JP2002518939A - Wireless data transmission method and apparatus using FSK method, especially GFSK method - Google Patents

Abstract

(57) [Summary] In the present invention, for example, a mobile radio device for wireless data transmission by the GFSK system to which a device of the DECT system corresponds is proposed. The device has a receiver (6), a first measuring device (6) for the error rate of the received data, and a second measuring device for the electric field strength (8) when receiving the data. (3). The evaluation unit (6) processes the measured error rate and the measured electric field strength. The control unit (13) sets a frequency amplitude of the GFSK method used for wireless data transmission of the transmitter (5) of the mobile wireless device (16) depending on the measured error rate and the measured electric field strength. I do. Furthermore, for the purpose of optimizing the transmission characteristics, the evaluation unit (6) has a first table () which shows the achievable range or fault tolerance of the transmission line (15) as a function of the selected frequency amplitude. 12) and a second table (14).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates, in particular, to the FSK scheme used in accordance with the DECT standard, in particular the GF scheme.
The present invention relates to a wireless data transmission method and apparatus using the SK method.

According to the DECT standard, data is stored in GFSK (Gaussian Frequency Shift Key)
ing). For details of the DECT standard, see, for example, the well-known document "Digitale Mobilfunksysteme, Taeubner Ve" by David Benkner.
rlag, Stuttgart, 1996, ISBN 3-519-06181-3 ". According to the DECT standard, data is between 1880 and 1900 MHz (19.
(Up to 30 MHz) in the frequency domain of 120 duplex communication paths. The channel interval at that time is 1728 kHz. TDMA access method is 10ms
Frame is used. Further, a TDD system is used as a duplex system.

[0003] The present invention is applied under all FSK schemes and their derivatives.

In the case of amplitude shift keying, the amplitude of the carrier wave oscillation is changed by the modulation of the digital signal, but the frequency is kept constant, whereas in the case of frequency shift keying, the frequency shift Is inverted. That is, the information is included in the frequency. However, sudden switching from one frequency to another can lead to relatively high spectral subbands.
This causes a high bandwidth to be occupied by the transmitted signal. This property is
It can be improved by baseband filtering. A frequency filter g (t) is used, which has a smoothed course instead of a rectangular course. In this case, the smoothing function is for example accepted by a Gaussian low-pass filter.
Thereby, GFSK modulation is obtained.

The pulse response h (t) of the Gaussian low-pass filter is as follows.

[0006]

(Equation 1)

In this case, B is a limit frequency of 3 dB. This Gaussian low pass filter may be connected immediately before the modulation input side of the VCO. To the modulation input side, the following pulse generated by folding the original rectangular wave pulse and the pulse response of the Gaussian low-pass filter is applied.

[0008]

(Equation 2)

In this case, the erf (x) is a Gaussian error function as follows.

[0010]

(Equation 3)

A GFSK transmission filter is uniquely characterized by a modulation index (“BT characteristic”). FIG. 6 shows the pulse response of the transmit filter for various modulation signatures (BT). In this case, the pulse response broadens with a decrease in the modulation signature,
A "partial response" characteristic results.

For application to DECT equipment, the GFSK modulation scheme is subdivided by a nominal modulation index (BT) of 0.5. This corresponds to a frequency amplitude of 288 kHz. When determining the modulation index, the frequency amplitude is set to 202 kHz or more.
A range of 403 kHz may be acceptable.

According to the prior art, the frequency amplitude is set at a fixed value. This makes adaptation impossible.

[0014] It is therefore an object of the invention to obtain an adaptation of the wireless transmission of data according to the FSK scheme in various peripheral scenarios.

In this case, according to the consideration of the present invention, the frequency amplitude of the FSK system, for example, the GFSK system is changed depending on various parameters.

The object mentioned above is solved by the invention as set forth in the characterizing part of claims 1 and 9. Further advantageous embodiments of the invention are described in the dependent claims.

According to the present invention, there is provided a method for wireless data transmission of data according to the FSK scheme. In this case, the data is received and the error rate (BE
R, bit error rate) are measured. At the same time, the received data field strength (RSSI value)
Is measured, and the error rate and the electric field strength are evaluated. Depending on the evaluation of the error rate and the electric field strength, the frequency amplitude of the FSK method is set, and is used for wireless transmission of data in order to optimize transmission characteristics.

In this case, the frequency amplitude can be changed within a preset region.

The optimization of the transmission characteristics may be performed based on a table. This table represents the transmission range obtained depending on the set frequency amplitude.

In the case where the evaluation represents a small error rate at the same time as a small electric field strength, the frequency amplitude is optimized in the direction of the maximum reach based on the table described above.

The transmission characteristics are optimized based on the second table. This second table shows the fault tolerance of the transmission obtained depending on the set frequency amplitude.

In the case where the evaluation indicates a high error rate at the same time as the high electric field strength, the frequency amplitude is optimized in the direction of maximum fault tolerance based on the above-mentioned second table.

The transmission may be performed according to the DECT standard.

