JP3080156B2 - Automatic Gain Control Method for Frequency Hopping Communication Receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a GSM (Global Sy
The present invention relates to a frequency hopping communication receiver such as a telephone.

[0002] The present invention also relates to an automatic gain control method for the frequency hopping communication receiver.

[0003]

2. Description of the Related Art In a GSM system, each base station is assigned a group of transmission frequencies for a communication channel. The base station can switch these transmission frequencies at regular intervals according to a predetermined order.
Each of the mobile telephones as mobile stations within the service zone of a base station receives data from the base station to enable setting of a frequency hopping pattern for receiving data transmitted on the communication channel. .

A mobile telephone receiver operates, for example, to follow burst timing, frequency, and signal strength, to ensure that the receiver maintains synchronization with the transmitter, and to provide usable signals to the next stage. Have several control loops.

[0005] In particular, in the case of automatic gain control loops, for example, changes in signal strength can include normal attenuation depending on the distance between the transmitter and the receiver, and a direct path (direct pat).
h) Shadow fading caused by physical objects blocking the ray and Rayleigh caused by the receiver moving through multiple reflected signals
Caused by fading. Shadow fading has a spatial correlation that is considered common for many wavelengths. However, in Rayleigh fading, there is no correlation between bursts.

It is common to eliminate the effects of Rayleigh fading by averaging over multiple bursts.

[0007]

However, a problem arises when co-channel interference is present at one of the hopping frequencies. Such interference actually increases the signal strength at that frequency, even though the signal being received is not what is desired. For this reason, the gain decreases for all frequencies.

Therefore, an object of the present invention is to provide an automatic gain control method and an automatic gain control device for a frequency hopping receiver, which can significantly reduce the influence of co-channel interference at one hopping frequency. It is in.

Another object of the present invention is to provide a frequency hopping receiver that can significantly reduce the influence of co-channel interference at one hopping frequency.

[0010]

According to a first aspect of the present invention, there is provided an automatic gain control method for use in a frequency hopping communication receiver, wherein an average reception signal of signal bursts received at each of a plurality of different frequencies is provided. A first step of detecting a strength, a second step of detecting the presence of co-channel interference on any of the received signal bursts, and the average received signal strength for the received signal burst detecting the co-channel interference Weighting the average received signal strength as a weight reduced with respect to the weight applied to the average received signal strength related to other received signal bursts, and weighting the average received signal strength. Third output average value of intensity
And a fourth step of using the average value of the weighted average received signal strengths as a gain control signal, thereby obtaining an automatic gain control method for a frequency hopping communication receiver. Can be

[0011] According to a second aspect of the present invention, in the automatic gain control method for a frequency hopping communication receiver according to the first aspect, the second step comprises: determining an average received signal strength for a candidate burst. Comparing the average received signal strength for the other burst with the average received signal strength for the other burst, and comparing the average received signal strength for the other burst with an average value of the average received signal strength for the other burst by more than a predetermined amount. Determining that there is co-channel interference in the candidate burst. A method for automatic gain control for a receiver for frequency hopping communication is provided.

According to a third aspect of the present invention, in an automatic gain control device used for a frequency hopping communication receiver, a first method for detecting an average received signal strength of a signal burst received at each of a plurality of different frequencies. Means,
Second means for detecting the presence of co-channel interference for any of the received signal bursts, and weighting the average received signal strength for the received signal burst for which the co-channel interference was detected for another reception Weighting the average received signal strength as a weight reduced with respect to the weight given to the average received signal strength for the signal burst, and outputting an average value of the weighted average received signal strengths; Means and a fourth means for using the average value of the weighted average received signal strength as a gain control signal, whereby an automatic gain control apparatus for a frequency hopping communication receiver is obtained. .

[0013] According to a fourth aspect of the present invention, in the automatic gain control apparatus for a frequency hopping communication receiver according to the third aspect, the second means determines an average received signal strength for a candidate burst. Means for comparing with the average value of the average received signal strength for other bursts, and when the average received signal strength for the candidate burst exceeds the average value of the average received signal strength for the other bursts by a predetermined amount. Means for determining that co-channel interference is present in the candidate burst. An automatic gain control device for a frequency hopping communication receiver is obtained.

According to a fifth aspect of the present invention, a radio frequency input unit capable of tuning to a plurality of different center frequencies f1,..., Fn (n is an integer of 2 or more); A frequency hopping control unit for controlling the tuning so as to be sequentially tuned to the center frequencies f1,..., Fn, and a plurality of average receptions representing the average reception signal strength of the reception signal bursts at the center frequencies f1,. Average received signal strength detecting means for generating the signal strength values M1,..., Mn;
, Mn are respectively weighted with weights w1,..., Wn, and the gain of the radio frequency input unit is calculated according to the average value (w1M1 +,..., + WnMn) / n of these weighted average received signal strength values. , And gain control means for controlling the average received signal strength values M1,.
Comparing means for comparing the maximum value of Mn with the average value of the remaining (n-1) average received signal strength values; and the average received signal strength value M controlled by the comparison means.
When the maximum value of 1,..., Mn exceeds the average value of the remaining (n-1) average received signal strength values by a predetermined amount, the gain control means outputs the average received signal value. A receiver for frequency hopping communication characterized by including a weight reducing means for reducing the weight of the maximum value of the intensity values M1,..., Mn.

