JP2000224103A - Method of supplying radio digital communication service - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an occurrence rate of interruption of communication to the utmost, even when a base station receives increase/decrease requests of transmission power values from terminal stations where the total sum of the transmission power from them exceeds a prescribed maximum power of the base station. SOLUTION: A base station adopting the CDMA system transmits with power respect to plural terminal stations a1-a6 by utilizing the same frequency band. When the base station receives increase/decrease requests of transmission power from the terminal stations, the base station obtains a tentative transmission power by adding an increase/decrease request Di to a current transmission power Pi, selects reject stations in the order of higher transmission power and selects the remaining terminal stations to be permitted stations when the total sum Σ(Pi+Di) exceeds a maximum transmission power M of the base station. The base station reserves the transmission power as requested by selecting power for the permissible stations through the setting of actual transmission power PPi = tentative transmission power (Pi+Di) and selects actual transmission power PPi=0 for the reject stations as a rule, but assigns remaining power to one reject station, when there is remaining power up to the maximum transmission power M.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for providing a wireless digital communication service, and more particularly to a technique for controlling transmission signal power when providing a wireless digital communication service using a code division multiple access system.

[0002]

2. Description of the Related Art With the development of digital technology, a wireless digital system has been widely used as a communication service providing system. In particular, a code division multiple access system (CDMA: Code D
ivision Multiple Access (hereinafter, simply referred to as CDMA system) has attracted attention as a mainstream wireless digital system in the future because it has the advantage of securing a large number of user channels per bandwidth. In a general CDMA system, a service providing area is divided into a plurality of zones, a base station in charge is provided for each zone, and a single base station and a plurality of terminal stations existing in the zone in which the base station is provided are connected. Between them, the same frequency band is shared at the same time and used in multiple access. At this time,
Since encoding is performed using a unique pseudo noise code for each individual user, it is possible to separate the signal for each individual user even if the same frequency band is simultaneously shared by multiple users. . As described above, since the same frequency band can be shared at the same time, a time division multiple access system (TDMA) is used.
), The advantage of securing more user channels per bandwidth can be obtained.

[0003] Each terminal station used in this CDMA system receives a request for increasing or decreasing the transmission signal power destined for itself so that it can receive power suitable for maintaining a predetermined communication quality. Has the function of transmitting to The serving base station has an output control processing function of individually increasing or decreasing the transmission signal power for each terminal station based on the increase / decrease request. That is, for a terminal station that has returned a signal indicating a request to increase the transmission signal power (or a signal indicating a decrease in communication quality), the transmission signal power for the signal transmitted to the terminal station is increased. The control is performed, and an operation is performed to maintain the communication quality at an appropriate level as much as possible. For example, when the communication quality of a specific terminal station is reduced due to local rainfall, control is performed to increase the transmission signal power of a signal to be transmitted to the terminal station based on an increase request from the terminal station. Therefore, a decrease in communication quality can be suppressed. Conversely, a signal indicating a request for reduction in transmission signal power (or a signal indicating improvement in communication quality) is sent back from a terminal station whose communication quality has been improved, and transmission of a signal to be transmitted to the terminal station is to be performed. Control for reducing the signal power is performed. Such control is repeatedly performed at a predetermined control cycle.

[0004]

As described above, a base station used in a general CDMA system performs output control processing for individually increasing or decreasing transmission signal power based on an increase or decrease request from each terminal station. In a predetermined control cycle. However, the sum of signal power transmitted from one base station to each terminal station cannot be increased indefinitely. The transmission equipment provided in the base station has a predetermined rated power as a matter of course, and cannot transmit a signal exceeding the rated power. Therefore, when a large number of terminal stations issue an increase request at the same time, as a base station,
In some cases, it is not possible to meet all of these increase requests.

[0005] Of course, it is also possible to adopt a method in which the transmission signal rated power of the base station is set as high as possible in advance, but this time, interference with a transmission signal from another adjacent base station is required. Another problem arises. Usually, a service coverage area is divided into a plurality of zones. Then, in each zone, multiple access is performed between one base station and a plurality of terminal stations.
In this case, if the service is provided independently for each zone, no problem occurs. However, as long as the signal is transmitted by radio, interference beyond the boundary of the zone must occur. In particular, a terminal station located at a zone boundary is affected by a transmission signal from another adjacent zone. Under such circumstances, a predetermined maximum value is set for the signal power that can be transmitted from one base station.

[0006] Therefore, when the transmission power is supplied to each terminal station according to the increase / decrease request, if the total transmission power exceeds the maximum value, the base station responds 100% to the increase request. You will not be able to do it. For this reason, conventionally, transmission signal power control is performed so as to respond only to a certain ratio of the increase request. However, the power increase request from the terminal station requires additional power necessary to maintain a constant communication quality in consideration of the communication quality at that time. If not, communication may be interrupted.

[0007] Therefore, the present invention provides a radio digital communication system capable of reducing the occurrence rate of communication interruption as much as possible even when there is a request to increase or decrease the total transmission power from a base station so as to exceed a predetermined maximum value. The purpose is to provide a method of providing services.

