904, and compares this interference value with a predetermined threshold. As a result of the comparison, when the interference value is equal to or less than the threshold value and the Eb / No and FER of the wireless terminal 905 are better than the desired values 1111 and 1112, the transmission rate determination unit 1321 determines the transmission rate. It is raised gradually until the user's requirements are met. If any of the interference value, Eb / No, and FER become worse than the threshold value in the process of increasing stepwise, stop the increase, reduce the transmission rate, and adjust the interference value, Eb / No, and FER. Try to meet.

If the Eb / No and FER of the wireless terminal 905 are degraded from desired values even if the interference value is equal to or less than the threshold, and the transmission rate required by the user has not been reached, the uplink transmission level The decision unit 1324 decides to increase the uplink transmission power value of the MS905 by one level. The uplink transmission power value of the MS determined by the uplink transmission level determination unit 1324 is transmitted to the wireless terminal 905 by the method described above, and the The control unit 1420 of the received wireless terminal 905 increases the transmission power by one level and transmits the uplink channel. In the same way, the power control is performed until the transmission rate required by the user is reached while satisfying the interference value, Eb / No, and FER.

Next, a downlink channel power control method will be described.

The Eb / No measuring unit 141 1 and the FER measuring unit 1412 of the communicating wireless terminals 903 and 904 measure the Eb / No and FER of the downlink channel transmitted by the radio base station 902, and report the measurement result to the uplink CH. The creation unit puts it on the uplink channel, and transmits from transmission unit 1402 to radio base station 905. Upon receiving the report, the wireless base station 902 stores the measurement results 1210 and 121 1 of each wireless terminal as a table 1200 in the storage unit 1330.

The allowable downlink transmission power value determining unit 1329 refers to the table 1200 stored in the storage unit 1330 and determines the allowable transmission power value 1503 of the downlink channel for each communication type. Note that the specified value for each communication type is determined using table 1000 as in the case of the uplink. The downlink transmission level determining unit 1328 sets the downlink transmission level of the wireless terminal 905 (in this case, the initial value) to a level that is several levels lower than the allowable transmission power value (specified value) determined by the downlink allowable transmission power value determining unit 1329. Set to. Transmitting section 1302 transmits the downlink channel to wireless terminal 905 at the transmission level determined by the allowable downlink transmission power value determining section. Note that reference numeral 1003 in Fig. 6 indicates that the current level is the specified value or the initial value by setting a flag so that it can be grasped.

The radio terminal 905 measures the Eb / No, FER, and interference value for the downlink channel transmitted by the radio base station 902, and reports the measurement result to the radio base station 902 via the uplink channel. Upon receiving the report, the wireless base station 902 stores the measurement result of the wireless terminal 905 in the table 1200 in the storage unit 1330 as the downlink Eb / Nol 210 downlink FER 1211. When transmitting the interference value, it is stored in 1212 or the like. The radio base station 902 estimates an interference value given to the downlink channels of the radio terminals 903 and 904 by the downlink channel transmitted to the radio terminal 905, and compares the interference value with a predetermined threshold value. As a result of the comparison, when the interference value is equal to or less than the threshold value and the Eb / No and FER of the downlink channel of the radio terminal 905 are better than desired values, the transmission rate determination unit 1326 sets the transmission rate It is raised gradually until the required value is satisfied. If any of the interference value, Eb / No, and FER become worse than the threshold value in the process of gradually increasing the value, stop the increase, reduce the transmission speed, and satisfy the interference value, Eb / No, and FER. To do.

If the Eb / No and FER of the wireless terminal 905 are degraded from desired values even if the interference value is equal to or less than the threshold value, and the transmission rate required by the user has not been reached, the downlink transmission level The deciding unit 1328 decides to increase the BS transmission power value by one step. Transmitting section 1302 transmits the downlink channel with the downlink transmission power value determined by downlink transmission level determining section 1328. After that, in the same way, while satisfying the interference value, Eb / No, and FER, the transmission power control of the down channel is performed until the transmission rate required by the user is reached.

