Patent Document

This is a division of application Ser. No. 08/905,558, filed Aug. 4, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a communication apparatus having a transmission electric power control circuit, a communication apparatus having a control signal generation circuit generating a control signal indicative of compensating a table for determining a transmission power and a communication system in which transmission electric power is controlled. 
     2. Description of the Prior Art 
     A communication apparatus having a transmission electric power control circuit is disclosed in Japanese patent application provisional publication No. 6-13956. In such a prior art communication apparatus, a transmission electric power is determined in accordance with an electric power of the received pilot signal. The pilot signal is detected by a mobile unit and used to estimate the power of transmission of the mobile unit. A spread spectrum communication equipment with transmission power control is also disclosed in Japanese patent application provisional publication No. 08032513A. In such a prior art spread spectrum communication equipment, a transmission power of a base station is determined in accordance with a detected control bit from a mobile unit. 
     There are two types of controlling transmission power in mobile unit communication employing the CDMA system, that is, an open loop control effected by a mobile unit in accordance with the detected electric power of the received signal and a closed loop control effected by feeding back a control signal to a mobile station from a base station. 
     Tomohiro Doi and Mamoru sawahashi disclosed Power control by employing Interference Power for DS-CDMA in TECHNICAL REPORT OF IEICE. A P94-75, RCS94-99 (1994-10) at p63-68 by THE INSTITUTE OF ELECTRONICS. INFORMATION AND COMMUNICATION ENGINEERS. A transmission power at a mobile unit is controlled such that a signal to Interference-plus-Noise power Ratio (SINR) is maintained at a constant value at a base station through a transmission power control bit (TPC bit) from the base station to the mobile unit to provide a closed loop controlling. The mobile unit increases or decreases the transmission power in accordance with the TPC bit periodically inserted in a data frame. 
     SUMMARY OF THE INVENTION 
     The aim of the present invention is to provide an improved communication apparatus and an improved communication system. 
     According to the present invention, a first communication apparatus is provided, which comprises: a receiving and transmitting portion having an antenna for receiving a first CDMA radio wave signal, detecting a desired wave component including a control signal from the first CDMA radio wave signal, and transmitting a second CDMA radio wave signal; a detection portion for detecting an electric power of the detected desired wave component; a table portion for storing a relation between the detected electric power and an electric power of the second CDMA radio wave signal to be transmitted, the control signal indicating compensation of the relation; a demodulating and detection portion for demodulating the detected desired wave component and outputting demodulation data and for detecting the control signal from the detected desired wave component; a compensation portion for compensating the relation in accordance with the detected control signal; a determining portion for determined an actual electric power of the second CDMA radio wave signal to be transmitted in accordance with the compensated relation; and a transmission power control portion for controlling a transmission power of the second CDMA radio wave signal in accordance with the actual electric power. 
     The first communication apparatus may further comprise: a sampling and storing portion for sampling and storing the detected electric power; and a compensating range determining portion for determining a portion of a range of the detected electric power in accordance with the stored detected electric power, wherein the compensation portion compensates the relation within the range. 
     In the first communication apparatus, the compensation portion may comprise an allowable range data receiving portion for receiving allowable range data and the compensation portion compensates the relation within the allowable range of the electric power of the second CDMA radio wave signal to be transmitted in accordance with the received allowable range data. 
     According to the present invention, a second communication is provided, which comprises: a transmitting and receiving portion having an antenna for transmitting a first CDMA radio wave signal including a control signal, receiving a second CDMA radio wave signal, and detecting a desired wave component from the second CDMA radio wave signal; an electric power detection portion for repeatedly detecting an electric power of the desired wave component of the received second CDMA radio wave signal; an averaging portion for averaging the repeatedly detected electric power to obtain an average; a comparing portion for obtaining an error between the average and a target value and comparing the error with a predetermined value; and a control signal generation portion for generating the control signal when the error exceeds the predetermined value. 
     According to the present invention, a third communication apparatus is provided, which comprises: a transmitting and receiving portion having an antenna for transmitting a first CDMA radio wave signal including a control signal, receiving a second CDMA radio wave signal, and detecting a desired wave component and interference wave components from the second CDMA radio wave signal; a first electric power detection portion for detecting a first electric power of the desired wave component; a second electric power detection portion for detecting a second electric power of the detected interference wave components; an operation portion for operating a signal to interference power ratio from the detected first and second electric powers; a comparing portion for obtaining an error between the signal to interference power ratio and a target value and comparing the error with a predetermined value; and a control signal generation portion for generating the control signal when the error exceeds the predetermined value. 