[0008]

(1) According to a first aspect of the present invention, a base station and a plurality of terminal stations are provided in a service providing area, and the base station and the plurality of terminal stations are provided between the base station and the plurality of terminal stations. In a method of providing a wireless digital communication service in which multiple access is performed using a method of simultaneously sharing the same frequency band, each terminal station may receive transmission with power suitable for maintaining predetermined communication quality. A function of transmitting a request for increase / decrease in transmission signal power addressed to itself to the base station is provided so that each base station can send / receive a request to each terminal station based on the request for increase / decrease transmitted from each terminal station. By providing a function to perform output control processing for individually increasing or decreasing transmission signal power at a predetermined control cycle, and performing output control processing as requested by the increase or decrease,
The sum of transmission signal powers for all terminal stations is a predetermined maximum value M
If the number exceeds the threshold, each terminal station is selected based on predetermined conditions into a licensing station that grants an increase / decrease request and a non-repudiation station that rejects the increase / decrease request. The rejection station does not perform control according to the increase / decrease request.

(2) The second aspect of the present invention is the above-mentioned first aspect.
In the method for providing a wireless digital communication service according to the aspect, a selection order indicating a priority to be selected as a non-repudiation station for each terminal station based on a predetermined rule is determined, and a licensing station is determined based on the selection order. Or a non-approval station.

(3) A third aspect of the present invention is the above-mentioned second aspect.
In the method for providing a wireless digital communication service according to the aspect, the transmission signal power for all the terminal stations whose selection order is within the j-th order is set to 0, and the transmission signal When the power is set to the power required for the increase / decrease, a minimum integer j such that the sum of the transmission signal powers is equal to or less than the maximum value M is obtained, and the terminal station whose sorting order is within the j-th rank is determined as a non-repudiation station. , The terminal station whose sorting order is the (j + 1) th or higher is set as the license station.

(4) The fourth aspect of the present invention is the above-described third aspect.
In the method for providing a wireless digital communication service according to the aspect, the transmission signal power to the non-repudiation station having the j-th sorting order is determined by the remaining power corresponding to the difference between the sum of the transmission signal powers to all the permission stations and the maximum value M And the sorting order is (j-1)
The transmission signal power for the non-repudiation stations within the order is set to 0.

(5) The fifth aspect of the present invention is the above-mentioned second aspect.
In the wireless digital communication service providing method according to the fourth to fourth aspects, the sorting order is determined according to the magnitude of the transmission signal power after the increase / decrease request.

(6) The sixth aspect of the present invention is the above-mentioned second aspect.
In the wireless digital communication service providing method according to the fourth to fourth aspects, the sorting order is determined based on a communication service providing fee for each terminal station.

(7) A seventh aspect of the present invention is the above-mentioned first aspect.
In the method for providing a wireless digital communication service according to the sixth to sixth aspects, as a communication method between the base station and the terminal station,
Code Division Multiple Access (CDMA: Code Division)
Multiple Access).

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments.

§1. First, the principle of a wireless digital communication service based on a general CDMA scheme will be briefly described. For example, when an area shown by a circle in FIG. 1 is given as a service providing area, the service providing area is divided into a plurality of zones. Here, for convenience of explanation, it is assumed that the zone is divided into three zones α, β, and γ as shown in the figure. Thus, when three zones are defined, a base station in charge is installed for each zone. In the illustrated example, a symbol indicated by a double circle indicates each assigned base station. That is, the assigned base station A is installed in the zone α, the assigned base station B is installed in the zone β, and the assigned base station C is installed in the zone γ. Each zone has a large number of users who receive services, and a terminal station is set up under each user. In the illustrated example, a symbol indicated by a single circle indicates each terminal station (here, for convenience of explanation, only a small number of terminal stations are shown, but in reality, a larger number of terminal stations are installed. For example, terminal stations a1 to a6 are installed in zone α. These terminal stations may be fixed terminals or mobile terminals.

In such a configuration, the provision of the wireless digital communication service is performed independently for each zone. That is, multiple access is made between one base station and a plurality of terminal stations existing in the zone in which the base station is in charge. For example, the terminal stations a1 to a6 in the zone α are all connected to the base station A in charge, and can receive a predetermined communication service by communicating with the base station A. Similarly, the terminal stations b1 to b5 in the zone β are all connected to the serving base station B, and the terminal stations c1 to c5 in the zone γ
Each of c5 is connected to the serving base station C.

As described above, as a system for performing multiple access connecting one base station and a large number of terminal stations, a frequency band is divided and used for each terminal station, or a communication time is individually used. There is also a scheme in which each terminal station is divided and used, but as described above, recently, a CDMA scheme that can simultaneously share the same frequency band is becoming mainstream. FIG. 2 is a graph showing resource utilization in the CDMA system. As shown, the resources are effectively used without being divided in both frequency and time. For example, in the diagram shown in FIG. 1, when the base station A is connected to all the terminal stations a1 to a6, the transmission signal of the base station A includes the signals for all the terminal stations a1 to a6 over the entire time zone. Is included, and
Signals for all terminal stations a1 to a6 are included over all frequency bands.