(Example 2)

Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

Fig. 5 shows an example of the configuration of BS902. The BS 902 of the present invention includes a BS reception RF7ANT unit 501, a BS demodulation unit 502, a BS decoding unit 503, a BS audio / de-night processing and layer 2, 3 processing unit 504, and a BS audio / data processing unit. 505, a BS uplink link FER determination section 506, a BS call control section 507, a BS QoS / priority control section 508, a BS voice / data processing section 509, a BS management section 510, and a BS encoding section 511. , A BS modulation section 512, a BS transmission RF / ANT section 513, a BS uplink link Eb / No determination section 514, a BS downlink power control section 515, and a BS RF power control section 516.

Figure 8 shows an example of the configuration of the MSC901. MSC901 performs signal exchange connection It comprises a switching unit 521 and a mobility management unit 522 for performing call control and mobile object management.

FIG. 9 shows a configuration example of the wireless terminals 903 and 904 of the present invention. The wireless terminal of the present invention includes an MS man-machine interface 601, an MS voice / data processing unit 602, an MS encoding unit 603, an MS modulation unit 604, an MS transmission RF / ANT unit 605, and an MS reception RF. / ANT section 606, MS demodulation section 607, MS decoding section 608, MS downlink Eb / No determination section 609, MS QoS Quality of Service) / priority control section 610, and MS downlink link FER It comprises a judgment unit 611 and an MS management unit 612. In FIGS. 7 and 8, a solid line indicates a control signal, and a broken line indicates a traffic signal (communication information).

In this example, in order to control the transmission power from the MS, the BS measures the Eb / No based on the received signal from the MS, inserts a power control bit for the MS into a downlink channel, and controls the transmission power of the MS. Is going. Similarly, in order to control the transmission power from the BS to a specific MS, the MS measures the Eb / No based on the received signal from the BS, inserts a power control bit into the uplink channel, and The BS transmits and controls the transmission power for a specific MS based on the Eb / No from the MS. First, the operation of the BS when a call with a high line quality class is originated from the MS will be described with reference to FIGS.

The outgoing call is started by a key input from a man-machine interface (MMI) (601). The signal is subjected to framing in the voice / data processing unit (602). At this time, attributes related to line quality and priority control are added from the QoS (Quality of Service) / priority control unit (610). In addition, information relating to the transmittable power value of the MS and the transmission speed to be transmitted, which are managed by the management unit (612), are added to the information.

In the coding unit (603), the signal output from the voice / data processing unit (602) is subjected to channel coding such as interleave error correction coding. The signal output from the encoding unit (603) is subjected to information modulation and spread modulation of the signal by CDMA in the modulation unit (604). The spread signal is transmitted to the BS via the transmission RF / ANT unit (605) on the uplink. The access method used here is generally a random access method.

The signal received by the BS RF / ANT unit (501) is subjected to spread demodulation and information demodulation by the demodulation unit (502). The demodulated received signal, that is, the random access signal, is decoded by the decoding unit (503), and then transmitted to the voice / data processing and layer 2 and 3 processing unit (hereinafter, VDLP) (504). The uplink link FER determination unit (506) checks for frame errors, determines the MS service attributes (voice, data, line quality, priority, etc.), authenticates, and checks location information. It is. That is, the received signal is decomposed into frames by the voice / data processing unit (505), and the above-mentioned information is confirmed by the call control unit (507).

Some information is sent and received to link systems such as the mobile switching system (MSC) (520). The MSC includes a switching unit (Switch) (521) and a call control / mobility management unit (Call CTRL and Mobility Management) (522). The switching unit (521) transmits traffic information and the call control / mobility management unit (522). ) Performs processing such as call control, mobility management, and authentication. When accepting a call from the MS, the data such as the line quality and the priority order are stored in the QoS / priority control unit (508) of the BS, and are controlled in conjunction with the call control.

When access from the MS is permitted from the BS and the NW, the BS allocates a channel to the MS. In CDMA, this allocation is determined by parameters such as code, frequency, transmission timing, and transmission power and transmission rate, depending on the service request from the MS.

