JP2005268849A - Diversity receiving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diversity receiving device with a small circuit scale for realizing a low consumed current regardless of permitting a fixed gain difference between antennas contributing to the downsizing of and the degree of design flexibility of the receiver, while fully developing the effect of space diversity reception in the DS-CDMA system. <P>SOLUTION: A digital signal processing section 102 is provided with AGC control sections 11A, 11B for independently controlling both AGC an amplifier section 8 and search finger processing sections 10A, 10B corresponding to branches of RF reception signal processing sections 101A, 101B; a set of a plurality of tracking finger processing sections 9; a path searching and path selecting section 14; and a threshold and correction level generating unit 18. The path search and path selection section 14 applies dynamic path search to each branch, in cooperation with the search finger processing sections 10A, 10B, uses a correction signal from the threshold and correction level generating unit 18, to correct the received signal level thereby carrying out path selection for rake synthesis on the basis of a result of this correction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a diversity receiver that applies space diversity reception to a DS-CDMA system.

  As a third-generation mobile radio communication system, a direct sequence code division multiple access (DS-CDMA) system (for example, W-CDMA system), which is one of IMT-2000 radio access systems Is currently being standardized in 3GPP (Third Generation Partnership Project). In Release 5 of 3GPP, the packet transmission function of the DS-CDMA wireless interface described above is expanded to realize a high-speed packet communication method (HSDPA: High Speed Downlink Packet Access) that can realize 14.4 MHz as the maximum data transmission rate. ) Has been specified. In this HSDPA, in order to increase the throughput of packet data, a combination of a data modulation scheme and an error correction coding rate in accordance with a change in reception C / I on the terminal side (defined by CQI: Channel Quality Indicator in 3GPP) (Hereinafter referred to as MCS: Modulation and Coding Scheme), Hybrid ARQ (Hybrid Automatic Repeat reQuest) for reusing previously received packet data when a data retransmission request is made, and efficient radio resource management New technologies such as Fast Resource Allocation by a possible base station (Node-B) are used.

  As a method of optimizing the MCS described above, a higher rate packet data transmission is allocated to a terminal having a good reception state, and a lower rate packet data transmission is limited to a terminal having a poor reception state. As a result, highly efficient transmission can be realized as a whole, and the average throughput of the entire system can be increased. In order to determine the quality of this reception state, reception C / I reported from time to time from the terminal side is used. Here, the reception C / I is a reception SIR (Signal to Interference Ratio) measured on the terminal side.

  FIG. 4 shows an image diagram of the received C / I value on the terminal side and the MCS of the packet data allocated from the base station side. In the figure, numerical values 1 to 3 of “downlink packet data” are respectively high-order modulation & high-order coding rate data, medium-order modulation & medium-order coding rate data, and low-order modulation & low-order coding rate data. Is shown. As can be seen from FIG. 4, “1” is assigned when the terminal-side received C / I value is high, “3” is assigned when the terminal-side received C / I value is low, and “2” is assigned at an intermediate time. Therefore, if the reception SIR value on the terminal side, in other words, the reception quality characteristic in the terminal can be improved, the base station side can allocate a higher rate of packet data transmission to each terminal accordingly. Overall, the average throughput can be increased.

  FIG. 5 shows the timing of each physical channel signal specified by HSDPA. CPICH (Common Pilot CHannel) and P-CCPCH (Primary Common Control Physical CHannel) & SCH (Synchronization CHannel) are used for cell search, channel estimation, and acquisition of broadcast information from a cell. On the other hand, HS-SCCH (High Speed Shared Control CHannel) and HS-PDSCH (High Speed Physical Downlink Shared CHannel) are downlink physical channel signals used when performing HSDPA, and HS-SCCH is a packet for each terminal. HS-PDSCH is a packet data channel corresponding to the presence / absence of a signal and a control channel for notifying the corresponding MCS.

  The DS-CDMA receiver uses the Rake reception method. The Rake reception method is a reception method in which signal components having a phase difference and a time difference at the time of reception due to radio wave reflection or the like are taken out separately and combined with the same phase and time.