Such multiple access is made possible by performing encoding using a pseudo noise code unique to each user. By decoding the encoded transmission signal, the signal for each user can be separated again. FIG. 3 is a signal waveform diagram showing the principle of encoding using such a pseudo-noise code. For example, information represented by a digital signal S (a1) is transmitted to the terminal station a1, and a digital signal S (a) is transmitted to the terminal station a2.
Let us consider the case of transmitting the information shown in 2). In such a case, first, a pseudo noise code P (a1) is defined for the signal S (a1), and a pseudo noise code P (a2) is defined for the signal S (a2). These pseudo noise codes are unique digital noise signals whose frequencies are sufficiently higher than the signals S (a1) and S (a2) to be transmitted.
Each has a unique waveform pattern. Here, the coded signal C (a1) is defined by taking the exclusive OR of the signal S (a1) and the signal P (a1), and the exclusive control of the signal S (a2) and the signal P (a2) is performed. The coded signal C (a2) is defined by taking the logical sum. Then, the coded signal C (a1) is D / A converted and the analog signal A
(A1) is obtained, and the coded signal C (a2) is D / A converted to obtain an analog signal A (a2). Further, after multiplying each of these analog signals by the power gains G (a1) and G (a2), the two signals are added in an analog manner to obtain an analog sum signal W. The signal corresponding to the sum signal W thus obtained is transmitted from the base station A.

When each of the terminal stations a1 and a2 receives the sum signal W, it converts the sum signal into a digital signal, and then performs a process of extracting only information having a correlation with a unique pseudo noise code. For example, the terminal station a1 can separate and extract the signal S (a1), which is the original transmission information, by extracting only information having a correlation with the pseudo noise code P (a1). Similarly, the terminal station a2 extracts only the information correlated with the pseudo-noise code P (a2), thereby obtaining the signal S as the original transmission information.
(A2) can be separated and taken out. In the CDMA system, based on such a principle, it is possible to transmit information to a plurality of terminal stations in the same zone while simultaneously sharing the same frequency band.

In the above, an example has been described in which information is simultaneously transmitted to the terminal stations a1 and a2. However, when information is simultaneously transmitted to all the terminal stations a1 to a6, the analog signal A (a1)
To A (a6) to power gains G (a1) to G (a6), respectively.
The sum signal W obtained by multiplying (a6) and adding these is transmitted.

Here, each terminal station has a function of transmitting a signal indicating a request to increase or decrease the transmission signal power to itself to the responsible base station based on the communication quality at the present time. In addition, as a signal indicating this increase / decrease request,
The signal itself indicating the communication quality at the present time may be transmitted. That is, in this specification, the "signal indicating increase / decrease request" sent from the terminal station to the base station is equivalent to the "signal indicating communication quality". Each base station receiving such a signal has a function of performing output control processing for individually increasing or decreasing the transmission signal power for each terminal station at a predetermined control cycle.

In the example shown in FIG. 3, the base station A
As shown in the lower part of FIG. 3, a predetermined power gain is applied to the analog signal A (a1) containing the information component to be transmitted to the terminal station a1 in order to perform multiple simultaneous access to the terminal station a1 and the terminal station a2. G (a1) is obtained by multiplying an analog signal A (a2) including an information component to be transmitted to the terminal station a2 by a predetermined power gain G (a2), and adding both signals in an analog manner. The sum signal W is transmitted. The terminal stations a1 and a2 that have received the transmission signal perform a process of returning information indicating the quality of the received signal to the base station A as an increase / decrease request signal. The base station A has terminal stations a1,
The increase / decrease request signal returned from a2 is monitored every predetermined control cycle (for example, every 1 ms), and based on this increase / decrease request signal (or when a communication quality signal is transmitted, the communication quality is monitored). The power gain G (a, based on the increase or decrease in power required to maintain the signal at proper quality).
1), output control for increasing or decreasing the value of G (a2) is performed.

For example, when the signal gain received at the terminal station a1 is reduced due to local rainfall or the like, the terminal station a1 issues a communication quality signal indicating a decrease in reception power (an increase in transmission power). (Corresponding to a request signal). In such a case, the base station A performs control to increase the power gain G (a1) so that the communication quality in the terminal station a1 is appropriately maintained. Such an output control process is repeatedly performed at a control cycle of, for example, every 1 ms. Therefore, even in the next control cycle after 1 ms, a communication quality signal indicating a decrease in reception power is still returned from the terminal station a1. Power gain G
Control for further increasing (a1) is performed, and such a process of increasing the power gain is repeatedly performed until a communication quality signal indicating an appropriate communication quality is returned. Further, when the local rain stops, a communication quality signal (corresponding to a transmission power reduction request signal) indicating that the received power is excessive is returned. In such a case, , And conversely, the power gain G (a1)
Will be controlled.

§2. Problems in the conventional system In principle, by performing the power gain increase / decrease processing for each terminal station as described above, appropriate output control should be possible, but as already described, Since the transmission power of each base station cannot be increased indefinitely, if the output control is performed according to the increase / decrease request from all the terminal stations, when the sum of the transmission powers exceeds a predetermined maximum value M, Cannot perform correct output control. For example, in the example shown in FIG.
When there is a sudden rainfall in the entire zone α where .about.a6 is installed and a communication quality signal (transmission power increase request signal) indicating a decrease in communication quality is returned from each terminal station, the output of the base station A is output. Since the sum of the power cannot exceed the maximum value M, it is not possible to sufficiently respond to the power increase request from each of the terminal stations a1 to a6.