According to a sixth aspect of the present invention, there is provided a mobile station comprising the frequency hopping communication receiver according to the fifth aspect as a receiving section.

According to the configuration of the receiver for frequency hopping communication described above, when co-channel interference that significantly increases the average received signal strength value exists for one frequency, the average received signal strength for that frequency is determined. Reduce the weight of the value to zero or a positive value close to it,
Ensure that co-channel interference does not unduly affect the gain control loop.

Preferably, the receiver for frequency hopping communication further includes another control loop, for example, a timing control loop, and changes a control value according to a parameter measurement value at each frequency to be used. The weights of the parameter measurements are weighted w1,..., W obtained in the gain control loop as described above.
n, which also reduces the effects of co-channel interference in such other loops.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, there is shown a receiver for frequency hopping communication according to one embodiment of the present invention. This receiver for frequency hopping communication is used as a receiving unit in a GSM telephone, for example. This receiver for frequency hopping communication has an RF (radio frequency) input unit 1
Has zero. The RF input unit 10 has an input terminal 10a to which an automatic gain control (AGC) signal for determining the gain of the RF input unit 10 is input. The RF input unit 10 further includes:
It has an input terminal 10b to which a tuning signal for determining to which of a plurality of different center frequencies the RF input unit 10 is tuned at any time is input. RF input unit 10
In the above, both the automatic gain control operation by the automatic gain control signal and the tuning operation by the tuning signal are controlled by the main CPU (Central Processing Unit) 11.

The demodulation circuit 12 demodulates the received signal received by the RF input section 10 and outputs the demodulated signal. The decoder unit 13 receives and decodes the demodulated signal,
Output the decrypted data. The decoded data is sent to a dedicated digital signal processor (DSP) 14.
Is processed by the main CPU 1
1 is input.

As described above, the main CPU 11 converts the received signal received by the RF input unit 10 into a nearby base station based on data obtained by passing the signal through the demodulation circuit 12, the decoder unit 13, and the digital signal processor 14. The station communicates with this mobile phone using the frequencies f1, f2, f3,
, And fn are determined in what sequence, and the above-mentioned tuning signal is generated and sent to the RF input unit 10 so that the tuning of the RF input unit 10 can be performed by a known method not related to the gist of the present invention. Control synchronously.

The coded voice data contained in the signal burst from the base station received by the RF input unit 10 is decoded by the above-described decoder unit 13 and output by the digital signal processor 14. It is sent to the unit 15.

The sampling circuit 12 a connected to the RF input unit 10 periodically samples the received signal strength of the received signal received at the RF input unit 10 and sends the sampled signal to the digital signal processor 14.

Digital signal processor 14 stores and demodulates these sampled signals. Typically,
160 samples are stored for each frequency burst, and the digital signal processor 14 determines the mean received signal strength (Mean Received Sing) for each successive burst.
al Strength: MRSS) values M1, M2, M3, ..., Mn
And sends them to the main CPU 11.

The main CPU 11 processes all the MRSS values received in the frequency hopping cycle to obtain a gain value, which is used as the automatic gain control signal via the digital interface through the RF input unit 10.
To the input terminal 10a.

FIG. 2 is a flowchart showing a method for obtaining a gain value in each frequency hopping cycle in the main CPU 11 in the embodiment of the present invention described with reference to FIG.

At the start of each cycle, the variables CUM and MAX are reset to zero in step S20.

In step S21, the latest average received signal strength (MRSS) value is input from the digital signal processor 14 (DSP) to the main CPU 11, and in step S22, the value of the variable CUM is increased by the MRSS value (CUM). = CUM + MRSS).

In step S23, the MRSS value is
Compare with the value of variable MAX currently held,
If the value is larger, the variable MA is set in step S24.
An MRSS value is set as X, and thereafter, step S2
The operation proceeds to step 5. In step S23, MRSS
If the value is not greater than the variable MAX, step S2
The operation proceeds to step 5.

In step S25, it is determined whether or not the cycle has ended.
Repeat 24. If it is determined in step S25 that the cycle has ended, in step S26, the variable M
The final value held in AX is (CUM-MAX) / (N
Compare with the value of -1). Here, N represents the number of loops in each cycle, that is, the number n of hopping frequencies used. That is, (CUM-MAX) / (N
The value of -1) represents the average value of the received MRSS values in all iterations of the loop except when the maximum value is received.

If the difference obtained by subtracting the average value from the MAX value exceeds a predetermined amount (for example, 20 or 24 dB) (step S27), the gain value output by the main CPU 11 is changed to (C) in step S28.
UM-αMAX) / N. Here, α is a positive number of 1 or less. In step S27, when the difference obtained by subtracting the average value from the MAX value is equal to or smaller than the predetermined amount (for example, 20 or 24 dB), in step S29, the gain is calculated as the average value of all the MRSS values, that is, CUM / Set to N.

