Method and device for transmission power adjustment in digital mobile radio system

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention generally relates to transmission power control in cellular radio systems, and more particularly to methods and devices for adjusting the power of signals transmitted by cellular radio transmitters.

【0002】

[Conventional technology]

The cellular mobile radio system includes a plurality of cells. Each cell has at least one base station for communicating with several mobile stations at the same time. Signal transmission is performed by transmitting and receiving radio signals between a base station in a cell and a mobile station serviced by that base station, for example when the mobile station is used for the purpose of making a call. Is done.

【0003】

Efficient use of the same communication path is a large cellular cell such as a system using frequency division multiple access (FDMA) technology or time division multiple access (TDMA) technology. It is especially important in the design of wireless systems. However, in an environment with a large number of cells, common channel interference caused by the use of the same frequency is the only major limiting factor for system capacity. In particular, the attenuation suffered by the signal being transmitted over long distances is insufficient to insulate each cell from each other. One method of increasing interest in curbing common line interference is to use transmit power control. The basic idea is to adjust the transmission power in each base station / mobile station link so that the interference level at other reception points is minimized.

【0004】

However, there are strict restrictions on maintaining sufficient transmission quality on communication links. For example, if a signal transmitted by a mobile station arrives at the base station receiver at an extremely low power level, the bit error rate is too high to enable high quality communication. However, if a signal transmitted by a particular mobile station arrives at the base station receiver at an extremely high power level, it is transmitted by another mobile station that shares the same communication path with that high power. Interference with the signal is caused. Therefore, if the transmission power of each mobile station receives an incoming call to the base station with the minimum signal-to-noise interference ratio that can satisfactorily recover the data, the system capacity is maximized.

【0005】

Early studies on transmit power control found that a good measure of quality in cellular system design is the carrier-to-interference ratio (CIR). The idea of CIR harmony in the context of satellite systems is described in JM Aein's paper "Power Balancing in Systems Employing Frequency Reuse", COMSAT Tech. Rev., vol. 3, No. 2, pp. 277-300 (1973). Introduced inside. This article and other publications referred to herein are used as references for the practice of the art. This transmission power balancing method aims to obtain the same CIR for all communication links. Another paper by RW Nettleton and H. Alavi, "Power Control for Spread-spectrum Cellular Mobile Radio Systems", Proc. IEEE Vehic. Tech. Conf., VTC-83, pp. In 242-246 (1983), this concept of transmit power balancing is used in the context of cellular radio systems.

【0006】

Recent research has emphasized distributed control, that is, local control. In some distributed generation control systems, the power level of each transmitter is controlled using only local measurements, resulting in all receivers eventually meeting predetermined CIR requirements. Distributed generation control is of particular interest because the alternative centralized power controller is accompanied by further weakening of infrastructure and network.

【0007】

Mathematical analysis in the field of distributed generation control follows two different paths. The first is about maximizing the minimum CIR. For example, in J. Zander's paper, "Performance of Optimum Transmitter Power Control in Cellular Radio Systems", IEEE Trans. Vehic. Tech., Vol. 41, No. 1, pp.57-62 (1992), at the receiver. Iterative techniques have been disclosed that act in the absence of noise so that the signals of a particular number of users together generate signal power that can achieve maximum CIR. However, this method ignores noise such as noise at the receiver, thermal noise, and external noise, and the vectors of each transmission power converge within a certain ratio.

【0008】

The second approach is to recognize the presence of noise and require that the CIR of all links not be less than a pre-determined goal determined by considering quality of service. There are some that set the conditions to be used. For example, GJ Foschini's paper "A Simple Distributed Autonomous Power Control Aigorithm and Its Convergence", IEEE Trans. Vehic. Tech., Vol. 42, No. 4, pp. 642-646 (1993) states that all users Synchronous algorithms are presented that are performed simultaneously in an iterative manner in order to reset each power level to the level required for each to have good performance. Thus, each user can continue voluntarily as if no other user had attempted to change their power level. The distributed synchronization algorithm converges exponentially.

【0009】

One requirement of the model discussed in the Foschini paper above is that there is simultaneity among different users. However, the need for simultaneity increases the cost of transmitting power control in cellular radio systems. In order to achieve simultaneity, it is necessary to use an expensive clock device or timing device. Otherwise, inexpensive clock devices can be used with feedback forms such as phase-locked loops to achieve synchronization functionality. In either case, the cost of obtaining transmit power control increases as the degree of simultaneity increases.