Here, a specific example of such a situation will be described. The table of FIG. 4 shows various values for the six terminal stations a1 to a6 in the zone α which the base station A is in charge of. Here, it is assumed that the maximum transmission power of base station A is determined to be M = 300 (for convenience of explanation, the unit of power is omitted and treated as an unknown number). In this case, the total sum of the transmission powers of the base stations cannot exceed M = 300 no matter what kind of increase or decrease request is made from each terminal station.

Now, signal transmission is performed to each terminal station ai (i = 1 to 6) at the power Pi as described in the column of “current transmission power” in FIG. Let's say you were. In this example, specifically, the current transmission power P1 = 10 for the terminal station a1, the current transmission power P2 = 30 for the terminal station a2,..., The current transmission power P2 for the terminal station a6
6 = 100. In other words, the power gain G
(A1) = 10, G (a2) = 30,..., G (a6) =
The setting of 100 is performed in the base station A. In this case, since the sum of the power transmitted from the base station A is ΣPi = 260 (i = 1 to 6), it is within the maximum transmission power M (M = 300).

In this state, the "request for increase / decrease" in FIG.
Suppose that an increase / decrease request Di as described in the column is given. In this example, the increase / decrease request from the terminal station a1 is
Although D1 = + 10 and a slight increase request is made, the increase / decrease request from the terminal station a2 is D2 = 0, indicating that the current status is maintained. Further, the increase / decrease request from the terminal station a3 is D3 = −10, and a slight decrease request is made.

Assuming that the output control process is executed as requested based on such an increase / decrease request, each terminal station a1
The transmission power for .about.a6 is the power value described in the "temporary transmission power" column of FIG. 4, that is, Pi + Di. However, the sum of the “temporary transmission power” is Σ (Pi
+ Di) = 350, which exceeds the maximum transmission power M. In such a case, conventionally, only a certain percentage of the individual increase requests is accepted, and adjustment is performed so that the final sum of the transmission power does not exceed the maximum transmission power M. For example, in the case of the illustrated example, if only 50% of the increase request is accepted, the amount Δi described in the column of “actual increase / decrease amount” in FIG. 4 can be obtained. That is, for the terminal stations a1, a4, a5, and a6 requesting the increase with Di> 0, the actual increase / decrease amount Δi = Di × 50%, and the terminal station requesting the current state maintenance with Di = 0. a2 and Di
For the terminal station a3 requesting a decrease as <0, the actual increase / decrease amount Δi = Di is used as it is.

By performing such an adjustment, the sum of the actual increase / decrease amount becomes ΣΔi = + 40. Even if this is added to the sum of the current transmission power ΣPi = 260, the sum of the new transmission power becomes the maximum transmission power. M will fall within 300. Power value PPi described in the column of “actual transmission power” in FIG.
Is a new value of the transmission power obtained by PPi = Pi + Δi, and the total sum ΔPPi = 300.

As described above, an example of the conventional adjustment method when an increase / decrease request is made to exceed the maximum transmission power M as a whole has been described. By performing such an adjustment method, it is possible to temporarily suppress the transmission power from the base station to the maximum transmission power M or less, but in practice, there is a problem that the communication may be interrupted. Will happen. For example, in the example shown in FIG. 4, the terminal station a1 sends an increase / decrease request Di.
= + 10, which means that considering the current communication quality at the terminal station a1, it is necessary to increase the transmission power to the terminal station a1 by another 10 to 20 to maintain an appropriate communication quality. It cannot be done. However, the new transmission power PP1 for the terminal station a1 is set to 15. In this case, it suffices if the call quality is simply degraded, but if the rainfall at the next moment happens to further increase, the call may be interrupted.

It should be noted here that the danger of such a call interruption is not limited to the terminal station a1, but occurs in all terminal stations that have issued an increase request. That is, for the terminal station a4, only 40 where the power of 60 is originally required is supplied, and for the terminal station a5, only 100 where the power of 120 is originally required is supplied. For the terminal station a6, Since only 105 is supplied where 110 power is originally required, there is a danger of a call interruption at any of the terminal stations a1, a4, a5 and a6. In the worst case, a situation may occur in which the calls of all four terminal stations are interrupted.

§3. The method according to the present invention The basic idea of the present invention is that, even if the maximum transmission power is transmitted from the base station, if the increase request of all the terminal stations cannot be satisfied, the specific terminal station is intentionally sacrificed. In that other terminal stations are rescued. In other words, when the output control processing is performed according to the increase / decrease request from each terminal station, if a situation occurs in which the sum of the transmission signal powers for all the terminal stations exceeds the predetermined maximum value M, based on the predetermined condition, Then, each terminal station is classified into a license station that permits an increase / decrease request (a terminal station to be remedied) and a non-repudiation station (a terminal station that is a victim) that denies the increase / decrease request. Then, the power output control according to the increase / decrease request is performed for the licensing station, and the power output control according to the increase / decrease request is not performed for the non-approval station.