  As a method for improving the reception quality characteristic in the terminal described above, there are techniques such as space diversity reception and multipath interference canceller. In particular, space diversity reception is conventionally known as a method for improving reception quality characteristics against deterioration of reception characteristics due to fading in land mobile communication (see Patent Documents 1 and 2).

In particular, Patent Document 1 discloses a technique combining space diversity reception and Rake reception.
JP 2001-168780 A JP 2003-258663 A

  In a technique combining space diversity reception and Rake reception, when performing common gain control for each antenna branch, a large variation in AGC characteristics in each antenna branch leads to a path selection error in Rake combining, Degradation of reception characteristics is caused. Therefore, variation accuracy of AGC characteristics in each antenna branch is required, and fine adjustment of AGC characteristics is required for each antenna branch.

  Furthermore, in order to make full use of the effect of improving the ideal space diversity characteristics, there is no correlation between the antennas of each antenna branch, and the antenna gain is required to be equal. However, in general, mobile phones of mobile communication systems have a fixed gain difference between the antennas, for example, one antenna is a whip antenna and the other antenna is a built-in antenna because of the downsizing and design of the device. Will definitely occur. For this reason, it is difficult to always expect the effect of improving the characteristics of space diversity reception. In an extreme case, it is equivalent to the case of single branch reception.

  The receiving apparatus described in Patent Document 1 discloses a technique for applying AGC independently for each antenna branch, but each of the antenna, the receiving system RF unit and the A / D converter, the receiving system baseband signal processing unit, etc. Since each antenna branch is prepared, there is a problem that the circuit scale and current consumption increase.

  The present invention solves the above-described problems. When space diversity reception is applied in the DS-CDMA system, the effect of the space diversity reception is fully utilized, and the apparatus can be downsized and the degree of design freedom can be achieved. It is an object of the present invention to provide a diversity receiver that allows a fixed gain difference between contributing antennas, reduces the circuit scale, and realizes low current consumption.

  A diversity receiver according to the present invention is a diversity receiver that applies space diversity reception to a DS-CDMA system, and corresponds to a plurality of antennas corresponding to a plurality of branches of space diversity, and the plurality of antennas, A plurality of RF reception signal processing units including a quadrature demodulation unit, an AGC amplification unit, and an analog / digital converter of the reception signal, and a Rake reception and decoding process upon receiving digital outputs of the plurality of RF reception signal processing units A digital signal processing unit that independently controls the AGC amplification unit of each of the plurality of RF reception signal processing units. The digital signal processing unit performs synchronization acquisition of each path and reception signal level detection for each branch by measuring an average delay profile of each branch, and a plurality of search finger processing units corresponding to the plurality of branches, One set of receiving the outputs of the plurality of received RF signal processing units, synchronously tracking a plurality of paths based on phase information from the plurality of search finger processing units, performing despreading processing, and performing coherent detection In cooperation with the plurality of tracking finger processing units, correction level generating means for generating a correction signal for correcting the reception signal level of the plurality of search finger processing units, and the plurality of search finger processing units, A path search is performed dynamically for the received signal level using the correction signal from the correction level generating means. And a path search & path selection unit for selecting a path for Rake synthesis based on the correction result, and the path selected by the path search & path selection unit for the one set of tracking fingers. A plurality of RAKE combining units that receive the output of the processing unit and that perform RAKE combining; AGC controller, a Rake combiner for combining the outputs of the plurality of tracking finger processors, and a decoding means for decoding the output of the Rake combiner.

  The digital signal processing unit independently controls the AGC amplification unit of each of the plurality of RF reception signal processing units. The correction level generation means generates a correction signal for correcting the reception signal level of the plurality of search finger processing units. A path search & path selection unit cooperates with the plurality of search finger processing units to dynamically perform a path search for each branch, and to correct the received signal level using a correction signal from the correction level generation means. Based on the correction result, a path selection for Rake synthesis is performed. As a result, the received signal level can be corrected corresponding to the branch, so that even if there is an average gain difference between the branches, the desired reception path can be appropriately selected.

