JP2003037639A - Wireless impulse transmitter, receiver and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a high communication speed. SOLUTION: This wireless impulse transmitter is provided with a pulse selector, a pulse supplier and a transmission unit. The pulse selector selects a pulse form out of different pulse forms having almost the same pulse width. Each of pulse forms corresponds to a symbol in an input data stream. Each of symbols corresponds to a bit set composed of two bits at least. The pulse supplier continuously supplies pulses in the pulse form selected by the pulse selector. The transmission unit wirelessly transmits the train of pulses generated by the pulse supplier.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to wireless impulse transmitters, receivers and methods.

[0002]

2. Description of the Related Art Conventional digital communication is performed by transmitting an analog waveform representing a symbol of a message through a channel. Ultra-wide band (UWB) communication is performed by transmitting and detecting pulse trains. The pulse width is less than 1 ns and the band width is 3 GHz or more. Ultra-wideband systems are suitable for high-density multi-path, short range mobile radio communications, possibly in shielded environments.

To obtain higher communication speeds, the pulse train can be modulated with various modulation schemes before transmission. For example, the temporal position of a reference pulse called a monocycle can be modulated by pulse position modulation (PPM). The time interval of the pulses has a great influence on the achievable communication speed
The time interval required by the PPM depends on the recovery of the transmitter circuit, the accuracy of the timing circuit, and other factors. Alternatively, the amplitude of the reference pulse can be modulated by pulse amplitude modulation (PAM). However, in a wireless environment, pulse shape decays with distance. The attenuation makes it difficult for the receiver to correctly receive the pulse. This problem is not limited to the ultra-wide band communication system, but is particularly remarkable when the distance between the transmitting side and the receiving side is not constant or when more levels are added.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a radio impulse transmitter capable of achieving a high communication speed without being limited by the distance attenuation or pulse position modulation circuit in pulse amplitude modulation. To aim.

[0005]

A wireless impulse transmitter according to the present invention comprises a pulse selector, a pulse supplier and a transmission unit. The pulse selector selects from different pulse shapes having substantially the same pulse width. Each pulse shape corresponds to a symbol in the input data stream. Each symbol corresponds to a bit set consisting of at least 2 bits. The pulse supplier continuously supplies pulses in the pulse shape selected by the pulse selector.
The transmitting unit transmits a pulse train wireless transmission of the pulses generated by the pulse supplier.

In the above configuration, since each pulse shape corresponds to a symbol corresponding to a bit set consisting of at least 2 bits, the M-ary scheme is achieved without increasing the bandwidth condition in the pulse repetition rate. can do. Since the pulse characteristics can be easily changed according to the conditions in the time domain or the frequency domain, the transmitter is very flexible.

The pulse supplier preferably supplies mutually orthogonal pulse shapes. 2 defined on the interval a < x < b
The two real-valued functions g _m (t) and g _n (t) are orthogonal under the following conditions.

The pulse supplier preferably supplies a pulse shape based on a modified Hermitian polynomial. The Hermitian polynomial is transformed into an orthogonal form as follows.

In the above arrangement, the pulse duration is actually the same for all n values. That is, the time is determined independently of the pulse order. In the example of Figure 7, the pulse duration is defined as +/- 6ns. As shown in FIG. 15, all the pulses in FIG. 7, that is, order n = 0. ． ．
For 8 pulses, more than 95% of the energy is contained in the pulse duration.

There is no limit to the order of pulses.

Furthermore, the orthogonality of the pulses does not change when they are differentiated. The differentiation process is often compared to the phenomenon at the antenna.

Also, the pulse bandwidth is almost the same regardless of the order of the pulses, that is, for all values n. This is important in wireless systems. This is because by keeping the pulse width within a predetermined width, the frequency can be kept within a predetermined band.

Further, it is possible to transmit and receive a plurality of pulses at once without interfering with each other. This can further increase the bit rate of the channel in a multi-user environment.

