JP3163528B2 - Wireless communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication, and more particularly to a technique for automatically adjusting transmission power in mobile communication.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIGS. 8, 9 and 10. FIG. FIG. 8 is a diagram showing the overall configuration when the conventional example is implemented, FIG. 9 is a diagram showing a target value of the received signal power in the radio station A2-1, that is, a required received signal power, and FIG. FIG. In FIG. 9, the horizontal axis indicates time, and the vertical axis indicates required received signal power in the wireless station A2-1.

The power control of the radio station B2-2 is performed as follows. As shown in FIG. 8, based on the signal power of 2-3 received by the wireless station A2-1, the wireless station A2-1 sends the received signal of the wireless station A2-1 to the wireless station B2-2. The power control signal is set to 2- so that the power becomes constant as shown in FIG.
4 and the wireless station B2-2 controls 2-3 transmission power according to the power control signal. The power control signal is stored together with the transmission data in a frame configuration as shown in FIG. 10, and is transmitted one bit per frame (whether the transmission signal power is increased or decreased by a certain value α). Here, the reception power refers to the reception power including all the noise components and the radio signal components that the radio station is receiving at that time, and the reception signal power is the desired reception power that the radio station is receiving at that time. , The received signal power of only the wireless signal component from the wireless station, that is, the received signal power of the desired signal.

Next, the operation of the conventional example will be described with reference to FIG. FIG. 11 is a flowchart showing the operation of the conventional example when power control is performed in the wireless station B2-2. In the conventional example, the wireless station A2-1 detects the received signal power from the wireless station B2-2 (S3-1). If the received signal power is larger than the required received signal power (S3-2), the wireless station A2-1 receives the wireless signal. The station A2-1 transmits a 1-bit control signal requesting a reduction in the transmission power of the wireless station B2-2 to the wireless station B2-2 (S3-5), and the wireless station B receiving the control signal
Step 2-2 lowers the transmission power by a certain value α (S3-6), and returns to the original state. On the other hand, if the received signal power is equal to or less than the required received signal power (S3-2), the wireless stations A2-1 to B2-2
Transmits a 1-bit control signal requesting that the transmission power be increased (S3-3), and upon receiving the control signal, the wireless station B2-2 increases the transmission power by a constant value α (S3-4);
Return to the original.

Further, an error in power control in the conventional example will be described with reference to FIG. 12A, 12B, and 12C, the horizontal axis represents time, and the vertical axis represents signal power. FIG. 12A is a diagram illustrating a relationship between the received signal power, the quantized received signal power, and the required received signal power, and FIG. 12B illustrates [(received signal power) − (quantized received signal power). FIG. 12C is a diagram illustrating a quantization error defined by [power]] [dB], and FIG. 12C is defined by [(quantized received signal power) − (required received signal power)] [dB]. FIG. 4 is a diagram illustrating a power control amount based on a power control signal. As shown in FIG. 12A, the received signal power fluctuates at high speed due to fading received on the propagation path. On the other hand, in the conventional example, the power control signal length in the frame is 1 bit.
Power control is performed by the received signal power quantized with the step size α as shown in FIG. 12A, and as shown in FIG. 12B, [(received signal power) − (quantized received signal Power)] [dB]. Therefore, the actual power control amount is as shown in FIG. 12C, and the conventional example has a disadvantage that the power control error increases.

[0006]

In such a conventional technique, since the bit length of the power control signal for changing the transmission power added in the radio station is 1, the power control error increases. . Further, if the bit length of the power control signal is increased, the power control error can be reduced, but the ratio of the power control signal in the data frame increases. These are not preferable from the viewpoint of effective use of radio waves.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and has a required reference value of the received signal power and a required reference signal power while reducing the power control error by making the bit length of the power control signal at least one. It is an object of the present invention to provide a wireless communication system capable of suppressing an increase in the ratio of the power control signal in the data frame by appropriately switching the bit length or the step size of the power control signal according to the relationship.

Another object of the present invention is to provide a radio communication system and a radio station device that can effectively use radio waves.

[0009]

A first aspect of the present invention is a radio communication method in which a plurality of radio stations are connected by radio signals, and the radio stations include a transmitter capable of changing the transmission signal power.