     According to the present invention, a fourth communication apparatus is provided, which comprises: a transmitting and receiving portion having an antenna for transmitting a first CDMA radio wave signal including a control signal, receiving a second CDMA radio wave signal; an error rate detection portion for detecting an error rate from the received second CDMA radio wave signal; a comparing portion for obtaining an error between the error rate and a target value and comparing the error with a predetermined value; and a control signal generation portion for generating the control signal when the error exceeds the predetermined value. 
     According to the present invention, a communication system is provided, which comprises a plurality of mobile stations and a base station. Each of the mobile stations comprises: a receiving and transmitting portion having a first antenna for receiving a first CDMA radio wave signal, detecting a first desired wave component including a control signal, and transmitting a second CDMA radio wave signal; a detection portion for detecting an electric power of a first desired wave component of the received first CDMA radio wave signal; a table portion for storing a relation between the detected electric power and an electric power of the second CDMA radio wave signal to be transmitted, the control signal indicating compensation of the relation; a demodulation and detection portion for demodulating the received first desired wave component and outputting demodulation data and for detecting the control signal from the received first desired wave component; a compensation portion for compensating the relation in accordance with the detected control signal; a determining portion for determined an actual electric power of the second CDMA radio wave signal to be transmitted in accordance with the compensated the relation; and a transmission power control portion for controlling a transmission power of the second CDMA radio wave signal in accordance with the actual electric power. 
     The base station comprises: a transmitting and receiving portion having a second antenna for transmitting the first CDMA radio wave signal including the control signal, receiving the second CDMA radio wave signal, and detecting a second desired wave component from the second CDMA radio wave signal; an electric power detection portion for repeatedly detecting an electric power of a second desired wave component of the received second CDMA radio wave signal; an averaging portion for averaging the repeatedly detected electric powers to obtain an average; a comparing portion for obtaining an error between the average and a target value and comparing the error with a predetermined value; and a control signal generation portion for generating the control signal when the error exceeds the predetermined value. 
     In the communication system, each of the mobile stations may further comprise: a sampling and storing portion for sampling and storing the detected electric power; and a compensating range determining portion for determining a portion of a range of the detected electric power in accordance with the stored detected electric power, wherein the compensation portion compensates the relation within the range. 
     In the communication system, the compensation portion comprises an allowable range data receiving portion for receiving allowable range data and the compensation portion compensates the relation within the allowable range of the electric power of the second CDMA radio wave signal to be transmitted in accordance with the received allowable range data. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The object and features of the present invention will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a block diagram of a transmission power control circuit of a first embodiment; 
     FIG. 2 is a graphical drawing showing the power control table in the transmission power determining circuit  104  shown in FIG. 1; 
     FIG. 3 is a block diagram of a communication apparatus according to the first to third embodiments; 
     FIG. 4 is a block diagram of a transmission power control circuit of the second embodiment; 
     FIG. 5 is a graphical drawing illustrating compensation of the transmission power control table in the second embodiment; 
     FIG. 6 is a block diagram of a transmission power control circuit of a third embodiment; 
     FIG. 7 is a graphical drawing illustrating compensation of the transmission power control table in the third embodiment; 
     FIG. 8 is a block diagram of a transmission power control signal generation portion of a fourth embodiment; 
     FIG. 9 is a graphical drawing of the fourth embodiment illustrating obtaining an error; 
     FIG. 10 is a block diagram of a communication apparatus according to the fourth to sixth embodiments; 
     FIG. 11 is a block diagram of a transmission power control signal generation circuit of a fifth embodiment; 
     FIG. 12 is a graphical drawing of the fifth embodiment illustrating obtaining the error; 
     FIG. 13 is a block diagram of a transmission power control signal generation circuit of a sixth embodiment; 
     FIG. 14 is a block diagram of a communication system of a seventh embodiment; and 
     FIG. 15 shows a timing chart of the communication apparatus of the seventh embodiment. 
    
    
     The same or corresponding elements or parts are designated with like references throughout the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     A First Embodiment 
     FIG. 1 is a block diagram of a transmission power control circuit of a first embodiment. 