The attenuation with distance does not increase significantly with the number of levels.

Pulses from the order n> 0 contain no DC component.

The specific bandwidth can be easily controlled by changing the center frequency. The specific bandwidth is important when designing a wideband antenna array, and the ratio of high frequency to low frequency is usually about 2 or 3.

The pulse supplier preferably supplies a pulse shape based on a modified and normalized Hermite polynomial. In this configuration, all pulses in the transmitted pulse train have approximately the same height and equal energy, so the transmission cost of all pulses is equal.

It is preferable to provide center frequency setting means for modulating the pulse train with a corresponding sine wave to modulate the center frequency of the system. Since the bandwidth of the transmitter is determined by the pulse width, the center frequency setting means can set almost any bandwidth and frequency.

The wireless impulse receiver according to the present invention comprises a receiving unit, a pulse supplier, a correlator and a data selector. The receiving unit receives wireless communication of pulse trains of pulses having substantially the same pulse width and different shapes. The pulse supplier supplies pulses having substantially the same pulse width but different shapes. In order to determine which pulse shape the pulse train is formed by, the correlator correlates the similarity between the pulse supplied by the pulse supplier and the pulse of the pulse train received by the receiving unit, and the pulse of the pulse train Output a stream of symbols corresponding to the shape. The data selector selects a bit set consisting of at least 2 bits corresponding to each symbol from the correlator. With this configuration, the same effect as the transmitter of the present invention can be obtained.

In the wireless communication method according to the present invention, each pulse shape corresponds to a symbol in the input data stream, each symbol represents a bit set of at least 2 bits, and a plurality of different pulse shapes are substantially the same. Having a pulse width, selecting one pulse shape from the plurality of different pulse shapes, continuously supplying a pulse having a pulse shape selected by a pulse selector, and supplying by the pulse supplier Wirelessly transmitting the pulse train.

With this method, the same effects as those of the transmitter and receiver of the present invention can be obtained.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an ultra wideband (UWB) communication system according to an embodiment of the present invention will be described with reference to the accompanying drawings. According to the invention, an ultra wideband communication system refers to a system having a specific bandwidth B _f greater than 25%. The specific bandwidth B _f is defined as follows. Where B is the signal bandwidth and f _c is the center frequency (center fr
frequency) and f _h are 3 dB points on the high frequency side of the signal spectrum, and f ₁ are 3 dB points on the low frequency side of the signal spectrum.

The ultra wideband communication system according to the first embodiment will be described with reference to FIGS. the system,
Communication is performed using a pulse train composed of any or all of four different pulse shapes. 4 pulse shapes each
Corresponds to one symbol. As shown below, four symbols are four 2-bit (00, 01, 10, 1
1) It corresponds to the set.

The system according to the first embodiment is shown in FIG.
M-ary wireless ultra wideband impulse transmitter 1 shown in FIG.
The receiver 100 shown in FIG. The transmitter 1 includes an input unit 10, an M-ary pulse selector 20, a reference pulse supplier 30, and a transmission unit 80. The transmission unit 80 includes an amplifier 81 and an antenna 82.

The M-ary pulse selector 20 determines which symbol the bit set in the binary data stream received from the input unit 10 corresponds to, and outputs the symbol number to the reference pulse supplier 30. In the example of FIG. 1, the data streams to the M-ary pulse selector 20 are input units 10 to 00 and 10,0.
1, 11 bit sets are provided and the M-ary pulse selector 20 has corresponding symbol numbers 1, 3, 2,
4 is output to the reference pulse supplier 30. The quadrature pulse selector 20 uses the symbol number as a function (n + 1/2) and gain. Output with the value obtained by multiplying by. This is to normalize the pulse amplitude. Here, n indicates the order of pulses, and takes a value of 1 or 2 in this example.