Here, the feature of the present invention is that the radio station A measures the received signal power of the radio signal coming from the radio station B at the radio station A and a required reference value of the received signal power. If [(received signal power at wireless station A) <(a reference value of received signal power at wireless station A)], then [((received signal power at wireless station A)-(wireless station A) The required signal power at A)] [dB] is represented by [−P · 2 ^(K−1) ≦ Y ₁ ≦ P · 2 ^(K−1) ] (K is an integer of 1 or more, P Is a positive real number), the value of the power control signal Y ₁ is determined by performing K-bit quantization with the step size P, and the power control signal Y ₁ and information indicating that the bit length of the power control signal is K Is added to the transmission signal from the wireless station A to the wireless station B, and [(received signal power at the wireless station A) ≧ (received signal power at the wireless station A) , The signal power corresponding to [((received signal power at wireless station A) − (required received signal power at wireless station A)] [dB] is [−P · 2 ^{(L -1)} ≦ Y ₂ ≦ P · 2 ^(L-1) ], and L-bit quantization (L is K
≧ L an integer of 1 or more) to satisfying determines the value of the power control signal Y _2, wireless and information indicating that the bit length of the power control signal Y ₂ and said power control signal is at the L from the radio station A Means for adding to a transmission signal to station B,
Is the transmission signal power of the wireless station B based on these signals, and if the bit length of the power control signal is K, [((the transmission signal power of the wireless station B immediately before adjustment) −Y ₁ ] [dB] , And when the bit length of the power control signal is L, it is adjusted to [(transmission signal power of wireless station B immediately before adjustment) −Y ₂ ] [dB].

A second aspect of the present invention is a wireless communication method in which a plurality of wireless stations are connected by wireless signals, and the wireless stations include a transmitter capable of changing the transmission signal power.

Here, the feature of the present invention is that the radio station D is provided with a transmitter capable of changing the transmission signal power, and the radio station C is provided with a radio station C for radio signals coming from the radio station D. Means for measuring the received signal power and the required reference value of the received signal power in the following manner: [(received signal power at wireless station C) <(a reference value of received signal power at wireless station C)] If so, the signal power corresponding to [(received signal power at wireless station C) − (required received signal power at wireless station C)] [dB] is set to [−Q · 2 ^(M−1) ≦ Y ₃ ≦ Q · 2 ^(M−1) ] (where M is an integer equal to or greater than 1 and Q is a positive real number), M bits are quantized with a step size Q to determine the value of the power control signal Y ₃ , Y ₃ and step size are Q
Is added to the transmission signal from the wireless station C to the wireless station D, and [(received signal power at the wireless station C) ≧ (a reference value of the received signal power at the wireless station C)] ], The signal power corresponding to [(received signal power at wireless station C) − (required received signal power at wireless station C)] [dB] is represented by [−R · 2 ^(M−1) ≦ Y ₄ ≦ R · 2 ^(M−1) ], and M-bit quantization (R is Q
≧ satisfy R positive real number) to determine the value of the power control signal Y _4, transmitted signal and information indicating that the power control signal Y ₄ and step size is R from the wireless station C to the radio station D Means for adding the transmission signal power of the radio station D based on these signals. If the step size is Q, the radio station D transmits ) −Y ₃ ] [dB], and when the step size is R, it is adjusted to [(transmission signal power of radio station D immediately before adjustment) −Y ₄ ] [dB].

[0013]

According to the present invention, transmission power control of a radio station can be performed using a power control signal of 1 bit or more, so that it is possible to more accurately follow high-speed fluctuations in the received signal power. In comparison, the power control error can be reduced. Also, as a required reference value of the received signal power,
If the median value of the received signal power is adopted, refer to the reference (William C. Jakes, “Microwa
ve MobileCommunications ",
John Wiley & Sons Inc. , P
p. 339 (1974)), when the received signal power fluctuates due to the Rayleigh distribution, the probability that the received signal power falls within the upper 5 dB with respect to the median value of the received signal power is 40.
%, And the probability of falling within the lower 5 dB is 26%.
This indicates that when the received signal power is larger than the median value of the received signal power, the level fluctuation amount is gradual, and the power control amount per time in the power control can be small. Therefore, when the received signal power is larger than the median of the received signal power, the number of quantization bits and the step size can be smaller than when the received signal power is smaller than the median of the received signal power, The ratio of the power control signal in the data frame can be reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the median value of received signal power is adopted as a required reference value of received signal power will be described below.