The negotiation between the BS and the MS is performed by the management part (612) of the MS, the QoS / priority control part (610), the call control part (507) of the BS, the QoS / priority control part (508), and the management part (508). 510). When there is a transmission request from the MS, the BS allocates a line in the following procedure. The BS also monitors signals of other MS channels. The total power value received by the BS is monitored by the RF power control unit (516) as the total received power in the RF / ANT unit (501). Each reception channel is demodulated for each code channel by the demodulation unit (502), and an interference value according to the desired channel quality of the channel is estimated and updated as needed. The monitoring of these parameters is performed by the management department (510). When a new call request is made, the QoS / priority control unit (508) uses the parameters determined by the management unit (510) based on the line quality request and the appropriate appropriate Eb / No value. Is set, and an algorithm in case of change is prepared. When transmitting a control message, the message is inserted in the voice / data processing unit (509) via the call control unit (507) and transmitted to the MS.

After the line is allocated, the MS starts transmission at the specified timing and transmission rate.

The signal received from the MS is monitored as needed by the BS, and the uplink link F ER measurement unit (506) measures the FER to check the quality. The QoS / priority control unit (508) sets priorities according to the desired line quality and assigns appropriate interference conditions to the lines. For those that do not satisfy the desired channel quality, the transmission power of the MS and the power associated with the control information from the BS so that the required value is achieved as long as the interference conditions with other channels at the BS are satisfied. And control the transmission rate. This control is performed by controlling the transmission rate using the control channel shown in Fig. 14, in addition to the closed-loop power control between the MS and BS, which involves changing the reference Eb / No. However, at this time, the management unit (510) and the QoS / priority control unit (508) are controlled so that the interference conditions of other lines, including those with a low line class, do not fall below the specified values (106-125). .

Next, based on the example in Fig. 11, a call originating from the BS with a high line quality class The operations of BS and MS will be described with reference to FIGS.

The call is initiated by a request from the NW system.

The signal is subjected to framing in the voice / data processing unit (509). At this time, attributes relating to the line quality and priority control are added from the QoS / priority control unit (508) _(In addition, these information is managed by the management unit (510). The signal from the voice / data processing and layer 2 and 3 processing unit (hereinafter referred to as VDLP) (504) is sent to the encoding unit (511), where it is interleaved and error-corrected. Channel information such as encoding is performed.-Information modulation of signal by CDMA Modulates and spread-modulates the output from encoding unit (511) in Z-spreading modulation unit (512). Sent to the MS on the downlink via the / ANT section (513).

This section describes how to distribute downlink power.

The operation of the RF power control unit (516) is related to the downlink power control unit (515), and power control for each line (code channel) is performed by the downlink power control unit (515). Is performed by the RF power control unit (516). All control information is monitored by the management unit (510). That is, the transmission power of the BS is allocated by a predetermined power distribution value or power ratio shown in FIG. 13, and the transmission power of the entire BS is controlled by the RF power control unit (516). The power control on a per-cell basis is performed by the downstream power control unit (515), and the balance is monitored by the management unit (510).

Also, based on the downlink monitor information of each MS collected on the uplink, the interference state at each MS is monitored, and the monitored interference state is reflected as a control parameter of the downlink power by the management unit (510). ing.

If bidirectional communication is possible, MS can measure downlink FER, and if downlink power can be adjusted by transmitting the measured FER as a power control bit on the uplink, And the line quality by FER in FIG. A confirmation is made.

On the other hand, in the case of one-way communication using only BS transmission, transmission is performed from the BS to the MS based on the power distribution value shown in Fig. 13, and the interference level of the other channel is monitored. Increase or decrease.

A configuration example of the control channel will be described. This example is a downlink example. The reservation channel response frame signal (701) is an MS-ID for identifying an MS, a Message-Type indicating a communication type, a Reservation-Packet-Sequence-Number indicating a reservation bucket order, and an initial transmission power Initial-Tx. -Pw, transmission timing Consists of Tx Timing.

