JP3688625B2 - Direct spread spectrum communication path search method and receiver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a path search method and a receiving apparatus for multipath finger assignment in a mobile radio system such as a mobile phone system that employs a direct spread spectrum communication system.
[0002]
[Prior art]
The DS-CDMA (Direct Sequence-Code Division Multiple Access) communication system is a system in which a plurality of receivers communicate at the same frequency using different spreading codes. In mobile communication, a multi-wave propagation path (multipath) is formed due to the influence of buildings and topography between a base station and a receiver. In the multi-wave propagation path, waves interfere with each other and cause quality degradation in the receiver. However, in the DS-CDMA system, reception quality can be improved by separating these multi-waves and combining them with RAKE. The process of separating each path from the multiple wave propagation path is a path search. Each path separated by the path search is assigned to each RAKE finger, and a wave of each path is extracted and synthesized. In mobile communication, the state of the multi-wave propagation path, that is, the shape of the delay profile indicating the signal power distribution with respect to the delay time fluctuates with time. Must be assigned to a finger.
[0003]
In general, a delay profile is generated by calculating a correlation power value between a known pilot signal included in a received signal and a spreading code (scramble code) by gradually shifting the delay time. The CDMA receiver is assigned a plurality of path search fingers used for performing path searches in parallel with different delay times, and a plurality of detected paths, and a plurality of paths are used for RAKE combining. RAKE fingers are provided. In the receiver, a delay profile is periodically generated by a path search finger, paths corresponding to the number of RAKE fingers are selected in descending order of power from the delay profile, and each of these paths is assigned to the RAKE finger. .
[0004]
[Problems to be solved by the invention]
In mobile communications, each path of a multiwave propagation path undergoes Rayleigh fluctuation. For this reason, when a delay profile is generated by the path search finger, a large correlation power value may be temporarily obtained or a small correlation power value may be obtained due to the influence of the fluctuation of the multi-wave propagation path. is there. In this case, a path having a large correlation power value is not originally assigned to the RAKE finger, and conversely, a path having a small correlation power value may be erroneously assigned to the RAKE finger. In this case, reception characteristics are deteriorated.
[0005]
On the other hand, since the path allocated to the RAKE finger is updated according to the path search result, there is a possibility that all paths allocated to the RAKE finger may be replaced depending on the result of the measured delay profile. When the allocation path to the RAKE finger is changed, the phase of the code for despreading must be matched with the phase of the new path, so that the processing at the receiver increases and the power consumption increases. There is.
[0006]
In this regard, Japanese Patent Application Laid-Open No. 2000-115022 provides a delay profile power addition unit, averages path fluctuations by fading or the like for the delay profile, and current path allocation states of a plurality of RAKE fingers. The state weighting function is calculated by the above, and the path search is performed after multiplying the state weighting function by the delay profile.
[0007]
However, the averaging of path fluctuations due to fading is expected to have a certain degree of stabilization effect against instantaneous frequency fluctuations, but it is necessary to deal with the instantaneous decrease in received power due to shadowing etc. I can't. Also, in the method of multiplying the delay profile by the state weighting variable calculated based on the current path assignment state of the conventional RAKE finger, the currently assigned path is unconditionally set to a superior level. There is a problem that adaptability to changes in the communication state is reduced.
[0008]
The present invention has been made in view of the above points, and is a direct spread spectrum communication path that can ensure stable reception operation without significantly degrading responsiveness to fluctuations in multiple transmission paths. It is an object to provide a search method and a receiving apparatus.
[0012]
[Means for Solving the Problems]
  According to the present invention1In this path search method, the correlation power value for each delay time between the received direct spread spectrum signal and the spread code is obtained and the current (t_n) And the correlation power value of the current instantaneous delay profile is multiplied by a coefficient α (0 <α <1), and the past (t₁~ T_n-1) Is multiplied by the coefficient (1-α) and the multiplication results are added for each delay time to generate a first new cumulative delay profile. Step and a current (t in each path) with a plurality of RAKE fingers to which each of the plurality of paths is assigned._m) And the current instantaneous correlation power value of each of the obtained paths is multiplied by a coefficient β (0 <β ≦ 1) to obtain the past (t₁~ T_m-1) Multiplying the cumulative correlation power value, which is the entire history of (1), by a coefficient (1-β), and adding the multiplication results for each path to calculate a new cumulative correlation power value for each path; Adding a new cumulative correlation power value for each path to the first new cumulative delay profile for each path to generate a second new cumulative delay profile; and And determining a plurality of paths to be RAKE combined based on a cumulative delay profile.
[0013]
  According to the present invention1The receiving device isThe correlation power value for each delay time between the received direct spread spectrum signal and the spread code is obtained to obtain the current (t _n ) And a path search means for generating an instantaneous delay profile of the past (t ₁ ~ T _n-1 ) And a coefficient α (0 <α <1) for each correlation power value of the current instantaneous delay profile generated by the path search means and a memory having a first storage area for storing a cumulative delay profile that is a history of ), And multiplying each correlation power value of the cumulative delay profile, which is the entire past history stored in the first storage area of the memory, by a coefficient (1-α), and multiplying the result of the multiplication by each delay Cumulative delay profile generating means for adding every time to generate a new cumulative delay profile, and replacing the generated new cumulative delay profile with the cumulative delay profile which is the past all history, the memory A cumulative delay profile updating means for updating the cumulative delay profile stored in the first storage area and a new cumulative delay stored in the first storage area of the memory. Path determining means for determining a plurality of paths to be RAKE-combined based on the profile, and each path of the direct spread spectrum signal and spreading code received by assigning each of the plurality of paths determined by the path determining means A RAKE receiver having a plurality of RAKE fingers for calculating a correlation power value and a RAKE combining means for RAKE combining the correlation power values calculated by these RAKE fingers,The memory comprises a second storage area and a third storage area, and the RAKE receiver has a current (t in each path) with the plurality of RAKE fingers._m) Instantaneous correlation power calculation means for determining the instantaneous correlation power value, and the second storage area of the memory stores the past (t₁~ T_m-1) Is stored, and the cumulative delay profile generation means adds a coefficient β (0 <β ≦ 1) to the instantaneous correlation power value of each path obtained by the instantaneous correlation power calculation means. ), The cumulative correlation power value, which is the entire past history of each path held in the second storage area of the memory, is multiplied by a coefficient (1-β), and the multiplication result is obtained for each path. To calculate the cumulative correlation power value of each new path, and replace the calculated new cumulative correlation power value with the cumulative correlation power value which is the entire past history of each path. The cumulative correlation power value stored in the second storage area is updated, and the cumulative correlation power value stored in the second storage area of the memory is updated for each path in the first storage area of the memory. Is added to the cumulative delay profile stored in A new cumulative delay stored in the third storage area instead of the first storage area of the memory, wherein the path determination means stores the delay profile in the third storage area of the memory. A plurality of paths to be RAKE-combined are determined based on the profile.