  The correction level generation means determines that the necessity for correction is low when the average gain difference is equal to or less than the threshold by performing threshold determination on the average gain difference between the branches. Thus, it is possible not to output the correction signal of the received signal level.

  In an embodiment of the present invention, the digital signal processing unit includes a gain setting value in the plurality of AGC control units and a value obtained by integrating averaged delay profiles of the plurality of search finger processing units within a path search range, respectively. By using, a reception electric field strength measuring unit for measuring the electric field strength of the reception signal in each branch is provided. The received electric field strength measuring unit can average the electric field strength of the received signal in each branch within a predetermined time, and dynamically calculate the difference in average gain between the branches. As a result, it becomes possible to appropriately cope with changes in the reception environment.

  The path search & path selection unit may dynamically set a path search range for each of the search finger processing units. This makes it possible to follow a delay profile that fluctuates at high speed in a land mobile communication environment.

  The digital signal processing unit includes a correction determination signal generator that generates a correction determination signal based on a signal from the AGC control unit, and corresponds to each branch in the path search & path selection unit using the correction determination signal. The correction of the received signal level of the search finger processing unit is suppressed. The correction determination signal generator generates the correction determination signal by, for example, determining the electric field strength of the received signal that is predominantly influenced by thermal noise based on gain in AGC control by the plurality of AGC control units. can do. This utilizes the fact that the gain in AGC control and the electric field strength of the received signal have a one-to-one correspondence. As a result, erroneous correction of the received signal level can be prevented.

  The digital signal processing unit determines that the difference in average gain difference between the branches is large and does not contribute to Rake reception based on the signal from the reception field strength measurement unit and / or the signal from the correction level generation unit. In this case, an intermittent power supply control unit that temporarily turns off the power of the RF reception signal processing unit, the AGC control unit, and the search finger processing unit related to the branch determined not to contribute may be provided. Thereby, useless power consumption can be reduced. The intermittent power control unit may dynamically change a power-off time for intermittently stopping power supply in accordance with a given signal.

  According to the present invention, when space diversity reception is applied in the DS-CDMA system, it is possible to reduce the size of the apparatus and the degree of design freedom while fully utilizing the effect of space diversity reception, which was difficult in the conventional system. It is possible to sufficiently tolerate a fixed gain difference between the antenna branches that contributes to. In particular, by reducing the circuit scale added to the conventional single receiver, the current consumption can be reduced.

  Furthermore, when the effect of space diversity reception cannot be expected, it is possible to further reduce the current consumption as a whole by temporarily turning off the power of the circuit unit related to the antenna branch. Thereby, the usable time of the apparatus which uses a battery especially can be extended.

  By applying the present invention to a mobile communication terminal, it is possible to realize a terminal that supports high-speed packet data transmission in the DS-CDMA system with a reduced apparatus size, low current consumption, and good reception quality characteristics. .

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  FIG. 1 is a block diagram showing a circuit configuration for applying space diversity reception to a DS-CDMA mobile communication terminal according to the present invention. Here, a case where the number of branches is two is shown.

  In FIG. 1, an antenna 1A is a main antenna for both transmission and reception, and an antenna 1B is a sub-antenna dedicated for reception. For example, one antenna is a whip antenna and the other antenna is a built-in antenna. The high-frequency signal received by the antenna 1A is input to the RF reception signal processing unit 101A after the duplexer (DUP) 2 attenuates unnecessary waves that cause transmission wave leakage, spurious response, blocking, and the like. In the RF reception signal processing unit 101A, an input signal is amplified by a low noise high frequency by a low noise amplifier (LNA) 4 and converted into orthogonal I and Q baseband signals by an orthogonal demodulation unit 5. The I and Q baseband signals are subjected to channel selection by a low-pass filter (LPF) unit 6 and then subjected to AGC amplification by an automatic gain control (AGC) amplification unit 7. At this time, AGC control is performed in the A / D converter 8 so that the received signal can always be quantized with an optimum dynamic range. Subsequently, the I and Q baseband signals converted into digital data by the A / D converter 8 are input to the digital signal processing unit 102.