The transmission rate control frame signal (702) includes MS-ID, which is information for identifying the MS, Message-Type, which indicates a communication type, and Reservation-Packet-Serquence-Number, which indicates the order of reservation packets. It is composed of QoS / CH_Class indicating the service class and Rate-Control-Command indicating the transmission speed. After adding CRC / Tail Bits for coding (703), convolutional coding and interleaving are performed (704), a power control signal is added (705), and reassembled into a 20 ms frame for transmission. (706) (707).

FIG. 10 is a diagram illustrating the operation of a base station (BS) when a wireless terminal (MS) performs a calling and transmitting operation.

In the main line setup between BS and MS, the line quality class 1 ((9.6 kbps voice line; target FER = 0.01)) is used to set the line quality class 2 (64 kbps data; target FER Suppose that a new line is set up (= 0.0001).

The BS measures Eb / o (signal power / noise power density per bit) from the total received power and the received power from each MS between one or more MSs that set up the line, This is used as an index of line quality (101). At this time, the transmission speed and line quality are set based on the 9.6 kbps voice line; target FER-0.01. In the case of circuit switching, eight 9.6 kbps lines are required for 64 kbps transmission. Yes, corresponding power is required to satisfy Eb / No.

In addition, a target transmission power control value is set using Eb / No for each desired channel quality (102).

When a call originates from an MS (103), it is not a voice line (eg, 9.6 kbps, FER = 0.01), but is a Class 2 data transmission requiring a higher transmission rate and a lower error rate. In the case of a line (eg, 64 kbps, FER = 0.0001), negotiation for line setting is usually performed between the MS and BS (104). In this case, a higher FER is required, so the transmission power needs to be further increased to obtain a higher Eb / No. This negotiation responds to transmission requests (transmission speed, line quality, delay requests, etc.) from the MS, and the BS responds to transmission requests from the line congestion state so that the entire system can operate stably within the capacity. To set appropriate transmission power and transmission timing.

FIG. 14 shows a control channel configuration example for negotiation.

When the line is reserved by this negotiation (105), the MS starts transmission based on the reservation information.

Now, the Eb / No of the base station is associated with the channel quality class 2 and is set to the nth level which is lower than the level that completely satisfies the channel quality class 2. In this example, we assumed level 1 of circuit class 2 (high-speed data) (106).

This line is first controlled by this Eb / No. That is, it is determined whether or not the reception Eb / No satisfies the n-th level of class 2 (107). If not, the process returns to step (104), and the negotiation between the BS and the MS is executed again. Here, when setting up a high-quality line, in order to sufficiently follow sudden changes in the wireless line, a margin is given to the existing line, and a stable system operation is performed while monitoring the line condition. Do. Here, margin refers to a power margin that does not adversely affect other line quality. The BS collects the line status with other MSs as needed by receiving the uplink channel from each MS.

In step (107), if the condition is satisfied, it is determined whether or not the interference level of another channel satisfies the specified value for the newly generated call (108). If the default value is not satisfied, the process returns to step (104), and the negotiation between the BS and MS is executed again.

If the predetermined value is satisfied in step (109), the BS measures FER of the signal from the MS (109). In the present invention, since the interference control between channels is controlled with the first priority, if the FER measured in step (109) does not satisfy the predetermined value, an operation to reduce the transmission speed of the MS and suppress the occurrence of errors is performed (1). Ten ). The control of the transmission rate to the MS uses, for example, the control channel format shown in FIG.

If the FER measured in step (109) satisfies the specified value, it is checked whether the transmission rate satisfies the user required value (MS required value) (111). If the required values are satisfied, the system enters the steady operation mode (1 12). In this state, the line quality conditions requested by the user are satisfied, and no problems occur with other lines in the system.