[0014]
  First of the present invention1According to the path search method and receiving apparatus ofEach correlation power value of the current instantaneous delay profile is multiplied by a coefficient α, and a coefficient is calculated for each correlation power value of the cumulative delay profile which is the entire past history stored in the first storage means. Multiply (1-α), add these multiplication results for each delay time to create a new cumulative delay profile, and update the cumulative delay profile sequentially. Instantaneous path switching can be prevented even when the path is temporarily lost due to frequency fluctuations or shadowing, etc., and it is possible to respond to the original continuous path change in a relatively short time. . Moreover, since the cumulative delay profile is obtained by accumulating past history information in one delay profile, there is an advantage that a small memory capacity is sufficient as compared with a case where a delay profile for a certain period is stored and averaged. is there. In order to suppress frequent switching of the path and ensure a stable reception state, it is desirable to set the coefficient α to 0 <α <0.5. Further, according to the first path search method and the receiving apparatus of the present invention,UpOfIn addition to the function and effect, the instantaneous correlation power value of each path is obtained by the RAKE finger, and this is multiplied by the coefficient β, and the cumulative correlation power value that is the entire past history of each path stored in the second storage means Is multiplied by a coefficient (1-β), and these multiplication results are added for each path to calculate the cumulative correlation power value of each new path, and the cumulative correlation power value stored in the second storage means Are sequentially updated, and the obtained cumulative correlation power value of each path is added to the cumulative delay profile stored in the first storage means, and this is used as a new cumulative delay profile. That is, in general, the path search is performed in a preset path search cycle, whereas the calculation of the correlation power value in the RAKE finger is executed more frequently than the path search cycle, so that the obtained cumulative delay profile is obtained. Is a reflection of the actual communication state in the RAKE finger. For this reason, by determining a path using this cumulative delay profile, a more stable and adaptive reception operation becomes possible. In addition, since the cumulative correlation power value of each path is obtained by accumulating past history information in one cumulative correlation power value, compared to the case where the correlation power value for a certain period is stored and averaged, There is an advantage that a small memory capacity is sufficient. In order to suppress frequent switching of the path and ensure a stable reception state, it is desirable to set the coefficient β to 0.5 <β ≦ 1.
[0015]
  According to the present invention2The path search method is1In addition to the path search method, a result obtained by multiplying a new cumulative correlation power value of each path by a coefficient γ (γ> 1) is added to the first new cumulative delay profile for each path, A second new cumulative delay profile is generated.
[0016]
  According to the present invention2The receiving device of the above1In addition to the receiving apparatus, the cumulative delay profile generating means multiplies the cumulative correlation power value stored in the second storage area of the memory by a coefficient γ (γ> 1) for each path. It is added to the cumulative delay profile stored in the first storage area of the memory and stored in the third storage area of the memory as a new cumulative delay profile.
[0017]
  First of the present invention2According to the path search method and the receiving apparatus of the present invention, when creating the cumulative delay profile, the weighting specific gravity based on the actual reception state in the RAKE finger is increased. Can be received. The coefficient γ is desirably set to 1 <γ <10.
[0018]
  According to the present invention3The path search method is1And the second2In addition to the path search method, a step of monitoring whether or not the calculated cumulative correlation power value of each new path satisfies a predetermined threshold value, and in this step, the cumulative correlation power value is set to a predetermined threshold value. For a path that is not satisfied, the method further includes the step of deallocating the path from the RAKE finger.
[0019]
  According to the present invention3The receiving device of the above1And the second2In the receiving apparatus, the path determination unit monitors whether the calculated cumulative correlation power value of each new path satisfies a predetermined threshold value, and the cumulative correlation power value satisfies the predetermined threshold value. The path not to be used is characterized in that the path assignment is removed from the RAKE finger.
[0020]
  First of the present invention3According to the path search method and the receiving apparatus, the cumulative correlation power value of each path is monitored, and the allocation of the RAKE finger is removed for a path whose cumulative correlation power value does not satisfy a predetermined threshold. As a result, the reception characteristics can be further improved.
[0021]
The correlation power value of the delay profile and the correlation power value of each path in the RAKE finger may be replaced with a signal power value to interference power ratio obtained by dividing them by the interference power value. Furthermore, reception characteristics are improved.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing a configuration of a receiving apparatus for direct spread spectrum communication according to the first embodiment of the present invention. As shown in FIG. 1, the receiving apparatus includes an antenna 1 that receives a signal, an RF unit 2 that converts a direct spread spectrum signal received via the antenna 1 into a baseband signal, and an RF unit 2 An A / D converter 3 that converts an output from an analog signal to a digital signal, a path search unit 4 that correlates a common pilot signal and a scramble code included in a received signal for path search, and each detected path Stores a RAKE receiver 5 for decoding data and performing RAKE combining, a controller 6 for performing path search control, path determination, path allocation, RAKE reception control, etc., a delay profile for path determination, etc. And a memory 7 to be configured.