【0010】

Systems have been proposed that include methods for performing transmit power control in cellular radio systems. U.S. Pat. No. 5,267.262 states code division multiple access. A power control system for a cellular mobile phone system using access; CDMA) technology is disclosed. The system includes means for controlling transmission power transmitted by a particular mobile station and received by a particular base station communicating with that mobile station. The power of the signal transmitted by the mobile station is measured when it is received by the specific base station. The measured signal strength is compared to the desired signal strength level for the particular mobile station. A transmission power adjustment command is generated and transmitted to that mobile station. In response to the transmission power adjustment command transmitted from the specific base station, the mobile station increases or decreases the transmission power of the mobile station by a certain predetermined amount of less than 1 dB. However, communication paths are not used in systems that use CDMA. Therefore, although it is important to use transmit power control to reconcile the goal of high system capacity with the goal of high transmission quality, the idea of efficiently using the same communication path uses CDMA technology. Not suitable for systems that do.

【0011】

U.S. Pat. No. 5,241.690 also discloses a method for adjusting transmit power in a digital mobile telephone system. In that method, the output power of the mobile station or base station is adjusted to maintain its transmission power at an optimum value. Signal strength and transmission quality measurements are collected and their average is calculated. Predicted signal strength and transmission quality are calculated later. The transmitted power at a later point in time is adjusted based on those predictions. The transmission power is increased when the predicted transmission quality is less than the desired transmission quality and reduced when the predicted transmission quality is higher than the highest permissible quality or the predicted signal strength is greater than the maximum permissible value.

【0012】

[Problems to be Solved by the Invention]

The present invention relates to a signal transmitted from a plurality of cellular radio transmitters in a digital mobile radio system, each of which communicates via the same digital radio communication path as the corresponding cellular radio receiver. It is an object of the present invention to provide a method and an apparatus for adjusting power.

【0013】

[Means for solving problems]

The method of the present invention includes a step of executing an update routine for each of the plurality of cellular radio transmitters, and a step of executing the update routine for each of the plurality of cellular radio transmitters among the plurality of cellular radio transmitters. It consists of steps that are iteratively performed in a way that does not require simultaneity or coordination between the two. The update routine includes the step of calculating the signal path gain between the transmitter and its corresponding receiving station and the step of measuring the common communication path interference power level at the corresponding receiving station. The update routine also multiplies the signal path gain, the common channel interference power level, and the pre-determined value corresponding to the minimum target value of the ratio of the received carrier power to the common channel interference power. Includes steps to calculate. The update routine further includes adjusting the power of the signal transmitted by the transmitter according to the product.

【0014】

[Action]

Alleviating the need for simultaneity and coordination between multiple transmitters, the signal power was determined in advance by the ratio of carrier power to common line interference power, at least derived from quality of service considerations. It converges at a geometric series pace to the optimum transmit power, which is defined as the minimum power required to maintain the same magnitude as the target value.

【0015】

[Example]

FIG. 1 shows an example of a cellular mobile radio system for which the method of the present invention is particularly useful. FIG. 1 illustrates seven cells C1 to C7, each of which has a corresponding base station 10 to 16. The cellular mobile radio system 1 of FIG. 1 also includes five mobile stations 20-24, each of which is not only mobile within one cell, but also from one cell to another. It is also possible to move to the cell. These mobile stations 20 to 24 are, for example, portable cellular telephones. Although the cellular mobile radio system 1 in FIG. 1 shows only 7 base stations and 5 mobile stations, there are typically tens of thousands of cellular systems such as the cellular mobile radio system 1. You can have hundreds of base stations servicing your mobile phone.

【0016】

The cellular mobile radio system 1 also includes at least one dual radio communication path shared by all base stations 10 to 16 and mobile stations 20 to 24. In order to actually realize the dual wireless communication path, for example, frequency division multiple access (FDMA) technology or time division multiple access (TDMA) technology can be used. This dual wireless communication path can allow telephone conversations in both directions at the same time. This dual radio line typically uses one frequency band for transmission to the outgoing link, i.e., transmitting from the transmitter at the base station to the receiver at the mobile station, and transmitting to the incoming link. That is, it is provided by using a different frequency band for transmission from the transmitter at the mobile station to the receiver at the base station.

【0017】

The cellular mobile radio system 1 of FIG. 1 also includes a system controller 30. The system controller 30 is connected to the base stations 10 to 16 by an appropriate communication medium such as a dedicated telephone line, an optical fiber link, or a radio frequency communication means. For clarity of explanation, only one wire 40 is shown connecting the system controller 30 to base station 11. However, it can be seen that similar connections exist between the system controller 30 and other base stations 10 and base stations 12-16. The system controller 30 controls the route selection of a call from the public switched telephone network to the appropriate mobile station for transmission to the appropriate mobile station. The system controller 30 also controls the routing of calls made from those mobile stations to the public switched telephone network via at least one base station.

【0018】

Many digital cellular mobile radio systems are well known in the art. Similarly, base stations and mobile stations for use in digital mobile radio systems are also well known in the art. However, if you are not familiar with this technology, please refer to EIA / TIA, Cellular System, Dual-Mode Mobile Station-Base Station Compatibility Standard, IS-54 for reference information on digital mobile radio stations using TDMA. Can be done.