If the MS does not meet this requirement in step (11 1), the level of Eb / N'o is changed to determine whether the power increase is necessary or not and the MS can do so (113). _c If it is determined that the power increase is not required, the MS is instructed to increase the transmission rate (114). To change the transmission rate, the BS calculates the power margin value from the Eb / No and FER of the received signal and converts it to a transmission rate, so that the BS notifies the MS of the allowable value of the transmission rate. For example, change the spreading gain to increase the transmission speed. Since this control is performed under constant power control conditions, quick feedback control to the MS using a dedicated control channel as shown in Fig. 14 is desirable. If the BS determines that the received electric field fluctuates greatly due to fading and the transmission rate control cannot keep up with the fading fluctuation, The line quality may be operated only by power control without controlling the transmission rate. (On the other hand, if it is determined that the power needs to be increased, whether the Eb / No level should be changed to n + 1 (1 15) The most efficient value in the system operation is adopted as the difference between the n-level and the n ÷ l-level. Thus, the n-level is controlled so as to gradually increase by s. The MS increases the transmission power as a result of the power control loop with the BS.

This Eb / No value is determined from the change characteristics of the received Eb / No and the estimated capacity from interference from other channels. A series of processes (117-125) of power control, interference measurement, Eb / No measurement, and speed control from here is the same as when the reference Eb / No is at the n level. However, if the received Eb / No or interference to other channels exceeds the allowable value at one level, the power is reduced to n levels (ri = n-

1) Restart the operation (118). This series of power control is performed until the required transmission rate is satisfied under the required line quality.

These series of processes apply equally well when the number of circuit quality classes exceeds two. If the line level is higher than 2, different initial Eb / N'o values (106) and line quality, transmission speed, and standard Eb / No levels when set to the steady operation mode (1 12) (N) is set.

Figure 11 shows the BS operation when a call is originated from the network side (Nff) and an incoming call is transmitted to the MS accommodated by the BS.

The measurement of the Eb / No of the set line is performed by receiving a signal including the Eb / No measured by the MS and grasping the line state (201).

The Eb / No of the line to be set is set for each desired line quality (202). An example of a power setting method at this time will be described later with reference to FIG.

In the downlink, it is assumed that a new channel of class 2 (64 kbps data transmission) is set by calling from the NW (203). At this time, the transmission speed and line quality are set based on the 9.6 kbps voice line; target FER = 0.01. If circuit switching is the basis, eight 9.6 kbps lines are required for 64 kbps transmission, and corresponding power is required to satisfy Eb / No.

The BS calls the MS, negotiates the contents related to the line quality, such as the requested transmission speed and transmission quality from, and the reception timing, and reserves the line (204).

When the line can be reserved (205), the BS starts transmission at the n-th level transmission power according to the reserved timing and conditions (206).

The BS monitors not only this new call but also all signals from other lines that have already been set up. That is, the downlink signal quality transmitted by the BS is received by the MS, and the channel quality is transmitted from the MS to the BS as power control and other control information. The BS monitors the result as needed. I have.

When transmitting, the BS checks whether the transmission power satisfies the power setting value (202) predetermined for each desired channel quality (208). Here, if the interference exceeds the specified value based on the monitor information from another MS, the negotiation is executed again (204). If the interference level is equal to or less than the specified value, it is checked from the monitoring information from the MS whether the downlink FER satisfies the specified value (209). If the user is not satisfied, an operation for reducing the transmission speed of the downlink is performed (210). If so, it checks whether the transmission rate satisfies the user's requirement (211). If this is satisfied, it enters the normal operation mode (212). In this state, the line quality conditions requested by the user are satisfied, and no problems occur with other lines in the system.

If the transmission speed is lower than the user request value, the necessity of power increase is confirmed (213).

If it is not necessary to increase the power, the transmission speed of the downlink is increased (214), and the FER is checked. If it is determined that the power needs to be increased, the BS increases the reference power. And start transmission (215). The transmission power level here is n + 1 level. The difference between the n + 1 level and the n level uses the most efficient value in system operation. As described above, in the present invention, the value of EbZNo is gradually increased, so that the call request is monitored while monitoring the effect on other lines that are already in communication, especially voice lines with low transmission power. Is controlled so as to provide transmission power step by step to satisfy This value is calculated from the downlink transmission power distribution shown in Fig. 13 and the capacity estimate from the interference of other MS channels.

A series of subsequent steps (216-223) of power control, interference measurement, Eb / No measurement, and transmission speed control are the same as those for the transmission power n level. However, if the transmission power or interference to other channels exceeds the specified value at the n + 1 level, the power is reduced to the n level and operation resumes (218).