The reference pulse supplier 30 produces an analog pulse shape based on the selection of the M-ary pulse selector 20. That is, the reference pulse supplier 30 generates a set of different pulse shapes corresponding to the input symbol numbers. Different pulse shapes have approximately the same pulse width. According to the present embodiment, the reference pulse supplier 30 supplies a pulse shape based on a modified / normalized Hermitian polynomial having a preferable property of being orthogonal.

The Hermite polynomial is represented by the following equation.

Here, n is 1, 2, ... Is. Examples of Hermite polynomials include: These relationships are expressed by the following equations.

Here, Is Is the derivative of. As derived from the equations (4) and (5), the differential equation satisfying the Hermitian polynomial is as follows.

Hermitian polynomials are not orthogonal. By definition, two real-valued functions g defined within the range of a < x < b
_m (t) and g _n (t) are orthogonal if the following conditions are met.

A series of real-valued functions g ₁ (t), g ₂ (t), g ₃ (t), ...
Is called an orthogonal set of functions of the set. (g _{m ・}
the positive square root of g _m) is called the norm of g _m (t), Indicated by. That is,

The orthogonal standard set of functions is for all values m Meet

The Hermite polynomial is transformed to be orthogonal as follows.

It can be seen that the modified Hermitian polynomial (MHP) satisfies the following differential equation.

Fourier transform of h _n (t) into H _n (f) rewrites equations (10), (11), and (12) as follows.

Expression When Is an example when n = 0. From equation (15), it can be seen that the higher-order conversion of MHP is obtained as follows.

To increase flexibility in the frequency domain, the time function is transformed by multiplying it by an arbitrary phase-shift sinusoid.
Therefore, the modified modified / normalized Hermite polynomial (MM
NHP) is defined as follows.

Here, n = 0, 1, 2, ..., −∞ <t <
∞ and φ _r are arbitrary phases that can be zero.

A pulse based on the modified normalized Hermitian polynomial function has the following characteristics. 1. The pulse duration is practically the same for all n values. 2. The pulse bandwidth is almost the same for all n values. This is important in wireless systems. This is because if the pulse width is contained in a specific width area, the frequency can be contained in a specific band. 3. The specific bandwidth can be easily controlled by the center frequency f _c . 4. The pulses are orthogonal to each other. 5. The pulse contains no DC component. 6. The orthogonality of the pulses is maintained regardless of the differential effect of the transmitter and receiver antennas.

As shown in FIG. 2, the reference pulse supplier 30 includes a pulse train generator 31, an adder 32, two integrators 33 and 34, a pulse width controller 35, and a pulse order selector 36. Have and. FIG. 3 shows the mathematical function of each component of the reference pulse supplier 30.

The pulse train generator 31 is the reference input for the pulses and provides a pulse repetition factor (PRF) indicating the reference time unit between the pulses. According to the present embodiment, the pulse train is a pseudo noise (PN) sequence of pulses, and it is possible to avoid a specific frequency spike in a normal pulse train.

The pulse width controller 35 has a gain t of t ²
It is a monostable generator.

Where PW is the pulse width and t is the time.

The gain G is multiplied by the signal from the integrator 34.
The gain G is important because it determines the pulse width PW and the pulse bandwidth. The pulse width PW of the pulse shape illustrated in FIGS. 6 to 9 is 12.

The pulse order selector 36 determines the pulse order according to the input from the M-ary pulse selector 20. The pulse order selector 36 multiplies the value from the quadrature pulse selector 20 by the return value from the integrator 34. Adder 32 adds the output of pulse width controller 35 to the product from pulse order selector 36.

The transmission unit 80 includes a wide band antenna 82 and a power amplifier 81 for actually transmitting the pulse train of the pulses generated by the pulse supplier 30 by radio communication.

As shown in FIG. 4, the receiver 100 has a configuration substantially opposite to that of the transmitter 1 for demodulating an incoming signal. The receiver 100 includes a receiving unit 101, a timing control circuit 140, a reference pulse supplier 150, a correlator 160, an M-ary-digital data selector 170, and an output unit 180. The receiving unit 101 includes an antenna 110, a filter 120, and an amplifier 130.

