JPH11186998A - Mobile radio receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend the synchronization tracking range of a mobile radio receiver. SOLUTION: A synchronization acquisition control section 14 measures the period of a spread code by the input of an initial acquisition start signal 132, outputs the each phase of a correlation phase difference signal and outputs a synchronization acquisition end signal 142 after the end. A phase generating section 15 sums a reference phase signal 131 and a correlation phase difference signal 141, and outputs a correlation phase signal 151 to a correlation power arithmetic section 160. The arithmetic section 16 generates a receiver side spread code 110 and applies correlation arithmetic operation to the received signal for each period of the correlation phase difference signal 141. A synchronization position discrimination section 17 stores the correlation phase difference signal 141 that it to be maximum in the correlation power signal 161 as an initial synchronization position. The synchronization position discrimination section 17 receives the synchronization on acquisition end signal 142 to output the correlation phase difference signal 141 as an initial synchronization phase difference signal 171, compares it with a tracking phase difference signal 261 and outputs the synchronization phase difference signal 171 to the synchronization tracking section 12, when they do not match with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile radio communication by spread spectrum communication, in which a transmitting side transmits a spread signal obtained by multiplying a primary modulation signal by a predetermined code of a PN sequence,
A mobile radio receiver that receives a signal by detecting a position of phase synchronization by a correlation operation in which a receiving side changes a phase of a predetermined spreading code and multiplies the received signal by a product, and continues to follow a change in the received signal. It is about.

[0002]

2. Description of the Related Art A spread spectrum communication system is described, for example, in Kazuo Terada, "Digital Mobile Communication Technology", Japan Industrial Technology Center, page 125. The transmitting side of the spread spectrum communication uses a PN code (pseudo-random code) to send 1
The bandwidth of the signal of the next modulation is spread and transmitted, and the receiving side performs demodulation by despreading with the same code. PN code is +1
Alternatively, it is a code sequence having a value of -1, and the time width of one code level is called a chip. The correlation value obtained by multiplying and adding two PN codes for each chip for transmission and reception becomes high when the phases of the two are synchronized, and becomes close to 0 when the phases are different. Demodulation. On the other hand, since a received signal passes through a plurality of paths (paths) during propagation, a plurality of delayed waves having different phases are superimposed, and a change in a path due to a movement of a mobile station causes a change in each delayed wave. Electric power also changes every moment. The receiving device of the mobile station
The synchronization acquisition section performs a correlation operation between the received signal and the PN code by changing the latter phase, and assigns the phase of the initial acquisition at which the power becomes maximum to the synchronization tracking section as a synchronization position (a range of one chip or less). The synchronization follow-up unit configured by a delay locked loop (DLL) or the like follows the synchronization deviation between the received signal and the PN code that fluctuates due to a change in the path to one chip or less and supplies a clock signal to the data demodulation unit. Is configured.

[0003]

The circuit of the conventional synchronous follow-up unit has a limited follow-up range, and the power of the currently followed path is reduced or the reception path disappears due to the effects of fading or the like. Cannot be followed, and demodulation cannot be performed. In addition, since the phase of the synchronization position changes every chip time, there is a disadvantage that the delay time must be sufficiently considered when notifying the synchronization phase from the synchronization acquisition to the synchronization tracking circuit.

[0004] It is an object of the present invention to solve the above-mentioned drawbacks of the prior art and to provide a mobile radio receiving apparatus having an extended synchronization tracking range.

[0005]

According to the present invention, on the receiving side of mobile radio communication by spread spectrum communication, the position of synchronization with the received signal is calculated by performing a correlation operation with the received signal while changing the phase of a predetermined spread code. The mobile radio receiving apparatus including a synchronization acquisition section that captures the signal includes a counter that counts up at the timing between each of the spreading codes and outputs the reference phase signal, and the synchronization acquisition section performs a period of the spread code from the start of synchronization acquisition. Synchronization acquisition control means for counting up and outputting a correlation phase difference signal; phase generation means for adding a reference phase signal and a correlation phase difference signal and outputting a correlation phase signal indicating the sum thereof; A synchronization position determination unit that captures a synchronization position from the signal and the correlation phase signal and outputs the correlation phase signal at that time as a synchronization phase difference signal.