Here, in step S28 or step S29, a gain value (w1M1 + w2M2 +,..., + WnMn) / N is obtained. As described above, since N = n, the gain value can also be expressed as (w1M1 + w2M2 +,..., + WnMn) / n. This value is obtained by setting the individual values of w1 to wn to 1 for a frequency burst having no co-channel interference and setting a lower value for a frequency burst having co-channel interference. Of the signal M1
It is a weighted average from to Mn. This low value may be zero (if α is 1) or a value between zero and 1 (w _N = 1−α).

In controlling the timing and / or frequency values, if there is another active control loop,
The weights determined in the AGC loop described above are used in other loops to control them according to the weighted values of the corresponding measurements formed during the individual frequency bursts, and to control the other control loops. The effect of co-channel interference on proper operation can be minimized. For example, the weight determined in the AGC loop for one cycle can be used in the next cycle for another control loop.

[0034]

As described above, according to the present invention, 1
An automatic gain control method and apparatus for a frequency hopping receiver that can significantly reduce the effects of co-channel interference at two hopping frequencies.

Further, according to the present invention, there is provided a frequency hopping receiver capable of significantly reducing the influence of co-channel interference at one hopping frequency.

[Brief description of the drawings]

FIG. 1 is a simplified block diagram of a frequency hopping communication receiver according to one embodiment of the present invention.

FIG. 2 is a flowchart illustrating an automatic gain control method used in the frequency hopping communication receiver of FIG. 1;

[Explanation of symbols]

 Reference Signs List 10 RF input unit 10a input terminal 10b input terminal 11 main CPU 12 demodulation circuit 13 decoder unit 14 digital signal processor (DSP) 15 audio output unit 12a sampling circuit

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Lionel Poisson, Bakeshear Rg. 20 T.D., Reading, Imperial Way, Imperium, Level 3 NEC Technology (UK) Limited (56) References JP-A-60-186145 (JP, A) JP-A-8-195699 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B ^7/ 24-7/26 102 H04Q 7/00-7/38

Claims (6)

(57) [Claims] 1. An automatic gain control method used in a frequency hopping communication receiver, comprising: a first step of detecting an average received signal strength of signal bursts received at each of a plurality of different frequencies; A second step of detecting the presence of co-channel interference for any of the following, and weighting the average received signal strength for the received signal bursts that have detected the co-channel interference,
The average received signal strength is weighted as a weight reduced from the weight given to the average received signal strength for other received signal bursts, and an average value of the weighted average received signal strengths is output. 3. An automatic gain control method for a frequency hopping communication receiver, comprising: a third step; and a fourth step of using an average value of the weighted average received signal strength as a gain control signal. . 2. The method of claim 2, wherein the second step comprises: comparing an average received signal strength for a candidate burst with an average value of an average received signal strength for other bursts; Determining the presence of co-channel interference in the candidate burst if the average value of the average received signal strength for the burst exceeds a predetermined amount.
2. The automatic gain control method for a frequency hopping communication receiver according to claim 1, comprising: 3. An automatic gain control device for use in a frequency hopping communication receiver, comprising: first means for detecting an average received signal strength of signal bursts received at each of a plurality of different frequencies; Second means for detecting the presence of co-channel interference with any of the following, and weighting the average received signal strength for the received signal burst for which the co-channel interference has been detected,
The average received signal strength is weighted as a weight reduced from the weight given to the average received signal strength for other received signal bursts, and an average value of the weighted average received signal strengths is output. An automatic gain control apparatus for a frequency hopping communication receiver, comprising: third means; and fourth means for using an average value of the weighted average received signal strength as a gain control signal. . 4. The second means comprises: means for comparing an average received signal strength for a candidate burst with an average value of an average received signal strength for other bursts; and Means for determining that co-channel interference is present in said candidate bursts when the average value of the average received signal strength for the burst exceeds a predetermined amount. Automatic gain control for frequency hopping communication receiver. 5. A plurality of different center frequencies f1,..., Fn.
(N is an integer of 2 or more) that can be tuned to the center frequency f1,
, Fn, and a plurality of average received signal strength values M1,..., Mn representing the average received signal strength of received signal bursts at the center frequencies f1,. , Mn, and weights w for the average received signal strength values M1,..., Mn.
, Wn, respectively, and gain control means for controlling the gain of the radio frequency input unit according to the average value (w1M1 +,..., + WnMn) / n of the weighted average received signal strength values. And a comparing means for comparing the maximum value among the average received signal strength values M1,..., Mn with the average value of the remaining (n-1) average received signal strength values; The maximum value of the average received signal strength values M1,..., Mn is controlled so that the remaining (n-1)
When the average value of the average received signal strength values exceeds a predetermined amount, the gain control means decreases the weight for the maximum value of the average received signal strength values M1,..., Mn. A receiver for frequency hopping communication comprising: a reducing means. 6. A mobile station comprising the receiver for frequency hopping communication according to claim 5 as a receiver.