  On the other hand, the high-frequency signal received by the antenna 1B is input to the RF reception signal processing unit 101B after attenuation of unnecessary waves that cause spurious responses, blocking, and the like in the BPF 3. In the RF reception signal processing unit 101B, signal processing similar to that of the RF reception signal processing unit 101A described above is performed, and then input to the digital signal processing unit 102.

  Here, taking into account the insertion loss of DUP 2 or BPF unit 6 and the NF and gain of RF reception signal processing units 101A and 101B, from the input terminal of antenna 1A to the A / D converter input of RF reception signal processing unit 101A Each stage so that the total NF (Noise Figure) and the total gain are equal between the received signal and the received signal from the input terminal of the antenna 1B to the input of the A / D converter of the RF received signal processing unit 101A. Is a level diagram designed. As a result, the C / Ns of the reception signals of branch A and branch B are equal, and space diversity reception can be performed ideally. The LNA 4 of the RF reception signal processing units 101A and 101B has a function capable of AGC control so as not to be saturated when the reception signal level is a strong input.

  In the digital signal processing unit 102, control of the AGC amplification unit 7, Rake reception, and decoding processing are performed. Specifically, the digital signal processing unit 102 includes a number of search finger processing units 10 (10A and 10B) and AGC control units 11 (11A) corresponding to the number of space branches (two in this case) of the branches A and B, respectively. , 11B). However, each signal processing unit such as the tracking finger processing unit 9, the path search & path selection unit 14, the Rake combining unit 15 and the like has only one like the single branch receiver. Therefore, the circuit scale and current consumption can be reduced.

  The search finger processing units 10A and 10B measure the average delay profile of each branch and perform synchronization acquisition of each path and reception signal level detection corresponding to the branch. The tracking finger processing unit 9 synchronously follows a plurality of paths based on the phase information from the search finger processing units 10A and 10B, performs despreading processing, and performs coherent detection. The path search & path selection unit 14 cooperates with the plurality of search finger processing units 10A and 10B to perform path search dynamically for each branch in time series, and to select a path for Rake synthesis. The Rake combining unit 15 performs Rake combining on the path selected by the path search & path selecting unit 14. The output of the Rake combining unit 15 is output to the decoding unit 16 and the SIR estimation unit 17.

  In this embodiment, compared to the case where two sets of tracking finger processing units are used as in the prior art, one set of tracking finger processing units # 1 to #N is shared by branches A and B. Therefore, a maximum of N paths (regardless of which branch) selected by the path search & path selection unit 14 based on the processing result of the search finger processing unit 10 are allocated to the tracking finger processing units # 1 to #N. It is done. Digital data output from the A / D converter 8 is stored in a buffer memory (not shown) for a predetermined amount (for example, several frames), and the tracking finger processing unit 9 includes a search finger processing unit 10 and a path search & path selection. The same data can be processed according to the processing result of the unit 14. Thus, since one set of N tracking finger processing units is flexibly assigned to the selected path, it is not necessary to prepare N tracking finger processing units for each branch as in the prior art.

  Note that the RF reception signal processing units 101A and 101B in FIG. 1 are shown as a direct conversion reception configuration, but a conventional superheterodyne reception configuration may be used.

  As described above, in a mobile terminal of a mobile communication system, usually, one antenna is a main antenna such as a whip antenna, and the other antenna is a sub-antenna such as a built-in antenna. Optimize. Therefore, some fixed gain difference is generated between the main and sub antennas. Therefore, when common equal gain control is performed for each space branch, the average delay profile in the search finger processing unit reflects the fixed gain difference between the two antennas as they are. In general, the path search & path selection unit performs threshold determination on the level of the received signal, and selects a path for Rake combining in descending order of level.

