Abstract:
A CDMA apparatus including a propagation path variation estimator for estimating propagation path variations between respective prior transmit power control sections and a current transmit power control section to obtain propagation path variation estimation values, wherein each of the propagation path variation estimation values is obtained by estimating a propagation path variation between a different corresponding prior transmit power control section and the current transmit power control section; propagation path variation correction part for generating a plurality of corrected products, each corrected product obtained by multiplying at least one of vector, amplitude and/or power of a received signal of the different corresponding prior transmit power control section by said propagation path variation estimation value obtained by estimating the propagation path variation between the different corresponding prior transmit power control section and the current transmit power control section; and averaging part for averaging the plurality of corrected products.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional application of commonly assigned, U.S. patent application Ser. No. 09/619,361, filed Jul. 19, 2000, now U.S. Pat No. 6,999,427 and entitled “CDMA reception apparatus and received signal power measuring apparatus in CDMA communication system”, which application is incorporated herein by reference in its entirety. That application claims priority to Japanese patent application serial number 11-206789 filed Jul. 21, 1999. 

   FIELD OF THE INVENTION 
   The present invention relates to a mobile communication reception apparatus in mobile communications applied with digital radio communication system, particularly with CDMA (code division multiple access) system, more specifically to received signal power measurement for transmit power control. 
   BACKGROUND OF THE INVENTION 
   An example of relationship between flow of transmit power control of CDMA mobile communication system by the prior art and radio slot configuration is schematically shown in  FIG. 1 . 
   As shown in  FIG. 1 , 1) received signal power measurement is performed for each transmit power control section (hereinafter referred to as “slot”), 2) the measurement result is subjected to a division calculation using a measurement result of noise interference power to obtain a received SNIR (signal power to interference power ratio), the received SNIR is compared with a reference SNIR, 4) a transmit power control bit is transmitted designating a transmit power control indicator of the received side channel, so that when the comparison result exceeds the reference SNIR, a base station transmit power is decreased, or when the comparison result is below the reference SNIR, the base station transmit power is increased. 
   As shown in  FIG. 1 , in the traffic channel, there exists not only a fixed transmit part (shaded in  FIG. 1 ) in which the number of transmit bits is unchanged, but also a variable transmit part in which the transmit bit number is successively changed according to a change in information speed of transmitted data, when there is no data, transmit is stopped. In this case, the fixed transmit part is applied to received signal power measurement. 
   As shown above, received signal power measurement in a CDMA reception apparatus is performed using a fixed transmit part, however, there is a problem that when signal power of the fixed transmit part is small, measurement accuracy of received signal power is deteriorated, and transmit power control is not performed with good accuracy. 
   As described above, accuracy degradation of transmit power control has resulted in an increase in transmit power and deterioration of channel capacity. 
   BRIEF SUMMARY OF THE INVENTION 
   In a first aspect of the present invention, there is provided a CDMA reception apparatus comprising propagation path variation estimation means for estimating propagation path variations between respective prior transmit power control sections and a current transmit power control section to obtain propagation path variation estimation values, wherein each of the propagation path variation estimation values is obtained by estimating a propagation path variation between a different corresponding prior transmit power control section and the current transmit power control section; propagation path variation correction means for generating a plurality of corrected products, each corrected product obtained by multiplying at least one of vector, amplitude and/or power of a received signal of the different corresponding prior transmit power, control section by said propagation path variation estimation value obtained by estimating the propagation path variation between the different corresponding prior transmit power control section and the current transmit power control section; and averaging means for averaging the plurality of corrected products. 
   In a second aspect of the present invention, there is provided a CDMA reception apparatus comprising transmit power changing amount estimation means for estimating changing amounts of transmit power of a communication partner station varied by transmit power control between respective prior transmit power control sections and a current transmit power control section to obtain transmit power changing amount estimation values, wherein each of the transmit power changing amount estimation values is obtained by estimating a transmit power changing amount between a different corresponding prior transmit power control section and the current transmit power control section; transmit power changing amount correction means for generating a plurality of corrected products, each corrected product obtained by multiplying at least one of vector, amplitude and/or power of a received signal of the different corresponding prior transmit power control section by said transmit power changing amount estimation value obtained by estimating the transmit power changing amount between the different corresponding prior transmit power control section and the current transmit power control section; and averaging means for averaging the plurality of corrected products. 