When antenna 110 receives the pulse, the signal is filtered by 120 and amplified by amplifier 130. Correlator 1 to identify the corresponding symbol
Reference numeral 60 correlates a plurality of pulse shapes from the reference pulse supplier 150 with the similarity of each incoming pulse. Correlator 160
To allow for differences in time of flight between the transmitter and receiver (eg, when the transmitter and receiver move) and to allow for the inclusion of changes in PPM and PN code timing. The correlation processing is performed at the timing modified by the timing control circuit 140.

FIG. 5 shows a transmitter 1A according to the second embodiment.
Indicates. The transmitter 1A includes, in addition to the input unit 10, the M-ary pulse selector 20, the reference pulse supply unit 30, and the transmission unit 80 in the first embodiment, a modulator for increasing the effect of the system. 40, a timing circuit controller 50, an amplitude controller 60, and a filter 7
With 0 and. The modulator 40 includes a mixer 41 and a sine wave generator 42.

The modulator 40 includes a reference pulse supplier 30 so that the pulse bandwidth can be moved to any frequency range.
Sine modulation is applied to the pulse train from. This facilitates compliance with government regulations and implementation of frequency hopping.

The timing circuit controller 50 performs pulse position modulation (PPM) to increase the data rate. Information from the M-ary pulse selector 20 is used to select the level or time. In the present embodiment, the timing circuit controller 50 applies the 2-pulse position modulation to the 4-ary pulse shape modulation of the reference pulse supplier 30 and the M-ary pulse selector 20, and the data stream as follows. Encode.

Here, 0 indicates one position (shift in the reverse direction), and 1 indicates another position (shift in the positive direction).

The amplitude controller 60 uses pulse amplitude modulation (PA
M). M-ary to choose level or time
Information from the pulse selector 20 is used.

The filter 70 further removes out-of-band noise according to the transmission power and the regulation condition.

The receiver for the transmitter (having the modulator 40) in the second embodiment requires a demodulator 145 and an amplitude correlator 155, as shown by the dotted line in FIG.

FIG. 6 shows the time domain of modified / normalized Hermitian pulses of the order n = 0, 1, 2 and FIG. 7 shows the autocorrelation of these pulses.

FIG. 8 shows the time response of a modified normalized Hermite pulse to unit energy, with a pulse width PW of 12 and orders n = 3,4,5.

FIG. 9 shows the time response of a modified Hermitian pulse normalized to unit energy, with a pulse width PW of 12 and orders n = 6, 7, 8.

Although the invention has been described in detail with reference to particular embodiments, it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the scope of the appended claims and the spirit of the invention. Is.

For example, in the above-mentioned embodiment, the standard pulse supplier generates different pulse shapes, but a memory for storing different pulse shapes can be used as the pulse shape supplier.

In the above embodiment, the timing circuit controller 50 performs pulse position modulation (PPM). However, the timing circuit controller 50 uses pulse position modulation (PP
Instead of M) or in addition to pulse position modulation (PPM), pseudo noise (PN) code division may be performed.

In the above embodiment, the modified Hermitian pulse is used as the different pulse shape, but other different pulse shapes such as orthogonal wavelet pulse can be used. Further, as long as the pulse widths are substantially the same, any pulse shape set can be used.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of an M-ary UWB transmitter according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a standard pulse supplier of the transmitter shown in FIG.

FIG. 3 is a block diagram showing mathematical functions of respective components of the standard pulse supply device shown in FIG.

FIG. 4 is a block diagram showing a receiver according to the first embodiment.

FIG. 5 is a block diagram showing a transmitter according to a second embodiment of the present invention.

FIG. 6 has a pulse width PW of 12 and order n = 0,
The figure which shows the time response of the deformation | transformation / normalization Hermitian pulse of 1 and 2.