     A correlation detection output  101  is supplied to a reception power calculation circuit  102 . The reception power calculation circuit  102  calculates a reception power of a desired wave component at an antenna. A calculated reception power is supplied to a transmission power determining circuit  104 . The transmission power determining circuit  104  determines a transmission power setting value  107  from the calculated reception power in accordance with an initial setting value from an initial setting value storing circuit  103  through a power control table included therein in a power on condition or a reset-start condition. During communication, i.e., in a normal condition, a compensation circuit  106  compensates the power control table stored in the transmission power determining circuit  104  in accordance with a control bit (hereinafter referred to as a sc bit) indicative of compensating the transmission power table which represents a relation between a reception power and a transmission power. The transmission power determining circuit  104  determines the transmission power setting value in accordance with the calculating reception power through the compensated power control table. If a level adjustment is effected before the correlation detection such as an AGC circuit or the like in the reception system, the reception power calculation circuit  102  calculates the reception power in accordance with an AGC gain in addition to the correlation detection output  101 . The sc bit is detected from a demodulation result. 
     FIG. 2 is a graphical drawing showing the power control table in the transmission power determining circuit  104  shown in FIG.  1 . When the sc bit is indicative of decreasing the transmission power, the compensation circuit  106  compensates the power control table  201  in a decreasing direction and thus, a compensated power control table  202  is obtained with the transmission power decreased over a whole range of the reception power. An amount of the compensation in response to one pulse of the sc bit is determined by data in the sc bit or alternatively, it is determined data stored in the compensation circuit  106 . 
     FIG. 3 is a block diagram of a communication apparatus of the first embodiment including the transmission power control portion, which is also referred to in the second and third embodiments. The communication apparatus of the first embodiment, as a mobile unit, comprises an antenna  301 , a duplexer  302 , a receiving portion  320 , the transmission power control circuit  310 , and a transmission portion  321 . 
     The antenna  301  receives a first CDMA radio wave signal  317  including the sc bit and transmits a second CDMA radio wave signal  316 . The duplexer  302  duplexes the received first CDMA radio wave signal with the second CDMA radio wave signal. The receiving portion  320  includes an AGC circuit  303  for amplifying the received first CDMA radio wave signal with a gain controlled and supplying data of the gain to the transmission power control circuit  310 , a PN (pseudo noise) code generator  304  generating a PN code; a correlation detection circuit  305  detects a correlation between the first CDMA radio wave signal from the AGC circuit  303  and the PN code from the PN code generator  304  and outputs a correlation result as a desired wave  101 ; a demodulation circuit  307  demodulates the correlation result  101  and outputs a demodulation data  308  including the sc bit, and a sc bit detector  309  for detecting and supplying the sc bit from the demodulation data  308  to the transmission power control circuit  310 . 
     The transmission portion  321  includes a PN code generator  313  for generating a second PN code, a spectrum spreading circuit for spectrum-spreading transmission data with the second PN code, and a power amplifier  315  for amplifying the output of the spectrum spreading circuit  314  with the transmission power controlled in accordance with the transmission power setting value from the transmission power control circuit  310 . The amplified transmission data is supplied to the duplexer  302  and transmitted by the antenna  301  as the second CDMA radio wave signal  317 . 
     The AGC circuit  303  amplifies the received first CDMA radio wave signal with the gain controlled to have a constant intensity and supplies the data of the gain, i.e., AGC gain data, to the transmission power control circuit  310 . The PN code generator  304  generates the PN code assigned to this communication apparatus. The correlation detection circuit  305  detects the correlation between the first CDMA radio wave signal from the AGC circuit  303  and the PN code from the PN code generator  304  to effect an inverse-spectrum-spreading and outputs the correlation result as a desired wave component. The demodulation circuit  307  demodulates the correlation result, effects a carrier removing processing, an error correction processing and outputs the demodulation data  308  including the sc bit. The sc bit detector  309  detects the sc bit periodically transmitted. The sc bit  105  is included in a data frame at a predetermined position of the data frame and supplies the sc bit  105  to the transmission power control circuit  310 . 
     Regarding the compensation, it is sufficient that the compensation of the power control table  201  in response to the sc bit  105  is effected to trace a variation due to a temperature characteristic, a traffic variation or the like. Therefore, it is clear that a control cycle by the sc bit  105  (hereinafter referred to as sc bit cycle) T 1  is considerably longer than a controlling cycle T 2  of transmission power controlling provided for the fading variation in accordance with the reception power (T 1 &gt;T 2 ). Therefore, the sc bit is transmitted in a low speed accompanied channel (SACCH). In other words, the controlling cycle T 1  is longer than a transmission cycle of the conventional closed loop controlling. 