   In accordance with a third aspect of the present invention, there is provided a received signal power measurement method of a CDMA reception apparatus, comprising a propagation path variation estimation step for estimating propagation path variations between respective prior transmit power control sections and a current transmit power control section to obtain propagation path variation estimation values, wherein each of the propagation path variation estimation values is obtained by estimating a propagation path variation between a different corresponding prior transmit power control section and the current transmit power control section; a propagation path variation correction step for generating a plurality of corrected products, each corrected product obtained by multiplying at least one of vector, amplitude and/or power of a received signal of the different corresponding prior transmit power control section by said propagation path variation estimation value obtained by estimating the propagation path variation between the different corresponding prior transmit power control section and the current transmit power control section; and an averaging step for averaging the plurality of corrected products. 
   In accordance with a fourth aspect of the present invention, there is provided a received signal power measurement method of a CDMA reception apparatus, comprising: a transmit power changing amount estimation step for estimating changing amounts of transmit power of a communication partner station varied by transmit power control between respective prior transmit power control sections and a current transmit power control section to obtain transmit power changing amount estimation values, wherein each of the transmit power changing amount estimation values is obtained by estimating a transmit power changing amount between a different corresponding prior transmit power control section and the current transmit power control section; a transmit power changing amount correction step for generating a plurality of corrected products, each corrected product obtained by multiplying at least one of vector, amplitude and/or power of a received signal of the different corresponding prior transmit power control section by said transmit power changing amount estimation value obtained by estimating the transmit power changing amount between the different corresponding prior transmit power control section and the current transmit power control section; and an averaging step for averaging the plurality of corrected products. 
   The above and other features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagram schematically showing an example of relationship between flow of transmit power control of a prior art CDMA mobile communication system and radio slot configuration; 
       FIG. 2  is a block diagram showing an example of construction of reception apparatus in the CDMA mobile terminal in an embodiment 1 of the present invention; 
       FIG. 3  is a block diagram showing an example of construction of a received SNIR measurement part  208  in  FIG. 2 ; 
       FIG. 4  is a diagram showing the relationship of  FIGS. 4A and 4B . 
       FIG. 4A  is a block diagram showing an example of construction of a received signal power measurement part  304  in  FIG. 3 ; 
       FIG. 4B  is a block diagram showing an example of construction of a received signal power measurement part  304  in  FIG. 3 ; 
       FIG. 5  is a block diagram showing an example of construction of a propagation path estimation part to which the present invention is applied; 
       FIG. 6  is a block diagram showing an example of construction of a transmit power changing amount estimation part to which the present invention is applied; 
       FIG. 7  is a block diagram showing an example of construction of a received signal power measurement part in an embodiment 2 of the present invention; 
       FIG. 8  is a flow chart for explaining a setting method of averaging section in the embodiment 1 of the present invention; 
       FIG. 9  is a flow chart for explaining a setting method of a forgetting factor α in embodiment 2 of the present invention; and 
       FIG. 10  is a flow chart showing an example of operation of a received signal power measurement part. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In the following, embodiments of the present invention will be described with reference to the drawings. 
   The present invention can be applied to a base station reception apparatus as an uplink receiver, however, because the above-described estimation of propagation path variation can be performed by a channel not performing the transmit power control, an example of downlink receiver, that is, a case where a reception apparatus of a mobile communication terminal is used will be described as the following embodiment. 
   Embodiment 1 
     FIG. 2  is a block diagram showing an example of construction of a reception apparatus in a CDMA mobile terminal in the embodiment 1 of the present invention. 