This series of power control is performed until the required transmission rate is satisfied under the required line quality.

These series of processes apply equally well when the number of circuit quality classes exceeds two. However, the line quality, transmission speed, and power value for setting the initial transmission power value (206) and the steady operation mode (212) are set separately. FIG. 12 shows an example in which a priority call is issued from the MS in the example shown in FIG. 10 and control is performed.

In this example, the setting of other lines is changed if necessary in accordance with the outgoing call of the priority call, and more advantageous line setting conditions and power setting conditions are provided. Other controls are the same as in the example shown in FIG.

The BS monitors the status of the set line and calculates the Eb / No when setting up a new line in advance (301, 302).

There is a priority call from the MS (303).

The BS checks the order of priority calls from the MS (304). Compare the priority of the set line and the line in the setting waiting state, and change the setting of other lines if necessary. Therefore, it is necessary to confirm whether the setting change of other lines is necessary (329), and if necessary, confirm whether or not it is possible (305). If it is not possible, after a certain waiting state (306), check the priority (304). ) Is performed again.

If the setting of another line can be changed, the change is made (307), and based on the information, the line is reserved between the MS and BS (308).

If the line reservation cannot be made, an inquiry (305) for changing the setting of another line is made again, and the line is preferentially allocated. If the line reservation is 0K, the nth level Eb / No for the priority call is set and transmission starts (310).

The power control thereafter is the same as in Fig. 10 (310-328) until it enters the steady operation mode (316).

FIG. 13 is an example showing a method for allocating power in a downlink channel. The horizontal axis shows the number of lines (TCHV links) normalized by the voice channel power, and the vertical axis shows the transmission power. In this example, the pilot power (401), the overhead channel power (402) for transmitting control signals, the voice channel power (403), and the data channel power are calculated in advance at a fixed ratio. It is operated by dividing.

These division ratios are determined by the occurrence of traffic and interference characteristics. Of course, this ratio, especially the power distribution ratio for voice channels and data channels, may be distributed dynamically. In any case, these are preset in order to facilitate interference control.

The measurement of the interference power at the BS in Figs. 10, 11, and 12 is performed to set up a stable channel within these distribution ratios. The power control according to the present invention is applied to the subsequent processes, and is executed to perform stable interference control between these channels having different line qualities. In addition, the pilot power and the overhead channel power are controlled so as to satisfy a predetermined power ratio with respect to the required transmission power of the voice or data channel. As described above, according to the present invention, even if the radio wave propagation environment is rapidly deteriorated, a stable voice and high-quality data line can coexist within the system capacity range without sacrificing the voice line that is vulnerable to interference. System operation becomes possible.

Further, according to the present invention, the transmission power setting method is based on a line having a weak interference condition, and stable operation of a data line having a line quality different from that of a voice line becomes possible.

Claims

The scope of the claims

1. A power control method for a wireless communication system including a plurality of wireless terminals and a wireless base station capable of wirelessly communicating with the plurality of wireless terminals,

The wireless base station is preset with a plurality of line quality conditions selected in response to a call request from the plurality of wireless terminals,

The radio base station, when receiving a call request with a predetermined transmission rate as a request value from the plurality of radio terminals, a transmission power satisfying a line quality condition selected from the preset line quality conditions. A transmission power of a lower value to the wireless terminal that has made the call request, receives a signal transmitted from the wireless terminal with the specified transmission power, and transmits a transmission rate of the received signal. Control method for a communication system, characterized by instructing the wireless terminal that has made the call request to gradually raise the power.

2. The power control method for a communication system according to claim 1, wherein each of the line quality conditions includes a value of a transmission power serving as a reference of transmission power instructing a wireless terminal that has made the call request. A power control method for a communication system, wherein

3. The power control method for a communication system according to claim 2, wherein, when a new call request is received from the wireless terminal, the wireless base station communicates with the wireless terminal in response to the call request. Determine the timing, transmission speed, and transmission power of the line used in the above, set the line with the wireless terminal at a value lower than the determined transmission speed and transmission power, and respond to the newly received call request. If the error rate measured by another wireless terminal communicating with the wireless base station exceeds a predetermined value due to the wireless line set up between the wireless terminal and the wireless terminal that has made the new call request again, A power control method for a communication system, comprising: determining a timing, a transmission rate, and a transmission power of a line used in the communication system.