[0006] Such a mobile radio receiver preferably includes a synchronization phase generating means for adding the synchronization phase difference signal from the synchronization acquisition unit and the reference phase signal and outputting a synchronization phase representing the added value; A tracking phase control unit that sets a phase as an initial synchronization phase of the synchronization tracking operation, and a tracking phase difference that generates a tracking phase difference obtained by subtracting a reference phase from the tracking phase obtained by the tracking operation, and outputs the tracking phase difference to the synchronization position determination unit. A synchronization follow-up unit including a generation unit.

According to the present invention, the synchronization acquisition section continues the resynchronization acquisition even after the initial acquisition, compares the synchronization phase difference and the following phase difference signal, and if the two are different, reassigns the synchronization position. Therefore, even when it is difficult for the synchronization tracking unit to follow up, the tracking and demodulation operations can be continued. Also,
If the two are the same, no synchronization position is assigned, so that temporary interruption of the demodulation operation due to reassignment of the same path is prevented.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a mobile radio receiver according to the present invention; FIG.
FIG. 2 shows a mobile radio receiving apparatus according to an embodiment, and FIG. 2 is a diagram showing a phase relationship between spread codes for both transmission and reception. In FIG.
The notation P (i) represents the code of phase i, and the phase difference between the two spreading codes shown is X.

Referring to FIG. 1, a mobile radio receiving apparatus according to an embodiment captures a synchronous position with a received signal by calculating a correlation with the received signal while changing the phase of a predetermined spreading code on the receiving side, and acquires the synchronous position. Is applied to a mobile radio communication system by spread spectrum communication that tracks within a predetermined phase range,
Basically, it includes two functional units, a synchronization acquisition unit 11 and a synchronization follow-up unit 12, and a reference counter circuit 13. The synchronization acquisition unit 11
The phase of N (natural number) receiving spreading codes 110 (FIG. 2)
This is an initial synchronization acquisition function unit that performs initial acquisition for synchronizing the reception-side spread code 110 with the reception signal 100 by correlation operation performed by shifting by −1. That is, the synchronization acquisition unit 11 includes the reception signal 100, the initial acquisition start signal 132, the reference counter circuit
Reference phase signal 131 from 13 and tracking phase difference signal described later
261 is input, the initial acquisition operation and the resynchronization acquisition operation are performed on the received signal 100,
Has a function of outputting a synchronous phase difference signal 171 to the input terminal.

The synchronization tracking section 12 follows the fluctuation of the received signal 100 after the initial acquisition, detects a phase difference between the initial acquisition and the tracking, and outputs the detected phase difference to the synchronization acquisition section 11 as a tracking phase difference signal 261. This is a tracking function unit. When the reception signal 100 changes and the tracking is lost, the synchronization acquisition unit 11 outputs the synchronization phase again, so that the synchronization is continued. That is, the synchronization follow-up unit 12
Received signal 100, reference phase signal from reference counter circuit 13
131 and the synchronization phase difference signal 171 from the synchronization acquisition unit 11 are input, and a function of outputting a tracking phase difference signal 261 to the synchronization acquisition unit 11 and a synchronization spread code 241 is provided.

The reference counter circuit 13 is a counting circuit that performs a count-up operation of a spreading code cycle by a chip clock and outputs a counter value based on the counting as a reference phase signal 131 indicating a reference phase of the receiving-side spreading code. This counter value indicates the phase 0 to N-1 of each code of the N (natural number) spreading codes. The reference phase signal 131 is supplied to the synchronization acquisition section 11 and the synchronization tracking section 12.