An embodiment of the present invention will be described with reference to FIGS. 1, 2, 3 and 4. FIG. 1 is a diagram showing the overall configuration when implementing an embodiment of the present invention. FIG. 2 is a diagram showing a target value of the received signal power in the wireless station A1-1, that is, a required received signal power. In FIG. 2, the horizontal axis represents time, and the vertical axis represents a target value of the received signal power at the wireless station A1-1, that is, the required received signal power. Radio station A
Signals transmitted from 1-1 constitute a frame. FIG.
FIG. 4 is a diagram showing an example of the configuration of a frame according to claim 1 of the present invention, and FIG. 4 is a diagram showing an example of the configuration of a frame according to claim 2 of the present invention. FIGS. 3A and 3B show that when the received signal power is smaller than the median value of the received signal power,
FIGS. 4A and 4B show the case where the received signal power is larger than the median value of the received signal power, respectively.
The case where the received signal power is smaller than the median value of the received signal power and the case where the received signal power is larger than the median value of the received signal power are shown.

First, the power control of the present invention will be described with reference to FIG. As shown in FIG. 1, based on the power received by the wireless station A1-1, the wireless station A1-1
2, a power control signal of 1 bit or more is transmitted so that the received signal power at the wireless station A1-1 is constant as shown in FIG. 2, and the wireless station B1-2 according to the power control signal Control transmission power.

Next, the structure of the frame will be described with reference to FIGS. A plurality of bits of a power control signal are assigned to the frame together with the transmission data. There are two types of frame configurations, which are switched and used as follows.

FIG. 3 shows an example of a frame configuration according to claim 1 of the present invention. In the radio station A1-1, if [(received signal power) <(median of the received signal power), the power control bits switching bit B ₁ and 0, [(received signal power) - (required received signal Power)] [dB], the signal power corresponding to [−P · 2 ^(K−1) ≦ Y ₁ ≦ P · 2 ^(K−1) ] is quantized to Y ₁ by K bits with a step size P,
Storing power control signal Y ₁ to K ₁ in the frame. If [(received signal power) ≧ (median of received signal power)], the signal power corresponding to [(received signal power) − (required received signal power)] [dB] is calculated as [−P · 2 ^(L−1) ≦ Y ₂ ≦ P · 2 ^(L−1) ], L bits are quantized (K ≧ L) to Y ₂ with a step size P, and the power control signal Y ₂ is L in the frame. Store in ₁ .

Next, FIG. 4 shows an example of a frame configuration according to claim 2 of the present invention. Similar to FIG. 3, the radio station A1-1, if [(received signal power) <(median of the received signal power), the step size switching bit B ₂ and 0, [(received signal power) - (required received signal power)] [dB] corresponding signal power to at ^{[-Q · 2 (M-1} ) ≦ Y 3 ≦ Q · 2 (M-1)] range Y ₃ step size Q of the M Bit quantization,
Storing power control signal Y ₃ to M ₁ in the frame. If [(received signal power) ≧ (median of received signal power)], the signal power corresponding to [(received signal power) − (required received signal power)] [dB] is calculated as [−R · 2 in the range of _{^{(M-1) ≦ Y 4}} ≦ R · 2 (M-1)], Y 4 to M-bit quantizer with a step size R was (Q ≧ R), M in the frame of the power control signal Y ₂ Store in ₁ .

Next, the operation of the present invention will be described with reference to FIGS.

FIG. 5 is a diagram showing an example of a flowchart according to claim 1 of the present invention. In the present invention, the wireless station A1-1 detects the received signal power from the wireless station B1-2 and the median of the received signal power (S1-1), and (received signal power)
<(Median of the received signal power) if (S1-2), sets the power control bits switching bit B ₁ to 0 (S1-3)
And the signal power corresponding to [received signal power−required received signal power] [dB] is [−P · 2 ^(K−1) ≦ Y ₁ ≦ P · 2
^{(K-1)] K-bit} quantization to Y ₁ in step size P in the range of (S1-4), and after storing the power control signals Y ₁ to K ₁ in the frame, the radio station frame B1-2 the transmission (S1-5), and the transmission signal power of the radio station B1-2 adjusted (S1-6) in the transmit signal power -Y ₁ regulation immediately before the radio station B] [dB], return to the beginning.

On the other hand, set if (received signal power) ≧ (the center value of the received signal power) (S1-2), the power control bits switching bit B ₁ to 1 (S1-7), [received signal power [Required received signal power] [dB] is a signal power corresponding to Y within a range of [−P · 2 ^(L−1) ≦ Y ₂ ≦ P · 2 ^(L−1) ].
₂ L-bit quantization with step size P (S1-8)
And, after storing the power control signal Y ₂ to L ₁ in the frame, and transmits (S1-9) the frame to the radio station B1-2,
The transmission signal power of the wireless station B1-2 is changed to [the wireless station B just before the adjustment.
To the transmission signal power of −Y ₂ ] [dB] (S1-10).
And then go back.