【0019】

The present invention relates to a method of controlling or adjusting the power of a signal transmitted between a mobile station and a base station so that the power level is maintained at an optimum level as defined below. The goal of the general properties of the present invention is to keep the carrier-to-interference ratio (CIR) of each link at least as large as some pre-determined target value ρ obtained from quality of service considerations. However, the goal is to minimize the transmission power of those transmitters. Here, the CIR is defined as the carrier power received at a specific base station or mobile station divided by the total common communication path interference power (CCIP) at that base station or mobile station. The minimum transmission power that satisfies the above characteristic target is the optimum power level to be transmitted by the transmitter.

【0020】

In the following discussion, the above incoming link will be considered. However, it goes without saying that this consideration is merely an example, and the method of the present invention can be applied to the outgoing link as well.

【0021】

Therefore, in the following discussion, a mobile station such as mobile station 20 can be called a transmitting device, and a base station such as base station 11 can be called a receiving station. It goes without saying that the mobile station and the base station can both be reversed, and both serve as either a transmitting device or a receiving station. Further, for the sake of explanation, each of the mobile stations 20 to 24 in FIG. 1 has a time point t.₀Is assumed to be communicating with another base station among the base stations 10 to 16 on the same communication path. For example, mobile station 20 is communicating with base station 11. Similarly, mobile stations 21, 22, 23 and 24 each communicate with base stations 13, 15, 16 and 14, respectively. Time point t₀So, the mobile station 20 has the base station 11 and the average power P (t).₀) Is communicating. The carrier power C received from the mobile station 20 at the base station 11 is C = G × P (t).₀) Can be written. Note that G is the arrival signal path gain of the link between the mobile station 20 and the base station 11.

【0022】

FIG. 2 is a flow chart showing each step of an update routine for adjusting the transmit power of a mobile station or other transmitter according to the method of the invention. A mobile station whose transmission power should or is adjusted is referred to as an updated mobile station in the following discussion. According to the method of the present invention, the arrival signal path gain G between the updated mobile station, for example, the mobile station 20, and the base station with which the mobile station 20 is communicating, in this example, the base station 11, is step 210. It is calculated by. As shown in step 220, the co-channel interference power lever (CCIP) at base station 11 is also measured or calculated.

【0023】

Next, as shown in step 230, the pre-determined target value (ρ) of the CIR, the reciprocal of the calculated signal path gain (1 / G), and the measured common communication path interference. The product of power (CCIP) is calculated. The product obtained as a result is the power level to be set for transmission at the mobile station 20. As a result, in step 240, the power of the signal transmitted by the mobile station 20 is updated to the value calculated in the previous step 230. Thus at the time t₀As a result of the transmission power adjustment at, at that time t₀Later, the transmission power of mobile station 20 is updated. As a result of updating the transmission power of the mobile station, the transmission power of the mobile station is increased or decreased, or there is no change. The update routine shown in FIG. 2 is iteratively executed for the mobile station 20 without imposing the need for simultaneity as described below.

【0024】

The cycle of steps 210-240 is similarly repeated for each of the other mobile stations 21-24. This transmit power update routine is performed for each mobile station or transmitter without imposing the need for simultaneity and coordination between the various mobile stations or transmitters, as further described below.

【0025】

FIG. 3 is a diagram showing a situation in which all of the mobile stations 20 to 24 simultaneously update their transmission powers in parallel, that is, a situation in which there is simultaneity, and the time interval between each continuous transmission power update cycle is Equivalent. In FIGS. 4, 5, 6 and 7, the "x" mark indicates the time when the transmit power of a particular transmitter is updated or adjusted.

【0026】

Some mitigations can be made to the need for simultaneity and coordination shown in Figure 3. One such mitigation requires that the time interval between each successive transmit power update cycle, i.e., the time interval between each consecutive cycle of the update routine, remain constant. It can be done by removing the condition. This situation is shown in the graph of FIG. 4, and as shown in the figure, the time interval between each continuous transmission power update cycle is changing. While the mobile stations 20 to 24 continuously update their transmission powers in cooperation with each other, the time interval between each consecutive transmission power update cycle need not remain the same.

【0027】

Another mitigation can be achieved by removing the condition that requires all of the mobile stations 20 to 24 to update their transmission powers in parallel at the same time, as shown in the graph of FIG. .. Each of the mobile stations 20 to 24 updates its transmission power at the same constant pace as the other mobile stations, but in practice the transmission power update cycle of one mobile station and at least one other mobile station. There is a phase delay with the transmit power update cycle. Further, the phase delay between mobile stations 20 to 24 may be different.