     As mentioned, in the communication apparatus of the first embodiment, the transmission power is controlled for the fading variation in accordance with the calculated reception power through a power control table as an open loop controlling. In addition, the power control table is compensated for the traffic variation in accordance with the control signal, that is, the sc bit periodically transmitted from the base station, wherein the controlling cycle T 1  of the transmission power controlling by the sc bit is longer that the controlling cycle of the calculated reception power. 
     A Second Embodiment 
     FIG. 4 is a block diagram of a transmission power control circuit  410  of a second embodiment and a communication apparatus  400  of the third is shown in FIG.  6 . FIG. 5 is a graphical drawing illustrating compensation of the transmission power control table in the second embodiment. A communication apparatus  400  of a second embodiment has substantially the same structure and operation as that of the first embodiment. The difference is that a reception power storing circuit  406  and a compensation range determining circuit  407  are further provided and the compensation circuit  408  compensates the power control table in the transmission power determining circuit  104  with a compensation range controlled. 
     The reception power calculation circuit  102  calculates a reception power of a desired wave component at an antenna. A calculated reception power is supplied to a transmission power determining circuit  104 . The transmission power determining circuit  104  determines a transmission power setting value  405  from the calculated reception power in accordance with an initial setting value from an initial setting value storing circuit  103  through a power control table included therein in a power on condition or a reset-start condition. During communication, i.e., in a normal condition, a compensation circuit  408  compensates the power control table stored in the transmission power determining circuit  104  in accordance with the sc bit indicative of compensating the transmission power table which represents a relation between a reception power and a transmission power. The transmission power determining circuit  104  determines the transmission power setting value  405  in accordance with the calculated reception power through the compensated power control table. If a level adjustment is effected before the correlation detection such as an AGC circuit or the like in the reception system, the reception power calculation circuit  102  calculates the reception power in accordance with an AGC gain in addition to the correlation detection output  101 . 
     The reception power calculation circuit  102  calculates the reception power of the desired wave component at the antenna  301 . A calculated reception power is supplied to a transmission power determining circuit  104 . The transmission power determining circuit  104  determines a transmission power setting value  405  from the calculated reception power in accordance with the initial setting value from the initial setting value storing circuit  103  through the power control table  201  included therein in the power on condition or the reset-start condition. During communication, the reception power is stored in the reception power storing circuit  406  with a sampling interval. The compensation range determining circuit  407  obtains a reception power distribution  501  from the stored reception power storing circuit  406  as shown in FIG.  5 . The compensation range determining circuit  407  analyzes the reception power distribution  501  or  504  and determines sections  509  of which frequencies (the number of times per a predetermined interval) of the occurrences of reception power values at respective sections are relatively high. If the variation due to a fading is slow, the reception power distribution  501  is provided. Then, the compensation range determining circuit  407  determines the compensation range  507  from the sections  509  where the frequencies are high. The compensation circuit  408  compensates the power control table with transmission power values in the compensation range  507  in response to the sc bit  105 . The transmission power determining circuit  104  determines the transmission power setting value  405  in accordance with the compensated power control table  503 . The amplifier  315  amplifies the spectrum-spread transmission data with the transmission power controlled with the transmission setting value  405  from the transmission power control circuit  410 . 
     If the variation due to a fading is fast, the reception power distribution  504  is provided, wherein the variation due to fading occurs over the whole reception power range. Then, the compensation range determining circuit  407  determines the compensation range  508  wherein there is no section where the frequency of reception power value is relatively higher than other sections. The compensation circuit  408  compensates the power control table with transmission power values in the compensation range  508  compensated in response to the sc bit  105 . The transmission power determining circuit  104  determines the transmission power setting value in accordance with the compensated power control table  506 . The amplifier  315  amplifies the spectrum-spread transmission data while the transmission power is controlled with the transmission setting value  405  from the transmission power control circuit  410 . 
     As mentioned, the communication apparatus of the second embodiment controls the transmission power in accordance with the distribution of sampled and stored reception power through analyzing to adaptively control the transmission power in accordance with a variation speed due to fading in addition to the controlling according to the first embodiment. A period for obtaining the reception power distribution may agree or disagree with a period for determining the sc bit in the base station. 