[0023]
The path search unit 4 has Pf path search fingers 10. Each path search finger 10 includes a common pilot correlator 11 for synchronous detection of a received signal, a scramble code generator 12 for supplying a scramble code as a spreading code to the common pilot correlator 11, a received signal, 13 are included as power measuring devices for measuring the correlation power with the scramble code. The RAKE receiver 5 includes Rf RAKE fingers 20 and an adder 30 constituting RAKE combining means for combining the signal powers from these RAKE fingers 20 in phase. Each RAKE finger 20 includes a common pilot correlator 21 for synchronous detection of a received signal, a data correlator 22 for demodulating data of each path from the received signal, and a spread code to these correlators 21 and 22. A scramble code generator 23 for supplying a scramble code, and a channelizing code generator 24 for supplying a channelizing code, which is a spreading code, to the data correlator 22 are provided. Each RAKE finger 20 includes a channel response estimator 25 that estimates a channel response based on the correlation value from the common pilot correlator 21, and an estimated channel response and data correlator 22. A complex multiplier 26 that performs complex multiplication of the correlation value and outputs demodulated data, and a delay corresponding to a path assigned to each RAKE finger 20 with respect to the demodulated data output from the complex multiplier 26 A path delay compensation unit 27 that compensates the time and matches the data timing of all the RAKE fingers 20 is provided. In order to perform a path search, a matched filter may be used in place of the correlator 11.
[0024]
Next, the operation of the receiving apparatus configured as described above will be described.
FIG. 2 is a diagram schematically showing the configuration of the received signal. In the received signal, data DATA1, 2, 3,... Spread with different channelizing codes for each user and a common pilot signal that is a known signal are multiplexed. Each base station generates a transmission signal using a scramble code that is different for each base station.
[0025]
In this receiving apparatus, the path search unit 4 and the RAKE receiver 5 operate independently. The path search unit 4 sets the phase of the scramble code generator 12 according to an instruction from the controller 6, and calculates a correlation value with the common pilot signal included in the received signal by the common pilot correlator 11. The correlation power value is measured by the power meter 13 from the correlation value. The power meter 13 averages the correlation results of the common pilot signals over a plurality of symbols, and can be configured by a DSP (Digital Signal Processor) or the like. 3 can be configured. The power meter 13 includes a shift register 131 in which the correlation values from the common pilot correlator 11 are stored for a plurality of symbols, an adder 132 for adding the correlation values stored in the shift register 131, and an adder The multiplier 133 can be configured by squaring the output of 132 to obtain a correlation power value. Thereby, for example, the multipath timing that arrives using 8 symbols of the common pilot signal can be detected in the form of the peak value of the correlation power value.
[0026]
The controller 6 writes the correlation power value calculated by each path search finger 10 in the memory 7. The contents to be written in the memory 7 are correlation power values for each delay time of each path. This is referred to herein as the current “instantaneous delay profile”. For example, as shown in FIG. 4, the plurality of path search fingers 10 calculate the correlation power value of the common pilot signal in parallel by gradually shifting the correlation calculation start timing in the delay time axis τ direction. When paths P1, P2, and P3 are included in the received signal, time t_n-1And time t_nIn the instantaneous delay profile obtained in step 1, peak correlation power values are obtained with delay times corresponding to the head positions of the paths P1, P2, and P3, respectively.
[0027]
On the other hand, in the RAKE receiver 5, each path is assigned to each RAKE finger 20 in accordance with an instruction from the controller 6, and the channelizing code generator 24 and the scramble code generator 23 set the phases of the scramble code and the channelization code, respectively. Then, the despreading process of the received data is executed. At the same time, the transmission path response estimator 25 estimates the transmission path response and applies the result to the data.
[0028]
Next, a path search method according to the first embodiment using the receiving apparatus according to this embodiment will be described.
FIG. 5 is a flowchart of a path search according to the present embodiment realized by the controller 6, and FIG. 6 is a timing chart of the path search. Now, for example, the path search cycle is 50 ms. The controller 6 outputs a search command to the path search unit 4 every 50 ms, fetches the correlation power value from the path search unit 4 at the timing shown in FIG. When the calculation of the correlation power value corresponding to the width of the path search window for generating the delay profile is finished, the writing to the memory 7 is finished. At the next path search time, the controller 6 multiplies each correlation power value of the delay profile written in the memory 7 by a coefficient (1-α) (where 0 <α <1). The contents of the memory 7 are updated (S11). At this time, the delay profile stored in the memory 7 is set to the time (t_nIn order to distinguish it from the “instantaneous delay profile” in FIG. On the other hand, the controller 6 causes the path search unit 4 to calculate the correlation power value corresponding to the width of the path search window, sequentially fetches it, and writes it into the memory 7 as an instantaneous delay profile (S12). At that time, each correlation power value of the instantaneous delay profile is multiplied by a coefficient α (S13). Then, the correlation power for each delay time between the cumulative delay profile (multiplied by the coefficient α) written in the memory 7 and the instantaneous delay profile (multiplied by the coefficient (1−α)). The addition for each value is performed (S14), and the result is written in the memory 7 as a new cumulative delay profile (S15). However, the addition here is addition of paths having the same delay time. A path that satisfies the threshold value and that is equal to or less than the number of RAKE fingers Rf is selected from the information thus updated (S16, 17, 18). The path satisfying the threshold here is, for example, a path having a power peak included within T1 [dB] from the correlation power peak value of the path having the maximum power, or a correlation power value equal to or higher than T2 [dB]. Means a path. As described above, the controller 6 constitutes a cumulative delay profile generation unit, a cumulative delay profile update unit, and a path determination unit.
[0029]
According to the present embodiment, past delay profiles are cumulatively stored in the memory 7, so that it is strong against instantaneous fluctuations, and when the communication condition changes, the instantaneous delay profile Since the cumulative delay profile is sequentially changed, it is possible to follow the changed communication conditions. Further, according to the present embodiment, all cumulative histories (time t₁~ T_n-1Therefore, it is possible to reduce the amount of information to be stored and the number of operation data. Here, α is preferably set to 0 <α <0.5 in order to ensure the stability of communication.