The synchronization acquisition section 11 basically includes a synchronization acquisition control section 14, a phase generation section 15, a correlation power calculation section 16 and a synchronization position determination section 17 as shown in the figure. The synchronization acquisition control unit 14 performs the acquisition operation by using the phase difference signal for correlation.
141 is sequentially output to the correlation power calculating section 16 and the synchronous position judging section 17, and outputs a synchronous acquisition end signal 142 to the synchronous position judging section 17 when the acquiring operation is completed. In the synchronous acquisition control unit 14, an initial acquisition operation is performed by an initial acquisition start signal 132.
, And is performed for the entire phase difference range of the receiving-side spread code. In the synchronization acquisition control unit 14, a phase difference range for performing resynchronization acquisition can be set in advance. In the resynchronization acquisition operation following the initial acquisition operation, the acquisition operation is performed for the set phase difference range.

The phase generation unit 15 receives the correlation phase difference signal 141 from the synchronization acquisition control unit 14 and
And outputs the result of the addition to the correlation power calculation unit 16 as a correlation phase signal 151. The correlation power calculator 16 receives the received signal 100 and the correlation phase signal 151, sequentially generates a reception-side spread code corresponding to the input correlation phase signal 151, and generates the reception signal 100 and the reception-side spread code. Is a correlation operation function unit that performs a correlation operation in a predetermined correlation section. This predetermined correlation section can be preferably set in the correlation power calculation unit 16 in advance. The resulting correlation power signal 161 is output to synchronous position determination section 17.

The synchronous position judging section 17 sets a predetermined threshold value for judging the synchronous position. Of the sequentially input correlation power signals 161, the one that is larger and larger than the predetermined threshold value is regarded as the synchronous position. This is a determination function unit for determining. For this purpose, the synchronization position determination unit 17 has a storage unit (not shown) for storing the correlation phase difference signal 141 corresponding to the correlation power signal 161 determined to be the synchronization position. The determination result is output to the synchronization tracking section 12 as a synchronization phase difference signal 171. More specifically, the synchronization position determination unit 17 outputs the initial capture start signal 132
Performs an initial capturing operation in response to the input. In the initial acquisition operation, the correlation phase difference signal 141 corresponding to the correlation power signal 161 determined to be the synchronous position is stored. When the synchronization acquisition end signal 142 is input from the synchronization acquisition control unit 14, the stored phase difference signal is output as a synchronization phase difference signal 171. Thereafter, a resynchronization acquisition operation is performed, a similar acquisition operation is performed, and the correlation phase difference signal 141 corresponding to the correlation power signal 161 determined as the synchronization position is stored. Then, in response to the synchronization acquisition end signal 142, the tracking phase difference signal 261 from the synchronization tracking unit 12 described later is compared with the stored phase difference signal. If the two are not the same, the stored phase difference signal is compared. Is output as a synchronous phase difference signal 171. After the initial acquisition operation, the resynchronization acquisition operation is repeated. A predetermined allowable width is set in the determination unit 17 in the range for determining whether or not they are the same.

The synchronization tracking section 12 basically includes a phase error detection section 21, a phase control amount calculation section 22, a tracking phase control section 23, a spread code generation section 24, a synchronization phase generation section 25, The tracking phase difference generator 26 is configured. The phase error detection unit 21 includes a reception signal 100 and a spread code generation unit 24 described later.
When the error detection diffusion code 242 is input from the controller, the phase error detector 211 compares the phases of the two and outputs the phase error to the phase control amount calculator 22 as the phase error signal 211.

The phase control amount calculator 22 includes a phase error detector 21
An arithmetic circuit that calculates an update amount of the tracking phase so as to reduce the phase error in accordance with the phase error signal 211 input from the controller, and outputs a phase control amount signal 224 indicating the update amount to the tracking phase control unit 23. is there. The tracking phase control unit 23 is a functional unit that updates the tracking phase according to the phase control amount signal 224 input from the phase control amount calculation unit 22 as needed. The initial value of the tracking phase is set in a synchronization phase signal 251 input from a synchronization phase generation unit 25 described later. The initial value is updated in accordance with the phase control amount signal 224 that is thereafter input as needed, and a tracking phase signal 231 representing the updated value as the tracking phase is updated from the tracking phase control unit 23 to the spreading code generation unit 24 and the tracking code It is output to the phase difference generator 26.