By performing such a process, at least the power supply at the licensing station is ensured as requested, so that a situation in which the call is interrupted can be avoided. On the other hand, since the power supply is not performed as requested in the non-repudiation station, there is a risk that the call will be interrupted. However, this is inevitably divided. In particular, the embodiment described below employs a method of intentionally interrupting a call by setting the transmission power to 0 and allocating surplus power generated by this to the licensing station. A terminal station selected as a consent station is more likely to be interrupted, but a terminal station selected as a licensed station is significantly less likely to be interrupted.

The basic concept of the present invention is that, as described above, when a situation occurs in which power cannot be supplied as requested as a whole, each terminal station becomes a licensing station and a denying station. There is a point that the licensing bureaus are sorted out and the bureaus are always rescued. However, in order to select the licensing bureaus from the banning bureaus, it is necessary to set some rules. This rule, for example, "ran random selection using random numbers"
However, in practice, a sorting order indicating the priority to be sorted as a non-repudiation station is determined, and based on this sorting order, whether to set the licensing station or the non-repudiation station is selected. Is preferably performed. Since the stations are selected as non-repudiation stations in the order of the higher selection order, this order can be called a priority to be sacrificed.

One method of determining the sorting order is to assign an absolute order to each terminal station in advance. Specifically, for example, a method that is determined based on the provision fee of the communication service for each terminal station may be adopted.
That is, if the sorting order is set in ascending order of the contract fee for each terminal station, a terminal station receiving a service with a lower contract fee has a higher possibility of being selected as a non-repudiation station, and call interruption is caused. The probability of occurrence is high. A contractor who receives a communication service using a terminal station makes a contract in a preferred sorting order in consideration of whether to emphasize communication stability or cost.

Another method of determining the sorting order is a method in which the absolute order is not defined for each terminal station, but is basically basically equal, and the sorting order is assigned at each time. . In this case, it is preferable to define a rational sorting order so that the number of non-repudiation stations can be reduced as much as possible. Specifically, it is reasonable to adopt a method of determining the sorting order according to the magnitude of the transmission signal power after the increase / decrease request. That is, in the case of the example shown in FIG. 4, the provisional transmission power (P is obtained by adding the increase / decrease request Di to the current transmission power Pi.
Focusing on the magnitude of (i + Di), the selection order is determined in the order of the magnitude of the temporary transmission power. In this example, since the provisional transmission power of the terminal station a5 is the largest (P5 + D5) = 120, the terminal station a5 is ranked first, and the terminal stations a6, a4, a2, a1, a3 and so on are ranked second and thereafter. Will continue. As described above, when employing a method of determining the sorting order according to the magnitude of the transmission signal power after the increase / decrease request, the transmission power for the terminal station selected as the non-repudiation station may be set to 0 for the time being. When the transmission power becomes 0, the communication is interrupted for this non-repudiation station. On the other hand, all of the transmission power requested by the non-approval station can be allocated to another license station. If the rejected stations are selected in the order of the magnitude of the transmission signal power after the increase / decrease request, it is reasonable that the signal power that can be allocated to other licensed stations becomes relatively large.

Hereinafter, a specific example of selecting a rejection station / licensing station and performing output power control based on such a policy will be described.
This will be described with reference to the charts of FIGS. These charts show various values regarding the six terminal stations a1 to a6 in the zone α assigned to the base station A, similarly to the chart shown in FIG. Again, it is assumed that the maximum transmission power for base station A is defined as M = 300.

Here, signal transmission is currently performed to the terminal station ai (i = 1 to 6) at the power Pi as described in the column of “current transmission power” in FIG. Assume that in this state, the communication quality signal returned from each of the terminal stations a1 to a6 gives an increase / decrease request Di as described in the column of “increase / decrease request” in FIG. In this case, assuming that the output control processing is performed as requested based on such an increase / decrease request, the transmission power to each of the terminal stations a1 to a6 is “temporary transmission power” in FIG.
, Ie, Pi + Di. However, the sum of the “temporary transmission power” is Σ (P
i + Di) = 350, which exceeds the maximum transmission power M. The numerical values up to this point are exactly the same as in the case of the conventional system shown in FIG. However, in the conventional method, as described in the column of “actual increase / decrease amount” in FIG.
An adjustment is made so as to accept only 50% of the increase request from each terminal station, and the total sum of the new transmission power is the maximum transmission power M = 3.
00.

In the method according to the embodiment of the present invention described here, at this point, the sorting order is determined for each terminal station. Here, it is assumed that the sorting order is determined based on the magnitude of the transmission signal power after the increase / decrease request (that is, the magnitude of the temporary transmission power (Pi + Di) shown in FIG. 5). The numerical value described in the column of “sorting order” in FIG. 5 indicates this sorting order. Specifically, the terminal station a5 having the temporary transmission power having the maximum value 120 becomes the first place. , The terminal station a in which the temporary transmission power indicates the minimum value 10
3 is the lowest (sixth).