     Third Embodiment 
     FIG. 6 is a block diagram of a transmission power control circuit  610  of a third embodiment and a communication apparatus  600  of the third embodiment is also shown in FIG.  6 . The communication apparatus  600  of the third embodiment has substantially the same structure and operation as that of the second embodiment. The difference is that the compensation circuit  608  receives a compensation allowable range data and compensates the power control table within the compensation allowable range indicated by the compensation allowable range data. 
     The reception power calculation circuit  102  calculates a reception power of the desired wave component at the antenna  301 . The calculated reception power is supplied to a transmission power determining circuit  104 . The transmission power determining circuit  104  determines a transmission power setting value  605  from the calculated reception power in accordance with the initial setting value from the initial setting value storing circuit  103  through the power control table included therein in the power on condition or the reset-start condition. During communication, the compensation circuit  608  compensates the power control table stored in the transmission power determining circuit  104  in accordance with the sc bit indicative of compensating the transmission power table within the compensation allowable range of the transmission power in accordance with the compensation allowable range data  610 . 
     FIG. 7 is a graphical drawing illustrating compensation of the transmission power control table in the third embodiment, wherein transmission power values are partially and repeatedly compensated in response to sc bits, wherein at a section A, the transmission power values reach an upper limit of the compensation allowable range. Therefore, the transmission power value at the section A is not changed further. At other sections, the transmission power values can be compensated. 
     According to this embodiment, the transmission power controlling is effected with the compensation allowable range. Then, it is prevented that all communication apparatus enter a divergent condition by that all communication apparatus compensate the power control tables in the increasing direction successively. 
     The compensation allowable range is provided with only upper limit, only lower limit, or upper and lower limits. 
     Fourth Embodiment 
     FIG. 8 is a block diagram of a transmission power control signal generation portion  1009  of a fourth embodiment and FIG. 10 is a block diagram of a communication apparatus  1000  of the fourth embodiment, which is also referred to in later embodiments. 
     The transmission power control signal generation circuit  1009  comprises a reception power calculation circuit  802  for calculating a reception power of a desired wave component at an antenna  1001  in consideration of an AGC gain data; a reception power storing circuit  803  for storing the calculated reception power values; an averaging circuit  804  for averaging the calculated reception power values; a comparing circuit  805  for comparing the averaged reception power value with a target level value  806 , wherein the comparing circuit  805  obtains an error from the difference between the averaged reception power value and the target level value  806 ; and an sc bit judging circuit  807  for judging whether the error exceeds a predetermined value and generating the sc bit  808  if the error exceeds the predetermined value. 
     The reception power calculation circuit  802  periodically calculates the reception power of a desired wave component at the antenna  1001 . The calculated reception power is stored in the reception power storing circuit  803 . The averaging circuit  804  averages the calculated reception power values from the reception power storing circuit  803 . The comparing circuit  805  compares the averaged reception power value with the target level value  806  and obtains the error from the difference between the averaged reception power value and the target level value  806 . The error is supplied to the sc bit judging circuit  807  as a transmission power setting error. The sc bit judging circuit  807  judges whether the transmission power setting error exceeds the predetermined value and generates the sc bit  808  if the error exceeds the predetermined value. 
     FIG. 9 is a graphical drawing of the fourth embodiment illustrating obtaining the error  904  between the target level  806  and the averaged reception power value  902 . In this embodiment, the error is determined from the averaged reception power value. However, it is also possible to provide the error from a center value or a reception power value having a higher possibility from the reception power level distribution  901 . The amount of the correction is determined by a variance of the reception power level distribution  901  and is transmitted in the sc bit. 
     If a level adjustment is effected before the reception power calculation such as an AGC circuit or the like in the reception system, the reception power calculation circuit  802  calculates the reception power in accordance with an AGC gain in addition to the correlation detection output  801 . 
     The communication apparatus  1000  of the fourth embodiment, as a base station, comprises an antenna  1001 , a duplexer  1002 , a receiving portion  1020 , the transmission power control signal generation circuit  1009  for generating a transmission power control signal, as the sc bit, and a transmission portion  1021 . 