FIG. 6 is a diagram showing an example of a flowchart according to claim 2 of the present invention. In the present invention, the wireless station A1-1 detects the received signal power from the wireless station B1-2 and the median of the received signal power (S2-1), and (received signal power)
<Set (median of the received signal power) if (S2-2), the step size switching bit B ₂ to 0 (S2-3),
The signal power corresponding to [received signal power−required received signal power] [dB] is [−Q · 2 ^(M−1) ≦ Y ₃ ≦ Q · 2 ^(M−1) ]
In the range, M-bit quantization with a step size Q to Y ₃ (S2-4) and, M ₁ in the frame power control signal Y ₃
After that, the frame is transmitted to the wireless station B1-2 (S2
-5), and adjust the transmit signal power of the radio station B1-2 in the transmission signal power -Y ₃ adjustment immediately before the radio station B] [dB] (S
2-6) Then, return to the original. On the other hand, if (received signal power) ≧ (the center value of the received signal power), (S2-2), the step size switching bit B ₂ is set to 1 (S2-7), [received signal power - required received signal power] [dB] corresponding to the signal power in ^{[-R · 2 (M-1} ) ≦ Y 4 in the range of ^{≦ R · 2 (M-1} )], M -bit quantization with a step size R to Y ₄ ( S2
-8) and, after storing the power control signal Y ₄ to M ₁ in a frame, transmits frames to the radio station B1-2 (S2-9)
And, adjusting the transmission signal power of the radio station B1-2 in the transmission signal power -Y ₄ adjustment immediately before the radio station B] [dB] (S2-1
0) and return to the original.

Further, the power control error in the present invention will be described with reference to FIG. 7A, 7B, and 7C, the horizontal axis represents time, and the vertical axis represents signal power. FIG. 7A is a diagram illustrating the relationship between the received signal power, the quantized received signal power, and the required received signal power, and FIG. 7B illustrates [(received signal power) −
FIG. 7C is a diagram illustrating a quantization error defined by ((quantized received signal power)] [dB], and FIG. 7C illustrates [(quantized received signal power) − (required received signal power)]. [DB]
FIG. 6 is a diagram showing a power control amount based on a power control signal defined by the following equation. As shown in FIG. 7A, the received signal power fluctuates at high speed due to fading received on the propagation path. On the other hand, in the present invention, since the power control signal length in the data frame is 1 bit or more, the actual power control is performed on the received signal power at a multi-level level as shown in FIG. Be transformed into Therefore, in the present invention, as shown in FIG. 7B, a quantization error corresponding to (received signal power)-(quantized received signal power) occurs, but can be made smaller than in the conventional example. Therefore, the amount of power control by the power control signal is as shown in FIG. 7C, which has the advantage that the power control error is smaller than in the conventional example. Further, when the received signal power is larger than the median of the received signal power, the number of quantization bits and the step size can be made smaller than when the received signal power is smaller than the median of the received signal power, The ratio of the power control signal in the data frame can be reduced.

The median of the received signal power is the value of the radio station A
Can be calculated from the received signal power up to N frames before (N is an integer of 2 or more). Also, from the wireless station A to the wireless station B
Since the median value of the line to the wireless station B and that of the line from the wireless station B to the wireless station A are equal, there is a method of detecting the median value at the wireless station B and transmitting the information to the wireless station A. Information indicating the power control bit length and the step size may be transmitted from the wireless station A to the wireless station B.

In the embodiment of the present invention, an example is shown in which the median value of the received signal power is used as the required reference value of the received signal power. It can be performed.

In the embodiment of the present invention, an example of one-way power control has been described. However, the same control can be performed when power control is performed in two directions.

[0028]

As described above, according to the present invention,
It is possible to reduce the control error of the transmission power in the wireless station. Further, it is possible to reduce an increase in the ratio of the power control signal in the data frame. Therefore,
We can use radio waves effectively.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating a target value of a received signal power in a wireless station A1-1 according to the embodiment of the present invention.

FIG. 3 is a diagram showing an example of the configuration of a frame according to claim 1 of the present invention.

FIG. 4 is a diagram showing an example of the configuration of a frame according to claim 2 of the present invention.

FIG. 5 is a diagram showing a flowchart of claim 1 of the present invention.

FIG. 6 is a diagram showing a flowchart of claim 2 of the present invention.

FIG. 7 is a diagram illustrating a relationship among a received signal power, a quantized received signal power, and a required received signal power in the wireless station A1-1 according to the embodiment of the present invention.

FIG. 8 is a diagram showing an entire configuration of a conventional example.

FIG. 9 is a diagram showing a target value of a received signal power in a wireless station B2-1 in a conventional example.