Subsequently, a process of selecting each terminal station into a non-repudiation station and a permission station based on the selection order is performed. At this time, the condition α: the permission station is transmitted as requested. Signal power can be ensured (in other words, the sum of provisional transmission powers for the licensing stations should be less than or equal to the maximum transmission power M). Condition β: The number of non-repudiation stations should be as small as possible. It is most rational to perform a selection that satisfies the two conditions. Specifically, the screening may be performed according to the following policy. That is, the transmission signal power for all the terminal stations whose sorting order is within the j-th place is set to 0, and the transmission signal power for all the terminal stations whose sorting order is the (j + 1) -th place or later is set to the power according to the increase / decrease request. In this case, a minimum integer j such that the sum of the transmission signal powers is equal to or less than the maximum value M is obtained, the terminal stations whose sorting order is within the j-th place are rejected stations, and the sorting order is (j
The terminal stations after the (+1) th rank may be set as license stations.

If the total sum of the transmission signal powers for all the license stations does not reach the maximum value M when the selection is performed in this way, the power corresponding to the difference (remaining power) is determined by the selection order. May be assigned to the j-th non-repudiation station. In other words, the sorting order is (j-
1) Since the transmission signal power for the non-repudiation stations within the rank becomes 0, the communication is surely interrupted. However, among the non-repudiation stations, the j-th terminal station having the lowest selection order is Since the remaining power is supplied, there is a possibility that the communication will not be interrupted. If you do this,
It is possible to reduce the number of terminal stations in which communication is interrupted as much as possible while effectively using the power up to the maximum transmission power M.

Now, an output control process based on the above policy will be described with reference to a specific example shown in FIG. First, parameter j = 1 is set. This parameter j is a parameter indicating the number of non-repudiation stations, and as described above, must be a minimum integer (condition β) on condition that the condition α is satisfied. First, when j = 1 is set, only the terminal station a5 in the first place in the sorting order becomes a non-repudiation station, and all the remaining terminal stations become permission stations. Therefore, when it is checked whether the condition α is satisfied by such a selection, the total sum of the provisional transmission powers of the five license stations a1, a2, a3, a4, and a6 is 230, which is equal to or less than the maximum transmission power M. And the condition α is satisfied. Therefore, the parameter j = 1 is a parameter value that satisfies the condition, and the selection is performed with only the terminal station a5 having the first selection rank as the non-approval station and the other terminal stations as the permission stations.
“Allow” and “No” described in the column of “selection result” in FIG. 5 indicate the selection result of each terminal station.

After the selection is performed in this manner, the license station may supply the requested transmission power as it is. Numerical value P described in the column of "actual transmission power" in FIG.
Pi is the transmission power value actually supplied to each terminal station after the output control processing. For the license authority, PPi = Pi +
Di (temporary transmission power). On the other hand, the actual transmission power PPi of the rejecting station is basically set to 0. However, if there is remaining power (power still remaining before reaching the maximum transmission power M), the remaining power is reduced to zero. The sorting order is assigned to the j-th rejecting station (the rejecting station with the lowest sorting order). In the case of the example of FIG. 5, since the non-repudiation station is only the terminal station a5, the remaining power 70 is allocated to this terminal station a5. Thus, the sum of the actual transmission powers ΣPPi
Becomes equal to the maximum transmission power M = 300.

If such output power control is performed, in the next control cycle, at least the license station is supplied with the required transmission power, and controls as usual (control not restricted by the maximum transmission power M). Will be performed. On the other hand, the refusal station will not supply the transmission power as requested based on the determination that the communication interruption is unavoidable, but the remaining power will be allocated, resulting in the communication interruption. There is no possibility.

FIG. 6 is a chart showing the state of each terminal station in the next control cycle in which the output power control shown in FIG. 5 is executed. That is, at the current time, signal transmission is performed to the terminal station ai (i = 1 to 6) at the power Pi as described in the column of “current transmission power” in FIG. The current transmission power Pi shown in FIG. 6 is equal to the actual transmission power PPi shown in FIG. For example, if one control cycle is 1
When set to msec, output control for adjusting the value of transmission power for each terminal station is performed every 1 msec, and between the state shown in FIG. 5 and the state shown in FIG. There will be a time difference. That is, when the actual transmission power PPi as shown in FIG. 5 is determined, adjustment is performed to make the actual transmission power PPi a new transmission power, and each terminal station sets the new transmission power as the current transmission power. A request to increase or decrease the case will be returned.

Here, it is assumed that an increase / decrease request Di as described in the column of “increase / decrease request” in FIG. 6 is given.
In the illustrated example, the terminal station a2 indicates a large increase request of +90. This indicates that the communication quality at the terminal station a2 has dropped sharply, and such a situation has actually occurred, for example, because a construction crane installed near the terminal station a2 has moved. It can happen. As a result, the total increase / decrease request Di from each terminal station is:
ΣDi = + 180. However, since the total transmission power from the base station A has already reached the maximum transmission power M = 300 at this point in time, assuming that a further increase request has been accepted, the transmission power for each of the terminal stations a1 to a6 is as shown in FIG. Power value Pi + Di described in the column of “temporary transmission power”
And the sum is 和 (Pi + Di) = 480. In this case, the maximum transmission power M will greatly exceed 300.