7 is a diagram showing the autocorrelation of the pulse shown in FIG.

FIG. 8 shows a pulse width PW of 12 and order n = 3.
Normalized transformation of unit energy of 4, 5
The figure which shows the time response of a normalized Hermitian pulse.

FIG. 9 shows a pulse width PW of 12 and order n = 6.
FIG. 6 shows the time response of modified Hermitian pulses normalized to unit energy of 7, 8;

[Explanation of symbols]

1, 1A ... Transmitter 10 ... Input unit 20 ... M-ary pulse selector 30 ... Reference pulse supplier 31 ... Pulse train generator 35 ... Pulse width controller 36 ... Pulse order selector 50 ... Timing circuit controller 60: Amplitude controller 70 ... Filter 80 ... Transmission unit 100 ... Receiver

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mohammad Gabami             3-14-13 Higashi Gotanda, Shinagawa-ku, Tokyo Stock             Ceremony Company Sony Computer Science Research             In-house F-term (reference) 5K004 AA01 BA01 BA02 BC00 BD00                 5K022 DD00 EE00 EE11 EE21 EE31                 5K060 BB07 CC04 CC11 FF07 HH06                       HH21 KK03

Claims (14)

[Claims] 1. Each pulse shape corresponds to each symbol in the input data stream, and each symbol has at least two.
And a pulse selector for selecting one pulse shape from the plurality of different pulse shapes, each of which represents a bit set made up of shape bits, the plurality of different pulse shapes having substantially the same pulse width. A wireless impulse transmitter, comprising: a pulse supplier that continuously supplies a pulse having a pulse shape; and a transmission unit that wirelessly transmits the pulse train supplied by the pulse supplier. 2. The wireless impulse transmitter according to claim 1, wherein the pulse shapes are orthogonal. 3. The wireless impulse transmitter according to claim 2, wherein the pulse shape is based on a modified Hermitian polynomial. 4. The wireless impulse transmitter according to claim 3, wherein the pulse shape is based on a modified / normalized Hermite polynomial. 5. The radio impulse transmitter according to claim 1, further comprising center frequency setting means for modulating the pulse train with a corresponding sine wave to modulate the center frequency of the system. 6. A receiving unit that receives wireless communication of pulse trains having substantially the same pulse width and different shapes, a pulse supplier that supplies pulses having substantially the same pulse width and different shapes, and which pulse train has which pulse. In order to determine whether it is formed in a shape, the pulse supplied from the pulse supplier and the pulse of the pulse train received by the receiving unit are correlated for similarity, and a stream of symbols corresponding to the pulse shape of the pulse train is obtained. A radio impulse receiver comprising a correlator for outputting and a data selector for selecting a bit set consisting of at least two bits corresponding to each symbol from the correlator. 7. The radio impulse receiver of claim 6, wherein the pulse supplier supplies pulse shapes that are orthogonal to each other. 8. The wireless impulse receiver of claim 7, wherein the pulse supplier supplies a pulse shape based on a modified Hermitian polynomial. 9. The wireless impulse receiver according to claim 8, wherein the pulse supplier supplies a pulse shape based on a modified / normalized Hermitian polynomial. 10. Each pulse shape corresponds to each symbol in the input data stream, each symbol representing a bit set of at least 2 bits, and different pulse shapes each having substantially the same pulse width. , A step of selecting one pulse shape from the plurality of different pulse shapes, a step of continuously supplying a pulse having a selected pulse shape, and a step of wirelessly transmitting the supplied pulse train. A characteristic wireless communication method. 11. The method of claim 10, wherein the supplied pulse shapes are orthogonal. 12. The method of claim 2, wherein the pulse shape is based on a modified Hermitian polynomial. 13. The method according to claim 12, wherein the pulse shape is based on a modified and normalized Hermite polynomial. 14. The method of claim 13 further comprising modulating the pulse train with a corresponding sine wave to modulate the center frequency of the system.