FIG. 10 is a diagram showing a configuration of a data frame in a conventional example.

FIG. 11 is a flowchart showing the operation of the conventional example.

FIG. 12 is a diagram illustrating a relationship among a received signal power, a quantized received signal power, and a required received signal power in a wireless station A2-1 in a conventional example.

[Explanation of symbols]

 1-1 Radio station A 1-2 Radio station B 1-3 Line from radio station B to radio station A 1-4 Line from radio station A to radio station B 2-1 Radio station A 2-2 Radio station B 2-3 Line from radio station B to radio station A 2-4 Line from radio station A to radio station B

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-58690 (JP, A) JP-A 8-223113 (JP, A) JP-A 8-70274 (JP, A) JP-A 5- 227079 (JP, A) JP-A-4-233334 (JP, A) JP-A-61-203729 (JP, A) JP-A-5-268141 (JP, A) JP-A-5-129981 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 1/02-1/04 H04B 1/38-1/58 H04B ^7/ 24-7/26 H04Q ⁷ /00-7/38

Claims (2)

(57) [Claims] 1. In a wireless communication method in which a plurality of wireless stations are connected by wireless signals, a wireless station B includes a transmitter capable of changing its transmission signal power, and a wireless station A comes from the wireless station B. Radio signal A station
Means for measuring the received signal power at S and a required reference value of the received signal power, and [(the received signal power at the wireless station A) <(the reference value of the received signal power at the wireless station A)]. If so, the signal power corresponding to [(received signal power at wireless station A)-(required received signal power at wireless station A)] [dB] is calculated as [-P · 2 ^(K−1) ≦ Y ₁ ≦ P · 2 ^(K-1) ] (where K is an integer equal to or greater than 1 and P is a positive real number) and the value Y _{1 of} the power control signal quantized by K bits with the step size P
Is determined, and the power control signal Y ₁ and information indicating that the bit length of the power control signal is K are added to the transmission signal from the wireless station A to the wireless station B, and [(( If (received signal power) ≧ (the reference value of received signal power at wireless station A)], then [(received signal power at wireless station A) − (required received signal power at wireless station A)] [dB] ] In the range of [−P · 2 ^(L−1) ≦ Y ₂ ≦ P · 2 ^(L−1) ] and L-bit quantization (L is K
The value Y _{2 of} the power control signal obtained by ≧ L (an integer of 1 or more)
Means for determining the power control signal Y ₂ and information indicating that the bit length of the power control signal is L in a transmission signal from the wireless station A to the wireless station B. When the bit length of the power control signal is K based on these signals, if the bit length of the power control signal is K, [(transmission signal power of radio station B immediately before adjustment) −Y ₁ ] [dB] A wireless communication method comprising: adjusting the bit length of the power control signal to L (the transmission signal power of the wireless station B immediately before adjustment) −Y ₂ ] [dB] when the bit length is L. 2. In a wireless communication method in which a plurality of wireless stations are connected by wireless signals, the wireless station D includes a transmitter capable of changing the transmission signal power, and the wireless station C comes from the wireless station D. Radio signal radio station C
Means for measuring the received signal power and a required reference value of the received signal power in the following manner: [(received signal power at wireless station C) <(the reference value of received signal power at wireless station C)] If so, the signal power corresponding to [(received signal power at wireless station C) − (required received signal power at wireless station C)] [dB] is set to [−Q · 2 ^(M−1) ≦ Y ₃ ≦ Q · 2 ^(M−1) ] (where M is an integer equal to or greater than 1 and Q is a positive real number) and the value Y _{3 of} the power control signal quantized by M bits with the step size Q
And the power control signal Y ₃ and the step size are Q
Is added to the transmission signal from the wireless station C to the wireless station D, and [(the received signal power at the wireless station C) ≧ (the reference value of the received signal power at the wireless station C)] ], The signal power corresponding to [(received signal power at wireless station C) − (required received signal power at wireless station C)] [dB] is represented by [−R · 2 ^(M−1) ≦ Y ₄ ≦ R · 2 ^(M−1) ], and M-bit quantization (R is Q
≧ positive real number satisfying R) and to determine the value Y ₄ of the power control signals, power control signals Y ₄ and step size in the transmission signal and the information indicating that the R from the wireless station C to the radio station D When the step size is Q, the radio station D determines the transmission signal power of the radio station D based on these signals as [((transmission signal power of radio station D immediately before adjustment) − Y _3] was adjusted to [dB], when the step size is R is [(transmission signal power adjustment immediately before the radio station D) -Y _4] wireless communication method characterized by adjusting the [dB] .