【0028】

Yet another mitigation is that all of the mobile stations 20-24 require their transmit power to be updated at the same pace, i.e. the iterative execution of the update routine is for all of the mobile stations 20-24. On the other hand, it can be done by removing the conditions that require it to be done at the same pace. This situation is shown in the graph in Figure 6. For certain mobile stations, the pace of transmit power updates remains constant. However, the pace of transmission power updates can vary between mobile stations.

【0029】

Of course, other mitigations for the need for simultaneity and coordination can be made consistent with the scope of the invention. In particular, any combination of the above mitigations, such as the situation shown in FIG. 7, is possible.

【0030】

Similarly, a transmit power update, i.e., execution of its update routine in an asynchronous manner, does not require that the time interval between each successive transmit power update cycle be completely irregular. That is, it is necessary to see an attempt of cooperation among various transmission devices. In particular, it is preferable that the transmission power update as described below is performed at a pace of about once per millisecond. This update pace will allow vehicles moving at speeds in the range of 20-50 mph over 850 MHz mobile communications to track signal phasing transitions. As a result, there is a period in which the time interval between each successive transmit power update cycle within a particular transmitter remains constant, or there is substantial coordination between the various transmitters described above. There may be a rest period during the period. The only update of transmit power, i.e., the execution of its update routine in an asynchronous manner, is that there is no perfect simultaneity and coordination between transmitters as shown in FIG. 3 for a period of time. is necessary. Furthermore, it goes without saying that the above-mentioned target value of CIR obtained from the consideration of service quality may be different for each receiving station.

【0031】

One feature and advantage of the method of modifying or updating the transmit power levels of mobile stations according to steps 210-240 above is that those transmit power levels are even faster when the need for simultaneity and coordination is mitigated. , Geometrically converges to the above-mentioned optimum transmission power level. This situation makes it possible to improve system capacity while stipulating that each mobile station or transmitter transmits signals at power levels that allow good data recovery.

【0032】

Another important feature of the present transmission power control method is that the necessity of strict clock synchronization may be alleviated by alleviating the necessity of simultaneity and cooperation between various transmission devices. As specified above, one implication that alleviates the need for strict clock synchronization is that clock or timing devices are no longer needed for cost reasons, reducing the cost of mobile and base stations. It is in.

【0033】

Yet another feature of the method is that convergence occurs even when there is an unpredictable range of propagation delays commonly found in satellite communications. For example, assume that all mobile stations using a particular communication path have already previously updated their transmit power. Then, one particular mobile station is at the next point in time before the effect of the first transmission power correction by the other mobile station is received in the form of interference power at the base station transmitted by the particular mobile station. , It is possible to update its transmission power. Therefore, the particular mobile station updates its transmit power to a power that is unaffected by previous updates of the transmit power level of the other mobile station based on the interfering power measured at the base station. Nevertheless, the transmit power converges exponentially rapidly to the optimum power level. However, as is well understood, a slight increase in propagation delay converges geometrically more rapidly.

【0034】

Mathematical analysis of convergent characteristics The convergent characteristics of the method of the present invention will be described below.

【0035】

Its performance goal is to obtain the following conditional equation (1). That is, [Number 1]

<img file="JPH07336292A_D0001.tif" />Where (CIR)_iIs the CIR of the i-th link, ρ is the pre-determined target value obtained from the consideration of service quality, and M is the link from the mobile station to the base station using the same communication path. Is the number of. The above equation (1) is given by the following equation (2). That is, [Number 2]

<img file="JPH07336292A_D0002.tif" />Where P_iIs the power of the signal transmitted by mobile station i, G_ijIs the gain between base station i and mobile station j, V_iIs the power of locally additive external noise.

【0036】

The performance target defined by the above equation (1) can be described in the form of the following matrix by substituting the above equation (2). That is, [I-ρF] P u, (3 a) P 0, (3 b) Here, P is a vector of transmission power, I is an M × M identity matrix, and F is the following equation, that is, [Number 3]

<img file="JPH07336292A_D0003.tif" />It is a non-negative matrix represented by, and u is the following equation, that is, [Number 4]

<img file="JPH07336292A_D0004.tif" />It is a vector having a matrix component represented by. Assuming that F is an irreducible matrix and u is a positive matrix component, that is, u&gt; 0, the solution of Eq. (3) is feasible if there is at least one solution vector P.

【0037】

In equation (3a), the matrix [I-ρF] has non-positive off-diagonal terms. Such matrices have been found in a myriad of application fields and have been extensively studied. From the general course and rationale, the following description can be obtained.