  FIG. 2 shows an example of an averaged delay profile in the search finger processing unit when the influence of thermal noise can be ignored when there is a fixed gain difference between antennas in the conventional method. In this figure, the autocorrelation peak of the desired reception path at each chip timing is indicated by ◯, the cross-correlation peak due to multipath or other cell interference is indicated by ×, and components due to thermal noise are excluded for convenience. In a configuration in which equal gain control common to both branches is performed, when a path is selected in descending order without considering the antenna gain difference between branches A and B, the desired reception path on the branch B side is not selected. On the contrary, the other user interference on the branch A side is selected, and the SIR of the Rake combined received signal is deteriorated.

  On the other hand, in the present invention, in the RF reception signal processing units 101A and 101B in FIG. 1, the reception signals from the two antennas are received by both A / D converters 8 by the AGC control units 11A and 11B corresponding to the respective antenna branches. Since AGC control is performed so that quantization is always performed with an optimum dynamic range, it is not easily affected by the antenna gain difference between branches as in the conventional example described above. However, since the influence of the average gain difference between the two branches remains on the signal level detected by the search finger processing units 10A and 10B even by AGC control independent of each branch, the signal level can be adjusted as necessary as will be described later. Make corrections.

  Further, as described above, in the present invention, in order to reduce the circuit scale, the tracking finger processing unit 9 and the path search & path selection unit 14 are configured as a single unit like the single branch receiver. For this reason, as described above, the path search & path selection unit 14 cooperates with the plurality of search finger processing units 10A and 10B to dynamically perform path search for each branch. The received signal level is corrected using the correction signal from the threshold & correction level generator 18, and a path selection for Rake synthesis is performed based on the correction result. Specifically, the threshold value & correction level generator 18 determines whether or not level correction is performed based on a predetermined threshold value for the average gain difference between the two branches. Further, based on the determination result, the path search & path selection unit 14 is urged to perform path selection by correcting the received signal level of the search finger processing units 10A and 10B corresponding to each branch to a predetermined level. That is, the threshold & correction level generator 18 performs level correction of the received signal level in the search finger processing units 10A and 10B when the average gain difference between the two branches is larger than the predetermined threshold. When the average gain difference is smaller than the predetermined threshold value, it is determined that the correction effect is small and there is no need to perform correction, and level correction is not instructed. As a level correction method, for example, the signal level of the branch with the lower gain is increased by a predetermined amount corresponding to the gain difference. A method for measuring the average gain difference between the branches will be described later.

  By performing the operation described above, the effect of space diversity reception can be sufficiently obtained even when there is a fixed gain difference between the antennas. The parameters of the predetermined threshold value and the correction level value corresponding to the average gain difference between the two branches are optimum values that can accurately select a path from simulation values and experimental results in an actual land mobile communication environment. Shall be determined by choosing

  Next, consider the case where the electric field strength of the received signal is low. FIG. 3 shows an example of an averaged delay profile in the search finger processing units 10A and 10B when the influence of thermal noise is dominant when there is a fixed gain difference between antennas. In this figure, the autocorrelation peak of the desired reception path at each chip timing is indicated by ○, and the thermal noise component is indicated by ×, and for the sake of convenience, components due to multipath and other cell interference are excluded. Since the noise floor level in this case is determined by the NF of the receiver, the reception signal of the branch B is buried in the noise floor depending on the value of the gain difference between the antennas. In other words, when the influence of the thermal noise is dominant, if the received signal level is corrected as described above, there is a higher possibility of erroneous path selection than when no correction is performed.

  On the other hand, when the electric field strength of the reception signal is low, the gain of the AGC amplification unit 7 in the RF reception signal processing units 101A and 101B is controlled to be high by the AGC control in the AGC control units 11A and 11B.