[0030]
(Second Embodiment)
Next, a receiving apparatus for direct spread spectrum communication according to the second embodiment of the present invention will be described. FIG. 7 is a block diagram showing the configuration of the receiving apparatus according to this embodiment. In this embodiment, each RAKE finger 20 ′ of the RAKE receiver 5 ′ is provided with a power measuring device 28 that calculates the correlation power value of each path from the correlation value obtained by the transmission path response estimator 25. The correlation power value from the power measuring device 28 is stored in the memory 7 and used for path determination in the controller 6. Although the transmission path response estimator 25 can be configured by a DSP, in order to further simplify the configuration, for example, as shown in FIG. A shift register 251 in which the correlation values from a plurality of symbols are stored, an adder 252 for adding the correlation values stored in the shift register 251 in vector, and a complex of transmission line responses (complex numbers) obtained by vector averaging It is desirable to include a complex conjugate unit 253 for obtaining the conjugate. Further, as shown in FIG. 8, the power measuring device 28 can be configured by a multiplier 281 that calculates the correlation power value by squaring the vector-averaged transmission path response (complex number). The other configuration is the same as the configuration of FIG. 1, and thus detailed description is omitted.
[0031]
FIG. 9 is a path search flowchart realized by the controller 6 of FIG. 7 according to the second embodiment of the present invention, and FIG. 10 is a timing chart of the path search.
In this embodiment, the memory 7 is logically divided into three storage areas (memory 1, memory 2, memory 3). The operations in the path search unit 4 from step S11 to step S15 in FIG. 9 are basically the same as those in the first embodiment, and thus description of overlapping parts is omitted. The cumulative delay profile is stored in the memory 1.
In the present embodiment, in parallel with the generation and update of the cumulative delay profile in the path search unit 4, the RAKE receiver 5 calculates the correlation power value of each path. FIG. 10 shows the calculation timing. The controller 6 writes the average correlation power value from the transmission path response estimator 25 that estimates the transmission path response, for example, every 10 ms in the memory 2 in parallel with the path search at intervals of 50 ms, for example. When 10 ms elapses, the controller 6 adds a coefficient (1-β) (where 0 <β ≦ 1) to the correlation power value written in the memory 2 (hereinafter referred to as “cumulative correlation power value”). And the contents of the memory 2 are updated (S21). On the other hand, the controller 6 calculates a correlation power value (referred to as “instantaneous correlation power value”) for the path currently allocated to the RAKE receiver 5 (S22), and adds a coefficient β to the obtained instantaneous correlation power value. Multiply (S23). Then, the cumulative correlation power value written in the memory 2 (multiplied by the coefficient (1-β)) and the instantaneous correlation power value (multiplied by the coefficient β) have the same delay time. The contents are added together (S24), and the contents of the memory 2 are updated using the result as a new correlation power value (S25).
[0032]
That is, as shown in FIG. 10, the memory 1 is updated every 50 ms, and the memory 2 is updated every 10 ms. The allocation change to the RAKE finger 20 'is also performed every 50 ms in synchronization with the update of the memory 1. That is, the result obtained by adding the correlation power values of the memory 1 and the memory 2 is written in the memory 3 as a new cumulative delay profile (S26). However, the addition of the memory 1 and the memory 2 is performed between paths having the same delay time. Then, a path that satisfies the threshold value and is equal to or less than the RAKE finger number Rf is selected from the cumulative delay profile in the memory 3 thus generated (S16, S17, S18).
[0033]
According to the second embodiment, the cumulative delay profile is generated using the correlation power value of each path in the RAKE receiver 5 that is calculated more frequently than the path search period. A path search that more reflects the communication status becomes possible. In order to realize a more stable reception operation, β is preferably 0.5 <β ≦ 1.
[0034]
(Third embodiment)
Next, a path search method according to the third embodiment of the present invention will be described.
FIG. 11 is a flowchart of a path search according to this embodiment realized by the controller 6 of FIG. 7, and FIG. 12 is a timing chart of the path search.
Note that the operations of the path search unit 4 and the RAKE receiver 5 'are the same as those in the second embodiment, and therefore the description of the overlapping parts is omitted.
In the present embodiment, when predetermined data is obtained in the memories 1 and 2 through steps S15 and S25, the coefficient γ (> 1) with respect to the cumulative correlation power value of the memory 2 at the timing shown in FIG. Is multiplied by the cumulative delay profile of the memory 1 and the result is written in the memory 3 as a new cumulative delay profile. However, the addition of the memory 1 and the memory 2 is performed between paths having the same delay time. A path satisfying the threshold value is selected from the cumulative delay profile of the memory 3 generated in this way, and a path equal to or less than the RAKE finger number Rf is selected (S16, S17, S18).
[0035]
According to the present embodiment, the correlation power value from the RAKE finger 20 ′ is multiplied by the coefficient γ and then added to the cumulative delay profile in the memory 1 to create a new cumulative delay profile. Therefore, the information from the RAKE finger having higher reliability than the information from the path search finger 10 can be weighted, and the reliability of the receiving operation is improved. As γ, for example, about 1 <γ <10 is desirable.
[0036]
(Fourth embodiment)
Next, a path search method according to the fourth embodiment of the present invention will be described.
FIG. 13 is a flowchart of a path search according to the present embodiment realized by the controller 6 of FIG. 7, and FIG. 14 is a timing chart of the path search.
Note that the operations of the path search unit 4 and the RAKE receiver 5 'and the path determination process are the same as those in the third embodiment, and thus the description of the overlapping parts is omitted.
In the present embodiment, the controller 6 monitors the correlation power value in each RAKE finger 20 every 10 ms that is the update cycle of the memory 2 (S41), and RAKE so as to separate paths that do not satisfy the predetermined threshold T3 [dB]. The receiver 5 is commanded (S42). According to the present embodiment, a path with a poor S / N can be removed from the RAKE finger 20, so that reception characteristics can be further improved.
[0037]
(Fifth embodiment)
In the first embodiment, the correlation power value is used as the data of the instantaneous delay profile and the cumulative delay profile stored in the memory 7, but in the fifth embodiment, signal power versus interference is used instead of these correlation power values. Use power ratio (SIR).
Now, let the path search window width be W and each correlation power value in that range be P (k). However, k = 1, 2,..., W. At this time, the k-th signal power to interference power ratio SIR (k) is obtained by the following calculation.
[0038]
[Expression 1]
SIR (k) = (W−1) × P (k) / (ΣP (j) −P (k))
However, j = 1 to W
[0039]
By replacing the signal-to-interference power ratio SIR thus determined with the correlation power value of the first embodiment, the performance can be further improved.