   A reception apparatus  200  includes a reception radio part  202 , a despreader  204 , a received data demodulator  206 , a received SNIR measurement part  208  and a SNIR comparator  212 . 
   The reception radio part  202  receives a radio signal transmitted from a radio base station, performs frequency conversion and filtering, and outputs a baseband signal. 
   In the despreader  204 , despreading of the baseband signal is performed, and a received despread signal is outputted to the received data decoder  206  and a received SNIR calculator  208 . 
   In the received data demodulator  206 , RAKE combining, error correction decoding and the like are performed to demodulate the received data. At the same time, the received despread signal is inputted to the received SNIR measurement part  208  to output a received SNIR at every slot, a comparison of the outputted value with a target SNIR  210  is performed in the SNIR comparator  212 , according to the comparison result, a transmit power control bit  214  (transmit power control indicator) to be transmitted is outputted. 
     FIG. 3  is a block diagram showing an example of construction of the received SNIR measurement part  208  in  FIG. 2 . 
   The received SNIR measurement part  208  comprises a received signal power measurement part  304 , a noise interference power measurement part  306  and a divider  308 . 
   The received despread signal  302  outputted from the despreader  204  is inputted respectively to the received signal power measurement part  304  and the received noise interference power measurement part  306 , and the respective measurement results A and B are divided in the divider  308  to obtain a received SNIR  310 . 
     FIGS. 4A and 4B  is a block diagram showing an example of construction of the received signal power measurement part  304  in  FIG. 3 . 
   Here, in  FIGS. 4A and 4B , alphabet n shows a present number of slots, and K a maximum number of received signal slots for performing averaging. 
   The received signal power measurement part  304  includes a RAKE combiner  404 , a delayer  406 , a propagation path estimator  407 , a transmit power changing amount estimator  409 , an averaging part  412 , a received signal power calculator  414 , and an averaging section setting part  416 . 
   The received despread signal  402  of fixed transmit part of the dedicated traffic channel is RAKE combined by the RAKE combiner  404 , and an average value of received signal of each slot is stored in the delayer  406 . The stored value can be any of vector, amplitude and/or power. Received signal of past slots stored in the delayer  406  is multiplied by the multiplier with the propagation path variation estimation value  408  of the past slot timing and the present timing generated in the propagation path estimator  407 . Further, after multiplication by the multiplier with the estimation value  410  of changing amount of transmit power by transmit power control of the past slot timing and the present timing, averaging is performed along with the present slot in the averaging part  412 . Still further, when the stored value is vector or amplitude, it is converted into power by the received signal power calculator  414 , and outputted as received signal power. 
   In the averaging section setting part  416 , as will be described later, the averaging section is appropriately set according to the propagation environment and environment of the system in communication. 
     FIG. 10  is a flow chart showing an example of operation of the received signal power measurement part  304 . 
   First, received despread signal  402  of fixed transmit part of a dedicated traffic channel is RAKE combined by the RAKE combiner  404  (step S 1002 ). 
   Next, an average value of received signal of each slot is stored in the delayer  406  (step S 1004 ). The stored value can be any of vector, amplitude and/or power. 
   Next, in the propagation path estimator  407 , propagation path variation in the present transmit control section is estimated from information of respective past transmit power control sections to obtain a propagation path variation estimation value  408  (step S 1006 ). 
   Next, at least one of vector, amplitude and/or power of received signals of a plurality of transmit power control sections is corrected by multiplying using the propagation path variation estimation value  408  obtained by the propagation path estimator  407  (step S 1008 ). 
   Next, in the transmit power changing amount estimator  409 , a changing amount of transmit power changed by transmit power control of the communication partner station in the present transmit power control section is estimated from information of past respective transmit power control sections (for example, past transmit power control bit data stored in any of storage apparatus (not shown) in the reception apparatus) to obtain a transmit power changing amount estimation value  410  (step S 1010 ). 
   Next, at least one of vector, amplitude and/or power of received signals of a plurality of transmit power control sections is corrected by multiplying using the transmit power changing amount estimation value  410  obtained by the transmit power changing amount estimator  409  (step S 1012 ). 