  In the present invention, the correction determination signal generation is performed using the AGC control signals 11sa and 11sb set by the AGC control units 11A and 11B, utilizing the fact that the received electric field strength and the gain of the AGC control correspond one-to-one. The level correction determination signal 13s is generated by setting in advance the electric field strength of the received signal in which the influence of thermal noise is dominant in the device 13. Using this level correction determination signal 13s, the path search & path selection unit 14 determines whether or not the received signal level of the search finger processing units 10A and 10B corresponding to each branch is corrected, and the influence of thermal noise is affected. In the dominant case, correction of the received signal level is not performed, that is, correction of the received signal level of the search finger processing units 10A and 10B is suppressed.

  By such an operation, the path search & path selection unit 14 described above occurs when the influence of thermal noise is dominant when performing path selection after performing level correction corresponding to the average gain difference between antenna branches. It is possible to prevent deterioration of reception characteristics due to a path selection error.

  Note that the electric field strength of the received signal, where the influence of thermal noise is dominant, is almost determined from the reception level diagram design of the mobile wireless terminal, but because there are individual differences in production, it can be adjusted arbitrarily so that it can be adjusted individually. This can be done by providing functions that can be set.

  Next, a method for deriving a fixed gain difference between the antenna branches used for correcting the reception signal level described above will be described.

  In general, the fixed gain difference between each antenna branch varies greatly due to the influence of the chassis, the human body, and the land mobile communication environment during actual use, in addition to the performance difference of the antenna itself. . Therefore, the method of writing a fixed gain difference in the ROM in advance at the time of production of the portable wireless terminal does not reflect the gain difference between the antenna branches in the actual use environment.

  In the present invention, the received electric field strength measuring unit 19 includes the gain setting values of the AGC control units 11A and 11B corresponding to the respective antenna branches and the averaged delay profiles of the corresponding search finger processing units 10A and 10B within the path search range. Is used to measure the electric field strength of the received signal at each antenna branch.

  Although the AGC control period corresponding to each antenna branch depends on the number of bits of the A / D converter, it is usually not the instantaneous value fluctuation due to Rayleigh fading, but the short-term median fluctuation and distance fluctuation due to shadowing are corrected. To work. Therefore, the path search & path selection unit 14 allows the search finger processing units 10A and 10B corresponding to each antenna branch to dynamically set the path search range, thereby changing at high speed in the land mobile communication environment. It becomes possible to follow the delay profile.

  Further, the received electric field strength measuring unit 19 averages the electric field strength of the received signal measured by the above-described method within a predetermined time (for example, a time corresponding to several to several tens of radio frames), so that each antenna The difference in average gain between branches can be calculated dynamically. Thereby, it is possible to appropriately cope with a change in the reception environment.

  With reference to FIG. 6, a mechanism for measuring the electric field strength of the received signal in each antenna branch in the present embodiment will be described. The averaged delay profile in the search finger processing units 10A and 10B includes a desired reception path, thermal noise, and cross-correlation levels of multipath & other cell interference. Therefore, by integrating these reception levels in the path search interval, a value proportional to the electric field strength of the total received signal received by each antenna branch can be obtained. Further, as described above, since the reception electric field strength and the gain of AGC control have a one-to-one correspondence, it is possible to estimate the reception electric field strength of each antenna branch at a certain time by using the information together. Is possible. That is, the gain of AGC control is always the optimum dynamic at the input of the A / D converter, regardless of the difference between VGA (Voltage Gain Amplifier) and PGA (Programmable Gain Amplifier). Since it operates so as to be a level that can be quantized in the range (this is referred to as a target level), the gain value of AGC control set at that time is the desired received signal + thermal noise + other interference signal at the antenna end. There is a one-to-one correspondence to the received field strength. Therefore, by adding the gain value of AGC control and the integrated reception level value and adding an inherent offset value (± α) in the system, the received electric field intensity received at the antenna end can be reduced to some extent. Can be estimated with accuracy.

  As described above, in the present invention, the level diagram is designed so that the total NF and total gain of the received signal from the antenna input terminal to the A / D converter input of the RF received signal processing unit in each antenna branch are equal. Therefore, by providing the above-described function, it becomes possible to adaptively derive a fixed gain difference between the antenna branches in accordance with a change in the actual surrounding environment.