[0040]
(Sixth, seventh and eighth embodiments)
In the second, third and fourth embodiments, the correlation power value is used as the delay profile data stored in the memory 1 and the data of each path stored in the memory 2, but the sixth, seventh and eighth In the embodiment, the signal power-to-interference power ratio (SIR) obtained in the fifth embodiment is used as the delay profile data stored in the memory 1 instead of the correlation power value, and the RAKE finger 20 stored in the memory 2 is used. The following signal power to interference power ratio (SIR) is used as data from '.
[0041]
For example, when obtaining the signal-to-interference power ratio based on the average correlation power value of the common pilot signal 8 symbols, assuming that each symbol (vector) is V (k), the average vector A is obtained as follows. However, k = 1, 2,...
[0042]
[Expression 2]
A = ΣV (j) / 8
However, j = 1-8
[0043]
If the average power value is Ap,
[0044]
[Equation 3]
Ap = | A |²
[0045]
It becomes. On the other hand, the interference power B is obtained as follows.
[0046]
[Expression 4]
B = (Σ | V (j) −A |²) / 8
However, j = 1-8
[0047]
From the above, the signal power versus the interference power SIRtmp is obtained as follows.
[0048]
[Equation 5]
SIRtmp = Ap / B
[0049]
Furthermore, if the average value of this SIRtmp within 10 ms (18 sets of 8 symbols within 10 ms) is AvSIRtmp,
[0050]
[Formula 6]
AvSIRtmp = ΣSIRtmp / 18
[0051]
By replacing the signal power versus interference power value AvSIRtmp thus determined with the correlation power value from the RAKE finger 20 'in the second, third and fourth embodiments, the performance can be further improved.
[0052]
(Ninth embodiment)
FIG. 15 is a block diagram showing a configuration of a receiving apparatus for direct spread spectrum communication according to the ninth embodiment of the present invention. In the present embodiment, the channel for transmitting data and the channel for transmitting the timing and phase of the system correspond to a system that is transmitted in a time division manner. In this case, there is no common pilot signal, and a pilot signal is embedded in each data.
[0053]
In the receiving apparatus of this embodiment, each path search finger 10 'of the path search receiver 4' is provided with a pilot correlator 14 instead of the common pilot correlator 11 shown in FIG. There is no common pilot correlator 21 in the RAKE finger 20 'that constitutes', and the correlation value from the data correlator 22 is supplied to the transmission line response estimator 25. Since other configurations are the same as those in FIG. 7, description of overlapping portions is omitted.
[0054]
Also in the receiving apparatus according to the present embodiment, the same effects as those of the receiving apparatus in FIG. 7 can be obtained except that the form of the pilot signal for synchronous detection is different.
[0055]
(Tenth embodiment)
FIG. 16 is a block diagram showing a configuration of a receiving apparatus for direct spread spectrum communication according to the tenth embodiment of the present invention.
In the receiving apparatus according to this embodiment, an averager 29 that time-averages the correlation power value from the power measuring device 28 is provided at the subsequent stage of the power measuring device 28 of each RAKE finger 20 ″ constituting the RAKE receiver 5 ″. It has been. Since the other configuration is the same as the configuration of FIG. 7, the description of the overlapping portion is omitted. The present embodiment corresponds to a system in which a channel for transmitting data and a channel for transmitting system timing and phase are spread by different spreading codes and transmitted in parallel.
[0056]
According to the present embodiment, the correlation power value from the power measuring device 28 is averaged a plurality of times in the averager 29, and the result is transmitted to the controller 6. There is no need to average on the controller 6 side. By such processing, it is possible to average the multipath intensity information actually received over a long period of time, reduce fluctuations due to fading, and improve the path search capability of the receiving apparatus. As a result, the reception performance of the reception device can be improved.
[0057]
(Eleventh embodiment)
FIG. 17 is a block diagram showing a configuration of a receiving apparatus for direct spread spectrum communication according to the eleventh embodiment of the present invention.
In addition to the configuration of the tenth embodiment shown in FIG. 16, the receiver according to this embodiment is provided with a timer 8 for controlling the operation timing of the power measuring device 28 and the averager 29 of each RAKE finger 20 ″. Note that this embodiment also corresponds to a system in which a channel for transmitting data and a channel for transmitting the timing and phase of the system are spread by different spreading codes and transmitted in parallel. It is.
[0058]
Also in the present embodiment, the correlation power value from the power measuring device 28 is averaged a plurality of times in the averager 29, and the result is transmitted to the controller 6. This averaging is performed by radio transmission. It is not necessary to always operate because it is only necessary to make an average that can suppress the fluctuation of the road intensity. According to the present embodiment, the timer 8 that controls the operation timing of the power measuring device 28 and the averager 29 is provided. Timing can be controlled. As a result, it is possible to reduce the processing amount while making it possible to average the intensity information of the multipath actually received over a long period of time. Therefore, the CDMA receiver of the present invention can suppress power consumption while improving reception performance.
In the above embodiments, each function has been described as having an independent configuration, but some of these components can be realized on one CPU.
[0059]
【The invention's effect】
As described above in detail, according to the present invention, in the direct spread spectrum communication system, it is possible to improve the detection accuracy of the path assigned to the RAKE finger, so that the reception characteristic can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a receiving apparatus for direct spread spectrum communication according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a configuration of a reception signal received by the reception device.
FIG. 3 is a block diagram of a power measuring device of a path search finger in the receiving apparatus.
FIG. 4 is a diagram showing a delay profile obtained by path search from the received signal.
FIG. 5 is a flowchart showing a path search procedure according to the first embodiment;
FIG. 6 is a timing chart of the same path search.
FIG. 7 is a block diagram showing a configuration of a receiving apparatus for direct spread spectrum communication according to a second embodiment of the present invention.
FIG. 8 is a block diagram of a transmission path response estimation unit and a power measuring device of a RAKE finger in the receiving apparatus.
FIG. 9 is a flowchart showing a path search procedure according to the second embodiment.
FIG. 10 is a timing chart of the same path search.
FIG. 11 is a flowchart showing a path search procedure according to the third embodiment;
FIG. 12 is a timing chart of the same path search.
FIG. 13 is a flowchart showing a path search procedure according to the fourth embodiment.
FIG. 14 is a timing chart of the same path search.