4. The power control method for a communication system according to claim 1, wherein the transmission speed from the radio base station to the radio terminal that has made the call request is increased. The power control method for a communication system is characterized in that the instruction to perform is performed in a state where the error rate of the received signal is equal to or less than the error rate of the call request.

5. A power control method for a wireless communication system including a plurality of wireless terminals and a wireless base station capable of wirelessly communicating with the plurality of wireless terminals,

The radio base station, when receiving a call request with a predetermined transmission rate as a request value from the plurality of radio terminals, a transmission power satisfying a line quality condition selected from the preset line quality conditions. A transmission power of a lower value is instructed to the wireless terminal that has made the call request, a signal transmitted from the wireless terminal is received by the instructed transmission power, and a transmission speed of the received signal is reduced. If the transmission rate included in the call request is not satisfied, the wireless terminal that issued the call request is instructed to gradually increase the transmission power so as to satisfy the transmission rate included in the call request. A power control method for a communication system.

6. The power control method for a communication system according to claim 5, wherein each of the line quality conditions includes a value of a transmission power serving as a reference of a transmission power instructed to the wireless terminal that has made the call request. A power control method for a communication system, wherein

7. The power control method for a communication system according to claim 6, wherein, when a new call request is received from the wireless terminal, the wireless base station communicates with the wireless terminal in response to the call request. Determine the timing, transmission speed and transmission power of the line used between the terminals, set the line with the wireless terminal at a value lower than the determined transmission speed and transmission power, and respond to the newly received call request. If the error rate measured by another wireless terminal communicating with the wireless base station by the wireless line set accordingly exceeds a predetermined value, the new call request is issued again. A power control method for a communication system, comprising: determining a timing, a transmission speed, and a transmission power of a line used with a wireless terminal.

8. The power control method for a communication system according to claim 5, wherein the instruction to increase the transmission power from the wireless base station to the wireless terminal that has made the call request is an error rate of the received signal. A power control method for a communication system, the method being performed in a state where the error rate is equal to or less than the error rate of the call request.

9. The power control method for a communication system according to claim 5, wherein the instruction to increase the transmission power is performed in a stepwise manner, and in each of the steps, in another wireless terminal communicating with the wireless base station. A power control method for a communication system, which is performed by confirming that a measured error rate is equal to or less than a predetermined value, and then instructing a next step of transmission power.

10. A power control method for a wireless communication system including a plurality of wireless terminals and a wireless base station capable of wirelessly communicating with the plurality of wireless terminals,

The wireless base station has a plurality of line quality conditions that are selected in response to a call request from the plurality of wireless terminals, and is preset.

The radio base station, when receiving a call request with a predetermined transmission rate as a request value from the plurality of radio terminals, a transmission power satisfying a line quality condition selected from the preset line quality conditions. A transmission power of a lower value is instructed to the wireless terminal that has made the call request, a signal transmitted from the wireless terminal is received with the instructed transmission power, and a transmission rate of the received signal is reduced. After instructing the wireless terminal that has made the call request to gradually increase the transmission rate, and instructing to increase the transmission rate, the transmission rate of the signal received from the wireless terminal is higher than the transmission rate of the call request A power control method for a communication system, comprising: when low, instructing a wireless terminal that has made the call request to gradually increase transmission power so as to satisfy a transmission rate included in the call request.

11. The power control method for a communication system according to claim 10. A power control method for a communication system, characterized in that each of the line quality conditions is associated with a value of transmission power serving as a reference of transmission power instructing the wireless terminal that made the call request. .