  Furthermore, in the present invention, based on at least one of the difference in average gain between the antenna branches calculated by the reception field strength measurement unit 19 described above and the correction level value generated by the threshold value & correction level generator 18, When the intermittent power supply control unit 12 determines that the average gain difference between the antenna branches is large and the level correction value is large and the influence of the path selection error is larger, the RF related to the antenna branch is determined. The reception signal processing units 101A and 101B, the AGC control units 11A and 11B, and the search finger processing units 10A and 10B have a function of temporarily turning off the power (sleep mode).

  As mentioned above, if the average gain difference between each antenna branch is too large due to the influence of the human body during actual use and the influence of the land mobile communication environment, the space diversity effect from that antenna branch can hardly be expected, By forcibly correcting the level, the reception characteristics are deteriorated due to a path selection error. Therefore, when the average gain difference between the antenna branches is equal to or greater than a predetermined value and / or when the level correction value is equal to or greater than the predetermined value, the RF reception signal processing unit, AGC control unit, and search finger processing related to the antenna branch By turning off the power of the unit, it is possible to reduce wasteful current consumption.

  As shown in FIG. 5, the data length of HS-SCCH and HS-PDSCH is 2 ms (for 3 slots). That is, the rise time and fall time when the power is turned on and off need to be sufficiently shorter than the data length of the signal. On the other hand, the rise / fall time from the sleep mode of the power supply of a general RF reception signal processing unit is within about several tens of μs, and is completed within about several hundreds of μs even if calibration time is added. Since one time slot is about 667 μs, the above-described conditions can be sufficiently satisfied.

  On the other hand, the standby time for determining the specifications of the terminal is calculated on the assumption of an estimate under a certain condition. For example, consider the case where the intermittent reception cycle is 2.56 s. It is also conceivable that the land mobile communication environment during actual use changes during this intermittent reception cycle. However, as described above, in the present invention, the electric field strength of the received signal is averaged within a predetermined time, and by setting an optimal moving average period at the time of intermittent reception, the average gain between each antenna branch is set. The difference can be calculated sufficiently dynamically. In other words, by using the above-described function even during intermittent reception, if it is determined that the difference in average gain difference between each antenna branch is large and does not contribute to Rake reception, RF reception related to that antenna branch is performed. By turning off the power on one side of the signal processing units 101A and 101B, the AGC control units 11A and 11B, and the search finger processing units 10A and 10B, useless current consumption can be reduced.

  The power-off time can be arbitrarily set, and the power-off time may be dynamically changed following a delay profile that fluctuates at high speed in a land mobile communication environment. As a result, it is possible to appropriately reduce the current consumption according to the situation without impairing the original space diversity reception effect.

  The preferred embodiments of the present invention have been described above, but various modifications and changes other than those mentioned above can be made.

It is a block diagram which shows the structure of the circuit which applies space diversity reception to the DS-CDMA system mobile communication terminal in this invention. It is a figure which shows the example of the average delay profile in a search finger process part when the influence of a thermal noise can be disregarded when there exists a fixed gain difference between antennas by the system of a prior art example. It is a figure which shows the example of the average delay profile in a search finger process part when the influence of a thermal noise is dominant when there exists a fixed gain difference between antennas. It is an image figure of MCS of the received C / I value on the terminal side and packet data allocated from the base station side. It is a figure which shows the timing of each physical channel signal specified by HSDPA. It is a figure for demonstrating the mechanism which measures the electric field strength of the received signal in each antenna branch in this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A ... Antenna, 1B ... Antenna, 4 ... Low noise amplifier (LNA), 5 ... Quadrature demodulation part, 6 ... Low-pass filter (LPF), 7 ... Automatic gain control part (AGC), 8 ... A / D converter , 9 ... Tracking finger processing unit, 10, 10A, 10B ... Search finger processing unit, 11, 11A, 11B ... AGC control unit, 12 ... Intermittent power supply control unit, 13 ... Correction determination signal generator, 14 ... Path search & path Selection unit, 15 ... Rake combining unit, 16 ... decoding unit, 17 ... SIR estimation unit, 18 ... threshold & correction level generator, 19 ... received electric field strength measuring unit, 102 ... digital signal processing unit, 101A, 101B ... Received signal processor