Therefore, at this point again, the sorting order is determined for each terminal station. Here, similarly to the example of FIG. 5, the order of the magnitude of the transmission signal power after the increase / decrease request (that is,
(The order of the values of the provisional transmission power (Pi + Di) shown in FIG. 6)
When the sorting order is determined on the basis of the “selecting order” in FIG.
The sorting order according to the numerical value described in the column is obtained.
Unlike the case of FIG. 5, this time, the provisional transmission power has the maximum value 1
The terminal station a6 indicating 40 is the first place, and the terminal stations a1 and a3 having the minimum temporary transmission power value 30 are the lowest places (both are the fifth places).

Subsequently, a process of selecting each terminal station into a rejecting station and a licensing station based on the sorting order is performed. At this time, as described above, the conditions α and β are satisfied. Such sorting is performed. First, assuming that the parameter j = 1 is set and only the terminal station a6 in the first place in the sorting order is the non-repudiation station, the remaining five permission stations a1, a2, a3, a4, a5
Is 340, still exceeds the maximum transmission power M = 300, and the condition α is not satisfied. Accordingly, if the parameter j = 2 is increased and the terminal station a6 having the first ranking in the sorting order and the terminal station a2 having the second ranking in the sorting order are rejected stations, the remaining four licensed stations a
The sum of the provisional transmission powers for 1, a3, a4, and a5 is 2
The maximum transmission power is M = 300 or less. As a result, the condition α is satisfied by the setting of the parameter j = 2. Therefore, the selection is performed with the terminal stations a5 and a2 having the second or lower ranking in the rejection station and the remaining terminal stations as the permission stations. “Allow” and “No” described in the column of “selection result” in FIG. 6 indicate the selection result of each terminal station.

After the selection is performed in this manner, the license authority may supply the requested transmission power as it is. Numerical value P described in the column of "actual transmission power" in FIG.
Pi is the transmission power value actually supplied to each terminal station after the output control processing. For the license authority, PPi = Pi +
Di (temporary transmission power). On the other hand, the actual transmission power PPi of the non-repudiation station is basically set to 0, but if there is remaining power, the remaining power is determined by the non-repudiation station having the j-th sorting order, that is, In the case of the example, it is assigned to the second-ranking non-approval station a2. Eventually, the actual transmission power for the non-repudiation station a6 is PP6 = 0, and the communication interruption is inevitable.
Since the remaining power 80 is allocated, the remaining power 80 does not reach the tentative transmission power 120 which is the original request, but there is a possibility that communication interruption is avoided. Thus, the sum of the actual transmission power ΣP
Pi is again equal to the maximum transmission power M = 300.

FIG. 7 is a flowchart showing a procedure of the above-described output power control. First, in step S1, the current transmission power Pi for each terminal station and the increase / decrease request Di returned from each terminal station are recognized, and in the following step S2, each temporary transmission power (Pi + Di) is calculated. Then, in step S3, the magnitude relationship between the calculated total sum 仮 (Pi + Di) of the tentative transmission power and the maximum transmission power M is compared. If Σ (Pi + Di) is less than or equal to M, the process proceeds to step S4. , All terminal stations are licensed stations. In this case, transmission power is supplied to all terminal stations as requested.

On the other hand, in step S3, Σ (Pi +
If Di) exceeds M, it becomes impossible to supply transmission power as requested to all terminal stations, and thus, in step S5, a sorting order is determined first.
In the above example, the provisional transmission power (P
The order of the magnitude of (i + Di) is determined as the sorting order.
Then, in a step S6, the parameter j is set to an initial value 1, and in a step S7, the sorting order (j +
1) The sum Sj of the temporary transmission powers after the order is calculated. This is an operation for obtaining the sum of the temporary transmission powers of the licensing stations (the terminal stations of the (j + 1) th and higher sorting orders), assuming that the terminal stations whose sorting order is up to jth are non-repudiating stations. Will be. Then, in step S8, the magnitude relationship between Sj and M is compared. If Sj is equal to or less than M, the process proceeds to step S10. If Sj still exceeds M, the number of non-repudiation stations is increased. Since it is necessary to further increase, in step S9, j is increased by 1 (the number of non-repudiation stations is increased by 1), and the calculation in step S7 is performed again. This procedure corresponds to a procedure for finding the minimum j that satisfies the condition α described above.

When the minimum value of the parameter j that satisfies the condition α is determined in this way, in step S10, the terminal stations up to the j-th sorting order are rejected stations and the terminal of the sorting order (j +
1) The terminal stations after the rank are officially selected as license stations. In the following step S11, a process of setting the actual transmission power PPi of each licensing station to the provisional transmission power (Pi + Di) is performed, and the required transmission power is secured for each licensing station. Next, in step S12, the actual transmission power for each non-repudiation station is set.
The actual transmission power PPi of the non-repudiation station is basically set to 0, but the setting of the actual transmission power PPj = remaining power is made for the non-repudiation station of the j-th sorting order.

As described above, the processing of steps S1 to S12 is a control processing performed in one control cycle. With this control processing, a new transmission power for each terminal station is determined, and the actual transmission power is updated. You. Thus, the processing from step S1 is repeatedly executed again.