【0038】

The Perron-Frobenius eigenvalues of the nonnegative irreducible matrix F, which are eigenvalues with the largest coefficients, are real, positive, and unit. Τ it_FExpressed by, the corresponding eigenvector ω is a positive matrix component, and the following equation, that is, [Number 5]

<img file="JPH07336292A_D0005.tif" />It is represented by. This is also said in the following way: (i) ρτ_F &lt;1, the solution of Eq. (ii) (3) exists, (iii) the matrix [I-ρF] exists, and it is a positive matrix component. Equivalent to (5).

【0039】

If the above equation (5) holds, the special solution of equation (3) is P.^*And this is the following equation, that is, [Number 6]

<img file="JPH07336292A_D0006.tif" />It is represented by. In this solution, any other vector P that also satisfies Eq. (3) requires at least equal power to the transmission power from each transmitter, and the transmission power of at least one transmitter is higher. Being big, that is, P P^* It is a Pareto optimal solution that requires the relationship to be.

【0040】

Correspondingly, the CIR of each link is ρ with respect to the transmitted power distribution in Eq. (6). That is, the CIR allowed by the quality of service requirement in equation (1) is extremely low.

【0041】

The model of asynchronous output relaxation is [Number 7]

<img file="JPH07336292A_D0007.tif" />Here, n is an index indicating the so-called "update count" of the transmission power of the mobile station. The update is an event at least one mobile station that is modifying its own transmit power. The set U (n) represents a set of indexes indicating mobile stations that are updating at the same time. Therefore U (n) is a subset of (1,2, ..., M). Therefore, the number of mobile stations updating or modifying their own transmission power can range from just one mobile station to all mobile stations updating their own transmission power at the same time. .. The time interval between each continuous update cycle is arbitrary.

【0042】

In equation (7), the so-called "delay period" d (n, i, j) is a non-negative finite integer. Between the nth update of the transmit power of link i and the (n + 1) th update, various other links can probably update their transmit power more than once. Given that j is an index indicating any such link, the outline is copied into equation (7) by making d (n, i, j) equal to the number of such updates. .. Similarly, the effects of propagation delays are modeled by the proper selection of delay periods.

【0043】

Furthermore, the following is assumed. (A1) P_i(0)&gt; 0 (i = 1,2, ..., M) (A2) Each delay period is evenly divided. That is, the following relationship, [Number 8]

<img file="JPH07336292A_D0008.tif" />There is. (A3) There is such a finite integer s in which each mobile station updates its transmission power at least once for every s consecutive updates.

【0044】

The following verification concept holds for an extended system in which the magnitude of the state vector is increased in consideration of the delay d in the worst case of diagonal dominance due to the rows of the matrix. The diagonal predominance gives the natural Lyapunov function by Eq. (9), which will be described later.

【0045】

The required proposition is that if the above equation (5) holds in the situation where the above (A1), (A2) and (A3) are assumed, the synchronous model of the equation (7) converges rapidly geometrically. To do. That is, the following equation (8) is obtained.

[Number 9]

<img file="JPH07336292A_D0009.tif" />Here, this norm is given by the following equation (9), that is, [Number 10]

<img file="JPH07336292A_D0010.tif" />It is determined from the viewpoint of the Perron-Frobenius eigenvalue ω related to.

【0046】

Its convergent characteristics can be demonstrated by the following verification. P in equations (7) and (6)^*From the definition of, the following equation (10), that is, [Number 11]

<img file="JPH07336292A_D0011.tif" />Is obtained. Where X_iRegarding (n), the following equation (11), that is, [Number 12]

<img file="JPH07336292A_D0012.tif" />There is a relationship. In the case of i U (n), the following equation, that is, [Number 13]

<img file="JPH07336292A_D0013.tif" />There is a relationship. This last equation is the following equation (12), that is, [Number 14]

<img file="JPH07336292A_D0014.tif" />Can be rewritten in the form of. Similarly, if i U (n), then the following equation, ie [Number 15]

<img file="JPH07336292A_D0015.tif" />There is a relationship. Therefore, TheX_d(n) The does not increase with increasing n.

【0047】

Next, the following equation (13), that is, [Number 16]

<img file="JPH07336292A_D0016.tif" />Relationship can be clarified. Here, in order to demonstrate Eq. (13), the transmission power of link i needs to be updated at least once during a set of consecutive update cycles [n'-s, n'-1]. It should be noted that. If the last update is represented with an index τ, then the following equation, ie [Number 17]

<img file="JPH07336292A_D0017.tif" />There is a relationship.

【0048】

From the definitions in equations (13) and (9), the following equation (14), that is, [Number 18]

<img file="JPH07336292A_D0018.tif" />Is obtained. The propositions asserted in Eqs. (8) and (9) can be found directly from Eqs. (14).