     The antenna  1001  transmits the first CDMA radio wave signal and receives the second CDMA radio wave signal from a mobile unit. The duplexer  1002  duplexes the received second CDMA radio wave signal with the first CDMA radio wave signal. The receiving portion  1020  includes an AGC circuit  1003  for amplifying the received second CDMA radio wave signal with a gain controlled and supplies data of the gain, i.e., AGC gain data, to the transmission power control signal generation circuit  1009 , a PN code generator  1004  for generating a PN code; a correlation detection circuit  1005  for detecting a correlation between the second CDMA radio wave signal from the AGC circuit  1003  and the PN signal from the PN code generator  1004  and outputting a correlation result of the desired wave, and a demodulation circuit  1007  for demodulating the correlation result and outputting a demodulation data  1008 . 
     The transmission portion  1021  comprises a multiplexer  1014  for multiplexing data to be transmitted with the sc bit to output a multiplexed transmission data, a PN code generator  1015  for generating a PN code, a spectrum spreading circuit  1016  for spectrum-spreading the multiplexed transmission data with the PN code from the PN code generator  1015 , and a power amplifier  1017  for amplifying the output of the spectrum spreading circuit  1014  with the transmission power is controlled. The amplified transmission data is supplied to the duplexer  1002  and transmitted by the antenna  1001  as the first CDMA radio wave signal. 
     The AGC circuit  1003  amplifies the received first CDMA radio wave signal with the gain controlled to have a constant intensity and supplies the data of the gain, i.e., the AGC gain data, to the transmission power control circuit  1009 . The PN code generator  1004  generates the PN signal assigned to the mobile unit to be communicated. The correlation detection circuit  1005  detects the correlation between the second CDMA radio wave signal from the AGC circuit  1003  and the PN signal from the PN code generator  1004  to effect inverse-spectrum-spreading and outputs the correlation result of the desired wave component. The demodulation circuit  1007  demodulates the correlation result, that is removes a carrier component and outputs a demodulation output  1007   a . The demodulation circuit  1007  further effects an error correction processing, and outputs the demodulation data  1008  and CRC detection bit  1301 . 
     The transmission power control signal generation circuit  1009  generates the transmission power control signal as the sc bit from the correlation detection output  801  and the AGC gain data. The transmission portion  1021  transmits transmission data including the sc bit  1012  spectrum spread from the antenna  1001 . 
     Fifth Embodiment 
     FIG. 11 is a block diagram of a transmission power control signal generation circuit  1100  of a fifth embodiment and FIG. 10 also shows a communication apparatus of the fifth embodiment. The communication apparatus  1100  of the fifth embodiment has substantially the same structure and operation as those of the fourth embodiment. The difference is that the transmission power control signal generation circuit  1109  is used instead of the transmission power control signal generation circuit  1009 . 
     The transmission power control signal generation circuit  1109  comprises a desired wave power calculation circuit  1102  for calculating a reception power of a desired wave component at the antenna  1001 , an interference power calculation circuit  1104  for calculating a reception power of interference wave components at the antenna  1001 , an SIR operation circuit for operating a signal to interference power ratio (SIR), a comparing circuit  1106  for comparing the signal to interference power ratio with an SIR target level  1107  to output an error in the signal to interference power ratio, an sc bit judging circuit  1108  for judging the error in the signal to interference power ratio, wherein if the error exceeds a predetermined value, the sc bit judging circuit  1108  outputs the sc bit  1110 . 
     The desired wave power calculation circuit  1102  periodically calculates the reception power of a desired wave component at the antenna  1001  from the correlation detection output  801  or a demodulation output which is obtained by the demodulation circuit  1007  by removing a carrier component from the correlation detection output. The interference power calculation circuit  1104  periodically calculates the reception power of interference wave components at the antenna  1001  from the correlation detection output  801  or the demodulation output  1007   a . In these operations, cycles of calculation of reception power of the desired wave component and the interference wave components may be different from each other. 
     The SIR operation circuit  1105  operates the signal to interference power ratio (SIR) from the calculated reception power of the desired wave component and the calculated reception power of the interference wave components. The comparing circuit  1106  compares the signal to interference power ratio with an SIR target level  1107  to obtain the error in the signal to interference power ratio. The sc bit judging circuit  1108  judges the error in the signal to interference power ratio. If the error exceeds a predetermined value, the sc bit judging circuit  1108  outputs the sc bit  1109 . 
     The sc bit is transmitted in the first CDMA signal from the antenna  1001 . 