   Next, in the averaging part  412 , at least one of vector, amplitude and/or power of the corrected received signals of the plurality of transmit power control sections is averaged (step S 1014 ). 
   Next, an averaging section setting method in the averaging section setting part  416  will be described with reference to  FIG. 8 . 
   First, for example, the amount of power allocated to the fixed transmit part of signal from the communication partner station corresponding to the shaded part in  FIG. 1  is judged from the channel format in communication (step S 802 ), setting is made so that the averaging section is decreased when the power is large (step S 804 ), or the averaging section is increased when the power is small (step S 806 ). Alternatively, a judgment is made from informed information from the system as to whether or not there is a common channel transmitted without performing transmit power with the same antenna and directivity and propagation path estimation is possible (step S 808 ), when propagation path estimation is possible the averaging section is increased (step S 810 ), or when propagation path estimation is impossible the averaging section is decreased (step S 812 ). On the other hand, when propagation path estimation is not performed, traveling speed of the traveling machine is detected (step S 814 ), when the traveling speed is high and variation of propagation path is large, the averaging section is set small (step S 816 ), or when the traveling speed is low and variation of propagation path is small, the averaging section is set large (step S 818 ). 
     FIG. 5  is a block diagram showing an example of construction of the propagation path estimator  407  in  FIGS. 4A and 4B . 
   Here, alphabet n in  FIG. 5  shows a present slot number, and K a slot number of largest received signal for averaging. 
   The propagation path estimator  407  includes a delayer  504  and a divider  506 . 
   In the propagation path estimator  407 , amplitude of a received signal  502  after RAKE combining of the common channel not performing transmit power control is stored in the delayer  504  for each slot, by performing division calculation A/B of the received signal A of the present slot and the received signal B of respective past slot in the divider  506 , thereby outputting a propagation path variation estimation value  508  of the present slot from the past respective slots. 
     FIG. 6  is a block diagram showing an example of construction of the transmit power changing amount estimator  409  in  FIGS. 4A and 4B . 
   Here, alphabet n in  FIG. 6  shows a present slot number, and K a slot number of largest received signal for averaging. 
   The transmit power changing amount estimator  409  includes a transmit power changing amount converter  604  and a delayer  606 . 
   The transmit power changing amount estimator  409  estimates a changing amount of transmit power from a radio base station from the transmit power control bit  602  transmitted by the mobile terminal to the radio base station. 
   First, in the transmit power changing amount converter  604 , the transmit power control bit  602  transmitted from the mobile terminal is converted into a transmit power changing amount to obtain a transmit power control estimation value  608 . Next, output after changing is multiplied with the transmit power changing amount from each slot timing up to the present stored in the delayer  606  to obtain a new transmit power control estimation value  608 . 
   Embodiment 2 
   In the following, an embodiment 2 according to the present invention will be described with reference to  FIG. 7 . 
     FIG. 7  is a block diagram showing an example of construction of a received signal power measurement part in the embodiment 2 of the present invention. In the receiver, construction other than the received signal power measurement part is similar to that in the embodiment 1. 
   A received signal power measurement part  700  in the embodiment 2 includes an a multiplier  702 , a delayer  704 , a propagation path estimator  705 , a transmit power changing amount estimator  707 , a received signal power calculator  710 , an averaging section setting part  712 , a RAKE combiner  716  and a 1−α multiplier  718 . 
   The delayer  704 , the propagation path estimator  705 , the transmit power changing amount estimator  707 , the received signal power calculator  710 , the averaging section setting part  712 , and the RAKE combiner  716  have the same functions as those described in  FIGS. 4 to 9 , and the α multiplier  702  and the 1−α multiplier respectively have functions for multiplying the input with α or 1−α. 