The spreading code generator 24 generates the following phase signal 23
1 to generate a spread code synchronized with
This is a function unit that outputs as 1 and also outputs a spreading code necessary for phase error detection to the phase error detecting unit 21 as an error detecting spreading code 242. In a preferred embodiment,
The phase error detection unit 21 uses the principle of a delay locked loop (DLL) to detect the phase error. In this case, the error detecting spreading code 242 is a signal representing two spreading codes whose phases are shifted back and forth with respect to the synchronous spreading code 241 by a predetermined value △ / 2.

The synchronous phase generator 25 includes a reference counter circuit 13
Reference phase signal 131 from the controller and the synchronization position determination unit of the synchronization acquisition unit
And a synchronous phase difference signal 171 representing the result of the addition.
It has an addition operation function to output to Further, the tracking phase difference generation unit 26 receives the reference phase signal 131 from the reference counter circuit 13.
And a tracking phase signal 231 from the tracking phase control unit 23 described above, and calculates a tracking phase difference signal 261 indicating the phase difference to the synchronization position determination unit 17 of the synchronization acquisition unit 11. This is a phase difference detection circuit for outputting.

FIG. 3 shows signals appearing in each section of the synchronization acquisition section 11. The reference counter circuit 13 counts the chip clock and outputs a counter value based on the count as a reference phase signal 131. As described above, this counter value indicates the phase 0 to N-1 of each code of the N spreading codes. In FIG. 2, the receiving spread code 110 and the receiving spread code 110, which have the initial phase X, are shifted by -1 for every phase (0 to N-1). After one cycle of 13, the phase difference becomes X + N-1.
Needs to be corrected. This correction is performed as follows.

Referring to FIG. 3, upon receiving the initial capture start signal 132, the synchronous capture control unit 14 of the synchronous capture unit 11 enters the initial capture operation mode. In the initial acquisition operation, the synchronization acquisition control unit 14 generates the correlation phase difference signal 141 for the phases 0 to N−1 in the code section corresponding to the count-up of the spread code cycle.
Is output. When this is completed for all phases, a synchronization acquisition end signal 142 is output to the synchronization position determination unit 17. The phase generation unit 15 receives the reference phase signal 131 from the reference counter circuit 13.
When the correlation phase difference signal 141 from the synchronization acquisition control unit 14 is input, the sum is obtained, and the correlation phase signal 151 representing the sum is output to the correlation power calculation unit 16. With this signal, the counter phase difference X + 1-N (FIG. 2) between the received signal 100 and the receiving-side spread code 110 is corrected to the phase difference X-1 (FIG. 3). The correlation power calculation unit 16 generates a reception-side spread code 110 corresponding to the correlation phase difference signal 141, and performs a correlation calculation with the input reception signal 100 for each section of the correlation phase difference signal 141. The resulting correlation power signal 161 is output to synchronous position determination section 17.

The synchronous position determination unit 17 includes a correlation power calculation unit 16
The correlation power signal 161 is sequentially input, and the correlation phase difference signal 141 is sequentially input from the synchronization acquisition control unit 14. When the initial acquisition start signal 132 is input, the synchronization position determination unit 17 identifies a signal that exceeds a predetermined threshold and is the largest among the correlation power signals 161 and identifies a correlation phase difference signal 141 corresponding thereto. It is stored as the initial synchronization position. And
When the synchronization end signal 142 indicating the end of all phases is input, the stored signal is converted to the initial synchronization phase difference signal 17.
It outputs to the synchronization follow-up unit 12 as 1.