Claims (9)

A diversity receiver that applies space diversity reception to a DS-CDMA system,
Multiple antennas corresponding to multiple branches of space diversity;
Corresponding to the plurality of antennas, respectively, a plurality of RF reception signal processing units including a reception signal orthogonal demodulation unit, an AGC amplification unit, and an analog-digital converter;
A digital signal processing unit that receives a digital output of the plurality of RF reception signal processing units, performs Rake reception and decoding processing, and independently controls each AGC amplification unit of the plurality of RF reception signal processing units; ,
The digital signal processor is
A plurality of search finger processing units corresponding to the plurality of branches, performing synchronization acquisition and reception signal level detection for each path by measuring an average delay profile of each branch,
One set of receiving the outputs of the plurality of RF reception signal processing units, synchronously tracking a plurality of paths based on phase information from the plurality of search finger processing units, performing despreading processing, and performing coherent detection A plurality of tracking finger processing units;
Correction level generation means for generating a correction signal for correcting the reception signal level of the plurality of search finger processing units;
In cooperation with the plurality of search finger processing units, a path search is dynamically performed for each branch, and the received signal level is corrected using a correction signal from the correction level generation means. Based on the correction result, A path search & path selection unit that performs path selection for Rake synthesis;
A Rake combining unit that receives the outputs of the one set of tracking finger processing units and performs a Rake combining on the path selected by the path search & path selecting unit;
A plurality of AGC control units corresponding to the plurality of branches, wherein the input level to each analog-digital converter of the plurality of RF reception signal processing units is an optimum input level;
A Rake combining unit that combines the outputs of the plurality of tracking finger processing units with Rake;
Diversity receiving apparatus, comprising: decoding means for decoding the output of the Rake combining unit.   The correction level generation means determines a threshold value for an average gain difference between the branches, and determines whether to output a correction signal of the received signal level based on the threshold value determination. The diversity receiver according to claim 1.   The digital signal processing unit uses a gain setting value in the plurality of AGC control units and a value obtained by integrating averaged delay profiles of the plurality of search finger processing units in a path search range, so that each branch The diversity receiving apparatus according to claim 1, further comprising a received field strength measuring unit that measures a field strength of the received signal.   4. The diversity according to claim 3, wherein the reception electric field strength measurement unit averages the electric field strength of the reception signal in each branch within a predetermined time and dynamically calculates a difference in average gain between the branches. Receiver device.   2. The diversity receiving apparatus according to claim 1, wherein the path search & path selection unit can dynamically set a path search range for each search finger processing unit.   The digital signal processing unit includes a correction determination signal generator that generates a correction determination signal based on a signal from the AGC control unit, and corresponds to each branch in the path search & path selection unit using the correction determination signal. 3. The diversity receiving apparatus according to claim 1, wherein correction of the received signal level of the search finger processing unit is suppressed.   The correction determination signal generator generates the correction determination signal by determining the electric field strength of the received signal in which the influence of thermal noise becomes dominant based on the gain in AGC control by the plurality of AGC control units. The diversity receiver according to claim 6.   When the digital signal processing unit determines that the difference in the average gain difference between the branches is large and does not contribute to Rake reception based on the signal from the reception electric field strength measurement unit and / or the signal from the correction level generation unit And an intermittent power supply control unit for temporarily turning off the power of the RF reception signal processing unit, the AGC control unit, and the search finger processing unit related to the branch determined not to contribute. The diversity receiver according to claim 3.   9. The diversity receiver according to claim 8, wherein the intermittent power supply controller dynamically changes a power-off time for intermittently stopping power supply in accordance with a given signal.

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