     FIG. 12 is a graphical drawing of the fifth embodiment illustrating obtaining the error  1204  between the SIR target level  1107  and the averaged SIR  1202 . In this embodiment, the error is determined from the SIR  1202 . However, it is also possible to provide the error from a center value or an SIR having a higher possibility from the SIR distribution  1201 . The amount of the correction is determined by a variance of the SIR distribution  1201  and is transmitted in the sc bit. 
     Sixth Embodiment 
     FIG. 13 is a block diagram of a transmission power control signal generation circuit  1309  of a sixth embodiment and a communication apparatus  1300  of the sixth embodiment is also shown in FIG. 10. A communication apparatus  1300  of the sixth embodiment has substantially the same structure and operation as those of the fourth embodiment. The difference is that the transmission power control signal generation circuit  1309  is used instead the transmission power control signal generation circuit  1009 . 
     The transmission power control signal generation circuit  1309  comprises a frame error rate operation circuit  1302  for operating a frame error rate from error detection information (a CRC detection bit)  1301  from the demodulation circuit  1007 , a comparing circuit  1303  for comparing the frame error rate with a target level  1304  to output an error in the frame error rate, an sc bit judging circuit  1305  for judging the error to output the sc bit  1306 , wherein if the error in the frame error rate exceeds a predetermined value, the sc bit judging circuit  1305  outputs the sc bit  1306 . 
     The demodulation circuit  1007  effects the error correction operation as mentioned above. During this operation the demodulation circuit outputs the error detection information, that is, the CRC detection bit  1301 . 
     The frame error rate operation circuit  1302  operates the frame error rate from the CRC detection bit  1301  from the demodulation circuit  1007 . The comparing circuit  1303  compares the frame error rate with the target level  1304  to output the error in the frame error rate. The sc bit judging circuit  1305  judges the error. If the error in the frame error rate exceeds a predetermined value, the sc bit judging circuit  1305  outputs the sc bit  1306 . 
     Seventh Embodiment 
     FIG. 14 is a block diagram of a communication system of a seventh embodiment. The communication system of the seventh embodiment uses any of the communication apparatus  300 ,  400 , or  600  of the first to third embodiments as the mobile unit  1402  and any of the communication apparatus  1000 ,  1100 , or  1300  of the fourth to sixth embodiments as the base station  1401 . 
     The communication system of the seventh embodiment comprises the communication apparatus  1401  as a base station for transmitting the first CDMA radio wave signal  1403  including the sc bit and receiving the second CDMA radio wave signal  1404  and a plurality of communication stations  1402  as a mobile unit for receiving the first CDMA radio wave signal  1403  and transmitting the second CDMA radio wave signal  1404  with the transmission power controlled in accordance with the detected reception power and the sc bit through the power control table. 
     FIG. 15 shows a timing chart of the communication apparatus of the seventh embodiment. In the base station  1401 , the sc bit is detected every four frames, that is, 40 ms. The transmission data is transmitted every frame of 10 ms and an interleaving processing of 10 ms is effected. The open loop transmission power control in the mobile unit  1402 , that is, the transmission control in accordance with the reception power through the power control table is effected at the cycle T 2 ≦10 ms. 
     In the base station  1401 , the sc bit is judged every 40 ms from the reception signal BSRX at t 1  (t 5 , t 6 ) and the sc bit is transmitted through the first CDMA radio wave signal (BSTX) at a timing t 2  with an interleaving delay of one frame. At a timing t 3 , the mobile unit  1402  receives the first CDMA radio wave signal and the sc bit detector  309  detects the sc bit at a timing t 4  with a de-interleaving delay of one frame developed in demodulating. 
     As mentioned, in the communication system of the seventh embodiment, the mobile unit  1402  compensates the power control table with the control signal (the sc bit) periodically transmitted from the base station  1401 , so that the control error in the open loop controlling of the transmission power control can be compensated. Moreover, the sc bit cycle T 1  determined in consideration of a variation in the temperature characteristic or a traffic variation is relatively longer than the cycle T 2  of the transmission power controlling in accordance with the reception power determined in consideration of fading. Therefore, it is possible to transmit the sc bit in a low speed accompanied channel (SACCH). Therefore, an amount of control signals per a predetermined interval can be reduced, so that a frequency utilizing efficiency can be increased.

Technology Category: 5