【0049】

Preferred Examples FIG. 8 is a flow chart showing a preferred embodiment of the method of the present invention. One specific example of predicting signal path gain is a method that involves the use of pilot signals, which is well known in the art. In step 305, for example, the mobile station 20 generates a pilot signal at a predetermined transmit power level. Subsequently, in step 310, the pilot signal is transmitted from the mobile station 20 and received by the base station 11, and the transmission power level of the base station 11 is measured in step 315. In step 320, the measured value of the base station 11 is used together with the predetermined power level of the pilot signal transmitted from the mobile station 20 and the antenna gain of the base station 11, and the pilot signal transmitted by the mobile station 20 is used. The signal path gain is calculated by multiplying the inverse of the predetermined power level of, the power of the received signal measured in step 315, and the inverse of the antenna gain of the base station.

【0050】

In step 335, the common communication path interference power level at base station 11 is measured or calculated. In step 340, the product of the pre-determined target value of the CIR, the reciprocal of the calculated signal path gain, and the measured common communication path interference power level is calculated. Next, in step 342, transmission power control data including the calculated product value is transmitted to the mobile station 20. Alternatively, instead of executing steps 340 and 342 just described, in step 344, the base station 11 first transmits the transmission power control data to the mobile station 20. This transmit power control data includes the calculated signal path gain, the measured common communication path interference power level, and the pre-determined target value of the CIR. Subsequently, in step 346, the mobile station 20 calculates the product of the pre-determined target value of the CIR, the reciprocal of the calculated signal path gain, and the power level of the measured common communication path interference. Will be done. The difference between these two options is primarily the difference in whether the product is calculated at base station 11 or at mobile station 20.

【0051】

In step 355, the mobile station 20 determines whether the calculated product is higher than the maximum permissible power level for the mobile station 20. If the calculated product is higher than the maximum permissible power level, the transmit power of the mobile station is modified or updated to that maximum permissible power level, as shown in step 360. If the calculated product is not higher than the maximum allowable power level, the mobile station 20 determines in step 365 whether the calculated product is lower than the minimum allowable power level for the mobile station 20. If the calculated product is lower than the minimum permissible power level, the transmit power of the mobile station is updated or modified to that minimum permissible power level, as shown in step 370.

【0052】

Finally, in step 375, if the calculated product is not lower than the minimum allowable power level, the mobile station 20 corrects its transmit power level to the calculated product. Once the transmit power level has been modified or updated at mobile station 20 in any of steps 360, 370 or 375 above, the entire process is repeated back to the starting point in step 305. As mentioned above, each of the other mobile stations 21-24 also adjusts the power of the signals they transmit according to the above routine.

【0053】

FIG. 9 shows a pair of transceivers 400 and 401 for performing the first embodiment of the present invention. Each pair of transceivers 400 and 401 can be one of the base stations and mobile stations in the cellular mobile radio system 1. For example, the transceiver 400 can be the base station 11 and the transceiver 401 can be the mobile station 20. But, of course, the roles of those two transceivers can be reversed. Further, it is assumed that these transceivers 400 and 401 can communicate through a full-duplex wireless communication path. For this purpose, the transceiver 400 has a receiver 410 for receiving a radio signal transmitted in the first frequency band by the transceiver 401. Similarly, the transceiver 401 has a receiver 450 for receiving the radio signal transmitted by the transceiver 400 in the second frequency band, and a transmitter 452 for transmitting the radio signal in the first frequency band. There is.

【0054】

Transceiver 401 has antenna 455 connected to receiver 450 and transmitter 452. A pilot signal generator 460 that generates a pilot signal transmitted from the transceiver 401 at a predetermined power level is connected to the antenna 455. Transceiver 401 also has a storage device 465 for storing information such as transmit power control data received from transceiver 400 or transmit power control data calculated by the transceiver 401 itself. In the first embodiment shown in FIG. 9, the storage device 465 stores the calculated signal path gain, the measured common communication path interference power level, and the pre-determined target value of the CIR, respectively. It has files 466 to 468 to be processed.

【0055】

The storage device 465 is further connected to an arithmetic processing unit 475 such as a central processing unit. The arithmetic processing unit 475 is programmed with a function 476 that searches the transmission power control data currently stored in the storage device 465 in response to an electric signal received from the clock device 472. The clock device 472 typically supplies a signal having a substantially constant rate to the arithmetic processing unit 475. However, the clock device 472 can be an inexpensive asynchronous timing device. The arithmetic processing unit 475 also has a function for calculating the product of the pre-determined target value of the CPU, the measured common communication path interference power level, and the reciprocal of the calculated signal path gain. 477 is programmed.

【0056】

Further, the arithmetic processing unit 475 is programmed with a function 478 for determining whether the calculated product is larger than the maximum allowable power or less than the minimum allowable power. In the arithmetic processing unit 475, if the calculated product is larger than the maximum allowable value, the calculated product is modified to be set equal to the maximum allowable value. Similarly, in the arithmetic processing unit 475, if the calculated product is less than the minimum allowable value, the calculated product is modified to be set equal to the minimum allowable value. Other than these, the arithmetic processing unit 475 does not change the value of the calculated product.