The optimal frequency amplitude may be selected with a smaller value for the maximum reach than the frequency amplitude for maximum fault tolerance.

Further according to the present invention, there is provided an apparatus for wireless transmission of data according to the FSK scheme, for example according to the DECT standard. In this case, the device
It has a receiver and a first measuring device for the bit error rate (BER, Bit Error Rate) of the received data. Further, a second measuring device for the electric field strength during the data receiving period is provided. The evaluation unit processes the measured error rate and electric field strength. Further, a control unit is provided. The frequency amplitude of the FSK method used for wireless transmission of data by the transmitter is set for optimizing transmission characteristics depending on the measured error rate and electric field strength.

Description of Embodiments Further features and advantages of the present invention will be described in detail with reference to the following embodiments and drawings. In this case, FIG. 1 is a diagram showing the structure of an apparatus for wirelessly transmitting data according to the FSK method according to the present invention, and FIG. FIG. 3 shows a bit error rate of wireless transmission depending on a signal-to-noise ratio with respect to a frequency amplitude of a noise signal of 340 kHz. FIG. 4 shows a frequency error of a noise signal of 288 kHz. 5A to 5D are diagrams showing various spectra of the GFSK signal used for the measurement according to FIGS. 2 to 4. FIG.

FIG. 6 shows a pulse response g (t) of the GFSK filter.

Although the present invention is generally applied under the FSK scheme, the description will be continued here based on, for example, the GFSK scheme.

According to the invention, depending on the set modulation index (BT value) of the FSK scheme, for example the GFSK scheme, various system characteristics of the wireless transmission emerge, for example, with respect to boundary sensitivity (range) or noise immunity. Is utilized. According to the invention, in order to obtain as large a range as possible for the transmission, the frequency amplitude chosen for it is distinguished from the frequency amplitude of the system which is optimized for maximum fault tolerance. You. Therefore, according to the present invention, the bit error rate (BER)
) And the corresponding RSSI value (Radio Signal Strength Indicator, Empfangsfeldsta
However, adaptation of the system (depending on the modulation index) can be effected in various scenarios by corresponding settings of the frequency amplitude.

As is clear from FIG. 1, the modulated digital signal is received by the antenna 1 and supplied to the receiver (receiver) 3. The receiver 3 supplies the received data (RX data) 7 on the one hand and the RSSI value 8 on the other hand to the evaluation unit 6. Specifically, the receiver 3 supplies the received data 7 and the RSSI value 8 to the control unit 13 in the evaluation unit 6.

In addition to the control unit 13, the evaluation unit 6 has a first table 12 and a second table 14, each of which is connected to the control unit 13. On the one hand, a control unit 13 in the evaluation unit 6 controls a local oscillator 4 (synthesizer), which comprises a receiver (receiver) 3 and a mobile radio 1
6 is connected to a transmitter (transmitter) 5. On the other hand, the control unit 13 of the evaluation unit 6 controls the frequency amplitude used by the transmitter 5. The evaluation unit 6 further supplies data 11 to be transmitted to the transmitter 5, which transmits this data (TX data) to a frequency amplitude 1 given by the control unit 13 in advance.
0 is modulated to the frequency of a local oscillator (synthesizer) 4 and
From the wireless transmission path 1 for transmission.

The control unit 13 of the evaluation unit 6 receives the reception data 7 and the RSSI value 8 from the receiver 3. The control unit 13 evaluates the bit error rate of the received data 7 as well as the received field strength (RSSI value) measured by the receiver 3 so that subsequent scenarios can be distinguished as follows.

Case a) When there is no or little influence by the noise signal: The received data 7 has a very small reception field strength at the same time and has no bit error rate.
In this case, the control unit 13 controls the frequency amplitude of the transmitter 5 to the maximum reach.

Case b) When there is a failure due to another signal, for example, a DECT signal: In this case, a relatively high received field strength has a relatively high bit error rate. Furthermore, in this case, the control unit 13 of the evaluation unit 6 controls the frequency amplitude of the transmitter 5 to the maximum fault tolerance.

A first table 12 and a second table 14 are provided in the evaluation unit 6 for optimizing the system for maximum reach or maximum fault tolerance. In the first table 12, the maximum achievable range of the wireless transmission section 15 is given depending on a frequency amplitude that can be selected within an allowable range. In the second table 14, the maximum fault tolerance is represented as a function of the frequency amplitude.

The tables 12 and 14 store, for example, the wireless transmission section 1 before the original transmission.
5 are created by simulation using various frequency amplitudes by analyzing the system characteristics. In FIG. 2, the bit error rate is calculated depending on the signal-to-noise ratio. The characteristic curves plotted in FIG. 2 respectively represent the corner data described below. Frequency amplitude of 202 kHz: lower limit of the accepted standard frequency amplitude of 288 kHz: nominal value frequency amplitude of 340 kHz: terminal amplitude fixed in many devices with conventional techniques fixed frequency amplitude of 403 kHz: DECT standard The ultimate conclusion of the evaluation of the diagram shown in FIG. 2 is that a frequency amplitude of 340 kHz is set under a system optimized for maximum reach,
This corresponds to case a) above.