After such an initial synchronization acquisition operation, the synchronization position determination unit 17 performs a resynchronization acquisition operation. The resynchronization acquisition operation is performed in the same manner as the initial synchronization acquisition operation. That is, the synchronous position determination unit 17 obtains and stores the correlation phase difference signal 141 corresponding to the correlation power signal 161 sequentially input from the correlation power calculation unit 16. Sync end signal 14
2 is input from the synchronization acquisition control unit 14, the synchronization position determination unit 17 transmits the stored correlation phase difference signal to the synchronization tracking unit.
Compare with the tracking phase difference signal 261 from 12. If the stored correlation phase difference signal is not the same as the tracking phase difference signal 261, the stored phase difference signal is used as the synchronization phase difference signal.
171 is output to the synchronization follow-up unit 12. Thereafter, the synchronization acquisition operation is similarly repeated.

In the synchronization follower 12, a phase error detector 21
Is the input reception signal 100 and the error detection spread code 242
And outputs the phase error between them as a phase error signal 211. The phase error signal 211 does not represent the numerical value of the phase error, but is a signal corresponding to the phase error. The phase control amount calculation unit 22 calculates a follow-up phase update amount such that the phase error is reduced according to the phase error signal 211, and outputs the update amount as a phase control amount signal 221 to the follow-up phase control unit 23. . When the synchronization phase signal 251 is input from the synchronization phase generation unit 25, the tracking phase control unit 23 sets the synchronization phase signal 251 as an initial value of the tracking phase, and then sets the tracking phase value according to the phase control amount signal 221 that is input as needed. Is updated, and a tracking phase signal 231 is generated.

When the tracking phase signal 231 is input as described above, the spreading code generator 24 generates a spreading code synchronized with the tracking phase signal 231 and outputs it as a synchronization spreading code 241. Along with this, a diffusion code for error detection necessary for phase error detection
242 to the phase error detection unit 21. As described above, when the DLL method is used for the phase error detection in the phase error detection unit 21, the error detection spread code 242 is
241 are two spreading codes whose phases are shifted back and forth by a predetermined value △ / 2. FIG. 4 shows an example.

Therefore, the tracking phase difference generator 26 receives the tracking phase signal 231 from the tracking phase controller 23 and the reference counter circuit 13
And outputs a tracking phase difference signal 261 indicating the difference to the synchronization position determination unit 17 of the synchronization acquisition unit 11. Synchronous position determination unit 17 receiving this
Determines that the difference between the following phase difference signal 261 and the synchronous phase difference signal 171 at that time is within a predetermined value, and does not update the synchronous phase difference signal 171. An example of information exchange between the synchronization acquisition unit 11 and the synchronization follow-up unit 12 using the synchronization phase difference signal 171 and the follow-up phase difference signal 261 will be described below.

Synchronous phase difference signal 171 = A ⇒ Tracking phase signal 231 = A Tracking phase difference signal 261 Phase control amount signal 221 = -1 ⇒ Tracking phase signal 231 = A-1 221 = -1 ⇒ Tracking phase signal 231 = A -2 221 = 0 ⇒ Tracking phase signal 231 = A-2 221 = 1 ⇒ Tracking phase signal 231 = A-1 Synchronous phase difference signal 171 = B ⇒ Tracking phase signal 231 = B In the case of DLL system, the PN code position When the phase difference becomes △ / 2 or more, tracking becomes impossible. At this time, the synchronization phase difference signal 171 is again output from the synchronization acquisition unit 11 to the synchronization tracking unit 12, and demodulation can be continued.

There is an application example in which the synchronization follower and the demodulator are configured to estimate a propagation path from a past phase change. In such an application example, when a new synchronization phase difference signal is output, the channel estimation is initialized. In order to prevent such an interruption of the demodulation operation, the synchronous phase difference signal 171 is not output when it is determined that the synchronous phase difference signal 171 and the following phase difference signal 261 are the same.