FIG. 15 is a block diagram showing a configuration of a receiving apparatus for direct spread spectrum communication according to a ninth embodiment of the present invention.
FIG. 16 is a block diagram showing a configuration of a receiving apparatus for direct spread spectrum communication according to a tenth embodiment of the present invention.
FIG. 17 is a block diagram showing a configuration of a receiving apparatus for direct spread spectrum communication according to an eleventh embodiment of the present invention.
[Explanation of symbols]
1 ... Antenna
2 ... R / F part
3 ... A / D converter
4, 4 '... Path search part
5,5 ', 5 "... RAKE receiver
6 ... Controller
7 ... Memory
8 ... Timer
10 ... Pass search finger
11, 21 ... Correlator for common pilot
12, 23 ... Scramble code generator
13, 28 ... Electric power measuring device
14 ... Correlator for pilot
20, 20 ', 20 "... RAKE finger
22 ... Data correlator
24 ... Channelizing code generator
25 ... Transmission path response estimator
26: Complex multiplier
27: Path delay compensator
30 ... Adder

Claims (12)

Obtaining a correlation power value for each delay time between the received direct spread spectrum signal and the spread code to generate a current (t _n ) instantaneous delay profile;
Each correlation power value of the current instantaneous delay profile is multiplied by a coefficient α (0 <α <1), and each correlation power value of the cumulative delay profile, which is the entire history of the past (t _{1 to} t _n-1 ), is obtained. Multiplying by a factor (1-α) and adding the multiplication results for each delay time to generate a first new cumulative delay profile;
Determining a current (t _m ) instantaneous correlation power value in each path with a plurality of RAKE fingers to which each of the plurality of paths is assigned;
The obtained instantaneous correlation power value of each path is multiplied by a coefficient β (0 <β ≦ 1), and a cumulative correlation power value that is the entire history of each path in the past (t _{1 to} t _m-1 ). Multiplying the coefficient by (1-β) and adding the multiplication results for each path to calculate a new cumulative correlation power value for each path;
Adding a new cumulative correlation power value for each path to the first new cumulative delay profile for each path to generate a second new cumulative delay profile;
Determining a plurality of paths to be RAKE-combined based on the second new cumulative delay profile; and a path search method for direct spread spectrum communication. Obtaining a correlation power value for each delay time between the received direct spread spectrum signal and the spread code to generate a current (t _n ) instantaneous delay profile;
Each correlation power value of the current instantaneous delay profile is multiplied by a coefficient α (0 <α <1), and each correlation power value of the cumulative delay profile, which is the entire history of the past (t _{1 to} t _n-1 ), is obtained. Multiplying by a factor (1-α) and adding the multiplication results for each delay time to generate a first new cumulative delay profile;
Determining a current (t _m ) instantaneous correlation power value in each path with a plurality of RAKE fingers to which each of the plurality of paths is assigned;
The obtained instantaneous correlation power value of each path is multiplied by a coefficient β (0 <β ≦ 1), and a cumulative correlation power value that is the entire history of each path in the past (t _{1 to} t _m-1 ). Multiplying the coefficient by (1-β) and adding the multiplication results for each path to calculate a new cumulative correlation power value for each path;
A result of multiplying the new cumulative correlation power value of each path by a coefficient γ (γ> 1) is added to the first new cumulative delay profile for each path to obtain a second new cumulative power. Generating a delay profile;
Determining a plurality of paths to be RAKE-combined based on the second new cumulative delay profile; and a path search method for direct spread spectrum communication. Monitoring whether the calculated cumulative correlation power value of each new path satisfies a predetermined threshold;
For paths that the cumulative correlation power value does not satisfy a predetermined threshold value in this step, direct sequence spread spectrum according to claim 1 or 2, further comprising the step of removing the assignment of the path from the RAKE fingers Communication path search method. Obtaining a correlation power value for each delay time between the received direct spread spectrum signal and the spread code to generate a current (t _n ) instantaneous delay profile;
Calculating a signal power to interference power ratio by dividing each correlation power value of the current instantaneous delay profile by the interference power value;
Each signal of the cumulative delay profile which is the entire history of the past (t _{1 to} t _n-1 ) is obtained by multiplying each signal power to interference power ratio of the current instantaneous delay profile by a coefficient α (0 <α <1). Multiplying the power-to-interference power ratio by a factor (1-α) and adding the multiplication results for each delay time to generate a first new cumulative delay profile;
Obtaining a current (t _m ) instantaneous correlation power value and instantaneous interference power value in each path with a plurality of RAKE fingers to which each of the plurality of paths is assigned;
Calculating an instantaneous signal power to interference power ratio of each path obtained by dividing the current instantaneous correlation power value of each path determined by the instantaneous interference power value;
The calculated current instantaneous signal power-to-interference power ratio of each path is multiplied by a coefficient β (0 <β ≦ 1), and a cumulative total of past history (t _{1 to} t _m-1 ) of each path. Multiplying the signal power to interference power ratio by a factor (1-β) and adding the multiplication results for each path to calculate a new cumulative signal power to interference power ratio for each path;
Adding a new cumulative signal power to interference power ratio for each path to the first cumulative delay profile for each path to generate a second new cumulative delay profile;
Determining a plurality of paths to be RAKE-combined based on the second new cumulative delay profile; and a path search method for direct spread spectrum communication. Obtaining a correlation power value for each delay time between the received direct spread spectrum signal and the spread code to generate a current (t _n ) instantaneous delay profile;
Calculating a signal power to interference power ratio by dividing each correlation power value of the current instantaneous delay profile by the interference power value;
Each signal of the cumulative delay profile which is the entire history of the past (t _{1 to} t _n-1 ) is obtained by multiplying each signal power to interference power ratio of the current instantaneous delay profile by a coefficient α (0 <α <1). Multiplying the power-to-interference power ratio by a factor (1-α) and adding the multiplication results for each delay time to generate a first new cumulative delay profile;
Obtaining a current (t _m ) instantaneous correlation power value and instantaneous interference power value in each path with a plurality of RAKE fingers to which each of the plurality of paths is assigned;
A step of calculating an instantaneous signal power-to-interference power ratio of each path obtained by dividing the obtained current instantaneous correlation power value of each path by an instantaneous interference power value; and The interference power ratio is multiplied by a coefficient β (0 <β ≦ 1), and the cumulative signal power-to-interference power ratio, which is the entire history of each path in the past (t _{1 to} t _m-1 ), is expressed by a coefficient (1-β). And adding the multiplication results for each path to calculate a new cumulative signal power to interference power ratio for each path;