【0057】

The output end of the arithmetic processing unit 475 is connected to the transmission power control circuit 471. The transmit power control circuit 471 is connected to the transmitter 452 and adjusts the power of the signal transmitted by the transmitter 452 according to the values determined by the above functions 477 and 478. As a result, when the calculated product is within the range of the maximum power level and the minimum power level, the power of the signal transmitted by the transmitter 452 is transmitted by the transmitter 452 first in the transmission power control circuit 471. The value obtained by multiplying the power of the signal to be obtained by the gain of the antenna 455 is adjusted to be equal to the value of the product calculated by the arithmetic processing device 475.

【0058】

Transceiver 400 also has an antenna 415 connected to receiver 410 and transmitter 412. The antenna 415 has a predetermined gain. The antenna 415 is also connected to a pilot signal detection circuit 420 for detecting the received power level of the pilot signal transmitted by the transceiver 401. A common communication path interference power (CCIP) detection circuit for detecting the power level of common communication path interference in the receiver 410 is also connected to the receiver 410. The storage device 425 is connected to the pilot signal detection circuit 420 and the CCIP detection circuit 421. The storage device 425 has a file 426 for storing the current value of the power level of the received pilot signal and a file 427 for storing the common channel interference power level. The storage device 425 also contains files 428 to 430 for storing the predetermined power level of the pilot signal transmitted by the transceiver 401, the gain of the antenna 415, and the predetermined target value of the CIR, respectively. Have.

【0059】

An arithmetic processing unit 435 such as a central processing unit is connected to the storage device 425 and the transmitter 412. The arithmetic processing unit 435 is programmed with a function 436 for retrieving information stored in the storage device 425. The arithmetic processing unit 435 is also programmed with a function 437 for calculating the signal path gain based on the power level of the received pilot signal as described above. The arithmetic processing device 435 further receives transmission power control data including the target value set in advance of the CIR, the measured common communication path interference power level, and the calculated signal path gain. Function 438 is programmed to instruct transmitter 412 to transmit to transceiver 401.

【0060】

FIG. 10 shows a pair of transceivers 500 and 501, which is a second embodiment. As in the case of the pair of transceivers 400 and 401, the transceivers 500 and 501 can be one of the base stations and mobile stations in the system 1, respectively. As mentioned above, transceivers 500 and 501 are assumed to be capable of communicating through a full-duplex wireless communication path. As in the first embodiment, of course, the roles of the two transceivers 500 and 501 can be reversed. In the above two embodiments, one of the pair of transceivers is the product of the pre-determined target value of the CIR, the measured common communication path interference power level, and the calculated signal path gain. The main difference is that it has an element for calculating.

【0061】

The transceiver 500 has a receiver 510 for receiving a radio signal transmitted in the first frequency band by the transceiver 501. Similarly, the transceiver 501 has a receiver 550 for receiving the radio signal transmitted by the transceiver 500 in the second frequency band, and a transmitter 552 for transmitting the radio signal in the first frequency band. ing.

【0062】

Transceiver 501 has an antenna 555 connected to receiver 550 and transmitter 552. A pilot signal generator 560 that generates a pilot signal transmitted from the transceiver 501 at a predetermined power level is connected to the antenna 555. Transceiver 501 also has a storage device 565 for storing information such as transmit power control data received from transceiver 500. The storage device 565 is connected to the receiver 550 and multiplies the pre-determined target value of the CIR by the reciprocal of the calculated signal path gain and the measured common communication path interference power level. It has a file 570 for storing the calculated product. In this second embodiment, the product is stored in file 570 after being transmitted from transceiver 500 to transceiver 501.

【0063】

An arithmetic processing unit 575, such as a central processing unit, is programmed with a function 576 that retrieves the contents of file 570 in response to a signal from clock device 572, which can have a configuration similar to that of clock device 472. .. As in the first embodiment, the arithmetic processing unit 575 has a function for determining whether the value retrieved from the file 570 is larger than the maximum allowable power or less than the minimum allowable power 578. Is programmed. The arithmetic processing unit 575 further sets the searched value equal to the maximum permissible power when the searched value is larger than the maximum permissible power, and searches for the searched value when it is less than the minimum permissible power. It is programmed to make modifications to set the value equal to the minimum permissible value. Other than these, the arithmetic processing unit 575 does not change the value retrieved from file 570.

【0064】

Furthermore, as in the first embodiment, the output end of the arithmetic processing unit 575 is connected to the transmission power control circuit 571. The transmission power control circuit 571 adjusts the power of the signal transmitted by the transmitter 552 according to the value received from the arithmetic processing unit 575. As a result, when the calculated product is within the range of the maximum power level and the minimum power level, the power of the signal transmitted by the transmitter 552 multiplied by the gain of the antenna 555 is transmitted by the transceiver 500 first. It is adjusted to be equal to the value of the above product.