   The received signal power measurement part  700  has a form of a feedback type filter which performs averaging of the received signal of the present slot and the received signal of the past slot using a forgetting factor α  702 . That is, for the received signal of the past slot stored in the delayer  704 , after multiplication with the propagation path variation estimation value  706  between 1 slot previous timing and the present timing and the transmit power changing amount estimation value  708 , it is multiplied with the forgetting factor α in the a multiplier  702  to perform averaging with the received signal of the present slot. In the received signal power calculator  710 , a received signal power is calculated from received signal after averaging and the result is outputted. On the other hand, received signal after averaging is stored again in the delayer  704 . In the averaging section setting part  712 , α is appropriately set according to the propagation environment and details of the system in communication. 
   Next, setting method of the forgetting factor α will be described with reference to  FIG. 9 . 
   First, for example, the amount of power allocated to the fixed transmit part of signal from the communication partner station corresponding to the shaded part in  FIG. 1  is judged from the channel format in communication (step S 902 ), setting is made so that α is decreased when the power is large (step S 904 ), or α is increased when the power is small (step S 906 ). Alternatively, a judgment is made from informed information from the system as to whether or not there is a common channel transmitted without performing transmit power with the same antenna and directivity and propagation path estimation is possible (step S 908 ), when propagation path estimation is possible α is increased (step S 910 ), or when propagation path estimation is impossible α is decreased (step S 912 ). On the other hand, when propagation path estimation is not performed, traveling speed of the traveling machine is detected (step S 914 ), when the traveling speed is high and variation of propagation path is large, α is set small (step S 916 ), or when the traveling speed is low and variation of propagation path is small, α is set large (step S 918 ). 
   Effects of the Invention 
   Effects of Embodiment 1 
   As shown in  FIG. 3 , by obtaining the received signal power by averaging a plurality of slots including past slots, even when the fixed transmit part included in 1 slot is small, the effective measurement bit number can be increased, and received power measurement of higher accuracy can be performed. 
   Further, for the above-shown averaging of a plurality of slots, when a common channel cannot be used for estimation, or when the propagation path fixed transmit part is large, the number of slots for averaging is decreased, or depending on the case, only the present slot is used, averaging by an appropriate averaging slot number can be performed without changing the construction of the receiver and measurement algorithm, whereby high quality communication, reduction of transmit power, and increased channel capacity can be achieved, and complexity of the mobile terminal can be suppressed. 
   Effects of Embodiment 2 
   With the construction as in the embodiment 2, the same effects as shown in embodiment 1 can be obtained, and averaging of the received signal power is performed by weighting average using the forgetting factor α, buffers such as delayer for storing past received signals can be reduced. 
   For example, in embodiment 1, averaging of a plurality of slots is calculated by Formula 1 shown below.
 
averaged R   —   n =( R   —   n+R   —   {n− 1 }+R   —   {n− 2 }+R   —   {n− 3})/4  [FORMULA 1]
 
   The formula (1) is a formula for averaging using past 4 slots, in which R_n shows a received power value of n&#39;th slot. Further, for simplicity of description, cancel due to variation is not considered. 
   While, an ordinary averaging using FIR filter as shown above is performed in embodiment 1, averaging in embodiment 2 is represented by
 
averaged R   —   n=Rn *α+averaged R   —   {n− 1}*(1−α)  [FORMULA 2]
 
and exponential weighted averaging (averaging using IIR filter) is performed using the forgetting factor α. For example, when it is assumed as α=0.25, the same averaging effect as averaging of about 4 slots can be obtained. Therefore, by performing such exponential weighted averaging, only one previous value (in the above formula, averaged R_(n−1)) of past received power value may be stored, thereby reducing the calculation amount.
 
   Further, the propagation path variation estimation value and the transmit power changing amount estimation value are also calculation for immediately 1 slot previous values, and the calculation amount can be reduced. 
   Still further, when the effect of the value using received signals of past slots is to be changed, it can be achieved by changing the factor α. 
   The present invention has been described in detail with respect to various embodiments, and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and it is the intention, therefore, in the appended claims to cover all such changes and modifications as fall within the true spirit of the invention.