The result of multiplying the new cumulative signal power to interference power ratio of each path by a coefficient γ (γ> 1) is added to the first cumulative delay profile for each path to obtain a second new cumulative Generating a dynamic delay profile;
Determining a plurality of paths to be RAKE-combined based on the second new cumulative delay profile; and a path search method for direct spread spectrum communication. Monitoring whether the calculated cumulative signal power to interference power ratio of each new path satisfies a predetermined threshold;
For paths that the cumulative signal power to interference power ratio does not satisfy the predetermined threshold value in this step, according to claim 4 or 5, wherein it contains further a step of removing the assignment of the path from the RAKE fingers Direct spread spectrum path search method. Path search means for determining a correlation power value for each delay time between the received direct spectrum spread signal and the spread code and generating a current (t _n ) instantaneous delay profile;
A memory having a first storage area for storing a cumulative delay profile that is the entire history of the past (t _{1 to} t _n-1 );
Each correlation power value of the current instantaneous delay profile generated by the path search means is multiplied by a coefficient α (0 <α <1), and the past all history stored in the first storage area of the memory A cumulative delay profile generating means for multiplying each correlation power value of a cumulative delay profile by a coefficient (1-α) and adding the multiplication results for each delay time to generate a new cumulative delay profile;
Cumulative delay profile update for updating the cumulative delay profile by storing the generated new cumulative delay profile in the first storage area of the memory in place of the cumulative delay profile which is the entire past history. Means,
Path determining means for determining a plurality of paths to be RAKE combined based on a new cumulative delay profile stored in the first storage area of the memory;
A plurality of RAKE fingers for calculating a correlation power value in each path of a direct spread spectrum signal and a spread code received by being assigned to each of the plurality of paths determined by the path determination means, and calculated by these RAKE fingers A receiver for direct spread spectrum communication, comprising: a RAKE receiver having a RAKE combining means for RAKE combining correlation power values ;
The memory includes a second storage area and a third storage area,
The RAKE receiver includes instantaneous correlation power calculation means for obtaining a current (t _m ) instantaneous correlation power value in each path with the plurality of RAKE fingers ,
Wherein the second storage area of the memory cumulative correlation power value is the total history of past (t ₁ ~t _m-1) of said each path is stored,
The cumulative delay profile generation means multiplies the instantaneous correlation power value of each path obtained by the instantaneous correlation power calculation means by a coefficient β (0 <β ≦ 1) and holds it in the second storage area of the memory. The cumulative correlation power value, which is the entire past history of each path, is multiplied by a coefficient (1-β), and these multiplication results are added for each path to obtain the cumulative correlation power value of each new path. The calculated new cumulative correlation power value is stored in the second storage area of the memory in place of the cumulative correlation power value which is the entire past history of each path, and the cumulative correlation power is calculated. Update the value, add the cumulative correlation power value stored in the second storage area of the memory to the cumulative delay profile stored in the first storage area of the memory for each path, and A third description of the memory as a new cumulative delay profile. Is intended to be stored in the region,
The path determination means determines a plurality of paths to be RAKE combined based on a new cumulative delay profile stored in the third storage area instead of the first storage area of the memory. A receiver for direct spread spectrum communication characterized by the above. Path search means for determining a correlation power value for each delay time between the received direct spectrum spread signal and the spread code and generating a current (t _n ) instantaneous delay profile;
A memory having a first memory area for storing cumulative delay profile is a full history of the past _{(t 1 ~t n-1)} ,
Each correlation power value of the current instantaneous delay profile generated by the path search means is multiplied by a coefficient α (0 <α <1), and the past all history stored in the first storage area of the memory A cumulative delay profile generating means for multiplying each correlation power value of a cumulative delay profile by a coefficient (1-α) and adding the multiplication results for each delay time to generate a new cumulative delay profile;
Cumulative delay profile update for updating the cumulative delay profile by storing the generated new cumulative delay profile in the first storage area of the memory in place of the cumulative delay profile which is the entire past history. Means,
Path determining means for determining a plurality of paths to be RAKE combined based on a new cumulative delay profile stored in the first storage area of the memory;
A plurality of RAKE fingers for calculating a correlation power value in each path of a direct spread spectrum signal and a spread code received by being assigned to each of the plurality of paths determined by the path determination means, and calculated by these RAKE fingers A RAKE receiver having RAKE combining means for RAKE combining correlated power values;
A direct spread spectrum communication receiver comprising:
The memory includes a second storage area and a third storage area,
The RAKE receiver includes instantaneous correlation power calculation means for obtaining a current (t _m ) instantaneous correlation power value in each path with the plurality of RAKE fingers,
The second storage area of the memory stores a cumulative correlation power value that is the entire history of each path in the past (t _{1 to} t _m-1 ),
The cumulative delay profile generation means multiplies the instantaneous correlation power value of each path obtained by the instantaneous correlation power calculation means by a coefficient β (0 <β ≦ 1) and holds it in the second storage area of the memory. The cumulative correlation power value, which is the entire past history of each path, is multiplied by a coefficient (1-β), and these multiplication results are added for each path to obtain the cumulative correlation power value of each new path. The calculated new cumulative correlation power value is stored in the second storage area of the memory in place of the cumulative correlation power value which is the entire past history of each path, and the cumulative correlation power is calculated. The result of updating the value and multiplying the cumulative correlation power value stored in the second storage area of the memory by the coefficient γ (γ> 1) is stored in the first storage area of the memory for each path. To the new cumulative delay profile. Stored in the third storage area of the memory as
The path determination means determines a plurality of paths to be RAKE combined based on a new cumulative delay profile stored in the third storage area instead of the first storage area of the memory. receiver of direct spread spectrum communication you characterized. The path determination means monitors whether or not the calculated cumulative correlation power value of each new path satisfies a predetermined threshold, and for the path where the cumulative correlation power value does not satisfy the predetermined threshold, receiver of direct sequence spread spectrum communication according to claim 7 or 8, wherein the is intended to remove the assignment of the path from the RAKE fingers. Path search means for determining a correlation power value for each delay time between the received direct spectrum spread signal and the spread code and generating a current (t _n ) instantaneous delay profile;