Although the method for providing a wireless digital communication service according to the present invention has been described based on the illustrated embodiment, the present invention is not limited to this embodiment.
The present invention can be implemented in various other modes. For example, in the above embodiment, the tentative transmission power (P
Although the sorting order is determined based on the magnitude of (i + Di), the sorting order can be determined based on, for example, the magnitude of the current transmission power Pi, or the increase / decrease request Di.
Can also be determined based on the size of. other than this,
The sorting order can be determined according to the contract amount, or the definition of the sorting order can be changed depending on the time zone. In the above embodiment, the increase / decrease request Di
Is given as the absolute value of the power, and the provisional transmission power is determined by adding the increase / decrease request Di to the current transmission power Pi. However, the increase / decrease request is given by a magnification (for example, a decibel value),
The provisional transmission power may be determined by multiplying the current transmission power by the increase / decrease supply. Further, in the above-described embodiment, the output control process is performed at a constant period of 1 msec. However, the control period does not necessarily have to be a constant period, and the individual periods may be different as long as they are repeatedly executed. .

[0056]

As described above, according to the wireless digital communication service providing method of the present invention, when it is not possible to sufficiently respond to an increase request from each terminal station, each terminal station is rejected as a license station. Because we sifted to the stations, we decided to supply only the licensed stations with the transmission power as requested by the increase,
Even when there is a request to increase or decrease the total transmission power from the base station so as to exceed a predetermined maximum value, it is possible to reduce the occurrence rate of communication interruption as much as possible.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating the principle of a wireless digital communication service based on a general CDMA system.

FIG. 2 is a graph showing a resource use mode in a general CDMA system.

FIG. 3 is a signal waveform diagram showing a principle of encoding using a pseudo-noise code used in a general CDMA system.

FIG. 4 is a table showing a specific example of transmission output control according to a conventional method.

FIG. 5 is a chart showing a specific example of transmission output control by a method according to the present invention.

FIG. 6 is a chart showing another specific example of transmission power control by the method according to the present invention.

FIG. 7 is a flowchart illustrating an example of a transmission output control procedure according to the present invention.

[Explanation of symbols]

 A, B, C ... base stations a1 to a6, b1 to b5, c1 to c5 ... terminal stations A (a1), A (a2) ... transmission analog signals C (a1), C (a2) ... coded signals Di ... Increase / decrease request G (a1), G (a2): power gain M: maximum transmission power Pi: current transmission power PPi: actual transmission power (new transmission power) S (a1), S (a2): original transmission information W ... Sum signal α, β, γ ... Zone Δi ... Actual increase / decrease amount

Claims (7)

[Claims] A base station and a plurality of terminal stations are provided in a service providing area, and multiple access is performed between the base station and the plurality of terminal stations by using a method of simultaneously sharing the same frequency band. In the wireless digital communication service providing method, each terminal station issues a request to increase or decrease the transmission signal power destined for itself so that the terminal station can receive transmission with power suitable for maintaining a predetermined communication quality. A function of transmitting to a base station is provided.Each base station performs output control processing for individually increasing or decreasing transmission signal power to each terminal station based on an increase / decrease request transmitted from each terminal station. A function to be performed in a control cycle is provided, and when the output control processing is performed according to the increase / decrease request, if the sum of transmission signal powers for all terminal stations exceeds a predetermined maximum value M, each terminal is controlled based on predetermined conditions. Station Selection is made between a license bureau that grants the increase / decrease request and a refusal bureau that denies the increase / decrease request. The license bureau performs control as requested by the increase / decrease request, and does not control the refused station according to the change request. A method for providing a wireless digital communication service. 2. The method for providing a wireless digital communication service according to claim 1, wherein a selection order indicating a priority to be selected as a non-repudiation station is determined for each terminal station based on a predetermined rule. A method for providing a wireless digital communication service, comprising: selecting whether to be a licensed station or a non-approved station based on the order. 3. The method of providing a wireless digital communication service according to claim 2, wherein the transmission signal powers for all the terminal stations whose sorting order is within the j-th place are 0, and the sorting order is (j + 1) -th and higher. When the transmission signal power for all the terminal stations is set to the power required for the increase / decrease request, a minimum integer j such that the sum of the transmission signal powers is equal to or less than the maximum value M is obtained. The terminal station is regarded as a non-repudiation station, and the sorting order is (j +
1) A method of providing a wireless digital communication service, wherein a terminal station after the first place is a license station. 4. The method of providing a wireless digital communication service according to claim 3, wherein a transmission signal power for a non-repudiation station having a j-th sorting order is a sum of a transmission signal power for all licensing stations and a maximum value M. And a transmission signal power for a non-repudiation station whose sorting order is within the (j-1) th rank is set to 0, the method for providing a wireless digital communication service. 5. The wireless digital communication service providing method according to claim 2, wherein the selection order is determined according to the magnitude of the transmission signal power after the increase / decrease request. How the service is provided. 6. The wireless digital communication service providing method according to claim 2, wherein the selection order is determined based on a communication service providing fee for each terminal station. How to provide communication services. 7. The method for providing a wireless digital communication service according to claim 1, wherein a code division multiple access method is used as a communication method between the base station and the terminal station. A method for providing a wireless digital communication service.