Further simulations demonstrate the fault tolerance characterization of the DECT connection. According to the calculations shown in FIGS. 3 and 4, it is clear that in this scenario the coexistence of different systems must also be considered. For example, 3
For a noise signal with a frequency amplitude of 40 kHz (conventional DECT system),
The optimum frequency amplitude is also 340 kHz (used in the present invention) (see FIG. 3). According to the invention, for the same channel noise, 28
A nominal frequency amplitude of 8 kHz is set (FIG. 4).

5a to 5d show test signals used for the simulation.

According to the invention, the adaptation of the system in various scenarios is performed by a corresponding setting of the frequency amplitude of the FSK transmission scheme by evaluating the bit error rate and the corresponding RSSI value.

[Brief description of the drawings]

FIG. 1 shows the structure of an apparatus for wireless transmission of data according to the FSK scheme according to the present invention.

FIG. 2 is a diagram illustrating a bit error rate depending on a signal-to-noise ratio by simulation.

FIG. 3 shows a bit error rate of wireless transmission depending on a signal-to-noise ratio with respect to a frequency amplitude of a noise signal of 340 kHz.

FIG. 4 is a diagram illustrating a bit error rate depending on a signal noise resistance ratio with respect to a frequency amplitude of a 288 kHz noise signal.

FIG. 5a is used for the measurements according to FIGS. 2 to 4;

FIG. 5b is used for the measurements according to FIGS. 2 to 4;

FIG. 5c is used for the measurements according to FIGS. 2 to 4;

FIG. 5d is used for the measurements according to FIGS. 2 to 4;

FIG. 6 is a pulse response g (t) of the GFSK filter.

Claims (16)

[Claims] In a wireless data transmission method based on the FSK method, data reception (1, 3) is performed, an error rate of received data is measured (6), and an electric field strength at the time of data reception (8). Measurement (3), evaluation of the error rate and electric field strength (6), and setting of the frequency amplitude of the FSK method used for wireless data transmission (15) (
5, 6, and 10) depending on the evaluation (12) of the error rate and the electric field strength to optimize the transmission characteristics (13). 2. The method according to claim 1, wherein the frequency amplitude is changed within a preset range. 3. The transmission characteristic optimization according to claim 1, wherein the transmission characteristic is optimized based on a table (12) representing an attainable reach of the transmission section (15) depending on the set frequency amplitude. the method of. 4. If the evaluation (6) identifies a small error rate at the same time as a small electric field strength, optimization (13) of the frequency amplitude in the direction of maximum reach based on the table (12) is performed. 4. The method of claim 3, wherein the method is performed. 5. The transmission characteristic is optimized on the basis of a second table (14) representing the achievable fault tolerance of the transmission section (15) depending on the set frequency amplitude. The method according to any one of claims 1 to 4. 6. If the evaluation (6) identifies a high error rate at the same time as a high electric field strength, the frequency amplitude is optimized in the direction of maximum fault tolerance based on the second table (14). The method according to claim 5, wherein 13) is performed. 7. The method according to claim 1, wherein the transmission according to the DECT standard is performed. 8. The method according to claim 1, wherein a value smaller than the frequency amplitude for maximum fault tolerance is selected for the optimal frequency amplitude for maximum reach. 9. A wireless data transmission apparatus according to the FSK system, comprising: a receiver (3); a measuring device (6) for an error rate of received data; A measuring device (3), an evaluation unit (6) for a measured error rate and a measured electric field strength, and a control unit (13) for setting a frequency amplitude of an FSK method, wherein the control The unit (13) converts the frequency amplitude of the FSK scheme used in the wireless data transmission section (15) by the transmitter (5) into the measured error rate and the measured electric field strength in order to optimize the transmission characteristics. An apparatus characterized in that it is configured to be set dependently. 10. The apparatus according to claim 9, wherein said frequency amplitude can be changed within a preset range. 11. A table (12) is provided in the evaluation unit (6) for optimizing the transmission characteristics, the table (12) being dependent on the set frequency amplitude and the transmission section (12). 11. The device according to claim 9, which represents the achievable range of 15). 12. The optimization of the frequency amplitude in the direction of maximum reach based on the table if the evaluation unit identifies a small error rate as well as a small electric field strength. 12. The method of claim 11, wherein: 13. The method according to claim 1, further comprising the step of:
10. A table (14) is provided, said second table (14) representing the achievable fault tolerance of the transmission section (15) depending on the set frequency amplitude. Device according to any one of claims 1 to 12. 14. If the evaluation (6) identifies a high error rate at the same time as a high electric field strength, optimization of the frequency amplitude in the direction of maximum fault tolerance based on the second table (14). Apparatus according to claim 13, wherein 13) is performed. 15. The apparatus according to claim 9, wherein a value smaller than the frequency amplitude for the maximum fault tolerance is selected for the optimum frequency amplitude for the maximum reach. 16. The device according to claim 9, wherein the device is configured for a transmission according to the DECT standard.