As described above, according to the present embodiment, in the synchronization acquisition operation, the synchronization acquisition control unit 14 continuously performs the resynchronization acquisition operation even after the end of the initial acquisition. Therefore, even when the synchronization tracking becomes difficult in the synchronization tracking unit 12, a new synchronization position is allocated from the synchronization acquisition unit 11 to the synchronization tracking unit 12. Further, by comparing the synchronization phase obtained during the resynchronization acquisition operation with the tracking phase difference signal, it is possible to prevent a temporary interruption of the demodulation operation due to reassignment of the same path.

Further, the output of the synchronization phase to the synchronization tracking section 12 and the output of the tracking phase to the synchronization acquisition section 11 are performed by using the synchronization phase difference signal 171 and the tracking phase difference signal 261 respectively. The notification can be made without having to consider the delay.

[0030]

As described above, according to the present invention, the synchronization acquisition section continues the resynchronization acquisition even after the initial acquisition, compares the synchronization phase difference and the following phase difference signal, and if both are different, re-synchronizes the synchronization position. Since the allocation is performed, the tracking and the demodulation operation are continued even when the tracking of the synchronous tracking unit is difficult. If the two are the same, no synchronization position is assigned, so that temporary interruption of the demodulation operation due to reassignment of the same path is prevented.

By using the synchronization phase difference signal and the tracking phase difference signal, the synchronization phase and the tracking phase can be notified between the synchronization acquisition section and the synchronization tracking section without considering the delay.

[Brief description of the drawings]

FIG. 1 is a functional configuration diagram of a mobile radio receiving apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a phase relationship between spread codes for both transmission and reception in the embodiment shown in FIG. 1;

FIG. 3 is a diagram illustrating an example of a signal appearing in each unit of a synchronization acquisition unit according to the embodiment illustrated in FIG. 1;

FIG. 4 is a diagram illustrating an example of phase error detection in the case of a DLL method.

[Explanation of symbols]

 10 Mobile radio receiver 11 Synchronization acquisition unit 12 Synchronization tracking unit 15 Phase generation unit 25 Synchronization phase generation unit 26 Tracking phase difference generation unit

Claims (4)

[Claims] 1. A mobile station including a synchronization acquisition unit for acquiring a synchronization position with a received signal by performing a correlation operation with the received signal while changing a phase of a predetermined spread code on a receiving side of mobile radio communication based on spread spectrum communication. In the wireless receiving device,
The device includes a counter that counts up at a timing between each of the spread codes and outputs the reference phase signal, and the synchronization acquisition unit counts up a period of the spread code from the start of synchronization acquisition to perform correlation. Synchronization acquisition control means for outputting a phase difference signal, phase generation means for adding the reference phase signal and the correlation phase difference signal and outputting a correlation phase signal indicating the sum thereof, the reception signal and the correlation A mobile radio receiving apparatus comprising: a synchronous position determining unit that captures the synchronous position from the use phase signal and outputs the correlation phase signal at that time as a synchronous phase difference signal. 2. The apparatus according to claim 1, further comprising a synchronization tracking section, wherein the synchronization tracking section adds the synchronization phase difference signal and the reference phase signal, and calculates an added value. Synchronous phase generating means for outputting a synchronous phase to be represented; tracking phase control means for setting the synchronous phase as an initial synchronous phase of the synchronous tracking operation; and generating a tracking phase difference by subtracting the reference phase from the tracking phase by the synchronous tracking operation. And a tracking phase difference generating means for outputting the tracking phase difference to the synchronous position determining means. 3. The apparatus according to claim 2, wherein the synchronization position determination means compares the tracking phase difference from the tracking phase difference generation means with the synchronization phase difference signal. A mobile radio receiving apparatus for outputting the correlation phase signal to a synchronous phase generating means. 4. The mobile radio receiving apparatus according to claim 2, wherein said synchronization follow-up unit uses a delay locked loop system.