A memory having a first storage area for storing a cumulative delay profile that is the entire history of the past (t _{1 to} t _n-1 );
A signal power to interference power ratio obtained by dividing each correlation power value of the current instantaneous delay profile generated by the path search means by an interference power value is multiplied by a coefficient α (0 <α <1), and the first of the memory Multiply each signal power-to-interference power ratio of the cumulative delay profile, which is all past history stored in the storage area, by a coefficient (1-α), and add these multiplication results for each delay time to newly A cumulative delay profile generating means for generating a cumulative delay profile,
Cumulative delay profile update for updating the cumulative delay profile by storing the generated new cumulative delay profile in the first storage area of the memory in place of the cumulative delay profile which is the entire past history. Means,
Path determining means for determining a plurality of paths to be RAKE combined based on a new cumulative delay profile stored in the first storage area of the memory;
A plurality of RAKE fingers for calculating a correlation power value in each path of a direct spread spectrum signal and a spread code received by being assigned to each of the plurality of paths determined by the path determination means, and calculated by these RAKE fingers A receiver for direct spread spectrum communication, comprising: a RAKE receiver having a RAKE combining means for RAKE combining correlation power values ;
The memory includes a second storage area and a third storage area,
The RAKE receiver includes instantaneous correlation power calculation means for obtaining a current (t _m ) instantaneous correlation power value in each path with the plurality of RAKE fingers ,
Wherein the second storage area of the memory cumulative signal-to-interference power ratio is the total history of past (t ₁ ~t _m-1) of said each path is stored,
The cumulative delay profile generation means has a coefficient β (0 <0) for the instantaneous signal power to interference power ratio of each path obtained by dividing the instantaneous correlation power value of each path obtained by the instantaneous correlation power calculation means by the instantaneous interference power value. β ≦ 1), the cumulative signal-to-interference power ratio, which is the entire past history of each path held in the second storage area of the memory, is multiplied by a coefficient (1-β), and these multiplications The result is added for each path to calculate the cumulative signal power-to-interference power ratio of each new path, and the calculated new cumulative signal power-to-interference power ratio is calculated for all the past history of each path. and stored in place of certain cumulative signal power to interference power ratio in the second storage area of said memory to update said cumulative signal power to interference power ratio, stored in the second storage area of said memory The cumulative signal power to interference power ratio is calculated for each path in the first description of the memory. Is added to the cumulative delay profile stored in the area, which is stored in the third memory area of said memory so as the new cumulative delay profile,
The path determination means determines a plurality of paths to be RAKE combined based on a new cumulative delay profile stored in the third storage area instead of the first storage area of the memory. A receiver for direct spread spectrum communication characterized by the above. Path search means for determining a correlation power value for each delay time between the received direct spectrum spread signal and the spread code and generating a current (t _n ) instantaneous delay profile;
A memory having a first memory area for storing cumulative delay profile is a full history of the past _{(t 1 ~t n-1)} ,
A signal power to interference power ratio obtained by dividing each correlation power value of the current instantaneous delay profile generated by the path search means by an interference power value is multiplied by a coefficient α (0 <α <1), and the first of the memory Multiply each signal power-to-interference power ratio of the cumulative delay profile, which is all past history stored in the storage area, by a coefficient (1-α), and add these multiplication results for each delay time to newly A cumulative delay profile generating means for generating a cumulative delay profile,
Cumulative delay profile update for updating the cumulative delay profile by storing the generated new cumulative delay profile in the first storage area of the memory in place of the cumulative delay profile which is the entire past history. Means,
Path determining means for determining a plurality of paths to be RAKE combined based on a new cumulative delay profile stored in the first storage area of the memory;
A plurality of RAKE fingers for calculating a correlation power value in each path of a direct spread spectrum signal and a spread code received by being assigned to each of the plurality of paths determined by the path determination means, and calculated by these RAKE fingers A RAKE receiver having RAKE combining means for RAKE combining correlated power values;
A direct spread spectrum communication receiver comprising:
The memory includes a second storage area and a third storage area,
The RAKE receiver includes instantaneous correlation power calculation means for obtaining a current (t _m ) instantaneous correlation power value in each path with the plurality of RAKE fingers,
The second storage area of the memory stores a cumulative signal-to-interference power ratio that is the entire history of each path in the past (t _{1 to} t _m-1 ),
The cumulative delay profile generation means has a coefficient β (0 <0) for the instantaneous signal power to interference power ratio of each path obtained by dividing the instantaneous correlation power value of each path obtained by the instantaneous correlation power calculation means by the instantaneous interference power value. β ≦ 1), the cumulative signal-to-interference power ratio, which is the entire past history of each path held in the second storage area of the memory, is multiplied by a coefficient (1-β), and these multiplications The result is added for each path to calculate the cumulative signal power-to-interference power ratio of each new path, and the calculated new cumulative signal power-to-interference power ratio is calculated for all the past history of each path. Instead of a certain cumulative signal power to interference power ratio, storing in the second storage area of the memory to update the cumulative signal power to interference power ratio, and the accumulation stored in the second storage area of the memory The result of multiplying the signal power to interference power ratio by the coefficient γ (γ> 1) Adding to the cumulative delay profile stored in the first storage area of the memory for each pass, and storing this in the third storage area of the memory as a new cumulative delay profile;
The path determination means determines a plurality of paths to be RAKE combined based on a new cumulative delay profile stored in the third storage area instead of the first storage area of the memory. receiver of direct spread spectrum communication you characterized. The path determination unit monitors whether the calculated cumulative signal power to interference power ratio of each new path satisfies a predetermined threshold, and the cumulative signal power to interference power ratio satisfies a predetermined threshold. for not satisfied path, the receiving apparatus of the direct spread spectrum communication according to claim 1 0 or 1 1, wherein a is intended to remove the assignment of the path from the RAKE fingers.

Images