【0065】

The transceiver 500 also has an antenna 515, a receiver 510 and a transmitter 512 configured as in the first embodiment. The antenna 415 has a predetermined gain. The antenna 515 is also connected to a pilot signal detection circuit 520 for detecting the received power level of the pilot signal transmitted by the transceiver 501. Further, a common communication path interference power (CCIP) detection circuit 521 is connected to the receiver 510 in order to detect the power level of the common communication path interference in the receiver 510. The storage device 525 is connected to the pilot signal detection circuit 520 and the CCIP detection circuit 521. The storage device 525 has a file 526 for storing the current value of the power level of the received pilot signal and a file 527 for storing the common channel interference power level. The storage device 525 also has files 528 to 530 for storing the predetermined power level of the pilot signal transmitted by the transceiver 501, the gain of the antenna 515, and the predetermined target value of the CIR, respectively. doing.

【0066】

An arithmetic processing unit 535 such as a central processing unit is connected to the storage device 525, and a function 536 for retrieving information stored in the storage device 525 is programmed. The arithmetic processing unit 535 is also programmed with a function 537 for calculating the signal path gain based on the power level of the received pilot signal as described above. The arithmetic processing unit 535 further calculates the product by multiplying the previously determined target value of the CIR, the measured common communication path interference power level, and the calculated signal path gain with each other. Function 539 is programmed. Finally, the arithmetic processing unit 535 is programmed with a function 540 for instructing the transmitter 512 to transmit the power control data including the calculated product to the transceiver 501.

【0067】

[Effect of the invention]

As described above, according to the present invention, the need for simultaneity and coordination between a plurality of transmitting devices is alleviated, and as a result, an expensive clock device or timing device is not required, and therefore the cost of transmitting power control is reduced. Has the effect of being reduced.

【0068】

It should be noted that the reference numerals described in the claims are for facilitating the understanding of the invention and should not be understood to limit the claims.

[Simple explanation of drawings]

[Figure 1]

It is a figure which shows an example of the cellular mobile radio system in which the method of this invention is particularly useful.

[Figure 2]

FIG. 6 is a flow chart showing each step of an update routine for adjusting the power of a signal transmitted by a mobile station in a cellular radio system according to the method of the invention.

[Fig. 3]

It is a figure which shows an example of the timing diagram which the electric power of the signal transmitted by a plurality of mobile stations is adjusted by the method which is simultaneous and cooperative.

[Fig. 4]

FIG. 5 shows an example of a timing diagram in which the power of a signal transmitted by a plurality of mobile stations is adjusted in a manner that does not require simultaneity between the mobile stations.

[Fig. 5]

FIG. 5 illustrates a second example of a timing diagram in which the power of a signal transmitted by a plurality of mobile stations is adjusted in a manner that does not require simultaneity between the mobile stations.

[Fig. 6]

FIG. 5 shows a third example of a timing diagram in which the power of a signal transmitted by a plurality of mobile stations is adjusted in a manner that does not require simultaneity between the mobile stations.

[Fig. 7]

FIG. 5 shows a fourth example of a timing diagram in which the power of a signal transmitted by a plurality of mobile stations is adjusted in a manner that does not require simultaneity between the mobile stations.

[Fig. 8]

It is a flow chart which shows the preferable execution example of the update routine by the method of this invention.

[Fig. 9]

It is a figure which shows the 1st Example of the pair of a mobile station and a base station by the method of this invention.

[Fig. 10]

It is a figure which shows the 2nd Example of the pair of a mobile station and a base station by the method of this invention.

[Explanation of symbols]

1 Cellular mobile wireless system C1-C7 cell 10-16 base station 20-24 mobile station 30 system controller 40 wiring 400 transceiver 401 transceiver 410 receiver 412 transmitter 415 antenna 420 Pilot signal detection circuit 421 CCIP detection circuit 425 Storage device 426-430 file 435 Arithmetic processing unit 436-438 Functional program 450 receiver 452 transmitter 455 antenna 460 Pilot signal generator 465 storage device 466-468 files 471 Transmission power control circuit 472 Clock device 475 Arithmetic processing unit 476-478 Functional program 500 transceiver 501 transceiver 510 receiver 512 transmitter 515 antenna 520 Pilot signal detection circuit 521 CCIP detection circuit 525 storage device 526-530 file 535 Arithmetic processor 536 functional programs 537 functional program 539 Functional program 540 Functional program 550 receiver 552 transmitter 555 antenna 560 Pilot signal generator 565 storage device 570 files 571 Transmission power control circuit 572 clock device 575 Arithmetic processing unit 576 functional programs 578 feature program