12. The power control method for a communication system according to claim 11, wherein the wireless base station, when newly receiving a call request from the wireless terminal, communicates with the wireless terminal in response to the call request. Determine the timing, transmission speed and transmission power of the line used between the terminals, set the line with the wireless terminal at a value lower than the determined transmission speed and transmission power, and set the newly received call request. If the error rate measured by another wireless terminal communicating with the wireless base station by the wireless line set according to the above exceeds a predetermined value, the communication with the wireless terminal that has made the new call request again is performed. A power control method for a communication system, comprising determining a timing, a transmission speed, and a transmission power of a line used between the communication systems.

13. The power control method for a communication system according to claim 10, wherein the instruction to increase the transmission speed from the wireless base station to the wireless terminal that has issued the call request and the transmission power are increased. The instruction is performed in a state where the error rate of the received signal is equal to or less than the error rate of the call request.

14. The power control method for a communication system according to claim 10, wherein the instruction to increase the transmission power is performed stepwise, and in each step, another radio terminal communicating with the radio base station. A power control method for a communication system, comprising: confirming that an error rate measured in step (a) is equal to or less than a predetermined value, and then instructing a next step of transmission power.

15. A power control method for a wireless communication system including a plurality of wireless terminals and a wireless base station capable of wirelessly communicating with the plurality of wireless terminals,

The wireless base station is preset with a plurality of line quality conditions selected in response to a call request from the plurality of wireless terminals, When the radio base station receives a call request that is a new priority call from the radio terminal, the radio base station communicates with another radio line that is already communicating according to the priority of the call request. Change the timing, transmission speed, and transmission power of the line used between the wireless terminal and the wireless terminal that issued the call request, which is the priority call, according to the content of the call request. And transmission power, and a line quality condition selected from the preset line quality conditions is set so as to set the line with the wireless terminal at a value lower than the determined transmission speed and transmission power. Instructing the wireless terminal that has made the call request a transmission power lower than the transmission power that satisfies the condition, receiving a signal transmitted from the wireless terminal with the indicated transmission power, I will gradually increase the transmission speed A power control method for a communication system, comprising: instructing the wireless terminal that has made the call request.

16. The power control method for a communication system according to claim 15, wherein each of the line quality conditions includes a transmission power as a reference of a transmission power instructed to the wireless terminal that has made the call request. A power control method for a communication system that is characterized by being associated with a value.

17. The power control method for a communication system according to claim 16, wherein, when a new call request is received from the wireless terminal, the wireless base station communicates with the wireless terminal in response to the call request. Determine the timing, transmission speed and transmission power of the line used between the terminals, set the line with the wireless terminal at a value lower than the determined transmission speed and transmission power, and set the newly received call request. If the error rate measured by another wireless terminal communicating with the wireless base station by the wireless line set according to the above exceeds a predetermined value, the communication with the wireless terminal that has made the new call request again is performed. A power control method for a communication system, comprising determining a timing, a transmission speed, and a transmission power of a line used between the communication systems.

18. The power control method for a communication system according to claim 15, The instruction to increase the transmission rate from the wireless base station to the wireless terminal that made the call request is issued when the error rate of the received signal is equal to or less than the error rate of the call request. A power control method for a communication system.

19. In a wireless communication system including a plurality of wireless terminals and a wireless base station that communicates with the wireless terminals,

When setting the line of the first wireless terminal requesting high-quality communication, it is preferable to control the transmission power of the first wireless terminal based on the communication quality of the low-quality second wireless terminal. A wireless communication system, characterized by:

20. In a wireless base station that communicates with multiple wireless terminals,

Measuring means for measuring the line quality of the first wireless terminal communicating with the wireless base station;

First determining means for determining an allowable value of transmission power of a second wireless terminal newly starting communication with the wireless base station based on the line quality measured by the measuring means;

A second determining unit that determines an initial value of transmission power at the start of transmission of the second wireless terminal based on the allowable value determined by the first determining unit; and A transmission unit for transmitting command information to the second wireless terminal so that the second wireless terminal transmits according to the initial value.

21. The wireless base station according to claim 20, wherein the wireless base station performs power control such that the transmission power of the second wireless terminal gradually approaches the allowable value from the initial value. A wireless base station characterized by the above-mentioned.